- Mon Valley Sewage Authority
- Monessen and Donora, Pennsylvania
- Our Role
- Long-Term Control Planning, Surveying, Permitting, Design, Construction Management, Construction Observation.
- 10,000 LF of sanitary gravity sewer, 12,000 LF of sanitary force main, and a 3 mgal equalization tank
- Construction Cost
- $9 million
- New Construction
- 5 Years
Maximized flows to the WWTP and reduced the inflow and infiltration of wet weather into the Mon Valley Sewage Authority (Authority) system
Eliminated or minimized 17 combined sewer overflows (CSO) in the Authority's service area
Ensured that improvements and designs comply with federal CSO regulations.
Mon Valley Sewage Authority (Authority) worked with Gannett Fleming to implement the projects and recommendations of their combined sewer overflow (CSO) long-term control plan (LTCP) that the Pennsylvania Department of Environmental Protection approved in May 2008. The LTCP is intended to improve water quality for the community by limiting CSO.
The LTCP outlined three phases of work to be implemented during a 12-year period, with an estimated total project cost exceeding $50 million. Phase I construction comprises two stream separations, interceptor and force main upgrades, five pump station upgrades, and a 3.0-mgal equalization facility. Phases II and III comprise sewer separation and nine satellite treatment facilities.
Gannett Fleming completed design, surveying, permitting, and construction management services associated with the final design and construction of facilities for Phase I of the Authority's LTCP. The design of the equalization tank and WWTP upgrades was completed with Revit building information modeling (BIM) software. The fully functional, three-dimensional model includes all mechanical, electrical, and plumbing; structural; and architectural aspects of the facility.
Construction included approximately 10,000 LF of sanitary gravity sewer, 12,000 LF of sanitary force main, a 3 mgal equalization tank with a wet-weather pump station and valve vault, upgrades to the WWTP headworks including screening and grit removal, upgrades at 5 pump stations, manholes, restoration, and incidental work. Challenging aspects of the project included more than 1 mile of 16-inch, horizontal-directional-drilled force main adjacent to a highway in downtown Monessen, as well as multiple bores with diameters as large as 72 inches.
CSO LTCP development
Treatment facility design
Sewer separation design
Pump station and WWTP upgrades
Surveying and permitting.
More efficient pumps and variable-frequency drives included in the pump station upgrades reduce electrical usage
Increased flow to the WWTP improves water quality by reducing CSO volumes
Removal of streams from the combined sewer system reduces the clean water conveyed to the WWTP, reducing combined sewer overflow volumes and treatment costs
The equalization tank design included a reinforced grass driveway around the perimeter of the tank, which allows access to the tank while decreasing stormwater runoff.