Dredging: new era advances Natural flood works total 200 New techniques for dredging the Parrett are The Somerset Rivers Authority Board has being tested this November and December, as agreed, in principle, to keep supporting natural Somerset Rivers Authority seeks cheaper and flood management and whole catchment works. better ways of maintaining tidal rivers. The cause is being boosted by the enthusiasm Three weeks of trials are being carried out of farmers such as John Elliott, who was so between Westonzoyland Pumping Station pleased with his leaky pond at Brompton Ralph and Burrowbridge to see how effective water (above), he’s enlisting his neighbours to help injection dredging and agitation dredging can be create a further cascade of ponds. at getting silt moving down to Bridgwater Bay and preserving the River Parrett’s capacity. Just over 200 natural flood management and farm resilience schemes are now either Cllr John Osman, SRA chairman, said: “This is completed, in progress or proposed. The SRA the first time that such trials have been done is putting £550,000 of Growth Deal money from on the Parrett in conjunction with a long-term Heart of the SW Local Enterprise Partnership programme of detailed monitoring. towards the multi-partner Hills to Levels project. “Potentially, new methods offer Somerset big More than 850 farm visits have been made, and benefits: done at the right times, in the right the Farming & Wildlife Advisory Group SW have places, they could be much cheaper, more investigated 40 roads where land management effective, and better for the environment, local works might help solve local flooding issues. residents and farmers.” SRA council tax money has funded the The trials are being delivered for the SRA by the investigation of 50 sites in West Somerset, Parrett Internal Drainage Board with contractors including the areas around Carhampton, Van Oord. Read more: page 2. Roadwater and Monksilver. Somerset Rivers Authority (SRA) exists to For more information about the SRA - or if you’d provide higher standards of flood protection like to receive future copies of The Stream - call than ordinary national funding allows for. The 01823 355111, email [email protected] Stream details past, present and future work. or visit www.somersetriversauthority.org.uk New dredging techniques aim to keep silt moving out to sea The techniques being trialled for Somerset more separated, in a turbulent fluid lower layer Rivers Authority are water injection dredging of their own, slightly different to the surrounding and agitation dredging: two ways of getting and water. Van Oord call this a “density current”: it keeping silt moving. Work must be done when is, effectively, a different material to the water an outgoing tide can carry silt away. around it, so it behaves partly independently. In this state, on an outgoing tide, it should travel: The vessel being used on the Parrett is called the hope is that it will carry down right back out Borr (Old Norse for ‘son’; pictured above). After into Bridgwater Bay, and disperse naturally. being delivered to Dunball Wharf in halves, then re-assembled, Borr motors upstream through Agitation dredging (top right, in Scotland) uses Bridgwater on Saturday night, 12 November. a Farrell attachment, an articulated arm with a cutting device, which rotates, and a suction Three weeks of trials start on Monday, 14 hose. As the cutting head moves towards its November, in conjunction with detailed target area, mud and water are vacuumed up, monitoring before, during and after. Along the and blown back out into the top of the river. The trials section, there is 150% more silt than there idea here is that silt is given much more time to was in April. In places, four times as much. carry before it drops down again and settles. Work therefore carries on from where 2.2km The trials aim to get a better understanding of maintenance dredging was finished earlier of where silt goes and the best ways to keep this year by the Parrett IDB for the SRA. (That it moving. Many different variables will be dredging, and these trials, both maintain the measured, particularly turbidity (how cloudy 8km pioneer-dredged in 2014). water is - and when and where it settles again). How does water injection dredging work? In Five potential benefits of the new techniques: the top left picture (not taken on the Parrett!), the injection bar, spraying water, is raised so • Cheaper – potentially much cheaper. you can see it. Nozzles pump out a high volume • More efficient - letting water carry silt of water. The plan on the Parrett is to lower away should be mechanically more efficient the bar just above the river bed. Surveying has than digging it out and hauling it away with created a very precise profile of