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NPDES Permits in New England

OMSAP  LogoOutfall Monitoring Science Advisory Panel (OMSAP) Meeting

Monday, March 22, 1999 10:00 AM - 2:00 PM
MADEP Boston
FINAL MINUTES

ATTENDANCE

Members Present: Andy Solow, WHOI (chair); Robert Beardsley, WHOI; Robert Chen, UMB; Robert Kenney, URI; Judy Pederson, MIT/Sea Grant; Bill Robinson, UMB; and Jim Shine, Harvard School of Public Health.

Observers: Grace Bigornia-Vitale, MWRA; Elizabeth Bruce, Battelle; Cathy Coniaris, OMSAP Assistant; Kelly Coughlin, MWRA; Patty Daley, Cape Cod Commission; Mike Delaney, MWRA; Cate Doherty, Save the Harbor/Save the Bay; Marianne Farrington, New England Aquarium; Pamela Harvey, MADEP; Carlton Hunt, Battelle; Russell Isaac, MADEP; Ken Keay, MWRA; Kristyn Lemieux, ENSR; Matt Liebman, EPA; Steve Lipman, MADEP; Ron Manfredonia, EPA; Mike Mickelson, MWRA; Arleen O'Donnell, MADEP; Cornelia Potter, MWRA Advisory Board; Susan Redlich, WAC; Virginia Renick, MWRA; Andrea Rex, MWRA; Jack Schwartz, MADMF; Dave Taylor, MWRA; Dave Tomey, EPA; and Heather Trulli, Battelle.

Summary prepared by C. Coniaris. Post-meeting comments are included in [brackets]. All such comments have been inserted for clarification only. They do not, nor are they intended to, suggest that such insertions were part of the live meeting components and have been expressly set-off so as to avoid such inference.

SUMMARY OF ACTION ITEMS & RECOMMENDATIONS

  1. OMSAP agreed to review the upcoming report on Bays Eutrophication Model runs for 1993 and 1994. The Panel will also contact the original Model Evaluation Group (MEG) as well as additional scientists to request that they review the report. A MEG may be convened this summer with B. Beardsley as chair.
  2. OMSAP agreed to host a public monitoring workshop this summer. MWRA will develop a proposed agenda for OMSAP/PIAC/IAAC review. A subcommittee will meet to plan for this workshop. Suggestions for meeting format and content are welcome and should be sent to: cconiaris@neiwpcc.org.
  3. OMSAP will review the hypotheses in the Outfall Monitoring Plan phase 1 to see if the current monitoring program is addressing them.
  4. OMSAP postponed decision on the draft food web model scope of work presented by the MWRA at the December 18, 1998 OMSAP meeting pending additional information from the Cape Cod Commission by April 23, 1999. [Update: the CCC has postponed this date.]

FINAL MINUTES

December 18, 1998 OMSAP minutes were approved as amended.

REVIEW OF DRAFT OMSAP/PIAC/IAAC PROTOCOL
Comments to the draft protocol should be sent to C. Coniaris. The group had a brief discussion regarding meeting scheduling of the three groups. C. Doherty pointed out that the PIAC has requested that the OMSAP not vote on an issue until the PIAC has had a chance to discuss it. She said one suggestion was to have PIAC meet right after OMSAP and then meet once again before the next OMSAP meeting. OMSAP/PIAC/IAAC may eventually decide to meet on the same day. OMSAP would meet in the morning and PIAC and IAAC would meet separately in the afternoon to discuss OMSAP's proceedings as well as other issues.

REPORT FROM THE PUBLIC INTEREST ADVISORY COMMITTEE
C. Doherty summarized the proceedings of the second PIAC meeting held on March 2, 1999 [minutes available]. It was decided to keep the membership open for the next two PIAC meetings with the understanding that the PIAC will not allow membership to get so large that the group becomes inefficient. They approved new membership: Anthony Chatwin from the Conservation Law Foundation and Mary Loebig from Stop the Outfall Pipe. PIAC also discussed the MWRA Water Works and Sewerage lab consolidation. MWRA assured PIAC that the consolidation of the labs would not affect the communication of monitoring results from the Harbor Studies and NPDES departments. The PIAC accepted the assurance that this would not become an issue of concern but would like to be kept informed of any new developments on this issue. PIAC decided to request that OMSAP postpone any decisions regarding the draft food web model scope of work presented by the MWRA at the December 18, 1998 OMSAP meeting pending further information from the Cape Cod Commission. The PIAC reviewed and commented on the draft protocol. PIAC agreed that if an individual organization has a concern, they should first discuss it with PIAC so that the entire group can learn about it and potentially form a collective opinion. Finally, there were two informational presentations on plume tracking and endocrine disrupters.

