Preliminary reading and simplified assessment criteria (Section 4.2) Chapters 1–4 Stage 1 Collect available information and entry-level assessment Source water available? Aquifer present, and storage and recovery allowable? Acceptable use for recovered water? Planning requirements addressed? Assess likely degree of difficulty Chapter 4, Appendix 1 Investigations to assess viability and risks Source water and groundwater sampling and analysis Hydrogeological studies Catchment studies Basic groundwater modelling and geochemical evaluation Appendix 2, Chapters 5 and 6 Stage 2 Maximal risk assessment Estimate maximal risk Evaluate uncertainty Chapter 5, Appendixes 4–7 Identify preventive measures needed for validation (eg operational procedures, critical control points, contingency plans) Chapters 5 and 7 Residual risk assessment – validation stage Forecast residual risk of validation Chapter 5 Construct project and perform trials; commissioning to validate preventive measures Appendix 3 Stage 3 Residual risk assessment Evaluate residual risk and uncertainty with preventive measures in place Chapter 5 Stage 4 Project operation and verification Management plan Operational monitoring Chapters 5–7
than one hazard. The lists given in the table are not definitive. Depending on the particular project, other critical control points and preventive measures may be more appropriate. Education and training are important components of implementing and maintaining prevention measures. Table 5.3 Summary of preventive measures and critical control points for managed aquifer recharge Preventive measures Description Critical control point Exclusion barriers — preventing entry Hazard source control Selection or management of water sources No before recharge (eg catchment, recycled water, roof runoff, stormwater) Intake levels Exclusion of floating hazards by maintaining No intake levels below the water surface Exclusion of water that does not meet critical limits Continuous monitoring of indicator variable, to provide feedback to divert water flow or stop recharge when critical limit is exceeded Possibly: depends on the hazard, associated risk prevented and monitoring system Exclusion barriers — removing hazards Residence time in the soil or aquifer Travel distance in aquifer Attenuation of all human pathogens and selected organic chemicals Travel distance (between recharge and recovery) chosen to provide a minimum residence time under the range of operating conditions Yes: the system needs to provide required residence time; recovery rate is restricted to ensure adequate time between recharge and recovery No: component of system design Treatment processes Concentration of specific hazards decreased before recharge or on recovery Possibly: at the point of recharge and/or recovery; depends on the hazard and effect on the specific environmental endpoint
Table 5.5 Criteria, controls and monitoring to mitigate pathogen hazards in relation to the stages of risk assessment Acceptance criteria Entry-level assessment and simplified assessment • Source water for recharge has low risk of pathogen contamination • Exposure to recovered water is no greater than to the source water used for recharge • End use for recycled water and environmental values of aquifer exclude drinking water Maximal and precommissioning residual risk assessment • Source water has a residual risk <10–6 DALYs per person per year without reliance on aquifer for treatment or dilution (eg use of 95th percentile pathogen numbers); or in the absence of data, use values from other guidelinesa to determine DALYs Residual risk assessment (operational) • Confirm residual risk <10–6 DALYs per person per year for water recovered (by project and by any third party), based on additional data collection if dependent on treatment in the aquifer Preventive measures • water protection • Removal using treatment processes • Residence time in the soil and/or aquifer • Reducing exposure • As per precommissioning residual risk assessment Validation monitoring Verification monitoring • that the process control and operational monitoring correlate with pathogen inactivation; provide ongoing assurances that the attenuation zone is operating effectively, and that water of an appropriate quality is being produced. This includes setting critical limits to differentiate between acceptable and unacceptable performance. na na • Monitor pathogens or indicator organisms in recovered water and in observation wells at edge of attenuation zone • Achieve the specified log removal to achieve acceptance criteriab t n n n S
