Massaponax WWTP, ENR Upgrade & Expansion Project

Spotsylvania County, Virginia

Project Description

This project included the installation of a second mechanical bar screen with screening washer/compactor, the construction of a second grit removal unit and installation of associated grit pumps in a new adjacent dry well. It also included the replacement of existing influent pump motors and impellers, hydraulic modifications to the existing bioreactor distribution box (raising rim), bioreactor modifications including the addition of a secondary anoxic zone, additional primary and secondary swing zones, and hydraulic modifications to baffle walls.

Southwood Builders also provided the construction of a new facility for storage and feed of supplemental carbon for denitrification, the addition of two (2) VFD controlled aeration blowers, additions of a third 1,717,976 gallon Precast Post-Tensioned Concrete secondary clarifier and associated scum pump station, and the addition of a fourth return activated sludge (RAS) pump. This include the retrofit of two existing sand effluent filters with cloth media, construction of provisional flocculant contact tank attached to a new effluent filer flow distribution box, installation of new ultraviolet disinfection banks 4A and 4B in existing concrete channels, modification of waste activated sludge (WAS) storage piping to allow grease feed to all (3) existing storage tanks, yard process piping and site utilities, site improvements, HVAC and plumbing system improvement, and electrical and instrumentation controls system improvements.

Electrical work consisted of the installation of a second mechanical bar screen, a second grit removal unit, replacement of existing influent pump motors, hydraulic modifications, Bioreactor modifications, VFD-controlled aeration blowers, the addition of a RAS pump, a new UV disinfection bank, modifications to the WAS storage piping, yard process piping, HVAC improvements, and other electrical / instrumentation improvements.

Project Details

Contract Value: $11,480,277

Completion Date: November 2012

Change Orders: $282,074 – Owner Requested Work

  • Job Completion 100% 100%

Additional Project Information


Key Personnel

Project Manager: Gene Campbell

Superintendent: Donnie Bryant


Work Performed by Southwood




Spotsylvania County

600 Hudgins Road

Fredericksburg, VA 22408



O’Brien and Gere

8401 Corporate Drive, Suite 400

Landover, MD 20785