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8. Treatment Objective <br /> The treatment goal for the pilot study will be to treat the arsenic <br /> contaminated groundwater to U.S. Environmental Protection Agency (EPA) maximum <br /> contaminant level (MCL) of 50 ppb for arsenic. Each treatment technology <br /> (i .e. GAC, IE, and AA) will be evaluated with regard to its arsenic removal <br /> capacity at a breakthrough arsenic concentration of 50 ppb (MCL) . <br /> 9. Test Conditions <br /> The hydraulic loading rates that are to be used in the pilot tests are 2.0, <br /> 3.0, and 7.0 gpm/ft , which correspond to flow rates of 0.2, 0.3, and 0.7 <br /> gpm, respectively. These values are within the range of hydraulic loading <br /> rates that are recommended in the literature for operation of GAC/IE/AA <br /> systems in treating arsenic-contaminated water. Each test run will be <br /> conduced dt a fixed bed depth of 4 ft. For hydraulic loadings of 7, 3, and 2 <br /> gpm/ft , this bed depth would result in empty bed contact times (EBCT) of 5, <br /> 10, and 15 minutes, respectively. Based upon the literature reported <br /> information on capacity of IE and AA for arsenic removal and based on vendor <br /> reported GAC adsorption capacity of 2.5 lb As(v)/100 lb carbon, the following ' <br /> run lengths, till the effluent arsenic concentration reaches the 50 ppb MCL, <br /> are estimated at an EBCT of 5 minutes: <br /> 45 days for GAC treatment system. <br /> 45 days for AA treatment system. <br /> 1-10 days for IE treatment system. <br /> These run lengths (elapsed time to breakthrough) are estimated based on <br /> limited information available at this time on arsenic removal capacities of <br /> GAC/IE/AA. The actual length of each run during the pilot study will depend <br /> upon various factors including but not limited to actual characteristics of <br /> the contaminated groundwater, EBCT, and GAC/IE/AA types used in the test run. <br /> Based on the above preliminary estimates on run lengths and based on a flow <br /> rate of 0.7 gpm (EBCT = 5 mins) through each treatment system, it is estimated <br /> that approximately 440,000 gallons of water would have been treated at the <br /> completion of eight test runs. <br /> 10. Analytical Procedures for Arsenic <br /> Water samples will be analyzed for total arsenic at Weston's Analytics <br /> Division by USATHAMA-certified Method SDO1. Weston's current certified <br /> detection level for As (total ) is 5 ppb. <br /> 11. Sampling Procedures <br /> Samples will be taken for arsenic analysis at the influent and effluent of the <br /> first (primary) column, and at the outlet of the second column, in each train, <br /> during each test run. Samples of influent groundwater to be fed to the air <br /> stripper will be analyzed for VOCs in addition to arsenic. Air stripper <br /> effluent (water) will also be analyzed for VOCs. Water will not be discharged <br /> if VOC levels are above detection limits. <br /> 3 <br />