Work begins on final sector of main trunk sewer renewal project

Timaru District’s $36 million main trunk sewer renewal programme is continuing on schedule this month.

The letting of a $5 million contract in November for Stage 5, which involves the laying of large-diameter pipes from behind McCain food processors in Washdyke to the Timaru District Council’s Aorangi Road milliscreen plant, signals the closing phases of the project. So far, large-diameter sewer pipes have been laid from Station Street across Caroline Bay to Virtue Avenue (Stage 1); from a point just north of Alliance Smithfield around the Washdyke Lagoon to McCains (Stage 2); three 400 metre - long tunnels around the foreshore (Stage 3), and the joining of those tunnels to the new pipelines (Stage 4).

This leaves the two-and–a-half kilometre long Stage 5 as the final sector in a project designed to meet improved waste water standards required for the recently-granted ocean outfall discharge-for-treated-wastewater consent by Environment Canterbury. The consent allows Timaru District to discharge treated wastewater to the sea for the next 35 years and has offered long-term financial sustainability to industry and residents.

Council district services manager Ashley Harper said Hawkins Infrastructure had been awarded the contract for Stage 5 because of its expertise and very competitive price. The job would take 24 weeks from January. This company carries out work nationwide.

“This is a key element in Timaru’s improved wastewater standards because this month tenders will be called for the construction of the Aorangi Road oxidation ponds and pump stations, which will treat domestic wastewater prior to its discharge to the sea,” Mr Harper said. Tenders would be awarded in February.

The discharge consent allowed the council to choose an oxidation pond treatment of domestic wastewater. Industrial wastewater does not need a centralised treatment plant, although tougher discharge conditions are to be imposed on industry.

Mr Harper said that because the piping of wastewater occurred separately in two waste streams, domestic and industrial, twin pipes were required to carry the effluent to the council’s 60-hectare Aorangi Road treatment site. The pipes, ranging in diameter from 150mm through to the main line of 1400 mm, were of high-density polyethelene (HDP), and although the industrial volumes were less than domestic, industrial effluent was 10-times more concentrated.

The council owns or has easements over all property involved in the new pipeline and infrastructure work.

ENDS

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