REPORT FROM THE INTER-AGENCY ADVISORY COMMITTEE M. Liebman summarized the proceedings of the first IAAC meeting held on February 24, 1999 [minutes available]. The group discussed the draft protocol and decided to form a subcommittee consisting of Sal Testaverde, Leigh Bridges and Matt Liebman to discuss the mission of the group, protocol, OMSAP charter, as well as the Cape Cod Commission's request to leave PIAC and join the IAAC. At the IAAC meeting, M. Liebman gave an informational presentation on endocrine disrupters and EDSTAC (Endocrine Disruptor Screening and Testing Advisory Committee). EDSTAC is a committee with members from EPA, other agencies, and industries and its purpose is to develop a process to screen the ~87,000 potential endocrine disruptors. IAAC then briefly discussed PCBs and elected S. Testaverde as chair of IAAC.

PLUME TRACKING M. Mickelson presented the draft plume tracking design. The outfall is scheduled to go on-line around September 1999 and MWRA is planning for a plume tracking survey this December. The draft NPDES permit requires plume tracking since it will measure dilution which is used in calculating effluent limits. Details are in appendix N of the draft permit. The draft permit requires:

  • Acoustical technology: MWRA will utilize John Proni's acoustic tracking technique as well as an Acoustic Doppler Current Profiler (ADCP).
  • To understand the dilution available for the discharge.
  • To field test and certify whether the outfall's minimum dilution is equal to, or greater than, the predicted minimum dilution specified by Roberts and Snyder (1993b). This report was provided to OMSAP and is available to others. During lunch, a video of the Roberts and Snyder physical scale model was viewed which showed dye being released from diffuser models under various discharge and current velocities.
  • Completion of study within 180 days of issuance of the permit. MWRA's proposed study design, with surveys in both fall/winter 1999 (unstratified conditions) and early summer 2000 (stratified water column) can be only partially completed within that requirement. MWRA will propose a reasonable timeframe for study completion to EPA/MADEP.

The main goal of the plume tracking study is to measure dilution accurately. A secondary goal is to demonstrate that the diluted plume does not travel intact to resource areas. Flow from the diffuser is a two step process: vertical turbulent motion due to buoyancy and momentum of the discharge followed by much slower horizontal travelling of the diluted plume. Much of the dilution occurs during the vertical mixing step. There are three definitions of dilution but the one preferred by EPA is "flux averaged dilution" where the concentration at any point is weighted by the horizontal velocity. The zone of initial dilution (ZID) is considered to be 60m (the water depth multiplied by two) on either side of the line of diffusers.

M. Mickelson pointed out patterns in the Roberts and Snyder model results. Dilution decreases (i.e. becomes less effective) with higher effluent flow, with strong water stratification, and with slower currents. To examine the effects on dilution with varying combinations of these conditions, Roberts and Snyder developed a model which can calculate dilution. MWRA will run this model using field information (flow, current, and stratification) to test if the same results are obtained in the field as the model. It is expected that flow will vary over the course of the day as well as annually so there will be about 25 hours of dye addition and the study will be repeated in winter and summer.

D. Tomey asked how the Roberts and Snyder model compares to the ULINE model. M. Mickelson replied that Roberts and Snyder consider ULINE obsolete because it considers buoyancy but not momentum, and only simple linear stratification. D. Tomey suggested comparing the Roberts and Snyder model to ULINE since that model was used in the Environmental Impact Statement and outfall-siting studies. B. Beardsley pointed out that ULINE would be more conservative since it does not consider momentum of the flow.

