A massive review of drainage systems across Somerset has been carried out for Somerset Rivers Authority, as part of a plan to reduce flood risks and make places better to live, work and visit.
Twenty recently-built sites were inspected. These included big housing estates (such as one at Creech St Michael, pictured above), retirement apartments, industrial units and offices, an arts centre, and a hotel and pub.
The survey was done for Somerset Rivers Authority by Somerset County Council’s Flood Risk Management Team, working with Wessex Water and contractors JBA Consulting. Together, they assessed 438 elements of the selected sites’ Sustainable Urban Drainage Systems – known for short as SuDs.
SuDs aspire not just to control and reduce flows of water, but to improve water quality and to make places greener and pleasanter for people and wildlife. This can be achieved through using natural measures such as streams, ponds and reed beds and techniques such as rainwater harvesting, permeable paving and tree-planting.
Cllr John Osman, Chairman of Somerset Rivers Authority (SRA), said: “This review of developers’ SuDs’ schemes is a unique and impressive piece of work, that’s only happened because Somerset has the SRA.
“We’ve funded it because we know that people do worry about the run-off of water from new developments. So we wanted to see how SuDs are working.
“Are they being built as designed? Are they being maintained? Are developers achieving as much as they could? Those are the kind of questions we wanted to investigate.
“We’ve found that there are good examples of SuDS in Somerset – but there are also areas where the SRA and its partners can work with developers to try and achieve more.
“We are now aiming for improvements across Somerset.”
To help achieve this, the study’s findings are being shared locally and nationally in a 747-page report. (Download a PDF summary: Somerset-Rivers-Authority-SuDS-review-summary)
Further SRA-funded initiatives, being led by Somerset County Council, include:
- producing a Somerset-specific guide to SuDS
- providing inspectors to visit developments while they are being built
- creating showcase sites to demonstrate how many benefits can be won through designing, implementing and maintaining more ambitious schemes
As things stand, the review found little evidence of provisions for wildlife or public amenity being built into drainage designs, and very little evidence of explicit consideration of water quality, although several sites included features that would improve water quality.
Inspections at some developments still being built showed poor site management practices, allowing sediment and pollution to enter surface waters.
Individual defects were also identified, such as poorly-constructed permeable paving, non-native vegetation, and road and car park levels being higher than the entrances to properties, thereby raising the risk of water flowing down into them.
Of all the assets inspected, 60% were in good or very good condition, but 6% were poor or very poor. In poor cases, little was known about who was responsible for maintenance or what the maintenance regime should be.
Cllr David Hall, Somerset County Council Cabinet member with responsibility for flood risk management, and the council’s representative on the Board of the SRA, said: “This SRA-funded project has given us a huge amount of valuable evidence. It will help us all to achieve better ways of managing surface water in new developments. It will also help us to realise the full potential of wider initiatives like Taunton Garden Town. And it will be of interest nationally, because issues with SuDs are not confined to Somerset.
“We will all benefit from this. The people of Somerset will get greater protection against flooding and better places to live, work and visit, and developers will get useful and realistic guidance that helps them to build properties that people want to buy and rent. It’s a win-win.”