Risk assessment

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Evaluation of the risk of contaminant breakthrough during MAR application. Especially during the delvelopment of a MAR project, health, environmental and management risks need to be identified and quantified.

Figure 1. Attenuation zone in an aquifer. This plot of hazard concentration on a transect through the aquifer from recharge zone to recovery well shows that an observation well on the perimeter of the predetermined attenuation zone would verify that the required attenuation is achieved within the zone (Page et al., 2010).

Hazards to human health or the environment encountered in MAR facilities may originate from (NRMMC, 2009):

  • recharge water
  • native groundwater
  • aquifer minerals reacting with injected water
  • byproducts of treatment processes or maintenance practices.

Australian guidelines risk assessment approach evaluates the following twelve hazards that need to be evaluated before the implementation of a new MAR facility (NRMMC,2009). Be aware, that dependent on the location of the proposed MAR scheme, also other harzards may arise.

Table 1. Key hazards that can occurr during MAR projects in source water (S), groundwater (G) and aquifer materials (A) (adapted from NRMMC,2009).

Hazard Origin Examples Preventive Measures
Pathogens S, (G) viruses, bacterials adequate aquifer residence time
Inorganic chemicals G, A, S arsenic, manganese, iron control redox potential during recharge (avoid mobilisation)
Salinity or sodicity G, (S) salinity increase volume of freshwater recharge
Nutrients S, (G) nitrogen pretreat water
Organic chemicals S, (G) pesticides exclude prone sub-catchments
Turbidity and particulates S, (G) suspended solids pretreat water
Radionuclides G, A, (S) alpha radiation aquifer selection
Pressures, flow rates, volumes and levels S waterlogging reduce injection pressure
Contaminant migration in fractured rock and karstic aquifers S, (G) polycyclic aromatic hydrocarbons (PAH) pretreat or extent attenuation zone (exclusion)
Aqifer dissolution and well and aquitard stability S, A excess and recovery control pH of source water (avoid dissolution)
Aquifer and groundwater dependent ecosystems S, A levels outside historical range avoid proximity to groundwater-dependent ecosystems
Energy and greenhouse gases S excessive energy use substitute passive treatments for active

Risk assessment tools were used to evaluate possible organic contaminant hazards during ASR (Dillon et al., 2016, 2006; Miller and Correll, 2002; Page et al., 2015, 2007; Vanderzalm et al., 2007). The software ASRRI (ASR Risk Index) is a screening tool to predict the potential for contaminant attenuation during ASR and ASTR (Miller and Correll, 2002). The fate and transport of pathogens during infiltration of treated wastewater in a karstic aquifer was studied by Masciopinto et al., 2008. Greskowiak et al., 2006, 2005 applied MODFLOW and PHT3D to quantify the biogeochemical reactions while infiltrating treated wastewater into an ASR well and showed that the bacterial mass had a significant influence on the local geochemistry in the vicinity of the well. With the help of a probabilistic modelling approach the removal efficiencies of phosphorus, nitrogen and organic carbon during successive ASR cycles were estimated (Vanderzalm et al., 2013).

The INOWAS platform can help to quantify the risks associated with the implementation and operation of a MAR facility by the use of the following tools:

  • T03. MODFLOW model setup and editor
  • T07. MODFLOW model scenario manager
  • T08. One-Dimensional Transport Equation
  • T13. Travel Time Through Unconfined Aquifer
  • T15. Quantitative microbial risk assessment
  • T19. Groundwater residence time

