National Primary Drinking Water Regulations: Long Term 2 Enhanced Surface Water Treatment Rule

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

[Federal Register: August 11, 2003 (Volume 68, Number 154)]
[Proposed Rules]
[Page 47689-47738]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr11au03-40]

[[pp. 47689-47738]]
National Primary Drinking Water Regulations: Long Term 2 Enhanced
Surface Water Treatment Rule

[[Continued from page 47688]]

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sedimentation basin averaging 0.20 log. Removal of aerobic spores,
total particle counts, and turbidity all correlated well with removal
of Cryptosporidium by sedimentation.
States et al. (1997) monitored Cryptosporidium removal at the
Pittsburgh Drinking Water Treatment Plant (65-70 million gallons per
day (MGD)). The clarification process included ferric chloride
coagulation, flocculation, and settling in both a small primary basin
and a 120 MG secondary sedimentation basin. Geometric mean
Cryptosporidium levels in the raw and settled water were 31 and 12
oocysts/100 L, respectively, indicating a mean reduction of 0.41 log.
Edzwald and Kelly (1998) conducted a bench-scale study to determine
the optimal coagulation conditions with different coagulants for
removing Cryptosporidium oocysts from spiked raw waters. Under optimal
coagulation conditions, the authors observed oocysts reductions through
sedimentation ranging from 0.8 to 1.2 log.
Payment and Franco (1993) measured Cryptosporidium and other
microorganisms in raw, settled, and filtered water samples from
drinking water treatment plants in the Montreal area. The geometric
mean of raw and settled water Cryptosporidium levels in one plant were
742 and 0.12 oocysts/100 L, respectively, suggesting a mean removal of
3.8 log. In a second plant, mean removal by sedimentation was reported
as 0.7 log, with raw and settled water Cryptosporidium levels reported
as <2 and <0.2 oocysts/L, respectively.
Kelley et al. (1995) monitored Cryptosporidium levels in the raw,
settled, and filtered water of two water treatment plants (designated
site A and B). Both plants included two-stage sedimentation. At site A,
mean raw and settled water Cryptosporidium levels were 60 and 9.5
oocysts/100 L, respectively, suggesting a mean removal of 0.8 log by
sedimentation. At site B, mean raw and settled water Cryptosporidium
levels were 53 and 16 oocysts/100 L, respectively, for an average
removal by sedimentation of 0.5 log. Well water was intermittently
blended in the second stage of sedimentation at site B, which may have
reduced settled and filtered water pathogen levels.
Patania et al. (1995) evaluated removal of Cryptosporidium in four
pilot scale plants. Three of these were conventional and one used in-
line filtration (rapid mix followed by filtration). Cryptosporidium
removal was generally 1.4 to 1.8 log higher in the process trains with
sedimentation compared to in-line filtration. While the effectiveness
of sedimentation for organism removal varied widely under the
conditions tested, the median removal of Cryptosporidium by
sedimentation was approximately 2.0 log.
ii. Data supplied by utilities on the removal of spores by
presedimentation. Data on the removal of Cryptosporidium and spores
(Bacillus subtilis and total aerobic spores) during operation of full-
scale presedimentation basins were collected independently and reported
by three utilities: St. Louis, MO, Kansas City, MO, and Cincinnati, OH.
Cryptosporidium oocysts were not detected in raw water at these
locations at levels sufficient to calculate log removals of oocysts
directly. However, aerobic spores were present in the raw water of
these utilities at high enough concentrations to measure log removals
through presedimentation as a surrogate for Cryptosporidium removal. As
noted earlier, data from Dugan et al. (2001) demonstrate a correlation
between removal of aerobic spores and Cryptosporidium through
sedimentation under optimal coagulation conditions. A summary of the
spore removal data supplied by the these utilities is shown in Table
IV-11.

Table IV-11.--Mean Spore Removal for Full-scale Presedimentation Basins
Reported by Three Utilities
------------------------------------------------------------------------
Reporting utility Mean spore removal
------------------------------------------------------------------------
St. Louis Water Division.................. 1.1 log (B. subtilis).
Kansas City Water Services Department..... 0.8 log (B. subtilis) (with
coagulant).
0.46 log (B. subtilis)
(without coagulant).
Cincinnati Water Works.................... 0.6 log (total aerobic
spores).
------------------------------------------------------------------------

The St. Louis Water Division operates four presedimentation basins
at one facility. Coagulant addition prior to presedimentation includes
polymer and occasional dosages of ferric sulfate. Bacillus subtilis
spore samples were collected from June 1998 to September 2000. Reported
mean spore concentrations in the raw water and following
presedimentation were 108,326 and 8,132 cfu/100 mL, respectively,
showing an average removal of 1.1 log by presedimentation.
The Kansas City Water Services Department collected Bacillus
subtilis spore samples from January to November 2000 from locations
before and after one of the facility's six presedimentation basins.
Sludge generated by the primary clarifier of a softening process was
recycled to the head of the presedimentation basins during the entire
study period. In addition, coagulant (polymer and/or ferric sulfate)
was added prior to presedimentation when raw water turbidity was
higher. During periods when coagulant was added, mean spore levels
before and after presedimentation were 102,292 and 13,154 cfu/100 mL,
respectively, demonstrating a mean removal of 0.9 log. When no ferric
sulfate or polymer was used, mean presedimentation influent and
effluent spore levels were 13,296 and 4,609 cfu/100 mL, respectively,
for an average reduction of 0.46 log.
The Cincinnati Water Works operates a treatment plant using lamella
plate settlers for presedimentation. Lamella plate settlers are
inclined plates added to a sedimentation basin to significantly
increase the surface area available for particle settling. Coagulant
(alum and polymer) is added to the raw water prior to presedimentation.
Total aerobic spore samples were collected from January 1998 through
December 2000. The mean concentration of spores decreased from 20,494
cfu/100 mL in the raw water to 4,693 cfu/100 mL in the presedimentation
effluent, indicating a mean spore removal of 0.64 log.
In conclusion, literature studies clearly establish that
sedimentation basins are capable of achieving greater than 0.5 log
reduction in Cryptosporidium levels. Further, the data supplied by
utilities on reduction in aerobic spore counts across full scale
presedimentation basins demonstrate that presedimentation can achieve
mean reductions of greater than 0.5 log under routine operating
conditions and over an extended time period. Thus, these data suggest
that a 0.5 log presumptive credit for Cryptosporidium removal by
presedimentation is appropriate under certain conditions.
With respect to the conditions under which the 0.5 log presumptive
credit for presedimentation is appropriate, the data do not demonstrate
that this level of removal can be achieved consistently without a
coagulant. In addition, available data do not establish aerobic spores
as an effective indicator of Cryptosporidium removal in the absence of
a coagulant. Thus, supporting data are consistent with a requirement
that systems apply a coagulant to be eligible for the presumptive 0.5
log presedimentation credit. Moreover, such a requirement is consistent
with the Agreement in Principle, which recommends 0.5 log credit for
presedimentation basins with a coagulant.

[[Page 47690]]

EPA also has concluded that presedimentation basins need to be
operated continuously and treat 100% of the plant flow in order to
reasonably ensure that the process will reduce influent Cryptosporidium
levels by at least 0.5 log over the course of a full year. The Agency
recognizes that, depending on influent water quality, some systems may
determine it is more prudent to operate presedimentation basins
intermittently in response to fluctuating turbidity levels. By
proposing these conditions for the presumptive presedimentation credit,
EPA is not recommending against intermittent operation of
presedimentation basins. Rather, EPA is attempting to identify the
conditions under which a 0.5 log presumptive credit for
presedimentation is warranted.
In response to the SAB panel recommendation that performance
criteria other than overflow rate be included if credit is to be given
for presedimentation, EPA analyzed the relationship between removal of
spores and reduction in turbidity through presedimentation for the
three utilities that supplied these data. Results of this analysis are
summarized in Table IV-12, which shows the relationship between monthly
mean turbidity reduction and the percent of months when mean spore
removal was at least 0.5 log.

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Within the available data set, achieving a mean turbidity reduction
of at least 0.5 log appears to provide approximately a 90% assurance
that average spore removal will be 0.5 log or greater. The underlying
data are shown graphically in Figure IV-4. Based on this information,
EPA has concluded that it is appropriate to require 0.5 log turbidity
reduction, determined as a monthly mean of daily turbidity readings, as
an operating condition for the 0.5 log presumptive Cryptosporidium
treatment credit for presedimentation. Further, EPA is proposing that
systems must meet the 0.5 log turbidity reduction requirement in at
least 11 of the 12 previous months on an ongoing basis to remain
eligible for the presedimentation credit.

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c. Request for comment. EPA requests comment on the proposed
criteria for awarding credit to presedimentation. EPA would
particularly appreciate comment on the following issues:
? Whether the information cited in this proposal supports the
proposed credit for presedimentation and the operating conditions under
which the credit will be awarded;
? Additional information that either supports or suggest
modifications to the proposed performance criteria and presumptive
credit;
? Today's proposal requires systems using presedimentation to
sample after the presedimentation basin, and these systems are not
eligible to receive additional presumptive Cryptosporidium removal
credit for presedimentation. However, systems are also required to
collect samples prior to chemical treatment, and EPA recognizes that
some plants provide chemical treatment to water prior to, or during,
presedimentation. EPA requests comment on how this situation should be
handled under the LT2ESWTR.
? Whether and under what conditions factors like low
turbidity raw water, infrequent sludge removal, and wind would make
compliance with the 0.5 log turbidity removal requirement infeasible.
6. Bank Filtration
a. What is EPA proposing today? EPA is proposing to award
additional Cryptosporidium treatment credit (0.5 or 1.0 log) for
systems that implement bank filtration as a pre-treatment technique if
it meets the design criteria specified in this section. To be eligible
for credit as a pre-treatment technique, bank filtration collection
devices must meet the following criteria:
? Wells are drilled in an unconsolidated, predominantly sandy
aquifer, as determined by grain-size analysis of recovered core
material--the recovered core must contain greater than 10% fine-grained
material (grains less than 1.0 mm diameter) in at least 90% of its
length;
? Wells are located at least 25 feet (in any direction) from
the surface water source to be eligible for 0.5 log credit; wells
located at least 50 feet from the source surface water are eligible for
1.0 log credit;
? The wellhead must be continuously monitored for turbidity
to ensure that no system failure is occurring. If the monthly average
of daily maximum turbidity values exceeds 1 NTU then the system must
report this finding to the State. The system must also conduct an
assessment to determine the cause of the high turbidity levels in the
well and consult with the State regarding whether previously allowed
credit is still appropriate.
Systems using existing bank filtration as pretreatment to a
filtration plant at the time the systems are required to conduct
Cryptosporidium monitoring, as described in section IV.A, must sample
the well effluent for the purpose of determining bin classification.
Where bin classification is based on monitoring the well effluent,
systems are not eligible to receive additional credit for

[[Page 47692]]

bank filtration. In these cases, the performance of the bank filtration
process in reducing Cryptosporidium levels will be reflected in the
monitoring results and bin classification.
Systems using bank filtered water without additional filtration
typically must collect source water samples in the surface water (i.e.,
prior to bank filtration) to determine bin classification. This applies
to systems using bank filtration to meet the Cryptosporidium removal
requirements of the IESWTR or LT1ESWTR under the provisions for
alternative filtration demonstration in 40 CFR 141.173(b) or
141.552(a). Note that the proposed bank filtration criteria for
Cryptosporidium removal credit under the LT2ESWTR do not apply to
existing State actions to provide alternative filtration
Cryptosporidium removal credit for IESWTR or LT1ESWTR compliance.
In the case of systems that use GWUDI sources without additional
filtration and that meet all the criteria for avoiding filtration in 40
CFR 141.71, samples must be collected from the ground water (e.g., the
well). Further, such systems must comply with the requirements of the
LT2ESWTR that apply to unfiltered systems, as described in section
IV.B.
b. How was this proposal developed? This section describes the bank
filtration treatment process, provides more detail on the aquifer types
and ground water collection devices that are eligible for bank
filtration credit, and describes the data supporting the proposed
requirements.
Bank filtration is a water treatment process that makes use of
surface water that has naturally infiltrated into ground water via the
river bed or bank(s) and is recovered via a pumping well. Stream-bed
infiltration is typically enhanced by the pumping action of near-stream
wells (e.g., water supply, irrigation). Bank filtrate is water drawn
into a pumping well from a nearby surface water source which has
traveled through the subsurface, either vertically, horizontally or
both, mixing to some degree with other ground water. Through bank
filtration, microorganisms and other particles are removed by contact
with the aquifer materials.
The bank filtration removal process performs most efficiently when
the aquifer is comprised of granular materials with open pore-space for
water flow around the grains. In these granular porous aquifers, the
flow path is meandering, thereby providing ample opportunity for the
organism to come into contact with and attach to a grain surface.
Although detachment can occur, it typically occurs at a very slow rate
so that organisms remain attached to a grain for long periods. When
ground water travel times from source water to well are long or when
little or no detachment occurs, most organisms will become inactivated
before they can enter a well. Thus, bank filtration relies on removal,
but also, in some cases, on inactivation to protect wells from pathogen
contamination.
Only Wells Located in Unconsolidated, Predominantly Sandy Aquifers Are
Eligible
Only granular aquifers are eligible for bank filtration credit.
Granular aquifers are those comprised of sand, clay, silt, rock
fragments, pebbles or larger particles and minor cement. The aquifer
material is required to be unconsolidated, with subsurface samples
friable upon touch. Uncemented granular aquifers are typically formed
by alluvial or glacial processes. Such aquifers are usually identified
on a detailed geologic map (e.g., labeled as Quaternary alluvium).
Under today's proposal, a system seeking Cryptosporidium removal
credit must characterize the aquifer at the well site to determine
aquifer properties. At a minimum, the aquifer characterization must
include the collection of relatively undisturbed, continuous, core
samples from the surface to a depth equal to the bottom of the well
screen. The proposed site must have substantial core recovery during
drilling operations; specifically, the recovered core length must be at
least 90% of the total projected depth to the well screen.
Samples of the recovered core must be submitted to a laboratory for
sieve analysis to determine grain size distribution over the entire
recovered core length. Each sieve sample must be acquired at regular
intervals over the length of the recovered core, with one sample
representing a composite of each two feet of recovered core. A two-foot
sampling interval reflects the necessity to sample the core frequently
without imposing an undue burden. Because it is anticipated that wells
will range from 50 to 100 foot in depth, a two-foot sampling interval
will result in about 25 to 50 samples for analysis. Each sampled
interval must be examined to determine if more than ten percent of the
grains in that interval are less than 1.0 mm in diameter (#18
sieve size). In the U.S. Department of Agriculture soil classification
system, the #18 sieve separates very coarse sands from coarse
sands. The length of core (based on the samples from two-foot
intervals) with more than ten percent of the grains less than 1.0 mm in
diameter must be summed to determine the overall core length with
sufficient fine-grained material so as to provide adequate removal. An
aquifer is eligible for removal credit if at least 90% of the sampled
core length contains sufficient fine-grained material as defined in
this section.
Cryptosporidium oocysts have a natural affinity for attaching to
fine-grained material. A study of oocyst removal in sand columns shows
greater oocyst removal in finer-grained sands than in coarser-grained
sands (Harter et al. 2000). The core sampling procedure described in
this section is designed to measure the proportion of fine-grained
sands (grains less than 1.0 mm in diameter) so as to ensure that a
potential bank filtration site is capable of retarding transport (or
removing) oocysts during ground water flow from the source surface
water to the water supply well. The value of 1.0 mm for the bounding
size of the sand grains was determined based on calculations performed
by Harter using data from Harter et al. (2000). Harter showed that, for
ground water velocities typical of a bank filtration site (1.5 to 15 m/
day), a typical bank filtration site composed of grains with a diameter
of 1.0 mm would achieve at least 1.0 log removal over a 50 foot
transport distance. Larger-sized grains would achieve less removal, all
other factors being equal.
Alluvial and glacial aquifers are complex mixtures of sand, gravel
and other sized particles. Particles of similar size are often grouped
together in the subsurface, due to sorting by flowing water that
carries and then deposits the particles. Where there exists significant
thickness of coarse-grained particles, such as gravels, with few finer
materials, there is limited opportunity for oocyst removal. When the
total gravel thickness, as measured in a core, exceeds 10%, it is more
likely (based on analysis of ground water flow within mixtures
containing differing-sized grains) that the gravel-rich intervals are
interconnected. Interconnected gravel can form a continuous,
preferential flow path from the source surface water to the water
supply well. Where such preferential flow paths exist, a preponderance
of the total ground water flow occurs within the preferential flow
path, ground water velocity is higher, and natural filtration is
minimal. A proposed bank filtration site is acceptable if at least 90%
of the core length contains grains with sufficient fine-grained
material (diameter less than 1.0 mm); that is, it is acceptable if the
core contains less than 10% gravel-rich intervals.
Aquifer materials with significant fracturing are capable of
transmitting

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ground water at high velocity in a direct flow path with little time or
opportunity for die-off or removal of microbial pathogens. Consolidated
aquifers, fractured bedrock, and karst limestone are aquifers in which
surface water may enter into a pumping well by flow along a fracture, a
solution-enhanced fracture conduit, or other preferential pathway.
Microbial pathogens found in surface water are more likely to be
transported to a well via these direct or preferential pathways.
Cryptosporidium outbreaks have been associated with consolidated
aquifers, such as a fractured chalk aquifer (Willocks et al. 1998) or a
karst limestone (solution-enhanced fractured) aquifer (Bergmire-Sweat
et al. 1999). These outbreaks show that the oocyst removal performance
of consolidated aquifers is undermined by preferential water flow and
oocyst transport through rock fractures or through rock dissolution
zones. Wells located in these aquifers are not eligible for bank
filtration credit because the flow paths are direct and the average
ground water velocity is high, so that little inactivation or removal
would be expected. Therefore, only unconsolidated aquifer are eligible
for bank filtration oocyst removal credit.
A number of devices are used for the collection of ground water
including horizontal and vertical wells, spring boxes, and infiltration
galleries. Among these, only horizontal and vertical wells are eligible
for log removal credit. The following discussion presents
characteristics of ground water collection devices and the basis for
this proposed requirement.
Horizontal wells are designed to capture large volumes of surface
water recharge. They typically are constructed by the excavation of a
central vertical caisson with laterals that extend horizontally from
the caisson bottom in all directions or only under the riverbed.
Horizontal wells are usually shallower than vertical wells because of
the construction expense. Ground water flow to a horizontal well that
extends under surface water is predominantly downward. In contrast,
ground water flow to a vertical well adjacent to surface water may be
predominantly in the horizontal direction. Surface water may have a
short ground water flow path to a horizontal well if the well extends
out beyond the bank.
Hancock et al. (1998) analyzed samples from eleven horizontal wells
and found Cryptosporidium, Giardia or both in samples from five of
those wells. These data suggest that some horizontal wells may not be
capable of achieving effective Cryptosporidium removal by bank
filtration. Insufficient data are currently available to suggest that
horizontal well distances from surface water should be greater than
distances established for vertical wells. Two ongoing studies in
Wyoming (Clancy Environmental Consultants 2002) and Nebraska (Rice
2002) are collecting data at horizontal well sites.
A spring box is located at the ground surface and is designed to
contain spring outflow and protect it from surface contamination until
the water is utilized. Spring boxes are typically located where natural
processes have enhanced and focused ground water discharge into a
smaller area and at a faster volumetric flow rate than elsewhere (i.e.,
a spring). Often, localized fracturing or solution enhanced channels
are the cause of the focused discharge to the spring orifice. Fractures
and solution channels have significant potential to transport microbial
contaminants so that natural filtration may be poor. Thus, spring boxes
are not proposed to be eligible for bank filtration credit.
Cryptosporidium monitoring results (Hancock et al. 1998) and
outbreaks are used to evaluate ground water collection devices. Hancock
et al. sampled thirty five springs for Cryptosporidium oocysts and
Giardia cysts. Most springs were used as drinking water sources and
sampling was conducted to determine if the spring should be considered
as a GWUDI source. Cryptosporidium oocysts were found in seven springs;
Giardia cysts were found in five springs; and either oocysts or cysts
were found in nine springs (26%). A waterborne cryptosporidiosis
outbreak in Medford, Oregon (Craun et al. 1998) is associated with a
spring water supply collection device. Also, a more recent, smaller
outbreak of giardiasis in an Oregon campground is associated with a PWS
using a spring. The high percentage of springs contaminated with
pathogenic protozoan, the association with recent outbreaks, and an
apparent lack of bank filtration capability indicate that spring boxes
must not be eligible for bank filtration credit.
An infiltration gallery (or filter crib) is typically a slotted
pipe installed horizontally into a trench and backfilled with granular
material. The gallery is designed to collect water infiltrating from
the surface or to intercept ground water flowing naturally toward the
surface water (Symons et al. 2000). In some treatment plants, surface
water is transported to a point above an infiltration gallery and then
allowed to infiltrate. The infiltration rate may be manipulated by
varying the properties of the backfill or the nature of the soil-water
interface. Because the filtration properties of the material overlying
an infiltration gallery may be designed or purposefully altered to
optimize oocyst removal or for other reasons, this engineered system is
not bank filtration, which relies solely on the natural properties of
the system.
A 1992 cryptosporidiosis outbreak in Talent, Oregon was associated
with poor performance of an infiltration gallery underneath Bear Creek
(Leland et al. 1993). In this case, the ground water-surface water
interface and the engineered materials beneath did not sufficiently
reduce the high oocyst concentration present in the source water. The
association of an infiltration gallery with an outbreak, the design
that relies on engineered materials rather than the filtration
properties of natural filtration media, and the shallow depth of
constructed infiltration galleries, such that they typically are not
located greater than 25 feet from the surface and surface water
recharge, all indicate that infiltration galleries must not be eligible
for bank filtration credit.
EPA notes that under the demonstration of performance credit
described in section IV.C.17, States may consider awarding
Cryptosporidium removal credit to infiltration galleries where the
State determines, based on site-specific testing with a State-approved
protocol, that such credit is appropriate (i.e., that the process
reliably achieves a specified level of Cryptosporidium removal on a
continuing basis).
Wells Located 25 Feet From the Surface Water Source Are Eligible for
0.5 Log Credit; Wells Located 50 Feet From the Surface Water Source Are
Eligible for 1.0 Log Credit
A vertical or horizontal well located adjacent to a surface water
body is eligible for bank filtration credit if there is sufficient
ground water flow path length to effectively remove oocysts. For
vertical wells, the wellhead must be located at least 25 horizontal
feet from the surface water body for 0.5 log Cryptosporidium removal
credit and at least 50 horizontal feet from the surface water body for
1.0 log Cryptosporidium removal credit. For horizontal wells, the
laterals must be located at least 25 feet distant from the normal-flow
surface water riverbed for 0.5 log Cryptosporidium removal credit and
at least 50 feet distant from the normal-flow surface water riverbed
for 1.0 log Cryptosporidium removal credit.
The ground water flow path to a vertical well is the measured
distance from the edge of the surface water body, under high flow
conditions (determined by the mapped extent of the 100 year

[[Page 47694]]

floodplain elevation boundary or floodway, as defined in Federal
Emergency Management Agency (FEMA) flood hazard maps), to the wellhead.
The ground water flow path to a horizontal well is the measured
distance from the bed of the river under normal flow conditions to the
closest horizontal well lateral.
The floodway is defined by FEMA as the area of the flood plain
where the water is likely to be deepest and fastest. The floodway is
shown on FEMA digital maps (known as Q3 flood data maps), which are
available for 11,990 communities representing 1,293 counties in the
United States. Systems may identify the distance to surface water using
either the 100 year return period flood elevation boundary or by
determining the floodway boundary using methods similar to those used
in preparing FEMA flood hazard maps. The 100 year return period flood
elevation boundary is expected to be wider than the floodway but that
difference may vary depending on local conditions. Approximately 19,200
communities in the United States have flood hazard maps that show the
100 year return period flood elevation boundary. If local FEMA floodway
hazard maps are unavailable or do not show the 100 year flood elevation
boundary, then the utility must determine either the floodway or 100
year flood elevation boundary.
The separation distance proposed for Cryptosporidium removal credit
is based, in part, on measured data for the removal of oocyst surrogate
biota in full-scale field studies. A variety of surrogate and indicator
organisms were analyzed in each study evaluated for today's proposal.
However, only two non-pathogenic organisms, anaerobic clostridia spores
and aerobic endospores, are resistant to inactivation in the
subsurface, approximately similar in size and shape to oocysts, and
sufficiently ubiquitous in both surface water and ground water so that
log removal can be calculated during passage across the surface water--
ground water interface and during transport within the aquifer.
Anaerobic spores are typically estimated at about 0.3-0.4 [mu]m in
diameter as compared with 4-6 [mu]m for oocysts. Aerobic spores, such
as endospores of the bacterium Bacillus subtilis, are slightly larger
than anaerobic spores, typically 0.5 x 1.0 x 2.0 [mu]m in diameter
(Rice et al. 1996). Experiments conducted by injecting Bacillus
subtilis spores into a gravel aquifer show that they can be very mobile
in the subsurface environment (Pang et al. 1998). As presented in the
following discussion, available data indicate similar removal of both
aerobic and anaerobic spores, either during passage across the surface
water--ground water interface or during ground water flow. These data
suggest that anaerobic spores, like aerobic spores, may be suitable
surrogate measures of Cryptosporidium removal by bank filtration.
Available data establish that during bank filtration, significant
removal of anaerobic and aerobic spores can occur during passage across
the surface water-ground water interface, with lesser removal occurring
during ground water transport within the aquifer away from that
interface. The ground water-surface water interface is typically
comprised of finer grained material that lines the bottom of the
riverbed. Typically, the thickness of the interface is small, typically
a few inches to a foot. The proposed design criteria of 25 and 50 feet
for 0.5 and 1.0 log Cryptosporidium removal credit, respectively, are
based on EPA's analysis of pathogen and surrogate monitoring data from
bank filtration sites. Most of these data are from studies of aquifers
developed in Dutch North Sea margin sand dune fields and, therefore,
represent optimal removal conditions consistent with a homogenous, well
sorted (by wind), uniform sand filter.
Medema et al. (2000) measured 3.3 log removal of anaerobic spores
during transport over a 13 m distance from the Meuse River into
adjacent ground water. Arora et al. (2000) measured greater than 2.0
log removal of anaerobic spores during transport from the Wabash River
to a horizontal collector well. Havelaar et al. (1995) measured 3.1 log
removal of anaerobic spores during transport over a 30 m distance from
the Rhine River to a well and 3.6 log removal over a 25 m distance from
the Meuse River to a well. Schijven et al. (1998) measured 1.9 log
removal of anaerobic spores over a 2 m distance from a canal to a
monitoring well. Using aerobic spores, Wang et al. (2001) measured 1.8
log removal over a 2 foot distance from the Ohio river to a monitoring
well beneath the river.
During transport solely within shallow ground water (i.e., not
including removal across the surface water-ground water interface),
Medema et al. (2000) measured approximately 0.6 log removal of
anaerobic spores over a distance of 39 feet. Using aerobic spores, Wang
et al. (2001) measured 1.0 log removal of aerobic spores over a 48 foot
distance from a monitoring well beneath a river to a horizontal well
lateral.
At distances relatively far from an injection well in a deep,
anaerobic aquifer, thereby minimizing the effects of injection,
Schijven et al. measured negligible removal of anaerobic spores over a
30 m distance. However, few bank filtration systems occur in deeper,
anaerobic ground water so these data may not apply to a typical bank
filtration system in the United States.
These data demonstrate that during normal and low surface water
elevations, the surface water-ground water interface performs
effectively to remove microbial contamination. However, there will
typically be high water elevation periods during the year, especially
on uncontrolled rivers, that alter the nature and performance of the
interface due to flood scour, typically for short periods. During these
periods, lower removals would be expected to occur.
Averaging Cryptosporidium oocyst removal over the period of a year
requires consideration of both high and low removal periods. During
most of the year, high log removal rates would be expected to
predominate (e.g., 3.3 log removal over 42 feet) due to the removal
achieved during passage across the surface water-ground water
interface. During short periods of flooding, substantially lower
removal rates may occur (e.g., 0.5 log removal over 39 feet) due to
scouring of the riverbed and removal of the protective, fine-grained
material. By considering all time intervals with differing removal
rates over the period of a year, EPA is proposing that 0.5 log removal
over 25 feet (8 m) and 1.0 log removal over 50 feet (16 m) are
reasonable estimates of the average performance of a bank filtration
system over a year. This proposal is generally supported by colloidal
filtration theory modeling results using data characteristic of the
aquifers in Louisville and Cincinnati and column studies of oocyst
transport in sand (Harter et al. 2000).
Wells must be continuously monitored for turbidity
Under the Surface Water Treatment Rule (40 CFR 141.73(b)(1)) the
turbidity level of slow sand filtered water must be 1 NTU or less in
95% of the measurements taken each month. Turbidity sampling is
required once every four hours, but may be reduced to once per day
under certain conditions. Although slow sand filtration is not bank
filtration, similar pathogen removal mechanisms are expected to occur
in both processes. Just as turbidity monitoring is used to provide
assurance that the removal credit assigned to a slow sand filter is
being realized, EPA

[[Page 47695]]

is proposing continuous turbidity monitoring for all bank filtration
wells that receive credit.
If monthly average turbidity levels (based on daily maximum values
in the well) exceed 1 NTU, the system is required to report to the
State and present an assessment of whether microbial removal has been
compromised. If the State determines that microbial removal has been
compromised, the system must not receive credit for bank filtration
until the problem has been remediated. The turbidity performance
requirement for bank filtration is less strict than that for slow sand
filtration because, unlike slow sand filtration, bank filtration is a
pre-treatment technique followed by conventional or direct filtration.
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In summary, EPA believes that the measured full-scale field data
from operating bank filtration systems, the turbidity monitoring
provision, and the design criteria for aquifer material, collection
device type, and setback distance, together provide assurance that the
presumptive log removal credit will be achieved by bank filtration
systems that conform to the requirements in today's proposal.
c. Request for comment. The Agency requests comment on the
following issues concerning bank filtration:
? The performance of bank filtration in removing
Cryptosporidium or surrogates to date at sites currently using this
technology (e.g. sites with horizontal wells).
? The use of other methods (e.g., geophysical methods such as
ground penetrating radar) to complement or supplant core drilling to
determine site suitability for bank filtration credit.
? The number of GWUDI systems in each State (i.e., the number
of systems having at least one GWUDI source) where bank filtration has
been utilized as the primary filtration barrier (e.g., no other
physical removal technologies follow); also, the method that was used
by the State to determine that each

[[Page 47696]]

system was achieving 2 log removal of Cryptosporidium.
? For GWUDI systems where natural or alternative filtration
(e.g. bank filtration or artificial recharge) is used in combination
with a subsequent filtration barrier (e.g., bag or cartridge filters)
to meet the 2 log Cryptosporidium removal requirement of the IESWTR or
LT1ESWTR, how much Cryptosporidium removal credit has the State awarded
(or is the State willing to grant if the bags/cartridges were found to
be achieving < 2.0 logs) for the natural or alternative filtration
process and how did the State determine this value?
? The proposed Cryptosporidium removal credit and associated
design criteria, including any additional information related to this
topic.
? Suitable separation distance(s) to be required between
vertical or horizontal wells and adjacent surface water.
? Testing protocols and procedures for making site specific
determinations of the appropriate level of Cryptosporidium removal
credit to award to bank filtration processes.
? Information on the data and methods suitable for predicting
Cryptosporidium removal based on the available data from surrogate and
indicator measurements in water collection devices.
? The applicability of turbidity monitoring or other process
monitoring procedures to indicate the ongoing performance of bank
filtration processes.
7. Lime Softening
a. What is EPA proposing today? Lime softening is a drinking water
treatment process that uses precipitation with lime and other chemicals
to reduce hardness and enhance clarification prior to filtration. Lime
softening can be categorized into two general types: (1) Single-stage
softening, which is used to remove calcium hardness and (2) two-stage
softening, which is used to remove magnesium hardness and greater
levels of calcium hardness. A single-stage softening plant includes a
primary clarifier and filtration components. A two-stage softening
plant also includes a secondary clarifier located between the primary
clarifier and filter. In some two-stage softening plants, a portion of
the flow bypasses the first clarifier.
EPA has determined that lime softening plants in compliance with
IESWTR or LT1ESWTR achieve a level of Cryptosporidium removal
equivalent to conventional treatment plants (i.e., average of 3 log).
Consequently, lime softening plants that are placed in Bins 2-4 as a
result of Cryptosporidium monitoring incur the same additional
treatment requirements as conventional plants. However, EPA is
proposing that two-stage softening plants be eligible for an additional
0.5 log Cryptosporidium treatment credit. To receive the 0.5 log
credit, the plant must have a second clarification stage between the
primary clarifier and filter that is operated continuously, and both
clarification stages must treat 100% of the plant flow. In addition, a
coagulant must be present in both clarifiers (may include metal salts,
polymers, lime, or magnesium precipitation).
b. How was this proposal developed? The lime softening process is
used to remove hardness, primarily calcium and magnesium, through
chemical precipitation followed by sedimentation and filtration. The
addition of lime increases pH, causing the metal ions to precipitate.
Other contaminants can coalesce with the precipitates and be removed in
the subsequent settling and filtration processes. While elevated pH has
been shown to inactivate some microorganisms like viruses (Battigelli
and Sobsey, 1993, Logsdon et al. 1994), current research indicates that
Cryptosporidium and Giardia are not inactivated by high pH (Logsdon et
al. 1994, Li et al. 2001). A two-stage lime softening plant has the
potential for additional Cryptosporidium removal because of the
additional sedimentation process.
Limited data are available on the removal of Cryptosporidium by the
lime softening treatment process. EPA has evaluated data from a study
by Logsdon et al. (1994), which investigated removal of Giardia and
Cryptosporidium in full scale lime softening plants. In addition, the
Agency has considered data provided by utilities on the removal of
aerobic spores in softening plants. These data are summarized in the
following paragraphs.
Logsdon et al. (1994) measured levels of Cryptosporidium and
Giardia in the raw, settled, and filtered water of 13 surface water
plants using lime softening. Cryptosporidium was detected in the raw
water at 5 utilities: one single-stage plant and four two-stage plants.
Using measured oocyst levels, Cryptosporidium removal by sedimentation
was 1.0 log in the single-stage plant and 1.1 to 2.3 log in the two-
stage plants. Cryptosporidium was found in two filtered water samples
of the single stage plant, leading to calculated removals from raw to
filtered water of 0.6 and 2.2 log. None of the two-stage plants had
Cryptosporidium detected in the filtered water. Based on detection
limits, calculated Cryptosporidium removals from raw to filtered water
in the two-stage plants ranged from £2.67 to £3.85
log.
Giardia removal across sedimentation was £0.9 log for a
single-stage plant and ranged from 0.8 to 3.2 log for two-stage plants,
based on measured cyst levels. Removal of Giardia from raw water
through filtration was calculated using detection limits as
£1.5 log in a single-stage plant and ranged from
£0.9 to £3.3 log in two-stage plants.
While results from the Logsdon et al. study are constrained by
sample number and method detection limits, they suggest that two-stage
softening plants may achieve greater removal of Cryptosporidium than
single-stage plants. The authors concluded that two stages of
sedimentation, each preceded by effective flocculation of particulate
matter, may increase removal of protozoa. Additionally, the authors
stated that consistent achievement of flocculation that results in
effective settling in each sedimentation basin is the key factor in
this treatment process.

