Aniwhenua Head Pond Remediation

Nova Energy

Scope of Works

This Contract involved significant repair work to rectify seepage from for the head pond dam at Aniwhenua into the Rangitaiki River.  Works involved draining the water from the head pond and canal to construct significant and complex flood protection works.

This was a highly sensitive project with significant time restraints to take advantage of fine weather early in the year.  There was a huge, push 7 day weeks and 24 hours (2 shift days worked), to ensure this project was completed before the Winter rain arrived.

This project specifically involved the following works:

  • Removal of existing rip rap on headpond embankment face and base.
  • Construction of temporary EPDM lined coffer dams.
  • Temporary diversion of stream to enable repair works to be carried out.  This involved the installation of a 1800mm dia above ground fibreglass pipe and forebay wall.
  • Excavating the extent of damaged embankment material, placement and compaction of new low permeability ash fill and filter material.
  • Supply and installation of HDPE liner and testing.
  • Construction of liner underdrain system and collector pipe and prepare liner subgrade with imported aggregate.

Despite the complexity of this operation and having to deal with many technical challenges and rain events, Waiotahi Contractors Ltd were able to complete this Contract within budget and on time.

This Project was the winner of Category 1B of the 2017 CCNZ Construction Excellence Awards.

Quick Facts

  • Contract Value: $2,780,000.00
  • Location: Aniwhenua Dam
  • Duration: February 2016 to May 2016
  • Completed on time and within budget

Project completed within a very tight timescale prior to Winter.