Timaru District Council

Contract 2745 - Waihi Outfalls storm water improvements

TDC is seeking a contractor to undertake stormwater improvements at existing stormwater outfall WAIS-SO16171 (herein referred to as Stormwater Outfall 10 (SWO10)). SWO10 discharges to a slope which is located on the banks of the Waihi River. However, an existing pathway (the Geraldine Sculpture Trail) runs parallel to the Waihi River between the discharge point and the Waihi River main channel. The pathway has periodically washed out in previous rainfall events, creating a health and safety issue for pedestrians on the Geraldine Sculpture Trail and increasing the likelihood of rock displacement on an existing Environment Canterbury groyne.
The purpose of this contract is to mitigate against erosive forces encountered due to discharge from SWO10 and provide protection for the general public utilising the Geraldine Sculpture Trail and the existing Groyne.
The scope of the contract is to undertake the following tasks to limit erosion due to significant flows from both SWO10 and the Waihi River.
• All erosion and sediment control,
• Earthworks and construction,
• Installation of a new rock lined swale and a boardwalk with balustrade above
• Reinstatement and rectification of any areas impacted during construction
• Installation of 1.0-1.2 m Ø boulders to tie erosion protection into an existing groyne in Waihi River
We are looking to engage an experienced contractor with demonstrated capability to deliver the scope of the contract, apply appropriate methodology and meet all quality assurance requirements. In particular, we wish to engage a contractor that has best practice at heart, by installing appropriate erosion and sediment controls and actively taking steps to limit the discharge of sediment to the receiving environment. Environment Canterbury (herein referred to as CRC) will have a stake in this contract due to their adjacent river groyne asset, that may be impacted by these works. Therefore, methodology will be subject to CRC approval.