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| STATEMENT OF PROBLEM Hazardous substances, including approximately 50,000 tons of wastes derived from pesticide production, were disposed of in twenty buried waste disposal sites consisting of unlined trenches and pits. SPECIFICS OF PROJECT Dye tracing and mapping of the geology were used to delineate groundwater basins. Work began in December 1995 and was completed in May 1997. SITE DESCRIPTION AND SCOPE OF WORK The 16,000-acre site includes two large chemical factories, primarily involved in the manufacture of pesticides, and a phosphate Furnace plant. Crawford and Associates, Inc. performed a karst hydrogeologic inventory and mapped the potentiometric surface of the uppermost aquifer. Dye receptors were placed in over 50 piezometers/monitor wells and over 130 springs and surface streams. A matrix interference investigation was performed to assess the potential impact of the contaminants on the dyes and dye receptors. A background analysis was performed previous to dye selection and dye injection. The site was divided into 5 dye tracer areas, and a total of 6 dyes were injected into dye injection wells located upgradient from waste burial sites at 16 locations. CONCLUSIONS AND RECOMMENDATIONS The karst investigation and dye tracer study revealed rapid turbulent-flow through karst-conduits to springs, even though the area did not appear to have karst surface features, and previous consultants had not recognized that the area had karst groundwater flow. The final report prepared by Crawford and Associates, Inc. included a map showing the potentiometric surface of the uppermost aquifer, the dye flow routes from dye injection wells installed upgradient from the waste burial sites to springs, and a conceptual model of the hydrogeology. This was probably the largest dye trace ever performed in terms of the number of dye receptor locations. |
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