Corbalis WTP Phase III Upgrade

Upgrades to the largest water treatment plant in the Commonwealth of Virginia.

Water Treatment Plant
Herndon, VA
Delivery Method
Fairfax County Water Authority
Year Complete

Project Overview

A $158.6 million upgrade of the existing facility increased treatment capacity from 150 to 225 mgd. The project featured a new 14-million-gallon underground clearwell, flocculation/sedimentation basin, chemical system, plate settlers, and the installation of an ozone system. Work also included the refurbishment of existing filters and an addition of a new filter structure; modification to the raw water structure and finish water pump station; a complete chemical system upgrade; and installation of a new 60-mgd raw water vertical turbine pump.

The project included the excavation of 500,000 cubic yards of material, placement of 60,000 cubic yards of concrete, nine miles of chemical piping and 100 process mechanical tie-ins.


  • ASCE Outstanding Civil Engineering Project of the Year Award


Gallon Underground Clearwell


Cubic Yards of Concrete Placed


Miles of Chemical Piping Installed