Laserfiche WebLink
Metadata
Document management portal powered by Laserfiche WebLink 9 © 1998-2015 Laserfiche. All rights reserved.
R604 UPDATE 17 A-27-1993 <br /> BTEX in Ground Water (EPA method 602) : <br /> No wells contained any BTEXs in the samples of the monitoring <br /> wells from the March 5, and June 2, 1992 sampling. During the <br /> December 16 , 1991 sampling round only MW1, MW2, and MW5, had <br /> BTEXs in very low concentrations . During the September 11, 1992 <br /> sampling, sample results from MW1 detected only benzene (1 .2 <br /> ug/L) and MW5 sample results indicated only the xylenes (4 . 1 <br /> ug/L) . The December 7, 1992 sample results showed only MW5 to <br /> contain ethylbenzene (1 . 2 ug/L) and xylenes (35 ug/L) . This most <br /> recent sampling (March 30 , 1993 ) only MW5 contains benzene at 0 4 <br /> ug/L, ethylbenzene at 4 3 ug/L and xylenes at 56 ug/L MW5 is <br /> presently being utilized as a vapor extraction well . This <br /> pulling of the contaminants to the well consequently increased <br /> concentrations <br /> MAXIMUM CONTAMINANT LEVELS FOR PRIMARY DRINKING WATER, TITLE 22 <br /> or DHS. <br /> BENZENE 1 ug/L TOLUENE 100 ug/L <br /> ETHYLBENZENE 680 ug/L Total XYLENES 1, 750 ug/L <br /> Vapor extraction has removed most BTEXs from the ground water as <br /> shown by sample results obtained from the monitoring wells since <br /> March 5, 1992 Except for MWl, which contained 1 2 ppb benzene <br /> on the September 11, 1992 sampling, the "Present California Water <br /> Quality Goals" have been met, see Table 1 <br /> Fecal Coliform: <br /> From December, 1991 through February, 1992 , monthly fecal <br /> coliform samples were collected from monitor wells MW3, MW4, MW5 <br /> and MW6 . Samples were again collected in June, 1992 , from <br /> monitoring wells MW3 , MW4 and MW6 . During the September 11, 1992 <br /> sampling, MW3 and MW6 were dry, no fecal coliform samples were <br /> obtained. Table 2 shows the results of these samples . As of <br /> June, 1992 all these wells are below detection limits, <2 2 MPN, <br /> for fecal coliform. <br /> VAPOR EXTRACTION <br /> Vapor Recovery Results: <br /> The vapor extraction system was shut down on November 21, 1991 on <br /> completion of operation under Initial Variance 491-19 and 90 day <br /> Variance #91-20 A total of 13 , 116 pounds of gasoline range <br /> hydrocarbons were removed from the soils and ground water beneath <br /> this site by that time <br /> The vadose zone vapor recovery wells (PI, P3-Swarm and EX) <br /> contributed little to the total recovered hydrocarbons during <br /> this time period P1 = 1 . 3 pounds, P3-Swarm = 561 .4 pounds and <br /> EX = 127 pounds . <br /> The system was restarted under the Authority to Construct Permit <br /> (AP 91-106) on March 31, 1992 <br /> page 2 <br />