Section 38 Whixall Manor Drain Diversion Completion

Description

Summary of the S38 project Fenn's NNR Section 38, Reeves' Fields, is in the West Midlands near Whitchurch and Wrexham. It is situated towards the southeastern perimeter of the internationally important Fenn's, Whixall, Bettisfield, Wem and Cadney Mosses Site of Special Scientific Interest (S.S.S.I.), in the Fenn's, Whixall & Bettisfield Mosses National Nature Reserve (N.N.R.). The Marches Mosses BogLIFE Project (LIFE15NAT/UK/000786) terminated in March 2023, and now unfinished works are being tackled. The Project aimed to allow better control of water levels to enable wetland habitat to be restored on land which has been converted from peatland to peaty fields. Reeves's fields used to be peatland, and originally formed part of the south-eastern edge of Whixall Moss. In 2009 the Whixall Manor Drain, which was taking polluted and mineral-rich water up from local Cottages onto and across the centre of the NNR, was diverted nearer to the edge of the Moss but ended at a new culvert under the track leading north from Roundthorn Bridge, Whixall. The downstream 195m of the Diversion was left in the existing channel, with the intention to complete the diversion by excavating a new channel farther south during the BogLIFE Project. However, the Project was completed before this last part of the Diversion had been executed. Overall, this Scheme will rewet at least 4.25ha of deeper peats in Section 38 plus support water levels in adjacent Whixall Moss to the north. This Scheme involves: 1. Excavation of a new 210 m-long open channel nearer to the edge of the peat body. The open channel lengths will have a 1.0m bed width with 1:1 side-slopes. 2. Damming of upper length of existing course of Whixall Manor Drain. Damming of the drain will take place at 3 sites (D1, 6m long, D2 3m long, and D3 at 6m long). The first dam (D1) will be positioned immediately downstream of the upper end of the Diversion and the final dam will be upstream of the entry point into the Whixall Moss Main Drain. D1 dam will utilise surplus peat from the first 12m-long excavation of the Diversion. Dams D2 and D3 will use peat from shallow borrow pits. Each will incorporate a 300mm U-pipe to control water levels to allow for any future emergencies such as blockages in the new channel. To make D1 watertight it will also need L8 trench sheets. NE will supply all materials, which will need to be collected from the nearby Manor House NNR Base. The contractor will need a tracked excavator and one or two tracked dumpers. It is anticipated that this contract will be awarded for a period of 2 to 3 weeks to end no later than 02/10/24, unless there is substantial disruption from adverse weather. Additional information: To apply for this opportunity you must submit your quotation meeting the requirements detailed in the Request for Quotation (RFQ) attached. Your response must be sent to joan.daniels@naturalengland.org.uk, copied to peter.bowyer@naturalengland.org.uk by 09:00 on 27/8/24. If you have any clarification questions linked to this opportunity or the procurement process please submit these via email to joan.daniels@naturalengland.org.uk or Nathan.brake@naturalengland.org.uk by 21 August 2024 at 11:30am . Please note that, unless commercially sensitive, both the question and the response will be circulated to all tenderers.