The existing Clarkson wastewater conveyance infrastructure, does not have sufficient capacity for the future demand in the area. The new sewer, will allow conveyance of wastewater flows from wastewater pump stations located in Ellenbrook, Jandabup and Neerabup into the Alkimos Wastewater Treatment Plant, thus finalising ongoing capital works vital for the future expansion in the northern districts of Perth.
Rob Carr was engaged by the Water Corporation to Design and Construct the Quinns Main Sewer Extension in Clarkson. During the design phase, Rob Carr was able to innovate significantly. In the first instance, by increasing the length of tunnelling for individual lines and totality, Rob Carr was able to reduce carbon dioxide emissions when compared to other pipeline construction techniques given the significant disturbance that would have been experienced if not using microtunnelling. In turn, changes to jacking pipe material led to a increase in local content by using locally manufactured DN1800 reinforced concrete jacking pipe (with PVC lining).
The DN1800 concrete PVC lined sewer traverses a total length of 1,931m. 1,531m will be installed via slurry pressure balanced microtunnelling using a Herrenknecht AVN1500 (including a DN1800 extension kit) combined with a VMT SLS guidance system. The tunnelling portion of the works consists of 4 tunnels in total, with the shortest tunnel 190m and the longest a 637m curved line on a 600m radius crossing the Joondalup rail line and the Mitchell Freeway during a planned rail shutdown over its 637m journey through sand and soft to hard pinnacle limestone. The remaining 400m length of pipeline was constructed via open trench and pipelaying techniques.
Other works successfully completed by Rob Carr consisted of in-situ and underpinned segment caisson shafts between 6 and 27m deep, 6 major concrete sewer maintenance structures, installation of 2 complex Vortex chambers up to 27m deep and 8.4m in diameter amongst other general ancillary construction activity.