SRA End of Year Report 2017-18: Resilient Infrastructure (W4)
A38 drainage improvements
The A38 is one of Somerset’s busiest roads, giving access to and from Taunton and Wellington, and carrying over 17,000 vehicles a day. It is the emergency diversion route if the M5 is closed. SRA funding will help to reduce flooding along two strategically important sections.
1) A38 Rumwell: Flooding at Rumwell frequently affected half the carriageway. Sometimes the whole road would be submerged, with gridlock very quickly resulting. The problem was a drainage system that was over 90 years old and could not cope.
Achieved: A new drainage system has been installed. The work was delivered for the SRA by Somerset County Council’s Highways Department using contractors Skanska, and Bridgwater-based sub-contractors P Phillips & Sons.
2) A38 Chelston: Investigation and feasibility works have been undertaken by Somerset County Council’s Highways Dept for the SRA.
Not yet achieved: A scheme is scheduled to be designed and carried out in 2018-19, to complement the works at Rumwell.
East Stoke, Stoke sub Hamdon flood alleviation
A scheme to help prevent the flooding of 10 properties at East Stoke and the road between Stoke sub Hamdon and Montacute (near Yeovil). Improving a culverted watercourse will enable the better capture, storage and removal of surface water runoff.
This scheme is being delivered for the SRA by Somerset County Council.
Being achieved: The council’s contractors Skanska began a CCTV survey, but could not complete it because of a large blockage which needed to be investigated further. Two manholes were put in to give better access and a full CCTV survey was then done. Its results are awaited.
Residents will be told what was found and what further actions are required for a successful scheme to be designed and built.
A372 Pibsbury Corner, Huish Episcopi
The A372 is a strategically important part of Somerset’s principal network, used by around 8,000 vehicles a day. Half the carriageway was regularly flooded, causing safety problems as vehicles negotiated their way round a blind corner. Flooding also affected four properties and hampered access to the popular Huish Episcopi allotments site. Achieved: The main aim of the works was to intercept and re-direct water before it caused problems down at Pibsbury Corner. More than 135 metres of new drainage pipes were therefore installed, along with several new gullies. Three new headwalls were built to secure pipes where water flows out into ditches. Sections of ditch were cleared. The A372 carriageway and footway were also re-profiled to remove the low point where water flooded the inside of the bend.
The works were delivered for Somerset Rivers Authority by Somerset County Council’s Highways Dept using contractors Skanska and Bridgwater-based sub-contractors P Phillips & Sons.
Lower Bilbrook Lane
Improving drainage along Lower Bilbrook Lane will stop around 10 residents in the West Somerset hamlet of Bilbrook from being cut off and preserve access for other road users. This SRA-funded scheme is additional to an earlier Somerset County Council project that helped to collect water from the small watercourse that joins into the highway system along Lower Bilbrook Lane. This new scheme is supported by the parish council. Being achieved: Investigation, feasibility and initial design works have been undertaken by Somerset County Council’s Highways Dept, on behalf of the SRA. Work is due to be carried out in summer 2018.
Flood alert systems
Proposed installation of sophisticated new flood detection and warning systems that provide real-time information, to help generate and broadcast warnings and reduce the risk of people getting injured and vehicles damaged, particularly when it is dark. Carried forward from 2016-17. Not yet achieved: Three sites have been selected by Somerset County Council’s Highways Dept for the SRA – A359 Yeovil to Sparkford Road near Mudford; A378 Langport Road, Wrantage; Oake Road, Bradford on Tone. In October 2017, the SRA Board agreed to increase the amount of funding available for these flood alert systems and to provide an annual sum for their maintenance. Since then, following a re-evaluation of the proposed supplier’s charges, the Highways Dept is undertaking a procurement exercise to be sure of obtaining best value for money.
Inspections and remedial works to culverts under roads in IDB areas
A long and ongoing project to investigate and improve more than 700 of the most vulnerable and strategically important culverts within Somerset Internal Drainage Board (IDB) areas.
It has not always been clear who is responsible for these structures. SRA funding was therefore given for two reasons: firstly, to gain a better understanding of all these culverts; secondly, to improve them, regardless of who owns them.
Activities such as removing blockages, and replacing structures which are broken beyond repair, will improve the conveyance of water and will help to prevent disruption to residents and road users.
Being achieved: A comprehensive database has been prepared, identifying more than 700 culverts beneath roads in IDB areas. The culverts’ condition has been assessed and work schedules prepared for improvements at the highest priority sites. De-silting, vegetation clearance, high-pressure water jetting and structural repairs have begun.
One early site was Northwick Road near Mark. Along quite a stretch of the south side of this road runs Northwick Rhyne (pictured below): on the north side are non-viewed rhynes (which do not get the same IDB maintenance as Viewed Rhynes). The problem here was that water from the non-viewed rhynes was topping over Northwick Road into Northwick Rhyne and threatening to flood a house nearby. The IDB cleared a small culvert that had been found blocked-up. Water levels dropped within minutes and by next morning were back to normal.
