High Street Water Main Upgrade

Overview Waimakariri District Council is seeking a contractor to deliver the High Street Water Main Upgrade, comprising water main renewal, roading infrastructure upgrades, and stormwater works along the High Street corridor. The scope outlined below reflects the proposed project scope and may be subject to change and refinement resulting from the Early Contractor Involvement (ECI) process and ongoing design works. Scope Water Main Upgrade the existing DN200 water main between King Street and the Railway Drain to a new DN300 water main Renew all adjoining connecting pipes connected to the existing DN200 water main within the High Street corridor, generally on a like-for-like diameter where the mean renewal dates fall within the next 10 years, including: Replacement of approximately 14m of DN100 PVC (1989 install) (Asset: 170780) extending south of the High/King Street roundabout Replacement of DN100 AC (1981 install) (Asset: 170781) servicing 215 High Street, up to the boundary with an isolation valve at the boundary Replacement of approximately 13m of DN150 PVC (1989 install) (Asset: 171531) crossing towards Percival Street from the existing main Replacement of DN100 PVC (1962 install), approximately 15m, crossing from Victoria Street (Asset: 170812), noting a likely GIS records issue Replacement of the DN100 (1988 install), approximately 14m (Asset: 171451), crossing towards Cone Lane Investigation of the existing abandoned main between Ashley Street and the railway crossing to assess its suitability as a carrier for a rider main, and subject to condition assessment, installation of a new rider main within the abandoned main or construction of a new rider main to connect to the existing lateral connections Abandonment of the existing 100 uPVC connection at the Ivory/High Street intersection (Asset ID 173437) and reconnection to 150 PVC where suitable Installation of new tees with isolation valves at intersecting mains to the proposed DN300 pipe to allow future renewals, minimising connections by using a 4-way connection instead of two separate connections where possible Installation of a DN63 rider main along the northern footpath within the existing abandoned main, transfer of applicable service laterals to the new rider main, and renewal of laterals through to the property meter and backflow prevention assembly Installation of new metered connections with appropriate backflow prevention for landscaped concrete build-outs, tree pits and garden areas requiring irrigation Roading Infrastructure Upgrade (Sumps) Upgrade eight existing stormwater sumps to double side-entry sumps Identify services passing through two manholes and liaise with the relevant utility providers to arrange relocation Upgrade the existing DN225 stormwater pipe (Pipe ID 300543) to DN300 where confirmed by design, rationalising bends and improving connections to improve hydraulic conveyance where practicable Locate Sump ID 277596 and Manhole ID 274670, install an appropriate sump grate, and assess whether the existing structure requires replacement or modification Reconfiguration of the parking lines on the northern side of High Street between #102 and #124 to provide longer parking bays for existing mobility car parks Stormwater Installation of approximately 150m of new DN600 stormwater pipe connecting from existing Manhole ID 281884 at the Ashley Street/High Street intersection to existing Manhole ID 283734 adjacent to the railway drain Connection of the existing DN225 uPVC stormwater pipe (Pipe ID 294766) into the proposed DN600 stormwater main Hydraulic assessment of the existing DN600 stormwater main (Pipe ID 299808) and associated manhole upgrade where required, particularly to confirm capacity following additional inflows from the proposed DN600 main Roading Reinstatement of all trenchlines and other disturbed road corridor surfaces to match the existing adjacent surfaces in accordance with the National Code of Practice for Utility Operators Access to Transport Corridors Staging A preliminary staging plan ("High Street Water Main Renewal - Disruption Planning - Open trenching - V2-Plan no") is attached to provide an indication of how the scoped works could be delivered. Further refinement will take place through design and the ECI process. Out of Scope No wastewater renewal works are required within the High Street corridor. Consideration was given to installing a new wastewater main between Durham Street and Percival Street to enable the removal of existing mains from private property, however these mains are largely in areas that do not unduly affect the ability for further development and can be relocated to alternative locations relatively simply as required No additional road or footpath upgrades are identified No greenspace upgrades or renewal requirements were identified, other than provision for new irrigation lines to the concrete build-outs No other utilities upgrade works are identified