Removal of Aerobic Spores by Softening Plants

Additional information on the microbial removal efficiency of the
lime softening process comes from data provided by softening plants on
removal of aerobic spores. While few treatment plants have sufficient
concentrations of oocysts to directly calculate a Cryptosporidium
removal efficiency, some plants have high concentrations of aerobic
spores in the raw water. Spores may serve as an indicator of
Cryptosporidium removal by sedimentation and filtration (Dugan et al.
2001).
The following two-stage softening plants provided data on removal
of aerobic spores: St. Louis, MO, Kansas City, MO, and Columbus, OH (2
plants). Cryptosporidium data were also collected at these utilities,
but it was not possible to calculate oocyst removal due to low raw
water detection rates. Data on removal of aerobic spores by these
softening plants is summarized in Table IV-14.

[[Page 47697]]

Table IV-14.--Summary of Aerobic Spore Removal Data From Softening Plants
----------------------------------------------------------------------------------------------------------------
Mean log removal of aerobic spores
-----------------------------------------------
Plant Primary Secondary
clarifier clarifier Across plant *
----------------------------------------------------------------------------------------------------------------
St. Louis....................................................... 1.7 1.1 3.8
Kansas City..................................................... 2.4 0 3.4
Columbus Plant 1................................................ 1.2 1.6 3.1
Columbus Plant 2................................................ 1.3 2.4 4.2
----------------------------------------------------------------------------------------------------------------
* Excludes removal in pre-sedimentation basins; calculated spore removal may underestimate actual removal due to
filter effluent levels below quantitation limits.

The City of St. Louis Water Division operates a two-stage lime
softening process preceded by presedimentation. Ferric sulfate and
polymer coagulants are added at various points in the process. St.
Louis collected Bacillus subtilis spore samples between June 1998 and
September 2000. During this time period, the mean spore concentration
entering the softening process (i.e., after presedimentation) was 8,132
cfu/100 mL. The log removal values shown in Table IV-14 are based on
average spore concentrations following primary clarification, secondary
clarification, and filtration. However, spore levels in some filtered
water samples were below the method detection limit, so that the true
mean spore removal across the plant may have been higher than indicated
by the calculated value.
The Kansas City Water Services Department plant includes two-stage
lime softening with pre-sedimentation and sludge recycle. Bacillus
subtilis spore data were collected from this plant during January
through November 2000. The mean spore concentration entering the lime
softening process (after presedimentation) was 5,965 cfu/100 mL. Mean
spore levels following primary clarification, secondary clarification,
and filtration were 21.1, 25.7, and 2.6 cfu/100 mL, respectively.
Corresponding log removal values are shown in Table IV-14. Note that
the average spore concentration in the effluent of the secondary
clarifier was essentially equivalent to the effluent of the primary
clarifier, indicating that little removal occurred in the secondary
clarifier. This result may have been due to the high removal achieved
in the primary clarifier and, consequently, the relatively low
concentration of spores entering the second clarifier. As with the St.
Louis plant, many of the filtered water observations were below method
detection limits, so actual log removal across the plant may have been
higher than the calculated value.
The City of Columbus operates two lime softening plants, each of
which has two clarification stages. Coagulant is added prior to the
first clarification stage but lime is not added until the second
clarifier (i.e., first clarifier is not a softening stage). Between
1997 and 2000, samples for total aerobic spores were collected
approximately monthly at each plant from raw water, following each
clarification basin, and after filtration. Mean spore concentrations in
the raw water sources for the two plants were 10,619 cfu/100 mL (Plant
1) and 22,595 cfu/100 mL (Plant 2). Mean log removals occurring in the
two clarification stages and across the plant are shown for each plant
in Table IV-14.
These data indicate that two-stage softening plants can remove high
levels of Cryptosporidium, and, in particular, that a second
clarification stage can achieve 0.5 log or greater removal. Three of
the four plants that provided data on removal of aerobic spores
achieved greater than 1 log reduction in the second clarifier. Kansas
City, the one plant which achieved little removal in the second
clarifier, achieved a mean 2.4 log removal in the primary clarifier.
This was approximately 1 log more reduction than achieved in the
primary clarifiers of the other three plants, so that the spore
concentration entering the second clarifier in Kansas City may have
been too low to serve as an indicator of removal efficiency.
Consequently, EPA has concluded that these data support an additional
Cryptosporidium treatment credit of 0.5 log for a two-stage softening
plant.
EPA is proposing as a condition of the 0.5 log additional credit
that a coagulant, which could include excess lime and soda ash or
precipitation of magnesium hydroxide, be present in both clarifiers.
This requirement is necessary to ensure that significant particulate
removal occurs in both clarification stages. Logsdon et al. (1994)
identified effective flocculation as being a key factor for removal of
protozoa in softening plants. Among the softening plants that provided
data on aerobic spore removal, St. Louis added ferric and polymer
coagulants at different points in the process, and the two Columbus
plants added lime to the second clarifier. Consequently, a requirement
that plants add a coagulant, which may be lime, in the secondary
clarifier is consistent with the data used to support the 0.5 log
additional credit.
The Science Advisory Board (SAB) reviewed the proposed
Cryptosporidium treatment credit for lime softening and supporting
information, as presented in the November 2001 pre-proposal draft of
the LT2ESWTR (USEPA 2001g). In written comments from a December 2001
meeting of the Drinking Water Committee, the SAB panel concluded that
both single- and two-stage softening generally outperform conventional
treatment due to the heavy precipitation that occurs. Further, the
panel found that 0.5 log of additional Cryptosporidium removal is an
average value for a two-stage lime softening plant. However, the SAB
stated that the additional credit for two-stage softening should be
given only if all the water passes through both stages. Today's
proposal is consistent with these recommendations by the SAB.
EPA notes that by including a presumptive credit for softening
plants, today's proposal differs from the Stage 2 M-DBP Agreement in
Principle, which recommends up to 1 log additional Cryptosporidium
treatment credit for softening plants based on demonstration of
performance, but no additional presumptive credit.
c. Request for comment. EPA requests comment on the proposed
criteria for awarding credit to lime softening plants. EPA would
particularly appreciate comment on the following issues:
? Whether the information and analyses presented in this
proposal supports an additional 0.5 log credit for two-stage softening,
and the associated criteria necessary for credit.
? Additional information that either support or suggest
modifications to the proposed criteria and credit.
8. Combined Filter Performance
a. What is EPA proposing today? This toolbox component will grant
additional credit towards Cryptosporidium

[[Page 47698]]

treatment requirements to certain plants that maintain finished water
turbidity at levels significantly lower than currently required. EPA is
proposing to award an additional 0.5 log Cryptosporidium treatment
credit to conventional and direct filtration plants that demonstrate a
turbidity level in the combined filter effluent (CFE) less than or
equal to 0.15 NTU in at least 95 percent of the measurements taken each
month. Compliance with this criterion must be based on measurements of
the CFE every four hours (or more frequently) that the system serves
water to the public. This credit is not available to membrane, bag/
cartridge, slow sand, or DE plants, due to the lack of documented
correlation between effluent turbidity and Cryptosporidium removal in
these processes.
b. How was this proposal developed? Turbidity is an optical
property measured from the amount of light scattered by suspended
particles in a solution. It is a method defined parameter that can
detect the presence of a wide variety of particles in water (e.g.,
clay, silt, mineral particles, organic and inorganic matter, and
microorganisms), but it cannot provide specific information on particle
type, number, or size. Turbidity is used as an indicator of raw and
finished water quality and treatment performance. Turbidity spikes in
filtered water indicate a potential for breakthrough of pathogens.
Under the IESWTR and LT1ESWTR, combined filter effluent turbidity
in conventional and direct filtration plants must be less than or equal
to 0.3 NTU in 95% of samples taken each month and must never exceed 1
NTU. These plants are also required to conduct continuous monitoring of
turbidity for each individual filter, and provide an exceptions report
to the State when certain criteria for individual filter effluent
turbidity are exceeded (described in 63 FR 69487, December 16, 1998)
(USEPA 1998a).
The Stage 2 M-DBP Advisory Committee recommended that systems
receive an additional 0.5 log Cryptosporidium removal credit for
maintaining 95th percentile combined filter effluent turbidity below
0.15 NTU, which is one half of the current required level of 0.3 NTU.
In considering the technical basis to support this recommendation, EPA
has reviewed studies that evaluated the efficiency of granular media
filtration in removing Cryptosporidium when operating at different
effluent turbidity levels.
For the IESWTR, EPA estimated that plants would target filter
effluent turbidity in the range of 0.2 NTU in order to ensure
compliance with a turbidity standard of 0.3 NTU. Similarly, EPA has
estimated that plants relying on meeting a turbidity standard of 0.15
NTU in 95% of samples will consistently operate below 0.1 NTU in order
to ensure compliance. Consequently, to assess the impact of compliance
with the lower finished water turbidity standard, EPA compared
Cryptosporidium removal efficiency when effluent turbidity is below 0.1
NTU with removal efficiency when effluent turbidity is in the range of
0.1 to 0.2 NTU. Results from applicable studies are summarized in Table
IV-15 and are discussed in the following paragraphs.

Table IV-15.--Studies of Cryptosporidium Removal at Different Effluent Turbidity Levels
--------------------------------------------------------------------------------------------------------------------------------------------------------
Average of log Filtered effluent
Microorganism removals turbidity Experiment design Researcher
--------------------------------------------------------------------------------------------------------------------------------------------------------
Cryptosporidium..................... 4.39 <=0.1 NTU.............. Pilot-scale.................... Patania et al. (1995).
3.55 £0.1 and
<=0.2 NTU
Giardia............................. 4.23 <=0.1 NTU
3.22 £0.1 and
<=0.2 NTU
Cryptosporidium..................... 4.09 <=0.1 NTU.............. Bench-scale.................... Emelko et al. (1999).
3.58 £0.1 and
<=0.2 NTU
Cryptosporidium..................... 3.76 <=0.1 NTU Pilot-scale.................... Dugan et al. (2001).
2.56 £0.1 and
<=0.2 NTU
--------------------------------------------------------------------------------------------------------------------------------------------------------

Patania et al. (1995) conducted pilot-scale studies at four
locations to evaluate the removal of seeded Cryptosporidium and
Giardia, turbidity, and particles. Treatment processes, coagulants, and
coagulant doses differed among the four locations. Samples of filter
effluent were taken at times of stable operation and filter maturation.
Analysis of summary data from the seeded runs at all locations shows
that average Cryptosporidium removal was greater by more than 0.5 log
when effluent turbidity was less than 0.1 NTU, in comparison to removal
with effluent turbidity in the range 0.1 to 0.2 NTU (see Table IV-15).
Emelko et al. (1999) used a bench scale dual media filter to study
Cryptosporidium removal during both optimal and challenged operating
conditions. Water containing a suspension of kaolinite (clay) was
spiked with oocysts, coagulated in-line with alum, and filtered. Oocyst
removal was evaluated during stable operation when effluent turbidity
was below 0.1 NTU. Removal was also measured after a hydraulic surge
that caused process upset, and with coagulant addition terminated.
These later two conditions resulted in effluent turbidities greater
than 0.1 NTU and decreased removal of Cryptosporidium. As shown in
Table IV-15, average removal of Cryptosporidium during periods with
effluent turbidity below 0.1 NTU was approximately 0.5 log greater than
when effluent turbidity was between 0.1 to 0.2 NTU.
Dugan et al. (2001) evaluated Cryptosporidium removal in a pilot
scale conventional treatment plant. Sixteen filtration runs seeded with
Cryptosporidium were conducted at different raw water turbidities and
coagulation conditions. Eleven of the runs had an effluent turbidity
below 0.1 NTU, and five runs had effluent turbidity between 0.1 and 0.2
NTU. For runs where the calculated Cryptosporidium removal was
concentration limited (i.e., effluent values were non-detect), the
method detection limit was used to calculate the values shown in Table
IV-15. Using this conservative estimate, average Cryptosporidium
removal with effluent turbidity below 0.1 NTU exceeded by more than 1
log the average removal observed with effluent turbidity between 0.1 to
0.2 NTU.
In summary, these three studies all support today's proposal in
showing that plants consistently operating below 0.1 NTU can achieve an
additional 0.5 log or greater removal of Cryptosporidium than when
operating between 0.1 and 0.2 NTU. Because EPA expects plants relying
on compliance with a 0.15 NTU standard will consistently operate below
0.1 NTU, the

[[Page 47699]]

Agency has determined it is appropriate to propose an additional 0.5
log treatment credit for plants meeting this standard.
The SAB reviewed the proposed additional 0.5 log Cryptosporidium
removal credit for systems maintaining very low CFE turbidity, as
presented in the November 2001 pre-proposal draft of the LT2ESWTR
(USEPA 2001g). The SAB also reviewed a potential additional 1.0 log
Cryptosporidium removal credit for systems achieving very low
individual filter effluent (IFE) turbidity, which is addressed in
section IV.C.16 of today's proposal.
In written comments from a December 2001 meeting of the Drinking
Water Committee, the SAB panel stated that additional credit for lower
finished water turbidity is consistent with what is known in both pilot
and full-scale operational experiences for Cryptosporidium removal.
Recognizing that IESWTR requirements for lowering turbidity in the
treated water will result in lower concentrations of Cryptosporidium,
the panel affirmed that even further lowering of turbidity will result
in further reductions in Cryptosporidium in the filter effluent.
However, the SAB concluded that limited data were presented to show the
exact removal that can be achieved, and recommended that no additional
credit be given to plants that demonstrate CFE turbidity of 0.15 NTU or
less. The SAB recommended that 0.5 log credit be given to plants
achieving IFE turbidity in each filter less than 0.15 NTU in 95% of
samples each month.
In responding to this recommendation from the SAB, EPA acknowledges
the difficulty in precisely quantifying Cryptosporidium removal through
filtration based on effluent turbidity levels. Nevertheless, EPA finds
that available data consistently show that removal of Cryptosporidium
is increased by 0.5 log or greater when filter effluent turbidity is
reduced to levels reflecting compliance with a 0.15 NTU standard, in
comparison to compliance with a 0.3 NTU standard. Consequently, EPA has
concluded that it is appropriate to propose this 0.5 log presumptive
treatment credit for systems achieving very low CFE turbidity.
Measurement of Low Level Turbidity
Another important aspect of proposing to award additional removal
credit for lower finished water turbidity is the performance of
turbidimeters in measuring turbidity below 0.3 NTU. The following
paragraphs summarize results from several studies that evaluated low
level measurement of turbidity by different on-line and bench top
instruments. Note that because compliance with the CFE turbidity limit
is based on 4-hour readings, either on-line or bench top turbidimeters
may be used. EPA believes that results from these studies indicate that
currently available turbidity monitoring equipment is capable of
reliably assessing turbidity at levels below 0.1 NTU, provided
instruments are well calibrated and maintained.
The 1997 NODA for the IESWTR (67 FR 59502, Nov. 3, 1997) (USEPA
1997a) discusses issues relating to the accuracy and precision of low
level turbidity measurements. This document cites studies (Hart et al.
1992, Sethi et al. 1997) suggesting that large tolerances in instrument
design criteria have led to turbidimeters that provide different
turbidity readings for a given suspension.
At the time of IESWTR NODA, EPA had conducted performance
evaluation (PE) studies of turbidity samples above 0.3 NTU. A
subsequent PE study (USEPA 1998e), labeled WS041, was carried out to
address concern among the Stage 1 M-DBP Federal Advisory Committee
regarding the ability to reliably measure lower turbidity levels. The
study involved distribution of different types of laboratory prepared
standard solutions with reported turbidity values of 0.150 NTU or 0.160
NTU. The results of this study are summarized in Table IV-16.
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The data summarized in Table IV-16 indicate a positive bias for all
instruments when compared against a reported ``true value.'' On-line
instruments in this study had a larger positive bias and higher
standard deviation (RSD approximately 50 percent). The positive bias is
consistent with previous PE studies (USEPA 1998e) and suggests that
error in turbidimeter readings may be generally conservative (i.e.,
systems will operate

[[Page 47700]]

at lower than required effluent turbidity levels).
Letterman et al. (2001) evaluated the effect of turbidimeter design
and calibration methods on inter-instrument performance, comparing
bench top to on-line instruments and instruments within each of those
categories from different manufacturers. The study used treated water
collected from the filter effluent of water treatment plants. Reported
sample turbidity values ranged from 0.05 to 1 NTU. Samples were
analyzed in a laboratory environment. The results are consistent with
those of the WS041 study, specifically the positive bias of on-line
instruments. However, Letterman et al. found generally poor agreement
among different on-line instruments and between bench-top and on-line
instruments. The authors also observed that results were independent of
the calibration method, though certain experiments suggested that
analyst experience may have some effect on turbidity readings from
bench-top instruments.
Sadar (1999) conducted an intra-instrument study of low level
turbidity measurements among instruments from the same manufacturer.
This study was performed under well-controlled laboratory conditions.
Intra-instrument variation among different models and between bench top
and on-line instruments occurred but at significantly lower levels than
the Letterman et al. inter-instrument study. Newer instruments also
tended to read lower than older instruments, which the author
attributed to a reduction in stray light and lower sensitivities in the
newer instruments. Sadar also found a generally positive bias when
comparing on-line to bench-top and when comparing all instruments to a
prepared standard.
The American Society for Testing and Materials (ASTM) has issued
standard test methods for measurement of turbidity below 5 NTU by on-
line (ASTM 2001) and static (ASTM 2003) instrument modes. The methods
specify that the instrument should permit detection of turbidity
differences of 0.01 NTU or less in waters having turbidities of less
than 1.00 NTU (ASTM 2001) and 5.0 NTU (ASTM 2003), respectively. Inter-
laboratory study data included with the method for a known turbidity
standard of 0.122 NTU show an analyst relative deviation of 7.5% and a
laboratory relative deviation of 16% (ASTM 2003).
In summary, the data collected in these studies of turbidity
measurement indicate that currently available monitoring equipment can
reliably measure turbidity at levels of 0.1 NTU and lower. However,
this requires rigorous calibration and verification procedures, as well
as diligent maintenance of turbidity monitoring equipment (Burlingame
1998, Sadar 1999). Systems that pursue additional treatment credit for
lower finished water turbidity must develop the procedures necessary to
ensure accurate and reliable measurement of turbidity at levels of 0.1
NTU and less. EPA guidance for the microbial toolbox will provide
direction to water systems on developing these procedures.
c. Request for comment. EPA invites comment on the following issues
regarding the proposed Cryptosporidium treatment credit for combined
filter performance:
? Do the studies cited here support awarding 0.5 log credit
for CFE <= 0.15 NTU 95% of the time?
? Does currently available turbidity monitoring technology
accurately distinguish differences between values measured near 0.15
NTU?
9. Roughing Filter
a. What is EPA proposing today? The Stage 2 M-DBP Agreement in
Principle recommends a 0.5 log presumptive credit towards additional
Cryptosporidium treatment requirements for roughing filters. However,
the Agreement further specifies that EPA is to determine the design and
implementation criteria under which the credit would be awarded. Upon
subsequent review of available literature, EPA is unable to identify
design and implementation conditions for roughing filters that would
provide reasonable assurance of achieving a 0.5 log removal of oocysts.
Consequently, EPA is not proposing presumptive credit for
Cryptosporidium removal by roughing filters. Today's proposal does,
though, include a 0.5 log credit for a second granular media filter
following coagulation and primary filtration (see section IV.C.13).
b. How was this proposal developed? Roughing filtration is a
technique used primarily in developing countries to remove solids from
high turbidity source waters prior to treatment with slow sand filters.
Typically, roughing filters consist of a series of sedimentation tanks
filled with progressively smaller diameter media in the direction of
flow. The media can be gravel, plastic, crushed coconut, rice husks, or
a similar locally available material. The flow direction in roughing
filters can be either horizontal or vertical, and vertical roughing
filters can be either upflow or downflow. The media in the tanks
effectively reduce the vertical settling distance of particles to a
distance of a few millimeters. As sediment builds on the media, it
eventually sloughs off and begins to accumulate in the lower section of
the filter, while simultaneously regenerating the upper portions of the
filter. The filters require periodic cleaning to remove the collected
silt.
Review of the scientific and technical literature pertaining to
roughing filters has identified no information on removal of
Cryptosporidium. Information is available on removal of suspended
solids, turbidity, particles, fecal coliforms and some algae, but none
of these has been demonstrated to be an indicator of Cryptosporidium
removal by roughing filters. Moreover, roughing filters are not
preceded by a coagulation step, and studies have found that some
potential surrogates, such as aerobic spores, are not conservative
indicators of Cryptosporidium removal by filtration when a coagulant is
not present (Yates et al. 1998, Dugan et al. 2001). Thus, it is unclear
how to relate results from studies of the removal of other particles by
roughing filters to potential removal of Cryptosporidium.
In addition, some studies have observed very poor removal of
Cryptosporidium by rapid sand filters when a coagulant is not used
(Patania et al. 1995, Huck et al. 2000). Based on these findings, it is
expected that there would be situations where a roughing filter would
not achieve 0.5 log Cryptosporidium removal. Because available data are
insufficient to determine the conditions that would be necessary for a
roughing filter to achieve 0.5 log Cryptosporidium removal, EPA is
unable to propose this credit. The following discussion describes four
studies that analyzed the effectiveness of roughing filters for
removing solids, turbidity, particles, fecal coliforms, and algae.
Wegelin et al. (1987) conducted pilot-scale studies on the use of
horizontal roughing filters to reduce solids, turbidity, and particles.
Testing was performed to determine the influence of different design
parameters on filter performance. Data from the parameter testing was
used to establish an empirical model to simulate filtrate quality as a
function of filter length and time for a given filter configuration.
Using the mathematical model, the researchers found that long filters
(10 m) at low filtration rates (0.5 m/h) were capable of reducing high
suspended solids concentrations (1000 mg/L TSS) down to less than 3 mg/
L.
Further work by Wegelin (1988) evaluated roughing filters as
pretreatment for slow sand filters for

[[Page 47701]]

waters with variable and seasonably high suspended solids
concentrations. This study collected data on roughing filters in Peru,
Colombia, Sudan, and Ghana. Table IV-17 summarizes data for three of
the roughing filters. These filters were capable of reducing peak
turbidities by 80 to 90 percent. Further, the Peruvian and Colombian
filters reduced fecal coliforms by 77 and 89 percent, respectively. The
Sudanese filter may have removed around 90 percent of the fecal
coliforms, but specific values were not given. Data collected from
roughing filters in Ghana on algae removal indicate that the
Merismopedia (0.5 [mu]m) and Chlorophyta (2-10 [mu]m), which are
comparable in size to Cryptosporidium oocysts, were completely removed
from the water in mature filters, and that some removal of Chlorophyta,
but not Merismopedia, occurred in filters after three days of
operation. However, the removal of these organisms has not been
correlated with Cryptosporidium oocyst removal.

Table IV-17.--Roughing Filter Data From Wegelin, 1988
----------------------------------------------------------------------------------------------------------------
Location Azpita, Peru El Retiro, Colombia Blue Nile Health Project, Sudan
----------------------------------------------------------------------------------------------------------------
Roughing Filter Type............ Downflow........... Upflow (multi-layer Horizontal-flow.
filter).
Filtration Rate................. 0.30 m/h (0.98 ft/ 0.74 m/h (2.43 f/ 0.3 m/h (0.98 ft/hr).
hr). hr).
Design Capacity................. 35 m3/d............ 790 m3/d........... 5 m3/d.
---------------------------------
Turbidity (NTU)
----------------------------------------------------------------------------------------------------------------
Raw Water....................... 50-200............. 10-150............. 40-500
Roughing Filter Effluent........ 15-40.............. 5-15............... 5-50
---------------------------------
Fecal Coliforms (/100 mL)
----------------------------------------------------------------------------------------------------------------
Raw Water....................... 700................ 16,000............. £300
Roughing Filter Effluent........ 160................ 1,680.............. <25
----------------------------------------------------------------------------------------------------------------

oller (1993) details the mechanisms of particle removal that occur
in roughing filters. The conclusions are similar to those drawn by
Wegelin et al. (1987). Particle analysis reviewed by Boller indicates
that after seven days of operation, the four stage pilot filter
utilized by Wegelin et al. (1987) removed more than 98 percent of
particles sized 1.1 [mu]m, and greater than 99 percent of particles
sized 3.6 [mu]m. After 62 days, only 80 percent of particles sized 1.1
[mu]m were removed, while 90 percent of particles sized 3.6 [mu]m were
removed. Boller did not give the solids loading on the tested filter,
and particle removal was not correlated to Cryptosporidium oocyst
removal.
Collins et al. (1994) investigated solids and algae removal with
pilot scale vertical downflow roughing filters. Gravel media size,
filter depth, and flow rate were varied to determine which design
variables had the greatest effect on filter performance. Results
indicated that the most influential design parameters for removing
solids from water, in order of importance, were filter length, gravel
size, and hydraulic flow rate. For algae removal, the most influential
design parameters were hydraulic flow rate, filter length, and gravel
size. Solids removal was better in filters that had been ripened with
algae for 5-7 days. However, extrapolation of these results to
Cryptosporidium removal could not be made.
c. Request for comment. The Agency requests comment on the
information that has been presented about roughing filters, and
specifically the question of whether and under what conditions roughing
filters should be awarded a 0.5 log credit for removal of
Cryptosporidium. EPA also requests information on specific studies of
Cryptosporidium oocyst removal by roughing filters, or from studies of
the removal of surrogate parameters that have been shown to correlate
with oocyst removal in roughing filters.
10. Slow Sand Filtration
a. What is EPA proposing today? Slow sand filtration is defined in
40 CFR 141.2 as a process involving passage of raw water through a bed
of sand at low velocity (generally less than 0.4 m/h) resulting in
substantial particulate removal by physical and biological mechanisms.
Today's proposal allows systems using slow sand filtration as a
secondary filtration step following a primary filtration process (e.g.,
conventional treatment) to receive an additional 2.5 log
Cryptosporidium treatment credit. There must be no disinfectant
residual in the influent water to the slow sand filtration process to
be eligible for credit.
Note that this proposed credit differs from the credit proposed for
slow sand filtration as a primary filtration process. EPA has
concluded, based on treatment studies described in section III.D, that
plants using well designed and well operated slow sand filtration as a
primary filtration process can achieve an average Cryptosporidium
removal of 3 log (Schuler and Ghosh, 1991, Timms et al. 1995, Hall et
al. 1994). Consequently, as described in section IV.A, EPA is proposing
that plants using slow sand filtration as a primary filtration process
receive a 3 log credit towards Cryptosporidium treatment requirements
associated with Bins 2-4 under the LT2ESWTR (i.e., credit equivalent to
a conventional treatment plant).
The proposed 2.5 log credit for slow sand filtration as part of the
microbial toolbox applies only when it is used as a secondary
filtration step, following a primary filtration process like
conventional treatment. While the removal mechanisms that make slow
sand filtration effective as a primary filtration process would also be
operative when used as a secondary filtration step, EPA has little data
on this specific application. The Agency is proposing 2.5 log credit
for slow sand filtration as a secondary filtration step, in comparison
to 3 log credit as a primary filtration process, as a conservative
measure reflecting greater uncertainty. In addition, the proposed 2.5
log credit for slow sand filtration as part of the microbial toolbox is
consistent with the recommendation in the Stage 2 M-DBP Agreement in
Principle.
b. How was this proposal developed? The Stage 2 M-DBP Agreement in
Principle recommends that slow sand filtration receive 2.5 log or
greater Cryptosporidium treatment credit when used in addition to
existing treatment that achieves compliance with the

[[Page 47702]]

IESWTR or LT1ESWTR. Slow sand filtration is not typically used as a
secondary filtration step following conventional treatment or other
primary filtration processes of similar efficacy. However, EPA expects
that slow sand filtration would achieve significant removal of
Cryptosporidium in such a treatment train.
While there is a significant body of data demonstrating the
effectiveness of slow sand filtration for Cryptosporidium removal as a
primary filtration process, as described in section III.D, EPA has
limited data on the effectiveness of slow sand filtration when used as
a secondary filtration step. Hall et al. (1994) evaluated oocyst
removal for a pilot scale slow sand filter following a primary
filtration process identified as a rapid gravity filter. The combined
treatment train of a primary filtration process followed by slow sand
filtration achieved greater than 3 log Cryptosporidium removal in three
of five experimental runs, while approximately 2.5 log reduction was
observed in the other two runs. In comparison, Hall et al. (1994)
reported slow sand filtration alone to achieve at least a 3 log removal
of oocysts in each of four experimental runs when not preceded by a
primary filtration process. The authors offered no explanation for
these results, but measured oocyst removals may have been impacted by
limitations with the analytical method.
Removal of microbial pathogens in slow sand filters is complex and
is believed to occur through a combination of physical, chemical, and
biological mechanisms, both on the surface (schmutzdecke) and in the
interior of the filter bed. It is unknown if the higher quality of the
water that would be influent to a slow sand filter when used as a
secondary filtration step would impact the efficiency of the filter in
removing Cryptosporidium. Based on the limited data on the performance
of slow sand filtration as a secondary filtration step, and in
consideration of the recommendation of the Advisory Committee, EPA is
proposing only a 2.5 log additional Cryptosporidium treatment credit
for this application.
c. Request for comment. The Agency requests comment on whether the
available data are adequate to support awarding a 2.5 log
Cryptosporidium removal credit for slow sand filtration applied as a
secondary filtration step, along with any additional information
related to this application.
11. Membrane Filtration
a. What is EPA proposing today? EPA is proposing criteria for
awarding credit to membrane filtration processes for removal of
Cryptosporidium. To receive removal credit, the membrane filtration
process must: (1) Meet the basic definition of a membrane filtration
process, (2) have removal efficiency established through challenge
testing and verified by direct integrity testing, and (3) undergo
periodic direct integrity testing and continuous indirect integrity
monitoring during use. The maximum removal credit that a membrane
filtration process is eligible to receive is equal to the lower value
of either:

--The removal efficiency demonstrated during challenge testing OR
--The maximum log removal value that can be verified through the direct
integrity test (i.e., integrity test sensitivity) used to monitor the
membrane filtration process.

