Public Works and Environmental Services Alert:
The Fairfax County Department of Public Works and Environmental Services (DPWES) previously performed a condition assessment of the force main, which resulted in the need for two (2) external repairs which were performed in 2016. Due to its age, and as a result of findings during the assessment, it was determined the existing force main is nearing the end of its useful and practical life, and is in need of replacement.
A study was conducted to investigate options for replacing the existing force main. The location of the existing force main within a tidal creek and across residential properties, presents challenges for typical construction methods. Such challenges include: installation means and methods, staging and storage of materials, environmental regulations, potential time of year restrictions for site access, potential damage to the existing force main and adjacent utilities, impacts to private property, maintenance of traffic and accessibility to residences, and future operation and maintenance considerations.
After considering nine (9) potential alternatives, evaluated as part of a Basis of Design report, the selected alternative (shown in green below): minimizes environmental concerns, minimizes impacts to private properties, provides for potential nature trail improvements or amenities, and provides greater accessibility for future operation and maintenance efforts.
The existing 4,560 foot long force main, consisting of 30-inch diameter prestressed concrete cylinder pipe (PCCP) and ductile iron pipe (DIP), was constructed in the mid-1970s. It conveys wastewater pumped from the Little Hunting Creek Pump Station (located near the intersection of Thomas J. Stockton Parkway and Londonderry Road on the East side of Little Hunting Creek) which in turn collects wastewater from the surrounding community and from other upstream areas. The force main runs beneath Little Hunting Creek and through residential properties west of Little Hunting Creek, to a junction discharge chamber near the intersection of Surrey Drive and Surrey Court.
Located within the Mount Vernon District, the force main runs beneath Little Hunting Creek and through residential properties from the Little Hunting Creek Pump Station near the intersection of Thomas J. Stockton Parkway and Londonderry Road (to the east), to a junction discharge chamber near the intersection of Surrey Drive and Surrey Court (to the west). The project corridor is located across Sanitary Sewer Map Tiles 101-4, 102-3, 110-2 and 111-1, as shown below.
The project is currently expected to be advertised for construction bids in late March 2024.