Table 5.6 Criteria, controls and monitoring to mitigate inorganic chemical hazards in relation to the stages of risk assessment Acceptance criteria Entry-level assessment and simplified assessment • Major ion chemistry concentration meets the environmental target for the aquifer • Low risk of mobilisation from the aquifer Maximal and precommissioning residual risk assessment • Inorganic chemical concentrations in source water meet target for beneficial use • Decision tree in Appendix 7 suggests metal mobilisation is unlikely to be a problem • Geochemical modelling shows release from aquifer is unlikely to produce inorganic chemical concentrations above target values Residual risk assessment (operational) • As per precommissioning residual risk assessment Preventive measures • to Sections 6.1 and 6.2 for operational management • pH and redox (Eh) adjustment in source water • As per precommissioning residual risk assessment, plus – source control – treatment of source water to minimise release from aquifer – post-treatment of recovered water Validation monitoring • inorganic chemical concentrations in – source water – groundwater in storage zone (observation well/s) – recovered water • Evaluate aquifer physiochemical and redox conditions Verification monitoring • Not applicable at project scale (undertaken at regional scale) • chemical concentrations in recovered water and at margin of attenuation zone R t e e n i D D
the Phase 1 guidelines). This is because the enrichment or addition of salts from natural or anthropogenic processes in water transported through a rural or urban catchment increases its salinity levels. Salinity levels in groundwater range from fresh to highly saline. Infiltration of shallow saline groundwater into leaky sewers can substantially increase the salinity and sodicity of sewage effluent, rendering it unfit for recycling via managed aquifer recharge unless it is treated or blended. 5.3.3 Management of salinity and sodicity Management controls include preventive measures such as: • catchment water-quality management and source control (to minimise salt export and remove or mitigate point sources of salinity, where viable) • source water selection • site selection to target aquifers that minimise risk • pretreatment or post-treatment (desalination) • shandying of recovered water with alternative, lower salinity sources (shandying is the addition of one water source to another). 5.3.4 Mitigation of salinity and sodicity hazards in relation to stages of risk assessment General criteria for assessing the appropriate level of management for salinity and sodicity hazards are provided in Table 5.7. Table 5.7 Criteria, controls and monitoring to mitigate salinity and sodicity hazards in relation to the stages of risk assessment Acceptance criteria Entry-level assessment and simplified assessment • Source water for recharge <500 mg/L TDS • Source water of better quality than ambient groundwater Maximal and precommissioning residual risk assessment • Low anticipated mixing leading to acceptable recovery efficiencies • Low risk of mobilising salt stored in the soil profile or in aquifer mineral deposits • Low probability of undesirable off-site impacts Residual risk assessment (operational) • As per precommissioning residual risk assessment criteria, based on validation monitoring during commissioning and further modelling Preventive measures na • Refer to Section 6.2 • Refer to Section 6.2
Table 5.7 (continued) Entry-level assessment and simplified assessment Maximal and precommissioning residual risk assessment Residual risk assessment (operational) Validation monitoring na na • Determine salinity and sodicity of recharge and recovered water, supported by volumetric inputs and outputs to allow a salt mass balance • Quantify impacts on receiving ecosystems, plus monitoring and investigations to define the level of residual risk • Validate solute transport model for predicting recovery efficiency and residence time • Model density effects on recovery efficiency, if needed Verification monitoring • Not applicable at project scale na • Refer to Section 6.2 Operational monitoring at regional scale) • Estimate or measure annual injection and recovery volumes • of recovered water na • Determine salinity of recharge and recovered water, supported by volumetric inputs and outputs to allow a salt mass balance • Refer to Section 6.2 na = not applicable; TDS = total dissolved salts. 5.4 Nutrients: nitrogen, phosphorus and organic carbon This section discusses nitrogen and phosphorus — recognised as environmental hazards for water recycling (NRMMC–EPHC–AHMC 2006) — and organic carbon, an important nutrient in relation to microbial processes in the subsurface. M
