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r <br /> 27 June 1996 <br /> AGE-NC Project No. 95-0118 <br /> ? Page 8 of 23 <br /> For the IAS pilot test, wells MW-1, MW-2,MW-3, VW-1 and VW-2 were utilized for observation <br /> points. Each well was fitted with air-tight well caps, valves and tubing for monitoring pressure and <br /> organic vapor concentrations in each well. Dissolved oxygen concentrations were measured in MW- <br /> 2,MW-3 and VW-l. <br /> =; 6.1.2. COLLECTION OF GROUND WATER SAMPLES <br /> On 01 February 1996, quarterly ground water samples were collected from all the monitoring wells . <br /> on site,as described in Section 4.0. Samples were transported under chain-of-custody to MAI and <br /> =� analyzed for TRH-g and BTE&X in accordance with EPA methods 5030 and 602. Samples were <br /> collected for the first quarter of 1996 to provide baseline concentrations before the IAS test. The <br /> standard quarterly sampling event in May will provide data to detect changes in hydrocarbon <br /> concentrations. <br /> On 12 February 1996, a groundW _ex__samp1,e__was_xQlleclpd•-from MW 6. The sample was <br /> transported der-eh�'oT=c Cody to MAI and analyzed for dissolved iron in accordar'�i#h..E_PA <br /> me 36.1. The samples were collected,to determine concentrations of dissolved iron. Iron in the <br /> ground water can cause clogging of the sparging point and soil pore space through oxidation of the <br /> ironin pore spaces. The presence of high concentration of iron would indicated that air sparging <br /> I <br /> could become hindered over a long duration. <br /> 6.1.3. FIELD MEASUREMENTS AND DATA COLLECTION <br /> Induced pressure, organic vapor concentrations, ground water depth and dissolved oxygen were <br /> measured at MW-2, MW-3 and VW-1 throughout the test. Measurements were also collected at the <br /> vadose well in VW-2 and at MW-1. Induced pressure was measured at the wells using Magnehelic <br /> differential pressure gauges; organic vapor concentrations were measured at each well head using <br /> 'J <br /> a photo-ionization detector (PID); ground water depth was measured using a Solinst water level <br /> meter; and dissolved oxygen was then measured using a YSI Model 55 dissolved oxygen meter. <br /> After collection of measurements,the air-tight well cap was replaced. Data collected during the IAS <br /> pilot test is summarized on Table 6. <br /> 6.2. RESULTS OF IN-SITU AIR SPARGING PILOT TEST <br /> 6.2.1. INDUCED PRESSURE <br /> } At most monitoring points, the measured induced pressure had an initial increase followed by a <br /> i <br /> i <br /> 1 <br />