SRA Annual Report 2023-24: River Sowy – King’s Sedgemoor Drain Enhancements Scheme (Phase 1)
The River Sowy is also known as the Parrett Flood Relief Channel. It was created between 1969 and 1972, to take excess water away from the River Parrett near Aller, downstream of Langport. Water flows into the Sowy through a sluice called Monk’s Leaze Clyse near Combe north-west of Langport. It goes down via Beer Wall beneath the A372 near Othery to King’s Sedgemoor Drain (KSD) near Greylake, then it re-joins the Parrett through Dunball Sluice, 22km (13.5 miles) after it went through Monk’s Leaze Clyse.
The SRA has funded improvements to the Sowy-KSD system since 2016. The main aim of Phase 1 Enhancements has been to increase the amount of water that can flow, in a controlled way, through the Sowy-KSD system, and thereby help to reduce flood risks for homes, businesses and roads across 150 square miles of the Somerset Levels and Moors. SRA partners have also needed to ensure that legally-protected wetlands of international importance are not made less wet, as a result of more water being kept in river channels. For example, around 100 water level management control structures have been upgraded. These help to maintain and improve habitats.
Activities in 2023-24
The Environment Agency, as an SRA partner, finished refurbishing Parchey Tilting Weir in May 2023 and Level Rhyne outfall in August 2023. The aim was to enable these structures to cope with more water flowing through the KSD and to keep that water in channel, not let it leak out onto land nearby through (for example) poor-quality headwalls or unsuitable valves.
Parchey Tilting Weir was in poor condition. Works included:
1. the installation of a new tilting weir, new sheet-pile wingwalls with reinforced concrete capping beams, and a new winch mechanism for the flap valve already there.
2. To comply with Eels Regulations (designed to help these endangered creatures survive and increase in numbers), a new eel pass was fitted.
3. To meet current operator and public health and safety standards, the fencing and railings were replaced, and new open mesh flooring was installed with safe access and egress, to lessen the risks of falling from height and working in confined spaces.
The Environment Agency also completed Level Rhyne outfall works in August 2023. These involved replacing a through-embankment culvert pipe, which was old and in poor condition, with a new pipe; installing new watertight headwalls at both ends of the pipe (the old inlet and outlet were leaky); and fitting an eel-friendly, soft-closing flap valve at the outlet to stop KSD water getting into the pipe. The ground above the pipe was upgraded to help support the weight of farm machinery and construction vehicles needing to move along there. Text continues below images of Level Rhyne construction works and completed headwall.
The Environment Agency’s project team also completed designs for a range of similar improvements at Chedzoy Tilting Weir and KSD Back Ditch outfall, and they bought various necessary components. Works were meant to be done in the autumn but a problem with national Environment Agency framework contracting rules meant that a new contractor had to be found. Works were re-scheduled to January 2024, but could not be done then because the two sites were under water. Faced then with various financial impediments to rescheduling works again to the spring or summer, the Environment Agency decided that it could not continue with these schemes, instead it would hand over its designs and purchases to another SRA partner.
The Parrett Internal Drainage Board (IDB) agreed that it would investigate ways forward for the SRA. The Parrett IDB had previously agreed (in November 2023) that it would also work on plans for the completion of up to 1.8kms of KSD left bank-raising. A range of activities followed, such as reviews of existing plans and designs, site inspections and detailed engagements with consultants and contractors. The SRA Board’s declared intent remains that Sowy-KSD Phase 1 works should be finished.