|TOC (mg/l)||0 - <60||60 - <120||=>120|
|2 - 4||35||25||15|
|4 - 8||45||35||25|
2.3 Microbial Benchmarking/Profiling
A microbial benchmark to provide a methodology and process by which a PWS and the State, working together, assure that there will be no significant reduction in microbial protection as the result of modifying disinfection practices in order to meet MCLs for TTHM and HAA5 should be established as follows:
A. Applicability. The following PWSs to which the IESWTR applies must prepare a disinfection profile:
1) PWSs with measured TTHM levels of at least 80% of the MCL (0.064 mg/l) as an annual average for the most recent 12 month compliance period for which compliance data are available prior to November 1998 (or some other period designated by the State),
2) PWSs with measured HAA5 levels of at least 80% of the MCL (0.048 mg/l) as an annual average for the most recent 12 month period for which data are available (or some other period designated by the State) - In connection with HAA5 monitoring, the following provisions apply:
a) PWSs that have collected HAA5 data under the Information Collection Rule must use those data to determine the HAA5 level, unless the State determines that there is a more representative annual data set.
b) For those PWSs that do not have four quarters of HAA5 data 90 days following the IESWTR promulgation date, HAA5 monitoring must be conducted for four quarters.
B. Disinfection profile. A disinfection profile consists of a compilation of daily Giardia lamblia log inactivations (or virus inactivations under conditions to be specified), computed over the period of a year, based on daily measurements of operational data (disinfectant residual concentration(s), contact time(s), temperature(s), and where necessary, pH(s)). The PWS will then determine the lowest average month (critical period) for each 12 month period and average critical periods to create a "benchmark" reflecting the lower bound of a PWS's current disinfection practice. Those PWSs that have all necessary data to determine profiles, using operational data collected prior to promulgation of the IESWTR, may use up to three years of operational data in developing those profiles. Those PWSs that do not have three years of operational data to develop profiles must conduct the necessary monitoring to develop the profile for one year beginning no later than 15 months after promulgation, and use up to two years of existing operational data to develop profiles.
C. State review. The State will review disinfection profiles as part of its sanitary survey. Those PWSs required to develop a disinfection profile that subsequently decide to make a significant change in disinfection practice (i.e., move point of disinfection, change the type of disinfectant, change the disinfection process, or any other change designated as significant by the State) must consult with the State prior to implementing such a change. Supporting materials for such consultation must include a description of the proposed change, the disinfection profile, and an analysis of how the proposed change will affect the current disinfection.
D. Guidance. EPA, in consultation with interested stakeholders, will develop detailed guidance for States and PWSs on how to develop and evaluate disinfection profiles, identify and evaluate significant changes in disinfection practices, and guidance on moving the point of disinfection from prior to the point of coagulant addition to after the point of coagulant addition.
2.4 Disinfection Credit
Consistent with the existing provisions of the 1989 Surface Water Treatment Rule, credit for compliance with applicable disinfection requirements should continue to be allowed for disinfection applied at any point prior to the first customer. EPA will develop guidance on the use and costs of oxidants that control water quality problems (e.g., zebra mussels, Asiatic clams, iron, manganese, algae) and whose use will reduce or eliminate the formation of DBPs of public health concern.
Turbidity Performance Requirements. For all surface water systems that use conventional treatment or direct filtration, serve more than 10,000 people, and are required to filter: a) the turbidity level of a system's combined filtered water at each plant must be less than or equal to 0.3 NTU in at least 95 percent of the measurements taken each month and, b) the turbidity level of a system's combined filtered water at each plant must at no time exceed 1 NTU. For both the maximum and the 95th percentile requirements. compliance shall be determined based on measurements of the combined filter effluent at four-hour intervals.
Individual Filter Requirements. All surface water systems that use rapid granular filtration, serve more than l0,000 people, and are required to filter shall conduct continuous monitoring of turbidity for each individual filter and shall provide an exceptions report to the State on a monthly basis. Exceptions reporting shall include the following: 1) any individual filter with a turbidity level greater than l.0 NTU based on 2 consecutive measurements fifteen minutes apart; and 2) any individual filter with a turbidity level greater than 0.5 NTU at the end of the first 4 hours of filter operation based on 2 consecutive measurements fifteen minutes apart. A filter profile will be produced if no obvious reason for the abnormal filter performance can be identified.