Table 5.10 Criteria, controls and monitoring to mitigate organic chemical hazards in relation to the stages of risk assessment Acceptance criteria Entry-level assessment and simplified assessment • Organic chemicals unlikely in source water at concentrations that would exceed acceptable concentrations for environmental values of aquifer or intended end uses • Unlikely to be formed in the subsurface (ie no disinfection) Maximal and precommissioning residual risk assessment • Any organic chemicals present in source water (eg using mean of measured concentrations to account for dispersiona in aquifer) or formed in the subsurface (eg disinfection byproducts) are at, or attenuate to, concentrations that meet environmental values for aquifer beyond attenuation zone and in water recovered for use Residual risk assessment (operational) • As per precommissioning residual risk assessment Preventive measures na • Source control • residence time in soil or aquifer, or treatment • Reduce disinfection byproduct precursors or change the disinfection process • As per precommissioning residual risk assessment Validation monitoring • (hazard) and biodegradable organic carbon (cosubstrate) concentrations in – source water – attenuation zone observation well/s – recovered water • Analyse minimum period of aquifer storage using ‘natural’ or introduced tracers • Evaluate physicochemical and redox conditions m P t e D
Table 5.13 Criteria, controls and monitoring to mitigate pressure, flow or volume-related hazards in confined and semiconfined aquifers in relation to the stages of risk assessment Acceptance criteria Entry-level assessment and simplified assessment • Analytical models predict no other wells to be artesian • Wells constructed and completed according to well completion permit Maximal and residual risk assessment • Calibrated model of injection and recovery well rates of flow, cumulative recharge and discharge volumes, and pressures for proposed trial (Stage 3) • models predict defined maximum and minimum heads in injection well, to be achieved by pump selection and placement • Acceptable predicted maximum and minimum heads in other wells as a result of operation, with respect to – aquitard protection – subsidence – leakage losses – head and water-quality changes in other aquifers (from calibrated model) • No wells in zone with large head changes intersect the target aquifer, have multiple completions or are known to be poorly completed • Recharged water is confined to target storage zone and predicted upward and downward leakage is negligible • Predicted land subsidence is negligible Residual risk assessment (operational) • As per precommissioning residual risk assessment, with confirmation, based on field and laboratory measurements, informing hydrogeological and geotechnical evaluations of uncertainties identified in precommissioning residual risk assessment • To include quantified criteria (eg bursting pressure, subsidence, and head changes in observation and other wells) • Modelling and trials reveal no adverse effects on other aquifers or connected ecosystems
Table 5.13 (continued) Entry-level assessment and simplified assessment Maximal and precommissioning residual risk assessment Residual risk assessment (operational) Preventive measures • Pump selection and placement • seals on wells that are to become artesian • Backfill wells that intersect the target aquifer and are poorly completed or have multiple completions, where the rate of vertical flow is likely to adversely impact water quality in the target storage zone or water quality and levels in other aquifers • Restrict injection and recovery rates • Construct piezometers to give early detection of leakage • As per precommissioning residual risk assessment, with refined identification of – artesian wells – poorly completed wells – bursting pressure – aquitard collapse or consolidation • Where real-time adaptive management is required, use feedback control systems (to change pumping rates or shut down pumps) and telemetered messaging systems Monitoring • Estimate or measure seasonal or annual injection and recovery volumes • Perform pumping test and down-hole flow metering to evaluate transmissivity