Bricks, Bends and Bypass – Design and Execution Challenges for the North Yarra Deviation Sewer Rehabilitation Project

Abstract

Melbourne Water’s North Yarra Deviation (NYD) sewer is a 90 year-old 2.6m diameter triple-brick lined sewer located under the Stony Creek backwash. The asset has been identified for upgrade for a number of years with recognition to the challenging environment to design and deliver the works. The design criteria required a risk-based approach due to the depth, poor ground conditions, high water table and incomplete knowledge of brickwork condition. Key challenges involved the management of sewer flows up to 2,200 L/s (up to 20% of Melbourne’s sewer volume), removal of mixed and contaminated silt and bricks, creating a safe working environment, lining 200m of 2.6m diameter sewer including bends with grouted spiral-wound HDPE technology, and rehabilitation of 5.5m diameter, 14m deep manholes featuring 80 year old penstocks, motorised gears and valves. A functional design was completed by KBR that determined the parameters and constraints for rehabilitation design to maximise the range of options for rehabilitation. John Holland-KBR Joint Venture lead detailed design and project delivery services including detailed definition, options selection and design and delivery of rehabilitation and bypass management with rehabilitation specialist Interflow and pumping specialists Welltech. Page 1 of 11 No-Dig Down Under 2019 Bricks, bends and bypass – design and execution challenges for the North Yarra Deviation Sewer Rehabilitation Project Matthew MacDonald, Andrew Hackett and John Monro