the river - and excavators, barges, tractors and trailers. If this profile can be updated in near real-time. As natural processes take silt out to sea, this the vessel passes, it re-measures. A screen on will reduce costs. board shows the relative positions of bed and • Better for the environment – bankside injection point, so it’s possible to see what effect flora and fauna do not have their habitat work is having, and to raise and lower the bar, disturbed other than at the mud level. and vary the pressure and volume. • Better for residents – less traffic coming and going, no road closures. River water is pumped through the injection • Better for farmers – not spreading silt over bar. It’s aimed at the soft silts in the bed of the fields means land does not have to be taken Parrett, so they become super-saturated and out of commission until vegetation re-grows. Doug Challoner, acting chairman of Dunster SRA grant helps flood group. Parish Council and Flood Group member, said: Do you need equipment too? “What it does is, it gives us the confidence that we’re ready, we can deal with problems in the Somerset Rivers Authority has funded a new future. community equipment store in Dunster, with kit to help fight flooding. “It’s brilliant. If any issues occur, we’ll spring into action in ways that we’ve planned for and I am Gear which can now be used by Dunster’s new sure that people will be extremely pleased.” Flood Group includes portable sandbag fillers, sandbags, hi-viz jackets and shovels. The store Grants of SRA money are available to other is sited in the middle of Dunster. communities throughout Somerset via CRISP. Where there is a need, grants can be used to The Community Resilience in Somerset buy things such as generators, headlamps, Partnership (CRISP) gave just over £3,000 from lighting, protective clothing, clean-up Somerset Rivers Authority (SRA) to Dunster equipment, depth markers and dry sheds for Parish Council to support the Flood Group, storage, or to fund training for local volunteers. which has five founding members. For more information about CRISP, email Cllr John Osman, Chair of the SRA, said: [email protected] or check “Surface water is a problem in parts of Dunster out www.communityresiliencesomerset.org.uk during times of very heavy and prolonged rainfall, and when flooding has occurred it’s had In the photo: Nicola Dawson of CRISP (centre) a devastating impact on people, so I’m very with Dunster Parish Council emergency pleased that the SRA and CRISP are backing group members (from left) Geoff Witherford, Dunster Parish Council and the new Flood Alan Vicary, Alan Rigler and Doug Challoner, Group. The store and equipment that we’ve with their new store and some of their new paid for will help Dunster’s volunteers protect equipment. The Flood Group’s fifth founding villagers, visitors, homes and businesses.” member Alan Blackham could not be present. Badger risk reduced by SRA Flood defences put at risk of collapse by badgers have been protected in a scheme funded by Somerset Rivers Authority and delivered by the Environment Agency. Steel sheet piles have been installed in a raised flood bank near Isle Brewers (pictured below) to stop badgers digging right through it. If this had Bony updates on big projects been allowed to happen, flood water could have surged through and destroyed the bank. Cannington: Work to protect 200 homes and the A39 from flooding is progressing well. An No badgers were moved or harmed in the work, SRA contribution of £300,000 enabled this which was carried out by a specialist contractor £4million scheme, led by the Environment under licence from Natural England. Badgers Agency, to go ahead. A flood alleviation channel are a protected species. has been dug beneath the A39. Cllr John Osman, SRA chairman, said: “This Three Roman skeletons (one pictured above) work will help to stop water flooding overland were uncovered during an archaeological into Isle Brewers from the River Isle. The bank investigation. Evidence strongly suggests that is one of several structures that limit and control the area was flooded in the Roman period. flows around the village, and if it had collapsed, restoring it would have cost a lot of money. So Pioneer dredging: New dredging of 750m of I’m pleased that SRA funding has helped to the River Parrett downstream of Northmoor prevent destruction and protect local people Pumping Station was completed in August, and properties.” ahead of schedule and under budget. Raised banks are attractive to badgers on the The work was commissioned and funded by Somerset Levels and Moors because they are the SRA, partly using Growth Deal money from warmer, drier and easier to dig through than Heart of the SW Local Enterprise Partnership cold sub-soil.