and storage coefficient for the target aquifer at the injection well, and to predict fate of recharged water in the aquifer • Monitor observation well in the overlying aquifer adjacent to the injection well, and in the target aquifer, at a small radius. This will provide early warning of artesian conditions in other wells, potential for subsidence or aquitard failure • Also monitor heads in well at margin of attenuation zone (if a different well) to verify projected head changes in aquifer • Implement groundwater- level monitoring as early as possible before commissioning, to generate background data • As per maximal risk assessment, plus monitoring at critical control points • Monitor subsidence if warranted by geotechnical evaluation and head • Monitor control system to detect potential hydraulic failure, for example – burst aquitard – excessive leakage – subsidence – excessive preferential flow – lack of flushing d s
Table 5.14 Criteria, controls and monitoring to mitigate pressure, flow or volume-related hazards in unconfined aquifers in relation to the stages of risk assessment Acceptance criteria Entry-level or simplified assessment • Infiltration site is not on sloping land, adjacent to surface or dependent or underlain by known shallow layers • At site, depth to watertable exceeds 8 m in an urban area or 4 m in a rural area with no nearby • site is not in or adjacent to a landfill or known site • Reservoir release rate is restricted to avoid causing a drowning hazard or excessive scouring Maximal and precommissioning residual risk assessment • Groundwater model is calibrated based on adequate data • Field data on soil profile down to the aquifer, aquifer properties and calibrated groundwater modelling show that the predicted shallowest depth of watertable, outside the basin or gallery, is sufficient to not cause – waterlogging – soil salinisation – salt-damp – foundation movement – structural damage – flooding of cellars or other infrastructure • Aquifer’s capacity can store volume intended, meeting criteria above • Existing land uses and waste management in the area have low risk of contaminating groundwater and inhibiting intended uses of recovered water Residual risk assessment (operational) • Confirmation of achievement of precommissioning residual risk assessment criteria, based on additional field and laboratory measurements and validated groundwater model • Trials and modelling reveal no adverse effects on other aquifers, connected water bodies or ecosystems ecosystem
Table 5.14 (continued) Entry-level or simplified assessment Maximal and precommissioning residual risk assessment Residual risk assessment (operational) Preventive measures • Install overflow diversion to prevent excessive recharge heads or volumes • use of pumps for • See Section 6.1 concerning clogging management • Restrict volume and rate of recharge to periods appropriate to the local conditions (eg annual, monthly, daily) • Drill, slot or rip subsurface semipermeable layers to allow infiltration without surface waterlogging • Relocate infiltration site and redesign separation distances between recharge facilities and recovery locations, and between potentially polluting land uses and waste management practices in the area and the managed aquifer recharge operation • Construct piezometers and observation wells to allow early warning and assist in model calibration • Increase drying time in basins or galleries between infiltration events, to allow groundwater mound to subside • Where real-time adaptive management is required, use feedback control systems (to change pumping rates or shut down flow) and telemetered messaging systems Validation monitoring • or galleries • Monitor soil moisture, suction and piezometric levels in unsaturated zone beneath basin and gallery, to discriminate between causes of any detected reduction in infiltration rate • Monitor function of connected ecosystem if warranted by the level of impact event a M t b
