The Principal (Gore District Council (GDC)) requires the replacement of approximately 289 m of DN1000mm “egg shaped” cast in-situ concrete combined foul sewer (sanitary sewer and stormwater) trunk main with a DN900mm RCRRJ (microsilica) pipe. The existing “egg shaped” trunk main has exceeded its end of life, increasing the risk of pipe collapse. Downstream (Wigan Street) of this contract hasrecently been replaced with DN900mm RCRRJ (microsilica) class 2 pipe. The new main shall extend the previous stage of works from Wigan Street, into Hyde Street before realignment from the existing. The new main is to be constructed somewhat offline from the existing to avoid over pumping and reduce risk on the network and Contractor during construction, additionally avoiding existing buildings which have been constructed over top of the existing main. Majority of the new pipe alignment is on the existing pipe alignment and therefore the existing pipe shall be removed as part of this works. The new main alignment has been developed to allow a simple and straightforward open trenching methodology route. The main crosses road corridors, including state highway 1, KiwiRail’s corridor, private property and GDC land (Eccles St playground). To enable programming of the works through KiwiRail property to align with a track siding upgrade for Mainfreight (via KiwiRail), the Principal has opted to separate the contract works into two portions: Separable Portion 1 – Roading Corridor Works and Separable Portion 2 – KiwiRail Corridor Works.

The works within the KiwiRail corridor shall be planned and undertaken in alignment with the KiwiRail team. The design has been completed based on an open trench methodology whichshall be performed while leaving the existing tracks in place to avoid unnecessary track works. It is the Contractors responsibility to confirm the methodology with KiwiRail including permits to enter etc. The KiwiRail land is considered a HAIL site. Excavated materials from within this area shall remain stockpiled on site in an agreed location with KiwiRail.