Arsenic Control During Aquifer Storage Recovery Cycle Tests in the Floridan Aquifer

Abstract

Implementation of aquifer storage recovery (ASR) for water resource management in Florida is impeded by arsenic mobilization. Arsenic, released by pyrite oxidation during the recharge phase, sometimes results in groundwater concentrations that exceed the 10 µg/L criterion defined in the Safe Drinking Water Act. ASR was proposed as a major storage component for the Comprehensive Everglades Restoration Plan (CERP), in which excess surface water is stored during the wet season, and then distributed during the dry season for ecosystem restoration. To evaluate ASR system performance for CERP goals, three cycle tests were conducted, with extensive water-quality monitoring in the Upper Floridan Aquifer (UFA) at the Kissimmee River ASR (KRASR) pilot system. During each cycle test, redox evolution from sub-oxic to sulfate-reducing conditions occurs in the UFA storage zone, as indicated by decreasing Fe(2+) /H2 S mass ratios. Arsenic, released by pyrite oxidation during recharge, is sequestered during storage and recovery by co-precipitation with iron sulfide. Mineral saturation indices indicate that amorphous iron oxide (a sorption surface for arsenic) is stable only during oxic and sub-oxic conditions of the recharge phase, but iron sulfide (which co-precipitates arsenic) is stable during the sulfate-reducing conditions of the storage and recovery phases. Resultant arsenic concentrations in recovered water are below the 10 µg/L regulatory criterion during cycle tests 2 and 3. The arsenic sequestration process is appropriate for other ASR systems that recharge treated surface water into a sulfate-reducing aquifer.

Probabilistic Approach to Evaluation of Metal(loid) Fate During Stormwater Aquifer Storage and Recovery

“…Water quality improvements include the inactivation of pathogens , a reduction in nutrient concentrations , or degradation of organic chemicals , including personal care products . However, subsurface storage can also have deleterious effects on the quality of groundwater that is available for recovery and reuse, through increases in the concentration of major ions and salinity , metals and metalloids , and hydrogen sulfide .…”

Science synthesis for management as a way to advance ecosystem restoration: evaluation of restoration scenarios for the Florida Everglades

“…ASR systems have some disadvantages. Surface waters may react with aquifer geology affecting water quality, resulting in high concentrations of alpha radioactivity and arsenic (Mirecki ). ASR has been field‐tested in south Florida; however, a recent review of the large‐scale viability of this storage technology has not proven feasible at the scale envisioned in Comprehensive Everglades Restoration Plan (CERP; SFWMD, USACE ).…”

Fractures as Preferential Flowpaths for Aquifer Storage and Recovery (ASR) Injections and Withdrawals: Implications for Environmentally Sensitive Near-Shore Waters, Wetlands of the Greater Everglades Basin and the Regional Karst Floridan Aquifer System

“…Previous analysis of ASR by the ACOE, with its consultants (Mirecki, Bennett & Lopez-Balaez, 2013), was scientifically flawed because it failed to consider preferential flow through fractures and did not even acknowledge the presence of fractures associated with that ASR site. This deficiency occurred despite the fact that two documents (ACOE, 2004c; produced by the agency of the senior author in that evaluation (Mirecki et al, 2013) identified multiple data sets of lineaments representing fractures in southern Florida, including the vicinity of the Kissimmee River. The influence of heterogeneous flow in the Floridan aquifer system influences ASR injections and withdrawals (Hutchings, Vacher, & Budd, 2004).…”

“…The influence of heterogeneous flow in the Floridan aquifer system influences ASR injections and withdrawals (Hutchings, Vacher, & Budd, 2004). More specifically, none of the fractures in the vicinity of the ASR well at the single ASR site analyzed by Mirecki et al (2013), in the vicinity of the Kissimmee River, were identified or monitored in the study, no extensive monitoring network was established in the Kissimmee River. In fact, neither this nor any of the other ASR tests evaluated in our study included isotopic analysis, trilinear chemical analysis or tracer analysis, such as those described by Bacchus et al (2014), Davies et al (2004), Fetter (1988), Freeze and Cherry (1979), Kincaid et al (2004), Kincaid, Davies, Werner, and DeHan (2012), Schindel et al (2004) and Wilcox, Solo-Gabriele and Sternberg (2004), of the ambient ground water, injected water or "recovered" water at the ASR sites.…”