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Additional (accessory) equipment. In addition to the treatment units <br /> described above, the following additional tankage will be added to the <br /> treatment system: <br /> One or two 3,000-gallon influent holding tanks to receive and hold <br /> groundwater from wells 403 and 431. <br /> One 2,000-gallon equalization tank between the air stripper and the <br /> GAC/IE/AA unit. pH adjustment will be carried out in this tank. <br /> One or two 3,000-gallon effluent holding tanks to retain treated effluent <br /> prior to discharge. <br /> Chlorine oxidation of the groundwater before feeding the treatment system ma <br /> be necessary to oxidize As(III) to AS(V) , because it is reported in the <br /> literature that for all the three treatment technologies (GAC/IE/AA), As(V) <br /> removals are greater than As(III) removals under the same test conditions. <br /> Chlorine oxidation requirement for the pilot study will be evaluated based o <br /> the speciation of arsenic (+3 and +5) in the groundwater from wells 403 and <br /> 431 at SHAD. If chlorine oxidation of the influent is deemed necessary, the <br /> effluent will be tested for residual chlorine by an approved colorimetric <br /> procedure (e.g. , DPD Method) prior to discharge. <br /> 7. Test Program <br /> Air stripper. The primary function of the air stripper in this project will <br /> be to remove volatile organic compounds (VOCs) , TCE in particular, from the <br /> groundwater prior to its entering the GAC/IE/AA pilot plant and to minimize <br /> any effects of these VOCs on the evaluation of GAC/IE/AA effectiveness to <br /> remove arsenic. <br /> Batch (isotherm) Testing of GAC/IE/AA (offsite) . It is estimated that a <br /> total of six isotherm tests with five granular activated carbon types, two <br /> isotherm tests with one activated alumina type and four isotherm tests with <br /> four ion exchange resin types will be conducted at Weston's Laboratory in West <br /> Chester, Pennsylvania. The tests of GAC and activated alumina will include <br /> tests to determine the effects of pH. Based upon the results of the isother <br /> tests , the best performing GNC/IE/AA types will be selected for continuous <br /> flow pilot testing at SHAD. <br /> Continuous flow pilot testADing. A total of eight continuous flow pilot test <br /> runs will ba conducted at SHusing the two GACs, two IE resins , and the <br /> single AA that are identified based upon isotherm test results. Each test run <br /> will be carried out in two parallel trains with each train consisting of two <br /> columns in series. These dual treatment lines will allow for study under <br /> different experimental conditions at the same time. The second column in each <br /> treatment line will maintain effluent (discharge) quality within acceptable <br /> limits while allowing arsenic leakage from the first column up to influent <br /> levels (total exhaustion of capacity of the first column) . <br /> 2 <br />