BH was selected to provide design, bidding, and construction phase services for a new 3.1 MGD water treatment plant (WTP) to serve the Borough of Gettysburg as well as two neighboring townships in Adams County. BH was responsible for all aspects of the project including process design, electrical and I&C, structural, architectural, HVAC, and site development. The WTP combines conventional water filtration technology with space-saving sludge blanket clarifiers and a computerized control system.
The WTP design consisted of intake bar screen, raw water pumping station, sedimentation by means of Infilco Degremont, Inc.’s Superpulsator technology, granular activated carbon filtration, chlorine disinfection, clearwell storage, finished water pumping station, powdered activated carbon feed system, alum feed system, and caustic feed system. The Superpulsator clarifiers integrate the functions of chemical addition, coagulation, flocculation, and solids separation. The design included a 50-foot gravity sludge thickener for filter backwash and sludge storage. The tank is covered with a fiberglass dome. The WTP was designed to be protected from a 500-year storm.
The WTP’s water source is Marsh Creek. The raw water can see rapid swings in raw water turbidity levels during storm events and seasonal high manganese concentrations.
A PADEP water supply permit application was prepared for the new facility. Additional permits included DEP General Permits 4 and 5 for the intakes and yard piping construction within a wetland. A Soil Erosion Control Plan and Land Development Plan were prepared for local government approval.
BH assisted in successfully securing funding from the Pennsylvania Infrastructure Investment Authority (PennVEST).
Following initial construction of the WTP, the Gettysburg Municipal Authority contracted with BH for additional services. To obtain an improved CT value for the clearwell at the facility, fiberglass baffles were designed for installation in the clearwell. Gettysburg Municipal Authority purchased and installed the baffles, and a tracer study performed by BH verified an improved baffling factor was obtained.
BH also assisted with the replacement of the underdrains and media in all three of the filters when the underdrains were found to be prematurely failing. The manufacturer provided new underdrains to correct the problem. Each filter was drained, the media removed, underdrain demolished, and then new underdrains were constructed and topped with new sand and granular activated carbon media.
BH also provided full-time resident inspection services during construction to oversee the three prime contracts. Construction was staged so the gravity thickener was built first, allowing for disposal of waste from the existing plant while the new plant was constructed over existing lagoons. BH provided start-up services and operations consultation in addition to writing the O&M manual.