The package forms part of Thames Water’s wider programme to upgrade more than 250 sewage treatment and sewer sites between 2025 and 2030.
Costain will divide the work between eastern and western regions, with each area led by a regional senior project manager.
The eastern programme will cover sites at Barkway, Brentwood, Long Reach, Little Hallingbury, North Weald and Standon.
The western programme includes Aldershot, Burghfield, Esher, Horley, Lightwater, Marlborough, Northleach, Waddesdon and Windsor.
The work will involve modernising inlet stations, improving the resilience of storm tanks and carrying out repairs, modifications and upgrades across wastewater systems.
Costain water sector director Matt Bateman said: “We’ll work closely with Thames Water and our supply chain partners to deliver these essential infrastructure upgrades, that will build resilience into the region’s critical wastewater system, efficiently and safely.”
Costain has previously delivered treatment asset upgrades for Thames Water at Markyate, Brickendon, Sandhurst and Selborne.
The contractor is also carrying out clay compaction trials for Thames Water’s planned White Horse Reservoir project in Oxfordshire.
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