Engineering Depth for Land, Water and Infrastructure.

Project Summary Recommissioning of the Pukekohe municipal supply which abstracted water from Hickey's Spring and two deep Kaawa aquifer bores. Services Provided Conceptual and numerical groundwater modelling of effects for 1,509,000m³/yr take for Watercare from three production bores. Quantitative streamflow analysis to determine flow available for abstraction and low flow requirements in the Whangapouri Stream, including statistical analysis of low flow recurrence intervals. Preparation of Assessment of Environmental Effects (AEE). Project Conclusion Successful consenting of the water take consent as part of Watercare's response to the 2020 drought conditions.

Project Summary Deriving the groundwater abstraction availability for the Franklin Deep Waitemata Aquifer in accordance with the Auckland Unitary Plan. Services Provided Development of a conceptual model for the aquifer; including groundwater flow paths, recharge and discharge zones, and aquifer boundaries. Review of existing management area boundaries. Calculation of groundwater availability for each management area. Project Conclusion The successful determination of aquifer abstraction availabilities for four separate groundwater management areas.

Project Summary Earthtech has assisted with the bridge replacement by carrying out geotechnical design of the new Ohinekaua Stream Bridge. Ground conditions at the site were complex, including a thick layer of weak and compressible peat and clay, and deep liquefaction effects. Through specialist testing and analysis, and working closely with the project team, we were able to provide a practical solution which saved the project millions of dollars in foundation and ground improvement costs. Services Provided Organisation of sCPT testing to define ground conditions. Specialist liquefaction susceptibility analysis based on recent research and considering the requirements of current design standards. Specialist assessment of consolidation settlement effects. Bridge pile design including negative skin friction. Project Conclusion This project showcases how…

Project Summary The development of a >500,000m³/yr groundwater take for irrigation, frost protection and spray use for a large kiwifruit orchard. The water is supplied from two boreholes tapping the deep confined fractured ignimbrite Mamaku aquifer. Services Provided Desktop study of hydrogeological/hyrological setting. Drilling liaison and pump testing. Assessment of Environmental Effects (AEE). Development of a numerical groundwater model to assess groundwater pumping effects on surface water. Council liaison and iwi consultation. Project Conclusion This project secured groundwater abstraction rights, demonstrating that the proposed take aligns with sustainable allocation limits and regulatory requirements.

Project Summary The development of a dairy irrigation supply consisting of a groundwater take of 406,800m³/yr, from two production bores >100m deep which tap the Awhitu Peninsula Kaawa aquifer, and a run-of-stream take of 465,700m³/yr. Services Provided Desktop study of hydrogeological/hydrological context. Drilling liaison and pump testing. In-stream flow monitoring with a weir. Assessment of Environmental Effects (AEE). Saline Intrusion monitoring. Project Conclusion This project secured groundwater and surface water abstraction rights, demonstrating that the proposed takes align with sustainable allocation limits and regulatory requirements.

Project Summary Earthtech carried out detailed geotechnical investigations for the four-lane bridge, associated on- and off-ramps, and road alignments. This included the design of deep soil mixing ground improvement to address liquefaction effects, retaining walls, earthworks, stability assessment adjacent to live roads and nearby gully, and dewatering for buried services construction. The scope of work included construction inspections and producer statement (PS4) signoffs. During the course of the project, we formed effective working relationships with the project team. Services Provided Detailed geotechnical investigations, including seismic testing. Geotechnical design of bridge foundations, retaining walls, ground improvement, slope stabilisation works, preloading to address ground settlement effects, dewatering and groundwater control works, and many more. Contractors' temporary works, including haul road formation. Specialist…

Project Summary Elevated artesian groundwater pressures coupled with overhead power lines, created challenging conditions for bridge pile construction. Working with the project team, Earthtech provided a dewatering bore design solution to depressurise the artesian groundwater levels. Timeframes were very tight, meaning that the dewatering design, consenting and dewatering bore construction stages significantly overlapped. The project was delivered on time, and Earthtech assisted with real-time groundwater level control and monitoring during piling activities. Services Provided Groundwater analysis and design of a bore-field dewatering system. Preparation of the Assessment of Environmental Effects and consenting of the groundwater take (dewatering) and diversion activities. Ongoing involvement and contractor support during dewatering and piling activities, including assisting with the setup of groundwater level alert and…

Project Summary Earthtech has been assisting these clients with canal subdivision developments since the 1990s. Across these projects, we have supported the developer through the design and construction of multiple subdivision stages, including associated retirement villages, commercial buildings, and road access bridges. Services Provided Geotechnical investigations to define ground and groundwater conditions, including machine boreholes, CPT testing and hand augers. Geotechnical subdivision design, including the design of preloads to address consolidation ground settlement effects, ground improvement to manage liquefaction effects, slope and canal edge stability and stabilisation, and geohazard identification. Inspections, verification testing and general advice during construction. Preparation of Geotechnical Completion Reports and geotechnical producer statement sign-offs. Project Conclusion These projects stand as a testament to the long-standing care…