H.L. Mooney WRF Expansion and Upgrade Stage 2

State-of-the-art nutrient removal to meet Chesapeake Bay Watershed regulations.

Treatment Plant
Woodbridge, VA
Delivery Method
Prince William County Service Authority
Year Complete

Project Overview

This $118.8 million design-build expansion of the existing facility increased capacity from 18 mgd to 24 mgd and provided state-of-the-art nutrient removal to meet Chesapeake Bay Watershed regulations.

Work included new screening and grit facilities, primary clarifier, aeration basin and secondary clarifiers; reconfiguration of existing and installation of new aeration basins; a new influent and RAS pump station, thickener sludge pump station, denitrification facilities, gravity thickeners and centrifuge dewatering system; installation of 14 400-square-foot gravity sand filters; construction of a new six-chemical feed system; and a new plant-wide SCADA system.

The entire process flow was intercepted and routed incrementally with no permit violations and zero impact to discharge effluent quality.


  • 2011 DBIA Design-Build Excellence Award


Total Design-Build Project Value


400-Square-Foot Gravity Sand Filters


VFD Driven Feed Pumps for Polymer System

Our Clients

Having worked with PC for well over a decade, I can say that this very successful project exemplifies what we have come to expect. The success of this project can be strongly tied to the people PC has had managing this project as well as the participative and professional manner in which they accomplish their work.

Charles Weber

Director, Engineering & Water Reclamation • Prince William County Service Authority