OMSAP members then commented on the study design. B. Chen asked about flow and turbulence and if there is any possibility that the flow is not high enough to mix particles and oil causing higher concentrations to discharge from the first riser. K. Keay replied that the connections of the risers to the outfall tunnel are near the floor of the tunnel to purge trapped salt water, except for the last riser which has a ceiling-connection to purge trapped air. M. Mickelson added that the tunnel has a venturi near the start of the diffuser section to increase turbulent mixing to prevent seawater intrusion through the full length of the tunnel. C. Hunt added that measurements such as total suspended solids and metals will track how well mixed the effluent is.

J. Shine asked about dye smearing in the tunnel. If the effluent is not well mixed, then there will be some parcels of water without dye (but containing particles) and this could possibly overestimate dilution. M. Mickelson pointed out that MWRA is considering adding the dye at the end of the disinfection basin and mixing in the tunnel is good. B. Beardsley added that if the flow is very turbulent, then the dye will travel as a "slug". J. Shine pointed out that one needs to make sure that the concentration of dye in the tunnel is uniform all of the time (i.e. little or no smearing). M. Mickelson stated that the dye will mix and smear but the dye will build up quickly in the tunnel and MWRA will measure smearing. B. Beardsley thinks that there will be a diurnal change in discharge and so he asked if the dye will be added according to flow rates. M. Mickelson replied yes, dye addition will be proportional to effluent flow.

C. Hunt stated that there will be a survey before the plume tracking to sample the apparent dye background. B. Chen asked if the models give a residence time in the ZID. M. Mickelson replied that the rising plume takes about three minutes to reach the ZID and hours to days to for subsequent horizontal mixing. The initial dilution can be from 60:1 to as high as 600:1 in extreme conditions and he expects to see 250:1 in the winter. The permit assumes that the re-entraining (diluted effluent which re-enters the plume) water has a dilution of 364:1. Re-entrained water will be examined by measuring salinity and optical characteristics.

B. Beardsley pointed out that there will be less dilution with rotary tides and asked how this will be measured. M. Mickelson replied that moored USGS current meters describe the water column at two or more different depths, and horizontal velocity of the waste field will be measured using a shipboard Acoustic Doppler Current Profiler (ADCP). He pointed out that concern that the effluent might travel intact without dilution in a layer without any further mixing will be addressed by using John Proni's acoustical techniques for imaging turbulent swirls in the water, salinity differences, and suspended solids. J. Pederson suggested sending the Proni (1996) report to OMSAP. M. Mickelson recalled that the Proni (1996) report showed layers and internal waves. B. Beardsley pointed out that Mass Bay has a lot of internal waves, especially in the summer, which are generated by Stellwagen Bank and it is routine to use acoustics to measure them. He is not sure what is in the effluent which would cause additional scattering with acoustics. It would be interesting to see some of those results. D. Tomey will provide copies of the report to OMSAP. D. Tomey added that acoustics track the backscattering from solids which can show layering but as B. Beardsley pointed out, it is unclear what all of those particles represent. M. Mickelson stated that J. Proni said that acoustics can detect salinity discontinuities (e.g. the Schlieren effect visible when sugar and water are mixed together). Those "little swirly things" echo sound and can be detected more easily than solids for which the load is lower with secondary treatment. D. Tomey added that there are also better sampling techniques available now.

B. Chen asked if the BOSS (Battelle Ocean Sampling System) can sample any lower than 3 m off the bottom. C. Hunt replied that it can sample 2 m off the bottom if the ship is stationary and the towyo can reach 3-5 m off the bottom. Battelle plans to sample as low as possible to see if there is any unusual layering. The USGS mooring 1 km southeast from the outfall has sediment traps. B. Chen added that the 1m-above-bottom sediment trap has captured a layer of flowing particles near the bottom in Mass Bay and that layer could possibly be a significant transport mode. B. Beardsley asked if the number of diffusers is variable in the Roberts and Snyder model. M. Mickelson replied yes. C. Hunt requested that any additional comments on the draft study design be forwarded to MWRA as soon as possible.

