Transforming Agriculture in the Pilbara: Newman managed aquifer recharge (MAR) feasibility assessment

In the Newman region, DPIRD commissioned an assessment of the potential for managed aquifer recharge (MAR) near Newman using surplus water resulting from mine dewatering as the water supply for irrigated agriculture. The objectives of the MAR assessment were to: identify focus area for MAR feasibility assessment within the initial larger area of interest for MAR assess the viability of MAR with mine dewater near Newman to support development of irrigated agriculture, in keeping with national and state MAR guidelines identify key risks associated with MAR with mine dewater for irrigation supply, and identify knowledge/investigation required to adequately assess risks and define preventative measures to support approval for construction and commissioning (or complete pre-commissioning residual risk assessment). This report is presented in two parts. The first part describes the Fortescue River alluvial fan groundwater system and the data available for the risk assessment. Data was sourced from the WA Government and BHP Billiton along with that produced as part of the TAP project. For the completeness of this report, information previously reported by Schmid et al. (2022) and Donn et al. (2023) is summarised in this section. The second part uses the available data to assess the risks of potential MAR opportunities in the area. Due to data limitations, a broader scale regional risk assessment was undertaken rather than a site-specific risk assessment

Community management of onsite wastewater treatment systems- what they want in Mount Gambier, South Australia

Effective management of onsite wastewater treatment systems (OWTS) is important in preventing contamination of ecologically sensitive receiving environments, such as surface water and groundwater used for human consumption or contact. Householders play a key role in OWTS management, therefore inadequate householder knowledge of system function, inability to recognise signs of system failures and lack of understanding of maintenance requirements can increase the risk of system failure. A householder survey and community consultation process have been undertaken in conjunction with a biophysical effluent sampling program to reveal community understanding of OWTS, opinions on preferred management strategies, institutional arrangements and possible reactions to future financial costs to householders. Opinions from workshop participants and other stakeholders suggested their community wanted knowledge regarding OWTS functioning and maintenance, in particular, information on the use of suitable household chemicals to maintain treatment performance and continued research into contamination of groundwater sources by wastewater systems to better inform wastewater management strategies. Community participants were divided on the preferred administration and cost of maintenance, with some wanting to retain responsibility for maintenance arrangements by contracting specialised personnel and others suggesting local authorities should take responsibility

Assessing the Impact of Recycled Water Quality and Clogging on Infiltration Rates at A Pioneering Soil Aquifer Treatment (SAT) Site in Alice Springs, Northern Territory (NT), Australia

Infiltration techniques for managed aquifer recharge (MAR), such as soil aquifer treatment (SAT) can facilitate low-cost water recycling and supplement groundwater resources. However there are still challenges in sustaining adequate infiltration rates in the presence of lower permeability sediments, especially when wastewater containing suspended solids and nutrients is used to recharge the aquifer. To gain a better insight into reductions in infiltration rates during MAR, a field investigation was carried out via soil aquifer treatment (SAT) using recharge basins located within a mixture of fine and coarse grained riverine deposits in Alice Springs, Northern Territory, Australia. A total of 2.6 Mm3 was delivered via five SAT basins over six years; this evaluation focused on three years of operation (2011–2014), recharging 1.5 Mm3 treated wastewater via an expanded recharge area of approximately 38,400 m2. Average infiltration rates per basin varied from 0.1 to 1 m/day due to heterogeneous soil characteristics and variability in recharge water quality. A treatment upgrade to include sand filtration and UV disinfection (in 2013) prior to recharge improved the average infiltration rate per basin by 40% to 100%

Evaluation of Conceptual and Numerical Models for Arsenic Mobilization and Attenuation during Managed Aquifer Recharge

Managed Aquifer Recharge (MAR) is promoted as an attractive technique to meet growing water demands. An impediment to MAR applications, where oxygenated water is recharged into anoxic aquifers, is the potential mobilization of trace metals (e.g., arsenic). While conceptual models for arsenic transport under such circumstances exist, they are generally not rigorously evaluated through numerical modeling, especially at field-scale. In this work, geochemical data from an injection experiment in The Netherlands, where the introduction of oxygenated water into an anoxic aquifer mobilized arsenic, was used to develop and evaluate conceptual and numerical models of arsenic release and attenuation under field-scale conditions. Initially, a groundwater flow and nonreactive transport model was developed. Subsequent reactive transport simulations focused on the description of the temporal and spatial evolution of the redox zonation. The calibrated model was then used to study and quantify the transport of arsenic. In the model that best reproduced field observations, the fate of arsenic was simulated by (i) release via codissolution of arsenopyrite, stoichiometrically linked to pyrite oxidation, (ii) kinetically controlled oxidation of dissolved As(III) to As(V), and (iii) As adsorption via surface complexation on neo-precipitated iron oxides. © 2010 American Chemical Society