By the criteria in today's proposal, a membrane filtration process
could potentially meet the Bin 4 Cryptosporidium treatment requirements
of this proposal. These criteria are described in more detail below.
EPA is developing a Membrane Filtration Guidance Manual that provides
additional information and procedures for meeting these criteria (USEPA
2003e). A draft of this guidance is available in the docket for today's
proposal (http://www.epa.gov/edocket/).
Definition of a Membrane Filtration Process
For the purpose of this proposed rule, membrane filtration is
defined as a pressure or vacuum driven separation process in which
particulate matter larger than 1 [mu]m is rejected by a nonfibrous,
engineered barrier, primarily through a size exclusion mechanism, and
which has a measurable removal efficiency of a target organism that can
be verified through the application of a direct integrity test. This
definition is intended to include the common membrane technology
classifications: microfiltration (MF), ultrafiltration (UF),
nanofiltration (NF), and reverse osmosis (RO). MF and UF are low-
pressure membrane filtration processes that are primarily used to
remove particulate matter and microbial contaminants. NF and RO are
membrane separation processes that are primarily used to remove
dissolved contaminants through a variety of mechanisms, but which also
remove particulate matter via a size exclusion mechanism.
In today's proposal, the critical distinction between membrane
filtration processes and bag and cartridge filters, described in
section IV.C.12, is that the integrity of membrane filtration processes
can be directly tested. Based on this distinction, EPA is proposing
that membrane material configured into a cartridge filtration device
that meets the definition of membrane filtration and that can be direct
integrity tested according to the criteria specified in this section is
eligible for the same removal credit as a membrane filtration process.
Membrane devices can be designed in a variety of configurations
including hollow-fiber modules, hollow-fiber cassettes, spiral-wound
elements, cartridge filter elements, plate and frame modules, and
tubular modules among others. In today's proposal, the generic term
module is used to refer to all of these various configurations and is
defined as the smallest component of a membrane unit in which a
specific membrane surface area is housed in a device with a filtrate
outlet structure. A membrane unit is defined as a group of membrane
modules that share common valving that allows the unit to be isolated
from the rest of the system for the purpose of integrity testing or
other maintenance.
Challenge Testing
A challenge test is defined as a study conducted to determine the
removal efficiency (i.e., log removal value) of the membrane filtration
media. The removal efficiency demonstrated during challenge testing
establishes the maximum removal credit that a membrane filtration
process is eligible to receive, provided this value is less than or
equal to the maximum log removal value that can be verified by the
direct integrity test (as described in the following subsection).
Challenge testing is a product specific rather than a site specific
requirement. At the discretion of the State, data from challenge
studies conducted prior to promulgation of this regulation may be
considered in lieu of additional testing. However, the prior testing
must have been conducted in a manner that demonstrates a removal
efficiency for Cryptosporidium commensurate with the treatment credit
awarded to the process. Guidance for conducting challenge testing to
meet the requirements of the rule is provided in the Membrane
Filtration Guidance Manual (USEPA 2003e). Challenge testing must be
conducted according to the following criteria:
? Challenge testing must be conducted on a full-scale
membrane module identical in material and construction to the membrane
modules proposed for use in full-scale treatment facilities.
Alternatively, challenge testing may be conducted on a smaller membrane
module, identical in material and similar in construction to the full-

[[Page 47703]]

scale module, if testing meets the other requirements listed in this
section.
? Challenge testing must be conducted using Cryptosporidium
oocysts or a surrogate that has been determined to be removed no more
efficiently than Cryptosporidium oocysts. The organism or surrogate
used during challenge testing is referred to as the challenge
particulate. The concentration of the challenge particulate must be
determined using a method capable of discretely quantifying the
specific challenge particulate used in the test. Thus, gross water
quality measurements such as turbidity or conductivity cannot be used.
? The maximum allowable feed water concentration used during
a challenge test is based on the detection limit of the challenge
particulate in the filtrate, and is determined according to the
following equation:

Maximum Feed Concentration = 3.16 x 10\6\ x (Filtrate Detection Limit)

This will allow the demonstration of up to 6.5 log removal during
challenge testing if the challenge particulate is removed to the
detection limit.
? Challenge testing must be conducted under representative
hydraulic conditions at the maximum design flux and maximum design
system recovery as specified by the manufacturer. Flux is defined as
the flow per unit of membrane area. Recovery is defined as the ratio of
filtrate volume produced by a membrane to feed water volume applied to
a membrane over the course of an uninterrupted operating cycle. An
operating cycle is bounded by two consecutive backwash or cleaning
events. In the context of this rule, recovery does not consider losses
that occur due to the use of filtrate in backwashing or cleaning
operations.
? Removal efficiency of a membrane filtration process is
determined from the results of the challenge test, and expressed in
terms of log removal values as defined by the following equation:

LRV = LOG₁₀(C_f)-LOG₁₀(C_p)

where LRV = log removal value demonstrated during challenge testing;
C_f = the feed concentration used during the challenge test;
and C_p = the filtrate concentration observed during the
challenge test. For this equation to be valid, equivalent units must be
used for the feed and filtrate concentrations. If the challenge
particulate is not detected in the filtrate, then the term
C_p is set equal to the detection limit. A single LRV is
calculated for each membrane module evaluated during the test.
? The removal efficiency of a membrane filtration process
demonstrated during challenge testing is expressed as a log removal
value (LRV_C-Test). If fewer than twenty modules are tested,
then LRV_C-Test is assigned a value equal to the lowest of
the representative LRVs among the various modules tested. If twenty or
more modules are tested, then LRV_C-Test is assigned a value
equal to the 10th percentile of the representative LRVs among the
various modules tested. The percentile is defined by [i/(n+1)]
where i
is the rank of n individual data points ordered lowest to highest. It
may be necessary to calculate the 10th percentile using linear
interpolation.
? A quality control release value (QCRV) must be established
for a non-destructive performance test (e.g., bubble point test,
diffusive airflow test, pressure/vacuum decay test) that demonstrates
the Cryptosporidium removal capability of the membrane module. The
performance test must be applied to each production membrane module
that did not undergo a challenge test in order to verify
Cryptosporidium removal capability. Production membrane modules that do
not meet the established QCRV are not eligible for the removal credit
demonstrated during challenge testing.
? Any significant modification to the membrane filtration
device (e.g., change in the polymer chemistry of the membrane) requires
additional challenge testing to demonstrate removal efficiency of the
modified module and to define a new QCRV for the nondestructive
performance test.
Direct Integrity Testing
In order to receive removal credit for Cryptosporidium, the removal
efficiency of a membrane filtration process must be routinely verified
through direct integrity testing. A direct integrity test is defined as
a physical test applied to a membrane unit in order to identify and
isolate integrity breaches. An integrity breach is defined as one or
more leaks that could result in contamination of the filtrate. The
direct integrity test method must be applied to the physical elements
of the entire membrane unit including membranes, seals, potting
material, associated valving and piping, and all other components which
under compromised conditions could result in contamination of the
filtrate.
The direct integrity tests commonly used at the time of this
proposal include those that use an applied pressure or vacuum (such as
the pressure decay test and diffusive airflow test), and those that
measure the rejection of a particulate or molecular marker (such as
spiked particle monitoring). Today's proposal does not stipulate the
use of a particular direct integrity test. Instead, the direct
integrity test must meet performance criteria for resolution,
sensitivity, and frequency.
Resolution is defined as the smallest leak that contributes to the
response from a direct integrity test. Any direct integrity test
applied to meet the requirements of this proposed rule must have a
resolution of 3 [mu]m or less. The manner in which the resolution
criterion is met will depend on the type of direct integrity test used.
For example, a pressure decay test can meet the resolution criterion by
applying a net test pressure great enough to overcome the bubble point
of a 3 [mu]m hole. A direct integrity test that uses a particulate or
molecular marker can meet the resolution criterion by applying a marker
of 3 [mu]m or smaller.
Sensitivity is defined as the maximum log removal value that can be
reliably verified by the direct integrity test (LRV_DIT). The
sensitivity of the direct integrity test applied to meet the
requirements of this proposed rule must be equal to or greater than the
removal credit awarded to the membrane filtration process. The manner
in which LRV_DIT is determined will depend on the type of
direct integrity test used. Direct integrity tests that use an applied
pressure or vacuum typically measure the rate of pressure/vacuum decay
or the flow of air through an integrity breach. The response from this
type of integrity test can be related to the flow of water through an
integrity breach (Q_breach) during normal operation, using
procedures such as those described in the Membrane Filtration Guidance
Manual (USEPA 2003e). Once Q_breach has been determined, a
simple dilution model is used to calculate LRV_DIT for the
specific integrity test application, as shown by the following
equation:

LRV_DIT = LOG₁₀(Q_p/(VCF x
Q_breach))

where LRV_DIT = maximum log removal value that can be
verified by a direct integrity test; Q_p = total design
filtrate flow from the membrane unit; Q_breach = flow of
water from an integrity breach associated with the smallest integrity
test response that can be reliably measured; and VCF = volumetric
concentration factor.
The volumetric concentration factor is the ratio of the suspended
solids concentration on the high pressure side of the membrane relative
to the feed water, and is defined by the following equation:

VCF = C_m/C_f

where C_m is the concentration of particulate matter on the
high pressure

[[Page 47704]]

side of the membrane that remains in suspension; and C_f is
the concentration of suspended particulate matter in the feed water.
The magnitude of the concentration factor depends on the mode of system
operation and typically ranges from 1 to 20. The Membrane Filtration
Guidance Manual presents approaches for determining the volumetric
concentration factor for different operating modes (USEPA 2003e).
Sensitivity of direct integrity tests that use a particulate or
molecular marker is determined from the feed and filtrate
concentrations of the marker. The LRV_DIT for this type of
direct integrity test is calculated according to the following
equation:

LRV_DIT = LOG₁₀(C_f) -
LOG₁₀(C_p)

where LRV_DIT = maximum log removal value that can be
verified by a direct integrity test; C_f = the typical feed
concentration of the marker used in the test; and C_p = the
filtrate concentration of the marker from an integral membrane unit.
For this equation to be valid, equivalent units must be used for the
feed and filtrate concentrations. An ideal particulate or molecular
marker would be completely removed by an integral membrane unit.
If the sensitivity of the direct integrity test is such that
LRV_DIT is less than LRV_C-Test, LRV_DIT
establishes the maximum removal credit that a membrane filtration
process is eligible to receive. Conversely, if LRV_DIT for a
direct integrity test is greater than LRV_C-Test,
LRV_C-Test establishes the maximum removal credit.
A control limit is defined as an integrity test response which, if
exceeded, indicates a potential problem with the system and triggers a
response. Under this proposal, a control limit for a direct integrity
test must be established that is indicative of an integral membrane
unit capable of meeting the Cryptosporidium removal credit awarded by
the State. If the control limit for the direct integrity test is
exceeded, the membrane unit must be taken off-line for diagnostic
testing and repair. The membrane unit could only be returned to service
after the repair has been completed and confirmed through the
application of a direct integrity test.
The frequency of direct integrity testing specifies how often the
test is performed over an established time interval. Most direct
integrity tests available at the time of this proposal are applied
periodically and must be conducted on each membrane unit at a frequency
of not less than once every 24 hours while the unit is in operation. If
continuous direct integrity test methods become available that also
meet the sensitivity and resolution criteria described earlier, they
may be used in lieu of periodic testing.
EPA is proposing that at a minimum, a monthly report must be
submitted to the State summarizing all direct integrity test results
above the control limit associated with the Cryptosporidium removal
credit awarded to the process and the corrective action that was taken
in each case.
Continuous Indirect Integrity Monitoring
The majority of currently available direct integrity test methods
are applied periodically since the membrane unit must be taken out of
service to conduct the test. In order to provide some measure of
process performance between direct integrity testing events, continuous
indirect integrity monitoring is required. Indirect integrity
monitoring is defined as monitoring some aspect of filtrate water
quality that is indicative of the removal of particulate matter. If a
continuous direct integrity test is implemented that meets the
resolution and sensitivity criteria described previously, continuous
indirect integrity monitoring is not required. Continuous indirect
integrity monitoring must be conducted according to the following
criteria:
? Unless the State approves an alternative parameter,
continuous indirect integrity monitoring must include continuous
filtrate turbidity monitoring.
? Continuous monitoring is defined as monitoring conducted at
a frequency of no less than once every 15 minutes.
? Continuous monitoring must be separately conducted on each
membrane unit.
? If indirect integrity monitoring includes turbidity and if
the filtrate turbidity readings are above 0.15 NTU for a period greater
than 15 minutes (i.e., two consecutive 15-minute readings above 0.15
NTU), direct integrity testing must be performed on the associated
membrane units.
? If indirect integrity monitoring includes a State-approved
alternative parameter and if the alternative parameter exceeds a State-
approved control limit for a period greater than 15 minutes, direct
integrity testing must be performed on the associated membrane units.
? EPA is proposing that at a minimum, a monthly report must
be submitted to the primacy agency summarizing all indirect integrity
monitoring results triggering direct integrity testing and the
corrective action that was taken in each case.
b. How was this proposal developed? The Stage 2 M-DBP Agreement in
Principle recommends that EPA develop criteria to award Cryptosporidium
removal credit to membrane filtration processes. Today's proposal and
the supporting guidance are consistent with the Agreement.
A number of studies have been conducted which have demonstrated the
ability of membrane filtration processes to remove pathogens, including
Cryptosporidium, to below detection levels. A literature review
summarizing the results of several comprehensive studies was conducted
by EPA and is presented in Low-Pressure Membrane Filtration for
Pathogen Removal: Application, Implementation, and Regulatory Issues
(USEPA 2001h). Many of these studies used Cryptosporidium seeding to
demonstrate removal efficiencies as high as 7 log. The collective
results from these studies demonstrate that an integral membrane
module, i.e., a membrane module without any leaks or defects, with an
exclusion characteristic smaller than Cryptosporidium, is capable of
removing this pathogen to below detection in the filtrate, independent
of the feed concentration.
Some filtration devices have used membrane media in a cartridge
filter configuration; however, few data are available documenting their
ability to meet the requirements for membrane filtration described in
section IV.C.11.a of this preamble. However, in one study reported by
Dwyer et al. (2001), a membrane cartridge filter demonstrated
Cryptosporidium removal efficiencies in excess of 6 log. This study
illustrates the potentially high removal capabilities of membrane
filtration media configured into a cartridge filtration device, thus
providing a basis for awarding removal credits to these devices under
the membrane filtration provision of the rule, assuming that the device
meets the definition of a membrane filtration process as well as the
direct integrity test requirements.
Today's proposal requires challenge testing of membrane filtration
processes used to remove Cryptosporidium. As noted in section III.D,
EPA believes this is necessary due to the proprietary nature of these
systems and the lack of any uniform criteria for establishing the
exclusion characteristic of a membrane. Challenge testing addresses the
lack of a standard approach for characterizing membranes by requiring
direct verification of removal efficiency. The proposed challenge
testing is product-specific and not site-specific since the

[[Page 47705]]

intent of this testing is to demonstrate the removal capabilities of
the membrane product rather than evaluate the feasibility of
implementing membrane treatment at a specific plant.
Testing can be conducted using a full-scale module or a smaller
module if the results from the small-scale module test can be related
to full-scale module performance. Most challenge studies presented in
the literature have used full-scale modules, which provide results that
can be directly related to full-scale performance. However, use of
smaller modules is considered feasible in the evaluation of removal
efficiency, and a protocol for challenge testing using small-scale
modules has been proposed (NSF, 2002a). Since the removal efficiency of
an integral membrane is a direct function of the membrane material, it
may be possible to use a small-scale module containing the same
membrane fibers or sheets used in full-scale modules for this
evaluation. However, it will be necessary to relate the results of the
small-scale module test to the nondestructive performance test quality
control release value that will be used to validate full-scale
production modules.
Challenge testing with either Cryptosporidium oocysts or a
surrogate is permitted. Challenge testing with Cryptosporidium clearly
provides direct verification of removal efficiency for this pathogen;
however, several studies have demonstrated that surrogates can provide
an accurate or conservative measure of Cryptosporidium removal
efficiency. Since removal of particulate matter larger than 1 [mu]m by
a membrane filtration process occurs primarily via a size exclusion
mechanism, the shape and size distribution of the surrogate must be
selected such that the surrogate is not removed to a greater extent
than the target organism. Surrogates that have been successfully used
in challenge studies include polystyrene microspheres and bacterial
endospores. The bacterial endospore, Bacillus subtilis, has been used
as a surrogate for Cryptosporidium oocysts during challenge studies
evaluating pathogen removal by physical treatment processes, including
membrane filtration (Rice et al. 1996, Fox et al. 1998, Trimboli et al.
1999, Owen et al, 1999). Studies evaluating cartridge filters have
demonstrated that polystyrene microspheres can provide an accurate or
conservative measure of removal efficiency (Long, 1983, Li et al.
1997). Furthermore, the National Sanitation Foundation (NSF)
Environmental Technology Verification (ETV) protocol for verification
testing for physical removal of microbiological and particulate
contaminants specifies the use of polymeric microspheres of a known
size distribution (NSF 2002b). Guidance on selection of an appropriate
surrogate for establishing a removal efficiency for Cryptosporidium
during challenge testing is presented in the Membrane Filtration
Guidance Manual (USEPA 2003e).
The design of the proposed challenge studies is similar to the
design of the seeding studies described in the literature cited
earlier. Seeding studies are used to challenge the membrane module with
pathogen levels orders of magnitude higher than those encountered in
natural waters. However, elevated feed concentrations can lead to
artificially high estimates of removal efficiency. To address this
issue, the feed concentration applied to the membrane during challenge
studies is capped at a level that will allow the demonstration of up to
6.5 log removal efficiency if the challenge particulate is removed to
the detection level.
Because challenge testing with Cryptosporidium or a surrogate is
not conducted on every membrane module, it is necessary to establish
criteria for a non-destructive performance test that can be applied to
all production membrane modules. Results from a non-destructive test,
such as a bubble point test, that are correlated with the results of
challenge testing can be used to establish a quality control release
value (QCRV) that is indicative of the ability of a membrane filtration
process to remove Cryptosporidium. The non-destructive test and QCRV
can be used to verify the Cryptosporidium removal capability of modules
that are not challenge tested. Most membrane manufacturers have already
adapted some form of non-destructive testing for product quality
control purposes and have established a quality control release value
that is indicative of an acceptable product. It may be possible to
apply these existing practices for the purpose of verifying the
capability of a membrane filtration process to remove Cryptosporidium.
Challenge testing provides a means of demonstrating the removal
efficiency of an integral membrane module; however, defects or leaks in
the membrane or other system components can result in contamination of
the filtrate unless they are identified, isolated, and repaired. In
order to verify continued performance of a membrane system, today's
proposal requires direct integrity testing of membrane filtration
processes used to meet Cryptosporidium treatment requirements. Direct
integrity testing is required because it is a test applied to the
physical membrane module and, thus, a direct evaluation of integrity.
Furthermore, direct integrity methods are the most sensitive integrity
monitoring methods commonly used at the time of this proposal (Adham et
al. 1995).
The most common direct integrity tests apply a pressure or a vacuum
to one side of a fully wetted membrane and monitor either the pressure
decay or the volume of displaced fluid over time. However, the
proprietary nature of these systems makes it impractical to define a
single direct integrity test methodology that is applicable to all
existing and future membrane products. Therefore, performance criteria
have been established for any direct integrity test methodology used to
verify the removal efficiency of a membrane system. These performance
criteria are resolution, sensitivity, and frequency.
As stated previously, the resolution of an integrity test refers to
the smallest leak that contributes to the response from an integrity
test. For example, in a pressure decay integrity test, resolution is
the smallest leak that contributes to pressure loss during the test.
Today's proposal specifies a resolution of 3 [mu]m or less, which is
based on the size of Cryptosporidium oocysts. This requirement ensures
that a leak that could pass a Cryptosporidium oocyst would contribute
to the response from an integrity test.
The sensitivity of an integrity test refers to the maximum log
removal that can be reliably verified by the test. Again using the
pressure decay integrity test as an example, the method sensitivity is
a function of the smallest pressure loss that can be detected over a
membrane unit. Today's proposal limits the log removal credit that a
membrane filtration process is eligible to receive to the maximum log
removal value that can be verified by a direct integrity test.
In order to serve as a useful process monitoring tool for assuring
system integrity, it is necessary to establish a site-specific control
limit for the integrity test that corresponds to the log removal
awarded to the process. A general approach for establishing this
control limit for some integrity test methods is presented in guidance;
however, the utility will need to work with the membrane manufacturer
and State to establish a site-specific control limit appropriate for
the integrity test used and level of credit awarded. Excursions above
this limit indicate a potential integrity breach and would trigger
removal of the suspect unit from service followed by diagnostic testing
and subsequent repair, as necessary.

[[Page 47706]]

Most direct integrity tests available at the time of this proposal
must be applied periodically since it is necessary to take the membrane
unit out of service to conduct the test. Today's proposal establishes
the minimum frequency for performing a direct integrity test at once
per 24 hours. Currently, there is no standard frequency for direct
integrity testing that has been adopted by all States and membrane
treatment facilities. In a recent survey, the required frequency of
integrity testing was found to vary from once every four hours to once
per week; however, the most common frequency for conducting a direct
integrity test was once every 24 hours (USEPA 2001h). Specifically, 10
out of 14 States that require periodic direct integrity testing specify
a frequency of once every 24 hours. Furthermore, many membrane
manufacturers of systems with automated integrity test systems set up
the membrane units to automatically perform a direct integrity test
once per 24 hours. EPA has concluded that the 24 hour direct integrity
test frequency ensures that removal efficiency is verified on a routine
basis without resulting in excessive system downtime.
Since most direct integrity tests are applied periodically, it is
necessary to implement some level of continuous monitoring to assess
process performance between direct integrity test events. In the
absence of a continuous direct integrity test, continuous indirect
integrity monitoring is required. Although it has been shown that
commonly used indirect integrity monitoring methods lack the
sensitivity to detect small integrity breaches that are of concern
(Adham et al. 1995), they can detect large breaches and provide some
assurance that a major failure has not occurred between direct
integrity test events. Turbidity monitoring is proposed as the method
of indirect integrity monitoring unless the State approves an alternate
approach. Available data indicate that an integral membrane filtration
process can consistently produce water with a turbidity less than 0.10
NTU, regardless of the feedwater quality. Consequently, EPA is
proposing that exceedance of a filtrate turbidity value of 0.15 NTU
triggers direct integrity testing to verify and isolate the integrity
breach.
c. Request for comment. EPA requests comment on the following
issues:
? EPA is proposing to include membrane cartridge filters that
can be direct integrity tested under the definition of a membrane
filtration process since one of the key differences between membrane
filtration processes and bag and cartridge filters, within the context
of this regulation, is the applicability of direct integrity test
methods to the filtration process. EPA requests comment on the
inclusion of membrane cartridge filters that can be direct integrity
tested under the definition of a membrane filtration process in this
rule.
? The applicability of the proposed Cryptosporidium removal
credits and performance criteria to Giardia lamblia.
? Appropriate surrogates, or the characteristics of
appropriate surrogates, for use in challenge testing. EPA requests data
or information demonstrating the correlation between removal of a
proposed surrogate and removal of Cryptosporidium oocysts.
? The use of a non-destructive performance test and
associated quality control release values for demonstrating the
Cryptosporidium removal capability of membrane modules that are not
directly challenge tested.
? The appropriateness of the minimum direct integrity test
frequency of once per 24 hours.
? The proposed minimum reporting frequency for direct
integrity testing results above the control limit and indirect
integrity monitoring results that trigger direct integrity monitoring.
12. Bag and Cartridge Filtration
a. What is EPA proposing today? EPA is proposing criteria for
awarding Cryptosporidium removal credit of 1 log for bag filtration
processes and 2 log for cartridge filtration processes. To receive
removal credit the process must: (1) Meet the basic definition of a bag
or cartridge filter and (2) have removal efficiency established through
challenge testing.
Definition of a Bag or Cartridge Filter
For the purpose of this rule, bag and cartridge filters are defined
as pressure driven separation processes that remove particulate matter
larger than 1 [mu]m using an engineered porous filtration media through
either surface or depth filtration.
The distinction between bag filters and cartridge filters is based
on the type of filtration media used and the manner in which the
devices are constructed. Bag filters are typically constructed of a
non-rigid, fabric filtration media housed in a pressure vessel in which
the direction of flow is from the inside of the bag to outside.
Cartridge filters are typically constructed as rigid or semi-rigid,
self-supporting filter elements housed in pressure vessels in which
flow is from the outside of the cartridge to the inside.
Although all filters classified as cartridge filters share
similarities with respect to their construction, there are significant
differences among the various commercial cartridge filtration devices.
From a public health perspective, an important distinction among these
filters is the ability to directly test the integrity of the filtration
system in order to verify that there are no leaks that could result in
contamination of the filtrate. Any membrane cartridge filtration device
that can be direct integrity tested according to the criteria specified
in section IV.C.11.a is eligible for removal credit as a membrane,
subject to the criteria specified in that section. Section IV.C.12
applies to all bag filters, as well as to cartridge filters which
cannot be direct integrity tested.
Challenge Testing
In order to receive 1 log removal credit, a bag filter must have a
demonstrated removal efficiency of 2 log or greater for
Cryptosporidium. Similarly, to receive 2 log removal credit, a
cartridge filter must have a demonstrated removal efficiency of 3 log
or greater for Cryptosporidium. The 1 log factor of safety is applied
to the removal credit awarded to these filtration devices based on two
primary considerations. First, the removal efficiency of some bag and
cartridge filters has been observed to vary by more than 1 log over the
course of operation (Li et al. 1997, NSF 2001a, NSF 2001b). Second, bag
and cartridge filters are not routinely direct integrity tested during
operation in the field; hence, there is no means of verifying the
removal efficiency of filtration units during routine use. Based on
these considerations, a conservative approach to awarding removal
credit based on challenge test results is warranted.
Removal efficiency must be demonstrated through a challenge test
conducted on the bag or cartridge filter proposed for use in full-scale
drinking water treatment facilities for removal of Cryptosporidium.
Challenge testing is required for specific products and is not intended
to be site specific. At the discretion of the State, data from
challenge studies conducted prior to promulgation of this regulation
may be considered in lieu of additional testing. However, the prior
testing must have been conducted in a manner that demonstrates a
removal efficiency for Cryptosporidium commensurate with the treatment
credit awarded to the process. Guidance on conducting challenge studies
to demonstrate the Cryptosporidium removal efficiency of filtration
units is presented in the Membrane Filtration Guidance Manual (USEPA
2003e). Challenge testing must

[[Page 47707]]

be conducted according to the following criteria:
? Challenge testing must be conducted on a full-scale filter
element identical in material and construction to the filter elements
proposed for use in full-scale treatment facilities.
? Challenge testing must be conducted using Cryptosporidium
oocysts or a surrogate which is removed no more efficiently than
Cryptosporidium oocysts. The organism or surrogate used during
challenge testing is referred to as the challenge particulate. The
concentration of the challenge particulate must be determined using a
method capable of discretely quantifying the specific organism or
surrogate used in the test, i.e., gross water quality measurements such
as turbidity cannot be used.
? The maximum allowable feed water concentration used during
a challenge test is based on the detection limit of the challenge
particulate in the filtrate and calculated using one of the following
equations.
For bag filters:

Maximum Feed Concentration = 3.16 x 103 x (Filtrate
Detection Limit)
For cartridge filters:

Maximum Feed Concentration = 3.16 x 104 x (Filtrate
Detection Limit)

This will allow the demonstration of up to 3.5 log removal for bag
filters and 4.5 log removal for cartridge filters during challenge
testing if the challenge particulate is removed to the detection limit.
? Challenge testing must be conducted at the maximum design
flow rate specified by the manufacturer.
? Each filter must be tested for a duration sufficient to
reach 100% of the terminal pressure drop, a parameter specified by the
manufacturer which establishes the end of the useful life of the
filter. In order to achieve terminal pressure drop during the test, it
will be necessary to add particulate matter to the test solution, such
as fine carbon test dust or bentonite clay particles.
? Each filter must be challenged with the challenge
particulate during three periods over the filtration cycle: within 2
hours of start-up after a new bag or cartridge filter has been
installed, when the pressure drop is between 45 and 55% of the terminal
pressure drop, and at the end of the run after the pressure drop has
reached 100% of the terminal pressure drop.
? Removal efficiency of a bag or cartridge filtration process
is determined from the results of the challenge test, and expressed in
terms of log removal values as defined by the following equation:

LRV = LOG₁₀(C_f)-LOG₁₀(C_p)

Table IV-18.--Results From Studies of Cryptosporidium or Surrogate Removal by Bag and Cartridge Filters
----------------------------------------------------------------------------------------------------------------
Process Log removal Organism/surrogate Reference
----------------------------------------------------------------------------------------------------------------
Bag and cartridge filtration in 1.1 to 2.1............. 3 to 6 [mu]m spheres... NSF 2001a.
series.
Cartridge filtration................. 3.5 (average).......... Cryptosporidium........ Enriquez et al. 1999.
Cartridge filtration................. 3.3 (average).......... Cryptosporidium........ Roessler, 1998.
Cartridge filtration................. 1.1 to 3.3............. Cryptosporidium........ Schaub et al. 1993.
Cartridge filtration................. 0.5 to 3.6............. 5.7 [mu]m spheres...... Long, 1983.
Cartridge filtration................. 2.3 to 2.8............. Cryptosporidium........ Ciardelli, 1996a.
Cartridge filtration................. 2.7 to 3.7............. Cryptosporidium........ Ciardelli, 1996b.
Prefilter and bag filter in series... 1.9 to 3.2............. 3.7 [mu]m spheres...... NSF 2001b.
Bag filtration....................... [sim]3.0............... Cryptosporidium........ Cornwell and
LeChevallier, 2002.
Bag filtration....................... 0.5 to 3.6............. Cryptosporidium........ Li et al. 1997.
Bag filtration....................... 0.5 to 2.0............. 4.5 [mu]m spheres...... Goodrich et al. 1995.
----------------------------------------------------------------------------------------------------------------

These data demonstrate highly variable removal performance for
these processes, ranging from 0.5 log to 3.6 log for both bag and
cartridge filtration. Results of these studies also show no correlation
between the pore size rating established by the manufacturer and the
removal efficiency of a filtration device. In a study evaluating two
cartridge filters, both with a pore size rating of 3 [mu]m, a 2 log
difference in Cryptosporidium oocyst removal was observed between the
two filters (Schaub et al. 1993). Another study evaluated seventeen
cartridge filters with a range of pore size ratings from 1 [mu]m to 10
[mu]m and found no correlation with removal efficiency (Long, 1983). Li
et al. (1997) evaluated three bag filters with similar pore size
ratings and observed a 3 log difference in

[[Page 47708]]

Cryptosporidium oocyst removal among them. These results indicate that
bag and cartridge filters may be capable of achieving removal of
oocysts in excess of 3 log; however, performance can vary significantly
among products and there appears to be no correlation between pore size
rating and removal efficiency.
Based on available data, specific design criteria that correlate to
removal efficiency cannot be derived for bag and cartridge filters.
Furthermore, the removal efficiency of these proprietary devices can be
impacted by product variability, increasing pressure drop over the
filtration cycle, flow rate, and other operating conditions. The data
in Table IV-18 were generated from studies performed under a variety of
operating conditions, many of which could not be considered
conservative (or worst-case) operation. These considerations lead to
the proposed challenge testing requirements which are intended to
establish a product-specific removal efficiency.
The proposed challenge testing is product-specific and not site-
specific since the intent of this testing is to demonstrate the removal
capabilities of the filtration device rather than evaluate the
feasibility of implementing the technology at a specific plant.
Challenge testing must be conducted using full-scale filter elements in
order to evaluate the performance of the entire unit, including the
filtration media, seals, filter housing and other components integral
to the filtration system. This will improve the applicability of
challenge test results to full-scale performance. Multiple filters of
the same type can be tested to provide a better statistical basis for
estimating removal efficiency.
Either Cryptosporidium oocysts or a suitable surrogate could be
used as the challenge particulate during the test. Challenge testing
with Cryptosporidium provides direct verification of removal
efficiency; however, some studies have demonstrated that surrogates,
such as polystyrene microspheres, can provide an accurate or
conservative measure of removal efficiency (Long 1983, Li et al. 1997).
Furthermore, the National Sanitation Foundation (NSF) Environmental
Technology Verification (ETV) protocol for verification testing for
physical removal of microbiological and particulate contaminants
specifies the use of polymeric microspheres of a known size
distribution (NSF 2002b). Guidance on selection of an appropriate
surrogate for establishing a removal efficiency for Cryptosporidium
during challenge testing is presented in the Membrane Filtration
Guidance Manual (USEPA 2003e).
In order to demonstrate a removal efficiency of at least 2 or 3 log
for bag or cartridge filters, respectively, it will likely be necessary
to seed the challenge particulate into the test solution. A criticism
of published studies that use this approach is that the seeded levels
are orders of magnitude higher than those encountered in natural waters
and this could potentially lead to artificially high estimates of
removal efficiency. To address this issue, the feed concentration
applied to the filter during challenge studies is capped at a level
that will allow the demonstration of a removal efficiency up to 4.5 log
for cartridge filters and 3.5 log for bag filters if the challenge
particulate is removed to the detection level.
The removal efficiency of some bag and cartridge filtration devices
has been shown to decrease over the course of a filtration cycle due to
the accumulation of solids and resulting increase in pressure drop. As
an example, Li et al. (1997) observed that the removal of 4.5 [mu]m
microspheres by a bag filter decreased from 3.4 log to 1.3 log over the
course of a filtration cycle. Studies evaluating bag and cartridge
filtration under the NSF ETV program have also shown a degradation in
removal efficiency over the course of the filtration cycle (NSF 2001a
and 2001b). In order to evaluate this potential variability, the
challenge studies are designed to assess removal efficiency during
three periods of a filtration cycle: within two hours of startup
following installation of a new filter, between 45% and 55% of terminal
pressure drop, and at the end of the run after 100% of terminal
pressure drop is realized.
Although challenge testing can provide an estimate of removal
efficiency for a bag or cartridge filtration process, it is not
feasible to conduct a challenge test on every production filter. This,
coupled with variability within a product line, could result in some
production filters that do not meet the removal efficiency demonstrated
during challenge testing. For membrane filtration processes, this
problem is addressed through the use of a quality control release value
established for a non-destructive test, such as a bubble point test or
pressure hold test, that is correlated to removal efficiency. Since the
non-destructive test can be applied to all production membrane modules,
this provides a feasible means of verifying the performance of every
membrane module used by a PWS. However, the non-destructive tests
applied to membrane filtration processes cannot be applied to most bag
and cartridge filtration devices, and EPA is not aware of an
alternative non-destructive test that can be used with these devices.
Typical process monitoring for bag and cartridge filtration systems
includes turbidity and pressure drop to determine when filters must be
replaced. However, the applicability of either of these process
monitoring parameters as tools for verifying removal of Cryptosporidium
has not been demonstrated. Only a few bag or cartridge filtration
studies have attempted to correlate turbidity removal with removal of
Cryptosporidium oocysts or surrogates. Li et al. (1997) found that the
removal efficiency for turbidity was consistently lower than removal
efficiency for oocysts or microspheres for the three bag filters
evaluated. Furthermore, none of the filters was capable of consistently
producing a filtered water turbidity below 0.3 NTU for the waters
evaluated. The contribution to turbidity from particles much smaller
than Cryptosporidium oocysts, and much smaller than the mesh size of
the filter, make it difficult to correlate removal of turbidity with
removal of Cryptosporidium. Consequently, EPA is proposing a 1 log
factor of safety to be applied to challenge test results in awarding
treatment credit to bag and cartridge filters, and is not proposing
integrity monitoring requirements for these devices.
c. Request for comment. EPA requests comment on the following
issues concerning bag and cartridge filters:
? The performance of bag and cartridge filters in removing
Cryptosporidium through all differential pressure ranges in a filter
run--EPA requests laboratory and field data, along with associated
quality assurance and quality control information, that will support a
determination of the appropriate level of Cryptosporidium removal
credit to award to these technologies.
? The performance of bag and cartridge filters in removing
Cryptosporidium when used in series with other bag or cartridge
filters--EPA requests laboratory and field data, along with associated
quality assurance and quality control information, that will support a
determination of the appropriate level of Cryptosporidium removal
credit to award to these technologies when used in series.
? Appropriate surrogates, or the characteristics of
appropriate surrogates, for use in challenge testing bag and cartridge
filters--EPA requests data or information demonstrating the correlation
between removal of a proposed surrogate and removal of Cryptosporidium
oocysts.