[UPDATE: Here is a clarification of the ZID definition provided by Dave Tomey. The permit had a different definition of the mixing zone than the outfall EIR/EIS. The size of the mixing zone for the permit was not determined based on a simple depth factor, as used in the Section 301 (h) definition and implied in the March 1999 OMSAP minutes. The Fact Sheet of the MWRA permit stated: "The draft permit limitations are based on the most restrictive type of mixing zone, the area of hydraulic initial dilution, called the zone of initial dilution. For the draft permit, that area is expected to occur at approximately 60 meters (197 feet) away from the diffuser outfall, and that determination incorporated only the most conservative (i.e., ‘worst case') conditions of the receiving water and discharge flow." (Note: this applies to the final permit as well as the draft). The MWRA Facilities Plan/EIR and the EPA EIS, which predated the permit, assumed a dynamic mixing zone. Both agencies agreed to define the mixing zone as a dynamic edge of hydraulic mixing, which, in reality, would vary with flow and ambient currents. The permit, on the other hand, needed a more definable area for developing a practical compliance strategy. Worst case conditions and the results of Roberts' modeling were used to delineate the permit mixing zone with the dimensions of 52.5 m in any horizontal direction from diffuser axis. (This was expanded to be about 60 m which happens to be about 2 times the depth.)

Although this distinction is not major issue, it is important to clarify the mixing zone in the context of the proposed plume tracking study. The primary objective of the study is to verify the dilution and immediate dispersion of the effluent plume as modeled in the EIR/EIS and subsequent analyses under the conditions present during the study. It will be important to find the dynamic hydraulic mixing zone first to verify the modeled dilution at that point. Then the study will follow the advection of the plume in the farfield to about 500:1 dilution after semi-steady state conditions are achieved. Whether the zone is completely encompassed within the 60 m box is only of secondary concern since the study is only a snapshot of mixing under the particular conditions of flow, ambient current and wind at the time of the study.]

FORMATION OF A MODEL REPORT EVALUATION FOCUS GROUP
The original Model Evaluation Group convened by the Outfall Monitoring Task Force assisted in the development of the Bays Eutrophication Model (BEM) model and reviewed the 1992 model runs. One of the recommendations from the group was for MWRA to run the model for 1993 (large phytoplankton bloom) and 1994 (lowest nearfield DO in the bottom waters on record for the baseline period) to see how well the model captures those features. MWRA suggested that OMSAP form a model evaluation focus group to evaluate these model runs. J. Pederson added that the outside review helped the model become more efficient and understandable. K. Keay stated that a draft of the report will be ready in the next 6-8 weeks. B. Beardsley said based on that time frame, he thinks the group could complete the review by July or August 1999.

J. Pederson suggested that the issue of model ownership be addressed by the group. A home for the model needs to be found so that it can be maintained, updated, and used for other outfalls. MIT and U Mass have showed interest in the past if additional state/federal support was made available.

ACTION: OMSAP agreed to review the upcoming report on Bays Eutrophication Model runs for 1993 and 1994. The Panel will also contact the original Model Evaluation Group (MEG) as well as additional scientists to request that they review the report. A MEG may be convened this summer with B. Beardsley as chair.

1999 OMSAP MONITORING WORKSHOP
The OMSAP charter states that the OMSAP shall have a public meeting once a year "to explain findings, to explain their significance and to hear and respond to concerns from the public". MWRA is willing to support this effort by presenting monitoring results. C. Doherty requested that the Public Interest Advisory Committee be involved in the planning. She hopes that a user-friendly document comes out of the meeting. OMSAP agreed to host a public monitoring workshop this summer.

The group then had a discussion about public outreach. B. Chen thinks it is very important, yet challenging, to get information to the public. He hopes that the results of the workshop can be brought to the public in a short and glossy report, which is widely distributed. It may be costly but the impact on public perception would be valuable. C. Doherty hopes that the PIAC will further discuss how to get information out to the public and in what format. J. Pederson feels that the purpose of the workshop needs to be determined -- whether it is to review the science or brief the public. B. Beardsley pointed out that GLOBEC (Global Ocean and Ecosystems Dynamics Research Program) invites science writers to meetings and surveys to help get the information to the public. B. Chen said that the Boston Globe has covered engineering for the Boston Harbor Project. C. Coniaris suggested another insert in the Boston Sunday Globe. J. Pederson pointed out that there are several science writers at MIT who could possibly help. B. Beardsley added that the Japanese prepared a cartoon book describing the sewer system in Tokyo and it was very popular.

