ARCHIVED REPORTS_XR0010630 - Laserfiche WebLink

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Chemical Analysis and Results Chromalab Inc tested the groundwater samples using EPA Methods for Total Petroleum Hydrocarbons as Gasoline (TPHG), Benzene, Toluene, Ethylbenzene and Xylene (BTEX) and fuel oxygenates including Methyl-tert-butyl-ether (MTBE) The analytical reports are attached, and the results are listed below in Table 2 (see Table 3 for historic data) Table 2. Groundwater Chemical Data Well No Date TPHG' Benzene Toluene Ethylbenz Xylene Fuel Ox u g/l MW-1 12/10/97 — 530 55 350 440 NO MW-2 12/10/97 NO NO NO NO NO 59# MW-3 12/10/97 NO NO NO NO NO NO MW-4 12/10/97 NO NO NO NO NO NO Blank 12/10/97 NO NO NO NO NO NO NO- None detected NA-Not Analyzed ug/I - micrograms per liter Fuel Ox -Fuel oxygenates by Method 8260 #-MTBE "-TPHG not reported for MW-1 since laboratory used excess sample quantity on 8260 Discussion Groundwater flow direction appears consistent with historically observed trends The concentrations in Well MW-1 reflect an increase of levels of BTEX, and are attributed to residual contaminants being flushed into the groundwater from the soil strata in the immediate vicinity of the former tank pit Well MW-2 revealed that MTBE was detected for the first time Tetrachloroethene and 1,2-Dichlorethene (CIS) were observed for the first time in wells MW-2 and MW- 3 The source of these contaminants is unknown and they are present at very low concentrations fust above detection limits Monitoring Schedule The quarterly monitoring for this site is scheduled to continue at quarterly intervals it is our understanding that the San Joaquin Valley RWQCB has requested that all fuel oxygenate compounds be chemically analyzed by EPA Method 8260 in the future, and Wright will continue the addition of those compounds to the program for the next sampling Limitations This report has been prepared specifically for the M & M site at 60 E 10th Street, Tracy, CA, and was done according to the State and local agency suggested guidance documents for