Drainage Asset Mapping

Tender description

A Drainage Asset Survey is required to improve knowledge of the location and condition of highway drainage in Wigan Borough. The objectives of the commission are to provide Wigan Council with a flexible service to undertake investigations in advance of capital maintenance schemes, to carry out drainage investigations and cleansing services for Lead Local Flood Authority (LLFA) schemes, to complete asset mapping and drainage proofing across the network as directed, and to expand, maintain and update the Council's asset inventory system. The Service is to include the location and CCTV survey of the currently unmapped pipework that links the gullies in the survey area to the wider drainage network. Wigan Council holds good data on gully locations(this information will be provided to the successful contractor in digital format for uploading to a software mapping system) on condition, United Utilities holds data on public sewers, but there is limited information on the pipework and connections that the gully network utilises between. Additionally, there is limited information on existing culverts and chambers outside the above network. The Service will specifically require locating and mapping gully connections and any other pipes in order to show how the gullies in the survey area connect to known drainage infrastructure; the provision of CCTV survey reports and footage of these gully connection pipes according to the WRc Manual of Sewer Classification; hydraulically cleaning all pipework and gullies prior to the survey; and undertaking any traffic management in support of these tasks. The contract will also require the accurate recording of all work and any variations or additions to the inventory supplied using a software mapping system (either Wigan Council's preferred system or a similar system to be proposed by the tenderer and approved by Wigan Council), the maintenance and development of the system during the period of the contract, and the provision of access to the data for a period of 36 months following the completion of the twelvemonth contract period. This Invitation to Tender is divided into 4 Task Orders: Task Order 1 — ‘A’ classified roads (approx. 132 km in the Borough with 6 462 mapped road gullies), Task Order 2 — ‘B’ classified roads (approx. 114 km of ‘B’ and‘C’ class roads in the Borough with 2 943 mapped road gullies on the ‘B’ class network), Task Order 3 — ‘C’classified roads (approx. 114 km of ‘B’ and ‘C’ class roads in the Borough with 2 412 mapped road gullies on the ‘C’ class network) and Task Order 4 — ‘Hotspots’ (there are 34 flooding hotspots in the Borough outside the ‘A’, ‘B’ and ‘C’ class network with 152 mapped road gullies). Services will be issued through individual Task Orders at Wigan Council's choosing and Wigan Council reserves the right to amend the limits of the asset mapping to ensure that the provision of the Services does not exceed available expenditure. It is intended that Task Order 1 will be issued initially with completion by 13 October 2017 with the remaining Task Orders being issued by Wigan Council at its choosing within the 52 week contract period based on contractor performance and available expenditure in line with the Service Information. Tenderers should note that Wigan Council has a proactive robust maintenance system to monitoring levels of silt build up in gullies across the Borough with an annual clean of the gullies and associated interconnecting pipework on the strategic network and flooding hotspots. Further details regarding gully cleaning, anticipated volumes of silt for disposal and the length of interconnecting pipework is available in the Invitation to Tender documentation. Tenderers are directed to the Invitation to Tender documentation which contains a full Specification for this service. Keywords: asset, mapping, gully, engineering, environment, Drainage