Appendix 2-4 Copy of Needs Assessment Report, October 2007 • Comprehensive Wastewater Management Plan • Town of Falmouth, MA Little Pond, Great Pond, Green Pond, Bournes Pond, Eel Pond, and Waquoit Bay Watersheds Needs Assessment Report October 2007 Prepared for Town of Falmouth DPW COMPREHENSIVE WASTEWATER MANAGEMENT PLANNING PROJECT NEEDS ASSESSMENT REPORT TOWN OF FALMOUTH, MASSACHUSETTS Prepared for TOWN OF FALMOUTH, MASSACHUSETTS Prepared by STEARNS & WHELER, LLC Environmental Engineers and Scientists 1545 Iyannough Road Hyannis, Massachusetts 02601 August 2007 Project No. 7104510 EXECUTIVE SUMMARY COMPREHENSIVE WASTEWATER MANAGEMENT PLANNING PROJECT NEEDS ASSESSMENT REPORT TOWN OF FALMOUTH, MASSACHUSETTS BACKGROUND The Town of Falmouth (Town) is performing this Comprehensive Wastewater Management Planning (CWMP) Project to provide a comprehensive strategy for wastewater treatment and recharge of the treated water for the next 20 years and with consideration of buildout for the planning area. A primary goal of this Project is to build upon the past wastewater planning and nutrient management efforts to complement the work of the Massachusetts Estuaries Project (MEP) and allow efficient implementation of wastewater and nutrient management solutions. The main focus of the Project is to identify and prioritize sewer service areas for the Little Pond, Great Pond, Green Pond, Bournes Pond, Eel Pond and Waquoit Bay watersheds. These watersheds comprise the project planning area and are illustrated on Figure ES-1. The project planning area extends into the Towns of Mashpee, Sandwich, and Bourne. It also extends into the Massachusetts Military Reservation (MMR). Project team members are coordinating efforts with the other towns and the MMR. This CWMP Project is a major component of Falmouth’s town-wide effort to improve water quality, protect public health, and enhance the Town’s economic vitality by comprehensively managing its wastewater and other nutrient sources. The Project evaluates potential sites (Town- wide) to recharge the treated waters from the existing and/or new wastewater treatment facilities in Town. Other Town wastewater management efforts (outside this CWMP Project) include: • Implementation of sewers for the New Silver Beach area. • Upgrade of the existing Falmouth WWTF to an enhanced nitrogen removal facility. • Sewer connection of Falmouth High School. Town of Falmouth ES-1 Needs Assessment Report 7104510.2 • Completion of MEP evaluations for Little Pond; Great, Green, and Bournes Ponds; Quashmet River and Waquoit-East area; Oyster Pond; and West Falmouth Harbor. • Ongoing and planned MEP evaluations for Magansett Harbor, Rands Harbor, Fiddlers Cove, Silver Beach/Wild Harbor, Quissett Harbor, Salt Pond, Inner Harbor, and the western portion of the Waquoit Bay system. • Planned implementation of sewer service in the West Falmouth Harbor and Snug Harbor area. The Town has made significant progress on the Town-wide wastewater management components. This Needs Assessment Report completes the first of four phases of the CWMP Project. The Needs Assessment provides the framework and necessary background information to complete the second phase of the Project, where alternatives to remedy wastewater problems will be developed and evaluated (screened) for overall feasibility. The last two phases of the Project will consist of a public education/participation program, a detailed evaluation of feasible alternatives, a recommended plan of action, and draft and final Environmental Impact Reports in accordance with state requirements. The Needs Assessment Report utilizes existing information and future estimations of land use and water usage to project future wastewater flows and loadings for the design year 2030. Wastewater issues and specific problem areas of the planning area were identified and evaluated. Regulatory requirements and institutional considerations relating to wastewater management were incorporated into the evaluations. WASTEWATER PLANNING HISTORY Previous wastewater facility plans and environmental impact reports have recommended sewer extensions and wastewater system improvements in several portions of the planning areas, as listed below. 