Tender: Replacement of Four Culverts and Restoration of 700m Ditches at Canada Farm Meadows, Shapwick Heath SSSI

About

Contractor needed to replace four defunct culverts and restore 700 metres of ditches across 10.6 hectares of floodplain grazing marsh at Canada Farm Meadows, part of Shapwick Heath SSSI. The site is species-rich floodplain meadow on deep peat (average 2.00 m) where existing ditches are heavily silted, partially scrub-covered and dry for much of the year; restoring the ditch network and replacing culverts will allow year-round water delivery, benefit wet grassland species and breeding waders, and help raise groundwater to reduce peat oxidisation and CO₂ emissions. The requirement is to install 4 culverts suitable for cattle and agricultural machinery and to restore 700 m of ditch, following the Somerset IDB Gateway Construction Culvert Sequence Guide using Galvanised Steel Motorway Barrier Headwalls and complying with Somerset Internal Drainage Board consent details: existing channel depth 900 mm; rigid twin-walled plastic pipe 600 mm diameter and 6000 mm length; backfill of clean crushed locally sourced quarried natural stone compacted with a road-roller; 400 mm cover over the pipe; and ditch width 2700 mm. Works must provide a dry working area, deliver solid, stable and stock-proof structures on completion, and include woody vegetation removal, silt removal and disposal, and disposal of vegetation matter. General considerations include working on peat soils, within a wetland and SSSI, potential protected species issues, additional environmental considerations and presence of livestock. The main outputs are installation of 4 culverts and restoration of a 700-metre ditch system.