Falmouth Ashumet Plume Citizens Committee

July 18, 2003

Mr. Robert L Whritenour, Jr.

Administrator, Town of Falmouth

59 Town Hall Square

Falmouth, MA 02540

Dear Bob:

As a follow-up to our discussion on June 26, here is a report on the 3 1/2 years FAPCC have been studying treatment wetlands to remove significant amounts of N-load generated in the upper watersheds of Great, Green and Bournes Ponds. Because so much time has passed, and many of today’s decision-makers may not be completely familiar with the history, the attached, Exhibit A summarizes the chronology of our examination of treatment wetland potential.

Following the feasibility workshop in June 2002, an ad hoc Science Panel evaluated the

three TW designs outlined at the workshop. We were privileged to have as a member of the panel Robert W Howarth, Ph.D, D R Atkinson Professor in Ecology and Environmental Biology at Cornell and a frequent consultant to EPA. The panel judged the NITREX system to have the best DIN-removal potential; the conventional marsh design proposed by the team that included Robert Knight, co-author of the textbook on treatment wetlands was judged to be second best [see Exhibit B]. There are thousands of such marshes around the country and overseas, but they treat influent DIN concentrations much higher than our streams discharge into the coastal ponds.

Exhibit C describes the role we envision TW systems can perform in removing substantial quantities of DIN generated in the upper watersheds, together with our evaluation of the well tested marsh design and the technologically innovative NITREX concept. Page 3 of Exhibit C compares the potential economic efficiency of TW systems with central plant and on-site wastewater treatment; TW systems appear to remove nitrogen for about 1/10th the cost of the more traditional treatment systems.

Our assessment also underlines how important it is to learn more about the surface DIN

load that actually can be intercepted at the Route 28 culverts. We also need to know more about NITREX performance. Performance of small on-site NITREX units at the Otis Test Center that have resulted in pilot approval from DEP, together with continuing favorable results from experimental NITREX applications that date from as early as 1992, are encouraging pointers but they cannot yet be considered to be conclusive.

Given the potential ecological and economic benefit that could result from NITREX use to treat the surface discharges into our coastal ponds, FAPCC strongly recommends that a pilot program be undertaken to characterize water chemistry and surface flows into Green Pond and to evaluate the performance of a small-scale NITREX unit to determine whether to undertake a full scale application there. The tasks we envision for such a project are outlined in Exhibit D. Recognizing that 18 to 24 months will be required to carry out the proposed project, we urge you to act promptly to contract for the recommended pilot program.

Sincerely yours,

John E [Jack] Barnes, Chairman

Attachments

cc: Ms. Amy Lowell

Exhibit A

FAPCC’s Investigation of Treatment Wetlands Technology

The subject of treatment wetlands to remove N-loading generated in the upper watersheds was first raised in January 2000 when Horsley & Witten suggested it might be fruitful to look into the question of feasibility. Since then, FAPCC has devoted considerable effort in investigating alternative TW designs, performance and potential costs [Exhibit A-1]. To minimize expense, the great majority of that effort has been carried out by FAPCC volunteers.

The initial phase consisted mainly of using local resources, especially Drs. Valiela and Howes, to determine whether the TW concept had enough potential to be featured as a potential core strategy for restoring water quality in Great Green and Bournes Ponds. Although a question about acreage requirements had surfaced, the potential to “solve” the upper watershed N-load problem at modest cost seemed to justify further investigation. Thus, TW is one of three solutions outlined in FAPCC’s assessment and strategies report issued in October 2000.

The next eight months saw extensive effort to identify TW systems in use around the world and evaluations by professional, academic and governmental sources. At that point, FAPCC was still working with H&W’s design concept of a traditional marsh system, and a second core concern was identified: whether such marshes could effectively remove the low concentrations of DIN being discharged from rivers and streams into the coastal ponds --- virtually all the existing TW systems were operating with WWT or storm water effluent with much higher concentrations of DIN. There are thousands of such systems operating in North American and Europe.

By July 2001 FAPCC had identified a number of consultants with TW experience, and had prepared a summary of stream flows, DIN concentrations and other data to support some professional assessments about TW applications north of our coastal ponds. With approval of Selectmen, FAPCC emailed 29 firms and individuals a circular asking for their opinion about TW feasibility in Falmouth and for examples of their experience with similar applications [Exhibit A-2].

By virtue of replies to the circular and follow-up contacts with several of the respondents, FAPCC concluded a TW concept might be feasible but, because conventional marshes might be very land-intensive, alternative designs should be explored. In September, then, six of the most experienced respondents were asked to submit budgets for paper feasibility studies and, in December, Selectmen agreed to contract for three feasibility studies of alternative designs.

In June 2002, the contractors presented feasibility papers on three designs: a conventional marsh; a sub-surface rock filter concept; and a pump and treat system using patented NITREX substrate to supply carbon for de-nitrification. FAPCC assembled an ad hoc Science Panel to evaluate design issues and rank the designs by likely performance results. The Panel assigned 1st place to the NITREX design and 2nd place to the conventional marsh [see Exhibit B].

A series of contacts with the two design teams was required to modify their initial proposals to focus simply on surface water interception and to allow a direct comparison between them. By June 2003, after 3 ½ years of focused effort, FAPCC completed an evaluation of the comparative performance and costs, and recommended that the NITREX design be pilot tested. FAPCC also concluded it is essential to obtain a much better picture of variations in surface water chemistry and stream flows in order to better dimension the amount of N-load from the upper watersheds that effectively can be intercepted in surface water at the Route 28 culverts [see Exhibit C].

Exhibit A-1

Chronology: How the Concept of Treatment Wetlands Developed

Jan 2000: H& W Task 5-6 Report recommends study of treatment wetlands feasibility

Apr 2000: H& W provides FAPCC a technical paper on TW size & design

May 2000: FAPCC holds day-long workshop to develop initial recommendations; decides to include at least a demonstration TW application

Jun 2000: H&W provides tentative layout of TW from converting part of bog on Bournes Brook to free-surface flow wetland; cost of demo program discussed

Sep 2000: Drs. Valiela and Howes provide FAPCC their views on feasibility, potential TW sites

Nov 2000: FAPCC releases findings report, which includes establishing TW feasibility; Town Meeting agrees to seek comprehensive solutions to N-loading beyond USAF funding

Mar 2001: Extensive web search locates more than 2 dozen experienced firms and many other sites that describe TW research and experience [mostly for waste & storm water]

Jun 2001: FAPCC prepares data package prepared to support potential TW feasibility studies

Jul 2001: FAPCC updates Selectmen on project status; Selectmen approve e-mailing firms with TW experience to ask their views on TW feasibility and surface area. Email circular is sent to 29 consulting firms or individuals [see Exhibit A-2]

Aug 2001: After reviewing 23 responses to the circular, and follow-up contacts via email and telephone, FAPCC concludes: [1] TW use seems feasible, but definitely pushes the envelope in respect to influent concentrations; [2] land area will be much more than the H&W estimates; and [3] different design concepts may be needed

Sep 2001: With approval of the Town Administrator, an RFP to study TW feasibility is sent to the 6 most responsive firms; 3 specialize in conventional marsh TW systems and 3 have some experience with other TW designs [see Exhibit A-3]

Dec 2001: FAPCC completes review of responses, and Selectmen approve feasibility study contracts for: [1] conventional marsh design from Sustainable Science team; [2] sub-surface rock filter design from Sustainable Strategies; and [3] a pump and treat de- sign from Lombardo Associates and Professor William Robertson [see Exhibit A-4]

Mar 2002: Contracts signed for a total cost of about $40,000 [USAF processing delays funds]

Jun 2002: Contractors present their papers at a workshop in Town Hall [standing room only].