[[Page 47709]]

? The availability of non-destructive tests that can be
applied to bag and cartridge filters to verify the removal efficiency
of production filters that are not directly challenge tested--EPA
requests data or information demonstrating the correlation between a
proposed non-destructive test and the removal of Cryptosporidium
oocysts.
? The applicability of pressure drop monitoring, filtrate
turbidity monitoring, or other process monitoring and process control
procedures to verify the integrity of bag and cartridge filters--EPA
requests data or information demonstrating the correlation between a
proposed process monitoring tool and the removal of Cryptosporidium
oocysts.
? The applicability of bag and cartridge filters to different
source water types and treatment scenarios.
? The applicability of the proposed Cryptosporidium removal
credits and testing criteria to Giardia lamblia.
? The use of a 1 log factor of safety for awarding credit to
bag and cartridge filters--EPA requests comment on whether this is an
appropriate factor of safety to account for the inability to conduct
integrity monitoring of these devices, as well as the variability in
removal efficiency observed over the course of a filtration cycle for
some filtration devices. This inability creates uncertainty regarding
both changes in the performance of a given filter during use and
variability in performance among filters in a given product line. If
the 1 log factor of safety is higher than necessary to account for
these factors, should the Agency establish a lower value, such as a 0.5
log factor of safety?
13. Secondary Filtration
a. What is EPA proposing today? Today's proposal allows systems
using a second filtration stage to receive an additional 0.5 log
Cryptosporidium removal credit. To be eligible for this credit, the
secondary filtration must consist of rapid sand, dual media, granular
activated carbon (GAC), or other fine grain media in a separate stage
following rapid sand or dual media filtration. A cap, such as GAC, on a
single stage of filtration will not qualify for this credit. In
addition, the first stage of filtration must be preceded by a
coagulation step, and both stages must treat 100% of the flow.
b. How was this proposal developed? Although not addressed in the
Agreement in Principle, EPA has determined that secondary filtration
meeting the criteria described in this section will achieve additional
removal of Cryptosporidium oocysts. Consequently, additional removal
credit may be appropriate. As reported in section III.D, many studies
have shown that rapid sand filtration preceded by coagulation can
achieve significant removal of Cryptosporidium (Patania et al. 1995,
Nieminski and Ongerth 1995, Ongerth and Pecoraro 1995, LeChevallier and
Norton 1992, LeChevallier et al. 1991, Dugan et al. 2001, Nieminski and
Bellamy 2000, McTigue et al. 1998, Patania et al. 1999, Huck et al.
2000, Emelko et al. 2000). While these studies evaluated only a single
stage of filtration, the same mechanisms of removal are expected to
occur in a second stage of granular media filtration.
EPA received data from the City of Cincinnati, OH, on the removal
of aerobic spores through a conventional treatment facility that
employs GAC contactors for DBP, taste, and odor control after rapid
sand filtration. As described previously, a number of studies (Dugan et
al. 2001, Emelko et al. 1999 and 2000, Yates et al. 1998, Mazounie et
al. 2000) have demonstrated that aerobic spores are a conservative
indicator of Cryptosporidium removal by granular media filtration when
preceded by coagulation.
During the period of 1999 and 2000, the mean values of reported
spore concentrations in the influent and effluent of the Cincinnati GAC
contactors were 35.7 and 6.4 cfu/100 mL, respectively, indicating an
average removal of 0.75 log across the contactors. Approximately 16% of
the GAC filtered water results were below detection limit (1 cfu/100
mL) so the actual log spore removal may have been greater than
indicated by these results.
In summary, studies in the cited literature demonstrate that a fine
granular media filter preceded by coagulation can achieve high levels
of Cryptosporidium removal. Data on increased removal resulting from a
second stage of filtration are limited, and there is uncertainty
regarding how effective a second stage of filtration will be in
reducing levels of microbial pathogens that are not removed by the
first stage of filtration. However, EPA has concluded that a secondary
filtration process can achieve 0.5 log or greater removal of
Cryptosporidium based on (1) the theoretical consideration that the
same mechanisms of pathogen removal will be operative in both a primary
and secondary filtration stage, and (2) data from the City of
Cincinnati showing aerobic spore removal in GAC contactors following
rapid sand filtration. Therefore, EPA believes it is appropriate to
propose 0.5 log additional Cryptosporidium treatment credit for systems
using secondary filtration which meets the criteria of this section.
c. Request for comment. The Agency requests comment on awarding a
0.5 log Cryptosporidium removal credit for systems using secondary
filtration, including the design and operational criteria required to
receive the log removal credit. EPA specifically requests comment on
the following issues:
? Should there be a minimum required depth for the secondary
filter (e.g., 24 inches) in order for the system to receive credit?
? Should systems be eligible to receive additional
Cryptosporidium treatment credit within the microbial toolbox for both
a second clarification stage (e.g., secondary filtration, second stage
sedimentation) and lower finished water turbidity, given that
additional particle removal achieved by the second clarification stage
will reduce finished water turbidity?
14. Ozone and Chlorine Dioxide
a. What is EPA proposing today? Similar to the methodology used for
estimating log inactivation of Giardia lamblia by various chemical
disinfectants in 40 CFR 141.74, EPA is proposing the CT concept for
estimating log inactivation of Cryptosporidium by chlorine dioxide or
ozone. In today's proposal, systems must determine the total
inactivation of Cryptosporidium each day the system is in operation,
based on the CT values in Table IV-19 for ozone and Table IV-20 for
chlorine dioxide. The parameters necessary to determine the total
inactivation of Cryptosporidium must be monitored as stated in 40 CFR
141.74(b)(3)(i), (iii), and (iv), which is as follows:
? The temperature of the disinfected water must be measured
at least once per day at each residual disinfectant concentration
sampling point.
? The disinfectant contact time(s) (``T'') must be determined
for each day during peak hourly flow.
? The residual disinfectant concentration(s) (``C'') of the
water before or at the first customer must be measured each day during
peak hourly flow.
Systems may have several disinfection segments (the segment is
defined as a treatment unit process with a measurable disinfectant
residual level and a liquid volume) in sequence along the treatment
train. In determining the total log inactivation, the system may
calculate the log inactivation for each disinfection segment and use
the sum of the log inactivation estimates of Cryptosporidium achieved
through the

[[Page 47710]]

plant. The Toolbox Guidance Manual, available in draft with today's
proposal, provides guidance on methodologies for determining CT values
and estimating log inactivation for different disinfection reactor
designs and operations.

Table IV-19.--CT Values for Cryptosporidium Inactivation by Ozone
--------------------------------------------------------------------------------------------------------------------------------------------------------
Water Temperature, [deg]C \1\
Log credit -----------------------------------------------------------------------------------------
<=0.5 1 2 3 5 7 10 15 20 25
--------------------------------------------------------------------------------------------------------------------------------------------------------
0.5........................................................... 12 12 10 9.5 7.9 6.5 4.9 3.1 2.0 1.2
1.0........................................................... 24 23 21 19 16 13 9.9 6.2 3.9 2.5
1.5........................................................... 36 35 31 29 24 20 15 9.3 5.9 3.7
2.0........................................................... 48 46 42 38 32 26 20 12 7.8 4.9
2.5........................................................... 60 58 52 48 40 33 25 16 9.8 6.2
3.0........................................................... 72 69 63 57 47 39 30 19 12 7.4
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ CT values between the indicated temperatures may be determined by interpolation.

Table IV-20.--CT Values for Cryptosporidium Inactivation by Chlorine Dioxide
--------------------------------------------------------------------------------------------------------------------------------------------------------
Water Temperature, [deg]C \1\
Log credit -----------------------------------------------------------------------------------------
<=0.5 1 2 3 5 7 10 15 20 25
--------------------------------------------------------------------------------------------------------------------------------------------------------
0.5........................................................... 319 305 279 256 214 180 138 89 58 38
1.0........................................................... 637 610 558 511 429 360 277 179 116 75
1.5........................................................... 956 915 838 767 643 539 415 268 174 113
2.0........................................................... 1275 1220 1117 1023 858 719 553 357 232 150
2.5........................................................... 1594 1525 1396 1278 1072 899 691 447 289 188
3.0........................................................... 1912 1830 1675 1534 1286 1079 830 536 347 226
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ CT values between the indicated temperatures may be determined by interpolation.

The system may demonstrate to the State, through the use of a
State-approved protocol for on-site disinfection challenge studies or
other information satisfactory to the State, that CT values other than
those specified in Tables IV-19 or IV-20 are adequate to demonstrate
that the system is achieving the required log inactivation of
Cryptosporidium. Protocols for making such demonstrations are available
in the Toolbox Guidance Manual.
b. How was this proposal developed? EPA relied in part on analyses
by Clark et al. (2002a and 2002b) to develop the CT values for ozone
and chlorine dioxide inactivation of Cryptosporidium in today's
proposal. Clark et al. (2002a) used data from studies of ozone
inactivation of Cryptosporidium in laboratory water to develop
predictive equations for estimating inactivation (Rennecker et al.
1999, Li et al. 2001) and data from studies in natural water to
validate the equations (Owens et al. 2000, Oppenheimer et al. 2000).
For chlorine dioxide, Clark et al. (2002b) employed data from Li et al.
(2001) to develop equations for predicting inactivation, and used data
from Owens et al. (1999) and Ruffell et al. (2000) to validate the
equations.
Another step in developing the CT values for Cryptosporidium
inactivation in today's proposal involved consideration of the
appropriate confidence bound to apply when analyzing the inactivation
data. A confidence bound represents a safety margin that accounts for
variability and uncertainty in the data that underlie the analysis.
Confidence bounds are intended to provide a high likelihood that
systems operating at a given CT value will achieve at least the
corresponding log inactivation level in the CT table.
Two types of confidence bounds that are used when assessing
relationships between variables, such as disinfectant dose (CT) and log
inactivation, are confidence in the regression and confidence in the
prediction. Confidence in the regression accounts for uncertainty in
the regression line (e.g., a linear relationship between temperature
and the log of the ratio of CT to log inactivation). Confidence in the
prediction accounts for both uncertainty in the regression line and
variability in experimental observations--it describes the likelihood
of a single future data point falling within a range. Bounds for
confidence in prediction are wider (i.e., more conservative) than those
for confidence in the regression. Depending on the degree of confidence
applied, most points in a data set typically will fall within the
bounds for confidence in the prediction, while a significant fraction
will fall outside the bounds for confidence in the regression.
In developing earlier CT tables, EPA has used bounds for confidence
in the prediction. This was a conservative approach that was taken with
consideration of the limited inactivation data that were available and
that reasonably ensured systems would achieve the required inactivation
level. The November 2001 draft of the LT2ESWTR included CT tables for
Cryptosporidium inactivation by ozone and chlorine dioxide that were
derived using confidence in prediction (USEPA 2001g). However, based on
comments received on those draft tables, along with further analyses
described next, EPA has revised this approach in today's proposal.
The underlying Cryptosporidium inactivation data used to develop
the CT tables exhibit significant variability. This variability is due
to both experimental error and potential true variability in the
inactivation rate. Experimental error is associated with the assays
used to measure loss of infectivity, measurement of the disinfectant
concentration, differences in technique among researchers, and other
factors. True variability in the inactivation rate would be associated
with variability in resistance to the disinfectant between different
populations of oocysts and variability in the effect of water matrix on
the inactivation process.

[[Page 47711]]

In considering the appropriate confidence bounds to use for
developing the CT tables in today's proposal, EPA was primarily
concerned with accounting for uncertainty in the regression and for
true variability in the inactivation rate. Variability associated with
experimental error was a lessor concern, as the purpose of the CT
tables is to ensure a given level of inactivation and not predict the
measured result of an individual experiment.
Because confidence in the prediction accounts for all variability
in the data sets (both true variability and experimental error), it may
provide a higher margin of safety than is necessary. Nevertheless, in
other disinfection applications, the use of confidence in the
prediction may be appropriate, given limited data sets and uncertainty
in the source of the variability. However, the high doses of ozone and
chlorine dioxide that are needed to inactivate Cryptosporidium create
an offsetting concern with the formation of DBPs (e.g., bromate and
chlorite). In consideration of these factors and the statutory
provision for balancing risks among contaminants, EPA attempted to
exclude experimental error from the confidence bound when developing
the CT tables in today's proposal (i.e., used a less conservative
approach than confidence in the prediction).
In order to select confidence bounds reflecting potential true
variability between different oocyst populations (lots) but not
variability due to measurement and experimental imprecision, it was
necessary to estimate the relative contributions of these variance
components. This was done by first separating inactivation data points
into groups having the same Cryptosporidium oocyst lot and experimental
conditions (e.g., water matrix, pH, temperature). Next, the variance
within each group was determined. It was assumed that this within-group
variance could be attributed entirely to experimental error, as neither
of the factors expected to account for true variability in the
inactivation rate (i.e., oocyst lot or water matrix) changed within a
group. Finally, comparing the average within-group variance to the
total variance in a data set provided an indication of the fraction of
total variance that was due to experimental error (see Sivaganesan 2003
and Messner 2003 for details).
In carrying out this analysis on the Li et al. (2001) and Rennecker
et al. (1999) data sets for ozone inactivation of Cryptosporidium, EPA
estimated that 87.5% of the total variance could be attributed to
experimental error (Sivaganesan 2003). A similar analysis done by Najm
et al. (2002) on the Oppenheimer et al. (2000) data set for ozone
produced an estimate of 89% of the total variance due to experimental
error. For chlorine dioxide inactivation of Cryptosporidium, EPA
estimated that 62% of the total variance in the Li et al. (2001) and
Ruffle et al. (1999) data sets could be attributed to experimental
error (Messner 2003). The different fractions attributed to
experimental error between the chlorine dioxide and ozone data sets
presumably relates to the use of different experimental techniques
(e.g., infectivity assays).
EPA employed estimates of the fraction of variance not attributable
to experimental error (12.5% for ozone and 38% for chlorine dioxide) in
a modified form of the equation used to calculate a bound for
confidence in prediction (Messner 2003). These were applied to the
regression equations developed by Clark et al. (2002a and 2002b) in
order to estimate CT values for an upper 90% confidence bound
(Sivaganesan 2003, Messner 2003). These are the CT values shown in
Tables IV-19 and IV-20 for ozone and chlorine dioxide, respectively.
Since the available data are not sufficient to support the CT
calculation for an inactivation level greater than 3 log, the use of
Tables IV-19 and IV-20 is limited to inactivation less than or equal to
3 log. In addition, the temperature limitation for these tables is 1 to
25 [deg]C. If the water temperature is higher than 25 [deg]C,
temperature should be set to 25 [deg]C for the log inactivation
calculation.
EPA recognizes that inactivation rates may be sensitive to water
quality and operational conditions in the plant. To reflect this
potential, systems are given the option to perform a site specific
inactivation study to determine CT requirements. The State must approve
the protocols or other information used to derive alternative CT
values. However, EPA has provided guidance for systems in making such
demonstrations in the Toolbox Guidance Manual.
During meetings of the Stage 2 M-DBP Advisory Committee, CT values
were used in the model for impact analysis of different regulatory
options (the model Surface Water Analytical Tool (SWAT), as described
in Economic Analysis for the LT2ESWTR, USEPA 2003a). Those preliminary
CT values were based on a subset of the data from the Li et al. (2001)
study with laboratory waters and were adjusted with a factor to match
the mean CT values derived from the Oppenheimer et al. (2000) study
with natural waters. In comparison, the CT values in today's proposal
are higher. However, the current CT values are based on larger data
sets and more comprehensive analyses. Consequently, they provide more
confidence in estimates of Cryptosporidium log inactivation than the
preliminary estimates used in earlier SWAT modeling. EPA has
subsequently re-run analyses for LT2ESWTR impact assessments with the
updated CT values (USEPA 2003a).
c. Request for comments. EPA requests comment on the proposed
approach to awarding credit for inactivation of Cryptosporidium by
chlorine dioxide and ozone, including the following specific issues:
? Determination of CT and the confidence bounds used for
estimating log inactivation of Cryptosporidium;
? The ability of systems to apply these CT tables in
consideration of the MCLs for bromate and chlorite; and
? Any additional data that may be used to confirm or refine
the proposed CT tables.
15. Ultraviolet Light
a. What is EPA proposing today? EPA is proposing criteria for
awarding credit to ultraviolet (UV) disinfection processes for
inactivation of Cryptosporidium, Giardia lamblia, and viruses. The
inactivation credit a system can receive for each target pathogen is
based on the UV dose applied by the system in relation to the UV dose
requirements in this section (see Table IV-21).
To receive UV disinfection credit, a system must demonstrate a UV
dose using the results of a UV reactor validation test and ongoing
monitoring. The reactor validation test establishes the operating
conditions under which a reactor can deliver a required UV dose.
Monitoring is used to demonstrate that the system maintains these
validated operating conditions during routine use.
UV dose (fluence) is defined as the product of the UV intensity
over a surface area (fluence rate) and the exposure time. In practice,
UV reactors deliver a distribution of doses due to variation in light
intensity and flow path as particles pass through the reactor. However,
for the purpose of determining compliance with the dose requirements in
Table IV-21, UV dose must be assigned to a reactor based on the degree
of inactivation of a microorganism achieved during a reactor validation
test. This assigned UV dose is determined through comparing the reactor
validation test results with a known dose-response relationship for the
test microorganism. The State may

[[Page 47712]]

designate an alternative basis for awarding UV disinfection credit.
EPA is developing the UV Disinfection Guidance Manual (USEPA 2003d)
to assist systems and States with implementing UV disinfection,
including validation testing of UV reactors. This guidance is available
in draft in the docket for today's proposal (http://www.epa.gov/edocket/).
UV Dose Tables
Table IV-21 shows the UV doses that systems must apply to receive
credit for up to 3 log inactivation of Cryptosporidium and Giardia
lamblia and up to 4 log inactivation of viruses. These dose values are
for UV light at a wavelength of 254 nm as delivered by a low pressure
mercury vapor lamp. However, the dose values can be applied to other UV
lamp types (e.g., medium pressure mercury vapor lamps) through reactor
validation testing, such as is described in the draft UV Disinfection
Guidance Manual (USEPA 2003d). In addition, the dose values in Table
IV-21 are intended for post-filter application of UV in filtration
plants and for systems that meet the filtration avoidance criteria in
40 CFR 141.71.
BILLING CODE 6560-50-P
[GRAPHIC]
[TIFF OMITTED]
TP11AU03.011

BILLING CODE 6560-50-C
Reactor Validation Testing
For a system to receive UV disinfection credit, the UV reactor type
used by the system must undergo validation testing to demonstrate the
operating conditions under which the reactor can deliver the required
UV dose. Unless the State approves an alternative approach, this
testing must involve the following: (1) Full scale testing of a reactor
that conforms uniformly to the UV reactors used by the system and (2)
inactivation of a test microorganism whose dose response
characteristics have been quantified with a low pressure mercury vapor
lamp.
Validation testing must determine a set of operating conditions
that can be monitored by the system to ensure that the required UV dose
is delivered under the range of operating conditions applicable to the
system. At a minimum, these operating conditions must include flow
rate, UV intensity as measured by a UV sensor, and UV lamp status. The
validated operating conditions determined by testing must account for
the following factors: (1) UV absorbance of the water, (2) lamp fouling
and aging, (3) measurement uncertainty of on-line sensors, (4) dose
distributions arising from the velocity profiles through the reactor,
(5) failure of UV lamps or other critical system components, and (6)
inlet and outlet piping or channel configurations of the UV reactor. In
the draft UV Disinfection Guidance Manual (USEPA 2003d), EPA describes
testing protocols for reactor validation that are intended to meet
these criteria.
Reactor Monitoring
Systems must monitor for parameters necessary to demonstrate
compliance with the operating conditions that were validated for the
required UV dose. At a minimum systems must monitor for UV intensity as
measured by a UV sensor, flow rate, and lamp outage. As part of this,
systems must check the calibration of UV sensors and recalibrate in
accordance with a protocol approved by the State.
b. How was this proposal developed? UV disinfection is a physical
process relying on the transference of electromagnetic energy from a
source (lamp) to an organism's cellular material (USEPA 1986). In the
Stage 2 M-DBP Agreement in Principle, the Advisory Committee
recommended that EPA determine the UV doses needed to achieve up to 3
log inactivation of Giardia lamblia and Cryptosporidium and up to 4 log
inactivation of viruses.
The Agreement further recommends that EPA develop standards to
determine if UV systems are acceptable for compliance with drinking
water disinfection requirements, including (1) a validation protocol
for drinking water applications of UV technology and (2) on-site
monitoring requirements to ensure ongoing compliance with UV dose
tables. EPA also agreed to develop a UV guidance manual to facilitate
design and operation of UV installations. Today's proposal and

[[Page 47713]]

accompanying guidance for UV are consistent with the Agreement.
UV Dose Tables
The UV dose values in Table IV-21 are based on meta-analyses of UV
inactivation studies with Cryptosporidium parvum, Giardia lamblia,
Giardia muris, and adenovirus (Qian et al. 2003, USEPA 2003d). Proposed
UV doses for inactivation of viruses are based on the dose-response of
adenovirus because, among viruses that have been studied, it appears to
be the most UV resistant and is a widespread waterborne pathogen
(health effects of adenovirus are described in Embrey 1999).
The data supporting the dose values in Table IV-21 are from bench-
scale studies using low pressure mercury vapor lamps. These data were
chosen because the experimental conditions allow UV dose to be
accurately quantified. Low pressure lamps emit light primarily at a
single wavelength (254 nm) within the germicidal range of 200-300 nm.
However, as noted earlier, these dose tables can be applied to reactors
with other lamp types through reactor challenge testing, as described
in the draft guidance manual. Bench scale studies are preferable for
determining pathogen dose-response characteristics, due to the uniform
dose distribution.
The data sets and statistical evaluation that were used to develop
the UV dose table for Cryptosporidium, Giardia lamblia, and viruses are
described in the draft UV Disinfection Guidance Manual (USEPA 2003d)
and Qian et al. 2003.
Reactor Validation Testing
Today's proposal requires testing of full-scale UV reactors because
of the difficulty in predicting reactor disinfection performance based
on modeled results or on the results of testing at a reduced scale. All
flow-through UV reactors deliver a distribution of doses due to
variation in light intensity within the reactor and the different flow
paths of particles passing through the reactor. Moreover, the reactor
dose distribution varies temporally due to processes like lamp aging
and fouling, changes in UV absorbance of the water, and fluctuations in
flow rate. Consequently, it is more reliable to evaluate reactor
performance through a full scale test under conditions that can be
characterized as ``worst case'' for a given application. Such
conditions include maximum and minimum flow rate and reduced light
intensity within the reactor that accounts for lamp aging, fouling, and
UV absorbance of the water. Protocols for reactor validation testing
are presented in the draft UV guidance manual.
c. Request for comment. The Agency requests comment on whether the
criteria described in this section for awarding treatment credit for UV
disinfection are appropriate, and whether additional criteria, or more
specific criteria, should be included.
16. Individual Filter Performance
a. What is EPA proposing today? EPA is proposing an additional 1.0
log Cryptosporidium treatment credit for systems that achieve
individual filter performance consistent with the goals established for
the Partnership for Safe Water Phase IV in August 2001 (AWWA et al.
2001). Specifically, systems must demonstrate ongoing compliance with
the following turbidity criteria, based on continuous monitoring of
turbidity for each individual filter as required under 40 CFR 141.174
or 141.560, as applicable:

(1) Filtered water turbidity less than 0.1 NTU in at least 95%
of the maximum daily values recorded at each filter in each month,
excluding the 15 minute period following backwashes, and
(2) No individual filter with a measured turbidity level of
greater than 0.3 NTU in two consecutive measurements taken 15
minutes apart.

Note that today's proposal does not include a required peer review
step as a condition for receiving additional credit. Rather, EPA is
proposing to award additional credit to systems that meet the
performance goals of a peer review program (Phase IV). Systems that
receive the 1 log additional treatment credit for individual filter
performance, as described in this section, cannot also receive an
additional 0.5 log additional credit for lower finished water turbidity
as described in section IV.C.8.
b. How was this proposal developed? In the Stage 2 M-DBP Agreement
in Principle, the Advisory Committee recommended a peer review program
as a microbial toolbox component that should receive a 1.0 log
Cryptosporidium treatment credit. The Committee specified Phase IV of
the Partnership for Safe Water (Partnership) as an example of the type
of peer review program where a 1.0 log credit would be appropriate.
The Partnership is a voluntary cooperative program involving EPA,
the Association of Metropolitan Water Agencies (AMWA), the American
Water Works Association (AWWA), the National Association of Water
Companies (NAWC), the Association of State Drinking Water
Administrators (ASDWA), the American Water Works Association Research
Foundation (AWWARF), and surface water utilities throughout the United
States. The intent of the Partnership is to increase protection against
microbial contaminants by optimizing treatment plant performance.
At the time of the Advisory Committee recommendation, Phase IV was
under development by the Partnership. It was to be based on Composite
Correction Program (CCP) (USEPA 1991) procedures and performance goals,
and was to be awarded based on an on-site evaluation by a third-party
team. The performance goals for Phase IV were such that, over a year,
each sedimentation basin and each filter would need to produce
specified turbidity levels based on the maximum of all the values
recorded during the day. Sedimentation performance goals were set at
2.0 NTU if the raw water was greater than 10 NTU on an annual basis and
1.0 NTU if the raw water was less than 10 NTU. Each filter was to meet
0.1 NTU 95% of the time except for the 15 minute period following
placing the filter in operation. In addition, filters were expected to
have maximum turbidity of 0.3 NTU and return to less than 0.1 NTU
within 15 minutes of the filter being placed in service.
The primary purpose of the on-site evaluation was to confirm that
the performance of the plant was consistent with Phase IV performance
goals and that the system had the administrative support and
operational capabilities to sustain the performance long-term. The on-
site evaluation in Phase IV also allowed utilities that could not meet
the desired performance goals to demonstrate to the third-party that
they had achieved the highest level of performance given their unique
raw water quality.
After the signing of the Stage 2 M-DBP Agreement in Principle in
September 2000, the Partnership decided to eliminate the on-site third-
party evaluation as a component of Phase IV. Instead, the requirement
for Phase IV is for the water system to complete an application package
that will be reviewed by trained utility volunteers. Included in the
application package is an Optimization Assessment Spreadsheet in which
the system enters water quality and treatment data to demonstrate that
Phase IV performance levels have been achieved. The application also
requires narratives related to administrative support and operational
capabilities to sustain performance long-term.
Today's proposal is consistent with the performance goals of Phase
IV.

