NRV Culverts NM Corner

Descriptions

Description of Works Refer to attachment: Natural England Specifications of Requirements - NRV Culverts NM Corner Replace three existing 450mm culverts fitted and non-return valves (flap valves) previously installed in the 1990s. Non-return valves were fitted to act as a water supply into the North Moor Corner Raised Water Level area when water levels within internal ditches are lower than external levels. Structures to allow passage of water into the raised water level area, but in an emergency can also be opened to allow evacuation of water during flood events. The wooden headwalls of the culverts are severely degraded and in places material compacted around the culvert pipes has collapsed into the field and ditch. Replacement structures are required. Each replacement culvert must be/have: •Rigid twin-walled plastic pipe •Internal pipe diameter 450mm •Pipe length 6000mm •Culvert pipe surround of geotextile membrane and clean, crushed, locally sourced stone •Motorway barrier headwalls with 450mm non-return (flap) valve (vertical component of headwall required to reach approximate depth of 3500mm to anchor the structure to the clay bed beneath the peat soils) •12-foot metal gate with galvanised metal gate posts and wooden wings Working Method will follow: Somerset IDB Gateway Construction Culvert Sequence Guide - utilising Steel Motorway Barrier Headwalls Working area must be isolated with sheet piling and drained prior to commencement of works. Location of works: Wisteria Farm, Middlemoor Drove, North Newton. TA7 0BT. What3Words for the three culvert locations: crowds.supreme.swerving prowling.manicured.safari nuggets.rejoined.grant