Aug 2002: Ad hoc Science Advisory Group reviews papers; recommends Lombardo/Robertson concept and Sustainable Science marsh [but with concerns]; see Exhibit B

Nov 2002: After discussion with contractors to restate concept papers for direct comparability, FAPCC issues a draft comparison of performance and cost of the two designs and asks contractors to comment on exhibits of the draft that describe their designs

Jun 2003: Contractors clarify some assumptions and modify their concepts to reduce costs; FAPCC releases revised draft comparison of performance and cost [see Exhibit C], and recommends water chemistry monitoring and NITREX pilot test [see Exhibit D]

Exhibit A-2

Text of Treatment Wetlands Circular: Emailed July 17, 2001

[addressees listed in attachment]

The Town of Falmouth, Massachusetts is being funded by the US Air Force to reduce nitrogen concentrations in three of our coastal ponds. The project has been assigned by our Board of Selectmen to a committee of volunteers, which I chair. The committee=s website www.geocities.com/ashumet2001 provides the initial committee report defining the problem and outlining potential remedies, plus activity updates.

On-site septic systems are the chief source of nitrogen loading and sewering the densely populated peninsulas that border the coastal ponds seems inescapable. The upper watershed areas are considerably larger and less populated, however, and it has been suggested that artificial wetlands could be constructed to intercept much of the nitrogen being generated there. Freshwater ponds and streams are located up gradient and adjacent to the coastal ponds, in areas presently being used for cranberry bogs that are owned in part by the town.

We understand constructed wetlands have shown the ability to remove considerable proportions of nitrogen from wastewater effluent, which obviously contains much higher concentrations than our stream flows. Limited sampling of fresh water immediately above the three coastal ponds has found total nitrogen concentrations ranging from 0.5 to 1.5 mg/L, mainly as nitrate, with discharges of 0.8 to 9.6 MGD.

If it is feasible to apply constructed wetlands to such low concentrations, even if only in the most bioactive warm weather season, we would like to issue an RFP to design, construct and monitor one or more demonstration projects. Thus far, however, we have been unable to determine that feasibility, either positively or negatively.

If you believe that effective removal of nitrogen is possible in our circumstances, and you are interested in becoming an advising consultant or design and build contractor for a demonstration project, please tell us:

1. Why you believe effective removal of nitrogen is feasible in the circumstances described, and roughly how much surface area would be required for the wetland; and

2. Examples of your experience in designing, or knowledge of, constructed wetlands, particularly in regard to polishing systems or other applications that have been successful in treating relatively low concentrations of nitrogen.

Alternatively, if you believe constructed wetlands are not likely to be effective in our circumstances, please tell us that as well. The committee very much desires to reach a feasibility determination, and will give serious consideration to engaging a well-qualified consultant able to demonstrate definitively that our circumstances are not likely to be conducive to use of artificial wetlands for nitrogen removal.

You may contact us at [email protected], by voicemail at 508.540.2392, by fax at 508.540.9584 or by mail at the address listed below or, for express deliveries, at 95 Indian Ridge Road, West Falmouth, MA 02574. Thanks for your interest.

John E Barnes, Chairman

Ashumet Plume Citizens Committee

PO Box 766, West Falmouth, MA 02574-0766

Mount Hope Engineering Inc; James Hall, PO Box 943, Providence, RI 02871 [Lakeville, Swansea]; 401.683.1934, f401.683.1934, www.mounthope.net, [email protected]

Paragon Environmental Consulting; Stephan J White, President, 1400 Providence Hwy., Norwood, MA 02062; [also Aspen, New Haven] 888.660.9975, f781.278.0910, www.paragonenv.com, [email protected]

Tighe & Bond Inc; David G Healey, President; 53 Southampton St, Westfield, MA 01085 [VT, CT & Worcester]; 413.562.1600 f413.562.5317; www.tighebond.com, [email protected]

Capella Consulting Group, Dr. R Jude Wilber, President; and ECO/NH, Mr. William Eustis, President; [email protected]

Geo-Con; Brian H Jasperse, President, 4075 Monroeville Blvd., #400; Monroeville, PA 15146; 412.856.7700; www.geocon.net, [email protected]

J.W. Salm Engineering Inc; John W Salm III, 12432 Collins RD, Bishopville, MD 21813; 410.213.0805, f410.213.0848; www.jwse.com, [email protected]

J.F. New & Associates Inc: James F New, President, 708 Roosevelt Rd, Walkerton, IN 46574; 219.586.3400, f219.586.3446; www.jfnew.com , [email protected]

Waterflow Consultants Inc; John D Eppich, 1506 Alma Dr, Champaign, IL 61820; 217.352.4549; f217.352.4474;www.waterflowconsultants.com, [email protected]

Southwest Wetlands Group Inc; Michael Ogden, 901 W. San Mateo, Suite M; Sante Fe, NM 87505, 505.988.7453, f505.988.3720; www.swg-inc.com, [email protected] Or try [email protected]

Teal Ltd., Susan Peterson, PhD and Partner; 567 New Bedford Road, Rochester, MA 02770; 508.763.2390 or 508.972.1689; [email protected]

CME Associates, Inc; Machael G Shaefer, Director; PO Box 149, Woodstock, CT 06281; www.cmeengineering.com; [email protected]

Massachusetts Institute of Technology; Heidi M Nepf, Associate Professor of Civil & Environmental Engineering; 617.253.4322; [email protected]

Franklin Pierce College; Catherine R Owen, Ph.D., Associate Professor of Environmental Science, Natural Sciences Division, PO Box 60, Ringe, NH 03461 [also NE Chapter, Society of Wetland Scientists]; 608.899.4322, f603.369.8380; [email protected]

Conestoga-Rovers & Assoc.; Fred K Taylor, 651 Colby Drive, Waterloo, Ontario N2V 1C2;

519.884.0510; f519.884.0525; http://craworld.com

Exhibit A-3

Text of Feasibility Study Requests Released September 21, 2001

Thank you very much for your response to the committee=s e-mail circular and other communications in regard to a possible constructed wetlands project. Recognizing the somewhat experimental nature of such a project, we now are soliciting proposals from you and a few other experienced firms to prepare initial evaluations or white papers describing the design approach and construction sites you would recommend, and discussing the implications of significant issues that will determine the feasibility and cost of using constructed wetlands to remove most of the nitrogen from freshwater feeding into Bournes, Green and Great Ponds.

