23 April 2014

Costain has completed work on the refurbishment of Severn Trent Water (STW)’s Kineton waste water treatment plant near Coventry twelve months ahead of schedule.

The Kineton Q project involved revamping the site’s process assets to enable it to comply with lower EU ammonia discharge consent levels. These do not come into force until March 2015, however there was a small risk that the chosen solution might not deliver the required outputs to satisfy the new consent. The STW/Costain team decided to take a risk based approach and carry out the work as early as possible so it had time to react if the scheme was unsuccessful. In order to undertake the refurbishment work the process would have needed temporary treatment units to help prop up the site whilst the NSAF (Nitrifying Submerged Aeration Filter) was out of commission. However the team made use of the seasonal relaxation of consent levels for this site from November to April to undertake the work, so that no temporary treatment was required.

Explained Richard Price, Costain Programme Manager: “The Environment Agency relaxes consents for some sites in the winter when conditions are wetter and the concentration of ammonia in the waste is lower. In summer, conditions tend to be drier, the concentrations higher and so the consent is tighter.

“Carrying out the work in winter meant we did not have to install a temporary filter. Instead we just had to isolate the NSAF while we refurbished the plant’s media. This new approach allowed us to complete the physical works in less than a week, saving us a significant amount of time. Because the work was completed a year early we could also trial a lower cost option that did carry some risk of failure. We had the time to react if the solution did not work.”

By assisting the Severn Trent Water process engineers with sampling and testing, the Costain team was able to handover the process in less than two months.

Said Richard: “Close working with our programming team and the STW process engineers ensured a smooth and efficient handover. The assistance from Service Delivery in providing isolations was essential to completing the works as programmed, as was Asset Creation’s help in capitalising the scheme efficiently. I’m proud we were able to handover a full 12 months early.”

Sarah Greenhalgh, Severn Trent Solution Manager, Asset Creation Waste, South, commented: “Close co-operation was required with all parties to understand the risk of refurbishing the NSAF without providing alternative temporary process treatment. Thorough understanding of the risks together with a mitigation plan not only saved time but resulted in a significantly more economic solution.”

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