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R604-SUMMATION REPT.6-92 . <br /> ( <br /> Carbon Absorption System. <br /> January 4 , 1991 Completion of vapor extraction pilot <br /> • test , 1160 pounds of gasoline range <br /> hydrocarbons removed from the soil . <br /> i <br /> April 26 , 1991 Vapor extraction under 40 day interim <br /> variance. <br /> June 5 , 1991 Vapor extraction under variance; <br /> removed 3088 pounds of gasoline <br /> range hydrocarbons from the soil and <br /> ground water. <br /> August 9 , 1991 Installation of 4 vapor extraction <br /> wells near P3 ( P3A, P3B, P3C and <br /> P3D ) . <br /> March 31 , 1992 Vapor extraction under Authority to <br /> Construct ; 13 , 116 pounds of gasoline <br /> range hydrocarbons removed from the <br /> soil and ground water . <br /> During this time ground water samples were obtained from the 6 on- <br /> site ground water monitoring wells and included with the vapor <br /> recovery update status reports that are on file with the Regional <br /> Water Quality Control Board and San Joaquin County Health. In <br /> summation of ground water monitoring results , see Table 2, the <br /> ground water beneath this site has been remediated using vapor <br /> extraction. MW5 , sampled on November 21 , 1990 exhibited the <br /> highest degree of contamination; 31 parts per million (ppm) <br /> gasoline range hydrocarbons in the ground water with 5 .4 ppm <br /> benzene , 7 . 3 ppm toluene , 0 .11 ppm ethylbenzene and 7 .B ppm <br /> I xylenes . The last sampling round conducted on June 2, 1992, <br /> i showed all wells to be below detection limits of <0.05 ppm <br /> gasoline , <0 . 0003 ppm benzene , <0 . 0003 ppm toluene , <0 .0003 ppm <br /> ethylbenzene and <0 .0009 ppm xylenes . <br /> The vapor extraction carbon absorption system is currently <br /> removing 11 pounds per day of hydrocarbons , predominately from the <br /> capillary fringe, above ground water at MW1 and MW5 , see Table 3B. <br /> We anticipate the completion of the remediation of this site in <br /> approximately one year, thus the need to perform verification <br /> sampling will have to be performed during tnis time. <br /> TIME FRAME <br /> JULY, 1992 Installation of offsite, monitoring <br /> well MW7 on Angelos Parisis property <br /> and destruction of vapor recovery <br /> wells P1 , P3-Swarm and EX along with <br /> 3 on site confirmation soil sample <br /> • borings . <br /> page 3 <br />