REFERENCES

    • Dillon, P.J., Toze, S., Pavelic, P., Vanderzalm, J.L., Barry, K., Ying, G.-G., Kookana, R., Skjemstad, J., Nicholson, B., Miller, R., Correll, R., Prommer, H., Greskowiak, J., Stuyfzand, P.J., 2006. Water quality improvements during aquifer storage and recovery at ten sites, in: UNESCO (Ed.), Recharge Systems for Protecting and Enhancing Groundwater Resources – Proceedings of the 5th International Symposium on Management of Aquifer Recharge ISMAR5, Berlin, Germany, 11–16 June 2005. pp. 85–94.
    • Dillon, P.J., Vanderzalm, J., Page, D., Barry, K., Gonzalez, D., Muthukaruppan, M., Hudson, M., 2016. Analysis of ASR clogging investigations at three Australian ASR sites in a Bayesian context, in: Proceedings of the 9th International Symposium on Management of Aquifer Recharge ISMAR9, Mexico, Mexico, 20–24 June 2005.
    • Greskowiak, J., Prommer, H., Massmann, G., Nützmann, G., 2006. Modeling Seasonal Redox Dynamics and the Corresponding Fate of the Pharmaceutical Residue Phenazone During Artificial Recharge of Groundwater. Environmental Science & Technology 40, 6615–6621. doi:10.1021/es052506t
    • Greskowiak, J., Prommer, H., Vanderzalm, J., Pavelic, P., Dillon, P., 2005. Modeling of carbon cycling and biogeochemical changes during injection and recovery of reclaimed water at Bolivar, South Australia: MODELING CARBON CYCLING. Water Resources Research 41, W10418. doi:10.1029/2005WR004095
    • Masciopinto, C., La Mantia, R., Chrysikopoulos, C.V., 2008. Fate and transport of pathogens in a fractured aquifer in the Salento area, Italy. Water Resources Research 44, W01404. doi:10.1029/2006WR005643
    • Miller, R., Correll, R., 2002. ASRRI: a predictive index of contaminant attenuation during aquifer storage and recovery, in: Dillon, P. (Ed.), Management of Aquifer Recharge for Sustainability: Proceedings of the 4th International Symposium on Artificial Recharge of Groundwater. ISAR-4, Adelaide, South Australia, 22-26 September 2002. A.A. Balkema, Lisse, pp. 69–74.
    • Natural Resource Management Ministerial (NRMMC), Environment Protection and Heritage Council, and Australian Council, Health Ministers’ Conference, 2009. Australian guidelines for water recycling: Managed aquifer recharge (Phase 2). Canberra, Australia.
    • Page, D., Barry, K., Chassagne, A., Pavelic, P., Dillon, P., Purdie, M., Pittman, C., Rinck-Pfeiffer, S., Regel, R., 2007. Application of the Hazard Analysis and Critical Control Point (HACCP) risk management framework to managed aquifer recharge, in: Fox, P. (Ed.), Management of Aquifer Recharge for Sustainability: Proceedings of the 6th International Symposium on Managed Artificial Recharge of Groundwater, ISMAR6, Phoenix, Arizona USA October 28 – November 2, 2007. Acacia Publishing Incorporated, pp. 578–589.
    • Page, D., Dillon, P., Vanderzalm, J., Toze, S., Sidhu, J., Barry, K., Levett, K., Kremer, S., Regel, R., 2010. Risk Assessment of Aquifer Storage Transfer and Recovery with Urban Stormwater for Producing Water of a Potable Quality. Journal of Environment Quality 39, 2029. doi:10.2134/jeq2010.0078
    • Page, D., Gonzalez, D., Torkzaban, S., Toze, S., Sidhu, J., Miotliński, K., Barry, K., Dillon, P., 2015. Microbiological risks of recycling urban stormwater via aquifers for various uses in Adelaide, Australia. Environmental Earth Sciences 73, 7733–7737. doi:10.1007/s12665-014-3466-4
    • Vanderzalm, J.L., Dillon, P., Marvanek, S., Page, D., 2007. Over 100 years of drinking stormwater treated through MAR: Assessing the risks of stormwater recharge on the quality of Blue Lake, in: Fox, P. (Ed.), Management of Aquifer Recharge for Sustainability: Proceedings of the 6th International Symposium on Managed Artificial Recharge of Groundwater, ISMAR6, Phoenix, Arizona USA October 28 – November 2, 2007. Acacia Publishing Incorporated, pp. 616–625.
    • Vanderzalm, J.L., Page, D.W., Barry, K.E., Dillon, P.J., 2013. Application of a probabilistic modelling approach for evaluation of nitrogen, phosphorus and organic carbon removal efficiency during four successive cycles of aquifer storage and recovery (ASR) in an anoxic carbonate aquifer. Water Research 47, 2177–2189. doi:10.1016/j.watres.2013.01.038