We envisage the preparation of such an initial evaluation will include a brief on-site visit and your review of the following additional data that is provided in the attachments:

(a) Map of land uses around Great, Green and Bournes Ponds [from left to right on the map; Bournes Pond is largely in white because GPS missed the salt water inlet];

(b) Areas of land uses in the three-pond watershed;

(d) Nitrogen loads from the upper watersheds [north of Route 28];

(e) Samples of nitrogen concentrations immediately above the coastal ponds;

(f) Stream flows feeding the three coastal ponds; and

(g) Recent studies of Mill Pond by MBL Ecosystems Center students.

If you would like to participate, please provide us a budget for such an evaluation including a subject outline, the credentials of the individuals who will carry out the work, their hourly compensation, and expected hours. If you believe the budget should be in excess of $10,000 please identify what portion of the evaluation can be accomplished for that amount. Also, please make sure we have all the particulars of a detailed statement of your qualifications.

To encourage creative approaches, we intend to contract with more than one firm at least for the initial evaluation phase. Subsequent contracts, if any, will depend principally on the outcomes of the initial evaluations, including the feasibility, potential benefits and likely costs to apply the concepts identified therein to all three coastal ponds.

Please provide us your written responses in 12 copies by November 2, 2001. If you have any questions about this solicitation, please call me [508.540.2392] or e-mail us at [email protected] with a copy to [email protected]. We also would appreciate receiving an electronic version of such responses suitable for e-mailing. Thanks again for your advice to date; we look forward to hearing from you on November 2.

Sincerely yours, John E Barnes, Chairman, Falmouth Ashumet Plume Citizens Committee

Addressees:

Pio Lombardo, Lombardo Associates, Inc.; 49 Edge Hill Road, Newton, MA 02467

Stephen McCann, Geo-Con, Inc.; 4075 Monroeville Blvd #400, Monroeville, PA 15146*

David Del Porto, Sustainable Strategies, 50 Beharrell Street, Concord, MA 01742

Carl Tammi, ENSR International; 2 Technology Park, Westford, MA 01886-3140

Andrew Bender, J F New & Assoc., Inc.; 3955 Eagle Creek Pkwy, Indianapolis, IN 46254

Jude Wilber, Capella Consulting Group, PO Box 464, Woods Hole [mailed October 12]

* Response came from team of Albert McCullough, Sustainable Science LLC, Denton, MD [engineering consultants to Geo-Con]; Robert L Knight, Wetlands Solutions, Inc., Gainesville, FL; and Richard Claytor, Horsley & Witten, Inc., Sandwich, MA. Team usually referred to as ASustainable Science@ [despite opportunity for confusion with Sustainable Strategies].

Exhibit A-4

Request to Selectmen for Feasibility Studies: December 10, 2001

Background: Following the round of answers to our e-mail circular about using treatment wetlands to remove nitrogen from fresh water up gradient of the coastal ponds, Bob Whritenour approved release of an RFP seeking feasibility evaluations of such wetlands to be located immediately north of Great, Green and Bournes Ponds. RFP=s were sent to five firms whose responses to the e-mail circular indicated considerable experience with and interest in pursuing such projects. All five responded, and two proposed internationally recognized experts for their teams. A proposal also came in from a local environmental consulting group.

Scope of Work: Although there are differences in detail, most proposals include these tasks:

1. Review of potential sites and existing data on water flow, nitrogen content, etc.

2. Recommended design approach and preferred site for each pond

3. Estimates of performance, cost and land area required for each design/site

4. Assessment of determinative issues such a permitting to reach a go/no go decision

In addition, we plan to ask the selected contractors to present their papers here at a 2 day workshop where the pros and cons of various design approaches could be addressed in order to help the Town decide whether to fund one contractor for a demonstration program. It is planned to invite representatives of DEP, Cape Cod Commission and any other permitting agency to attend the workshop, together with Falmouth officials and interested staff.

Contract Cost: The proposals range from $10,000 to about $13,000 largely depending on whether the teams include internationally recognized consultants to the proposing firms. Depending on details of the workshop and certain other useful features that some bids include and others do not, it is likely the final fixed price would be $15,000 or less per firm. In order to take advantage of the expertise being offered, and to have more than one design approach evaluated, we recommend and Bob Whritenour supports contracting with three firms.

Ranked Firms: Lombardo Associates of Newton [with Professor William Robertson of Waterloo University in Ontario] and Sustainable Science LLC of Denton MD [the design arm of Geo-Con, with Robert L Knight] ranked in the top 3 of most scorers. To obtain what we expect would be a clearly different design approach, we also would choose Sustainable Strategies of Concord C pending a review of their treatment wetland facility in Weston.

The other firms are ENSR of Westford [wetland experience is chiefly with hazmat], J F New of Indianapolis, IN [greatest experience but briefest response] and Capella Consulting-ECO/nh- Salm Engineering [lacks comparable experience, few deliverables defined].

Next Steps: We understand Bob Whritenour has authority to sign contracts of this size. After we discuss the workshop and certain other details with the three top firms, and Frank Duffy is happy with the form of contract, we hope Bob can sign the contracts before yearend. With that approval timing, the evaluations should be available before Spring Town Meeting. The workshop probably would be held later in April.

Exhibit B

Constructed Wetlands (CW) Science Subcommittee Report

O. Zafiriou, K. Foreman, J. Barnes

(APCC)

with

R. Howarth - Cornell and Kevin Kroeger/ -MBL/BUMP (Volunteer Consultants)

M. Emslie -Falmouth ConCom - Observer

Executive Summary

Consensus findings and recommendations on science aspects of CW systems

(excluding "riparian" = "reactive trenches") - proposals by Lombardo Associates, Sustainable Science (Knight), and Sustainable Strategies, (del Porto) - are:

· Proceed with Nitrex pilot tests after cost- and site- availability screening.

· Develop scientific aspects of riparian (pondshore-trench) approaches and tests.

The bases for these recommendations are:

Key Questions Addressed: A. Can the approach remove the amount of N claimed, with high probability? B. If A. is promising but unclear, can pilot tests (or other work) increase confidence? C. If "Yes" to A or B., what are the risks in areas of hydrology, plant life, wildlife, "nuisance problems," and premature system failure?

General Criteria Used. What are N removal pathways: denitrification (permanent)? Conversion of N to PON or DON (possibly temporary)? Are "reactive" DON effluents low enough?? (D = dissolved, P = Particulate, ON = Organic Nitrogen).

