Deephams Sewage Treatment Works PHPS Upgrade Works

Deephams Sewage Treatment Works – PHPS Upgrade Works

End User

Tames Water

Client

Thames

Project Value

£1.5 Mil

Length of Contract

9 Months

Scope

Deephams STW powerhouse pumping station consisted of 6 DWF pumps and 4 storm pumps, the DWF pumps were motor and shaft driven Hydrostal pumps, 3 of the storm pumps are driven by diesel engines and the 4th is driven by an electric motor. The DWF pumps were earmarked to be replaced as they weren’t performing and were only delivery 700 l/s at 100% and regularly ragging up and requiring a lot of maintenance, All 10 double gated NRV valves were to be replaced with a single gate NRV valve as they were also ragging up and not closing properly as well as replacing all 10 air release valves too.

GEL Involvement

Gel Engineering took on the project as Principle Contractor and Principle Designer working closely with Thames Water to design and deliver the optimum solution for the pumping station. It was noted at an early stage of design that the existing monorail and pump gantry cranes were undersized for the new pumps which introduced another complexity to the project.

Gel Engineering had a full 3D model of the dry well completed to facilitate with the full design of the PHPS Gel Engineering then modeled the new location of the pumps, suction and discharge pipework, NRV & ARV valves and access steelwork.

Challenges experienced and how these have been resolved

Gel Engineering feeds on innovation and challenges, combined they result in magnificent project delivery. Deephams PHPS upgrade had many challenges some of which are outlined here:

Lifting Arrangements – The existing lifting arrangements were undersized for the new pumps; this included a monorail and 4 pump gantry cranes. New 5t monorail lifting beams and hangars were designed and installed along with chain hoists to allow for the maintainability of the pumps
Asbestos – It was noted in the Asbestos register that there were gaskets on the pipework, NRV and ARV valves that contained asbestos, Gel Engineering arranged & managed an approved asbestos removing contractor to safely remove all the gaskets and dispose of them accordingly
Constricted Areas – The dry well of the pumping station had very limited space to accommodate the removal of the existing pumps along with the old pipework, this required some innovative solutions to safely remove the redundant equipment. One such solution was the design & installation of a further gantry crane system to facilitate the removal of the pipework from the dry well
Isolations – The project had to be split into three stages to allow the pumping station to operate whilst the project progressed, this allowed for some careful planning to achieve double isolations on all the lines that were out of service and allow the other lines to operate. All isolations were the responsibility of the client although there were issues with achieving isolations on the reception chambers (outfall of the pumps) dam boards needed modifying and the amount of grit and silt in the chamber didn’t allow the chamber to be fully emptied. Gel Engineering stepped in and helped Thames water overcome these issues to allow the project to move forward at the required planned programme