The City of Bethlehem Wastewater Treatment Plant (WWTP) received approval from the Pennsylvania Department of Environmental Protection to abandon its Combined Sewer Outfall, CSO-004, to the Saucon Creek and replace it with CSO-12 to the Lehigh River, as part of the CSO Long Term Control Plan. Under heavy wet weather condition, the 45 MGD WWTP capacity was being exceeded, and the proposed CSO-12 would provide hydraulic relief to the WWTP.

Colliers Engineering & Design provided design services, water/wastewater engineering, permitting, and bid phase and construction phase services with its teaming partner, L.R. Kimball. The design scope included a new CSO below grade chamber (45’x 23’x 22’) to be constructed around the existing 66-inch interceptor sewer. The new CSO facility includes SCADA control, motorized sluice gates, solids screening, vortex siphon, and three 11,500 gpm, 70HP high flow pumps. The project also included new electrical service, a new emergency generator, site improvements, river encroachment permitting, and erosion and sediment control design and permitting.