P7 – Western Mill Substation


Project: Flood Defence Measures
Location: Western Mill Substation, Plymouth
Client: Western Power Distribution
Role: Principal Contractor
Duration: 15 weeks

The bespoke flood defence project involved protecting the switch house building and the outdoor switchgear on the primary substation site. The design of the flood defences had to guard against a predicted 1 in 100 year flood event of 1.6m above the switch house floor level. The work involved excavating, by hand, to foundation level; sealing letterbox cable entries and ducts using CSD RISE products (for which we are approved installers) and external tanking using the Bituthene 8000 system with a protective skin in facing brickwork, capped with plinth stretcher special bricks. Extreme care was necessary, as some highly sensitive lead-cored cables exited the switch house – which also contained a live open fuse board.

Bund walling with integral tanking and floodgates was installed, together with some deep drainage within the external access road. A bespoke non-return valve was specifically sourced by Grant Construction. This was remedially fitted to a 450mm diameter deep storm water drain, expelling to the nearby watercourse.

All substation equipment remained live during the project. Despite the obvious dangers, all necessary work was completed without incident.