This five-year study is divided into two phases, the first of which was two years long. The first phase laid the groundwork for data inventory, review, and analysis, and the second phase will allow for collection of additional data as it becomes available, expand the hydrogeologic framework, and perform a more complete comparative analysis of ASR sites. The study is in the second phase.
Precedence for ASR in southern Florida has been set with wells having been constructed at over 30 sites, mostly by local municipalities or counties in coastal areas. The Upper Floridan aquifer, the aquifer used at most of these sites, is brackish to saline in south Florida, which can have a large impact on the recovery of the fresh or potable water recharged and stored. Few regional investigations of the Floridan aquifer system hydrogeology in south Florida have been conducted, and the focus of those studies was not on ASR. Lacking a regional ASR framework to aid the decision-making process, ASR well sites in south Florida have been primarily located based on factors such as land availability, source-water quality, and source-water proximity (preexisting surface-water bodies, surficial aquifer system well fields, or water treatment plants). Little effort has been made to link information collected from each site as part of a regional hydrogeologic analysis.
Results of this study should help the managers of the CERP program in locating, designing, constructing, and cycle testing ASR wells. These results should help establish a standard cycle testing protocol that can be used to measure the performance of individual CERP wells or clusters of wells.
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Memberg, S. J.
Cunningham, K. J.
An inventory of data available at all ASR sites, including site identification, location, construction data, geophysical log data, aquifer test data, core data, and water-quality data, is nearly complete.
Several GIS map illustrations have been completed. One shows where ASR wells and facilities have been constructed or are planned in South Florida. Others show key parameters for the purpose of comparison of ASR facilities, such as the thickness and diameter of the constructed open borehole.
Collection and compilation of cycle testing data from published reports, consulting reports, and monthly operationing reports was begun. Recovery efficiencies for most of the sites have been determined; however, at many of the sites only 2 or 3 cycles have been conducted and the recovery efficiency determined thus far could be unreliable.
Hydrogeologic tops in the Floridan aquifer system from three reports by Reese and others on the aquifer system were collated into one table for the purpose of constructing maps covering most of southern Florida.
Some ASR sites having performance problems or potential for problems have been identified. Knowledge of the factors contributing to these problems can assist municipalites and regulators in determining optimal site selection or contruction methods or both for future ASR sites.
Data collection and inventory which involves visiting ASR facilities and water treatment plants, obtaining monthly operating reports and daily operational data, and obtaining well completion and cycle testing reports from consulting firms. The data will be inventoried using spreadsheets.
The hydrologic framework data developed in previous studies will be reivsed and expanded using ASR well and other recently drilled wells. Hydrogeologic tops will be determined and maps showing the tops of the Upper Floridian aquifer, thickness of important units, and the distribution of transmissivity of the aquifer or zones within the aquifer (storage zones) will be developed.
Available cycle testing data (rates, volumes, storage periods, and salinity of recovered water) will be evaluated. Recovery efficiencies (on a per cycle basis and on a cumulative basis) will be determined by two different methods and plots constructed. Comparative analyses of all ASR sites with adequate data will be conducted. Recovery efficiencies will be related to hydrogeologic and design/management factors including any operational problems that are occurring at a site.
Reports and illustrations will be prepared.
1. Data Collection and Inventory Continue to visit ASR facilities and water treatment plants, obtain monthly operating reports and daily operational data, and obtain well completion and cycle testing reports from consulting firms. Inventory data using spreadsheets. Input well location and construction data into the GWSI module of NWIS.
2. Hydrogeologic delineation Geologic and hydrogeologic tops, flow zones, ambient salinity, and hydraulic properties will be determined at each site using geophysical logs, lithology, pump test, and other data. These interpretations and results will be related to the regional hydrogeologic framework of the Upper Floridan aquifer developed in previous or concurrent studies, including the regional structural and stratigraphic setting and distribution of salinity and permeability. During phase 1 of this project cycle test data from several sites suggested that salinity, transmissivity, and geologic structure can affect the efficient recovery of recharged feshwater, and salinity and transmissivity in the Upper Floridan aquifer are related to structure and stratigraphy.
3. Evaluation Determine recovery efficiencies by two different methods (on a per cycle basis and on a cumulative basis) and construct plots showing volumes recharged and recovered with time and the variation of salinity during recovery for each cycle. Relate recovery efficiencies to hydrogeologic, design, and management factors from 1 and 2 above, including any operational problems that are occurring at a site. Conduct a comparative analysis of all ASR sites having adequate data using the factors determined to be most important. Determine the trend of recovery efficiency with cumulative water recharged at each site, and relate these trends for all sites.
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U.S. Department of the Interior, U.S. Geological Survey, Center for
Coastal Geology
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