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� :'P IV- <br /> MEMORANDUM <br /> February 15,2012 <br /> To Town of Mashpee Sewer Commission <br /> Project Watershed Nitrogen Management Plan <br /> From J.Jefferson Gregg,P.E. Tel.No. 774-470-1640 <br /> MEP Model Run Descriptions <br /> Subject (Options 1 A, 1 B,and 1 C) Job No. 8612001 <br /> The Town of Mashpee (Town) is undertaking a Watershed Nitrogen Management Plan (WNMP)to address <br /> nitrogen enrichment issues in the Town's estuaries. One management approach is to collect wastewater, <br /> treat it to a very high level, and then recharge the treated effluent back to the ground. The purpose of this <br /> memorandum is to summarize the three most recent approaches being developed on behalf of the Town for <br /> evaluation and modeling by the Massachusetts Estuaries,Project(MEP). That modeling effort is to identify <br /> whether the approach presented will achieve the TMDLs under a future condition. This memorandum <br /> describes the development and outline of these approaches that can then be crafted into alternatives for the <br /> Town to consider as part of the WNMP,following the results of the MEP modeling. <br /> Background <br /> In the Spring of 2008, as part of the WNMP, a Draft Alternatives Scenario Analysis and Site Evaluation <br /> Report was issued, and a "Draft NitrexTrm Technology Scenario Plan"was also prepared in order to evaluate <br /> five different scenarios for addressing future nitrogen loadings on the project Planning Area. <br /> These reports,with some update made to the NitrexTM approach, were then run through the MEP Modeling <br /> Approach to evaluate their ability to meet the TMDLs established for Popponesset Bay and Waquoit Bay <br /> East The results were issued in two memorandums dated November 13, 2009 and February 9, 2010. The <br /> results were compared to embayment thresholds and those Total Nitrogen (TN)thresholds associated with <br /> eelgrass and infauna. <br /> Following the release of those findings, the Sewer Commission then met to discuss possible discharge <br /> locations including those identified previously, such as Site 4 (the Transfer Station) and Site 7 (part of the <br /> New Seabury Golf Course), and new locations such as several parcels north of John's Pond (identified for <br /> presentation purposes as the Back Road Parcels), expansion of use at Willowbend Golf Course, and <br /> possible expansion of use at the New Seabury Golf Course. <br /> As a result of these initial MEP Scenario findings, the Sewer Commission had asked GHD to move.forward <br /> with the development of two new scenarios to be modeled at that time.The initial step of establishing these <br /> two new scenarios was based on a Sewer Commission map which re-divided the project planning area into <br /> several sections identifying preliminary collection and treatment locations within the project planning area. <br /> These groupings were similar to those established in the Draft Alternatives Scenario Analysis Report(called <br /> out as "sewersheds"); however, they were often larger and not necessarily based on potential collection <br /> system layouts but more often on neighborhoods/development areas.This preliminary figure(Figure 1:dated <br /> 12-13-10) shows each of these areas and their proposed discharge location. This preliminary layout plan <br /> GHD Inc.1545 lyannough Road Hyannis MA 02601 USA <br /> T 1 774 470 1630 F 1 774 470 1631 E hyamail@ghd.com W www.ghd.com <br />