AWWA ACE63230

This paper describes the steps and results that were taken to lower radionuclide levels in a single 1-mgd well that feeds a localized area in Pasco County, Florida. Pasco County, located on the Gulf Coast of Florida north of the Tampa Bay Metropolitan Area, provides water to nearly 250,000 residents through a county-wide conveyance and distribution system. The County's water supply comes from groundwater pumped through 29 dispersed wells throughout the County and three interconnects with a local wholesaler. As part of monitoring for radionuclides, Pasco County discovered levels of gross alpha and combined radium 226/228 that exceeded regulated limits in one of their wells, LB Well No. 2. Once discovered, the County immediately shut-down the well until corrective measures could be identified and implemented. Two corrective measures were considered: re-construction of the existing well to possibly limit or eliminate contributing zones in the aquifer; and, treatment. A hydrogeologist and driller were contracted to perform logging of the well to identify aquifer zones that could potentially be isolated. For treatment, single use ion exchange, conventional ion exchange, pre-formed hydrous manganese oxide filtration and reverse osmosis were considered. Four different equipment vendors specializing in the treatment of radionuclides were contacted and requested to prepare and submit an equipment cost estimate. Eight different estimates were received and evaluated. These were used as the basis for preparing a conceptual level design and cost estimate for capital, operations and maintenance costs for each. Includes 4 references, tables.