EP was retained by the Duxbury Water Department in 2018 to develop a Water System Master Plan (WSMP). The purpose of this WSMP was to evaluate the Department’s water system with respect to water supply, treatment, demand, storage, and distribution. The recommendations presented in the report form a comprehensive water system plan through the year 2040. A significant focus of this effort was to evaluate alternatives for sequestering or treating various chemical constituents across the Department’s many groundwater sources.
Water System Assessment
The assessment consisted of an evaluation of the existing water system infrastructure, including water supply sources, distribution piping, storage tanks, and pumping stations.
EP prepared water demand projections and requirements through the year 2040 using US Census data and the most recent forecasting completed by the Massachusetts Department of Transportation. The projections were calculated following the Water Resources Commission (WRC) methodology, and compared demands using historic trends against demands using the MassDEP standard of 65 residential gallons per capita per day (RGPCD) and 10% Unaccounted for Water (UAW). This highlighted the magnitude of demand and UAW reductions required to maintain compliance with the Department’s MassDEP Water Management Act (WMA) permit through the planning horizon.
EP recommended the development of a Water Conservation Plan to identify the source of elevated demands and develop mitigation strategies consistent with the WMA permit.
Water Quality Study
EP reviewed the Department’s historic water quality data and conducted supplemental testing, which revealed elevated levels of iron and manganese at multiple wells, and elevated levels of PFAS at two wells.
EP prepared and analyzed simulated distribution system water quality samples to evaluate the effectiveness of various sequestrant doses at the affected well sites. EP ultimately recommended a combined WTP for two well sites, which would allow the decommissioned well site to resume operations while maintaining acceptable levels of metals in the combined effluent. EP also recommended improvements for PFAS mitigation at one well site.
Capital Improvements Plan Development
EP developed a phased Capital Improvements Plan (CIP) over the 2040 planning horizon. The CIP prioritized projects affecting critical supply sources, regulatory compliance, and fire flow availability in early phases. Later phases incorporate projects targeting system resiliency and risk preparedness, with the final phase focusing on a water main replacement schedule for mains that will be nearing the end of their projected service life. The draft report and CIP were presented to the Town Board of Commissioners for feedback in a public meeting.