Evaluation of Proposals: N removal and Downside Risks. Lombardo's "NITREX" approach - with an aerobic front-end to process DON - is promising and merits evaluation by added inquiries, then by to-be-specified pilot studies. Knight's "CW Marsh" probably requires too much land; its DON emissions may matter. (If NITREX fails, CW marshes might be pilot-tested using a bio-diverse mix of native plants - e.g., in former cranberry bogs). Del Porto's "planted rock filter" should be shelved: its crucial source of carbon is unclear and it lacks scientific or empirical precedent. Small NITREX systems seem low in plant, odor, and insect risks, but its impacts on stream water quality, especially on fish (herring) migrations, must be studied. The NITREX wood-chip substrate may settle channel, and deteriorates over time; over years (10-?) it must be replaced. Can the old residue be left in place as more is added? If not, is it an acceptable soil amendment, or a disposal problem?

Appendix B

Constructed Wetlands (CW) Science Subcommittee Report

(Subcommittee of the Ashumet Plume Citizen's Committee of Falmouth)

O. Zafiriou, K. Foreman, J. Barnes

Background and Scope

APCC is pursuing a three-pronged approach to Nutrient (Nitrogen) remediation: 1. creating Falmouth-wide Nutrient Management Districts, 2. community outreach to minimize fertilizer use, and 3. evaluating constructed wetlands (CW) as possible cost-effective alternatives to conventional denitrifying remediation (individual or sewers to cluster or central treatment).

After the workshop at which three CW proposals were presented and discussed, the initial idea was expanded to two approaches, A. "constructed wetlands" as originally proposed, and B. "riparian" (meaning "reactive wall" trenches strategically sited along pond-edges). This report is the result of a review of the proposals and one-afternoon working session that focused on the scientific aspects of the CW approaches, with a few related remarks about "riparian " ideas.

Approach

After pre-meeting digestion of the proposals and other materials in light of the questions posed by the full committee (Appendix 1), discussion focused around three questions:

1. Can the proposal (with or without a pilot study for further definition) likely remove about the amounts of N claimed effectively, or not?

2. What are likely negative consequences of initiating proposals that can remove N?

3. If/when a project fails or needs rebuilding, what are the scientific consequences?

Criteria for N removal

The sum of nitrate-N (actually Nitrate + Nitrite N) and ammonia-N equals dissolved inorganic nitrogen (DIN), the main species eutrophying N species prior work focused most heavily on measuring and removing. The most important finding of the science evaluation was a better appreciation of the need also to maximize removal of Dissolved Organic Nitrogen (DON). [Prior data on DON and DIN loads in streams were tabulated by Jack Barnes [Appendix 2's Attachment (2^nd page) ]. DON is a complex mixture of N compounds that ranges from unreactive to very reactive over the time for freshwater to pass through our salt ponds. Recent data by K. Kroeger show that about half of the DON is bio-available in a 5-day period (with wide variation). DON levels can vary widely but often roughly equal to DIN, so reactive DON may contribute very roughly one-third of the total bio-reactive N loads to ponds. This possible role of reactive DON leads to several key points:

1. Focusing on very high levels of DIN removal alone may not suffice if the reactive DON component is substantial.

2. For none of our stream waters is the reactive fraction of DON very well measured at all, especially under the biological conditions encountered when it enters the salt ponds.

3. None of the proposed wetland removal systems is very well characterized with respect to extent of DON removal; efficiencies seem to be low, and formation of new DON is plausible

4. Actively growing plant systems may remove some N, but also tend to emit some nitrogen (mainly DON and ammonia) as a general biological principle, thus setting the system's N output above zero. These balance-point levels effluent N levels are unknown but might be approximated by measurements in natural local marsh systems, and possibly for CW systems at pilot scales (after their vegetation communities mature).

Given 1-4 above, at present no CW or riparian system can be recommended a priori, without a better understanding (probably from pilot-scale studies) of the "DON issue": A. what is the amount of reactive DON is the surface waters of the three streams (for CW approaches); B. What is the amount reactive DON in groundwaters entering ponds (for riparian solutions)?.

Pilot design issues

Given this fact, the discussion turned to initial ideas about pilot studies. Here, it seems that systems involving plant communities are inherently slow to reach a point where the results have predictive value, because the plant communities must mature (requiring more than one season)., whereas system dependent mainly on microbes may reach at a least a rough "steady state" in much shorter periods - they might not be the best, but they are the most testable. Microbially -based systems can also likely be tested on a much smaller physical scale (perhaps a few cubic meters); a plant wetland probably must approach the size of a cranberry bog for revaluation.

Possible negative impacts.

Given the complex issue above, these were passed over somewhat lightly. Again, the plant-based systems are at least more complex to evaluate (e.g. for insects, wildlife effects, effluent effects on fish and fowl etc, though microbial systems also have possible problems, such as odors and re-oxygenation of the effluent, and "smell" issues affecting fish behavior (herring migration?). System removal complexity is unclear but clearly bigger.

The Constructed Wetlands Proposals:

Lombardo Associates. Because of their demonstrated high efficiency over ~7 year periods and their favorable testability, the microbially based "NITREX" systems of Lombardo/Robertson (in which wood-derived materials provide carbon "fuel" for bacteria to denitrify nitrate and nitrite N) are the most favorable. However, their DON removal is undemonstrated and there may be issues involving the woody substrate, which gradually is used up (possibly leading to settling of the bed, channeling, clogging, or other losses in efficiency or hydrological problems). There might be we disposal issues and costs when the spent bed is replaced unless spent material is small in volume

and so can be left in place. Nonetheless, these carbon-fed microbial systems show the best combination of proven N removal ability and testability for the DON and other issues of concern.

We recommend proceeding to design/ implement a pilot study, provided that the concept passes APCC's other nonscientific review criteria (cost, social acceptability, time-scale, siting etc.)

Knight et al.'s conventional constructed wetlands proposal can also remove large amounts of N over large areas and is a well- tested approach, albeit one with poor predictability for efficiency of removal at low N concentrations and in our climate/soil conditions. It requires- roughly all of the lowlands in the Coonamessett R. Valley, and the time- and space-scales of good pilot tests are much more demanding (thus, likely much more expensive). The DON problem, though not understood, seems more likely to be difficult than with microbial-alone systems. (A related consideration is that there are plans to allow the vegetation in the Coonamessett River Valley to "naturalize" - at no cost to N -remediation funds. If this change occurs, it would both decrease N inputs due to cessation of bog fertilization, and likely would - slowly and to an unknown extent - function as a denitrifying wetland, especially if the "naturalizing" management favored large areas of waterlogged soils). Thus, we recommend that Knight et. al.'s CW systems proposal be set aside as "second most promising" while the NITREX concept is pilot-tested.

del Porto et al. proposed several systems involving plants, which, though smaller, have the negatives cited above for the CW, but less thorough documentation or precedent. Their final proposal is for a "rock filter" with no plants that has no clear source of the carbon or "reducing equivalents" needed to denitrify. We do not understand how it works from first principles, and that group has not yet provided promised quantitative empirical evidence from their existing systems showing that it does work, even if it is not understood. At present we cannot recommend further work on these systems.