1. The 1981 Wastewater Facilities Plan recommended that portions of Falmouth Heights and the Maravista Peninsula be connected to the Falmouth Wastewater Treatment Facility Town of Falmouth ES-2 Needs Assessment Report 7104510.2 (WWTF) as a second phase of sewering in Falmouth. These areas (Phase II areas) were never sewered due to limitations at the Falmouth WWTF. 2. The 2001 Wastewater Facilities Plan recommended sewering in the West Falmouth Harbor watershed (west of Route 28 with a focus on the Snug Harbor area) to address water quality problems in West Falmouth Harbor. The 2001 Wastewater Facilities Plan also recommended sewering portions of North Davis Straits from Jones Road north to Maravista Avenue to connect several large wastewater generators and to address failing septic system problems in that area. These sewer extensions have not yet proceeded due to the unknown ultimate sewer system buildout in the Little Pond and Great Pond areas. The sizing of the sewers in the North Davis Straits area will be affected by additional adjoining area that may be sewered in the future. Also, the 2001 Wastewater Facilities Plan recommended improvements to the WWTF to expand treatment capacity and to improve the treatment quality for nitrogen removal. These improvements were completed in 2005. The 2001 Wastewater Facilities Plan also recommended sewer extension to the Falmouth High School (to be completed by the end of 2007) and a portion of Scranton Avenue. 3. The 2001 Ashumet Plume Nitrogen Offset Program recommended that engineered nitrogen mitigation efforts (sewers) be focused around Perch Pond and the middle portions of the watersheds to Great, Green, and Bournes Ponds. These recommendations have not proceeded. 4. Wastewater planning evaluations in 2003 developed sewer coverage options and a SewerCAD model for portions of the West Falmouth Harbor watershed and portions of Maravista Peninsula, Davis-Straits area, and the Little Pond watershed. The SewerCAD model of the Maravista, Davis-Straits, and Little Pond areas will be expanded and further developed to pick up potential sewer areas in the other portions of the planning area. 5. Several MEP technical reports have evaluated nitrogen limitations of the estuaries for the following planning area watersheds: a. Quashnet River, Hamblin Pond, and Jehu Pond in the Waquoit Bay system (Waquoit-East watershed). b. Great/Perch Pond, Green Pond, and Bournes Pond watersheds. Town of Falmouth ES-3 Needs Assessment Report 7104510.2 c. Little Pond watershed. The nitrogen limitations of these marine estuaries have been clearly identified in the technical reports and have been repeated in subsequent Massachusetts Department of Environmental Protection (MassDEP) reports on the total maximum daily loads (TMDLs) for these areas. The TMDLs (once approved by USEPA) will become the regulatory limit on the amount of nitrogen that can be discharged in the watersheds of these marine estuaries, and will be enforceable by the MassDEP. The technical reports and the TMDL reports indicate the marine waters have exceeded their nitrogen limits (and their nitrogen assimilative capacity), and significant amounts of nitrogen must be removed from the watersheds to attain nitrogen concentration threshold values established in the reports. One wastewater nitrogen removal scenario has been identified in each of the technical and TMDL reports to reach the threshold; and this suggested scenario has been used as the basis of the expected regulatory TMDLs. The suggested scenarios would require large percentages of wastewater nitrogen from the watersheds as indicated in Figure ES-2. This large level of wastewater nitrogen removal indicates the need for sewer extension in this area. FALMOUTH WASTEWATER TREATMENT FACILITY (WWTF) The Falmouth WWTF is located in West Falmouth off Blacksmith Shop Road east of Route 6. On average, it receives and treats 439,000 gallons per day (gpd) (0.44 mgd) of wastewater from the centralized collection system and 26,000 gpd (0.03 mgd) of septage from all of Falmouth. It utilizes a sequencing batch reactor and tertiary denitrification filtration treatment system, and effluent sand beds and spray irrigation fields for treated water recharge into the ground. This treatment system was completed in 2005 and replaced the previous aerated lagoon treatment system. The new treatment system has demonstrated its ability to produce a well-treated water with a total nitrogen concentration of 3 mg/L or less on average. The treated water is recharged to the groundwater at the WWTF and flows with the groundwater to West Falmouth Harbor and Buzzards Bay. Partial nitrogen attenuation occurs as the groundwater flows through wetland areas adjacent to Mashapaquit Creek. The MEP has recently completed a technical report for the West Falmouth Harbor watershed (West Falmouth Harbor MEP Report, 2006). This report and a subsequent TMDL report will be the basis of the future regulatory nitrogen limit for this estuary. The technical and TMDL reports are expected to be a Town of Falmouth ES-4 Needs Assessment Report 7104510.2 basis for a MassDEP effluent discharge permit being developed for the upgraded WWTF. The Town is currently awaiting the effluent discharge permit. CENTRALIZED WASTEWATER COLLECTION SYSTEM The centralized wastewater collection system