Table 5.14 (continued) Entry-level or simplified assessment Maximal and precommissioning residual risk assessment Residual risk assessment (operational) Verification monitoring • and recovery rates of – flow – cumulative recharge and discharge volumes – watertable elevation • Monitor observation well in target aquifer at critical control points (beneath and adjacent to the recharge basin or gallery), and at a well further away, to provide early warning of excessive mounding and discriminate between causes • Monitor control system to detect potential failure Operational monitoring na = not applicable. • Estimate or measure seasonal or annual injection and recovery volumes • Implement groundwater level monitoring as early as possible before commissioning, to generate background data • See verification monitoring and validation monitoring above. Continue monitoring until unsaturated zone and aquifer behaviour is well understood. Ensure that flow and water-quality monitoring are coordinated 5.9 Contaminant migration in fractured rock and karstic aquifers In fractured rock aquifers, most water flows through cracks in the rocks, and thus may only interact with a very small percentage of the rock mass. The effective porosity of fractured rock aquifers is much less than for aquifers in which flow is predominantly through interconnected pores throughout the porous medium. Water is conveyed through connecting fractures, and may zigzag through aquifers in three dimensions. Hence, the water injected into a fractured aquifer will travel further from the ASR well than the same volume would travel in a porous aquifer. The distribution of recharged water is therefore much more difficult to predict, which has implications for a M t
Table 5.17 Criteria, controls and monitoring for groundwater-dependent ecosystem protection in relation to the stages of risk assessment Acceptance criteria or simplified • Avoids recharge in close proximity to sensitive • Avoids aquifer with shallow watertable for recharge and recovery of water Maximal and residual risk • shows that hydraulic head in dependent ecosystems are within historical range or closer to historical range than they would be without the project, or that heads do not fall below minimum levels for ecosystem maintenance, and rates of decline are within those determined acceptable for the vegetation present • Modelling shows that mass and of nutrients and discharged to ecosystems are within the acceptable range for indicator species present, and receiving waters remain within the water- quality criteria for the relevant ecosystem (ANZECC- 2000a) • Aquifer unlikely to contain stygofauna (ie aquifer is anaerobic or has no macropores) Residual risk assessment (operational) • Confirmation of achievement of precommissioning residual risk assessment criteria, based on additional field and laboratory measurements and modelling • Modelling and data from trials, including groundwater geochemical monitoring, or ecotoxicological studies reveal no adverse effects on aquifer ecosystems, connected water bodies or groundwater- dependent ecosystems
Table 5.17 (continued) Preventive measures or simplified • Site selection as above and residual risk • Reduce of long- lasting pesticides and antibiotic substances to benign levels for the species present in the ecosystem, and in any biological treatment systems in use • Reduce metals and turbidity to levels, where they impact on ecosystems or surface water systems receiving purge water • Operate the system to avoid inducing increased hazard concentrations via increased discharge of groundwater into the ecosystem • Move site to increase separation from groundwater-dependent ecosystems; ensure attenuation zone excludes groundwater- dependent ecosystems • Adjust recharge and recovery rates (and number or type of wells) so that hydraulic head variations in groundwater-dependent ecosystems meet acceptance criteria above Residual risk assessment (operational) • As for precommissioning residual risk assessment • Further reduce concentrations of water-quality hazards • For ecosystems with high ecological value, establish criteria (eg groundwater level range, maximum rate of change of groundwater level, concentration range of pertinent constituents) for one or more relevant observation wells, and evaluate monitoring results obtained during the trial Validation monitoring • studies or validation monitoring of abundance and biodiversity of species at locations and frequencies relevant to the ecosystems, and of the potential impacts of managed aquifer recharge (including those on stygofauna, if relevant) c f t i