[[Page 47714]]

Rather than require systems to complete an application package with
historical data and narratives, the LT2ESWTR requires systems to
demonstrate to the State that they meet the individual filter
performance goals of Phase IV on an ongoing basis to receive the 1.0
log additional Cryptosporidium treatment credit. EPA is not requiring
systems to demonstrate that they meet sedimentation performance goals
of Phase IV. While EPA recognizes that settled water turbidity is an
important operational performance measure for a plant, the Agency does
not have data directly relating it to finished water quality and
pathogen risk.
The November 2001 pre-proposal draft of the LT2ESWTR described a
potential 1.0 log credit for systems that achieved individual filter
effluent (IFE) turbidity below 0.15 NTU in 95 percent of samples (USEPA
2001g). The Science Advisory Board (SAB) subsequently reviewed this
credit and supporting data on the relationship between filter effluent
turbidity and Cryptosporidium removal efficiency (described in section
IV.C.8). In written comments from a December 2001 meeting of the
Drinking Water Committee, an SAB panel recommended only a 0.5 log
credit for 95th percentile IFE turbidity below 0.15 NTU.
To address this recommendation from the SAB, EPA is proposing that
systems meet the individual filter performance criteria of Phase IV of
the Partnership in order to be eligible for a 1.0 log additional
Cryptosporidium treatment credit. This proposed approach responds to
the concerns raised by the SAB because the Phase IV criteria are more
stringent than those in the 2001 pre-proposal draft of the LT2ESWTR.
For example, today's proposal sets a maximum limit on individual filter
effluent turbidity of 0.3 NTU, whereas no such upper limit was
described in the 2001 pre-proposal draft.
In summary, EPA has concluded that it is appropriate to award
additional Cryptosporidium treatment credit for systems meeting
stringent individual filter performance standards. Modestly elevated
turbidity from a single filter may not significantly impact combined
filter effluent turbidity levels, which are regulated under IESWTR and
LT1ESWTR, but may indicate a substantial reduction in the overall
pathogen removal efficiency of the filtration process. Consequently,
systems that continually achieve very low turbidity in each individual
filter are likely to provide a significantly more effective microbial
barrier. EPA expects that systems that select this toolbox option will
have achieved a high level of treatment process optimization and
process control, and will have both a history of consistent performance
over a range of raw water quality conditions and the capability and
resources to maintain this performance long-term.
c. Request for comment. The Agency invites comment on the following
issues related to the proposed credit for individual filter
performance.
? Are there different or additional performance measures that
a utility should be required to meet for the 1 log additional credit?
? Are there existing peer review programs for which treatment
credit should be awarded under the LT2ESWTR? If so, what role should
primacy agencies play in establishing and managing any such peer review
program?
? The individual filter effluent turbidity criterion of 0.1
NTU is proposed because it is consistent with Phase IV Partnership
standards, as based on CCP goals. However, with allowable rounding,
turbidity levels less than 0.15 NTU are in compliance with a standard
of 0.1. Consequently, EPA requests comment on whether 0.15 NTU should
be the standard for individual filter performance credit, as this would
be consistent with the standard of 0.15 NTU that is proposed for
combined filter performance credit in section IV.C.8.
17. Other Demonstration of Performance
a. What is EPA proposing today? The purpose of the ``demonstration
of performance'' toolbox component is to allow a system to demonstrate
that a plant, or a unit process within a plant, should receive a higher
Cryptosporidium treatment credit than is presumptively awarded under
the LT2ESWTR. For example, as described in section IV.A, plants using
conventional treatment receive a presumptive 3 log credit towards the
Cryptosporidium treatment requirements in Bins 2-4 of the LT2ESWTR.
This credit is based on a determination by EPA that conventional
treatment plants achieve an average Cryptosporidium removal of 3 log
when in compliance with the IESWTR or LT1ESWTR. However, EPA recognizes
that some conventional treatment plants may achieve average
Cryptosporidium removal efficiencies greater than 3 log. Similarly,
some systems may achieve Cryptosporidium reductions with certain
toolbox components that are greater than the presumptive credits
awarded under the LT2ESWTR, as described in this section (IV.C).
Where a system can demonstrate that a plant, or a unit process
within a plant, achieves a Cryptosporidium reduction efficiency greater
than the presumptive credit specified in the LT2ESWTR, it may be
appropriate for the system to receive a higher Cryptosporidium
treatment credit. Today's proposal does not include specific protocols
for systems to make such a demonstration, due to the potentially
complex and site specific nature of the testing that would be required.
Rather, today's proposal allows a State to award a higher level of
Cryptosporidium treatment credit to a system where the State
determines, based on site-specific testing with a State-approved
protocol, that a treatment plant or a unit process within a plant
reliably achieves a higher level of Cryptosporidium removal on a
continuing basis. Also, States may award a lower level of
Cryptosporidium treatment credit to a system where a State determines,
based on site specific information, that a plant or a unit process
within a plant achieves a Cryptosporidium removal efficiency less than
a presumptive credit specified in the LT2ESWTR.
Systems receiving additional Cryptosporidium treatment credit
through a demonstration of performance may be required by the State to
report operational data on a monthly basis to establish that conditions
under which demonstration of performance credit was awarded are
maintained during routine operation. The Toolbox Guidance Manual (USEPA
2003f) will describe potential approaches to demonstration of
performance testing. This guidance is available in draft in the docket
for today's proposal (http://www.epa.gov/edocket/).
Note that as described in section IV.C, today's proposal allows
treatment plants to achieve additional Cryptosporidium treatment credit
through meeting the design and/or operational criteria of microbial
toolbox components, such as combined and individual filter performance,
presedimentation, bank filtration, two-stage softening, secondary
filtration, etc. Plants that receive additional Cryptosporidium
treatment credit through a demonstration of performance are not also
eligible for the presumptive credit associated with microbial toolbox
components if the additional removal due to the toolbox component is
captured in the demonstration of performance credit. For example, if a
plant receives a demonstration of performance credit based on removal
of Cryptosporidium or an indicator while operating under conditions of
lower finished water turbidity, the plant may not also receive
additional presumptive credit for lower

[[Page 47715]]

finished water turbidity toolbox components.
This demonstration of performance credit does not apply to the use
of chlorine dioxide, ozone, or UV light, because today's proposal
includes specific provisions allowing the State to modify the standards
for awarding disinfection credit to these technologies. As described in
section IV.C.14, States can approve site-specific CT values for
inactivation of Cryptosporidium by chlorine dioxide and ozone; as
described in section IV.C.15, States can approve an alternative
approach for validating the performance of UV reactors.
b. How was this proposal developed? The Stage 2 M-DBP Agreement in
Principle recommends demonstration of performance as a process for
systems to receive Cryptosporidium treatment credit higher than the
presumptive credit for many microbial toolbox components, as well as
credit for technologies not listed in the toolbox. EPA is aware that
there may be plants where particular unit processes, or combinations of
unit processes, achieve greater Cryptosporidium removal than the
presumptive credit awarded under the LT2ESWTR. In addition, the Agency
would like to allow for the use of Cryptosporidium treatment processes
not addressed in the LT2ESWTR, where such processes can demonstrate a
reliable specific log removal. Due to these factors, EPA is proposing a
demonstration of performance component in the microbial toolbox,
consistent with the Advisory Committee recommendation.
The Agreement in Principle makes no recommendations for how a
demonstration of performance should be conducted. It is generally not
practical for systems to directly quantify high log removal of
Cryptosporidium in treatment plants because of the relatively low
occurrence of Cryptosporidium in many raw water sources and limitations
with analytical methods. Consequently, if systems are to demonstrate
the performance of full scale plants in removing Cryptosporidium, this
typically will require the use of indicators, where the removal of the
indicator has been correlated with the removal of Cryptosporidium. As
described previously, a number of studies have shown that aerobic
spores are an indicator of Cryptosporidium removal by sedimentation and
filtration (Dugan et al. 2001, Emelko et al. 1999 and 2000, Yates et
al. 1998, Mazounie et al. 2000).
The nature of demonstration of performance testing that will be
appropriate at a given facility will depend on site specific factors,
such as water quality, the particular process(es) being evaluated,
resources and infrastructure, and the discretion of the State.
Consequently, EPA is not proposing specific criteria for demonstration
of performance testing. Instead, systems must develop a testing
protocol that is approved by the State, including any requirements for
ongoing reporting if demonstration of performance credit is approved.
EPA has developed a draft document, Toolbox Guidance Manual (USEPA
2003f), that is available with today's proposal and provides guidance
on demonstration of performance testing.
c. Request for comment. The Agency requests comment on today's
proposal for systems to demonstrate higher Cryptosporidium removal
levels. EPA specifically requests comment on the following issues:
? Approaches that should be considered or excluded for
demonstration of performance testing;
? Whether EPA should propose minimum elements that
demonstration of performance testing must include;
? Whether a factor of safety should be applied to the results
of demonstration of performance testing to account for potential
differences in removal of an indicator and removal of Cryptosporidium,
or uncertainty in the application of pilot-scale results to full-scale
plants;
? Whether or under what conditions a demonstration of
performance credit should be allowed for a unit process within a
plant--a potential concern is that certain unit processes, such as a
sedimentation basin, can be operated in a manner that will increase
removal in the unit process but decrease removal in subsequent
treatment processes and, therefore, lead to no overall increase in
removal through the plant. An approach to address this concern is to
limit demonstration of performance credit to removal demonstrated
across the entire treatment plant.

D. Disinfection Benchmarks for Giardia lamblia and Viruses

1. What Is EPA Proposing Today?
EPA proposes to establish the disinfection benchmark under the
LT2ESWTR as a procedure to ensure that systems maintain protection
against microbial pathogens as they implement the Stage 2 M-DBP rules
(i.e., Stage 2 DBPR and LT2ESWTR). The disinfection benchmark serves as
a tool for systems and States to evaluate the impact on microbial risk
of proposed changes in disinfection practice. EPA established the
disinfection benchmark under the IESWTR and LT1ESWTR for the Stage 1 M-
DBP rules, as recommended by the Stage 1 M-DBP Advisory Committee.
Today's proposal extends disinfection benchmark requirements to apply
to the Stage 2 M-DBP rules.
Under the proposed LT2ESWTR, the disinfection benchmark procedure
involves a system charting levels of Giardia lamblia and virus
inactivation at least once per week over a period of at least one year.
This creates a profile of inactivation performance that the System must
use to determine a baseline or benchmark of inactivation against which
proposed changes in disinfection practice can be measured. Only certain
systems are required to develop profiles and keep them on file for
State review during sanitary surveys. When those systems that are
required to develop a profile plan a significant change in disinfection
practice (defined later in this section), they must submit the profile
and an analysis of how the proposed change will affect the current
disinfection benchmark to the State for review.
Systems that developed disinfection profiles under the IESWTR or
LT1ESWTR and have not made significant changes in their disinfection
practice or changed sources are not required to collect additional
operational data to create disinfection profiles under the LT2ESWTR.
Systems that produced a disinfection profile for Giardia lamblia but
not viruses under the IESWTR or LT1ESWTR may be required to develop a
profile for viruses under the LT2ESWTR. Where a previously developed
Giardia lamblia profile is acceptable, systems may develop a virus
profile using the same operational data (i.e., CT values) on which the
Giardia lamblia profile is based. Spreadsheets developed by EPA and
States automatically calculate Giardia lamblia and virus profiles using
the same operational data. EPA believes that virus profiling is
necessary because many of the disinfection processes that systems will
select to comply with the Stage 2 DBPR and LT2ESWTR (e.g., chloramines,
UV, MF/UF) are relatively less effective against viruses than Giardia
lamblia in comparison to free chlorine.
The disinfection benchmark provisions contain three major
components: (a) Applicability requirements and schedule, (b)
characterization of disinfection practice, and (c) State review of
proposed changes in disinfection practice. Each of these components is
discussed in the following paragraphs.

[[Page 47716]]

a. Applicability and schedule. Proposed disinfection profiling and
benchmarking requirements apply to surface water systems only. Systems
serving only ground water are not subject to the requirements of the
LT2ESWTR. The determination of whether a surface water system is
required to develop a disinfection profile is based on whether DBP
levels (TTHM or HAA5) exceed specified values, described later in this
section, and whether a system is required to monitor for
Cryptosporidium. These criteria trigger profiling because they identify
systems that may be required to make treatment changes under the Stage
2 DBPR or LT2ESWTR. Note that it is not practical to wait until a
system has completed Cryptosporidium monitoring to identify which
systems should prepare a disinfection profile. A completed disinfection
profile should be available at the point when a system is classified in
a treatment bin and must begin developing plans to comply with any
additional treatment requirements.
Unless the system developed a disinfection profile under the IESWTR
or LT1ESWTR, all systems required to monitor for Cryptosporidium must
develop Giardia lamblia and virus disinfection profiles under the
LT2ESWTR. This includes all surface water systems except (1) systems
that provide 5.5 log total treatment for Cryptosporidium, equivalent to
meeting the treatment requirements of Bin 4 and (2) small systems
(<10,000 people served) that do not exceed the E. coli trigger (see
section IV.A for details). Systems not required to monitor for
Cryptosporidium as a result of providing 5.5 log of treatment are not
required to prepare disinfection profiles. However, small systems that
do not exceed the E. coli trigger are required to prepare Giardia
lamblia and virus disinfection profiles if one of the following
criteria apply, based on DBP levels in their distribution systems:
(1)* TTHM levels in the distribution system, based on samples
collected for compliance with the Stage 1 DBPR, are at least 80% of the
MCL (0.064 mg/L) at any Stage 1 DBPR sampling point based on a
locational running annual average (LRAA).
(2)* HAA5 levels in the distribution system, based on the samples
collected for compliance with the Stage 1 DBPR, are at least 80% of the
MCL (0.048 mg/L) at any Stage 1 DBPR sampling point based on an LRAA.

*These criteria only apply to systems that are required to comply with
the DBP rules, i.e., community and non-transient non-community systems.
Table IV-22 presents a summary schedule of the required deadlines
for disinfection profiling activities, categorized by system size and
whether a small system is required to monitor for Cryptosporidium. The
deadlines are based on the expectation that a system should have a
disinfection profile at the time the system is classified in a
Cryptosporidium treatment bin under LT2ESWTR and/or has determined the
need to make treatment changes for the Stage 2 DBPR. Systems have three
years from this date, with a possible two year extension for capital
improvements if granted by the State, within which to complete their
evaluation, design, and implementation of treatment changes to meet the
requirements of the LT2ESWTR and the Stage 2 DBPR.

Table IV-22.--Schedule of Implementation Deadlines Related to Disinfection Profiling \1\
----------------------------------------------------------------------------------------------------------------
Systems serving <10,000 people
---------------------------------
Systems serving Not required to
Activity £=10,000 Required to monitor for
people \2\ monitor for Cryptosporidium
Cryptosporidium 2 3 6
----------------------------------------------------------------------------------------------------------------
Complete 1 year of E. coli monitoring..................... NA 42 42
Determine whether required to profile based on DBP levels NA NA 42
and notify State \6\.....................................
Begin disinfection profiling\4\........................... 24 54 42
Complete Cryptosporidium monitoring....................... 30 60 NA
Complete disinfection profiling based on at least one 36 66 54
year's data \5\..........................................
----------------------------------------------------------------------------------------------------------------
\1\ Numbers in table indicate months following promulgation of the LT2ESWTR.
\2\ Systems providing a total of 5.5 log Cryptosporidium treatment (equivalent to meeting Bin 4 treatment
requirements) are not required to develop disinfection profiles.
\3\ Systems serving fewer than 10,000 people are not required to monitor for Cryptosporidium if mean E. coli
levels are less than 10/100 mL for systems using lake/reservoir sources or less than 50/100 mL for systems
using flowing stream sources.
\4\ Unless system has existing disinfection profiling data that are acceptable.
\5\ This deadline coincides with the start of the 3 year period at the end of which compliance with the LT2ESWTR
and Stage 2 DBPR is required.
\6\ Not required to conduct profiling unless TTHM or HAA5 exceeds trigger values of 80% of MCL at any sampling
point based on LRAA.

As described in the next section, systems can meet profiling
requirements under the proposed LT2ESWTR using previously collected
data (i.e., grandfathered data). Use of grandfathered data is allowed
if the system has not made a significant change in disinfection
practice or changed sources since the data were collected. This will
permit most systems that prepared a disinfection profile under the
IESWTR or the LT1ESWTR to avoid collecting any new operational data to
develop profiles under the LT2ESWTR.
The locational running annual average (LRAA) of TTHM and HAA5
levels used by small systems that do not monitor for Cryptosporidium to
determine whether profiling is required must be based on one year of
DBP data collected during the period following promulgation of the
LT2ESWTR, or as determined by the State. By the date indicated in Table
IV-22, these systems must report to the State on their DBP LRAAs and
whether the disinfection profiling requirements apply. If either DBP
LRAA meets the criteria specified previously, the system must begin
disinfection profiling by the date proposed in Table IV-22.
b. Developing the disinfection profile and benchmark. Under the
LT2ESWTR, a disinfection profile consists of a compilation of Giardia
lamblia and virus log inactivation levels computed at least weekly over
a period of at least one year, as based on operational and water
quality data (disinfectant residual concentration(s), contact time(s),
temperature(s), and, where necessary, pH). The system may create the
profile by conducting new weekly (or more frequent) monitoring and/or
by using

[[Page 47717]]

grandfathered data. A system that created a Giardia lamblia
disinfection profile under the IESWTR or LT1ESWTR may use the
operational data collected for the Giardia lamblia profile to create a
virus disinfection profile.
Grandfathered data are those operational data that a system has
previously collected at a treatment plant during the course of normal
operation. Those systems that have all the necessary information to
determine profiles using existing operational data collected prior to
the date when the system is required to begin profiling may use these
data in developing profiles. However, grandfathered data must be
substantially equivalent to operational data that would be collected
under this rule. These data must be representative of inactivation
through the entire treatment plant and not just of certain treatment
segments.
To develop disinfection profiles under this rule, systems are
required to exercise one of the following three options:
Option 1--Systems conduct monitoring at least once per week
following the process described later in this section.
Option 2--Systems that conduct monitoring under this rule, as
described under Option 1, can also use one or two years of acceptable
grandfathered data, in addition to one year of new operational data, in
developing the disinfection profile.
Option 3--Systems that have at least one year of acceptable
existing operational data are not required to conduct new monitoring to
develop the disinfection profile under this rule. Instead, they can use
a disinfection profile based on one to three years of grandfathered
data.
Process to be followed by PWS for developing the disinfection
profile:

--Measure disinfectant residual concentration (C, in mg/L) before or at
the first customer and just prior to each additional point of
disinfectant addition, whether with the same or a different
disinfectant.
--Determine contact time (T, in minutes) for each residual disinfectant
monitoring point during peak flow conditions. T could be based on
either a tracer study or assumptions based on contactor basin geometry
and baffling. However, systems must use the same method for both
grandfathered data and new data.
--Measure water temperature ([deg]C) (for disinfectants other than UV).
--Measure pH (for chlorine only).

To determine the weekly log inactivation, the system must convert
operational data from one day each week to the corresponding log
inactivation values for Giardia lamblia and viruses. The procedure for
Giardia lamblia is as follows:

--Determine CT_calc for each disinfection segment.
--Determine CT_99.9 (i.e., 3 log inactivation) from tables in
the SWTR (40 CFR 141.74) using temperature (and pH for chlorine) for
each disinfection segment. States can allow an alternate calculation
procedure (e.g., use of a spreadsheet).
--For each segment, log inactivation = (CT_calc/
CT_99.9) x 3.0.
--Sum the log inactivation values for each segment to get the log
inactivation for the day (or week).

For calculating the virus log inactivation, systems should use the
procedures approved by States under the IESWTR or LT1ESWTR. Log
inactivation benchmark is calculated as follows:

--Determine the calendar month with the lowest log inactivation.
--The lowest month becomes the critical period for that year.
--If acceptable data from multiple years are available, the average of
critical periods for each year becomes the benchmark.
--If only one year of data is available, the critical period for that
year is the benchmark.

c. State review. If a system that is required to produce a
disinfection profile proposes to make a significant change in
disinfection practice, it must calculate Giardia lamblia and virus
inactivation benchmarks and must notify the State before implementing
such a change. Significant changes in disinfection practice are defined
as (1) moving the point of disinfection (this is not intended to
include routine seasonal changes already approved by the State), (2)
changing the type of disinfectant, (3) changing the disinfection
process, or (4) making other modifications designated as significant by
the State. When notifying the State, the system must provide a
description of the proposed change, the disinfection profiles and
inactivation benchmarks for Giardia lamblia and viruses, and an
analysis of how the proposed change will affect the current
inactivation benchmarks. In addition, the system should have
disinfection profiles and, if applicable, inactivation benchmarking
documentation, available for the State to review as part of its
periodic sanitary survey.
EPA developed for the IESWTR, with stakeholder input, the
Disinfection Profiling and Benchmarking Guidance Manual (USEPA 1999d).
This manual provides guidance to systems and States on the development
of disinfection profiles, identification and evaluation of significant
changes in disinfection practices, and considerations for setting an
alternative benchmark. If necessary, EPA will produce an addendum to
reflect changes in the profiling and benchmarking requirements
necessary to comply with LT2ESWTR.
2. How Was This Proposal Developed?
A fundamental premise in the development of the M-DBP rules is the
concept of balancing risks between DBPs and microbial pathogens.
Disinfection profiling and benchmarking were established under the
IESWTR and LT1ESWTR, based on a recommendation by the Stage 1 M-DBP
Federal Advisory Committee, to ensure that systems maintained adequate
control of pathogen risk as they reduced risk from DBPs. Today's
proposal would extend disinfection benchmarking requirements to the
LT2ESWTR.
EPA believes this extension is necessary because some systems will
make significant changes in their current disinfection practice to meet
more stringent limits on TTHM and HAA5 levels under the Stage 2 DBPR
and additional Cryptosporidium treatment requirements under the
LT2ESWTR. In order to ensure that these systems continue to provide
adequate protection against the full spectrum of microbial pathogens,
it is appropriate for systems and States to evaluate the effects of
such treatment changes on microbial drinking water quality. The
disinfection benchmark serves as a tool for making such evaluations.
EPA projects that to comply with the Stage 2 DBPR, systems will
make changes to their disinfection practice, including switching from
free chlorine to chloramines and, to a lesser extent, installing
technologies like ozone, membranes, and UV. Similarly, to provide
additional treatment for Cryptosporidium, some systems will install
technologies like UV, ozone, and microfiltration. While these processes
are all effective disinfectants, chloramines are a weaker disinfectant
than free chlorine for Giardia lamblia. Ozone, UV, and membranes can
provide highly effective treatment for Giardia lamblia, but they, as
well as chloramines, are less efficient for treating viruses than free
chlorine, relative to their efficacy for Giardia lamblia. Because of
this, a system switching from free chlorine to one of these alternative
disinfection

[[Page 47718]]

technologies could experience a reduction in the level of virus and/or
Giardia lamblia (for chloramines) treatment it is achieving.
Consequently, EPA believes that systems making significant changes in
their disinfection practice under the Stage 2 M-DBP rules should assess
the impact of these changes with disinfection benchmarks for Giardia
lamblia and viruses.
Changes in the proposed benchmarking requirements under the
LT2ESWTR in comparison to IESWTR requirements include decreasing the
frequency of calculating CT values for the disinfection profile from
daily to weekly and requiring all systems to prepare a profile for
viruses as well as Giardia lamblia. The proposal of a weekly frequency
for CT calculations was made to accommodate existing profiles from
small systems, which are required to make weekly CT calculations for
profiling under the LT1ESWTR. As described earlier, EPA would like for
systems that have prepared a disinfection profile under the IESWTR or
LT1ESWTR and have not subsequently made significant changes in
disinfection practice to be able to grandfather this profile for the
LT2ESWTR. Allowing weekly calculation of CT values under the LT2ESWTR
will make this possible.
The IESWTR and LT1ESWTR required virus inactivation profiling only
for systems using ozone or chloramine as their primary disinfectant.
However, as noted earlier, EPA has projected that under the Stage 2
DBPR and LT2ESWTR, systems will switch from free chlorine to
disinfection processes like chloramines, UV, ozone, and
microfiltration. The efficiency of these processes for virus treatment
relative to protozoa treatment is lower in comparison to free chlorine.
As a result, a disinfection benchmark for Giardia lamblia would not
necessarily provide an indication of the level or adequacy of treatment
for viruses. Consequently, EPA believes it is appropriate for systems
to develop profiles for both Giardia lamblia and viruses. Moreover,
developing a profile for viruses involves a minimal increase in effort
and no additional data collection for those systems that have
disinfection profiles for Giardia lamblia. Systems will use the same
calculated CT values for viruses as would be used for the Giardia
lamblia profile.
The strategy of disinfection profiling and benchmarking stemmed
from data provided to the Stage1 M-DBP Advisory Committee, in which the
baseline of microbial inactivation (expressed as logs of Giardia
lamblia inactivation) demonstrated high variability. Inactivation
varied by several logs (i.e., orders of magnitude) on a day-to-day
basis at particular treatment plants and by as much as tens of logs
over a year due to changes in water temperature, flow rate, seasonal
changes, pH, and disinfectant demand. There were also differences
between years at individual plants. To address these variations, M-DBP
stakeholders developed the procedure of profiling a plant's
inactivation levels over a period of at least one year, and then
establishing a benchmark of minimum inactivation as a way to
characterize disinfection practice.
Benchmarking of inactivation levels, an assessment of the impact of
proposed changes on the level of microbial inactivation of Giardia
lamblia and viruses, and State review prior to approval of substantial
changes in treatment are important steps in avoiding conditions that
present an increase in microbial risk. In its assessment of the
microbial risk associated with the proposed changes, States could
consider site-specific knowledge of the watershed and hydrologic
factors as well as variability, flexibility and reliability of
treatment to ensure that treatment for both protozoan and viral
pathogens is appropriate.
EPA emphasizes that benchmarking is not intended to function as a
regulatory standard. Rather, the objective of the disinfection
benchmark is to facilitate interactions between the States and systems
for the purpose of assessing the impact on microbial risk of proposed
significant changes to current disinfection practices. Final decisions
regarding levels of disinfection for Giardia lamblia and viruses beyond
those required by the SWTR that are necessary to protect public health
will continue to be left to the States. For this reason EPA has not
mandated specific evaluation protocols or decision matrices for
analyzing changes in disinfection practice. EPA, however, will provide
support to the States in making these analyses through the issuance of
guidance.
3. Request for Comments
EPA requests comment on the proposed provisions of the inactivation
profiling and benchmarking requirement.

E. Additional Treatment Technique Requirements for Systems With
Uncovered Finished Water Storage Facilities

1. What Is EPA Proposing Today?
EPA is proposing requirements for systems with uncovered finished
water storage facilities. The proposed rule requires that systems with
uncovered finished water storage facilities must (1) cover the
uncovered finished water storage facility, or (2) treat storage
facility discharge to the distribution system to achieve a 4 log virus
inactivation, unless (3) the system implements a State-approved risk
mitigation plan that addresses physical access and site security,
surface water runoff, animal and bird waste, and ongoing water quality
assessment, and includes a schedule for plan implementation. Where
applicable, the plans should account for cultural uses by Indian
Tribes.
Systems must notify the State if they use uncovered finished water
storage facilities no later than 2 years following LT2ESWTR
promulgation. Systems must cover or treat uncovered finished facilities
or have a State-approved risk mitigation plan within 3 years following
LT2ESWTR promulgation, with the possibility of a two year extension
granted by States for systems making capital improvements. Systems
seeking approval for a risk mitigation plan must submit the plan to the
State within 2 years following LT2ESWTR promulgation.
These provisions apply to uncovered tanks, reservoirs, or other
facilities where water is stored after it has undergone treatment to
satisfy microbial treatment technique requirements for Giardia lamblia,
Cryptosporidium, and viruses. In most cases, this refers to storage of
water following all filtration steps, where required, and primary
disinfection.
2. How Was This Proposal Developed?
Today's proposal is intended to mitigate the water quality
degradation and increased health risks that can result from uncovered
finished water storage facilities. In addition, these proposed
requirements for uncovered finished water storage facilities are
consistent with recommendations of the Stage 2 M-DBP Advisory Committee
in the Agreement in Principle (USEPA 2000a).
The use of uncovered finished water storage facilities has been
questioned since 1930 due to their susceptibility to contamination and
subsequent threats to public health (LeChevallier et al. 1997). Many
potential sources of contamination can lead to the degradation of water
quality in uncovered finished water storage facilities. These include
surface water runoff, algal growth, insects and fish, bird and animal
waste, airborne deposition, and human activity.

[[Page 47719]]

Algal blooms are the most common problem in open reservoirs and can
become a public health risk, as they increase the presence of bacteria
in the water. Algae growth also leads to the formation of disinfection
byproducts and causes taste and odor problems. Some algae produce
toxins that can induce headache, fever, diarrhea, abdominal pain,
nausea, and vomiting. Bird and animal wastes are also common and
significant sources of contamination. These wastes may carry microbial
contaminants such as coliform bacteria, viruses, and human pathogens,
including Vibrio cholera, Salmonella, Mycobacteria, Typhoid, Giardia
lamblia, and Cryptosporidium (USEPA 1999e). Microbial pathogens are
found in surface water runoff, along with agricultural chemicals,
automotive wastes, turbidity, metals, and organic matter (USEPA 1999e,
LeChevallier et al. 1997).
In an effort to minimize contamination, systems have implemented
various controls such as reservoir covers and liners, regular draining
and washing, security and monitoring, bird and insect control programs,
and drainage design to prevent surface runoff from entering the
facility (USEPA 1999e).
A number of studies have evaluated the degradation of water quality
in uncovered finished water storage facilities. LeChevallier et al.
(1997) compared influent and effluent samples from six uncovered
finished water storage reservoirs in New Jersey for a one year period.
There were significant increases in the turbidity, particle count,
total coliform, fecal coliform, and heterotrophic plate count bacteria
in the effluent relative to the influent. Of particular concern were
fecal coliforms, which were detected in 18 percent of effluent samples
(no influent samples were positive for coliforms). Fecal coliforms are
used as an indicator of the potential for contamination by pathogens.
Giardia and/or Cryptosporidium were detected in 15% of inlet samples
and 25% of effluent samples, demonstrating a significant increase in
the effluent. There was a significant decrease in the chlorine residual
concentration in some effluent samples.
Increases in algal cells, heterotrophic plate count (HPC) bacteria,
turbidity, color, particle counts, and biomass, and decreases in
residual chlorine levels, have been reported in other studies of
uncovered finished water reservoirs as well (Pluntze 1974, AWWA
Committee 1983, Silverman et al. 1983). Researchers have shown that
small mammals, birds, fish, and algal growth contribute to the
microbial degradation of an open finished water reservoir (Graczyk et
al. 1996, Geldreich 1990, Fayer and Ungar 1986, Current 1986).
As described in section II, the IESWTR and LT1ESWTR require water
systems to cover all new reservoirs, holding tanks, or other storage
facilities for finished water. However, these rules do not require
systems to cover existing finished water storage facilities. EPA stated
in the preamble to the final IESWTR (63 FR 69494, December 16, 1998)
(USEPA 1998a) that with respect to requirements for existing uncovered
finished water storage facilities, the Agency needed more time to
collect and analyze additional information to evaluate regulatory
impact. The IESWTR preamble affirmed that EPA would consider whether to
require the covering of existing storage facilities during the
development of subsequent microbial regulations when additional data to
estimate national costs were available.
Since promulgation of the IESWTR, EPA has collected sufficient data
to estimate national cost implications of regulatory control strategies
for uncovered finished water storage facilities. Based on information
provided by States, EPA estimates that there are approximately 138
uncovered finished water storage facilities in the United States and
territories, not including reservoirs that systems currently plan to
cover or take off-line. Costs for covering these storage facilities or
treating the effluent, consistent with today's proposed requirements,
are presented in section VI of this preamble and in the Economic
Analysis for the LT2ESWTR (USEPA 2003a). Briefly, total capital costs
were estimated as $64.4 million, resulting in annualized present value
costs of $5.4 million at a three percent discount rate and $6.4 million
at a seven percent discount rate.
Based on the findings of studies cited in this section, EPA
continues to be concerned about contamination occurring in uncovered
finished water storage facilities. Therefore, as recommended by the
Advisory Committee, EPA is proposing control measures for all systems
with uncovered finished water storage facilities. This proposal is
intended to represent a balanced approach, recognizing both the
potentially significant but uncertain risks associated with uncovered
finished water storage facilities and the substantial costs of either
covering them or building alternative storage. Today's proposal allows
systems to treat the storage facility effluent instead of providing a
cover. Alternatively, States may determine that existing risk
mitigation is adequate, provided a system implements a risk mitigation
plan as described in this section.
3. Request for Comments
EPA requests comment on the proposed requirements pertaining to
uncovered finished water storage facilities. Specifically, the Agency
would like comment on the following issues, and requests that comments
include available supporting data or other technical information:
? Is it appropriate to allow systems with uncovered finished
water storage facilities to implement a risk management plan or treat
the effluent to inactivate viruses instead of covering the facility?
? If systems treat the effluent of an uncovered finished
water storage facility instead of covering it, should systems be
required to inactivate Cryptosporidium and Giardia lamblia, since these
protozoa have been found to increase in uncovered storage facilities?
? Additional information on contamination or health risks
that may be associated with uncovered finished water storage
facilities.
? Additional data on how climatological conditions affect
water quality, including daily fluctuations in the stability of the
water related to corrosion control.
? The definition of an uncovered finished water storage
facility in 40 CFR 141.2 is a tank, reservoir, or other facility used
to store water that will undergo no further treatment except residual
disinfection and is open to the atmosphere. There is a concern that
this definition may not include certain systems using what would
generally be considered an uncovered finished water storage facility.
An example is a system that applies a corrosion inhibitor compound to
the effluent of an uncovered storage facility where water is stored
after filtration and primary disinfection. In this case, the system may
claim that the corrosion inhibitor constitutes additional treatment
and, consequently, the reservoir does not meet EPA's definition of an
uncovered finished water storage facility. EPA requests comment on
whether the definition of an uncovered finished water storage facility
should be revised to specifically include systems that apply a
treatment such as corrosion control to water stored in an uncovered
reservoir after the water has undergone filtration, where required, and
primary disinfection.

