CLEVEDON, U.K. - A FORWARD-looking sustainable drainage solution has helped make the development of 400 much-needed new homes on the South Coast economically viable by using infiltration basins and a wetland pond with Hydro's Stormbloc® to manage stormwater runoff.

With growing demand to meet the UK's ambitious new homes targets the Bryant Homes Southern Counties, George Wimpey South West Thames and David Wilson Homes development at Eden Park near Littlehampton, provides a national example of how a vision of sustainable drainage can solve the creation of additional impermeable surfaces when freeing up land for development.

As there were no public surface water sewers or watercourses in the vicinity of the site, a conventional solution to meet Environment Agency requirements would have involved costly works including a surface water pumping station and substantial storm sewer installations off-site. The alternative solution using Stormbloc® infiltration technology has delivered a much lower cost solution, and enabled low maintenance and easy access to the infiltration system once installed.

The installation is the outcome of a surface water disposal strategy and was developed for the site to meet Arun District Council's preference for a solution based on SuDS (Sustainable Drainage Systems) principles with maximum infiltration. First phase completion was due at the end of 2007.

Dean Frosoni of Consultants Cole Easdon said: "After investigating the soil and groundwater presence, we recommended providing three underground infiltration basins and a fourth incorporating open water with reeds to provide a total 3000cu.m storage volume. This would be sufficient to cope with total impermeable catchment area of access roads, roof, driveway and pavement covering an area of some 4.5 hectares.

"We recommended Hydro's Stormbloc® infiltration for its performance, value and lifetime costs after comparing four different systems. Stormbloc® is a modular system which provides a 95% void ratio with load bearing characteristics sufficient to permit pedestrian and vehicle loading above it. Stormbloc®'s accessibility channels and chambers for CCTV inspection and water jetting offered low maintenance over its 50-year design life.

"The solution has many cost benefits. By having four smaller basins we were able to maximise the available land for the developer and eliminate excessive invert depths required for long pipe runs. Basin excavations could be kept shallow with cost and Health and Safety benefits as well as ease of access for future maintenance."

"A further factor was that EA (Hampshire) had recently approved the use of Stormbloc® for complementary flood storage at a development at nearby Lymington.

Client: Bryant Homes Southern Counties , George Wimpey South West Thames and David Wilson Homes
Consultant Engineer: Cole Easdon Consultants
Installation Contractor: Aeropark

If you would like any further information on the Hydro Stormbloc®, or any of Hydro International's stormwater, wastewater and sewage treatment systems, please call 0800 269371.