Table 6.2 Clogging types, causes, diagnosis and methods for management Clogging mechanism Minimisation and prevention Renovation technique and Air entrainment, gas binding Filtration of suspended solids Chemical precipitation, ion exchange • falling water • Presence of gas in source water • reactions • in source water or deposited in pipes • Treatment byproducts (eg alum) • Algal growth in basins • Redox reactions • Incompatibility between source water, groundwater and aquifer materials • Presence of reactive clays (swelling/disper sion) • Avoid cascading • Gas trap • Degas source water • Prevent reactions (eg N2 production) • Improve pretreatment of source water, especially removal of suspended solids • Prevent light (algal growth) • Backwash wells or dry out basins more frequently • Improve pretreatment • Adjust source-water pH or cation concentration • Avoid or remove dissolved oxygen in source water • Backwash more frequently • Pumping • Waiting for gas to • Improving well design • Pumping • Surging • Jetting • Basin drying or • Pumping • Wire brushing • Acid treatment • Basin scraping • Analyse water temperature and specific gases • TSS, turbidity, MFI, particle size distribution of source water and soil/aquifer • Bypass filter testing • Changes in specific capacity (wells) • analyses (especially redox conditions and mineral saturation indices) • SEM analysis of backwash water or soil and aquifer samples (scrapes of well face for deep systems) • Photography (basins) and down-hole TV camera survey C u
Table 6.2 (continued) Clogging mechanism Minimisation and prevention Renovation technique Measurements and techniques Microbial growth • substrate in source water N, and AOC) • Improve source- water pretreatment, especially nutrient removal or chlorine dosing • Backwash more frequently • Adapt duration of wetting and drying cycles in basins • Pumping • Chlorine shock dosing • Acid treatment • Heat • Wire brushing • Multienzyme solutions • Basin drying or scraping • analyses • Photography (basins) and down-hole TV camera survey • Chemical and microbial analyses on soil and aquifer samples AOC = assimilable organic carbon; MFI = membrane filtration index; N = nitrogen; = phosphorous; SEM = scanning electron microscope; TSS = total suspended solids; TV = television. Source: adapted from Pyne (1995), Pérez-Paricio and Carrera (1999). Box 6.1 Identification and management of chemical clogging Fresh, oxygenated, low-pH groundwater from a surficial aquifer on South Goulburn Island, Northern Territory, was injected into an underlying brackish sandstone aquifer known to contain pyrite. This resulted in clogging of the injection well by iron oxyhydroxides. This was largely anticipated during the feasibility phase of the project, on the basis of geochemical modelling drawn from source and receiving water-quality data and core sample mineralogical analyses. Clogging was subsequently controlled by installation of a dedicated pump, to enable weekly backwashing of the aquifer storage and recovery well (Pavelic et al 2002a). 6.1.3 Tools for predicting clogging Numerous techniques have been developed to predict clogging. These range in complexity from the measurement of simple water-quality indices through to sophisticated process-based modelling. A summary of the main techniques is given below. Measures of recharge water-quality parameters Measures of recharge water-quality parameters that are useful indicators of the clogging potential of managed aquifer recharge systems include: • physical clogging – turbidity – total suspended solids – membrane filtration index • microbial clogging – total organic carbon – dissolved organic carbon C u
Table A3.1 (continued) Hazard Methods of analysis Information provided References Salinity and sodicity • Literature • Sampling and analysis of source water and native groundwatera • Sampling and analysis of soil and aquifer • Laboratory-scale column and batch tests • Geochemical modelling • Solute transport modelling • Indicative source concentrations • Source concentration, physicochemical characteristics of ambient groundwater • Presence and quantity of reactive clays and salt loads • Assistance with operational design • Degree of mixing in subsurface NRMMC–EPHC–AHMC (2006) Herczeg et al (2004) Bekele et al (2007) Bekele et al (2007), Cavé (2000) Pavelic et al (2006b,c) Nutrients • Literature • Sampling and analysis of source water and native groundwatera • Sampling and analysis of soil and aquifer • Laboratory-scale column and batch tests • Indicative source concentrations • Source concentration, physicochemical characteristics of ambient groundwater • Presence and quantity of reactive phases • Fate and transport, assistance with operational design NRMMC–EPHC–AHMC (2006) Vanderzalm et al (2006) Vanderzalm et al (2006) Fox (2002) Organic chemicals • Literature • Sampling and analysis of source water and native • Sampling and