GB-Shrewsbury: Deans Culvert

Tender description

Deans Culvert is a single span brick pipe culvert with concrete faced headwall and training wall to the upstream end, there are no wingwalls / headwall to the downstream end. There are no parapets to this structure, however there is a well-established hedge adjacent to the carriageway (note:- this hedge has been cleared for access and replaced with a temporary timber fence as shown on Drawing 62240651-T-103). The structure is situated under the B4373 which is south of Broseley at National Grid Reference SJ 680 003. The culvert was monitored as part of a BD79 inspection regime, on a monthly basis until May 2012, and then annually until March 2017, to assess movement to the existing cracks and the shape of the culvert. There was found to be no significant changes in the readings and repairs were undertaken in early 2014, comprising of pointing radial cracks and infilling any voids. Some of the pointing has exhibited hairline cracking and there is a transverse crack to the soffit of the crown running from the downstream end into the culvert by around 8m. The culvert also exhibits a "sag" in the invert of around 250mm. Shropshire Council have now requested a liner be installed, but without reduction to the culverts capacity. The proposed works include: -  Implementation, maintenance and removal of traffic management system;  Construction of temporary access to the upstream end of the culvert;  Excavation of the carriageway to accommodate a 300mm diameter overpumping pipe;  Reinstatement of carriageway once the pipe is installed;  Site Clearance;  Damming and temporary diversion of the watercourse (pumping) to create a dry working environment through the culvert;  Installation of concrete to the underside and front of the downstream invert;  Placing of 350mm - 500mm diameter stone to the invert at the downstream end of the structure;  Installation of Cured in Place Pipe (CIPP) liner.  Grout to void areas behind the new CIPP liner.  Erection of a timber fence to the upstream and downstream verge directly above the culvert;  Provision of new hedgerow  Erection of a new timber gate to the upstream access.  Removal of the temporary access and making good site. Planned start date 15 June 2020 and planned finish date 10 July 2020