Riparian systems

A general discussion of these concepts revealed that they are seen as very experimental, potentially promising (they alone might intercept sewage N and also much of the rain input of N), but in need of careful refinement in design and in evolving a feasible pilot-test protocol. Provided that the CW concept and/ or the reactive wall concept passes APCC's nonscientific review criteria (cost, social acceptability, time-scale, siting etc.), we recommend that a working group be formed to refine ideas about pilot tests of the NITREX system for streams, and also for the general "reactive wall": concept as it might apply to the shores of salt ponds in Falmouth.

Exhibit C

Treatment Wetlands: Purpose, Configuration, Performance and Cost

This paper describes the potential use of treatment wetlands to reduce the pollution of coastal ponds from nitrogen being generated in the upper watersheds of Great Pond, Green Pond and Bournes Pond. Those upper watersheds are very large areas where it will be very expensive to install sewers or on-site de-nitrification systems. They also generate so much nitrogen that it will be difficult, if not impossible, to achieve reasonable water quality in our coastal ponds without removing a major part of that N-load. The first section of the paper addresses the upper watershed nitrogen sources and loading being generated there.

The next sections compare two very difference design concepts of treatment wetlands. The first is a conventional constructed marsh system that is recommended by a team that includes Robert L Knight, co-author of “Treatment Wetlands”, the definitive textbook on the subject. The second system is an innovative “pump and treat” approach that uses treatment cells located away from wetland areas to denitrify in a patented media called “NITREX”. The NITREX-based design offers a smaller footprint and superior N-removal performance for modestly higher capital expenditures and substantially lower annual maintenance expense.

The NITREX-based design also offers superior cost efficiency in removing nitrogen loading from the upper watershed areas in comparison with central wastewater treatment or onsite nitrogen removal. Moreover, unlike such systems, it addresses nitrogen accumulation in groundwater over many years, and would have an immediate impact on nitrogen loading to the coastal ponds.

The concluding section recommends taking the next step to better characterize levels and variations in water chemistry and to carry out a small-scale NITREX pilot test program.

Upper Watersheds: The upper section of Great Pond=s watershed, especially, is very large. That section covers 3237 acres or 64% of the land of Great Pond=s watershed located inside Falmouth [another 1260 AC in the MMR]. Green Pond=s upper watershed area is 1075 acres, or 52% its watershed land in Falmouth [another 575 AC in the MMR]. Conversely, Bournes Pond=s upper watershed of 348 acres represents only 37% of its watershed land area [none in MMR].

There were almost 2300 homes in the upper watersheds in 1999, and that number will grow to nearly 3100 at buildout with an average annual population of about 5800. At buildout, Great Pond will have 2328 homes, Green Pond 580 and Bournes Pond 180 [Exhibit C-1]. Those homes will account for the following proportions of the total number of homes in the entire watershed of each coastal pond: Great Pond 52%, Green Pond 26% and Bournes Pond 19%.

Nitrogen loading to the coastal ponds from the upper watersheds comes from home septic systems, fertilizer [lawns, golf course and bogs], and the atmosphere. Some of that nitrogen load is removed by passing through freshwater ponds and streams, however, and the Great Pond watershed has disproportionately more of such water bodies than the others. As a result, the upper watershed will contribute 42% of the total nitrogen load to Great Pond at buildout. The same percentages are 31% for Green Pond and 20% for Bournes Pond [golf courses cause the N-load percentages to exceed the home percentages].

Surface waters carrying those nitrogen loads differ greatly in volume of stream flow. On an average day, the Coonamessett River carries 9.6 million gallons of freshwater into Great Pond, compared with 1.7 million gallons from Backus River/Mill Pond into Green Pond, and 0.8 million gallons from Bournes Brook. Based on limited sampling of nitrogen concentrations, it appears that substantial portions of the net N-load generated in the upper watersheds can be intercepted in surface discharges in the area of Route 28 [Exhibit C-2]. Route 28 more or less marks the southern limit of freshwater and the northern limit of saltwater.

The proportion of upper watershed N-load likely available to be intercepted there varies from 97% to 100%+ for Great Pond, 52% to 84% for Green Pond and 62% to 92% for Bournes Pond. Such a range of N-load in surface water discharge samples underlines the imprecision of all estimates of N-load sources, and the need to develop more data on levels and variations of water chemistry [especially N-concentrations and DIN proportions] before making major financial commitments to a treatment wetlands design strategy.

Nevertheless, there are some concrete factors that support a strategy of removing nitrogen from surface discharges at Route 28 rather than at the N-source in the upper watershed, in spite of having to treat much greater volumes of water in those discharges:

Cost: The cost to construct a marsh system for all three ponds is estimated at about $3.6 million, including $1.4 million to buy the Backus River and Bournes Brook parcels [@ $10,000 an acre] and $520,000 for a pump system to treat half the Coonamessett River volume in converted bogs along the Backus River [Exhibit C-5]. Annual operating costs are estimated at $690,000 C chiefly labor for cultivation and berm maintenance, and compliance monitoring

The cost to construct a NITREX design system for all three ponds is estimated at $4.1 million, assuming independent units for each pond and no land acquisition costs [Exhibit C-7]. Operating cost is estimated at $375,000/yr [includes a 20-year reserve to replace NITREX].

As summarized in the following table, the NITREX design appears to offer the greatest efficiency in capital cost per kg of nitrogen removed compared a marsh or source treatment:

Capital Nitrogen Removed [kg/yr]

Cost [000] Total Annual Cost per Kg

Treatment Wetlands

Nitrex-based system $ 4,125 5800 kg $ 711

Constructed marsh 3,571 4123 866

Source Treatment*

Central WWT Plant 62,000 5920 10,473

On-site De-N Upgrade 25,000 4050 6,173

* Nitrogen removal amounts reflect 95% effectiveness for WWT plant and 65% for on-site upgrade and Tables 7&8 of the CMAST/H&W Task One Report for buildout net septic load]

Assuming the assumptions about DIN interception [Exhibit C-3] are reasonable, a NITREX-based surface water system would remove nearly as much nitrogen as sewering the entire upper watershed, but cost less than $800 per kg of nitrogen removed compared with $10,000 per kg removed by a WWT plant.

Conclusion: If the performance and cost estimates for the NITREX-based system can be verified in field trials here in Falmouth, using it to intercept and treat surface discharges near Route 28 represents the most effective and cost-efficient overall approach to addressing pollution of the coastal ponds from nitrogen loading in the upper watersheds.

