In April, the team began work on the Timaru District Council’s $A14 million main trunk sewer upgrade. The project consists of three drives, all approximately 400 m in length. They are spread from the Washdyke Lagoon to Caroline Bay. The Harker team is scheduled to complete the job by the end of July 2009.
The team started from the lagoon end and headed south, using drill and blast for the first 150 m. The team then split and half headed north with an EX50 to eventually meet in the middle. Harker has also completed 106 m of open cut at the start of the most southern drive. This will be laid in 2.5 m OD concrete pipe and used for access into the ringbeam and lagging tunnel.
Project Manager Mr Bishop says that they are working 24 hours a day on the tunnel boring machine and day shifts on the conventional section. “The tunnel face is a split of clay and fractured basalt. Although the rock proved difficult to blast due to the clay seams, we have been averaging about 1.5 m per shift.
“The open cut had to be extended as we encountered some unexpected boulders in fill material; otherwise it’s been as the geotechnical reports predicted. We are enjoying the challenges of the job, which is both drill and blast with sections of ringbeam and lagging.” Harker now has 20 men onsite.
The company also has a $NZ10 million project underway for Auckland City – a storm water system upgrade – as well as a $NZ7 million sewer pipeline upgrade for North Shore City.