SRA Annual Report 2018-19: Investigations (W1)
Every year Somerset Rivers Authority aims to fund a small number of investigations. The SRA looks particularly for issues that lie beyond the scope of what other individual organisations can do on their own – or for issues that fall between the gaps of what other organisations are doing – or for some combination of the two. As a co-ordinating body, the SRA can get different organisations working together as partners in ways they would do not otherwise.
A good example can be found in Moorland. This village close to the River Parrett is best known for being at the epicentre of the massive floods of 2013-14. But in recent years, heavy downpours in Moorland have also highlighted more localised problems with surface water drainage. Intense rain – more than 50mm in 24hrs – has caused internal flooding in at least one property along Northmoor Green Lane, the flooding of a small number of gardens and driveways along Church Road and resulted in standing water on roads.
On behalf of the SRA, the Parrett IDB and Somerset County Council have been working together to identify the causes of various problems. Their investigations have turned out to be extremely interesting. They have shown how developments over the last century have affected the extensive network of inter- connected ditches that used to exist along property boundaries and along the sides of roads and fields. Similar stories could almost certainly be told about other local villages.
Moorland’s old network of ditches has been impeded in numerous ways.
Watercourses often got culverted or filled-in when new homes and extensions were built, when parking spaces and driveways were created, and when gardens were enlarged.
Ditches that ran along both sides of roads have been extensively culverted and gully pots have been installed.
The network of small ditches that connects outfall pipes between properties to rhynes maintained by the IDB is in poor condition. Ditches are generally overgrown and clogged with silt; some have been filled-in or blocked with things like garden waste. A few ditches are difficult to access for maintenance due to the erection of sheds, garages and small agricultural buildings next to watercourses.
Very thorough analyses have been carried out for the SRA by the Parrett IDB and teams from Somerset County Council’s Highways Dept and Flood Risk Management section. Their work involved CCTV surveys, ditch de-silting, drain- jetting, vegetation clearance, consultation with residents and historical research.
These investigations led to proposals being drawn up for improvements. A bid was made to the SRA for funding as part of the SRA’s Enhanced Programme of works for 2019-20, and this was formally approved by the SRA Board in March 2019. A key part of the plan is to engage with local people – especially those who own ditches – about their future responsibilities for maintenance.
Chadmead ring bank
Not far from Moorland, in Chadmead, detailed topographic surveys have been carried out along the potential routes for a ring bank to encircle and protect properties. The background to this work is quite complicated. Summarising severely, Chadmead flooded badly in 2013-14. Water reached the highest depth ever recorded locally. Following consultations with residents about a possible ring bank, the SRA Board ordered further investigations. These have been led for the SRA by the Parrett IDB, with the SRA’s Community Resilience Officer helping to liaise with residents.
Research in 2018-19 has now established that a ring bank would need to be longer and higher than first anticipated, and include a section of concrete wall. The estimated cost would be at least £900,000 (not including land acquisition or compensation). Construction is expected to be difficult because of the need to work on soft peat. If material to build the bank could not be dug out locally, 20-tonne lorries would have to make around 1,000 trips back and forth along mostly narrow lanes.
Research has also indicated that if flooding on the scale of 2013- 14 were to re-occur, no homes would be flooded in the Chadmead area. This is because of the benefits of other moves taken locally, such as dredging, works at Beer Wall and the provision of additional pumping capacity.
In 2019-20, fresh discussions will be held with people around Chadmead before the matter returns to the SRA Board.
For other investigations, see the information about Tootle Bridge and Catsham in the River Brue Catchment section and Beckington in Resilient Infrastructure: Surveys and investigations (W4).