The Utah Point Berth Project (UPBP) at Port Hedland in northern Western Australia in-volved the development and operation of a common user bulk export facility, primarily to serve the mining industry in the Pilbara region.
Utah Point works with a number of emerging commodities producers of Western Australia and provides a new facility for existing Port Hedlands exporters. The throughput of these facilities is expected to be approximately 17 million tonnes per annum of various bulk products but predominantly iron ore and manganese.
For the construction of the main stockyard and access roads at Utah Point, extremely soft clay soils (such as within the area’s mangrove wetlands) needed to be overcome.
The clay foundation soil was highly plastic with undrained shear strength of approximately 10kPa. Embankment heights up to 5m, combined with exceptionally high live loads (e.g., 100 tonne ore loaders) challenged the design team to find an economical method for embankment support.
BBG Bauberatung Geokunststoffe GmbH & Co. KG selected a laid geogrid made of stretched, monolithic polyester (PET) flat or pro-file bars with welded junctions (Secugrid®) to meet this demanding application. Long-term embankment stability and sup-port was essen- tial; NAUE Secugrid® fit the specification perfectly.
The polyester (PET) Secugrid® 400/40 R6 & Secugrid® 120/40 R6 geogrids were designed into the embankments such that the vertical loads exerted by the embankment on the soft foundation soils were transferred into the horizontal geogrid layers. Interestingly, the mangrove sub-grade was so soft that installing the reinforcement geogrids rolls was itself quite a challenge. Conventional heavy equipment could not be parked around the site. Swamp dozers and specially designed ‘low pressure’ buggies were brought in to deploy the geogrids across the stockyard so that enough bearing strength could be achieved for the rest of the site’s construction.
Ertech Pty Ltd. & Bierty Pty Ltd. installed approx. 500,000m² of Secugrid® over the Utah Point’s work zone.
Not only the site successfully came online, but the Port Hed-land Port Authority and PINC Group (Project Management) even won the Australian Engineering Excellence Award in the “Resource Development” Category for the Utah Point Multi-User Bulk Export Facility project.
Now in full operation, UPBP’s stockyard isn’t supported by just geogrids; the site is also protected by geosynthetic clay liners (GCLs). The stockyard serves as an essential pre-export storage zone for mined ores (e.g., chromite, manganese). As leachate from the ore piles is a potential threat to the mangrove wetlands, a GCL barrier protects the soils.
For the critical leachate containment area, Global Synthetics Pty Ltd. supplied and Ertech installed nearly 100,000m2 of NAUE Bentofix® GCL at a minimum 300mm below the finished floor level. The high-swelling powder sodium bentonite core of Bentofix® and the durable, needlepunched nonwoven geotextile protection layers provide a level of barrier protection that outperforms significantly thicker compacted clay liners in service life, impermeability, and project economics.
Utah Point rests on firmer ground, thanks to Secugrid®; and the site provides exemplary environmental security, thanks to Bentofix®.