There is one other cost-related point to consider. Half the nitrogen generated in the upper watershed of Bournes Pond comes from golf course and cranberry bog fertilizers. It may be more cost efficient to eliminate that N-load through better management practices and onsite treatment [e.g. a settling pond] than constructing a $375,000 system to intercept at Route 28.

Such an approach would make it attractive to combine NITREX treatment for Green and Great Ponds at one site. Further, recognizing that: [a] northern reaches of Green Pond have the worst nitrogen pollution of the three ponds; and [2] Backus River/Mill Pond has both the highest freshwater concentration of nitrogen and a stream volume only 18% that of the Coonamessett River, seems sensible to focus on Green Pond to test and potentially develop an application that could be extended to Great Pond after prove-out at Green Pond.

Therefore, FAPCC recommends that a contract(s) be let to characterize water volume and chemistry for a Green Pond system, with an option to collect similar data for the Coonamessett River, and to operate a small NITREX test cell --- perhaps trailer-mounted to enable alternative intake sites to be examined --- for a period of 12 to 24 months.

Exhibit C-1

Homes and N-Load: Upper vs. Lower Watershed Areas

(homes include equivalent dwelling units)

Great Green Bournes Total 3 Memo: Pond Pond Ponds Ponds % Total

Homes in 1999:

Upper Watershed 1741 474 78 2293 36% Lower Watershed 1948 1491 591 4030 64

Total 1999 Homes 3689 1965 669 6323 100%

Homes at Buildout*:

Upper Watershed 2328 581 180 3089 40

Lower Watershed 2194 1664 789 4647 60

Total Buildout Homes 4522 2245 969 7736 100%

Memo: Upper % at Buildout 52% 26% 19% 40%

N-Load in 1999 [kg/yr]:

(after attenuation**):

Upper Watershed 8155 3618 877 12650 33% Lower Watershed 12990 9034 3957 25981 67

Total 1999 N-Load 21145 12652 4834 38631 100%

N-Load at Buildout [kg/yr]:

Upper Watershed 10218 4347 1139 15704 35

Lower Watershed 14191 9898 4575 28664 65

Total Buildout N-Load 24409 14245 5714 44368 100%

Memo: Upper % at Buildout: 42% 31% 20% 35%

* Based on developable and potentially developable parcels per Falmouth Planning Office definitions.

Parcels less than 2 acres assumed to support only 1 new house; 2.5 houses for 2-3 acre parcels; 3.5 houses for 3-4 acre parcels; 4.5 houses for 4-5 acre parcels; 5 houses for parcels greater than 5 acres.

The present average annual population per house is assumed to be 1.86 persons, and the N-load at buildout assumes no increase in that density. At the national average rate of 2.7 persons/house, N-loads would be 24% higher than shown above.

** Much of the upper watershed N-load filters through fresh water streams and ponds that provide natural de-nitrification, which is assumed to reduce the N-load by 30% to 60%, depending on the type of water body [see Exhibit C-3 for attenuation effects].

Exhibit C-2

Upper Watershed N-Load and Measured Discharge At Rt. 28

1999 Conditions [kg/yr] ]

Great Green Bournes Total 3

Pond Pond Pond Ponds

Un-attenuated N-Load

Septic Systems 6165 1605 260 8030

Fertilizers 3410 2188 622 6220

Atmospheric Deposition 4654 1375 371 6400

Total Un-attenuated N-Load 14229 5168 1253 20650

Less: Attenuation* 6074 1550 375 7999

Attenuated N-Load

Septic Systems 3534 1124 182 4840

Fertilizers 1954 1531 435 3920

Atmospheric Deposition 2667 963 260 3890

Total Attenuated N-Load 8155 3618 877 12650

==== ==== ==== ====

Measured Discharge at Rt. 28** 7918 2851 812 11581

Percent of Attenuated N-Load 97% 79% 93% 92%

Memo: Sampling Variation***

Low Discharge Estimate 7918 1904 544 10366

High Discharge Estimate 9921 3044 812 13777

Note: Sampling % DIN****

Low Sample Inorganic N 68% 74% 56%

High Sample Inorganic N 80% 86% 80%

* Applied pro-rata to each contributing un-attenuated source, by watershed.

** From CMAST samples of N-concentrations and actual discharges at Route 28 culverts in November-March 1998-99.

*** Lows and Highs reflect Pondwatcher samples of N-concentrations in July/August over several years, and USGS model average annual discharges for all samples.

**** Dissolved Inorganic Nitrogen, mainly Nitrate, as a percent of total dissolved nitrogen; the remainder is Organic Nitrogen [DON]. Nitrate is removed by de-nitrification under anaerobic conditions. Some portions of DON can be removed in aerobic conditions. With the passage of time, most DON is expected to actively stimulate biological growth.

Exhibit C-3

Upper Watershed N-Load Intercept Assumptions

Great Pond Green Pond Bournes P Total

Gross N-Load Generated [yr] 12,978 kg 6,209 kg 1,627 kg 20,814 kg

Less: Attenuation 2,760 1,862 488 5,110

Net N-Load Generated [yr] 10,218 kg 4.347 kg 1,139 kg 15,704 kg

Net N-Load Intercepted

Percent* 95% 75% 90% 89%

Amount [yr] 9,705 kg 3,260 kg 1,025 kg 13,990 kg

DIN Intercepted

Percent** 65% 70% 55% 67%

Amount [yr] 6,310 kg 2,285 kg 565 kg 9,325 kg

Memo: DIN Intercepted %

of Net N-Load Generated: 62% 53% 50% 59%

Stream Flow [USGS]

Million Gallons per Day 9.6 MGD 1.7 MDG 0.8 MGD

Million Liters per Year 13250 MLY 2350 MLY 1150 MLY

DIN Concentration [mg/l] 0.48 mg/l 0.97 mg/l 0.49 mg/l

Note: DIN Concentrations @

High Sample Percentages: 0.59 mg/l 1.19 mg/l 0.71 mg/l

* Measured discharge at Route 28 percentages [Exhibit C-2] rounded down.

** Low percentage samples of DIN [Exhibit C-2] rounded down

Exhibit C-4

Conventional Treatment Wetlands: Configuration, Operation and Performance

[Concept Design of Sustainable Science LLC, Denton, MD]

Configuration: A conventional surface flow system slows and spreads stream flow through a large area of marsh dominated by cattails and other emergent plants. To control water flow and distribution, the wetland is subdivided into a series of cells that lead from central levees built on each side of the original stream. Berms that reach from levee to bordering upland form the other sides of the cells. A series of such cells gradually declines in elevation to provide gravity flow through the system. The area between central levees can be a fish run.

