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u <br /> OXYGEN TREATMENT AND ANALYSES <br /> Soil and groundwater samples will be prepared for treatment by mixing the required mass of soil and <br /> groundwater and adding the appropriate mass of MTBE gasoline to each sample. The samples will <br /> be homogenized to provide adequate mixing. Soils and groundwater have been sampled from the <br /> area of contamination, but will be spiked with MTBE gasoline to ensure that adequate BTEX, TPH <br /> and MTBE mass is present to observe the desired reactions. <br /> Soil and groundwater samples will be treated with 30 times the predicted stoichiometric dose of <br /> oxygen (samples will be analyzed after a set sparge time which is representative of the appropriate <br /> oxygen dosing). <br /> Oxygen will be generated and sparged using an oxygen tank (99.5% purity) fed at 0.50 liters per <br /> minute. The control sample will be run using breathing air under the sample flow conditions. <br /> Sample Preparation <br /> Control <br /> 200 grams (g ) soil. <br /> 400 milliliters ( ml) groundwater. <br /> 1 , 000 ml Erlenmeyer Flask. <br /> 200 pL of MTBE-gasoline sample (shaken vigorously into water and soil after addition ). <br /> Sample will be allowed to equilibrate for 24 hours. <br /> Oxvaen Sample: <br /> 400 ml groundwater. <br /> 1 , 000 ml Erlenmeyer Flask. <br /> 200 pL of MTBE gasoline sample (shake vigorously into water and soil after addition . <br /> Sample will be allowed to equilibrate for 24 hours. <br /> Sample will be treated with oxygen for 10 minutes 4 times a day for one week at a rate of 10 <br /> standard cubic feet per hour (scf/hr) or approximately 0. 5 liters per minute. <br /> Treatment Procedure <br /> Each 1 , 000 mL Erlenmeyer flask will be plumbed to the oxygen tank with a sealed cap and an inlet <br /> and outlet tube. The inlet will be attached to a glass tube inserted to the bottom of the flask. The <br /> tube will be placed at the bottom of the flask and oxygen will pass through the soil and water up <br /> through the head space of the container and out the outlet tube. The outlet tube will be attached to a <br /> large sealed bag to collect off-gasses. The control will be sparged with breathing air. A gas sample <br /> will be taken at the start of each test, once three headspaces of gas have purged the container. <br /> Initial gas concentrations (before sampling) will be assumed to be at equilibrium and will be <br /> estimated using the Henry's constant for each compound (an average value will be used for TPHg ). <br /> The measured gas sample will be used to estimate the mass of TPH/MtBE volatilized during the test. <br /> The control will be used to assess the difference between air sparging and oxygen sparging. Final <br /> gas samples will be taken at the end of the test to evaluate final gas concentrations prior to <br /> shutdown, using the sample procedure. <br /> Analytical Methods <br /> Post treatment metals concentrations will be measured in filtered groundwater at the end of the <br /> treatment by EPA Method 6010. Chromate will be measured by a HACH field method using an Ultra <br /> Violet Visible detector (UV-vis) or spectrophotometer. Chromate will be measured by EPA Method <br /> 7196A only if the total chromium concentration and field method indicate dissolved <br /> chromium/hexavalent chromium is above 10 pg/L. Groundwater will be analyzed for TPHg, BTEX, <br /> MtBE, TBA, TBF and acetone by EPA Method 8260. <br /> If chromate is detected in a treated sample the sample will be allowed to react further for 1 to 2 <br /> weeks or until the chromate in the water dissipates. Water samples will be submitted once chromate <br /> has dissipated to document the reduction. <br /> 2130 workplan 2-07 <br />