Work Starts at Polperro for South West Water
Dean & Dyball Civil Engineering has secured a £5.5 million contract from South West Water for the design and construction of a sewage screening station, located in an isolated cove on the outskirts of Polperro, and a 330 metre long pumped sea outfall. The two stage contract process, which has now secured planning permission and for which construction work will commence on 15 June, began last August.
Polperro, a tiny fishing village approximately half way between Plymouth and St Austell, has limited vehicular access so the construction site of the screening station will be serviced solely by sea. To facilitate construction work a temporary steel working platform will be erected that will support a 100 tonne crane.
Mike Pickford, Regional Director of Dean & Dyball Civil Engineering, said: “We are looking forward to starting work on site and delivering this technically challenging and interesting project in line with South West Water’s expectations, bringing considerable benefit to the local community.”
Graham Murphy, South West Water’s Director of Engineering, added: “We are excited about work starting on the final phase of our Clean Sweep programme at Polperro. South West Water has invested £2 billion in the Clean Sweep programme, which has modernised sewage treatment all around the peninsula, removing almost 250 crude outfalls and transforming the quality of the region's bathing waters. The scheme at Polperro is one of the final pieces of the jigsaw.”
The screening building will be constructed from modular precast concrete sections. This system will be quick to erect, which will minimise construction time and risks to the programme from adverse weather conditions. Pre-fabrication will also give a factory quality finish and allow incorporation of a rock texture and colour matching that will help minimise the visual impact of the concrete structure in this Cornish beauty spot.
The 330 metre long outfall pipe will be constructed as a single section in Par Docks, with a concrete weight jacket being attached whilst the pipe is on land. Flotation pipes will then be strapped to the outfall pipeline to tow it into position, a distance of nine miles between Par Docks and Polperro. The pipe will then be sunk into a pre-excavated trench.
So that South West Water can maintain the facility, an access lift will be built from the coastal path to the screening building at the base of the cliff – 23 metres below. This will necessitate profiling of the cliff to a constant gradient, and a discreet system of rails will give a ‘shaftless’ design. When not in use the lift car will park inside the screening building thus achieving a visually discreet solution.
The project is set to complete in summer 2011.