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i R604 :UPDATE 10-JUNE, 1992 Once the 60 cc syringe is removed the plunger is pushed into the syringe to create pressure within the syringe and released to • allow the vapors that have been captured to reach equilibrium. A small dedicated needle attached to a dedicated 1 cc syringe is then inserted into the 60 cc syringe via the soft tubing. Again the lcc syringe is purged numerous times prior to filling it with the sample. All but 0 .5 cc of the sample is ejected into the air prior to infecting the remaining 0 . 5 cc syringe sample into the GC-PID (the calibrant infection is 0 . 5 cc ) . Once the chromatogram has been recorded an instrument blank is run prior to the next sample. The instrument blank will indicate if residual peaks are being carried onto the next analysis . , i While the GC-PID analysis is running for a particular sample ( 15 minutes per sample run) , vacuum influence readings are obtained from the wells by attaching a manometer calibrated in mm water to j sample ports at the well heads . These readings show the mm water pressure or vacuum that is being P g created at each well . VACUUM INFLUENCE Soil contamination has been documented as being associated with the pump dispensers and the tank field; as degraded gasoline range hydrocarbons . Figure 3B shows the outline of the soil contaminated after over excavation. As was stated earlier , vapor recovery has removed the petroleum hydrocarbons from the soil and has greatly reduced the petroleum hydrocarbons dissolved in the ground water beneath this site. Figure 5 shows the vacuum influence exerted from vacuum at EX on May 14 , 1992. Figures 5A and 5B show the decline of the ground water plume from December, 1991 to March, 1992 . These figures represent the field data that ` shows vacuum extraction is successfully removing the hydrocarbon contamination that existed at this site. OPERATION UNDER AUTHORITY TO CONSTRUCT PERMIT # AP 91-106 . The Authority to Construct (Permit No . AP 91-1.06 ) was issued on February 24 , 1992 . Once the carbon scrub units were received (after rejuvenation at Cameron - Yakima) , the vapor recovery system was remanifolded with 2 110 gallon carbon vapor scrub units (R1283 and R1284 ) placed in series behind one Rotron DR505 Blower . Vapor extraction wells P1 , P3 Swarm (P3-A, P3-D, and P3 ) , EX, along with ground water monitoring well MW5, were attached to the manifold and the system was restarted at 12 : 35 PM on March 31 , 1992 . The San Joaquin County Air Pollution Control Officer , Teresa Stuyt, was on hand to inspect the system. i Under the Authority to Construct, the vapor extraction system must be monitored twice weekly , with three measurements of the effluent be performed for the first month , then monthly thereafter. Table 3B represents these measurements , see Appendix B for field notes i and chromatograms , and Appendix C-Permit to Construct . page 7 i