ACTION: OMSAP agreed to host a public monitoring workshop this summer. MWRA will develop a proposed agenda for OMSAP/PIAC/IAAC review. A subcommittee will meet to plan for this workshop. Suggestions for meeting format and content are welcome.

PLANKTON MONITORING AND THRESHOLD OVERVIEW
M. Mickelson presented an overview of the phytoplankton (PP) and zooplankton (ZP) MWRA monitoring. There is a map of station locations in his information briefing. M. Mickelson described the concerns raised about plankton:

  • Will nutrients increase, causing more plant biomass and/or higher plankton productivity leading to a dissolved oxygen (DO) depression in bottom waters.
  • Will nutrients increase or will nutrient ratios change causing more nuisance algae which may affect human health and/or the health of higher marine trophic levels.
  • Will nutrients increase or will nutrient ratios change causing a change in the PP community and possibly change the ZP community and possibly change the food web.
  • Will the changed location of effluent discharge cause: an increase in the duration of the spring bloom, abundant growth at depth, and enrichment of Alexandrium entering from the Gulf of Maine.

M. Mickelson then described how monitoring addresses these questions. He showed Bays Eutrophication Model (BEM) predictions for relocation and secondary treatment which show significant decreases of DIN in Boston Harbor and not much change in Mass Bay. There is a decrease in chlorophyll for all locations, especially in the Harbor and at surface depths. The flux of particulate organic carbon (POC) can affect bottom DO and the benthic community. POC model predictions show an improvement in Boston Harbor and no change in Mass Bay, except for a localized increase at the new outfall site. It is not likely in the framework of this model that there would be a disastrous effect. The model has different winter and summer PP communities which have different temperature and silica requirements. B. Robinson asked why POC is presented as a flux and not as a concentration. K. Keay replied that it is a flux to the bottom from the lowest model grid to the sediments to model the effects to the benthic communities in terms of inorganic carbon loading.

M. Mickelson pointed out that the OMP's plankton-related measurements are: nutrients (nitrogen, phosphorus, silica, and carbon) (dissolved, particulate, inorganic, organic), PP (chlorophyll, primary production, microscope counts), ZP (microscopic counts), DO, temperature, salinity, and light. MWRA monitoring is inadequate for properly measuring Alexandrium since it can cause shellfish toxicity even at very low levels. It is best measured by Don Anderson at WHOI (MWRA special studies, Sea Grant) and the MADMF shellfish monitoring program. Zooplankton patches are studied by Cabell Davis, Stormy Mayo and others.

M. Mickelson described general patterns in the plankton results. Overall, there is variability with region, season, and year. The spring bloom is triggered when light conditions are favorable and terminated primarily by nitrogen depletion (secondarily by silica depletion). Chlorophyll and nitrogen are inversely related (i.e. more chlorophyll, more PP, nitrogen depletion). Silica is depleted if diatoms are dominant, especially centric diatoms. Spring blooms may end before completely depleting nutrients (this will be further examined). Nuisance algae have been observed including Phaeocystis and Pseudo-nitzschia. Organic matter from the spring bloom settles and is remineralized by bacteria, releasing nutrients to bottom waters during the summer. Storm-induced mixing events cause small-scale summer blooms due to the mixing of these deep nutrients. Plankton numeric abundances peak during the summer. The fall bloom is triggered by the overturn of the water column which brings nutrient-rich bottom waters to the surface. Bottom water DO is lowest in the fall. The pennate diatom Asterionellopsis often dominates in the fall and the fall bloom is usually larger than the spring bloom (this is an unexpected finding of the OMP).

He described exceptions to the general patterns described above for Boston Harbor (BH). BH has relatively high nutrients and chlorophyll and this signal extends into Mass Bay (MB) surface water. BH has high primary productivity and chlorophyll peaks in the summer (not fall). BH has a similar PP community to MB but has a different ZP community than MB. The BH ZP community is similar to the one found in Cape Cod Bay (CCB).

He then described exceptions to the general patterns described above for CCB. The spring bloom begins earlier in CCB than MB since it is shallower and light can penetrate to the bottom. The spring bloom may be bigger than the fall bloom and may be silica limited. CCB has less summer chlorophyll and ZP abundance. The PP includes more microflagellates and dinoflagellates and the ZP community is similar to coastal MB.

