The Western Westmoreland Municipal Authority (WWMA) is constructing major sewer system improvements to eliminate wastewater discharges into the Brush Creek during wet weather events, as per a Consent Order and Agreement (COA) with the Pennsylvania Department of Environmental Protection. To support implementation of the COA improvements project, Wade Trim developed a permanent flow monitoring program for the interceptor system and provided hydraulic model development, model calibration, alternative development, cost estimates and alternative evaluation. The preferred alternative advanced through design and permitting includes replacement of 7 miles of interceptor and construction of a 7-MG equalization basin near the Brush Creek Wastewater Treatment Plant (WWTP). A 45-MGD influent pump station is also required to pump wet weather flow into the equalization basin due to the local topography and geology.
The interceptor will be upsized from 8- to 33-inch-diameter to 12- to 48-inch-diameter pipe. Constructability was a major concern as the existing interceptor runs along Brush Creek and Bushy Run with major sections either in the toe of the stream bank or in the stream itself. The design also accommodates three miles of asbestos cement pipe (ACP); a parallel system will be used so that the existing ACP interceptor can be removed from service and left in place. The equalization basin is an above ground wire- and strand-wound, circular, prestressed concrete tank located on a hill adjacent to the WWTP. In addition, WWTP upgrades will be made to improve hydraulic performance and operations.
Due to the size and complexity of the project, construction is phased over four years. The equalization basin, pump station and WWTP improvements are currently under way with interceptor construction scheduled to begin this fall. The entire COA improvements project is required to be complete by May 2020.