Filter Backwash Storage Design for Western Branch WRRF

Team: Team WEF

Program: Environmental Health and Engineering

The Western Branch Water Resources Recovery Facility (WRRF), which is designed to treat 30 million gallons of wastewater each day, faces disproportionately high flows because of precipitation and groundwater inflow and infiltration into the vast network of pipes that bring wastewater to the plant. WSSC Water, the owner and operator of Western Branch WRRF, presented concerns about potential violations of the strict nitrogen and phosphorus limits set by the State of Maryland to this design team and tasked the team with mitigation of the problem. The proposed solution targets the dirty backwash water produced by the 11 anthracite filters, which are currently bypassed during periods of high flows. The proposed design is a 3-million-gallon backwash storage tank, which can hold the dirty backwash during high flow periods to allow the filters to continue to operate. This preliminary design report includes the justification and design of the backwash storage tank, hydraulics, and solids handling, in addition to a cost estimation and preliminary project schedule.