analysis of soil and aquifer • Passive samplers • Laboratory-scale column and batch tests • Geochemical modelling (PHREEQCb, PHT3Dc) • Tracer testing, aquifer pump testing, electromagnetic down-hole flow metering • Indicative source concentrations and environmental fate data • Source concentration, physicochemical characteristics of ambient groundwater • Presence and quantity of reactive phases • Integrated source concentrations at low levels of detection • Fate and transport, assistance with operational design • Quantitative understanding of processes • Groundwater flow velocity, travel times Appendixes 5 and 6, NRMMC– EPHC–AHMC (2006), NRMMC– EPHC–NHMRC (2009) Pavelic et al (2005) Pavelic et al (2005) Komarova et al (2006) Ying et al (2003) Greskowiak et al (2006) Freeze and Cherry (1979), Clark et al (2005), Pavelic (2006b)
Table A5.1 Environmental fate data for organic chemicals Chemical Molar mass (g/mol) Density (kg/m3) pKa Water solubility (mg/L) KH (M/atm) Sorption coefficients Biodegradation half-life (days) at 25°C Log Kow Log Koc Aerobic Anaerobic Chlorinated alkanes Chloromethanes Bromoform 252.7 2889 [1] – 3100 [1] 1.88 [2] 2.37 [2] 2.18 [3] >120 [4] field trial <1 methanogenic conditions 8–12 denitrifying conditions [5] field trial Bromodichloromethane 163.8 1971 [6] – 6735 [3] 0.42–4.72 [1] 1.88 [1] 2.10 [6] 1.68 [3] >120 [4] field trial 9–29 methanogenic conditions 27–35 denitrifying conditions [5] field trial Chloroform 119.4 1498 [6] – 7950 [1] 0.27–0.34 [1] 1.97 [2] 2.22 [6] 1.77 [3] >120 [4] field trial 13–18 methanogenic conditions 53–84 denitrifying conditions [5] field trial Dibromochloromethane 208.3 2440 [1] – 4000 [1] 0.13–1.00 [1] 2.08 [1] 1.92 [1] 1.89 [3] >120 [4] field trial 11–36 methanogenic conditions 22–35 denitrifying conditions [5] field trial Dichloromethane 84.9 1326 [6] – 13200 [6] 0.31–0.44 [6] 1.25– 1.30 [6] 1.00– 1.25 [6] 7–28 [7] unacclimated lab test 28–112 [7] unacclimated lab test
Table A5.1 (continued) Chemical Molar mass (g/mol) Density (kg/m3) pKa Water solubility (mg/L) KH (M/atm) Sorption coefficients Biodegradation half-life (days) at 25°C Log Kow Log Koc Aerobic Anaerobic Primidone 218.3 – – – – – – – persistent [23] SAT Roxithromycin - – – – – – – – degradable [20] estimate Salicylic acid 138.1 – 3.0 [20] 2240 [15] 1.36E+05 [15] 2.26 [15] 1 [20] – degradable [20] estimate – = not available; EDTA = ethylenediaminetetraacetic acid; SAT = soil aquifer treatment. a Transformation product/s exhibit similar or greater toxicity (see Table A5.2 for fate data). References: [1] Montgomery and Welkom (1991) [2] Dillon and Toze (2005) [3] Cabridgesoft Corporation (2004) [4] Pavelic et al (2006a) [5] Pavelic et al (2005) [6] Mackay et al (1992) [7] Howard (1991) [8] Montgomery (1997) [9] Illinois General Assembly (2008) [10] Howard (1989) [11] IPCS (2008) [12] Oliver et al (1996) [13] Vogel (2005) [14] Wauchope et al (1992) [15] SRC (1999) [16] APVMA (2007) [17] Barbash and Resek (1997) [18] DPR (2007) [19] Ying et al (2003) [20] Kahn and Rorije (2002) [21] Greskowiak et al (2006) [22] NICNAS (2001) [23] Amy and Drewes (2007).
Do you have data on the aquifer mineralogy or no elemental composition? yes Does reliable existing data or baseline no monitoring indicate no As>1 µg/L* in ambient groundwater? Is As in recovered water from nearby MAR operations >7 µg/L? No arsenic no expected yes yes yes Is As present with oxidised (ie Fe oxides) or reduced (ie pyrite) minerals? oxidised or aerobic aquifer contain aerobic (oxidised) or anaerobic (reduced) minerals? reduced or anaerobic No reductive dissolution of no Fe(III) oxide expected Will source water lower the no pH of the storage zone? No pyrite no oxidation expected No arsenic release expected yes Dissolution of Fe(III) oxide expected yes Pyrite oxidation expected Pyrite oxidation and no arsenic release may be slow Arsenic release expected† Eh = a measure of redox potential — the propensity for oxidation and reduction reactions; MAR = managed aquifer recharge; OC = organic carbon. * Arsenic (As) concentrations should be reported to 1 µg/L. †Other trace metals (see Table A7.1) can be released concurrently. Figure A7.1 Decision tree for identifying arsenic mobilisation in managed aquifer recharge (from Vanderzalm et al, 2009) Arsenic release (Figure A7.1) may also indicate release of other hazards, such as cobalt, chromium, copper, nickel and zinc. It is recommended that groundwater arsenic concentrations, which are used as a surrogate to indicate arsenic in the sediments, be reported to a 1 µg/L detection limit. A concentration reported to a higher detection limit (ie <5 µg/L) does not preclude the potential for sufficient arsenic release to exceed guideline values. The decision tree for iron (Figure A7.2) can be used to consider the potential for iron release and the subsequent recovery of water elevated in iron, or aquifer clogging due to the precipitation of iron oxides in the vicinity of the recharge point. As manganese exhibits