There are three nuisance species of concern. Alexandrium tamarense can cause paralytic shellfish poisoning (PSP). Problem abundances are ~1,000 cells per liter and may bloom from April to June. Pseudo-nitzschia multiseries can cause amnesic shellfish poisoning. Problem abundances are ~100,000 cells per liter and blooms may appear from November to March. Phaeocystis pouchetii blooms produce gelatinous polysaccharide and acrylic acid and may cause the clogging of whale baleen. Problem abundances are ~1,000,000 cells per liter and blooms may appear from February to April. M. Mickelson then described the caution levels for nuisance algae [see handouts], for occurrence of paralytic shellfish poisoning, and for zooplankton community structure in the nearfield. Related thresholds include nitrogen loading, chlorophyll, and dissolved oxygen. PP are sampled using bottle samples at the surface and mid-depth at 13 stations (nearfield 17 times a year and farfield 6 times a year). ZP are sampled using vertical oblique net tows (102 um) through the entire water column at the same stations and frequency as for PP but there are also two additional ZP stations located in CCB, which are measured three times a year during the winter. MADMF has been sampling PSP in shellfish since 1972, and in 1993 there was a large Alexandrium bloom. B. Beardsley pointed out that transport mechanisms are important for Alexandrium.

B. Robinson asked what would happen if a caution level is exceeded. M. Mickelson replied that the first step will be to notify OMSAP and the regulators. J. Pederson stated that there was a lot of discussion initially about the number of plankton samples needed to see a difference and she asked if MWRA takes enough measurements to be able to detect a change given that there is a certain amount of variability to begin with. C. Hunt stated that Battelle is working through the steps to apply a 95th percentile above the mean threshold level. M. Mickelson added that they are first attempting this with simpler measurements such as chlorophyll.

R. Manfredonia asked if there is anything in the plankton record which is surprising. He also asked if there is anything in the baseline record which shows evidence that a change in bloom size will occur with the relocation of the outfall. M. Mickelson replied that it would be surprising if the "textbook" patterns did not occur. One surprise was that the fall bloom was larger than the spring bloom. Another observation is the BH nutrient and chlorophyll signal extending into MB. The similarity of the PP communities in the harbor verses the Bay is important because even with the current nutrient enrichment in BH, manifested by a 3x greater chlorophyll, a marked change in PP community is not seen which suggests that the PP community is not sensitive to nutrient enrichment. MWRA has been comparing each year's results with thresholds in the Outfall Monitoring Overview.

A. Solow asked if a consistent low level of change seen over time, which is not large enough to exceed a threshold, would be a concern. M. Mickelson replied that the threshold formulation is based on the requirement of urgent reporting, and are not expressed in terms of long term effects. K. Keay added that MWRA is currently evaluating what are considered small or large effects and this is something the OMSAP will be asked to review in upcoming meetings. A. Solow feels that it is necessary to be clear about what the purposes of these thresholds are.

J. Pederson stated that one of the problems with looking at subtle changes is that it is difficult to attribute them to the outfall. B. Beardsley and R. Manfredonia feel that MWRA should look at changes other than those which have thresholds and explain them as best as possible. M. Mickelson added that there are certain parameters which are expected to change from the baseline observations and modeling. MWRA should test those as well as possible using future monitoring results. J. Shine feels that everyone needs to make sure that they think about how sampling captures variability over space and time. A. Solow pointed out that the true pre-discharge distribution of parameters is not known.

B. Beardsley gave the example of Georges Bank and how things may be happening over larger time scales than the baseline period. Over the years, there has been a gradual decrease in salinity by about 1.5 psu and it is thought to be due to a larger influx of northern waters. If this is also occurring in MB, it could change plume dynamics over time. A. Solow added that plankton community could also change.

G. Renick gave a brief overview of the history of the thresholds and Contingency Plan (CP). The CP came out of the conservation recommendations attached to the 1993 Biological Opinion (BO) issued by NMFS as a part of the Endangered Species Act consultation. The BO stated that there will be "no jeopardy" to the existence of endangered species but also recognized that there are a number of areas of uncertainty. The CP was developed as a way of trying to identify when significant unpredicted events occur and when they do occur, the outfall should be examined for causality. C. Hunt added that MWRA is trying to set thresholds so there will not be many "false alarms". G. Renick pointed out that it is difficult to determine when something is due to the outfall. B. Robinson agreed with C. Hunt but feels that it is difficult to determine if the nuisance species and shift in ZP community thresholds are liberal or conservative. C. Hunt pointed out that those numbers are based on expert opinions and now MWRA is trying to put data behind those numbers to back them up. Information will be ready on this around June. R. Manfredonia strongly supports looking at the database to gain a better understanding of the system. He feels that the OMSAP should become familiar with the thresholds and raise questions now.

