Sandwell Metropolitan Borough Council

Drainage Connectivity Survey to Reduce Flood Risk


  • Drainage | Gully


  • Surveying
The Problem

Understanding flood impact and water quality

An area of Sandwell has a storm water drainage system, and the Council needed to understand the potential impact of flooding to properties.

Thimblemill Brook on the boundary of the Abbey and Bristnall wards in Smethwick is fed by surrounding stormwater systems. In extreme weather, the stormwater networks become overwhelmed and water that would, under normal conditions, enter the brook had the potential to flood adjacent properties. Sandwell Council wanted to quantify that impact and get a better understanding of the water quality issues within it.

Our Approach

KaarbonTech undertook a large-scale drainage connectivity survey.

With Environment Agency funding, the Council commissioned KaarbonTech to undertake the project. Taking a staged approach, stage one looked at the condition of the drainage assets, the connections into Thimblemill Brook and the connections into the Severn Trent drainage network. The second stage used CCTV to perform an in-depth visual inspection of the problem locations discovered during the first phase so that any defects could be recorded, and recommendations for future work could be made. The final stage was to investigate and identify the cause of possible water pollution using ammonia testing at the outfalls of both incoming lines to the brook and conducting a CCTV survey of the connecting pipes upstream.

The Result

Drainage system assessed, improvements recommended

With a full inventory of the drainage system around Thimblemill Brook, recommendations for improvements were made for it to form part of the flood risk management plan.

During the first phase, we were able to inspect and record the condition of known drainage assets in the area and any new ones discovered during the process were plotted and the condition recorded. A small number of outfalls running parallel to the brook were recommended for dig-outs or jetting to reduce the risk of flooding issues in the area. The positive results of the ammonia testing led to a CCTV survey being conducted both up and downstream of the outfall, the likely source of pollution was located, and the Council was informed.


We are developing our flood risk management plan for extreme weather, making Sandwell greener and safer.

Councillor Ahmad Bostan, Sandwell Council,

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