If an individual filter has turbidity levels greater than l .0 NTU based on 2 consecutive measurements fifteen minutes apart at any time in each of 3 consecutive months, the system shall conduct a self-assessment of the filter utilizing as guidance relevant portions of guidance issued by the Environmental Protection Agency for Comprehensive Performance Evaluation (CPE). If an individual filter has turbidity levels greater than 2.0 NTU based on 2 consecutive measurements fifteen minutes apart at any time in each of two consecutive months, the system will arrange for the conduct of a CPE by the State or a third party approved by the State.
State Authority. States must have rules or other authority to require systems to conduct a Composite Correction Program (CCP) and to assure that systems implement any follow-up recommendations that result as part of the CCP.
2.6 Cryptosporidium MCLG
EPA should establish an MCLG to protect public health. The Agency should describe existing and ongoing research and areas of scientific uncertainty on the question of which species of Cryptosporidium represents a concern for public health (e.g. parvum, muris, serpententious) and request further comment on whether to establish an MCLG on the genus or species level.
In the event the Agency establishes an MCLG on the genus level, EPA should make clear that the objective of this MCLG is to protect public health and explain the nature of scientific uncertainty on the issue of taxonomy and cross reactivity between strains. The Agency should indicate that the scope of MCLG may change as scientific data on specific strains of particular concern to human health become available.
2.7 Removal of Cryptosporidium
All surface water systems that serve more than l 0,000 people and are required to filter must achieve at least a 2 log removal of Cryptosporidium. Systems which use rapid granular filtration (direct filtration or conventional filtration treatment - as currently defined in the SWTR), and meet the turbidity requirements described in Section 2.5 are assumed to achieve at least a 2 log removal of Cryptosporidium. Systems which use slow sand filtration and diatomaceous earth filtration and meet existing turbidity performance requirements (less than 1 NTU for the 95th percentile or alternative criteria as approved by the State) are assumed to achieve at least a 2 log removal of Cryptosporidium.
Systems may demonstrate that they achieve higher levels of physical removal.
2.8 Multiple Barrier Concept
EPA should issue a risk-based proposal of the Final Enhanced Surface Water Treatment Rule for Cryptosporidium embodying the multiple barrier approach (e.g. source water protection, physical removal, inactivation, etc.), including, where risks suggest appropriate, inactivation requirements. In establishing the Final Enhanced Surface Water Treatment Rule, the following issues will be evaluated:
2. 9 Sanitary Surveys
Sanitary surveys operate as an important preventive tool to identify water system deficiencies that could pose a risk to public health. EPA and ASDWA have issued a joint guidance dated 12/21/95 on the key components of an effective sanitary survey. The following provisions concerning sanitary surveys should be included.
A) A sanitary survey is an onsite review of the water source (identifying sources of contamination 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.
B) Components of a sanitary survey may be completed as part of a staged or phased state review process within the established frequency interval set forth below.
C) A sanitary survey must address each of the eight elements outlined in the December 1995 EPA/STATE Guidance on Sanitary Surveys.
A) Conduct sanitary surveys for all surface water systems (including groundwater under the influence) no less frequently than every three years for community systems except as provided below and no less frequently than every five years for noncommunity systems.
- May "grandfather"sanitary surveys conducted after December 1995, if they address the eight sanitary survey components outlined above.
B) For community systems determined by the State to have outstanding performance based on prior sanitary surveys, successive sanitary surveys may be conducted no less than every five years.
III. FOLLOW UP
A) Systems must respond to deficiencies outlined in a sanitary survey report within at least 45 days, indicating how and on what schedule the system will address significant deficiencies noted in the survey.
B) States must have the appropriate rules or other authority to assure that facilities take the steps necessary to address significant deficiencies identified in the survey report that are within the control of the PWS and its governing body.
Agreed to by:
Peter L. Cook, National Association of Water Companies
Michael A. Dimitriou, International Ozone Association
Cynthia C. Dougherty, US Environmental Protection Agency
Mary J.R. Gilchrist, American Public Health Association
Jeffrey K. Griffiths, National Association of People with AIDS
Barker Hamill, Association of State Drinking Water Administrators
Robert H. Harris, Environmental Defense Fund
Edward G. Means III, American Water Works Association
Rosemary Menard, Large Unfiltered Systems
Erik D. Olson, Natural Resources Defense Council
Brian L. Ramaley, Association of Metropolitan Water Agencies
Charles R. Reading Jr., Water and Wastewater Equipment Manufacturers Association
Suzanne Rude, National Association of Regulatory Utility Commissioners
Ralph Runge, Chlorine Chemistry Council
Coretta Simmons, National Association of State Utility Consumer Advocates Bruce Tobey, National League of Cities
Chris J. Wiant, National Association of City and County Health Officials; National Environmental Health Association