Moody Civil & Pipe successfully constructed a 9m deep sewage pumping station and associated works in an area with acid sulphate soils and a high groundwater table.
|PROJECT OVERVIEW||Construction of a 3.5m dia. 9m deep PE lined sewage pumping station in acid sulphate soils near Maryvale Rd, Mango Hill. This included construction of 50m of 2.1m dia. RC Pipe Emergency Storage Tank; 1045m of DN300 and 344m of DN375 Gravity Sewers; 1600m of DN400 PN16 PE100 Sewer Rising Main; associated electrical works, switchboard building; access road works and earth works, construction of block wall surrounding the pumping station. The truck water main consisted of 270m of DN300 dia PN16 PVC water main and a 180m DN400 PE100 PN16 directional drill underneath Freshwater Creek.|
|CLIENT||Moreton Bay Regional Council. Superintendent: MWH Australia Pty Ltd|
|LOCATION||Maryvale Road, Mango Hill, QLD|
|INDUSTRY SECTOR||Public utilities (urban)|
|INFRASTRUCTURE||Water pipelines, Gravity sewers, Sewer rising main, Sewage pump station & emergency storage|
|CONTRACT VALUE||$1.9 million|
|DATES||April 2010 to January 2011|
|SCOPE OF SERVICES PROVIDED||Planning and design|
• Option analysis
• Design of portions of work
• Service location
• Management of subcontractors
(Microtunnelling, Directional drilling, Traffic control, Electrical)
• Risk and budget costing
• Stakeholder and community liaison Environmental Management
• Translocation of protected flora
• Weed control
• Acid sulphate soils management
• Fauna management
• Siltation and erosion control
• Environmental management during construction in environmentally sensitive areas
|Installation & Construction|
• Pipe, pump & fittings supply (structures)
• SewerPro/SewerMax gravity sewer installation
• PVC & PE pipeline installation
• Hydrostatic & vacuum testing
• Deep shaft excavation
• Groundwater dewatering
• Sewage bypass pumping
• Sewer manhole construction
• Valve pit construction
• Poly welding (Butt, Electrofusion)
• Electrical conduit & pit installation
Civil & Mechanical Works
• Clearing and grubbing
• Civil & mechanical works for sewage pumping station
• Live connection work
|CHALLENGES||• Excavation in Acid Sulphate Soils (ASS) with a high groundwater table.|
• Pipeline Installation within the “NO‐GO Zone” of Power Poles greater than 3m in depth.
• Construction of pipelines and manholes in
“Salt Couch” areas (a protected flora). Moody developed translocation plans for its temporary removal and replacement.
• Due to the environmental constraints on the project, 420m of the gravity sewer and rising main had to be redesigned and realigned, as approval could not be obtained for open‐cut installation. Moody worked closely with Unitywater to develop options for construction of both of these. Several options were generated, estimated and risk ranked. Both pipelines were installed within a 5m easement.
|• During January 2011, the Brisbane area sustained heavy rain and flooding. As the majority of this project was in low lying areas, flooding occurred across the project site and halted production for 3 weeks.|
• Some of the pipeline was located within an Energex transmission line power easement. During the project construction, Energex were duplicating the existing transmission lines and towers. Moody worked closely with the transmission line principal contractor Transfield and Energex to schedule works to avoid conflicts and allow continual access along the easement for Transfield construction personnel.
• Working 8m deep in the road reserve of Maryvale Road, and management of excavated spoil.
|ACHIEVEMENTS||• Successful translocation and replanting of Salt Couch and reduction of construction footprint to minimise the amount of Salt Couch that was disturbed.|
• Restarting works safely following flooding in January 2011. No environmental harm occurred as a direct result of Moody construction sites, due to the erosion and sediment control put in place prior to this flood event. No rework was required either as we had prepared the sites for wet weather.
• Successful installation of 200m of DN600 gravity sewer, and 180m of DN400 PE water main, underneath Freshwater Creek without “frac‐outs”. This included an 8m deep launch shaft and management of PE pipe strings through residential areas, which involved liaison with developers.
|• Working with the community regarding full road closures, working through weekends to reduce the duration of road closures.|
• Saving trees that were important to residents, within the road reserve on the pipeline alignment, through use of Moody’s Horizontal Boring attachment.
• Working with Energex to obtain approval on construction methods to reduce the risk to the integrity of Energex assets. This involved development and manufacture of a horizontal boring attachment for our excavator, as well as design and RPEQ sign‐off of excavation & backfill methodologies.
• Successful completion of the project in approved timelines, allowing a sewage pumping station upstream to be decommissioned without delay.