Jigalong Community Wastewater Pumping Station and Treatment Plant

May 2023

DM Civil is currently engaged in three regional projects in Western Australia and another in South Australia.

We are now well underway with our project at Jigalong Community, 2 hours east of Newman, with the first swing complete. The scope of works is driven by the fact that the existing wastewater treatment ponds to the west of town are failing and are no longer serviceable but cannot be taken offline for sufficient time to be refurbished. The new ponds being constructed by DM Civil are some 2km to the east of town.

The Jigalong contract is unique in its remote location in a small ‘dry’ community with none of the usual recreational facilities associated with a normal regional job site or even a water body or coastline. The DM Civil crew is restricted to a single house with shared messing and ablutions and the need to cater for their own meals. Night time security is an issue and compliance with cultural heritage protocols is always front of mind.

We express our appreciation to the crew members for their efforts to work what could be described as rather restricted conditions on long shifts and long rosters. Our project engineer, has provided excellent leadership with organising crew activities, liaison with the community CEO and being able to concentrate on the technical task at hand. His work has continued on break to ensure continuity of communication with the client.

Our initial focus has been the setup of facilities to allow the scope of works to proceed. Construction water had to be sourced from an existing bore some 20km from the site in a borefield that also supplies the community. The Little Sandy Desert is obviously a particularly dry location and controls on abstraction rate and daily quantity are closely monitored. Our remaining 50kL water tower is set up at Bore 2/85 to allow low constant flows to provide overnight filling. Water is essential for the earthworks at the wastewater ponds to provide optimum moisture content for the soil to be placed and compacted in the pond embankments.

The soil at the wastewater ponds site is extremely fine and of a high plasticity. This is unsuitable for embankment construction on its own. We have therefore mined in excess of 1,000 cubic metres of a coarser fill material from a location some 10km away adjacent to the water supply break tank, part way to the Bore 2/85 water source. The water has been transported to site and is being blended in a 1 to 3 ratio with the stockpiled insitu material, and moisture conditioned with the imported water to produce a compliant material suitable for pond wall construction. This was proven with a trial section which was tested by our geotechnical consultant and witnessed by the client.

As a part of the scope of works, the existing pumping station is to be refurbished by installing new pumpsets including electrical switchboards and controls. A new pressure main will convey the wastewater to the new ponds when completed and commissioned. This has already been partially completed. The original sequencing of pump renewal involved an iterative process of replacing and testing one pump at a time and testing before proceeding to the next. DM Civil provided a value adding solution of installing a fully automated bypass pump set to take the wet wells completely off line to allow for full mechanical and electrical refurbishment to take place in isolation and without risk of encountering a situation that delayed full operation of the community wastewater facility.

Another positive initiative introduced by DM Civil was the recognition that the road bridge on the route to the break tank borrow area had load limiting signage not previously considered by the client when allocating haul routes. Sam E. and Ben S. notified the client and provided solutions for a detour around the bridge or to reconfigure the truck combinations to keep under the load limits. The client expressed their appreciation to DM Civil as a proactive contractor offering advice on potential issues and providing solutions to ensure continued production.

A further positive initiative for the contract has been the employment of a local resident aboriginal in our crew who provides another channel of communication with the community.