A Costain team working on the Severn Trent Water (STW) AMP5 framework has devised a way to shutdown an entire sewage treatment works without using storm facilities.

The team developed and trialled the strategy when installing a new inlet works with associated screens and handling at the Stratford Milcote sewage treatment works.

As Tom Grainger-White, Costain Senior Site Agent, explained, the strategy reduces risk and saves money:

“Traditionally when a treatment works is shut down, foul water is transferred to tankers and then transported to other sites. By compiling information such as how wastewater flowed between the 15 pump stations that fed the site, and carrying out tests to check those interactions, we were able to turn off individual stations. This allowed us to increase the time we could turn off the main treatment works, and so no tankers were required.”

The strategy proved its worth when a faulty valve was discovered at the Paddock Lane pump station near the centre of Stratford-upon-Avon.

Tom Grainger-White continued:

“This was an urgent situation for our client.  Paddock Lane is a very large pumping station, it’s in a residential area and is almost impossible to tanker from. But the three trials we carried out at the Stratford Milcote scheme were enough to convince everyone that STW could perform shutdowns further up the network and so safely replace the valve.”

Mick Jones, STW Service Delivery Manager for Stratford explained:

“We had carried out full shutdowns on Costain’s scheme at Stratford Milcote, but not at Paddock Lane and not for this type of work. My team and senior management needed reassurance that the work already undertaken could be applied to this situation. So we asked Costain to provide us with details of previous shutdown trials to assess if we could run a similar operation.”

Using the information gathered at Milcote, the team was able to safely replace the faulty valve the next day. STW estimated the work cost around £35,000 less than if overpumping had been required.