Assessment of the Feasibility of Shallow Well Demineralization Concentrate Disposal in Coastal Areas of the St. Johns River Water Management District: Literature Review

摘要

St. Johns River Water Management District (the District) is exploring options for membrane demineralization concentrate management to promote the development of environmentally responsible alternative water supply. This report compiles hydrogeologic and water quality data from the surficial aquifer system (SAS) of Flagler, Brevard, and Indian River counties to assess the feasibility of shallow Class V well concentrate disposal. Class V, Group 4 wells inject water into or above an Underground Source of Drinking Water (USDW), and the injected water quality must be better than or comparable to that of the receiving aquifer. Data from the District's water quality monitoring network, published U.S. Geological Survey (USGS) and Florida Geological Survey (FGS) reports, District consumptive use permits, and consultant reports reveal a predominantly fresh to brackish water (for the purposes of this assessment, brackish groundwater is classified as having salinities between 1,000 mg/L and 10,000 mg/L TDS) SAS in the study areas. The exception may be along the ocean-side of the barrier islands, particularly in Flagler and southern Indian River counties, where seawater has intruded laterally. These areas offer the greatest potential for Class V well application. For comparison, the hydrogeology and construction of existing Class V disposal well systems at Highland Beach, Florida, and in the Florida Keys are examined in this report. These case studies and a brief discussion of the regulation of Class V injection wells provide guidelines for shallow disposal well siting, testing, and construction in suitable areas of the District. An exploratory drilling program could better delineate the brackish-saline water interface both laterally and vertically along the barrier islands to identify possible locations for pilot Class V injection well systems.