Prior to allowing our Wincoram Commons client to connect to SCSD #11, SCDPW required assessment of the capacity of the existing downstream collection system in the Selden Sewer District to ensure it had capacity for the additional flow. This involved an assessment of both our client’s flows as well as several other developers that had proposals to connect into the District system. Our analysis showed that the existing District sewer system had marginal capacity for the additional flow, as did the existing District force main, but the existing pumping station required replacement with a new, larger pumping station. A joint venture of private owners was formed and HE was retained to perform the engineering services for the preliminary design report, final design plans and specifications, and construction administration services. The new pumping stations features a 35’ deep cast-in-place concrete wet well with an influent grinder, two (2) 560 gpm submersible pumps, valve chamber, flow meter pit, and a precast concrete control building with emergency generator. The average daily design flow is about 150,000 gpd, which includes the flow from Wincoram Commons as well as Island Green, Selden Plaza, All American Assisted Living (another Hayduk Engineering project), and a large segment of existing single family homes serviced by the SCSD #11 system. The design and construction was complicated by the presence of poorly drained soils, high groundwater table, a constricted site with “work-around” environment, and the necessity for significant steel sheeting and bracing and dewatering. The pumping station has been operational since 2015.
This project was awarded the 2017 Long Island Builders Institute Gold Award for Engineering Design.