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R604 :UPDATE 11-JULY, 1992 <br />= Ij <br /> VACUUM INFLUENCE <br /> a , <br /> Soil contamination has been documented as being associated with <br /> =I ''d the pump dispensers and the tank field, as degraded gasoline range <br /> hydrocarbons . Figure 5 shows the outline of the remaining <br /> contaminated soil after over excavation and vapor extraction as <br /> of July 20 , 1992. As was stated earlier , vapor recovery has <br /> removed the light ranges of petroleum hydrocarbons from the soil <br /> and has removed the petroleum hydrocarbons dissolved in the ground <br /> �L water beneath this site . <br /> OPERATION UNDER AUTHORITY TO CONSTRUCT PERMIT # AP 91-106 . <br /> The Authority to Construct (Permit No. AP 91-106 ) was issued on <br /> February 24 , 1992 . Once the carbon scrub units were received <br /> (after rejuvenation at Cameron - Yakima) , the vapor recovery <br /> h +I system was remanifolded with 2 110 gallon carbon vapor scrub units <br /> (R1283 and R1284 ) placed in series behind one Rotron DR505 Blower. <br /> Vapor extraction wells P1 , P3 Swarm (P3-A, P3-D, and P3 ) , EX, <br /> ' along with ground water monitoring well MWS, were attached to the <br /> manifold and the system was restarted at 12 : 35 PM on March 31 , <br /> 1992 . The San Joaquin County Air Pollution Control Officer, <br /> f � Teresa Stuyt, was on hand to inspect the system. <br /> ! Under the Authority to Construct, the vapor extraction system must <br /> be monitored twice weekly, with three measurements of the effluent <br /> to be performed for the first month, then monthly thereafter. <br /> Table 3B represents these measurements , see Appendix B for field <br /> notes and chromatograms , and Appendix C-Permit to Construct . <br /> System Operation <br /> i= "t 10nliMarch 31 , 1992 , the influent to the carbons was 4 . 02 pounds per <br /> ! ( lbs/day ) at a flow rate of 57 cubic feet per minute (cfm) . <br /> � day <br /> The effluent measurement from the last carbon was 0 . 32' lbs/day . <br /> = jThis equates to a 92% absorption/destruction of the vapor stream <br /> hydrocarbons . <br /> 3 The 57 cfm flow rate was not maintained; the blower's heat sensor <br /> shut the blower off for a 20 minute cool down. Once the blower <br /> came back on the pump bypass was used to decrease the flow rate to <br /> 28 . 7 cfm, which decreases the pounds per day to 2 .02 on the <br /> j! influent and 0 . 05 on the effluent, ie, 97% absoption/destruction <br /> of the vapor stream hydrocarbons . <br /> i <br /> On subsequent visits the flow rate ranged between 26 cfm to 32 cfm <br /> with the influent dropping from a high of 3.12 lbs/day on April 7 , <br /> 1992 to 1 . 45 lbs/day on April 14 , 1992 . The effluent from the <br /> last carbon ranged from below detection limits to a high of 1 . 07 <br /> lbs/day.. <br /> i Upon adding the additional vapor extraction wells on July 22 , <br /> i ! 1992 , recoverable gasoline range hydrocarbons were increased from <br /> 2 . 4 pounds on July 16 to 10 . 5 pounds on July 22 , 1992 . Presently , <br /> - page 6 <br />