Background
The London Borough of Merton (LBM) commissioned us to design a rain garden for their Raynes Park Bridge site.
The site area was located at a local low spot close to a railway bridge. Topographically it is located at the foot of Wimbledon Hill. As a consequence, the site is prone to flooding from surface water sources. The Council commissioned us to reduce this risk to properties and people around the area.
Process
Our flood and water management team supported the Council with:
- Identifying the exact location of the flooding
- Recognising how to direct surface water flows to a sustainable drainage system and how the drainage solution can reduce the flood risk
- Discussing with stakeholders what is required and identifying proposed solutions
- Producing a sustainable design with the introduction of planting for the rain garden, providing benefits to the amenity and biodiversity of the local area
Impact
The rain garden reduces discharge from the upstream area to an existing Thames Water sewer at an agreed rate of 2l/s. This is a significant improvement compared to the previous discharge rate of the modelled catchment, reducing flood risk in the immediate area as well as creating capacity in the sewer network.
The proposals also enhanced the attractiveness of the place, increasing planting and biodiversity. These natural features benefit the community living in the area while reducing the risk and impacts of flooding.