Stream water enters the up-gradient cells through a water control structure, is distributed side-to-side by deep zone trenches, flows uniformly through the shallow planted marsh into another deep zone trench where the flow is channeled to another water control structure that connects to the next cell downstream. The planted marsh is a few inches deep while deep zone trenches have a minimum depth of 3 feet [access must be limited]. The last cell down gradient empties into the original stream via a waterfall or other aerator to restore oxygen after de-nitrification.

Existing bog formations are converted to cells where they are well sited. The Coonamessett bogs are an exception; only 32 acres of bogs are easily convertible, but there is excess bog area that can be converted along the Backus River. About half the Coonamessett’s flow would be diverted from Pond14 to the excess Backus bogs, treated there and pumped back to the area of the Pond 14 fish ladder. The acreage affected is summarized as follows:

Coonam. Backus Bournes 3-Pond

Great P. Green P. Bourn.P. Total

Estimated Acres:

Converted Bogs 32 AC 58 AC 22 AC 112 AC

Other Bog area in parcels 33 - - 33

Upland in Parcels* 105 29 31 165

Total Parcel Acreage 170 AC 87 AC 53 AC 310 AC

____

*Excluding 4 AC estimated for a private home [Backus River].

The Town owns the acre Coonamessett parcel where 32 acres of bogs south of Pond 14 are converted to marsh cells; the remaining bog area and upland is available for passive recreation or other activity. All the bogs along the Backus River and Bournes Brook also are converted, for a total of 112 acres of bogs converted. But it seems doubtful the Town could purchase only the needed Backus and Bournes bog acreage where existing parcels amount to 87 and 53 acres, respectively. Thus, the conventional marsh design impinges directly or indirectly on 310 acres.

Operation: Marsh systems remove DIN mainly by de-nitrification in sediment and plant root zones, using carbon supplied by the plants. The plants also take up small amounts of nitrogen, help to stabilize cell surfaces, and shade the trenches to promote anaerobic conditions for de-nitrification. Maintenance mainly involves plant cultivation [no harvesting] and repair of levees, berms and trenches; berms and levees are sized for 20 years between refurbishment.

Performance: Citing the extensive Treatment Wetland Database, Sustainable Science projects the marshes would discharge DIN at concentrations of 0.30 mg/l. Assuming the Exhibit C3 N-load intercept assumption are valid, the marshes would remove 37% of Green Pond’s upper watershed net N-load, 27% of Great Pond’s and 27% of Bournes Pond’s {Exhibit C-5].

The Science Panel is concerned that such low concentrations might not be achieved, however, and that the marshes could export enough DON to compromise N-removal results. Further, there is no effective way to test a converted bog in less than the 3-4 years needed to grow the plants, the plants are subject environmental factors that affect growing crops, and there also is a concern over mosquito control when stream flows decline in summer months.

Exhibit C-5

Conventional Marsh Design Performance and Cost Summary

[excludes water characterization and any pilot testing costs]

Great Green Bournes Total

Pond Pond Pond 3-Ponds

Performance Factors:

Stream Flow [mil gallons/day] 9.6 1.7 0.8 12.1

Wetland Size* [acres] 32 58 22 112

Memo: Parcel Size [acres] 170 87 53 310

Buildout DIN Removal [kg/yr]:

Inflow 6310 2285 565 9160

Discharge 3996 708 333 5037

DIN Removed 2314 1577 232 4123

DIN Removed % Net Upper

Watershed Net-N Load** 23% 37% 27% 27%

Memo: DIN Concentrations

Inflow [mg/l] 0.48 0.97 0.45

Discharge [mg/l] 0.30 0.30 0.30

Construction Costs [000's]:

Cell Conversion [incl pumping]* $ 803 $ 514 $196 $1513

Plants & Planting 63 116 44 223

Land Purchase*** n/a 870 530 1400

Subtotal $ 866 $1500 $770 $3136

Design & Permits [25%]*** 217 158 60 435

Total Construction Costs $1083 $1658 $830 $3571

==== ==== ==== ====

Annual Maintenance [000's]:

Labor, compliance, berm replen. $200 $350 $135 $690

* Green Pond includes extra acres to treat flow diverted from and returned to Great Pond. Great Pond Cell Conversion includes $520,000 to construct flow transfer piping and pump stations.

** Includes minor amounts for residual DIN [i.e. discharge <0.30 mg/l] from bog fertilizer

*** Assumes a purchase price of $10,000/ acre for the entire Backus and Bournes parcels that the Town does not own presently; not included in base for design & permits provision.

Exhibit C-6

NITREX Remote Treatment: Configuration, Operation and Performance

[Concept Design of Lombardo Associates, Newton, MA]

Configuration: Surface stream flow is intercepted upgradient of the coastal ponds and pumped to a remote, upland location for treatment. The treatment is carried out in a series of cells that denitrify Dissolved Inorganic Nitrogen [DIN], chiefly nitrate, by passing through the patented NITREX reactive media with which the cells are filled. The excavated cells are four feet deep and lined with an impermeable barrier; surface areas can be planted for a minor N-removal benefit, or left unplanted in gravel at ground level; security fencing is not needed. Cells can be added for reserve or growth in processing capacity. After treatment, water is re-aerated and returned downstream of the intake [a small dam and fish ladder separates intake and discharge to avoid mixing]. The facility can operate year-round or go off line during fish runs.

Surface area of the cells is relatively small C about 3 acres for all three ponds [Exhibit C-6]. The cells could be screened with a buffer zone; a 200-foot buffer would add 23 acres, raising total size to 26 acres for three freestanding facilities. By adding extra length to intake and discharge lines, sites can be combined and buffer area reduced; for example, freestanding facilities for Great and Green Ponds would use 19½ acres, but one site for both with 200-foot buffer would use only 15½ acres. Several town-owned parcels could house treatment facilities.

Operation: The NITREX media contains wood chips, sawdust and other waste cellulose solids that supplies the carbon required to convert Dissolved Inorganic Nitrogen [DIN], mainly Nitrate, into inert nitrogen gas. NITREX was developed by Professor William Robertson of Waterloo University in Ontario and has evolved through a series of field trials. Projects treating wastewater or farm run-off have been in semi-continuous operation since 1992, and mass balance calculations indicate that carbon consumption has been only 2-3%. When the carbon in a NITREX cell is depleted, the media is removed [perhaps pumped out] and replaced with fresh NITREX. Disposal of exhausted substrate, while unevaluated and lacking a track record elsewhere, is not likely to be a major issue. To minimize channeling inside the cell, water is pumped into the bottom on one side of the cell and discharged at the top on the opposite side.

After successful testing at the Alternative Septic System Test Center at Otis, the Commonwealth has given experimental approval for a limited number of NITREX onsite installations. As with the NITREX field tests, however, the scale of treatment cells contemplated for the East Falmouth ponds is orders of magnitude larger than NITREX applications tested in the field to date.

