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AWAWANAM <br /> Project Status Update Report, Site Code 1988 <br /> • Holt Brothers Tractor Company, W0402 <br /> 1541 West Charter Way, Stockton, CA <br /> October 6, 1992 <br /> Groundwater elevation data indicates groundwater flow beneath the site is toward the southwest, <br /> with a hydraulic gradient of 0 008 ft/ft or approximately 42 4 feet/mile Monitoring wells MW2 <br /> and MW3 are not included in the groundwater gradient calculation due to their partial <br /> penetration through the zone of saturation (Table 2) This gradient is consistent with <br /> observations presented in earlier Dames and Moore reports A groundwater gradient map is <br /> included on Figure 3 <br /> Groundwater samples were collected from wells MW4, MWS, and MW6, after purging at least <br /> three casing volumes of water or until the well went dry Each well was allowed to recovery <br /> at least 80% prior to collecting a groundwater sample Floating hydrocarbon product in well <br /> MW-1 was measured to be approximately 0 03 feet in thickness No sample was collected from <br /> this well No samples were collected from wells MW2 and MW3 due to lack of water MW2 <br /> and MW3 contained 0 36 and 0 49 feet of standing water respectively The monitoring wells <br /> were purged and sampled according to RESNA's Quality Assurance/Quality Control Plan <br /> (Attachment 1) Well purge logs are included as Attachment 2 <br /> LABORATORY ANALYSIS <br /> The groundwater samples were submitted to Sequoia Analytical Laboratory (Redwood City, CA) <br /> for analysis of benzene, toluene, ethylbenzene, xylenes (BTEX) utilizing EPA method 8020, <br /> total petroleum hydrocarbons as gasoline (TPHG) and as diesel (TPHD) utilizing EPA method <br /> 8015 modified, and halogenated volatile organics utilizing EPA method 8010 <br /> Laboratory analysis of the sample collected from well MW-5 indicate the presence of benzene <br /> (1 4 ppb), apparent TPHG (65 ppb), and apparent TPHD (100 ppb) Review of the <br /> chromatogram from sample MW-5 indicates a non-gasoline compound and a non-diesel mix <br /> patterns in the respective carbon ranges of gasoline (C4 - C12) and diesel (>C12) Halogenated <br /> volatile organics detected in sample MW-5 include 1,4-dichlorobenzene (4 5 ppb), 1,2- <br /> dichlorobenzene (8 0 ppb), cis-1,2-dichloroethene (1 2 ppb), trans-1,2-dichloroethene (2 7 ppb), <br /> and trichloroethene (3 8 ppb) All detected analytes, with the exception of benzene, are below <br /> California's primary maximum contaminant level (MCL) for drinking water standards <br /> LRO82892 FNL 2 <br />