F. Compliance Schedules

Today's proposal includes deadlines for public water systems to
comply with

[[Page 47720]]

the proposed monitoring, reporting, and treatment requirements. These
deadlines stem from the microbial framework approach of the proposed
LT2ESWTR, which involves a system-specific risk characterization
through monitoring to determine the need for additional treatment.
1. What Is EPA Proposing Today?
a. Source water monitoring.
i. Filtered systems. Under today's proposal, filtered systems
conduct source water Cryptosporidium monitoring for the purpose of
being classified in one of four risk bins that determine the extent of
any additional treatment requirements. Small filtered systems first
monitor for E. coli as a screening analysis and are only required to
monitor for Cryptosporidium if the mean E. coli level exceeds specified
trigger values. Note that systems that currently provide or will
provide a total of at least 5.5 log of treatment for Cryptosporidium
are exempt from monitoring requirements.
Large surface water systems (serving at least 10,000 people) that
filter must sample at least monthly for Cryptosporidium, E. coli, and
turbidity in their source water for 24 months, beginning 6 months after
promulgation of the LT2ESWTR. Large systems must submit a sampling
schedule to their primacy agency (in this case, EPA) no later than 3
months after promulgation of the LT2ESWTR.
Small surface water systems (fewer than 10,000 people served) that
filter must conduct biweekly E. coli sampling in their source water for
1 year, beginning 30 months after LT2ESWTR promulgation. States may
designate an alternate indicator monitoring strategy based on EPA
guidance, but compliance schedules will not change. Small systems that
exceed the indicator trigger value (i.e., mean E. coli £ 10/
100 mL for lake/reservoir sources or £ 50/100 mL for flowing
stream sources) must conduct source water Cryptosporidium sampling
twice-per-month for 1 year, beginning 48 months after LT2ESWTR
promulgation (i.e., beginning 6 months following the completion of E.
coli sampling). Small systems must submit an E. coli sampling schedule
to their primacy agency no later than 27 months after LT2ESWTR
promulgation. If Cryptosporidium monitoring is required, small systems
must submit a Cryptosporidium sampling schedule no later than 45 months
after LT2ESWTR promulgation.
Large systems must carry out a second round of source water
monitoring beginning 108 months after LT2ESWTR promulgation, which is 6
years after initial bin classification. Similarly, small systems must
conduct a second round of indicator monitoring (E. coli or other as
designated by the State) beginning 138 months after LT2ESWTR
promulgation, which is 6 years after their initial bin classification.
Small systems that exceed the indicator trigger value in the second
round of indicator monitoring must conduct a second round of
Cryptosporidium monitoring, beginning 156 months after LT2ESWTR
promulgation.
Compliance dates for filtered systems are summarized in Table IV-
23.

Table IV-23.--Summary of Compliance Dates for Filtered Systems
------------------------------------------------------------------------
System type Requirement Compliance date
------------------------------------------------------------------------
Large Systems (serve Submit sampling No later than 3
£=10,000 people). schedule 1,2. months after
promulgation.
Source water Begin monthly
Cryptosporidium, monitoring 6
E. coli and months after
turbidity promulgation for
monitoring. 24 months.
Comply with No later than 72
additional months after
Cryptosporidium promulgation.3
treatment
requirements.
Second round of Begin monthly
source water monitoring 108
Cryptosporidium, months after
E. coli, and promulgation for
turbidity 24 months.
monitoring 2.
Small Systems (serve <10,000 Submit E. coli No later than 27
people). sampling months after
schedule2. promulgation.
Source water E. Begin biweekly
coli monitoring. monitoring 30
months after
promulgation for
1 year.
Second round of Begin biweekly
source water E. monitoring 138
coli monitoring 2. months after
promulgation for
1 year.
---------------------
Additional requirements if indicator
(e.g., E. coli) trigger level is
exceeded4
---------------------
Submit No later than 45
Cryptosporidium months after
sampling schedule promulgation.
1,2.
Source water Begin twice-per-
Cryptosporidium month monitoring
monitoring. no later than 48
months after
promulgation for
1 year.
Comply with No later than 102
additional months after
Cryptosporidium promulgation.3, 5
treatment
requirements.
Second round of Begin twice-per-
source water month monitoring
Cryptosporidium no later than 156
monitoring. months after
promulgation for
1 year.
------------------------------------------------------------------------
\1\ Systems may be eligible to use previously collected (grandfathered)
data to meet LT2ESWTR requirements if specified quality control
criteria are met (described in section IV.A.1.d).
\2\ Systems are not required to monitor if they will provide at least
5.5 log Cryptosporidium treatment and notify EPA or the State.
\3\ States may grant up to an additional two years for systems making
capital improvements.
\4\ If the E. coli annual mean concentration exceeds 10/100 mL for
systems using lakes/reservoir sources or exceeds 50/100 mL for systems
using flowing stream sources, Cryptosporidium monitoring is required.
\5\ Systems that do not exceed the E. coli trigger level are classified
in Bin 1 and are not required to provide Cryptosporidium treatment
beyond LT1ESWTR levels.

ii. Unfiltered systems. Surface water systems that do not filter
and meet the criteria for avoidance of filtration (40 CFR 141.71)
(i.e., unfiltered systems) are required to conduct source water
Cryptosporidium monitoring to determine if their mean source water
Cryptosporidium level exceeds 0.01 oocysts/L. There is no E. coli
screening analysis available to small unfiltered systems. However, both
large and small unfiltered systems conduct

[[Page 47721]]

Cryptosporidium monitoring on the same schedule as filtered systems of
the same size. Note that unfiltered systems that currently provide or
will provide a total of at least 3 log Cryptosporidium inactivation are
exempt from monitoring requirements.
Large unfiltered systems (serving at least 10,000 people) must
conduct at least monthly Cryptosporidium sampling for 24 months,
beginning 6 months after LT2ESWTR promulgation. Small unfiltered
systems (serving fewer than 10,000 people) must conduct at least twice-
per-month Cryptosporidium sampling for 12 months, beginning 48 months
after LT2ESWTR promulgation. Large systems must submit a
Cryptosporidium sampling schedule to EPA no later than 3 months after
LT2ESWTR promulgation, and small systems must submit a sampling
schedule to their State no later than 45 months after LT2ESWTR
promulgation.
Unfiltered systems are required to conduct a second round of
Cryptosporidium monitoring on the same schedule as filtered systems of
the same size. Large systems must carry out a second round of
Cryptosporidium monitoring, beginning 108 months after LT2ESWTR
promulgation. Small systems must perform a second round of
Cryptosporidium monitoring, beginning 156 months after LT2ESWTR
promulgation.
Compliance dates for unfiltered systems are summarized in Table IV-
24.

Table IV-24.--Summary of Compliance Dates for Unfiltered Systems
------------------------------------------------------------------------
System type Requirement Compliance date
------------------------------------------------------------------------
Large Systems (serve Submit sampling No later than 3
£=10,000 people). schedule \1\. months after
promulgation.
Source water Begin monthly
Cryptosporidium monitoring [6
monitoring. months after
promulgation for
24 months.
Comply with No later than 72
Cryptosporidium months after
inactivation promulgation.\2\
requirements.
Second round of Begin monthly
source water monitoring 108
Cryptosporidium months after
monitoring. promulgation for
24 months.
Small Systems (serve < 10,000 Submit sampling No later than 45
people). schedule \1\. months after
promulgation.
Source water Begin twice-per-
Cryptosporidium month monitoring
monitoring. no later than 48
months after
promulgation for
1 year.
Comply with No later than 102
Cryptosporidium months after
inactivation promulgation.\2\
requirements.
Second round of Begin twice-per-
source water month monitoring
Cryptosporidium no later than 156
monitoring. months after
promulgation for
1 year.
------------------------------------------------------------------------
\1\ Systems may be eligible to use previously collected (grandfathered)
data to meet LT2ESWTR requirements if specified quality control
criteria are met (described in section IV.A.1.d).
\2\ States may grant up to an additional two years for systems making
capital improvements.

b. Treatment requirements. Filtered systems must determine their
bin classification and unfiltered systems must determine their mean
source water Cryptosporidium level within 6 months of the scheduled
month for collection of their final Cryptosporidium sample in the first
round of monitoring. This 6 month period provides time for systems to
receive all sample analysis results from the laboratory, analyze the
data, and work with their primacy agency.
Filtered systems have 3 years following initial bin classification
to meet any additional Cryptosporidium treatment requirements. This
equates to compliance dates of 72 months after LT2ESWTR promulgation
for large systems and 102 months after LT2ESWTR promulgation for small
systems (see Table IV-23). Unfiltered systems must comply with
Cryptosporidium treatment requirements on the same schedule as filtered
systems of the same size (see Table IV-24). The State may grant systems
an additional two years to comply when capital investments are
necessary, as specified in the Safe Drinking Water Act (section
1412(b)(10)).
Systems with uncovered finished water storage facilities are
required to comply with the provisions described in section IV.E by 36
months following LT2ESWTR promulgation, with the possibility of a 2
year extension granted by the State for systems making capital
improvements. Systems seeking approval for a risk mitigation plan must
submit the plan to the State within 24 months following LT2ESWTR
promulgation.
Systems must comply with additional Cryptosporidium treatment
requirements by implementing one or more treatment processes or control
strategies from the microbial toolbox. Most of the toolbox components
require submission of documentation to the State demonstrating
compliance with design and/or implementation criteria required to
receive credit. Compliance dates for reporting requirements associated
with microbial toolbox components are presented in detail in section
IV.J, Reporting and Recordkeeping Requirements.
c. Disinfection benchmarks for Giardia lamblia and viruses. Today's
proposed LT2ESWTR includes disinfection profiling and benchmarking
requirements, which consist of three major components: applicability
determination, characterization of disinfection practice, and State
review of proposed changes in disinfection practice. Each of these
components is discussed in detail in section IV.D. Compliance deadlines
associated with each of these components, including associated
reporting requirements, are stated in section IV.J, Reporting and
Recordkeeping Requirements.
2. How Was This Proposal Developed?
The compliance dates in today's proposal reflects the risk-targeted
approach of the proposed LT2ESWTR, wherein additional treatment
requirements are based on a system specific risk characterization as
determined through source water monitoring. Additionally, they are
designed to allow for systems to simultaneously comply with the
LT2ESWTR and Stage 2 DBPR in order to balance risks in the control of
microbial pathogens and DBPs. These dates are consistent with
recommendations from the Stage 2 M-DBP Federal Advisory Committee.
Under the LT2ESWTR, large systems will sample for Cryptosporidium
for a period of two years in order to

[[Page 47722]]

characterize source water pathogen levels and capture a degree of
annual variability. To expedite the date by which systems will provide
additional treatment where high risk source waters are identified,
large system Cryptosporidium monitoring will begin six months after
promulgation of the LT2ESWTR. Upon completion of Cryptosporidium
monitoring, systems will have six months to work with their primacy
agency to determine their bin classification. Beginning at this point,
which is three years following LT2ESWTR promulgation, large systems
will have three years to implement the treatment processes or control
strategies necessary to comply with any additional treatment
requirements stemming from bin classification.
Other large system compliance dates in areas like approval of
grandfathered monitoring data, disinfection profiling and benchmarking,
and reporting deadlines associated with microbial toolbox components
all stem from the Cryptosporidium monitoring and treatment compliance
schedule.
With respect to small systems under the LT2ESWTR, EPA is proposing
that small systems first monitor for E. coli as a screening analysis in
order to reduce the number of small systems that incur the cost of
Cryptosporidium monitoring. However, due to limitations in available
data, the Agency has determined that it is necessary to use data
generated by large systems under the LT2ESWTR to confirm or refine the
E. coli indicator criteria that will trigger small system
Cryptosporidium monitoring. Consequently, small system indicator
monitoring will begin at the conclusion of large system monitoring.
This approach was recommended by the Advisory Committee.
Accordingly, small systems will monitor for E. coli for one year,
beginning 30 months after LT2ESWTR promulgation. Following this, small
systems will have six months to determine if they are required to
monitor for Cryptosporidium and, if so, contract with an approved
analytical laboratory. Cryptosporidium monitoring by small systems will
be conducted for one year, which, when added to the one year of E. coli
monitoring, equals two years of source water monitoring. This is
equivalent to the time period large systems spend in source water
monitoring.
The time periods associated with bin assignment and compliance with
additional treatment requirements for small systems are the same as
those proposed for large systems. Specifically, small systems will have
six months to work with their States to determine their bin
classification following the conclusion of Cryptosporidium sampling.
From this point, which is 5.5 years after LT2ESWTR promulgation, small
systems have three years to meet any additional treatment requirements
resulting from bin classification. States can grant additional time to
small systems for compliance with treatment technique requirements
through granting exemptions (see SDWA section 1416).
3. Request for Comments
EPA requests comments on the treatment technique compliance
schedules for large and small systems in today's proposal, including
the following issues:
Time Window Between Large and Small System Monitoring
Under the current proposal, small filtered system E. coli
monitoring begins in the month following the end of large system
Cryptosporidium, E. coli, and turbidity monitoring. EPA plans to
evaluate large system monitoring results on an ongoing basis as the
data are reported to determine if any refinements to the E. coli levels
that trigger small system Cryptosporidium monitoring are necessary. If
such refinements were deemed appropriate, EPA would issue guidance to
States, which can establish alternative trigger values for small system
monitoring under the LT2ESWTR.
This implementation schedule does not leave any time between the
end of large system monitoring and the initiation of small system
monitoring. Consequently, if it is necessary to provide guidance on
alternative trigger values prior to when small system monitoring
begins, such guidance would be based on less than the full set of large
system results (e.g., first 18 months of large system data). EPA
requests comment on whether an additional time window between the end
of large system monitoring and the beginning of small system monitoring
is appropriate and, if so, how long such a window should be.
Implementation Schedule for Consecutive Systems
The Stage 2 M-DBP Agreement in Principle (65 FR 83015, December 29,
2000) (USEPA 2000a) continues the principle of simultaneous compliance
to address microbial pathogens and disinfection byproducts. Systems are
generally expected to address LT2ESTWR requirements concurrently with
those of the Stage 2 DBPR (as noted earlier, the Stage 2 DBPR is
scheduled to be proposed later this year and to be promulgated at the
same time as the LT2ESWTR).
As with the LT2ESWTR, small water systems (< 10,000 served)
generally begin monitoring and must be in compliance with the Stage 2
DBPR at a date later than that for large systems. However, the Advisory
Committee recommended that small systems that buy/receive from or sell/
deliver finished water to a large system (that is, they are part of the
same ``combined distribution system'') comply with Stage 2 DBPR
requirements on the same schedule as the largest system in the combined
distribution system. This approach is intended to ensure that systems
consider impacts throughout the combined distribution system when
making compliance decisions (e.g, selecting new technologies or making
operational modifications) and to facilitate all systems meeting the
compliance deadlines for the rule.
The issue of combined distribution systems associated with systems
buying and selling water is expected to be of less significance for the
LT2ESWTR. The requirements of the LT2ESWTR apply to systems treating
raw surface water and generally will not involve compliance steps when
systems purchase treated water. Consequently, the compliance schedule
for today's proposal does not address combined distribution systems.
However, this proposed approach raises the possibility that a small
system treating surface water and selling it to a large system could be
required to take compliance steps at an earlier date under the Stage 2
DBPR than under the LT2ESWTR. While a small system in this situation
could choose to comply with the LT2ESWTR on an earlier schedule, the
two rules would not require simultaneous compliance. EPA requests
comment on how this scenario should be addressed in the LT2ESWTR.

G. Public Notice Requirements

1. What Is EPA Proposing Today?
EPA is proposing that under the LT2ESWTR, a Tier 2 public notice
will be required for violations of additional treatment requirements
and a Tier 3 public notice will be required for violations of
monitoring and testing requirements. Where systems violate LT2ESWTR
treatment requirements, today's proposal requires the use of the
existing health effects language for microbiological contaminant
treatment technique violations, as stated in 40 CFR 141 Subpart Q,
Appendix B.

[[Page 47723]]

2. How Was This Proposal Developed?
In 2000, EPA published the Public Notification Rule (65 FR 25982,
May 4, 2000) (USEPA 2000d), which revised the general public
notification regulations for public water systems in order to implement
the public notification requirements of the 1996 SDWA amendments. This
regulation established the requirements that public water systems must
follow regarding the form, manner, frequency, and content of a public
notice. Public notification of violations is an integral part of the
public health protection and consumer right-to-know provisions of the
1996 SDWA Amendments.
Owners and operators of public water systems are required to notify
persons served when they fail to comply with the requirements of a
NPDWR, have a variance or exemption from the drinking water
regulations, or are facing other situations posing a risk to public
health. The public notification requirements divide violations into
three categories (Tier 1, Tier 2 and Tier 3) based on the seriousness
of the violations, with each tier having different public notification
requirements.
EPA has limited its list of violations and situations routinely
requiring a Tier 1 notice to those with a significant potential for
serious adverse health effects from short term exposure. Tier 1
violations contain language specified by EPA that concisely and in non-
technical terms conveys to the public the adverse health effects that
may occur as a result of the violation. States and water utilities may
add additional information to each notice, as deemed appropriate for
specific situations. A State may elevate to Tier 1 other violations and
situations with significant potential to have serious adverse health
effects from short-term exposure, as determined by the State.
Tier 2 public notices address other violations with potential to
have serious adverse health effects on human health. Tier 2 notices are
required for the following situations:
? All violations of the MCL, maximum residual disinfectant
level (MRDL) and treatment technique requirements, except where a Tier
1 notice is required or where the State determines that a Tier 1 notice
is required; and
? Failure to comply with the terms and conditions of any
existing variance or exemption.
Tier 3 public notices include all other violations and situations
requiring public notice, including the following situations:
? A monitoring or testing procedure violation, except where a
Tier 1 or 2 notice is already required or where the State has elevated
the notice to Tier 1 or 2; and
? Operation under a variance or exemption.
The State, at its discretion, may elevate the notice requirement
for specific monitoring or testing procedures from a Tier 3 to a Tier 2
notice, taking into account the potential health impacts and
persistence of the violation.
As part of the IESWTR, EPA established health effects language for
violations of treatment technique requirements for microbiological
contaminants. EPA believes this language, which was developed with
consideration of Cryptosporidium health effects, is appropriate for
violations of additional Cryptosporidium treatment requirements under
the LT2ESWTR.
3. Request for Comment
EPA requests comment on whether the violations of additional
treatment requirements for Cryptosporidium under the LT2ESWTR should
require a Tier 2 public notice and whether the proposed health effects
language is appropriate.

H. Variances and Exemptions

SDWA section 1415 allows States to grant variances from national
primary drinking water regulations under certain conditions; section
1416 establishes the conditions under which States may grant exemptions
to MCL or treatment technique requirements. For the reasons presented
in the following discussion, EPA has determined that systems will not
be eligible for variances or exemptions to the requirements of the
LT2ESWTR.
1. Variances
Section 1415 specifies two provisions under which general variances
to treatment technique requirements may be granted:
(1) A State that has primacy may grant a variance to a system from
any requirement to use a specified treatment technique for a
contaminant if the system demonstrates to the satisfaction of the State
that the treatment technique is not necessary to protect public health
because of the nature of the system's raw water source. EPA may
prescribe monitoring and other requirements as conditions of the
variance (section 1415(a)(1)(B)).
(2) EPA may grant a variance from any treatment technique
requirement upon a showing by any person that an alternative treatment
technique not included in such requirement is at least as efficient in
lowering the level of the contaminant (section 1415(a)(3)).
EPA does not believe the first provision for granting a variance is
applicable to the LT2ESWTR because Cryptosporidium treatment technique
requirements under this rule account for the degree of source water
contamination. Systems initially comply with the LT2ESWTR by conducting
source water monitoring for Cryptosporidium. Filtered systems are
required to provide additional treatment for Cryptosporidium only if
the source water concentration exceeds a level where current treatment
does not provide sufficient protection. All unfiltered systems are
required to provide a baseline of 2 log inactivation of Cryptosporidium
to achieve finished water risk levels comparable to filtered systems;
however, unfiltered systems are required to achieve 3 log inactivation
only if the source water level exceeds 0.01 oocysts/L.
The second provision for granting a variance is not applicable to
the LT2ESWTR because the treatment technique requirements of this rule
specify the degree to which systems must lower their source water
Cryptosporidium level (e.g., 4, 5, and 5.5 log reduction in Bins 2, 3,
and 4, respectively). The LT2ESWTR provides broad flexibility in how
systems achieve the required level of Cryptosporidium reduction, as
shown in the discussion of the microbial toolbox in section VI.C
Moreover, the microbial toolbox contains an option for Demonstration of
Performance, under which States can award treatment credit based on the
demonstrated efficiency of a treatment process in reducing
Cryptosporidium levels. Thus, there is no need for this type of
variance under the LT2ESWTR.
SDWA section 1415(e) describes small system variances, but these
cannot be granted for a treatment technique for a microbial
contaminant. Hence, small system variances are not allowed for the
LT2ESWTR.
2. Exemptions
Under SDWA section 1416(a), a State may exempt any public water
system from a treatment technique requirement upon a finding that (1)
due to compelling factors (which may include economic factors such as
qualification of the system as serving a disadvantaged community), the
system is unable to comply with the requirement or implement measures
to develop an alternative source of water supply; (2) the system was in
operation on the effective date of the treatment technique requirement,
or for a system that was not in operation by that date, no

[[Page 47724]]

reasonable alternative source of drinking water is available to the new
system; (3) the exemption will not result in an unreasonable risk to
health; and (4) management or restructuring changes (or both) cannot
reasonably result in compliance with the Act or improve the quality of
drinking water.
If EPA or the State grants an exemption to a public water system,
it must at the same time prescribe a schedule for compliance (including
increments of progress or measures to develop an alternative source of
water supply) and implementation of appropriate control measures that
the State requires the system to meet while the exemption is in effect.
Under section 1416(b)(2)(A), the schedule shall require compliance as
expeditiously as practicable (to be determined by the State), but no
later than three years after the otherwise applicable compliance date
for the regulations established pursuant to section 1412(b)(10). For
public water systems that do not serve more than a population of 3,300
and that need financial assistance for the necessary improvements, EPA
or the State may renew an exemption for one or more additional two-year
periods, but not to exceed a total of six years.
A public water system shall not be granted an exemption unless it
can establish that: (1) The system cannot meet the standard without
capital improvements that cannot be completed prior to the date
established pursuant to section 1412(b)(10); or (2) in the case of a
system that needs financial assistance for the necessary
implementation, the system has entered into an agreement to obtain
financial assistance pursuant to section 1452 or any other Federal or
state program; or (3) the system has entered into an enforceable
agreement to become part of a regional public water system.
EPA believes that granting an exemption to the Cryptosporidium
treatment requirements of the LT2ESWTR would result in an unreasonable
risk to health. As described in section II.C, Cryptosporidium causes
acute health effects, which may be severe in sensitive subpopulations
and include risk of mortality. Moreover, the additional Cryptosporidium
treatment requirements of the LT2ESWTR are targeted to systems with the
highest degree of risk. Due to these factors, EPA is not proposing to
allow exemptions under the LT2ESWTR.
3. Request for Comment
a. Variances. EPA requests comment on the determination that the
provisions for granting variances are not applicable to the proposed
LT2ESWTR, specifically including Cryptosporidium inactivation
requirements for unfiltered systems.
In theory it would be possible for an unfiltered system to
demonstrate raw water Cryptosporidium levels that were 3 log lower than
the cutoff for bin 1 for filtered systems and, thus, that it may be
providing comparable public health protection without additional
inactivation. However, EPA has determined that in practice it is not
currently economically or technologically feasible for systems to
ascertain the level of Cryptosporidium at this concentration. This is
due to the extremely large number and volume of samples that would be
necessary to make this demonstration with sufficient confidence. Based
on this determination and the Cryptosporidium occurrence data described
in section III.C, EPA is not proposing to allow unfiltered systems to
demonstrate raw water Cryptosporidium levels low enough to avoid
inactivation requirements. EPA requests comment on this approach.
b. Exemptions. EPA requests comment on the determination that
granting an exemption to the Cryptosporidium treatment requirements of
the LT2ESWTR would result in an unreasonable risk to health.

I. Requirements for Systems To Use Qualified Operators

The SWTR established a requirement that each public water system
using a surface water source or a ground water source under the direct
influence of surface water must be operated by qualified personnel who
meet the requirements specified by the State (40 CFR 141.70). The Stage
1 DBPR extended this requirement to include all systems affected by
that rule, and required that States maintain a register of qualified
operators (40 CFR 141.130(c)). While the proposed LT2ESWTR establishes
no new requirements regarding the operation of systems by qualified
personnel, the Agency would like to emphasize the important role that
qualified operators play in delivering safe drinking water to the
public. EPA encourages States that do not already have operator
certification programs in effect to develop such programs. States
should also review and modify, as required, their qualification
standards to take into account new technologies (e.g., ultraviolet
disinfection) and new compliance requirements.

J. System Reporting and Recordkeeping Requirements

1. Overview
Today's proposal includes reporting and recordkeeping requirements
associated with proposed monitoring and treatment requirements. As
described earlier, systems must conduct source water monitoring to
determine a treatment bin classification for filtered systems or a mean
Cryptosporidium level for unfiltered systems. Systems with previously
collected monitoring data may be able to use (i.e., grandfather) those
data in lieu of conducting new monitoring. Following source water
monitoring, systems will be required to comply with any additional
Cryptosporidium treatment requirements by implementing treatment and
control strategies from a microbial toolbox of options. Systems must
conduct a second round of source water monitoring six years after bin
classification.
In addition, systems using uncovered finished water storage
facilities must cover the facility or provide treatment unless the
system implements a State-approved risk management strategy. Certain
systems will be required to conduct disinfection profiling and
benchmarking.
The proposed rule requires public water systems to submit schedules
for Cryptosporidium, E. coli, and turbidity sampling at least 3 months
before monitoring must begin. Source water sample analysis results must
be reported not later than ten days after the end of first month
following the month when the sample is collected. As described later,
large systems (at least 10,000 people served) will report monitoring
results from the initial round of monitoring directly to EPA through an
electronic data system. Small systems will report monitoring results to
the State. Both small and large systems will report monitoring results
from the second round of monitoring to the State.
Systems must report a bin classification (filtered systems) or mean
Cryptosporidium level (unfiltered systems) within six months following
the month when the last sample in a particular round of monitoring is
scheduled to be collected. If systems are required to provide
additional treatment for Cryptosporidium, they must report regarding
the use of microbial toolbox components. Systems must notify the State
within 24 months following promulgation of the rule if they use
uncovered finished water storage facilities. Systems must also make
reports related to disinfection profiling and benchmarking. Reporting

[[Page 47725]]

requirements associated with these activities are summarized in Tables
IV-25 to IV-28.

Table IV-25.-- Summary of Initial Large Filtered System Reporting Requirements
----------------------------------------------------------------------------------------------------------------
You must report the following items On the following schedule
----------------------------------------------------------------------------------------------------------------
Sampling schedule for Cryptosporidium, E. coli, No later than 3 months after promulgation.
and turbidity monitoring.
Results of Cryptosporidium, E. coli, and turbidity No later than 10 days after the end of the first month
analyses. following the month in which the sample is collected.
Bin determination................................. No later than 36 months after promulgation.
Demonstration of compliance with additional Beginning 72 months after promulgation \1\ (See table IV-
treatment requirements. 34).
Disinfection profiling component reports.......... See Table IV-35.
----------------------------------------------------------------------------------------------------------------
\1\ States may grant an additional two years for systems making capital improvements.

Table IV-26.--Summary of Initial Small Filtered System Reporting Requirements
----------------------------------------------------------------------------------------------------------------
You must report the following items On the following schedule
----------------------------------------------------------------------------------------------------------------
Sampling schedule for E. coli monitoring.......... No later than 27 months after promulgation.
Results of E. coli analyses (unless State approves No later than 10 days after the end of the first month
a different indicator). following the month in which the sample was collected.
Mean E. coli concentration (unless State approves No later than 45 months after promulgation.
a different indicator).
Disinfection profiling component reports.......... See Table IV-36.
---------------------------------------------------
Additional requirements if E. coli trigger level is exceeded \1\
----------------------------------------------------------------------------------------------------------------
Sampling schedule for Cryptosporidium monitoring.. No later than 45 months after promulgation.
Results of Cryptosporidium analyses............... No later than 10 days after the end of the first month
following the month in which the sample is collected.
Bin determination................................. No later than 66 months after promulgation.
Demonstration of compliance with additional Beginning 102 months after promulgation \2\ (See Table IV-
treatment requirements. 34).
----------------------------------------------------------------------------------------------------------------
\1\ If the E. coli annual mean concentration exceeds 10/100 mL for systems using lakes/reservoirs or exceeds 50/
100 mL for systems using flowing streams, then systems must conduct Cryptosporidium monitoring. States may
approve alternative indicator criteria to trigger Cryptosporidium monitoring.
\2\ States may grant an additional two years for systems making capital improvements.

Table IV-27.--Summary of Initial Large Unfiltered System Reporting Requirements
----------------------------------------------------------------------------------------------------------------
You must report the following items On the following schedule
----------------------------------------------------------------------------------------------------------------
Cryptosporidium sampling schedule................. No later than 3 months after promulgation.
Results of Cryptosporidium analyses............... No later than 10 days after the end of the first month
following the month in which the sample was collected.
Determination of mean Cryptosporidium No later than 36 months after promulgation.
concentration.
Disinfection profiling component reports.......... See Table IV-35.
Demonstration of compliance with Cryptosporidium Beginning 72 months after promulgation \1\ (see Table IV-
inactivation requirements. 34).
----------------------------------------------------------------------------------------------------------------
\1\ States may grant an additional two years for systems making capital improvements.

Table IV-28.--Summary of Initial Small Unfiltered System Reporting Requirements
----------------------------------------------------------------------------------------------------------------
You must report the following items On the following schedule
----------------------------------------------------------------------------------------------------------------
Cryptosporidium sampling schedule................. No later than 45 months after promulgation.
Results of Cryptosporidium analyses............... No later than 10 days after the end of the first month
following the month in which the sample was collected.
Determination of mean Cryptosporidium No later than 66 months after promulgation.
concentration.
Disinfection profiling component reports.......... See Table IV-35.
Demonstration of compliance with Cryptosporidium Beginning 102 months after promulgation \1\ (see Table IV-
inactivation requirements. 34).
----------------------------------------------------------------------------------------------------------------
\1\ States may grant an additional two years for systems making capital improvements.

[[Page 47726]]

2. Reporting Requirements for Source Water Monitoring
a. Data elements to be reported. Proposed reporting requirements
for LT2ESWTR monitoring stem from proposed analytical method
requirements. As stated in sections IV.K and IV.L, systems must have
Cryptosporidium analyses conducted by EPA-approved laboratories using
Methods 1622 or 1623. E. coli analyses must be performed by State-
approved laboratories using the E. coli methods proposed for approval
in section IV.K. Systems are required to report the data elements
specified in Table IV-29 for each Cryptosporidium analysis. To comply
with LT2ESWTR requirements, only the sample volume filtered and the
number of oocysts counted must be reported for samples in which at
least 10 L is filtered and all of the sample volume is analyzed.
Additional information is required for samples where the laboratory
analyzes less than 10 L or less than the full sample volume collected.
Table IV-30 presents the data elements that systems must report for E.
coli analyses.
As described in the following section, EPA is developing a data
system to manage and analyze the microbial monitoring data that will be
reported by large systems under the LT2ESWTR. EPA is exploring
approaches for application of this data system to support small system
data reporting as well. Systems, or laboratories acting as the systems'
agents, must keep Method 1622/1623 bench sheets and slide examination
report forms until 36 months after an equivalent round of source water
monitoring has been completed (e.g., second round of Cryptosporidium
monitoring).

Table IV-29.--Proposed Cryptosporidium Data Elements to be Reported
----------------------------------------------------------------------------------------------------------------
Data element Reason for data element
----------------------------------------------------------------------------------------------------------------
Identifying information
----------------------------------------------------------------------------------------------------------------
? PWSID................................ Needed to associate plant with public water system.
? Facility ID.......................... Needed to associate sample result with facility.
? Sample collection point.............. Needed to associate sample result with sampling point.
? Sample collection date............... Needed to determine that utilities are collecting samples at the
frequency required.
? Sample type (field or matrix spike) Needed to distinguish field samples from matrix samples for
\1\. recovery calculations.
----------------------------------------------
Sample results
----------------------------------------------------------------------------------------------------------------
? Sample volume filtered (L), to Needed to verify compliance with sample volume requirements.
nearest \1/4\ L \2\.
? Was 100% of filtered volume examined? Needed to calculate the final concentration of oocysts/L and
\3\. determine if volume analyzed requirements are met.
? Number of oocysts counted............ Needed to calculate the final concentration of oocysts/L.
----------------------------------------------------------------------------------------------------------------
\1\ For matrix spike samples, sample volume spiked and estimated number of oocysts spiked must be reported.
These data are not required for field samples.
\2\ For samples in which <10 L is filtered or <100% of the sample volume is examined, the number of filters used
and the packed pellet volume must also be reported to verify compliance with LT2ESWTR sample volume analysis
requirements. These data are not required for most samples.
\3\ For samples in which <100% of sample is examined, the volume of resuspended concentrate and volume of this
resuspension processed through IMS must be reported to calculate the sample volume examined. These data will
not be required for most samples.

