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f REG 603 UPDATE-9 9/14/92 I sample results , the samples obtained on 11/27/90 and later were analyzed using EPA methods 5030 and 602 for Total Fuel Hydrocarbons and BTEX. The next quarterly sampling to occur in September , 1992 . s � 3 .0 RESULTS I� { 3 . 1 PRODUCT AND RECOVERY E During the initial site assessment and during subsequent site visits , floating product was observed in monitor wells MW-1 , MW-3 { � and MW10 . Product thickness in MW-1 has ranged from 0 .01' to 1 .261 and from 0 . 17' to 1 . 66' in MW-3 . Only a product sheen has ' been observed in MW10 ; during the March, June and September, 1991 and the March 10, 1992 samplings . Observations made during this i' update status report show MW1 and MW10 to have a sheen of floating product while MW3 has decreased to 0 .08 feet of floating product. ;I These reductions in product thickness can be attributed to the on going vapor extraction at this site. The recovered g g P gasoline is amber yellow and appears to be fresh (no apparent degradation) . f Involved regulatory agencies suggested that product recovery �I � E commence before an aquifer pump test be performed. i Temporary submersible pneumatic pumps were installed into monitor wells MW-1 and MW-3 for product recovery on October 10 , 1989 . 11, Ij Approximately 40 gallons of gasoline were recovered. The product ' recovery system was removed in February, 1990, and the "ConVault" IN tank, until September , 1990 , was being used for the storage of the r� , purged well water . On May 25 , 1990 a water sample obtained from the "ConVault" indicated that the stored water was free of petroleum hydrocarbons (Table 1 Convault) . This water was later dumped to the sewer after permission was obtained by the Stockton Department of Municipal Utilities (approximately 250 gallons ) . During the November 27 , 1990 monitoring round, 0 . 081 of a clear yellow floating product was again discovered in monitor well MW1 . C This well was purged until depletion of the product was noted; t approximately 1 quart of gasoline was recovered and placed into : the 55 gallon drum storing the water "purged" prior to sampling the wells . Product thickness measurements obtained on subsequent f site visits have shown only a sheen of product in MW1 until September, 1991 when 0 .02 feet of yellow-amber product was discovered. Also wells MW3 has had up to 0 . 28 feet of yellow- amber product and MW10 has a product sheen. The product resurgence corresponds to the commencement of the vapor extraction t source test on MW10 and the start-up of vapor extraction on MW1 , MW2, MW3 , MW10 and the tanks excavation area . 'i j � � PAGE 4