THE PROJECT

The management of large volumes of excess water from dewatering operations is critical at many iron ore mines in the Pilbara.  Managed aquifer recharge (MAR) is commonly used as a means of minimising environmental impacts and storing water for future use.

Rockwater was sub contracted by GHD to develop MAR Engineering Standards and Specifications for BHP Iron Ore, one of largest iron-ore producers in the Pilbara.

Specific injection bore designs and specifications were developed for the major aquifer types at BHP’s operations.  Construction specifications for injection bores and monitoring bores were provided, including materials specifications, grout-seal requirements and filter-pack specifications.  Monitoring and reporting protocols, and bore-clogging trigger levels and actions were also developed.

The MAR project involved extensive consultation with GHD and BHP.  It represents a successful application of Rockwater’s specialist knowledge for site practitioners and project planners.

• MAR injection bore design for main aquifers
• MAR monitoring bore design
• Gravity-fed MAR design
• Pressure-fed MAR design
• Clogging assessment design and development of clogging trigger levels
• Monitoring criteria 
• Equipment section guidelines
• Summary MAR Specifications

THE PROJECT

Managed aquifer recharge is being considered for water supply in the Myalup Irrigated Agricultural Precinct.  Allocation limits and salinity concerns at Myalup prohibit increased extraction from the Superficial Aquifer.

An option of increasing groundwater availability that is being assessed is to seasonally recharge the aquifer up to 26 GL/annum of water from various surface water sources.  A trial is planned involving infiltration of up to 1 GL/a from a nearby drain.

Rockwater was engaged by the Department of Primary Industries and Regional Development to perform Stage 1 and MAR risk assessments for the MAR scheme at Myalup.

The next step is to perform a small-scale trial using an infiltration basin.  Rockwater designed the MAR trial and continues to provide regulatory liaison.

• Geological and geophysical interpretation
• Hydrogeological assessment
• Risk assessment according to national MAR guidelines
• Regulatory liaison
• Data compilation and assessment

• Water quality analysis
• Pilot MAR trial
• Infiltration testing

THE PROJECT

Residential development has driven an interest in artificially maintaining water levels in Perry Lakes, at Bold Park.  The lakes were naturally seasonal, but declining groundwater levels in the Surficial Aquifer since the 1960s have led to the lakes now being mostly dry.

Various methods of enhancing water levels in the lakes have been modelled by Rockwater, including lining the lake bed with clay, and using infiltration galleries to recharge water from the nearby Subiaco Waste-Water Treatment Plant.

In 2020, Rockwater was engaged by the Town of Cambridge to model how much water from the Herdsman Main Drain would be needed the to maintain water levels at Perry Lakes at a prescribed level.

To develop the Perry Lakes model, we performed a lake-bed bathymetric survey using a DGPS and a small remote-controlled boat equipped with a sonar.

Rockwater has a 5-year partnership with the University of Australia for the supply and development of the remote-controlled boat equipped with a sonar.  The system is also capable of surveying small dams and flooded pit voids.

• Field investigation reporting
• Hydrogeological assessment
• Groundwater modelling

• DGPS surveys
• Bathymetric survey with remote controlled boat
• Lake bed survey

THE PROJECT

The City of Greater Geraldton needed to formalise licensing of recovered wastewater for the irrigation of public open space.  A significant increase in allocation from the Superficial Aquifer or deeper aquifers was not possible.

Approval was sought from the Department of Health for the City to use water supplied by the Water Corporation that had been recovered from around the Geraldton No. 2 Waste Water Treatment Plant.

Rockwater liaised with the Water Corporation and Department of Health to prepare a Recycled Water Quality Management Plan for the MAR project.  We provided direction to ensure compliance with the plan’s safety and sampling guidelines, and continue to prepare regulatory reports on an annual basis.  We also provide hydrogeological advice on the operation and renewal of the City’s irrigation bores, as required.

• Annual compliance reporting
• Recycled Water Quality Management Plan
• Approvals from the Department of Health
• Implementation planning for additional recovery bores

• Water level monitoring
• Water quality sampling

THE PROJECT

The City of Mandurah is developing a large-scale waste-water reuse scheme for irrigation of the northern sector of its public open space.  It is planned to recover up to 2 GL/annum of water from the Gordon Road Waste Water Treatment Plant, which recharges water to the Superficial Aquifer.

In 2016, Rockwater completed a hydrogeological review and risk assessment for the project following the national MAR guidelines. This was used to develop reuse scheme options.

In 2018-19, we designed and supervised the construction of eight monitoring bores to measure water levels and water quality in the groundwater mound created by the waste-water treatment plant.

A groundwater model was then used to determine a sustainable volume that could be allocated to the City, and the best methods of its recovery and distribution.  It is anticipated that scheme will be implemented following approval by the regulator.

• Geological and geophysical interpretation
• Field investigation reporting
• Hydrogeological assessment
• MAR risk assessment
• Bore design
• Drilling supervision
• Groundwater modelling
• Regulatory liaison

• Sonic drilling for improved core recovery
• Monitoring bore construction
• Down-hole induction logging for salinity profiling
• Permeability tests

THE PROJECT

The Department of Mines, Industry Regulation and Safety (DMIRS) is investigating the feasibility of storing carbon dioxide within the Lesueur Sandstone at its Southwest Geosequestration Hub.

In 2014-2015, two stratigraphic holes (Harvey 2 and 3) were drilled to up to 1,750 m depth using diamond coring methods, and a third bore (Harvey 4) was drilled to 1,800 m depth by mud rotary.  This provided important information of the ability of the Eneabba and Yalgorup formations to isolate carbon dioxide injected into the underlying Lesueur Formation.

Rockwater was sub-contracted by the lead drilling contractor (DDH1) to provide geological interpretation, sample collection and project management during drilling of the three holes.  This included daily and weekly progress updates to DMIRS.

In 2020, Rockwater provided CSIRO (current operator the geosequestration laboratory) with advice and supervision of bore workover and injection testing.  The workover used fiber optic sensing equipment installed down the hole, and a pressure transducer at the reservoir level, to monitor well efficiency improvement during the workover.

• Geological and geophysical interpretation
• Field investigation reporting
• Bore remediation risk assessment

• Down-hole geophysics surveys
• Core logging
• Mud-rotary bores
• Pumping tests
• Injection tests
• Bore remediation
• Clogging assessments
• Fiber optic distributed sensing