LOW PRESSURE SEWER SYSTEM FOR AFFLUENT EXISTING NEIGHBORHOOD

The River Oaks subdivision is an affluent, mature residential community located in Fairfax, County Virginia which includes 114 existing single family dwelling units with individual septic tank drainfields. The Fairfax County Health Department determined that several drainfields have failed and expressed concern that others would soon fail. In order to prevent the health and environmental problems associated with failing drainfields, a wastewater collection system was needed to convey wastewater to the nearby County integrated sewer system. Numerous meetings were held with residents of River Oaks to plan and design a collection system with minimal impact to the existing community. Wherever feasible, existing homes were served by 8-inch sanitary sewers. Homes which could not be served by gravity sewers, were served by a low pressure sewer system including individual home grinder pumps and force main. The project included special provisions to minimize the impact to private property including directional drilling. The project consisted of the construction of 3,271 feet of 8-inch sanitary sewer, 900 feet of 8-inch water main, 12,175 feet of PVC force main in 1.25 inch through 3 inch sizes, 4,148 feet of 1.25 inch HDPE force main installed by directional drilling, 3,013 feet of HDPE force main installed by open cut construction, and 69 grinder pumps. Construction began in January 2007 at a cost of 6,048,000.