North Thompson Sewer Pumping Station and Overflow Storage
Rottnest Island WA
Water Infrastructure & Pipelines
Rottnest Island Authority
- Completed
June 2022
September 2023
Project Overview
DM Civil was engaged in June 2022 by Rottnest Island Authority (RIA) for a contract to upgrade the existing North Thompson Sewer Pumping Station No 6 located on the foreshore at Bathurst Point.
The North Thomson Sewerage Pumping Station (SPS) No 6 is a critical asset. This is the final SPS following a series of three other interlinked stations, being Kingstown, Parker Point and the Tearooms (Hub) units. The SPS No 6 is approximately 40 years old and was reaching the end of its service life. The station had no emergency overflow storage to cater for a pump failure or power outage.
In October 2021, RIA undertook a condition assessment of the precast concrete wet well. In April 2022 the pump station wet well liner was stripped back and relined internally as forward works for this contract.
DM Civil was then able to undertake the main works including the mechanical, electrical, SCADA and bypass upgrades for the pumping station separable portion one and the construction of new emergency overflow storage as separable portion two.
Significant achievements and benefits
The construction of the EPPS Pipeline represented a synthesis of DM Civil’s capabilities. Namely, a diverse mixture of well-planned construction methodologies combined in order to carry out a complex project in a built up and difficult location.
The bulk of the works constituted HDD installation of the DN250 steel line pipe. This involved strategic positioning of HDD entry/exit pits for fabrication of the HDD pipe strings and in-house drafting of the HDD profiles to account for ground conditions, pipe bending and the constrained working areas. Despite drill shots up to 330m long, and in varying ground conditions, each shot was ultimately successful and high rates of productivity were achieved despite encountering groundwater, coffee rock and working amongst many live congested streets.
The open excavated portion of the works constituted an approximately 1km work front through the narrow suburban streets of Bayswater. Dealing with very sandy ground conditions, tight working spaces, well established trees and verges, re-designs and re-alignments, the construction team completed this portion of the works with minimal issues.
Pilot boring to install line pipe for high pressure gas applications is not a typical method utilised by our client ATCO Gas. However, pilot boring was successfully carried out across this project with 13 bores completed. This method proved most useful in areas too tight for HDD strings to be fabricated, but where trenchless installation was still necessary due to the presence of high-profile existing services and roads.
The success of the EPPS Pipeline project highlights the diverse, coordinated and high quality work that has made DM Civil a contender in the gas pipeline construction industry, and a favoured contractor amongst many clients.
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