Integral to the AMP 4 Quality Programme was the refurbishment and part re-construction of Esholt WwTW. The project’s underlying contract was tendered for with Morgan Sindall Group (“MSG”) who were awarded the works contract. As part of the overall scheme content MSG had to construct and commission a new Activated Sludge Plant.

The plant comprised of new aeration lanes and a distribution chamber, used to distribute mixed liquor flows from the aeration lanes to settlement tanks, which were proportionally split between newly constructed final settlement tanks and existing converted humus tanks.

Following construction and final commissioning of the pipeline, the transfer of flows from the distribution chamber to the converted humus tanks were found to be leaking. The route ran adjacent to the River Aire and there was a significant risk of polluting material entering the river.

In addition, the flow process needed to be maintained throughout any repair to ensure that YWS could continue to meet all of its final effluent compliance obligations. This meant that MSG had to establish a temporary pumping system capable of over-pumping flows between the ASP distribution chamber and the converted humus tanks.

Due to the volume and range of flow to be transferred, the temporary over-pumping system was a very costly exercise, increasing the pressure to make the repair and bring the system back into service as soon as possible.

PMP responded to an emergency request from MSG to attend site, assess the options to deal with the immediate problem and remove the risk of future occurrences.

The pipeline was constructed in 6m sections over a 300m distance, with each section “pushed” together and internally lined with a rubber seal at the point of connection. It was agreed that after the pipeline (1800mm Ø) had been drained, PMP were to enter and power wash the entire length prior to undertaking a condition survey.

Following the survey PMP were instructed to install AMEX-10 seals, not only on the identified leaking joint, but on all other pipe connection points, over 50 in total to secure the structural integrity of the pipeline.

Because AMEX-10 seals were used, PMP were able to significantly reduce the project time (and Yorkshire Water’s compliance and pollution risk exposure) as well as reducing the overall cost of remediating the problem when compared to the more traditional trenchless solutions.