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13, 1990 and the test was shut down until the leak was fixed. The <br /> test resumed on December 27, 1990 and effluent bag sampling along <br /> with the PID screen commenced. Bag samples were obtained from the <br /> effluent of the pump, along with vacuum or pressure readings from <br /> the wells and pump. PID screening of the charcoal exhaust showed <br /> breakthrough occurrin4 on January 4, 1991. At this time an <br /> effluent sample was obtained from the charcoal tub scrub exhaust <br /> prior to shutting the system off and disconnecting it from the <br /> wells. This sample was analyzed using the DHS head pace method <br /> for Total Fuel Hydrocarbons and BTEX. A sample of the influent to <br /> the charcoal was also obtained and chain of custody delivered to <br /> Chemtech Laboratories for analysis using EPA modified 8015 and 602 <br /> for TPH and BTEX respectively. This sample was used for the <br /> profile for shipment of the charcoal to be regenerated. t <br /> Throughout the test vacuum readings were obtained from the ground <br /> water monitoring wells, to help establish the radius of influence <br /> of the vapor extraction system. <br /> PILOT TEST RESULTS <br /> Vacuum readings derived from the extraction wells (EX, P1 and P3) <br /> show a tight formation (high vacuum) . Also vacuum readings <br /> obtained from the ground water monitor wells show vacuum influence <br /> �., covering most of the site with the exception of MW-6, see Figure <br /> 9A. <br /> g � ' �, •, ��,; � `�" -� '�&,b°� '��- .�� � �f`� k1"�C�t+ter�+'t� `n$�. tt,8 <br /> �por stream <br /> „ x A •_ <br /> contains o.92 pounds per day of Benzene, 2.04 pounds per day of s <br /> Toluene, 0.74 pounds per day of Ethyl Benzene and 11.3 pounds per <br /> day of Xylenes, indicating an aged petroleum product <br /> contamination problem. <br /> VAPOR EXTRACTION CONTROL <br /> Tve sitsa, prior to removal of the underground storage tanks and <br /> gasoline dispensing system, operated as a Regal Service Station. <br /> The station was allotted a poundage rate that could be released <br /> i from the dispenser nozzels and tank vents from its retail <br /> = operations. With this in mind, that prior allotment should be <br /> f <br /> allowed for the remediation of this site. <br /> y Western Ciao-Engineers has engineered, installed and are monitoring <br /> k various ongoing vapor extraction systems throughout Northern <br /> California. A system that is economical and relatively <br /> maintenance free is emission rate control by the infrared t1R) <br /> Total Petroleum Hydrocarbon analyzer with valve controls that <br /> page 9 <br />