Other early sites have included Glastonbury Bypass and roads nearby, and Park Rhyne which crosses Tucker’s Lane between Baltonsborough, Butleigh and Street.
Funding for this enhanced flood risk management work began in 2016-17. It will continue in 2018-19.
Somerset County Council’s existing budgets only allow for the de-silting of structures such as bridges when there is a threat to the structure itself. Extra SRA funding enables de-silting where there is also a benefit to the watercourse and, therefore, a reduced risk of flooding to roads and nearby properties.
Achieved: De-silting of structures was completed in Mendip at Dean, beneath the A361 near Shepton Mallet, on a watercourse close to the Methodist Chapel and not far from two reservoirs; Ford House in Ford, between Chewton Mendip and Litton, on the River Chew beneath the B3114; near Witham Friary, close to Witham Hall Farm on a tributary of the River Frome: in Taunton Deane – Ash Mill Stream at Ash Farm on a tributary of the River Tone between Chelston and East Nynehead; Theats Farm, Creech Heathfield Road, Creech Heathfield, on a tributary of the River Tone; Ford South in Ford near Wiveliscombe, on a tributary of Hillfarance Brook, beneath the B3188; Stoke Culvert in Stoke St Gregory near the turn to Windmill – part of the Sedgemoor Old Rhyne system; in South Somerset – Ding Bridge in Horton parish, which carries the River Ding under the A358 between the A303 roundabout near Horton Cross and the turn to Broadway; Battspool Culvert and Battspool, south of Wincanton, between Brain’s Corner and Rodgrove Stud, near the turn to Batchpool Lane, where two tributaries of the River Cale meet at a junction; Moor Lane A, on Moor Lane, Wincanton, just north of the A303, on a tributary of the River Cale at the back of the Bennetts Field Trading Estate, and Moor Lane B, just to the south of the A303.
Not yet achieved: South Somerset – Cockhill South – Part of a larger improvement / strengthening scheme planned for 2018-19, at Thornymarsh Lane, south of Cockhill near Castle Cary, on the River Cary; West Somerset – Ford Twin Arches, awaiting Environment Agency consent, at Ford Bridge on the River Avill, beneath the A396 near Timberscombe. Expected start date mid-April 2018.
Carried forward from 2016-17 – Achieved: West Somerset – Monksilver, near The Notley Arms.
Somerset County Council’s Highways Department empties gullies in flood- susceptible areas once a year. The SRA funded an additional six-month round for 17,800 of the highest-risk gullies in these at-risk areas. The purpose was to keep roads open, make them safer, preserve access for communities, and safeguard properties from flooding. 8,883 gullies (49.9% of the initial target figure) were given an extra emptying. Numbers were fewer because of issues to do with the bedding in of a new contract and the need to ensure best value. Partly achieved: Hundreds of Somerset locations benefited from this extra work. Places covered – listed by council ward – were: Alcombe, Bishop’s Hull, Bishop’s Lydeard, Blackdown, Blackmoor Vale, Bradford on Tone, Bridgwater Eastover, Bridgwater Fairfax, Bridgwater Hamp, Bridgwater Victoria, Bridgwater Westover, Bruton, Brympton, Burrow Hill, Butleigh & Baltonsborough, Camelot, Cannington & Wembdon, Cary, Chewton Mendip & Ston Easton, Comeytrowe, Cranmore, Creech, Croscombe & Pilton, Doulting & Nunney, East Polden, Curry Rivel, Glastonbury St Benedict’s, Glastonbury St Edmund’s, Glastonbury St John’s, Glastonbury St Mary’s, Huntspill & Pawlett, King’s Isle, Knoll, Langport & Huish, Martock, Milverton & North Deane, Minehead Central, Minehead South, Monument, North Curry & Stoke St Gregory, Moor, Neroche, North Petherton, Northstone, Norton Fitzwarren, Postlebury, Puriton & Woolavington, Quantocks, Rodney & Westbury, Ruishton & Creech, Shepton East, Shepton West, South Petherton, Staplegrove, St Cuthbert Out North, Taunton Fairwater, Taunton Lyngford, Taunton Manor and Wilton, Taunton Pyrland & Rowbarton, The Pennards & Ditcheat, Tower, Trull, Turn Hill, Wedmore & Mark, Wellington North, Wellington Rockwell Green & West, Wells Central, Wells St Thomas, Wessex, West Monkton, West Polden, Wiveliscombe & West Deane, Wookey & St Cuthbert Out West, Yeovil South.
Under existing budgets, Somerset County Council’s Highways Dept can only afford to jet drains when a bad blockage has occurred. SRA funding allows for earlier preventative maintenance at locations known to suffer problems with flooding. Drain jetting sites feature on annual gully rounds; final selections are made using local knowledge and professional judgement.
