Date
Client
Location
Tectonic’s Role
Services Provided
- Detailed geotechnical investigation
- Factual and interpretive reporting
Background
Due to the exponential regional population growth within and around Narangba, Unitywater were required to construct a new 7.3 km sewer main, along with upgrades and construction of new sewerage pump stations. The proposed installation will comprise 4 km of open trenching and 3.3 km of trenchless methodology (i.e. HDD, auger or thrust bore). One section will include over 2 km of HDD installation to depth of up to 38 m below ground level. The project will facilitate existing development within Narangba, Burpengary and southern parts of Morayfield, along with four new major development areas.
Scope
Tectonic were engaged to complete a geo-environmental investigation, including the drilling of 34 boreholes together with geotechnical and environmental laboratory testing. A combination of insitu testing was completed including standard penetrometer testing (SPT), dynamic cone penetrometer (DCP) and pocket penetrometer (PP) testing; among collection of over 100 m of NMLC rock core for strength and abrasion testing. Installation of groundwater piezometers and groundwater testing was also completed. The in-depth fieldwork program assisted in reporting on excavation and trenchless installations, temporary excavation shoring, groundwater levels and dewatering solutions, geotechnical design parameters, suitability assessments for excavated materials, and providing an acid sulfate soil management plan.
Challenges
Stakeholder and property liaison, including application for access and work permits through various government and private landholders. Engagement of a specialist traffic control firm to prepare to enable safe drilling access. Appropriate scheduling of required contractors was a major part of the successful completion of works. Four different types of drill rigs were used throughout the program to reach desired testing locations and enable collection of accurate results. Given the large linear distance of the project and the depth of some HDD under bores, various geo-environmental conditions existed across the investigation area., which exhibited different construction challenges and considerations.