FOOD WEB MODEL SCOPE OF WORK (FWMSOW) STATUS REPORT
A. Solow updated the group on the food web model scope of work. He hopes everyone can come to agreement on this issue. The FWMSOW is required by the draft permit but unfortunately the permit is not very specific. One could infer that the two goals of a FWM, should it ever be constructed, are to enhance our ability to make predictions about the effects of certain changes associated by the outfall on the whales, and detect an effect that could be attributed to the operation of the outfall after the effect had begun to manifest itself. Everyone now agrees that a truly quantitative and predictive FWM is not feasible at this time, but there are other types if FWMs out there. A FWM could be a qualitative description of the food web in the Bays as a way of integrating the results of the monitoring and connecting the results of the monitoring to answer useful questions, e.g. about whales. In thinking about it in those terms, the question then arises, is the OMP missing any important components. Another question is whether the draft scope of work is broad enough to encompass that kind of model. The final point raised is whether the stopping points in the draft FWMSOW, make it too easy to just "start by stopping". A. Solow emphasized that it is not that simple. When a stopping point is reached, missing information is collected and re-evaluation occurs. He pointed out that the PIAC and CCC have requested that the OMSAP postpone any decisions on the FWMSOW so that the CCC can provide OMSAP with a written proposal by April 23 [Update: the CCC has postponed this date].

P. Daley agreed with A. Solow's summary and stated that since the last OMSAP meeting, the CCC had a FWM meeting and came to the conclusion that maybe there is a misunderstanding about what is meant by a FWMSOW. The Cape Cod Commission is not requesting a quantitative food web model or a brand new monitoring program, but rather a different way of looking at the existing data to see if anything is missing. They are considering a qualitative model as a way of integrating the results of the monitoring. The CCC is focusing on the monitoring stations (frequency and timing of sampling) as mentioned by Ted Smayda at the December OMSAP meeting. She will communicate MWRA's plankton presentation back to the group and see if they can formulate a specific recommendation to OMSAP.

M. Delaney commented that what MWRA has done so far is falling in line with the direction from EPA. M. Liebman stated that he had said that the food web model being scoped out did not have to be predictive, but there are differences of opinion in what "predictive" means. EPA would like to see a model which looks at "what if" scenarios. He did not consider this predictive, whereas other people did. J. Pederson pointed out that there is a matrix included in the appendix of the phase 1 OMP which describes these "what if" scenarios. She suggested that the OMSAP review this to see if the current OMP can address these scenarios. This can be considered a type of conceptual FWM, but not with the traditional boxes and arrows. She pointed out that a lot of thought went into determining station locations and there was an awareness that the plankton stations would never be able to give the statistical validity that people are looking for but there were trade-offs such as increased nutrient monitoring. She also suggested reviewing the NRC book, "Managing Troubled Waters".

R. Manfredonia stated that the draft permit did not prescribe any one approach over another as to what kind of model should be developed. EPA understands that MB is a complex ecosystem but EPA does not want to miss any long-term chronic impacts. B. Beardsley pointed out that OMSAP felt that a predictive food web model was not possible at this time but that MWRA could work towards a better understanding of the ecosystem by developing some sort of conceptual food web model.

ACTION: OMSAP postponed a decision on the draft food web model scope of work presented by the MWRA at the December 18, 1998 OMSAP meeting pending additional information from the Cape Cod Commission. OMSAP agreed to review the "Sources of perturbation and resources at risk" matrix on page A-5 of the Outfall Monitoring Plan phase 1 to see if the hypotheses are being addressed with the current monitoring plan. [Update: The matrix has been posted on the web at: http://www.mwra.state.ma.us/harbor/enquad/jk1191a5.pdf Click icon for EPA disclaimer.]

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