Managing highway surface water runoff as part of a much-needed development of affordable housing in rural Cornwall, UK has been assured with a Stormbloc geocellular soakaway system from Hydro International.
Maintenance and regular inspection were key considerations in a Sustainable Drainage System (SuDS) that required two soakaways to be built to manage surface water from Bassett Road as part of Coastline Housing’s 49-home development in the village of North Country near Redruth.
As the ground conditions in Cornwall are usually favourable for infiltration of excess surface water, Cornwall Council promotes the use of soakaways as the preferred option for surface water drainage in the county.
Consultant Engineers Nijhuis H2OK Ltd specified Stormbloc with a Stormbloc Inspect system to ensure regular inspection and maintenance of the soakaways and comply with local authority highways and drainage guidance with a view to adoption by the council.
Stormbloc Inspect’s inspection chambers and access tunnels in the soakaways are fully integrated within the modular block system to ensure simple installation and connection to the surface water drainage system, as well as easy access for ongoing maintenance.
“Percolation testing carried out to CIRIA156/BRA 356 indicated that the ground had good drainage characteristics,” confirmed Jan Clark, Development Infrastructure Manager for Nijhuis H2OK.
“We specified Hydro International Stormbloc units as they have been successfully adopted by Cornwall Council on other projects. The council are keen to incorporate improved access and inspection facilities on all drainage features and the Stormbloc inspection facility helps in this regard.”
Surface water is drained from a total 1,500 m2 stretch of highway through road gullies and a gravity pipe system to the two soakaways. Both 1.98 m deep, the soakaways measure 10.4 m x 7.2 m and 9.6 m x 4.0 m and are each situated under separate soft landscaped areas.
The Bassett Road soakaway system is designed to protect the highway from a 1 in 100 year flood event and includes a 30% climate change allowance. Stormbloc Inspect can be installed under landscaping or even roadways, while remaining easy to access for inspection and maintenance.
The North Country development was built for Coastline Housing, a local not-for-profit housing association that owns and manages over 4,000 homes in the county. The first phase of the development was finished in March 2016, with a second phase completed in the Summer.
With house prices in Cornwall continuing to be more than 11 times average earnings, many people have been excluded from owning their own homes. The North Country development is one of the housing association’s biggest-ever developments, providing homes for rent, part-buy and part-rent, and is supported by Homes and Community Agency funding.
