Observers From The Environment Agency And Parrett Internal Drainage Board, On Board Van Oord's Water Injection Dredging Vessel Borr, See Water Being Jetted Out From Borr's Water Injection Bars, Raised For Demonstration Purposes Above The Surface Of The River Parrett Near Moorland.

New dredging to cut flood risks on Somerset Levels

A new section of the River Parrett is to be dredged for Somerset Rivers Authority, to reduce flood risks to local people, properties, roads and land.

Large quantities of silt will be removed from 1.37miles (2.2km) of the river between the village of Moorland and the M5, to increase its capacity to carry flood water.

Dredging is due to start around Sunday 17 January/Monday 18 January (slightly delayed from Thursday 14 January because of a haulage problem). The job is being delivered for Somerset Rivers Authority (SRA) by the Parrett Internal Drainage Board (IDB), working closely with the Environment Agency and Natural England, and using Growth Deal funding from the Heart of the South West Local Enterprise Partnership.

Contractors Van Oord’s water injection dredging vessel Borr will shift around 22,000m3 of fine sediments from the bed of the Parrett, down beyond Northmoor Pumping Station. Targeted jets of water will separate and mobilise particles so they can be washed away on the outgoing tide.

(Pictured top: Borr in display mode, with water injection bars raised, during a short trial near Moorland in January 2020. The bars are usually submerged.)

Three main reasons for this dredge

Cllr David Hall, Chair of Somerset Rivers Authority, said: “Work along this stretch of the River Parrett is important for three main reasons.

“Firstly, it will reduce flood risks for properties in the Northmoor area.

“Secondly, it will help to reduce agricultural damages, particularly from spring and summer floods of the kind that we saw locally back in 2012.

“Thirdly, because of the better possibilities it creates for managing flows of water around the Somerset Levels, it will help us to make further improvements, like those planned for the River Sowy and King’s Sedgemoor Drain later this year. All these things together will benefit a large part of the Somerset Levels.”

Cllr Hall added: “The Parrett IDB and Van Oord are operating within challenging coronavirus restrictions and I would like to thank them both for pressing on with this essential public service at a very difficult time for us all.”

How River Parrett dredging has recently developed

The new dredge down towards the M5 has several years of SRA partnership work behind it. Following the devastating floods that hit Somerset in 2013-14, the Environment Agency dredged 5 miles (8km) of the Parrett and Tone in 2014, down to Northmoor Pumping Station. The SRA funded a further 0.47 miles (750m) of dredging downstream of Northmoor Pumping Station in 2016, then another 1.4 miles (2.2km) of Parrett dredging between Stathe and Burrowbridge in 2019.

The SRA has also been funding regular maintenance dredging, since 2016 using water injection dredging techniques. Compared with conventional techniques involving big excavators, water injection dredging is less disruptive to residents and has less impact on the environment. It is also quicker and cheaper.

At their most recent meeting in December, SRA Board members heard that £441,000 was being saved on the Northmoor to M5 dredge by using water injection dredging techniques. This money will now be used to fund other flood risk reduction activities across Somerset, in the SRA’s Enhanced Programme of works for 2021-22, which the SRA Board will decide upon at their next meeting in March.

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