Performance: Otis and other test data show potential to reduce nitrate-DIN concentrations to less than 0.1 mg/l. Lombardo Associates estimates DIN mass reductions based on average annual discharge concentrations of 0.1 mg/l and 0.3 mg/l. If the discharge is 0.2 mg/l, mid-point of the range, and DIN intercept assumptions {Exhibit C-3] are accurate, the system would remove 42% of the Net N-load generated at buildout from the upper watershed of Green Pond, 36% of the UW N-load of Great Pond and 30% of the UW N-load for Bournes Pond.

As an engineered system with extraction, treatment and discharge functions all internally controlled, the effect of full-scale operations should be predictable from pilot tests in miniature cells, which can be sited away from wetlands with small lines for intake and discharge. Similarly, it should be possible to predict likely intercept volumes and DIN content for single-point intercept sites by conducting studies to better define variations in water flow and chemistry.

From the standpoint of construction and operating costs, the key variables are residence time in the cells and carbon availability. Test results suggest a residence time of 4-hours is adequate, but the cell size estimate is based on 8 hours to be conservative; pilot testing would establish residence time performance and cell size requirements. NITREX carbon life is assumed to be 20 years, which can be evaluated from sampling of NITREX media in long-term use. On the other hand, limited-duration testing should allow evaluation of short-term trends in hydraulic conductivity [clogging/settling] that also may limit the ultimate life of NITREX media.

Exhibit C-7

NITREX Design: Performance and Cost Summary

[excludes water characterization & pilot cell testing costs]

Memo:

Great Green Bournes Total Great &

Pond Pond Pond 3-Ponds Green*

Performance Factors:

Stream Flow [mil gallons/day] 9.6 1.7 0.8 12.1 11.3

Wetland Size [acres]:

Treatment Cells 2 ½ ½ 3 2 ½

Buffer & Other 10 ½ 6 ½ 6 23 13

Total Wetland Size [acres] 12 ½ 7 6 ½ 26 15 ½

Memo: Parcel Size -- -Not applicable; use Town-owned land--

Buildout DIN Removal [kg/yr]:

Inflow [from Exhibit B-3] 6310 2285 565 9160 8595

Discharge [0.02 mg/ltr] 2660 475 225 3360 3135

DIN Removed 3650 1810 340 5800 5460

DIN Removed % Net Upper

Watershed Net N-load 36% 42% 30% 37% 38%

Memo: Nitrogen Concentration

Inflow [mg/l] 0.48 0.97 0.45

Discharge [mg/l]** 0.20 0.20 0.20

Construction Costs [000's]:

Cells, Pumps, Lines, Etc. $2400 $ 600 $ 300 $3300 $2640

Design & Permits [25%] 600 150 75 825 660

Total Construction Costs*** $3000 $ 750 $ 375 $4125 $3300

==== ==== ==== ==== ====

Annual Maintenance [000's]: includes

power, labor, parts, compliance and

20-year substrate replacement reserve $260 $ 75 $ 40 $375 $320

* Treatment cells co-located on the same site to minimize buffer size and utility construction; increase operating flexibility; and [c] focus administration and compliance.

** Mid-point of Lombardo Associates’ estimated range [0.1 to 0.3 mg/l. If 0.1mg/ discharge could be achieved, discharge amounts would be half those shown and the percents of Upper Watershed Net N-load removed would be: 49%, 47% and 40% for Great, Green and Bournes Ponds, respectively. Actual discharge objective to be set after pilot test determines trade-offs between cell size, performance and cost.

*** Amounts shown for each pond reflect projected cell sizes and free-standing pumps, pipelines and related hardware; design and permit costs are allocated on the basis of relative cell size, but the first full-scale application requires a disproportionately large share [savings on later applications should balance out total costs].

Exhibit D

TW Pilot: Water Characterization and NITREX Mini-Cell

Task 1: Develop a water sampling and chemistry analysis program to determine, on an annual basis, how much DIN mass is being carried in surface water discharging into Green Pond at the the Route 28 culvert, and carry out appropriate sampling and water chemistry analyses to make that determination with reasonably high levels of confidence. Subtasks could include:

Identify all water characteristics required to be measured, and the means and duration of measuring them, to obtain permits for a full scale surface intercept/treatment system

· Provide for peer review of the proposed sampling and chemistry analysis program and assure chain of custody control of samples taken and analyzed

· Identify variations in stream flow and corresponding water chemistry characteristics in order to help determine optimum processing capacity for the treatment cells

· Estimate the impact on stream flow variability and DIN mass resulting from periodic stream retention and release from the upstream cranberry bogs

· To protect the capability to re-establish fish runs, estimate the volume of stream flow and resulting DIN mass that would be diverted if a fish ladder were to be provided

· Furnish periodic progress reports so as to, among other things, allow the Town to decide about authorizing similar water characterization of Great, Bournes or other Ponds

In addition, it might be useful to consider some optional tasks for Green Pond that could be authorized, depending on results from the base project. Such optional tasks might be to:

· Propose an optional groundwater sampling plan if the Town decides to conduct such testing to identify potential nitrogen plume “hot spots” for potential interception

· Propose an optional plan to identify and screen potential DON removal concepts\

· Conduct water sampling to identify herbicides and pesticides in surface water discharges

Task 2: Develop a small-scale [van-mounted] NITREX substrate test program and carry out adequate cell testing to determine DIN removal capability as a basis for subsequent design of a full-scale system for surface discharges into Green Pond. Subtasks could include:

· Design and provide a test cell with associated equipment to operate and maintain it, identify the test site(s) and determine and obtain all necessary permits

· Identify all parameters to be tested and the duration thereof, together with the means of measuring and/or monitoring them, and supply appropriate hardware and software

· Provide progress reports on cell test results and any negative implications that arise

· Identify all water capture and discharge and related hydrogeological issues, and evaluate their potential impact on the viability of a surface water intercept and treat system

· Determine the impact of seasonal temperature changes on NITREX performance

· Identify and determine the impact of de-nitrification process kinetics; resolve any issues

· Determine final and average annual Nitrate levels in NITREX effluent

· Identify and determine the impact of likely modes of failure of the NITREX substrate

· Evaluate carbon loss, other life-limiting factors, associated with existing NITREX applications; identify and address any impediments to disposal of used NITREX media

Task 3: Based on results of Task 1 and 2, re-evaluate the DIN removal potential and estimated capital and operating costs for a full-scale system to treat surface discharges into Green Pond. In particular, the following questions must be addressed:

· How much DIN mass can be expected to be intercepted and removed on a annual basis?

· What should be the configuration of the NITREX cells [number and size], if located on Town-owned property, what are the optimum sites assuming eventual scale-up to treat the Coonamessett/Great Pond system, and what are estimated capital and operating costs?

· Identify all significant remaining issues/questions to be resolved before undertaking the design and construction of a full-scale Green Pond surface intercept/treat system