The Sewering of an Entire Town: How Chatham, Massachusetts is Planning to Gain Complete Control of Their Wastewater in order to Protect the Coastal Environment

The Sewering of an Entire Town: How Chatham, Massachusetts is Planning to Gain Complete Control of Their Wastewater in order to Protect the Coastal EnvironmentAbstractBACKGROUND The United States Environmental Protection Agency (USEPA) and Massachusetts Department of Environmental Protection (MassDEP) have recently implemented non-point-source, watershed-based nitrogen Total Maximum Daily Load (TMDL) limits for multiple small coastal estuaries around Cape Cod Massachusetts. The TMDLs for the four (4) estuarine systems around the Town of Chatham, Massachusetts, a town with a population of approximately 6500, are very stringent and require removal of much of the wastewater nitrogen coming from the many individual septic systems, as well as nitrogen from the stormwater and lawn fertilizers, at the many developed properties (see Figure 1). Nutrients have been overloading the local estuaries for years causing highly visible eutrophication issues as well as impacts to the groundwater-source drinking water supply. Based on these nitrogen TMDLs, the Town developed a Comprehensive Wastewater Management Plan (CWMP) which utilizes sewer extensions, a wastewater treatment facility upgrade, growth neutral land use controls, stormwater management, and fertilizer reduction research and management to meet the limits. THE PROBLEM AND ITS SOLUTION The Town has historically relied almost exclusively on individual septic systems for wastewater management. Once nitrogen was determined to be the nutrient of concern with respect to the local estuaries, sources of nitrogen were investigated. Almost 70% of the total nitrogen was identified as coming from wastewater and a full 85% of nitrogen from all controllable sources (fertilizers, stormwater, wastewater/septic system) was wastewater related (see Figures 1 and 2). Although many treatment systems were investigated including traditional and enhanced septic systems, cluster and decentralized systems and large-scale municipal wastewater facilities, it was the centralized treatment facility with its 93% removal of nitrogen that was needed to meet the strict TMDLs which required overall effluent levels to be at the limit of technology for nitrogen. In order to remove nitrogen to the extent shown in Figure 3, the Town has begun an extensive sewering project which will sewer two thirds of the Town in Phase 1 (which is expected to be complete within twenty years) and the balance of the town would be sewered in an additional ten years during Phase 2 as shown in Figure 4. In order to accommodate this additional wastewater, the water pollution control facility was upgraded significantly including nitrogen removal to 3 mg/L and accommodations for future phosphorus removal. The total cost of the extensive sewering and treatment upgrade project is projected to be approximately 300 million dollars with more than two thirds of those costs (210 million) being for the Phase 1. THE APPROACH The Town-wide approval of the plan was the result of a focus on outreach and public participation. This consisted of the creation of a citizens advisory committee (CAC) which contributed to the development of the CWMP. A key component of the plan that maintained the public's support was a 'Growth Neutral' bylaw which allowed for controlled 'wastewater related' growth within the Town. The involvement of the public through the CAC, public meetings, and other means was a primary reason why this CWMP gained approval where other town plans failed. In addition, the cost of the Plan was made affordable by spreading costs to all property owners, and by capturing scarce federal grants and taking full advantage of state and federal loan programs. IMPLEMENTATION As part of the Planning stage, an extensive Sewer CADD model of the entire Town was developed (results shown in Figure 4). This model included Phase 1 and Phase 2 of the CWMP implementation. The flat terrain in this coastal community resulted in the projection of over eighty pumping stations being needed for this small Town with a year-round population of only 6500. This model provided the roadmap needed to commence the Town-wide sewering project. In 2009, the initial implementation phase of this plan commenced with the 'backbone' of the collection system being designed and constructed. This 'backbone' consisted of the main gravity sewer lines and forcemains installed across the Town that will serve the vast majority of the expanded system. With both the backbone of the system and the wastewater treatment facility upgrade completed in 2012, a series of smaller collection system offshoots will commence in the ensuing years with the Town committing to a continuous sequence of small sewer extensions over the next few decades. As shown in Figure 5, the newly upgraded wastewater treatment facility has been removing nitrogen to the limit of technology since the initial startup was complete in the summer of 2012. SOCIAL, ECOMONIC, AND SUSTAINABLE DESIGN COMPONENTS This Project provided a roadmap for the Town to follow to solve problems created mostly by wastewater and provides the following social and economic benefits in Chatham: -A planning document outlining a wastewater solution -Remediation and protection of drinking, pond, and estuarine water quality -Preservation of the Town's fishing economy -Preservation of the Town's vacation economy -Land use growth protection (Flow Neutral) to apply to all properties connected to the sewer -Costs being distributed in an affordable manner. The historic use of septic systems as the primary type of wastewater management in Chatham was not sustainable because it was causing eutrophication of its coastal estuaries and freshwater ponds, and threatening its groundwater drinking water supplies. The CWMP recommendations of wastewater collection, advanced treatment, and treated-water recharge to the groundwater system provided a sustainable and holistic method for water resource management. Through the Town's efforts in completing their CWMP and growth neutral policy, they were also able to secure 0% SRF loans for this and their next phase of sewer extensions, over the 2% loans normally available. CURRENT STATUS The CWMP outlines a phased implementation of the Phase I sewering. With the initial implementation phase complete, the planning documents and SewerCADD models are now in use as the expansion of the collection system continues with annual sewering projects. The long-term plan to remediate the impaired waters is well underway as the Town has implemented its plan to gain complete control of their wastewater. This paper was presented at the WEF Collection Systems and Stormwater Conference, April 9-12, 2024. SpeakerDrainville, MarcPresentation time15: 45: 0016: 45: 00Session time15: 45: 0016: 45: 00SessionIntegrated PlanningSession number09Session locationConnecticut Convention Center, Hartford, ConnecticutTopicFlooding, Hydrology & Hydraulics, Machine Learning, Septic to Sewer, TMDLs, Water Quality, Watershed ManagementTopicFlooding, Hydrology & Hydraulics, Machine Learning, Septic to Sewer, TMDLs, Water Quality, Watershed ManagementAuthor (s) Drainville, MarcAuthor (s) M. Drainville1Author affiliation (s) GHD, Inc. 1SourceProceedings of the Water Environment FederationDocument typeConference PaperPublisherWater Environment FederationPrint publication date Apr 2024DOI10. 2175/193864718825159345Volume / Issue Content sourceCollection Systems and Stormwater ConferenceCopyright2024Word count26