A proposal to increase the budget for sediment removal from three of Pukekura Park’s lakes has been declined by the Monitoring Committee.
The committee instead recommended the re-tendering of the project’s contract for an estimated cost of $1.2 million be considered as part of the Long-Term Plan. The full Council will consider the committee’s recommendation at its meeting on 6 May.
“The committee believes it is better to consider this project alongside all other proposed projects during the LTP, ” said Chairman Craig McFarlane.
Last year the Council stopped a sediment-removal dredge on the Main Lake when its dewatering system did not work as intended, and clogged the Serpentine with fresh sediment. The subcontractor then ceased operating, making the main contractor unable to continue.
The sediment removal is part of a larger water quality improvement project in the park which has resulted in wetlands and forebays being built to trap sediment from three streams that feed the lake system, and strengthened the edges of the main and fountain lakes.
Other work includes building a second outlet from the Main Lake to the Fountain Lake to flush water through a stagnant area of the Fountain Lake near the Hatchery Lawn, and improving the structures that operate the lakes’ water levels.
Research has shown the lakes’ sediment has levels of copper, lead and zinc that are above the guidelines set by the Australian and New Zealand Environment and Conservation Council, and that when dissolved oxygen in the water is low the sediment releases phosphorous that increases weed growth.
The anaerobic sediment also causes odour issues in summer, and its depth makes the top of the Main Lake too shallow for row boats to use.
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Press Release, April 1, 2014