Recirculation Pumping Station

Recirculation Pumping Station

Front End Engineering Design

WGM’s Technical & Design team (T&D) were commissioned by Scottish Water to design a pumped Effluent Recirculation system to improve the existing treatment process at Galashiels STW in the Scottish borders.  Initial survey and investigation work determined the outline process requirements including a definition of flows and control philosophy, as well as potential pipework routes and pump location options.  Upon conclusion of optioneering workshops with the client, WGM was engaged to work up a detailed design proposal based on the preferred option.

Detailed Design – Civil, Mechanical, Electrical & ICA

The Client’s preference was to have an above-ground pumping station which provided a fixed rate of additional effluent to increase the wetting rate of 6 No. Percolating Filters.  WGM T&D carried out various hydraulic checks to determine the most suitable source of effluent including topographical and hydraulic level surveys, as well as drop tests in various chambers.  Having determined the most suitable chamber from which to draw flows, WGM T&D then carried out various calculations to determine the pumped system resistance curve, to permit the selection of a suitable pump and determination of power requirements.  Load scheduling and discrimination checks were carried out to ensure no issues with connecting into a local MCC.

Construction Phase

Construction design was completed and issued to WGM’s Construction teams.  Initial Civil works were undertaken to excavate the ground and install cable ducts, drawpits and buried pipework etc. prior to construction of the pumps base slab.  Pumps were installed on suitable plinths with suction and discharge pipework following on thereafter.  During construction, WGM’s T&D team were on site to monitor the build, resolve any technical queries (TQ’s), and witness various checks i.e. pressure testing and commissioning, along with the Client at times also.

Completion & Handover

Upon completion of successful commissioning, WGM T&D monitored the performance of the system for a two-week period of acceptance testing by the client.  In this time, flow and pressure checks were carried out to ensure the system was performing as per the Design.  Working closely with the client, WGM T&D were able to confirm that system was performing as expected and the anticipated process improvement was subsequently confirmed by the client.

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