Galliford Try has been awarded a Thames Water contract worth in excess of £28m to upgrade Long Reach sewage works in Dartford.
The contract will be carried out in joint venture with Biwater and Mott MacDonald.
The contract is part of a £40m project at Long Reach to help clean up the River Thames, by providing additional treatment processes to improve the quality of treated effluent returned to the river.
The project includes the construction of aeration lanes, a final settlement tank, electricity substation, sludge storage building and blower house as well as modifications to existing facilities.
Construction is expected to start this spring, and is due for completion in 2012.