Hydro-Brake® flow controls
A pioneering SuDS project on a Hampshire housing development, acclaimed as a national example of good practice, was made possible using Hydro-Brake® flow controls from Hydro International.
The 1900-home housing scheme by Persimmon Homes, at Elvetham Heath in Hampshire was developed over sandy soil, which offered some infiltration through soakaways at the top of the site, but none at the lower end.
To protect against surface water flooding, the Environment Agency required runoff rates from the impermeable surfaces of 2.72 litres per second per hectare, representing a 1 in 50 year event - a standard requirement at that time. In addition, the drainage solution needed to protect an area of the site designated as a nature reserve both during the construction phases and beyond.
Setting aside more land for large pond containment was not feasible so 18 Hydro-Brake® Flow Controls were supplied to provide balancing and buffering of the surface water runoff.
Smaller SuDS features protected with strategically located Hydro-Brake® Flow Controls were designed to attenuate the flow of surface water. In this way, the lower levels of the site and the discharge into the watercourse were not overloaded.
Ryan Lundy, senior civil engineer for Bradbrook Consulting worked on the design: “People see the numerous swales and large ponds when walking or driving around Elvetham Heath but probably don’t appreciate that many of them are interconnected. The strategically placed Hydro-Brake® Flow Controls provide balancing and buffering of the surface water runoff. Across the whole site the runoff is regulated by gravity and the storm water drainage strategy is achieved without the use of pump stations.”
The project is featured in the UK Government’s seminal Response to the Pitt Review, the forerunner of the Flood and Water Management Act.