Challenge

The Blackburn Brook runs through a 500m long culvert beneath theThorncliffe Industrial Estate. The small existing weir, situated on the brook, creates a holding capacity of just 4000 cu.m; this was not large enough to provide protection from flooding. As a result, the industrial estate and nearby housing suffered flood damage and disruption.

Solution

To alleviate this, a dam creating a potential storage capacity of 32,000 cu.m has been constructed approximately 300m upstream from the culvert near Devil’s Bridge, on the Blackburn Brook just outside Sheffield.

JBA Consulting specified the project was to include two 1098mm diameter Hydro-Brake® Flow Controls to restrict the flow to a design maximum of 5.7 cu.m/sec, protecting the culvert.

Outcome

João Santa-Clara, Consulting Engineer, JBA Consulting, commented: “The area suffered from extensive flooding in 2007, due to a 150-year storm event which exceeded the capacity of a culvert on the local Blackburn Brook. The flood caused a great deal of damage and a dam was needed to prevent a repeat.

“By installing two 1098mm diameter Hydro-Brake® Flow Control devices we can control the water flow to match the maximum capacity of the culvert, without the stored water taking excessive land in a restricted area and country park.”

Alex Stephenson, Stormwater Division Director, Hydro International, added: “The Hydro-Brake® Flow Control installation will control the flow, up to a design maximum of 5.7 cu.m/sec, so will protect the culvert and prevent overtopping.

“Above this flow, the stored water will back up behind the dam but the flow characteristic of the devices limits the speed of back-up compared to other forms of flow control, saving in the region of 10-15% of land grab.”