Table IV-30.--Proposed E. coli Data Elements to be Reported
----------------------------------------------------------------------------------------------------------------
Data element Reason for collecting data element
----------------------------------------------------------------------------------------------------------------
Identifying Information
----------------------------------------------------------------------------------------------------------------
PWS ID...................................... Needed to associate analytical result with public water system.
Facility ID................................. Needed to associate plant with public water system.
Sample collection point..................... Needed to associate sample result with sampling point.
Sample collection date...................... Needed to determine that utilities are collecting samples at the
frequency required.
Analytical method number.................... Needed to associate analytical result with analytical method.
Method Type................................. Needed to verify that an approved method was used and call up
correct web entry form.
Source water type........................... Needed to assess Cryptosporidium indicator relationships.
E. coli/100 mL.............................. Sample result (although not required, the laboratory also will
have the option of entering primary measurements for a sample
into the LT2ESWTR internet-based database to have the database
automatically calculate the sample result).
---------------------------------------------
Turbidity Information
----------------------------------------------------------------------------------------------------------------
Turbidity result............................ Needed to assess Cryptosporidium indicator relationships.
----------------------------------------------------------------------------------------------------------------

b. Data system. Because source water monitoring by large systems
(serving at least 10,000 people) will begin 6 months following
promulgation of the LT2ESWTR, EPA expects to act as the primacy agency
with oversight responsibility for large system sampling, analysis, and
data reporting. To facilitate collection and analysis of large system
monitoring data, EPA is developing an Internet-based electronic data
collection and management system. This approach is similar to that used
under the Unregulated Contaminants Monitoring Rule (UCMR) (64 FR 50556,
September 17, 1999) (USEPA 1999c).
Analytical results for Cryptosporidium, E. coli, and turbidity
analyses will be reported directly to this database using web forms and
software that can be downloaded free of charge.

[[Page 47727]]

The data system will perform logic checks on data entered and calculate
final results from primary data (where necessary). This is intended to
reduce reporting errors and limit the time involved in investigating,
checking, and correcting errors at all levels. EPA will make large
system monitoring data available to States when States assume primacy
for the LT2ESWTR or earlier under State agreements with EPA.
Large systems should instruct their laboratories to electronically
enter monitoring results into the EPA data system using web-based
manual entry forms or by uploading XML files from laboratory
information management systems (LIMS). After data are submitted by a
laboratory, systems may review the results on-line. If a system
believes that a result was entered into the data system erroneously,
the system may notify the laboratory to rectify the entry. In addition,
if a system believes that a result is incorrect, the system may submit
the result as a contested result and petition EPA or the State to
invalidate the sample. If a system contests a sample result, the system
must submit a rationale to the primacy agency, including a supporting
statement from the laboratory, providing a justification. Systems may
arrange with laboratories to review their sample results prior to the
results being entered into the EPA data system. Also, if a system
determines that its laboratory does not have the capability to report
data electronically, the system can submit a request to EPA to use an
alternate reporting format.
Regardless of the reporting process used, systems are required to
report an analytical monitoring result to the primacy agency no later
than 10 days after the end of the first month following the month when
the sample was collected. As described in section IV.A.1, if a system
is unable to report a valid Cryptosporidium analytical result for a
scheduled sampling date due to failure to comply with the analytical
method requirements (e.g., violation of quality control requirements),
the system must collect a replacement sample within 14 days of being
notified by the laboratory or the State that a result cannot be
reported for that date and must submit an explanation for the
replacement sample with the analytical results. A system will not incur
a monitoring violation if the State determines that the failure to
report a valid analysis result was due to circumstances beyond the
control of the system. However, in all cases the system must collect a
replacement sample.
The data elements to be collected by the electronic data system
will enhance the reliability of the microbial data generated under the
LT2ESWTR, while reducing the burden on the analytical laboratories and
public water systems. Tables IV-31 and IV-32 summarize the system's
data analysis functions for Cryptosporidium measurements.

Table IV-31.-- LT2ESWTR Data System Functions for Cryptosporidium Data
----------------------------------------------------------------------------------------------------------------
Applicability to sample types
Value calculated Formula -----------------------------------
Field Matrix spike
----------------------------------------------------------------------------------------------------------------
Calculation of sample volume (Volume filtered) * (resuspended Yes............. Yes.
analyzed. concentrate volume transferred to IMS/
resuspended concentrate volume).
Pellet volume analyzed......... (pellet volume)*(resuspended concentrated Yes............. Yes.
volume transferred to IMS/resuspended
concentrate volume).
Calculation of oocysts/L....... (Number of oocysts counted)/(sample volume Yes............. Yes.
analyzed).
Calculation of estimated number (Number of oocysts spiked)/(sample volume No.............. Yes.
of oocysts spiked/L. spiked).
Calculation of percent ((Calculated # of oocysts/L for the No.............. Yes.
recoveries for MS samples. MS sample)--(Calculated # of
oocysts/L in the associated field sample))
/ (Estimated number of oocysts spiked/L) *
100%.
----------------------------------------------------------------------------------------------------------------

Table IV-32.--LT2ESWTR Data System Functions for Cryptosporidium
Compliance Checks
------------------------------------------------------------------------
LT2 requirements Description
------------------------------------------------------------------------
Sample volume analysis....... Specifies that the LT2 requirements for
sample volume analyzed were met when:
? volume analyzed is £ 10
L.
? volume analyzed is < 10 L and
pellet volume analyzed is at least 2 mL.
? volume analyzed < 10 L and pellet
volume analyzed < 2 mL and 100% of
filtered volume examined= Y and two
filters were used.
Specifies that the LT2 requirements for
sample volume analyzed were not met
when:
? volume analyzed < 10 L and pellet
volume analyzed is < 2 mL and 100% of
filtered volume examined= N.
? volume analyzed is < 10 L and
pellet volume analyzed < 2 mL and only 1
filter used.
Schedule met................. Specifies that the predetermined sampling
schedule is met when the sample
collection data is within +/- 2 days of
the scheduled date.
------------------------------------------------------------------------

c. Previously collected monitoring data. Table IV-33 provides a
summary of the items that systems must report to EPA for consideration
of previously collected (grandfathered) monitoring data under the
LT2ESWTR. For each field and matrix spike (MS) sample, systems must
report the data elements specified in Table IV-29. In addition, the
laboratory that analyzed the samples must submit a letter certifying
that all Method 1622 and 1623 quality control requirements (including
ongoing precision and recovery (OPR) and method blank (MB) results,
holding times, and positive and negative staining controls) were
performed at the required frequency and were acceptable. Alternatively,
the laboratory may provide for each field, MS, OPR, and MB sample a
bench sheet and sample examination report form (Method 1622 and 1623
bench sheets are shown in USEPA 2003h).
Systems must report all routine source water Cryptosporidium
monitoring results collected during the

[[Page 47728]]

period covered by the previously collected data that have been
submitted. This applies to all samples that were collected from the
sampling location used for monitoring, not spiked, and analyzed using
the laboratory's routine process for Method 1622 or 1623 analyses,
including analytical technique and QA/QC. Other requirements associated
with use of previously collected data are specified in section
IV.A.1.d. Where applicable, systems must provide documentation
addressing the dates and reason(s) for re-sampling, as well as the use
of presedimentation, off-stream storage, or bank filtration during
monitoring. Review of the submitted information, along with the results
of the quality assurance audits of the laboratory that produced the
data, will be used to determine whether the data meet the requirements
for grandfathering.

Table IV-33.--Items That Must Be Reported for Consideration of Grandfathered Monitoring Data
----------------------------------------------------------------------------------------------------------------
The following items must be reported \1\ On the following schedule \1\
----------------------------------------------------------------------------------------------------------------
Data elements listed in Table IV-29 for each field and MS No later than 2 months after promulgation if
sample. the system does not intend to conduct new
monitoring under the LT2ESWTR.
Letter from laboratory certifying that method-specified QC was
performed at required frequency and was acceptable.
OR OR
Method 1622/1623 bench sheet and sample examination report form No later than 8 months after promulgation if
for each field, MS, OPR, and method blank sample. the system intends to conduct new monitoring
under the LT2ESWTR.
Letter from system certifying (1) that all source water data ...............................................
collected during the time period covered by the previously
collected data have been submitted and (2) that the data
represent the plant's current source water.
Where applicable, documentation addressing the dates and ...............................................
reason(s) for re-sampling, as well as the use of
presedimentation, off-stream storage, or bank filtration
during monitoring.
----------------------------------------------------------------------------------------------------------------
\1\ See section IV.A.1. for details.

3. Compliance With Additional Treatment Requirements
Under the proposed LT2ESWTR, systems may choose from a ``toolbox''
of management and treatment options to meet their additional
Cryptosporidium treatment requirements. In order to receive credit for
toolbox components, systems must initially demonstrate that they comply
with any required design and implementation criteria, including
performance validation testing. Additionally, systems must provide
monthly verification of compliance with any required operational
criteria, as shown through ongoing monitoring. Required design,
implementation, operational, and monitoring criteria for toolbox
components are described in section IV.C. Proposed reporting
requirements associated with these criteria are shown in Table IV-34
for both large and small systems.

Table IV-34.--Toolbox Reporting Requirements
----------------------------------------------------------------------------------------------------------------
On the following
Toolbox option (potential schedule \1\ On the following
Cryptosporidium reduction log You must submit the following items (systems serving schedule \1\
credit) £=10,000 (systems serving
people) < 10,000 people)
----------------------------------------------------------------------------------------------------------------
Watershed Control Program (WCP) Notify State of intention to develop No later than 48 No later than 78
(0.5 log) WCP. months after months after
Submit initial WCP plan to State...... promulgation promulgation.
No later than 60 No later than 90
months after months after
promulgation. promulgation.
Annual program status report and State- By a date determined By a date
approved watershed survey report. by the State, every determined by
12 months, the State, every
beginning 84 months 12 months,
after promulgation beginning 114
months after
promulgation.
Request for re-approval and report on No later than 6 No later than 6
the previous approval period. months prior to the months prior to
end of the current the end of the
approval period or current approval
by a date period or by a
previously date previously
determined by the determined by
State the State.
Pre-sedimentation (0.5 log) Monthly verification of: Monthly reporting Monthly reporting
(new basins) Continuous basin operation............ within 10 days within 10 days
Treatment of 100% of the flow......... following the month following the
Continuous addition of a coagulant.... in which the month in which
At least 0.5 log removal of influent monitoring was the monitoring
turbidity based on the monthly mean conducted, was conducted,
of daily turbidity readings for 11 of beginning 72 months beginning 102
the 12 previous months. after promulgation months after
promulgation.
Two-Stage Lime Softening (0.5 Monthly verification of: No later than 72 No later than 102
log) Continuous operation of a second months after months after
clarification step between the promulgation promulgation.
primary clarifier and filter.
Presence of coagulant (may be lime) in
first and second stage clarifiers.
Both clarifiers treat 100% of the
plant flow.

[[Page 47729]]

Bank filtration (0.5 or 1.0 Initial demonstration of: Initial Initial
log) (new) Unconsolidated, predominantly sandy demonstration no demonstration no
aquifer. later than 72 later than 102
Setback distance of at least 25 ft. months after months after
(0.5 log) or 50 ft. (1.0 log). promulgation promulgation.
If monthly average of daily max Report within 30 Report within 30
turbidity is greater than 1 NTU then days following the days following
system must report result and submit month in which the the month in
an assessment of the cause monitoring was which the
conducted, monitoring was
beginning 72 months conducted,
after promulgation beginning 102
months after
promulgation.
Combined filter performance Monthly verification of: Monthly reporting Monthly
(0.5 log) Combined filter effluent (CFE) within 10 days reporting:
turbidity levels less than or equal following the month within 10 days
to 0.15 NTU in at least 95 percent of in which the following the
the 4 hour CFE measurements taken monitoring was month in which
each month. conducted, the monitoring
beginning on 72 was conducted,
months after beginning on 102
promulgation months after
promulgation.
Membranes (MF, UF, NF, RO) (2.5 Initial demonstration of: No later than 72 No later than 102
log or greater based on Removal efficiency through challenge months after months after
verification/integrity studies. promulgation promulgation.
testing) Methods of challenge studies meet rule
criteria.
Integrity test results and baseline...
Monthly report summarizing: Within 10 days Within 10 days
All direct integrity test results following the month following the
above the control limit and the in which monitoring month in which
corrective action that was taken. was conducted, monitoring was
All indirect integrity monitoring beginning 72 months conducted,
results triggering direct integrity after promulgation beginning 102
testing and the corrective action months after
that was taken. promulgation.
Bag filters (1.0 log) and Initial demonstration that the No later than 72 No later than 102
Cartridge filters (2.0 log) following criteria are met: months after months after
Process meets the basic definition of promulgation promulgation.
bag or cartridge filtration;.
Removal efficiency established through
challenge testing that meets rule
criteria.
Challenge test shows at least 2 and 3
log removal for bag and cartridge
filters, respectively.
Chlorine dioxide (log credit Summary of CT values for each day and Within 10 days Within 10 days
based on CT) log inactivation based on tables in following the month following the
section IV.C.14 in which monitoring month in which
was conducted, monitoring was
beginning 72 months conducted,
after promulgation beginning 102
months after
promulgation.
Ozone (log credit based on CT) Summary of CT values for each day and Within 10 days Within 10 days
log inactivation based on tables in following the month following the
section IV.C.14 in which monitoring month in which
was conducted, monitoring was
beginning 72 months conducted,
after promulgation beginning 102
months after
promulgation.
UV (log credit based UV dose Results from reactor validation No later than 72 No later than 102
and operating within validated testing demonstrating operating months after months after
conditions) conditions that achieve required UV promulgation promulgation.
dose
Monthly report summarizing the Within 10 days Within 10 days
percentage of water entering the following the month following the
distribution system that was not in which monitoring month in which
treated by UV reactors operating was conducted, monitoring was
within validated conditions for the beginning 72 months conducted,
required UV dose in section IV.C.15 after promulgation beginning 102
months after
promulgation.
Individual filter performance Monthly verification of the following, Monthly reporting Monthly
(1.0 log) based on continuous monitoring of within 10 days reporting:
turbidity for each individual filter: following the month within 10 days
Filtered water turbidity less than 0.1 in which the following the
NTU in at least 95 percent of the monitoring was month in which
daily maximum values from individual conducted, the monitoring
filters (excluding 15 minute period beginning on 72 was conducted,
following start up after backwashes). months after beginning 102
No individual filter with a measured promulgation months after
turbidity greater than 0.3 NTU in two promulgation.
consecutive measurements taken 15
minutes apart.
Demonstration of Performance Results from testing following State No later than 72 No later than 102
approved protocol. months after months after
promulgation promulgation.

[[Page 47730]]

Monthly verification of operation Within 10 days Within 10 days
within State-approved conditions for following the month following the
demonstration of performance credit in which monitoring month in which
was conducted, monitoring was
beginning 72 months conducted,
after promulgation beginning 102
months after
promulgation.
----------------------------------------------------------------------------------------------------------------
\1\ States may allow an additional two years for systems making capital improvements.

Reporting requirements associated with disinfection profiling and
benchmarking are summarized in Table IV-35 for large systems and in
Table IV-36 for small systems.

Table IV-35.--Disinfection Benchmarking Reporting Requirements for Large Systems
----------------------------------------------------------------------------------------------------------------
Submit the following On the following
System type Benchmark component items schedule
----------------------------------------------------------------------------------------------------------------
Systems required to conduct Characterization of Giardia lamblia and No later than 36
Cryptosporidium monitoring. Disinfection Practices. virus inactivation months after
profiles must be on promulgation.
file for State review
during sanitary
survey.
State Review of Proposed Inactivation profiles Prior to significant
Changes to Disinfection and benchmark modification of
Practices. determinations. disinfection
practice.
Systems not required to conduct Applicability.............. None.................. None.
Cryptosporidium monitoring\1\.
Characterization of None.................. None.
Disinfection Practices.
State Review of Proposed None.................. None.
Changes to Disinfection
Practices.
----------------------------------------------------------------------------------------------------------------
\1\Systems that provide at least 5.5 log of Cryptosporidium treatment consistent with a Bin 4 treatment
implication are not required to conduct Cryptosporidium monitoring.

Table IV-36.--Disinfection Benchmarking Reporting Requirements for Small Systems
----------------------------------------------------------------------------------------------------------------
Submit the following On the following
System type Benchmark component items schedule
----------------------------------------------------------------------------------------------------------------
Systems required to conduct Characterization of Giardia lamblia and No later than 66
Cryptosporidium monitoring. Disinfection Practices. virus inactivation months after
profiles must be on promulgation.
file for State review
during sanitary
survey.
State Review of Proposed Inactivation profiles Prior to significant
Changes to Disinfection and benchmark modification of
Practices. determinations. disinfection
practice.
Systems not required to conduct Applicability Period....... Notify State that No later than 42
Cryptosporidium monitoring and profiling is required months after
that exceed DBP triggers\1,2,3\. based on DBP levels. promulgation.
Characterization of Giardia lamblia and No later than 54
Disinfection Practices. virus inactivation months after
profiles must be on promulgation.
file for State review
during sanitary
survey.
State Review of Proposed Inactivation profiles Prior to significant
Changes to Disinfection and benchmark modification of
Practices. determinations. disinfection
practice.
Systems not required to conduct Applicability Period....... Notify State that No later than 42
Cryptosporidium monitoring and profiling is not months after
that do not exceed DBP required based on DBP promulgation.
triggers\2,3\. levels.
Characterization of None.................. None.
Disinfection Practices.
State Review of Proposed None.................. None.
Changes to Disinfection
Practices.
----------------------------------------------------------------------------------------------------------------
\1\ Systems that provide at least 5.5 log of Cryptosporidium treatment consistent with a Bin 4 treatment
implication are not required to conduct Cryptosporidium monitoring.
\2\ If the E. coli annual mean concentration is <= 10/100 mL for systems using lakes/reservoir sources or <= 50/
100 mL for systems using flowing stream sources, the system is not required to conduct Cryptosporidium
monitoring and will only be required to characterize disinfection practices if DBP triggers are exceeded.

[[Page 47731]]

\3\ If the system is a CWS or NTNCWSs and TTHM or HAA5 levels in the distribution system are at least 0.064 mg/L
or 0.048 mg/L, respectively, calculated as an LRAA at any Stage 1 DBPR sampling site, then the system is
triggered into disinfection profiling.

4. Request for Comment
EPA requests comment on the reporting and recordkeeping
requirements proposed for the LT2ESWTR.
Specifically, the Agency requests comment on the proposed
requirement that systems report monthly on the use of microbial toolbox
components to demonstrate compliance with their Cryptosporidium
treatment requirements. An alternative may be for systems to keep
records on site for State review instead of reporting the data.

K. Analytical Methods

EPA is proposing to require public water systems to conduct
LT2ESWTR monitoring using approved methods for Cryptosporidium, E.
coli, and turbidity analyses. This includes meeting quality control
criteria stipulated by the approved methods and additional method-
specific requirements, as stated later in this section. Related
requirements on the use of approved laboratories are discussed in
section IV.L, and proposed requirements for reporting of data were
stated previously in section IV.J. EPA has developed draft guidance for
sampling and analyses under the LT2ESWTR (see USEPA 2003g and 2003h).
This guidance is available in draft form in the docket for today's
proposal (http://www.epa.gov/edocket/).

1. Cryptosporidium
a. What is EPA proposing today? Method 1622: ``Cryptosporidium in
Water by Filtration/IMS/FA'' (EPA-821-R-01-026, April 2001) (USEPA
2001e) and Method 1623: ``Cryptosporidium and Giardia in Water by
Filtration/IMS/FA'' (EPA 821-R-01-025, April 2001) (USEPA 2001f) are
proposed for Cryptosporidium analysis under this rule. Methods 1622 and
1623 require filtration, immunomagnetic separation (IMS) of the oocysts
from the captured material, and examination based on IFA, DAPI staining
results, and differential interference contrast (DIC) microscopy for
determination of oocyst concentrations.
Method Requirements
For each Cryptosporidium sample under this proposal, all systems
must analyze at least a 10-L sample volume. Systems may collect and
analyze greater than a 10-L sample volume. If a sample is very turbid,
it may generate a large packed pellet volume upon centrifugation (a
packed pellet refers to the concentrated sample after centrifugation
has been performed in EPA Methods 1622 and 1623). Based on IMS
purification limitations, samples resulting in large packed pellets
will require that the sample concentrate be aliquoted into multiple
``subsamples'' for independent processing through IMS, staining, and
examination. Because of the expense of the IMS reagents and analyst
time to examine multiple slides per sample, systems are not required to
analyze more than 2 mL of packed pellet volume per sample.
In cases where it is not feasible for a system to process a 10-L
sample for Cryptosporidium analysis (e.g., filter clogs prior to
filtration of 10 L) the system must analyze as much sample volume as
can be filtered by 2 filters, up to a packed pellet volume of 2 mL.
This condition applies only to filters that have been approved by EPA
for nationwide use with Methods 1622 and 1623--the Pall Gelman
EnvirochekTM and EnvirochekTM HV filters, the
IDEXX Filta-MaxTM foam filter, and the Whatman
CrypTestTM cartridge filter.
Methods 1622 and 1623 include fluorescein isothiocyanate (FITC) as
the primary antibody stain for Cryptosporidium detection, DAPI staining
to detect nuclei, and DIC to detect internal structures. For purposes
of the LT2ESWTR, systems must report total Cryptosporidium oocysts as
detected by FITC as determined by the color (apple green or alternative
stain color approved for the laboratory under the Lab QA Program
described in section VI.L), size (4-6 [mu]m) and shape (round to oval).
This total includes all of the oocysts identified as described here,
less atypical organisms identified by FITC, DIC, or DAPI (e.g.,
possessing spikes, stalks, appendages, pores, one or two large nuclei
filling the cell, red fluorescing chloroplasts, crystals, spores,
etc.).
Matrix Spike Samples
As required by Method 1622 and 1623, systems must have 1 matrix
spike (MS) sample analyzed for each 20 source water samples. The volume
of the MS sample must be within ten percent of the volume of the
unspiked sample that is collected at the same time, and the samples
must be collected by splitting the sample stream or collecting the
samples sequentially. The MS sample and the associated unspiked sample
must be analyzed by the same procedure. MS samples must be spiked and
filtered in the laboratory. However, if the volume of the MS sample is
greater than 10 L, the system is permitted to filter all but 10 L of
the MS sample in the field, and ship the filtered sample and the
remaining 10 L of source water to the laboratory. In this case, the
laboratory must spike the remaining 10 L of water and filter it through
the filter used to collect the balance of the sample in the field.
EPA is proposing to require the use of flow cytometer-counted
spiking suspensions for spiked QC samples during the LT2ESWTR. This
provision is based on the improved precision expected for spiking
suspensions counted with a flow cytometer, as compared to those counted
using well slides or hemacytometers. During the Information Collection
Rule Supplemental Surveys, the mean relative standard deviation (RSD)
across 25 batches of flow cytometer-sorted Cryptosporidium spiking
suspensions was 1.8%, with a median of 1.7% (Connell et al. 2000). In
EPA Performance Evaluation (PE) studies, the mean RSD for flow
cytometer sorted Cryptosporidium spiking suspensions was 3.4%. In
comparison, the mean RSD for Cryptosporidium spiking suspensions
enumerated manually by 20 laboratories using well slides or
hemacytometers was 17% across 108 rounds of 10-replicate counts.
QC requirements in Methods 1622 and 1623 must be met by
laboratories analyzing Cryptosporidium samples under the LT2ESWTR. The
QC acceptance criteria are the same as stipulated in the method. For
the initial precision and recovery (IPR) test, the mean Cryptosporidium
recovery must be 24% to 100% with maximum relative standard deviation
(i.e., precision) of 55%. For each ongoing precision and recovery (OPR)
sample, recovery must be in the range of 11% to 100%. For each method
blank, oocysts must be undetected.
Methods 1622 and 1623 are performance-based methods and, therefore,
allow multiple options to perform the sample processing steps in the
methods if a laboratory can meet applicable QC criteria and uses the
same determinative technique. If a laboratory uses the same procedures
for all samples, then all field samples and QC samples must be analyzed
in that same manner. However, if a laboratory uses more than one set of
procedures for Cryptosporidium analyses under LT2ESWTR then the
laboratory must analyze separate QC samples for each

[[Page 47732]]

option to verify compliance with the QC criteria. For example, if the
laboratory analyzes samples using both the EnvirochekTM and
Filta-MaxTM filters, a separate set of IPR, OPR, method
blank, and MS samples must be analyzed for each filtration option.
b. How was this proposal developed? EPA is proposing EPA Methods
1622 and 1623 for Cryptosporidium analyses under the LT2ESWTR because
these are the best available methods that have undergone full
validation testing. In addition, these methods have been used
successfully in a national source water monitoring program as part of
the Information Collection Rule Supplemental Surveys (ICRSS). The
minimum sample volume and other quality control requirements are
intended to ensure that data are of sufficient quality to assign
systems to LT2ESWTR risk bins. Further, the proposed method
requirements for analysis of Cryptosporidium are consistent with
recommendations by the Stage 2 M-DBP Advisory Committee. In the
Agreement in Principle, the Committee recommended that source water
Cryptosporidium monitoring under the LT2ESWTR be conducted using EPA
Methods 1622 and 1623 with no less than 10 L samples. EPA also has
proposed these methods for approval for ambient water monitoring under
Guidelines Establishing Test Procedures for the Analysis of Pollutants;
Analytical Methods for Biological Pollutants in Ambient Water (66 FR
45811, August 30, 2001) (USEPA 2001i).
When considering the method performance that could be achieved for
analysis of Cryptosporidium under the LT2ESWTR, EPA and the Advisory
Committee evaluated the Cryptosporidium recoveries reported for Methods
1622 and 1623 in the ICRSS. As described in section III.C, the ICRSS
was a national monitoring program that involved 87 utilities sampling
twice per month over 1 year for Cryptosporidium and other
microorganisms and water quality parameters. During the ICRSS, the mean
recovery and relative standard deviation associated with enumeration of
MS samples for total oocysts by Methods 1622 and 1623 were 43% and 47%,
respectively (Connell et al. 2000).
EPA believes that with provisions like the Laboratory QA Program
for Cryptosporidium laboratories (see section IV.L), comparable
performance to that observed in the ICRSS can be achieved in LT2ESWTR
monitoring with the use of Methods 1622 and 1623, and that this level
of performance will be sufficient to realize the public health goals
intended by EPA and the Advisory Committee for the LT2ESWTR. Other
methods would need to achieve comparable performance to be considered
for use under the LT2ESWTR. For example, EPA does not expect the
Information Collection Rule Method, which resulted in 12% mean recovery
for MS samples during the Information Collection Rule Laboratory
Spiking Program (Scheller, 2002), to meet LT2ESWTR data quality
objectives.
For systems collecting samples larger than 10 L, EPA is proposing
the approach of allowing systems to filter all but 10 L of the
corresponding MS sample in the field, and ship the filtered sample and
the remaining 10 L of source water to the laboratory for spiking and
analysis. The Agency has determined that the added costs associated
with shipping entire high-volume (e.g. 50-L) samples to a laboratory
for spiking and analysis are not merited by improved data quality
relative to the use of Cryptosporidium MS data under the LT2ESWTR. EPA
estimates that the average cost for shipping a 50-L bulk water sample
is $350 more than the cost of shipping a 10-L sample and a filter. A
study comparing these two approaches (i.e., spiking and filtering 50 L
vs. field filtering 40 L and spiking 10 L) indicated that spiking the
10-L sample produced somewhat higher recoveries (USEPA 2003i). However,
the differences were not significant enough to offset the greatly
increased shipping costs, given the limited use of MS data in LT2ESWTR
monitoring.
c. Request for comment. EPA requests comment on the proposed method
requirements for Cryptosporidium analysis, including the following
specific issues:
Minimum Sample Volume
It is the intent of EPA that LT2ESWTR sampling provide
representative annual mean source water concentrations. If systems were
unable to analyze an entire sample volume during certain periods of the
year due to elevated turbidity or other water quality factors, this
could result in systems analyzing different volumes in different
samples. Today's proposal requires systems to analyze at least 10 L of
sample or the maximum amount of sample that can be filtered through two
filters, up to a packed pellet volume of 2 mL. EPA requests comment on
whether these requirements are appropriate for systems with source
waters that are difficult to filter or that generate a large packed
pellet volume. Alternatively, systems could be required to filter and
analyze at least 10 L of sample with no exceptions.
Approval of Updated Versions of EPA Methods 1622 and 1623
EPA has developed draft revised versions of EPA Methods 1622 and
1623 in order to consolidate several method-related changes EPA
believes may be necessary to address LT2ESWTR monitoring requirements
(see USEPA 2003j and USEPA 2003k). EPA is requesting comment on whether
these revised versions should be approved for monitoring under the
LT2ESWTR, rather than the April 2001 versions proposed in today's rule.
If the revised versions were approved, previously collected data
generated using the earlier versions of the methods would still be
acceptable for grandfathering, provided the other criteria described in
section IV.A.1.d were met. Drafts of the updated methods are provided
in the docket for today's rule, and differences between these versions
and the April 2001 versions of the methods are clearly indicated for
evaluation and comment. Changes to the methods include the following:

(1) Increased flexibility in matrix spike (MS) and initial
precision and recovery (IPR) requirements--the requirement that the
laboratory must analyze an MS sample on the first sampling event for
a new PWS would be changed to a recommendation; the revised method
would allow the IPR test to be performed across four different days,
rather than restrict analyses to 1 day;
(2) Clarification of some method procedures, including the
spiking suspension vortexing procedure and the buffer volumes used
during immunomagnetic separation (IMS); requiring (rather than
recommending) that laboratories purchase HCl and NaOH standards at
the normality specified in the method; and clarification that the
use of methanol during slide staining in section 14.2 of the method
is as per manufacturer's instructions;
(3) Additional recommendations for minimizing carry-over of
debris onto microscope slides after IMS and information on
microscope cleaning;
(4) Clarification in the method of the actions to take in the
event of QC failures, such as that any positive sample in a batch
associated with an unacceptable method blank is unacceptable and
that any sample in a batch associated with an unacceptable ongoing
precision and recovery (OPR) sample is unacceptable;
(5) Changes to the sample storage and shipping temperature to
``less than 10[deg]C and not frozen'', and additional guidance on
sample storage and shipping procedures that addresses time of
collection, and includes suggestions for monitoring sample
temperature during shipment and upon receipt at the laboratory.
(6) Additional analyst verification procedures--adding
examination using differential interference contrast (DIC)
microscopy to the analyst verification requirements.

[[Page 47733]]

(7) Addition of an approved method modification using the Pall
Gelman Envirochek HV filter. This approval was based on an
interlaboratory validation study demonstrating that three
laboratories, each analyzing reagent water and a different source
water, met all method acceptance criteria for Cryptosporidium. EPA
issued a letter (dated March 21, 2002) under the Alternative Test
Procedures program approving the procedure as an acceptable version
of Method 1623 for Cryptosporidium (but not for Giardia). EPA also
noted in the letter that the procedure was considered to be an
acceptable modification of EPA Method 1622.
(8) Incorporation of detailed procedures for concentrating
samples using an IDEXX Filta-MaxTM foam filter. A method
modification using this filter already is approved by EPA in the
April 2001 versions of the methods.
(9) Addition of BTF EasySeedTM irradiated oocysts and
cysts as acceptable materials for spiking routine QC samples. EPA
approved the use of EasySeedTM based on side-by-side
comparison tests of method recoveries using EasySeedTM
and live, untreated organisms. EPA issued a letter (dated August 1,
2002) approving EasySeedTM for use in routine QC samples
for EPA Methods 1622 and 1623 and for demonstrating comparability of
method modifications in a single laboratory.
(10) Removal of the Whatman Nuclepore CrypTestTM
cartridge filter. Although a method modification using this filter
was approved by EPA in the April 2001 versions of the methods, the
filter is no longer available from the manufacturer, and so is no
longer an option for sample filtration.