Do you have data on the aquifer mineralogy or no elemental composition? yes Has Fe been confirmed in the storage zone? yes data or baseline no monitoring indicate Fe>0.1 mg/L in ambient groundwater? yes recovered water no from nearby MAR no operations >0.3 mg/L? yes No Fe release expected no No Fe(III) clogging Is Fe present with oxidised (ie oxides) or reduced (ie sulfide) minerals? oxidised or aerobic Does the contain aerobic (oxidised) or anaerobic (reduced) minerals? reduced or anaerobic yes Fe(III) clogging expected expected Will source water lower the pH of the no storage zone? Does source water contain OC (ie will lower the Eh of the storage zone)? contain O2, NO3 No Fe expected yes yes no yes Dissolution of Fe(III) oxide and Fe(II) release expected and no Fe release may be slow yes No reductive dissolution of Fe(III) oxide expected Increased Fe in recovered water expected oxidation, Fe(III) oxy/ hydroxide precipitate No Fe release expected Fe(III) clogging expected Eh = a measure of redox potential — the propensity for oxidation and reduction reactions; MAR = managed aquifer recharge; OC = organic carbon. Figure A7.2 Decision tree for identifying potential for iron mobilisation or iron P
Table A7.1 Trace ions posing a concern to human health or the environment that can be released during managed aquifer recharge Trace ion Sources Mechanisms Healtha Environmentb Aluminium • Al(III) • pH aesthetic 9 • gibbsite in laterites • mineral equilibrium • clay minerals Antimony • sulfides • redox 9 – Arsenic • sulfides • redox 9 9 • Fe(III) oxides • pH • exchange Barium • barite (barium sulfate) • mineral equilibrium 9 – • Fe(III) oxides • redox (sulfate • carbonates reduction) • pH • exchange Beryllium • beryl (silicate) • mineral equilibrium – 9 Cadmium • sulfides • redox 9 9 • Fe(III) oxides • pH • exchange Chromium • sulfides • redox 9 9 • Fe(III) oxides, • pH • chromite in olivine inclusions in basalts • exchange Cobalt • sulfides • redox – 9 • Fe(III) oxides • pH • exchange Copper • sulfides • redox 9 9 • Fe(III) oxides • pH • exchange Fluoride • fluorite • mineral equilibrium 9 9 • apatite in igneous rocks Iron • Fe(III) • redox aesthetic 9 • sulfides • pH • carbonates • mineral equilibrium Lead • sulfides • redox 9 9 • Fe(III) oxides • pH • exchange Manganese • oxides • redox – 9 • carbonates • pH • mineral dissolution
Appendix 10 Examples of Australian managed aquifer recharge sites Table A10.1 provides an inventory of some managed aquifer recharge case study sites. The list is not exhaustive; further information can be obtained from the references provided below. TableA10.1 Inventory of managed aquifer recharge case study sites Site (year of Type of Aquifer Source of Infrastructure Annual Further commence- MAR type water recharge information ment) volume (ML) Angas Bremer, SA (mid-1970s) ASR Tertiary limestone River flow ∼30 drainage wells 1000 Gerges et al (1996) Scotch ASR Fractured River flow 1 injection well 40 Gerges et al College, SA (1989) Andrews Farm, SA (1993) Northfield, SA (1993) Greenfields, SA (1995) ASR Tertiary limestone (confined) ASR Fractured rock ASR Tertiary limestone 1 well Stormwater Wetland 1 injection well 3 obs wells Stormwater Wetland 1 drainage well 1 obs well Stormwater Wetland 1 drainage well (2002) 100 Dillon et al (1997), Barry et al (2002), Pavelic et al (2006b) 40 Stevens et al (1995) 100 Gerges et al (1996) (confined) 1 obs. well Paddocks, ASR Tertia ry Stormwater Wetland 75 Gerges et al SA (1995) limestone (confined) 1 injection well (1996) Clayton, SA ASR Tertia ry Lake water 1 injection well 70 Gerges et al (1995) limestone (confined) 7 obs wells (1996) Bolivar, SA ASR Tertia ry Treated 1 ASR well 200 Dillon et al (1999) limestone sewage (confined) 16 obs wells (1999), Dillon et al (2003) Parafield, SA (2003) ASR Tertiary Stormwater limestone Storage basins and wetland 400 Marks et al (2005) (confi ned) 2 ASR wells 12 obs wells Parafield ASTR Tertia ry Stormwater 4 injection wells 400 Rinck-Pfeiffer Gardens, SA (2006) limestone