Achieved: Locations that benefitted from this work – listed mainly by parish – were: West Somerset – Brompton Ralph, Brompton Regis, Brushford, Carhampton, Crowcombe, Dulverton, Exford, Exmoor (Simonsbath to Challacombe), Holford, Luxborough, Old Cleeve, Luccombe (Horner & West Luccombe), Porlock, Minehead, Sampford Brett, Withycombe. Taunton Deane – Cotford St Luke, Durston, Fitzhead, Kingston St Mary, Langford Budville, Milverton, Ruishton, Staple Fitzapaine, Stoke St Mary, Taunton, Trull, Wellington, West Buckland, Wiveliscombe. Mendip – Chilcompton, Clapton, East Pennard, Frome, Litton, Pilton, Pylle, Shepton Mallet, Upton Noble, Wookey. Sedgemoor – Berrow, Cannington, Greinton, Lympsham, Moorland, North Petherton, Spaxton (including Merridge Hill), Westonzoyland, Woolavington. South Somerset – Ash, Brewham, Bruton, Chilton Cantello, Charlton Mackrell, Ilton, Limington, North Barrow, Queen Camel, Tatworth and Forton, Tintinhull.
Reactive drain jetting was carried out in Mendip at Garston Street in Shepton Mallet.
Countywide targeted edge of road clearing
The aim of this SRA-funded action is to reduce flood risks by stopping detritus entering and blocking drainage systems. Roadsides in rural areas highly susceptible to flooding are therefore swept after trees have shed their leaves. The work is delivered for the SRA by Somerset County Council’s Highways Dept; it is an extra activity for Somerset because the county council does no other sweeping. Local knowledge and professional judgement are used in choosing sites and (where possible) road-edge clearing is integrated with other preventative maintenance activities such as extra gully-emptying. Partly achieved: Work was done in Sedgemoor at Brean (Warren Road, Brean Down), Compton Bishop (Webbington Road, Vernon Lane, Church Lane, Bourton Lane) and Spaxton (Merridge Hill, Bush Road, Bush Lane, Parishlands; Courtway Lane and Lower Merridge). This year’s activities were limited because of issues to do with the bedding in of a new contract and the need to ensure best value.
Accurate information enables Somerset County Council’s flood risk team to identify issues and to encourage the owners of watercourses and structures to take responsibility for them. If need be, CCTV survey results also help the team to carry out enforcement. In 2017-18, surveys have been used to address local flooding problems and local concerns about the condition of culverted watercourses; inform investigations; and support proposed schemes.
Success stories include the identification of a blockage in a culvert in Charlton Musgrove, which was subsequently unblocked by its owner. A neighbour – whose home had been in danger of flooding internally in 2016 – got in touch just before Christmas 2017 to say thank you for the work done. It was reported that the system was now working well even in heavy rain.
The CCTV budget has also been used to support a Parrett IDB investigation for the SRA into problems with surface water flooding in Moorland. The surface water drainage system here is based on an old agricultural network of ditches. As the village has grown, householders and developers have filled-in, culverted and piped many sections of ditch and several key locations have been found to be blocked or obstructed. Problems include the dumping of garden waste, and a lack of maintenance by property owners. SRA-funded CCTV surveys have been helping to establish the true extent and nature of Moorland’s difficulties. It is then hoped to better establish people’s responsibilities for maintenance and to develop a shared understanding with Moorland residents about the way their village drainage system works and what needs to be done to make sure it works well.
Being achieved: Surveys completed in: West Somerset – Cutcombe (Luckwell Bridge, Long Lane – one ton of road plainings removed from system), Old Cleeve (Roadwater Road), Withypool (Withypool Cross to New Bridge); Taunton Deane – Bishops Lydeard (Hearne Lane), Creech Heathfield (Charlton Road), Curry Rivel (Church Street – to support 2018- 19 Somerset County Council scheme to alleviate Primary School flooding), Pitminster, Wiveliscombe; Sedgemoor – Enmore (Enmore Road x2), Moorland (Northmoor Green Road and Church Road), North Newton (Coxhill Farm); South Somerset – Charlton Musgrove, Cudworth, Fivehead (Lower Cottage Lane), Ilchester (The Mead), Ilminster (Shudrick Lane – to support 2018-19 Ilminster flood alleviation study), Misterton (four locations, partly in support of a Somerset County Council flood alleviation scheme after six homes flooded in February 2016), Norton sub Hamdon (five locations); Mendip – Frome (Forest Road).
Unspent funding will be used for more CCTV surveys in 2018-19.
Local flood risk management measures
For the SRA, Somerset County Council and contractors Skanska have been tackling extra cases of property and/or highway flooding from surface water and ordinary watercourses. Funding carried forward from 2015-16.
Achieved: Old Cleeve to Blue Anchor (pictured above): Surface water flooding was causing trouble for road-users and householders. After a CCTV survey in 2016-17, a detailed design was prepared for extra drainage. This was installed in autumn 2017. Being achieved: The design of a scheme to intercept surface water is being finalised for Frog Lane, Enmore, after extensive engagement with residents and landowners and some additional survey work. Construction will be programmed once problematic issues such as access have been finally overcome.