The changes in the June 2003 draft revisions of EPA Methods 1622
and 1623 reflect method-related clarifications, modifications, and
additions that EPA believes should be addressed for LT2ESWTR
Cryptosporidium monitoring. Alternatively, these issues could be
addressed through regulatory requirements in the final LT2ESWTR (for
required changes and additions) and through guidance (for recommended
changes and clarifications). However, EPA believes that addressing
these issues through a single source in updated versions of EPA Methods
1622 and 1623 (which could be approved in the final LT2ESWTR) may be
more straightforward and easier for systems and laboratories to follow
than addressing them in multiple sources (i.e., existing methods, the
final rule, and laboratory guidance).
2. E. coli
a. What is EPA proposing today? For enumerating source water E.
coli density under the LT2ESWTR, EPA is proposing to approve the same
methods that were proposed by EPA under Guidelines Establishing Test
Procedures for the Analysis of Pollutants; Analytical Methods for
Biological Pollutants in Ambient Water (66 FR 45811, August 30, 2001)
(USEPA 2001i). These methods are summarized in Table IV-37. Methods are
listed within the general categories of most probable number tests and
membrane filtration tests. Method identification numbers are provided
for applicable standards published by EPA and voluntary consensus
standards bodies (VCSB) including Standard Methods, American Society of
Testing Materials (ASTM), and the Association of Analytical Chemists
(AOAC).

Table IV-37.-- Proposed Methods for E. Coli Enumeration \1\
--------------------------------------------------------------------------------------------------------------------------------------------------------
VCSB methods
---------------------------------------
Technique Method\1\ EPA Standard Commercial example
methods\2\ ASTM\3\ AOAC\4\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Most Probable Number (MPN)... LTB, EC-MUG...................... ............ 9221B.1/
9221F
ONPG-MUG......................... ............ 9223B ........... 991.15 Colilert[reg]\5\.
ONPG-MUG......................... ............ 9223B ........... ........... Colilert-18[reg]5 7.
Membrane Filter (MF)......... mFC[rtarr3]NA-MUG................ ............ 9222D/
9222G
mENDO or LES-ENDO[rtarr3]NA-MUG.. ............ 9222B/
9222G
mTEC agar........................ 1103.1 9213D D5392-93
Modified mTEC agar............... 1603
MI medium........................ 1604
m-ColiBlue24 broth............... ............ ........... ........... ........... m-ColiBlue24\6\.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Tests must be conducted in a format that provides organism enumeration.
\2\ Standard Methods for the Examination of Water and Wastewater. American Public Health Association. 20th, 19th, and 18th Editions. Amer. Publ. Hlth.
Assoc., Washington, DC.
\3\ Annual Book of ASTM Standards--Water and Environmental Technology. Section 11.02. ASTM. 100 Barr Harbor Drive, West Conshohocken, PA 19428.
\4\ Official Methods of Analysis of AOAC International, 16th Edition, Volume I, Chapter 17. AOAC International. 481 North Frederick Avenue, Suite 500,
Gaithersburg, Maryland 20877-2417.
\5\ Manufactured by IDEXX Laboratories, Inc., One IDEXX Drive, Westbrook, Maine 04092.
\6\ Manufactured by Hach Company, 100 Dayton Ave., Ames, IA 50010.
\7\ Acceptable version of method approved as a drinking water alternative test procedure.

EPA is proposing to allow a holding time of 24 hours for E. coli
samples. The holding time refers to the time between sample collection
and initiation of analysis. Currently, 40 CFR 141.74(a) limits the
holding time for source water coliform samples to 8 hours and requires
that samples be kept below 10[deg]C during transit. EPA believes that
new studies, described later in this section, demonstrate that E. coli
analysis results for samples held for 24 hours will be comparable to
samples held for 8 hours, provided the samples are held below 10[deg]C
and are not allowed to freeze. This proposed increase in holding time
is significant for the LT2ESWTR because typically it is not feasible
for systems to meet an 8-hour holding time when samples cannot be
analyzed on-site. Many small systems that will conduct E. coli
monitoring under the LT2ESWTR lack a certified on-site laboratory for
E. coli analyses and will be required to ship samples to a certified
laboratory. EPA believes that it is feasible for these systems to
comply with a 24 hour holding time for E. coli samples through using
overnight delivery services.
b. How was this proposal developed? As noted, EPA recently proposed
methods for ambient water E. coli analysis under Guidelines
Establishing Test Procedures for the Analysis of Pollutants; Analytical
Methods for

[[Page 47734]]

Biological Pollutants in Ambient Water (66 FR 45811, August 30, 2001)
(USEPA 2001i). These proposed methods were selected based on data
generated by EPA laboratories, submissions to the alternate test
procedures (ATP) program and voluntary consensus standards bodies,
published peer reviewed journal articles, and publicly available study
reports.
The source water analysis for E. coli that will be conducted under
the LT2ESWTR is similar to the type of ambient water analyses for which
these methods were previously proposed (66 FR 45811, August 30, 2001)
(USEPA 2001i). EPA continues to support the findings of this earlier
proposal and believes that these methods have the necessary sensitivity
and specificity to meet the data quality objectives of the LT2ESWTR.
New Information on E. coli Sample Holding Time
It is generally not feasible for systems that must ship E. coli
samples to an off-site laboratory to comply with an 8-hour holding time
requirement. During the ICRSS, 100% of the systems that shipped samples
off-site for E. coli analysis exceeded the 8 hour holding time; 12% of
these samples had holding times in excess of 30 hours. Most large
systems that will be required to monitor for E. coli under the LT2ESWTR
could conduct these analyses on-site, but many small systems will need
to ship samples off-site to a certified contract laboratory.
EPA participated in three phases of studies to assess the effect of
increased sample holding time on E. coli analysis results. These are
summarized as follows, and are described in detail in Pope et al.
(2003).
? Phase 1-EPA, the Wisconsin State Laboratory of Hygiene
(WSLH), and DynCorp conducted a study to evaluate E. coli sample
concentrations from four sites at 8, 24, 30, and 48 hours after sample
collection for samples stored at 4[deg]C, 10[deg]C, 20[deg]C, and
35[deg]C. Temperature was varied to assess the effect of different
shipping conditions. Samples were analyzed in triplicate by membrane
filtration (mFC followed by transfer to NA-MUG) and Colilert (Quanti-
Tray 2000) (Pope et al. 2003).
? Phase 2-EPA conducted a study to evaluate E. coli sample
concentrations from seven sites at 8, 24, 30, and 48 hours after sample
collection for samples stored in coolers containing wet ice or Utek ice
packs (to assess real-world storage conditions). Samples were analyzed
in triplicate by membrane filtration (mFC followed by transfer to NA-
MUG) and Colilert (Quanti-Tray 2000) (Pope et al. 2003).
? Phase 3-EPA, through cooperation with AWWA, obtained E.
coli holding time data from ten drinking water utilities that evaluated
samples from 12 source waters. Each utility used an E. coli method of
its choice (Colilert, mTEC, mEndo to NA-MUG, or mFC to NA-MUG). Samples
were stored in coolers with wet ice, Utek ice packs, or Blue ice (Pope
et al. 2003).
Phase 1 results indicated that E. coli concentrations were not
significantly different after 24 hours at most sites when samples were
stored at lower temperatures. Results from Phase 2, which evaluated
actual sample storage practices, verified the Phase 1 observations at
most sites. Similar results were observed during Phase 3, which
evaluated a wider variety of surface waters from different regions
throughout the U.S. During Phase 3, E. coli concentrations were not
significantly different after 24 hours at most sites when samples were
maintained below 10[deg]C and did not freeze during storage. At longer
holding times (e.g., 48 hours), larger differences were observed.
Based on these studies, EPA has concluded that E. coli samples can
be held for up to 24 hours prior to analysis without compromising the
data quality objectives of LT2ESWTR E. coli monitoring. Further, EPA
believes that it is feasible for systems that must ship E. coli samples
to an off-site laboratory for analysis to meet a 24 hour holding time.
EPA is developing guidance for systems on packing and shipping E. coli
samples so that samples are maintained below 10[deg]C and not allowed
to freeze (USEPA 2003g). This guidance is available in draft in the
docket for today's proposal (http://www.epa.gov/edocket/).
c. Request for comment. EPA requests comment on whether the E. coli
methods proposed for approval under the LT2ESWTR are appropriate, and
whether there are additional methods not proposed that should be
considered. Comments concerning method approval should be accompanied
by supporting data where possible.
EPA also requests comment on the proposal to extend the holding
time for E. coli source water sample analyses to 24 hours, including
any data or other information that would support, modify, or repudiate
such an extension. Should EPA limit the extended holding time to only
those E. coli analytical methods that were evaluated in the holding
time studies noted in this section? The results in Pope et al. (2003)
indicate that most E. coli samples analyzed using ONPG-MUG (see methods
in Table IV-37) incurred no significant degradation after a 30 to 48
hour holding time. As a result, should EPA increase the source water E.
coli holding time to 30 or 48 hours for samples evaluated by ONPG-MUG,
and retain a 24-hour holding time for samples analyzed by other
methods? EPA also requests comment on the cost and availability of
overnight delivery services for E. coli samples, especially in rural
areas.
3. Turbidity
a. What is EPA proposing today? For turbidity analyses that will
be conducted under the LT2ESWTR, EPA is proposing to require systems to
use the analytical methods that have been previously approved by EPA
for analysis of turbidity in drinking water, as listed in 40 CFR Part
141.74. These are Method 2130B as published in Standard Methods for the
Examination of Water and Wastewater (APHA 1992), EPA Method 180.1
(USEPA 1993), and Great Lakes Instruments Method 2 (Great Lakes
Instruments, 1992), and Hach FilterTrak Method 10133.
EPA method 180.1 and Standard Method 2130B are both nephelometric
methods and are based upon a comparison of the intensity of light
scattered by the sample under defined conditions with the intensity of
light scattered by a standard reference suspension. Great Lakes
Instruments Method 2 is a modulated four beam infrared method using a
ratiometric algorithm to calculate the turbidity value from the four
readings that are produced. Hach Filter Trak (Method 10133) is a laser-
based nephelometric method used to determine the turbidity of finished
drinking waters.
Turbidimeters
Systems are required to use turbidimeters described in EPA-approved
methods for measuring turbidity. For regulatory reporting purposes,
either an on-line or a bench top turbidimeter can be used. If a system
chooses to use on-line units for monitoring, the system must validate
the continuous measurements for accuracy on a regular basis using a
protocol approved by the State.
b. How was this proposal developed? EPA believes the currently
approved methods for analysis of turbidity in drinking water are
appropriate for turbidity analyses that will be conducted under the
LT2ESWTR.
c. Request for comment. EPA requests comment on whether the
turbidity methods proposed today for the LT2ESWTR should be approved,
and whether there are additional methods not proposed that should be
approved.

[[Page 47735]]

L. Laboratory Approval

Given the potentially significant implications in terms of both
cost and public health protection of microbial monitoring under the
LT2ESWTR, laboratory analyses for Cryptosporidium, E. coli, and
turbidity must be accurate and reliable within the limits of approved
methods. Therefore, EPA proposes to require public water systems to use
laboratories that have been approved to conduct analyses for these
parameters by EPA or the State. The following criteria are proposed for
laboratory approval under the LT2ESWTR:
? For Cryptosporidium analyses under the LT2ESWTR, EPA
proposes to approve laboratories that have passed a quality assurance
evaluation under EPA's Laboratory Quality Assurance Evaluation Program
(Lab QA Program) for Analysis of Cryptosporidium in Water (described in
67 FR 9731, March 4, 2002) (USEPA 2002c). If States adopt an equivalent
approval process under State laboratory certification programs, then
systems can use laboratories approved by the State.
? For E. coli analyses, EPA proposes to approve laboratories
that have been certified by EPA, the National Environmental Laboratory
Accreditation Conference, or the State for total coliform or fecal
coliform analysis in source water under 40 CFR 141.74. The laboratory
must use the same analytical technique for E. coli that the laboratory
uses for total coliform or fecal coliform analysis under 40 CFR 141.74.
? Turbidity analyses must be conducted by a person approved
by the State for analysis of turbidity in drinking water under 40 CFR
141.74.
These criteria are further described in the following paragraphs.
1. Cryptosporidium Laboratory Approval
Because States do not currently approve laboratories for
Cryptosporidium analyses and LT2ESWTR monitoring will begin 6 months
after rule promulgation, EPA will initially assume responsibility for
Cryptosporidium laboratory approval. EPA expects, however, that States
will include Cryptosporidium analysis in their State laboratory
certification programs in the future. EPA has established the Lab QA
Program for Cryptosporidium analysis to identify laboratories that can
meet LT2ESWTR data quality objectives. This is a voluntary program open
to laboratories involved in analyzing Cryptosporidium in water. Under
this program, EPA assesses the ability of laboratories to reliably
measure Cryptosporidium occurrence with EPA Methods 1622 and 1623,
using both performance testing samples and an on-site evaluation.
EPA initiated the Lab QA Program for Cryptosporidium analysis prior
to promulgation of the LT2ESWTR to ensure that adequate sample analysis
capacity will be available at qualified laboratories to support the
required monitoring. The Agency is monitoring sample analysis capacity
at approved laboratories through the Lab QA Program, and does not plan
to implement LT2ESWTR monitoring until the Agency determines that there
is adequate laboratory capacity. In addition, utilities that choose to
conduct Cryptosporidium monitoring prior to LT2ESWTR promulgation with
the intent of grandfathering the data may elect to use laboratories
that have passed the EPA quality assurance evaluation.
Laboratories seeking to participate in the EPA Lab QA Program for
Cryptosporidium analysis must submit an interest application to EPA,
successfully analyze a set of initial performance testing samples, and
undergo an on-site evaluation. The on-site evaluation includes two
separate but concurrent assessments: (1) Assessment of the laboratory's
sample processing and analysis procedures, including microscopic
examination, and (2) evaluation of the laboratory's personnel
qualifications, quality assurance/quality control program, equipment,
and recordkeeping procedures.
Laboratories that pass the quality assurance evaluation will be
eligible for approval for Cryptosporidium analysis under the LT2ESWTR.
The Lab QA Program is described in detail in a Federal Register Notice
(67 FR 9731, March 4, 2002) (USEPA 2002c) and additional information
can be found online at: www.epa.gov/safewater/lt2/cla_int.html.
Laboratories in the Lab QA Program will receive a set of three
ongoing proficiency testing (OPT) samples approximately every four
months. EPA will evaluate the precision and recovery data for OPT
samples to determine if the laboratory continues to meet the
performance criteria of the Laboratory QA Program.
2. E. coli Laboratory Approval
Pubic water systems are required to have samples analyzed for E.
coli by laboratories certified under the State drinking water
certification program to perform total coliform and fecal coliform
analyses under 40 CFR 141.74. EPA is proposing that the general
analytical techniques the laboratory is certified to use under the
drinking water certification program (e.g., membrane filtration,
multiple-well, multiple-tube) will be the methods the laboratory can
use to conduct E. coli source water analyses under the LT2ESWTR.
3. Turbidity Analyst Approval
Measurements of turbidity must be conducted by a party approved by
the State. This is consistent with current requirements for turbidity
measurements in drinking water (40 CFR 141.74).
4. Request for Comment
EPA requests comment on the laboratory approval requirements
proposed today, including the following specific issues:
Analyst Experience Criteria
The Lab QA Program, which EPA will use to approve laboratories for
Cryptosporidium analyses under the LT2ESWTR, includes criteria for
analyst experience. Principal analyst/supervisors (minimum of one per
laboratory) should have a minimum of one year of continuous bench
experience with Cryptosporidium and immunofluorescent assay (IFA)
microscopy, a minimum of six months experience using EPA Method 1622
and/or 1623, and a minimum of 100 samples analyzed using EPA Method
1622 and/or 1623 (minimum 50 samples if the person was an analyst
approved to conduct analysis for the Information Collection Rule
Protozoan Method) for the specific analytical procedure they will be
using.
Under the Lab QA Program, other analysts (no minimum number of
analysts per laboratory) should have a minimum of six months of
continuous bench experience with Cryptosporidium and IFA microscopy, a
minimum of three months experience using EPA Method 1622 and/or 1623,
and a minimum of 50 samples analyzed using EPA Method 1622 and/or 1623
(minimum 25 samples if the person was an analyst approved to conduct
analysis for the Information Collection Rule Protozoan Method) for the
specific analytical procedures they will be using.
The Lab QA Program criteria for principal analyst/supervisor
experience are more rigorous than those in Methods 1622 and 1623, which
are as follows: the analyst must have at least 2 years of college
lecture and laboratory course work in microbiology or a closely related
field. The analyst also must have at least 6 months of continuous bench
experience with environmental protozoa detection techniques and IFA

[[Page 47736]]

microscopy, and must have successfully analyzed at least 50 water and/
or wastewater samples for Cryptosporidium. Six months of additional
experience in the above areas may be substituted for two years of
college.
In seeking approval for an Information Collection Request, EPA
requested comment on the Lab QA Program (67 FR 9731, March 4, 2002)
(USEPA 2002c). A number of commenters stated that the analyst
qualification criteria are restrictive and could make it difficult for
laboratories to maintain adequate analyst staffing (and, hence, sample
analysis capacity) in the event of staff turnover or competing
priorities. Some commenters suggested that laboratories and analysts
should be evaluated based on proficiency testing, and that analyst
experience standards should be reduced or eliminated. (Comments are
available in Office of Water docket, number W-01-17).
Another aspect of the analyst experience criteria is that systems
may generate Cryptosporidium data for grandfathering under the LT2ESWTR
using laboratories that meet the analyst experience requirement of
Methods 1622 or 1623 but not the more rigorous principal analyst/
supervisor experience requirement of the Lab QA Program.
EPA requests comment on whether the criteria for analyst experience
in the Lab QA Program are necessary, whether systems are experiencing
difficulty in finding laboratories that have passed the Lab QA Program
to conduct Cryptosporidium analysis, and whether any of the Lab QA
Program criteria should be revised to improve the LT2ESWTR lab approval
process.
State Programs To Approve Laboratories for Cryptosporidium Analysis
Under today's proposal, systems must have Cryptosporidium samples
analyzed by a laboratory approved under EPA's Lab QA Program, or an
equivalent State laboratory approval program. Because States do not
currently approve laboratories for Cryptosporidium analyses, EPA will
initially assume responsibility for Cryptosporidium laboratory
approval. EPA expects, however, that States will adopt equivalent
approval programs for Cryptosporidium analysis under State laboratory
certification programs. EPA requests comment on how to establish that a
State approval program for Cryptosporidium analysis is equivalent to
the Lab QA Program.
Specifically, should EPA evaluate State Approval programs to
determine if they are equivalent to the Lab QA Program? EPA also
requests comment on the elements that would constitute an equivalent
State approval program for Cryptosporidium analyses, including the
following: (1) Successful analysis of initial and ongoing blind
proficiency testing samples prepared using flow cytometry, including a
matrix and meeting EPA's pass/fail criteria (described in USEPA 2002c);
(2) an on-site evaluation of the laboratory's sample processing and
analysis procedures, including microscopic examination skills, by
auditors who meet the qualifications of a principal analyst as set
forth in the Lab QA Program (described in USEPA 2002c); (3) an on-site
evaluation of the laboratory's personnel qualifications, quality
assurance/quality control program, equipment, and recordkeeping
procedures; (4) a data audit of the laboratories' QC data and
monitoring data; and (5) use of the audit checklist used in the Lab QA
Program or equivalent.

M. Requirements for Sanitary Surveys Conducted by EPA

1. Overview
In today's proposal, EPA is requesting comment on establishing
requirements for public water systems with significant deficiencies as
identified in a sanitary survey conducted by EPA under SDWA section
1445. These requirements would apply to surface water systems for which
EPA is responsible for directly implementing national primary drinking
water regulations (i.e., systems not regulated by States with primacy).
As described in this section, these requirements would ensure that
systems in non-primacy States, currently Wyoming, and systems not
regulated by States, such as Tribal systems, are subject to standards
for sanitary surveys similar to those that apply to systems regulated
by States with primacy.
2. Background
As established by the IESWTR in 40 CFR 142.16(b)(3), primacy States
must conduct sanitary surveys for all surface water systems no less
frequently than every three years for community water systems and no
less frequently than every five years for noncommunity water systems.
The sanitary survey is an onsite review and must address the following
eight components: (1) Source, (2) treatment, (3) distribution system,
(4) finished water storage, (5) pumps, pump facilities, and controls,
(6) monitoring, reporting, and data verification, (7) system management
and operation, and (8) operator compliance with State requirements.
Under the IESWTR, primacy States are required to have the
appropriate rules or other authority to assure that systems respond in
writing to significant deficiencies outlined in sanitary survey reports
no later than 45 days after receipt of the report, indicating how and
on what schedule the system will address significant deficiencies noted
in the survey (40 CFR 142.16(b)(1)(ii)). Further, primacy States must
have the authority to assure that systems take necessary steps to
address significant deficiencies identified in sanitary survey reports
if such deficiencies are within the control of the system and its
governing body (40 CFR 142.16(b)(1)(iii)). The IESWTR did not define a
significant deficiency, but required that primacy States describe in
their primacy applications how they will decide whether a deficiency
identified during a sanitary survey is significant for the purposes of
the requirements stated in this paragraph (40 CFR 142.16(b)(3)(v)).
EPA conducts sanitary surveys under SDWA section 1445 for public
water systems not regulated by primacy States (e.g., Tribal systems,
Wyoming). However, EPA does not have the authority required of primacy
States under 40 CFR 142 to ensure that systems address significant
deficiencies identified during sanitary surveys. Consequently, the
sanitary survey requirements established by the IESWTR create an
unequal standard. Systems regulated by primacy States are subject to
the States' authority to require correction of significant deficiencies
noted in sanitary survey reports, while systems for which EPA has
direct implementation authority do not have to meet an equivalent
requirement.
3. Request for Comment
In order to ensure that systems for which EPA has direct
implementation authority address significant deficiencies identified
during sanitary surveys, EPA requests comment on establishing either or
both of the following requirements under 40 CFR 141 as part of the
NPDWR established in the final LT2ESWTR:

(1) For sanitary surveys conducted by EPA under SDWA section
1445, systems would be required to respond in writing to significant
deficiencies outlined in sanitary survey reports no later than 45
days after receipt of the report, indicating how and on what
schedule the system will address significant deficiencies noted in
the survey.
(2) Systems would be required to correct significant
deficiencies identified in sanitary survey reports if such
deficiencies are within the control of the system and its governing
body.

[[Page 47737]]

For the purposes of these requirements, a sanitary survey, as
conducted by EPA, is an onsite review of the water source (identifying
sources of contamination by using results of source water assessments
where available), facilities, equipment, operation, maintenance, and
monitoring compliance of a public water system to evaluate the adequacy
of the system, its sources and operations, and the distribution of safe
drinking water. A significant deficiency includes a defect in design,
operation, or maintenance, or a failure or malfunction of the sources,
treatment, storage, or distribution system that EPA determines to be
causing, or has the potential for causing the introduction of
contamination into the water delivered to consumers.

V. State Implementation

This section describes the regulations and other procedures and
policies States will be required to adopt to implement the LT2ESWTR, if
finalized as proposed today. States must continue to meet all other
conditions of primacy in 40 CFR Part 142.
The Safe Drinking Water Act (Act) establishes requirements that a
State or eligible Indian tribe must meet to assume and maintain primary
enforcement responsibility (primacy) for its public water systems.
These requirements include: (1) Adopting drinking water regulations
that are no less stringent than Federal drinking water regulations, (2)
adopting and implementing adequate procedures for enforcement, (3)
keeping records and making reports available on activities that EPA
requires by regulation, (4) issuing variances and exemptions (if
allowed by the State), under conditions no less stringent than allowed
under the Act, and (5) adopting and being capable of implementing an
adequate plan for the provisions of safe drinking water under emergency
situations.
40 CFR part 142 sets out the specific program implementation
requirements for States to obtain primacy for the public water supply
supervision program as authorized under section 1413 of the Act. In
addition to adopting basic primacy requirements specified in 40 CFR
Part 142, States may be required to adopt special primacy provisions
pertaining to specific regulations where implementation of the rule
involves activities beyond general primacy provisions. States must
include these regulation specific provisions in an application for
approval of their program revision. Primacy requirements for today's
proposal are discussed below.
To implement the proposed LT2ESWTR, States will be required to
adopt revisions to:
Sec. 141.2--Definitions
Sec. 141.71--Criteria for avoiding filtration
Sec. 141.153--Content of the reports
Sec. 141.170--Enhanced filtration and disinfection
Subpart Q--Public Notification
New Subpart W--Additional treatment technique requirements for
Cryptosporidium
Sec. 142.14--Records kept by States
Sec. 142.15--Reports by States
Sec. 142.16--Special primacy requirements

A. Special State Primacy Requirements

To ensure that a State program includes all the elements necessary
for an effective and enforceable program under today's rule, a State
primacy application must include a description of how the State will
perform the following:
(1) Approve watershed control programs for the 0.5 log watershed
control program credit in the microbial toolbox (see section IV.C.2);
(2) Assess significant changes in the watershed and source water as
part of the sanitary survey process and determine appropriate follow-up
action (see section IV.A);
(3) Determine that a system with an uncovered finished water
storage facility has a risk mitigation plan that is adequate for
purposes of waiving the requirement to cover the storage facility or
treat the effluent (see section IV.E);
(4) Approve protocols for removal credits under the Demonstration
of Performance toolbox option (see section IV.C.17) and for site
specific chlorine dioxide and ozone CT tables (see section IV.C.14);
and
(5) Approve laboratories to analyze for Cryptosporidium.
Note that a State program can be more, but not less, stringent than
Federal regulations. As such, some of the elements listed here may not
be applicable to a specific State program. For example, if a State
chooses to require all finished water storage facilities to be covered
or provide treatment and not to allow a risk mitigation plan to
substitute for this requirement, then the description for item (3)
would be inapplicable.

B. State Recordkeeping Requirements

The current regulations in Sec. 142.14 require States with primacy
to keep various records, including the following: Analytical results to
determine compliance with MCLs, MRDLs, and treatment technique
requirements; system inventories; State approvals; enforcement actions;
and the issuance of variances and exemptions. The proposed LT2ESWTR
will require States to keep additional records of the following,
including all supporting information and an explanation of the
technical basis for each decision:
? Results of source water E. coli and Cryptosporidium
monitoring;
? Cryptosporidium bin classification for each filtered
system, including any changes to initial bin classification based on
review of the watershed during sanitary surveys or the second round of
monitoring;
? Determination of whether each unfiltered system has a mean
source water Cryptosporidium level above 0.01 oocysts/L;
? The treatment processes or control measures that each
system employs to meet Cryptosporidium treatment requirements under the
LT2ESWTR; this includes documentation to demonstrate compliance with
required design and implementation criteria for receiving credit for
microbial toolbox options, as specified in section IV.C;
? A list of systems required to cover or treat the effluent
of an uncovered finished water storage facilities; and
? A list of systems for which the State has waived the
requirement to cover or treat the effluent of an uncovered finished
water storage facility, along with supporting documentation of the risk
mitigation plan.

C. State Reporting Requirements

EPA currently requires in Sec. 142.15 that States report to EPA
information such as violations, variance and exemption status, and
enforcement actions. The LT2ESWTR, as proposed, will add additional
reporting requirements in the following area:
? The Cryptosporidium bin classification for each filtered
system, including any changes to initial bin classification based on
review of the watershed during sanitary surveys or the second round of
monitoring;
? The determination of whether each unfiltered system has a
mean source water Cryptosporidium level above 0.01 oocysts/L, including
any changes to this determination based on the second round of
monitoring.

D. Interim Primacy

On April 28, 1998, EPA amended its State primacy regulations at 40
CFR 142.12 to incorporate the new process identified in the 1996 SDWA
Amendments for granting primary enforcement authority to States while
their applications to modify their primacy programs are under review
(63 FR 23362, April 28, 1998) (USEPA 1998f). The new process grants
interim

[[Page 47738]]

primary enforcement authority for a new or revised regulation during
the period in which EPA is making a determination with regard to
primacy for that new or revised regulation. This interim enforcement
authority begins on the date of the primacy application submission or
the effective date of the new or revised State regulation, whichever is
later, and ends when EPA makes a final determination. However, this
interim primacy authority is only available to a State that has primacy
(including interim primacy) for every existing NPDWR in effect when the
new regulation is promulgated.
As a result, States that have primacy for every existing NPDWR
already in effect may obtain interim primacy for this rule, beginning
on the date that the State submits the application for this rule to
USEPA, or the effective date of its revised regulations, whichever is
later. In addition, a State that wishes to obtain interim primacy for
future NPDWRs must obtain primacy for this rule. As described in
Section IV.A, EPA expects to oversee the initial source water
monitoring that will be conducted under the LT2ESWTR by systems serving
at least 10,000 people, beginning 6 months following rule promulgation.

VI. Economic Analysis

This section summarizes the economic analysis (EA) for the LT2ESWTR
proposal. The EA is an assessment of the benefits, both health and non-
health related, and costs to the regulated community of the proposed
regulation, along with those of regulatory alternatives that the Agency
considered. EPA developed this EA to meet the requirement of SDWA
section 1412(b)(3)(C) for a Health Risk Reduction and Cost Analysis
(HRRCA), as well as the requirements of Executive Order 12866,
Regulatory Planning and Review, under which EPA must estimate the costs
and benefits of the LT2ESWTR. The full EA is presented in Economic
Analysis for the Long Term 2 Enhanced Surface Water Treatment Rule
(USEPA 2003a), which is available in the docket for today's proposal
(www.epa.gov/edocket/).
Today's proposed LT2ESWTR is the second in a staged set of rules
that address public health risks from microbial contamination of
surface and GWUDI drinking water supplies and, more specifically,
prevent Cryptosporidium from reaching consumers. As described in
section I, the Agency promulgated the IESWTR and LT1ESWTR to provide a
baseline of protection against Cryptosporidium in large and small
drinking water systems, respectively. Today's proposed rule would
achieve further reductions in Cryptosporidium exposure for systems with
the highest vulnerability. This economic analysis considers only the
incremental reduction in exposure from the two previously promulgated
rules (IESWTR and LT1ESWTR) to the alternatives evaluated for the
LT2ESWTR.
Both benefits and costs are determined as annualized present
values. The process allows comparison of cost and benefit streams that
are variable over a given time period. The time frame used for both
benefit and cost comparisons is 25 years; approximately five years
account for rule implementation and 20 years for the average useful
life of the equipment used to comply with treatment technique
requirements. The Agency uses social discount rates of both three
percent and seven percent to calculate present values from the stream
of benefits and costs and also to annualize the present value estimates
(see EPA's Guidelines for Preparing Economic Analyses (USEPA 2000c) for
a discussion of social discount rates). The LT2ESWTR EA (USEPA 2003a)
also shows the undiscounted stream of both benefits and costs over the
25 year time frame.

A. What Regulatory Alternatives Did the Agency Consider?

Regulatory alternatives considered by Agency for the LT2ESWTR were
developed through the deliberations of the Stage 2 M-DBP Federal
Advisory Committee (described in section II). The Committee considered
several general approaches for reducing the risk from Cryptosporidium
in drinking water. As discussed in section IV.A.2, these approaches
included both additional treatment requirements for all systems and
risk-targeted treatment requirements for systems with the highest
vulnerability to Cryptosporidium following implementation of the IESWTR
and LT1ESWTR. In addition, the Committee considered related factors
such as surrogates for Cryptosporidium monitoring and alternative
monitoring strategies to minimize costs to small drinking water
systems.
After considering these general approaches, the Committee focused
on four specific regulatory alternatives for filtered systems (see
Table VI-1). With the exception of Alternative 1, which requires all
systems to achieve an additional 2 log (99%) reduction in
Cryptosporidium levels, these alternatives incorporate a microbial
framework approach. In this approach, systems are classified in
different risk bins based on the results of source water monitoring.
Additional treatment requirements are directly linked to the risk bin
classification. Accordingly, these rule alternatives are differentiated
by two criteria: (1) The Cryptosporidium concentrations that define the
bin boundaries and (2) the degree of treatment required for each bin.
In assessing regulatory alternatives, EPA and the Advisory
Committee were concerned with the following questions: (1) Do the
treatment requirements adequately control Cryptosporidium
concentrations in finished water? (2) How many systems will be required
to add treatment? (3) What is the likelihood that systems with high
source water Cryptosporidium concentrations will not be required to
provide additional treatment (i.e., be misclassified in a low risk
bin)? and (4) What is the likelihood that systems with low source water
Cryptosporidium concentrations will be required to provide unnecessary
additional treatment (i.e., misclassified in a high risk bin)?
The Committee reached consensus regarding additional treatment
requirements for unfiltered systems and uncovered finished water
storage facilities without formally identifying regulatory
alternatives. Table VI-1 summarizes the four alternatives that were
considered for filtered systems.

[[Continued on page 47739]]

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