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U 1,t ii r4 sm` H Approximately 0 01 feet of floating product/heavy sheen was measured in well MW 1 However, no product was able to be recovered from the well due to the small amount present Groundwater monitoring data since December 1990 are summarized in Table 1 A potentiometric surface map for the March 29, 1995 monitoring event is presented on Figure 2 Groundwater beneath the site generally flows to the southeast at an average gradient of 0 03 feet per feet (approximately 158 feet per mile) However, groundwater flow in the southwestern portion of the site (near wells MW1, MW5, MW6) appears to be to the northeast at a gradient of 0 025 feet per feet (approximately 132 feet per mile) Historically, groundwater elevation data has suggested an irregular groundwater surface beneath the site, possibly due to the heterogeneous nature of the soils and/or the varying well depths Groundwater samples were collected from wells MW2, MW3, MW4, MWS, and MW6, after purging at least three casing volumes of water or purging dry No sample was collected from well MW 1 due to the presence of free product/heavy sheen Monitoring wells were purged and sampled in accordance with the field methods included in Attachment 1 Well purge logs are included as Attachment 2 LABORATORY ANALYSIS Groundwater samples were transported under chain of custody protocol to Sequoia Analytical Laboratory in Redwood City, California (FLAP #1210) for analysis of benzene, toluene, ethylbenzene, and xylenes (BTEX) utilizing EPA method 8020, total petroleum hydrocarbons as gasoline (TPHg) and as diesel (TPHd) utilizing EPA method 8015 modified, and halogenated volatile organics (HVOCs) utilizing EPA method 8010 Laboratoryanalyses of each of the samples collected from the wells detected the presence of an Y p unidentified hydrocarbon in the TPHd range at concentrations ranging from 83 parts per billion (ppb) to 640 ppb The sample from monitoring well MW5 contained a detectable amount of benzene (2 4 ppb), ethylbenzene (0 74 ppb), xylenes (1 1 ppb) and TPHg (160 ppb) Analytical results of petroleum hydrocarbon constituents are summarized in Table 2 Laboratory data sheets and chat n-of-custody documentation are included in Attachment 3 The sample collected from monitoring well MW6 detected only one HVOC constituent, 1,2- Dichlorobenzene at 0 97 ppb Analyses of the sample collected from monitoring well MW5 detected several HVOCs including 1,3-Dichlorobenzene (1 9 ppb), 1,4-Dichlorobenzene (11 ppb), 1,2-Dichlorobenzene (22 ppb), cis-1,2-Dichloroethene (2 4 ppb), trans-1,2- Dichloroethene (3 2 ppb), and Trichloroethene (2 8 ppb) No HVOCs were detected in the samples collected from monitoring wells MW2, MW3 and MW4 Analytical results of 1500771QUARTLYIIQR-1995 dm 2