SRA Annual Report 2020-21: Highways referrals and soil visits
In ‘Highways referrals’ SRA partners look for answers to highway flooding problems in better management of land nearby.
Cases generally involve Somerset County Council’s Highways Department and the Farming & Wildlife Advisory Group SouthWest (FWAG SW), with the former referring problems on to the latter. Highways officers may be told about matters by various sources – for example, residents or parish councils – or they may spot issues themselves, when they are out and about.
Highways referrals
Mendip
Chewton Mendip: Reports of slurry and muck spreading during heavy rain causing flooding and damage to highways, and run-off from maize ground. FWAG SW to visit.
Sedgemoor
Spaxton: Two FWAG SW advisers are investigating how silt and aggregates wash down from the upper catchment.
Somerset West and Taunton
A358 at Combe Florey: FWAG SW and Somerset County Council’s Highways Department have been working together to find ways of fixing problems with flooding along this stretch of busy road. One big factor is the surface water run-off from nearby steep fields, which fills the road’s drainage system with silt and then floods the road. In December 2020 a bank alongside the road got washed out. In the past, FWAG SW have visited the landowner and helped to set up a Countryside Stewardship agreement for planting grass and wildflowers which – when established – will help to stabilise the top soil and prevent some soil erosion. In 2021, the land management plans being discussed with the landowner are for a swale with silt traps at low points to slow the flow, with some water being away via cross-drains. In the SRA’s Enhanced Programme of works for 2021- 22, Somerset County Council’s Highways Department also won funding for major road drainage improvements.
Carhampton: Following reports from residents to Somerset County Council’s Flood Risk Management team of problems being caused by run-off from fields, a FWAG SW adviser made a soil husbandry visit to Court Place Farm, where possible mitigation options will be discussed.
Corfe: Somerset County Council’s Flood Risk Management team asked FWAG SW to assess reports of excessive volumes of water running off from a field close to the centre of the village. No evidence of soil erosion or gullying was found, but as residents say they have to put out sandbags regularly, and photos show notable amounts of water on the road, a follow-up site visit is planned with a Highways officer.
Kingston St Mary, Lodes Lane: Over the last 15 years, properties in Kingston St Mary have flooded at least 37 times because the drainage system coming down Lodes Lane could not cope with the volumes of water coming down from the Quantocks. The SRA’s 2020-21 Enhanced Programme of works gave Somerset County Council’s Highways Department funding for drainage improvements. The SRA also asked for field run-off to be looked at. Representatives from FWAG SW and the Highways Department duly walked Lodes Lane and found three areas showing obvious signs of field run-off. The aim is to reduce this.
Lower Holway: Two FWAG SW advisers walked along part of the Broughton Brook and a drainage ditch, following reports of flooding problems, and looked at some nearby fields. No land management problems were observed in the fields. However, it was recommended that the ditch should be cleared to ease the flow of water, that the Stoke Lane culvert junction should be de-silted and that an earth bank around a resident’s garden, and driveway sandbags, would hold water back.
Stogursey: Problems with field run-off referred by the parish council are being followed up by FWAG SW.
B3227 Wiveliscombe Road, Preston Bowyer: After the B3227 was blocked by a landslide caused by field run-off following heavy thunderstorms (see photo below), a FWAG SW adviser visited Joyces Farm to assess possible land management changes. To help slow run-off and stabilise the bank at the side of the road, the farmer planted a hedge, at his own expense. Working to a FWAG SW design, the farmer also installed a swale to help direct more water to an existing silt-trap. Over the winter, FWAG SW made a soil husbandry visit and discussions about soil management are ongoing.
West Bagborough: Continuing issues with run-off from steep tracks. FWAG SW held discussions with Somerset County Council’s Rights of Way section about one lane, along another track an adviser recommended surface-consolidation, cambering, flow spreaders and grips, and nearby cross-slope hedge bank creation.
Winsford, Furzehill Lane: The drainage system in this sunken lane was blocked with stones and soil, and FWAG SW were asked by Somerset County Council’s Highways Department to assess a partially-collapsed bank and the field above. An adviser found no problems with the soil-structure in the field, but did observe a spring filling a pond, which can overflow across the field towards the collapsed bank. FWAG SW recommended natural flood management works to buffer excess water and thereby reduce its velocity, also clearing the road drains.
