Marsden Park Pressure Sewer
North West Sydney, New South Wales, Australia
The new Marsden Park wastewater pumping station and pressure main will transfer wastewater from the eastern portion of the industrial precinct to the existing Riverstone Carrier System. Diona successfully fabricated and constructed the first dual barometric loop on the Sydney Water network under the project scope.
Marsden Park Industrial Precinct in the North West Growth Centre was rezoned for development of a 205 hectare master planned employment precinct and about 1,200 new dwellings. To meet demand for essential services to North West Sydney, Sydney Water have planned, designed and continue to build, operate and maintain water and wastewater infrastructure to service the area as it develops.
Diona were engaged to deliver the submersible pumping station (SP1173), pressure main, dual barometric loop and gravity main draining to the Riverstone Carrier.
Diona carried out the construction of the pressure main and all appurtenances from SP1173 pumping station to the barometric loop. This required a combination of open trench and bored construction of 2.4 kilometres of DN450 polyethylene pipe, ranging in trench depth between 2.5 metres to 4.5 metres. Three sections were auger bored under South Street, Bells Creek and Grange Avenue totalling 160 metres.
Pipe jointing was primarily undertaken by butt welding and fusing the polyethylene pipes together. Appurtenances on the pressure main included eight scour points, five manual air valve and three automatic air valves all contained within concrete pits. Three 14 metre high vent shafts were constructed to ventilate the automatic air valve pits to ensure odour control for residents.
The pressure main which connects into a dual barometric loop was fabricated and constructed by Diona. The dual barometric loop structure consists of four linked stainless-steel vertical pipes standing at just over 20 metres above ground level. The above ground stainless steel pipe work is stood on and connected to a concrete discharge maintenance hole integrated structure with associated bypass pipework, stainless-steel vent line and a 14 metre vertical educt vent shaft.
From the discharge maintenance hole, pumped flow from SP1173 pump station and pressure main will transition to gravity flow. The gravity flow is taken by 100 metres of DN750 GRP gravity sewer pipe installed by Diona and connected into the existing DN900 Riverstone Carrier. The gravity main intercepts the existing carrier with a newly constructed maintenance hole over the carrier.
Many challenges were overcome during the delivery of the project, particularly relating to heritage and environmental sensitivities within the work corridor. Diona demonstrated detailed planning and execution to overcome these challenges in line with the project specific environmental management plan, method statements and risk assessments.
Challenges included: opening ground within flood zones and flood channels and ensuring containment of spoil and sediment; unexpected finds of asbestos contaminated spoil on three separate occasions with safe clearance and disposal to suitable waste facilities; containment and removal of all groundwater off site due to high salinity content to ensure no irreversible damage to surrounding vegetation and habitat; working within 15 metre work corridors to reduce project footprint and vegetation removal and trenching through Eastern Creek without impact to the local fish habitat.
Diona successfully delivered the works to Sydney Water timeframes and ensured wastewater servicing to new development and dwellings within the Marsden Park Industrial Precinct. The adjacent environment was protected throughout the project and reinstatement exceeded the site conditions prior to construction.
This was a complex project with all fields of Diona coming together, from technical structures like the barometric loop, to the 15 metre environmental construction corridor and surrounding aboriginal heritage confinements.
The wastewater alignment directly affected approximately 50 properties, and indirectly double that amount, with work carried out both within private properties and council verge. Diona worked closely with all directly impacted community stakeholders to ensure the best possible outcomes for both the client and their customers.
Additionally, the project team also considered the environmental impacts by installing a turbidity curtain in Eastern Creek to catch waste and sediment floating down the creek.