First sod turned in $15 million domestic sewage treatment upgrade

One of Timaru District's biggest sewerage improvement projects got under way this week (eds: Monday, April 16) with the turning of the first sod on the $15 million domestic wastewater treatment plant upgrade on Aorangi Road at Seadown.

Timaru Mayor Janie Annear used a shovel to ceremoniously launch the project, a major advance in the way the district processes, treats and discharges its wastewater. Her actions were the culmination of years of council planning as part of the Timaru District Wastewater Management Strategy.

The 18-month construction timeline will see major earthworks over a total of approximately 48 hectares on both sides of Aorangi Road as well as a number of separate projects that will achieve the on-site separation and treatment of industrial and domestic wastewater flows.

More than 30 hectares of primary oxidation ponds, eight hectares of maturation ponds and 10 hectares of wetlands will be constructed.

Turning the first sod, Mrs Annear told a gathering of council staff and elected representatives, Environment Canterbury officials, the scheme’s design consultants from CH2M Beca and representatives from contractors Downer NZ Ltd and subcontractors Rooney Earthmoving Ltd, that the district was pleased and proud to be able to provide such an environmentally sustainable advance in its infrastructure.

“This project will mean a significant change to the way the district’s sewage is treated and will provide not just for our present generation but for generations to come,” Mrs Annear said.

She said the new work follows a five-stage upgrade of the main trunk sewer over the last few years designed to provide the separate waste streams needed to upgrade the treatment of domestic sewage to meet the district’s wastewater discharge requirements now and well into the future.

Announcing the awarding of the main contract to Downer, with Rooney Earthmoving a significant sub-contractor, council drainage and water manager Grant Hall said industrial sewage flows would continue to be treated in the existing milliscreen plant at the Aorangi Road site, but domestic flows would be re-routed from the existing plant to the new wastewater plant to be built alongside.

“The domestic flows will be treated in the wetlands, then recombined with the industrial flows and discharged through the existing ocean outfall,” Mr Hall said.

Although the earthworks to build the oxidation, maturation and wetlands areas were extensive, they were reduced by the construction method to be employed, he said.

“The ponds are to have an impermeable liner of silt first harvested from the site of the excavation and then returned to the ponds once their shape has been formed,” Mr Hall said.

“By using the silt harvested on site the need to truck in liner material from elsewhere is eliminated. This will seriously reduce the impact of the work on the community and mean substantially less road and site traffic.”

There will also be changes in the way sewage from the towns of Pleasant Point, Geraldine and Temuka will be handled with their flows piped into the new maturation pond for further treatment rather than the current situation where it is piped directly out to the ocean outfall.

Funding for the upgrade has been included in the current Long Term Plan and the draft proposed Long Term Plan.

ENDS

© Scoop Media