South Somerset
Compton Dundon: FWAG SW visited a site where two agricultural buildings were being constructed, following reports of water running off from land onto a road, and farm vehicles pushing in ditches. FWAG SW wrote to the landholder about the requirement to install soakaways (a condition of getting planning permission for the buildings). The landholder agreed to re-surface a track so that it could be scraped to reduce the amount of mud getting onto the road. FWAG SW will revisit when it is raining.
Curry Rivel, Northwing Nursery: A natural flood management scheme was completed in summer 2020, after a painstaking process of investigation and collaboration that began with concerns expressed by a Curry Rivel parish councillor about heavy flows from fields down through Northwing Nursery and along Water Street down to Curry Rivel Primary School. For more information, see the entry for Curry Rivel in the section of this report about capital grant schemes for natural flood management.
Maperton, North Cheriton Road: Following reports of run-off causing problems on North Cheriton Road, FWAG SW advised alleviating severely compacted soil in the headland of a large arable field. The landowner responded promptly with subsoiling and mole ploughing (a kind of field-draining technique). FWAG SW also suggested to Somerset County Council’s South Somerset Area Highways Office that they should undertake roadside ditch clearance and cut grips in the verge to reduce the volumes of road surface water running down lane. Highways officers agreed.
Middle Chinnock, Poop Hill: At the request of Somerset County Council’s Highways Department, a FWAG SW adviser looked at different kinds of land use to see if any obvious factors could be spotted that might be contributing to run-off down Poop Hill and surface flooding in Middle Chinnock. Steeply sloping grassland was noted, along with a field that had recently been deeply ploughed and inverted close to hedges and trees. It was judged that this turning-over should improve the infiltration of water into the soil, although the Highways Department was advised that it would be worth keeping an eye out for possible problems with sediment.
Milborne Port, Oborne Road and Three Arch Bridge: FWAG SW to investigate whether land management changes could help to resolve a track flooding problem, referred by Network Rail via Somerset County Council’s Highways Department.
Misterton, Cathole Bridge Road: Reports from Misterton Parish Council via Somerset County Council’s Highways Department of severe run-off from a field. The Highways Department has jetted drains, but the road still floods. A FWAG SW adviser met a local highways officer on site, and together they found that soil was dense and compacted, although it had recently been cultivated and drilled. It was agreed that subsoiling should be suggested to the farmer, along with the creation of a scrape and bund in the corner of the field where water flows out.
Misterton, Station Road: Somerset County Council’s Highways Department was concerned about field run-off causing road and property flooding. One local resident, in particular, was affected, as their home is on a flow pathway. A FWAG SW adviser met this resident and had helpful discussions with the local farmer. The resident has now dug out a blind ditch with a small earth bank on the garden-field boundary.
Tintinhull to Montacute Road: Surface water runoff from fields was contributing to localised flooding. FWAG SW worked with local flood wardens co-ordinator Gordon Swindells, Somerset County Council’s Highways department, and the landowner and designed a scheme completed in March 2021. It including resurfacing the gateway entrance, and installing concrete slipways and headwalls to help protect underground culvert pipes and reduce the volumes of run-off reaching the road. For more information, see see the entry for the Tintinhull to Montacute road in the section of this report about capital grant schemes for natural flood management.
Soil visits
Better soil husbandry helps to reduce the run-off of surface water. Keeping soil in good health also brings obvious benefits to farmers.
The coronavirus pandemic limited opportunities for soil visits in 2020-21. Three were made, two as part of highways referrals – see Carhampton above and the B3227 Preston Bowyer landslip above.
Also:
Glebe Farm, Cheddon Fitzpaine: Blocked drains mean that a relief pipe is having to take all of the surface water from fields to the north of the village. This pipe cannot cope, causing flooding. The fields have been drilled with species-rich grassland, but a FWAG SW adviser found run-off was persisting down one headland. A series of swales and leaky ponds has been suggested as a way of reducing flood risks. Options are being considered.