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 jbarnes@capecod.net, 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, jhall@mounthope.net

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, swhite@paragonenv.com

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, info@tighebond.com

Capella Consulting Group, Dr. R Jude Wilber, President; and ECO/NH, Mr. William Eustis, President; jwilber@capecod.net

Geo-Con; Brian H Jasperse, President, 4075 Monroeville Blvd., #400; Monroeville, PA 15146; 412.856.7700; www.geocon.net, bjasperse@geocon.net

J.W. Salm Engineering Inc; John W Salm III, 12432 Collins RD, Bishopville, MD 21813; 410.213.0805, f410.213.0848; www.jwse.com, jsalm@beachin.net

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

Waterflow Consultants Inc; John D Eppich, 1506 Alma Dr, Champaign, IL 61820; 217.352.4549; f217.352.4474;www.waterflowconsultants.com, deppich@waterflowconsultants.com

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, swgroup@uswest.net Or try mogden@swg-inc.com

Teal Ltd., Susan Peterson, PhD and Partner; 567 New Bedford Road, Rochester, MA 02770; 508.763.2390 or 508.972.1689; sbptrsn@ma.ultranet.com

CME Associates, Inc; Machael G Shaefer, Director; PO Box 149, Woodstock, CT 06281; www.cmeengineering.com; mschaefer@cmeengineering.com

Massachusetts Institute of Technology; Heidi M Nepf, Associate Professor of Civil & Environmental Engineering; 617.253.4322; hmnept@mit.edu

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; owencr@fpc.edu

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 wetland@cape.com with a copy to jbarnes@capecod.net. 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:

FAPCC’s Investigation of Treatment Wetlands Technology

Exhibit A-1

Attachment to Exhibit A-2

Exhibit A-3

Constructed Wetlands (CW) Science Subcommittee Report