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r { Quarterly Moattortng Report Heinz Facility,757 E 11th St ,Tracy September 4, 1992 Page 2 On July 29, 1992, groundwater monitoring was conducted at the site During monitoring, depth to water was measured, the wells were purged, and samples were collected from wells MW2 and MW3 Water levels had risen approximately 0 25 feet since the previous quarterly monitoring and sampling event in April, 1992 (Table 1). The gradient cannot be calculated specifically for this site because only two wells are accessible (Monitoring well MW 1 was previously inadvertently destroyed during paving activities). However, RESNA Industries has current monitoring data from the uppermost saturated zone at two Tracy sites within a one-mile radius of the subject site The local groundwater gradient can be established from July, 1992 monitoring data from 8181 Eleventh Street (Genstar Western Stone) and 6700 Grantline Road (J B Terminal) The site locations and gradient directions relative to the subject site are shown on Figure 3 The most recent groundwater gradient map and monitoring data for each site are included in Attachment 1 The gradients are essentially in a northerly direction There are no known surface or subsurface occurrences on site which would exert a significant influence on the direction of groundwater flow Therefore, even though the direction of flow cannot be specifically determined from the on-site wells, the direction can be safely assumed to be consistent with the nearby sites Monitoring well MW2 is appropriately located to monitor groundwater downgradient from the excavation and MW3 is adequate for upgradient observations The water samples collected from wells MW2 and MW3 were analyzed for benzene, toluene, ethylbenzene, xylenes (BTEX), by EPA method 8020, total petroleum hydrocarbons as gasoline (TPHG), and total petroleum hydrocarbons as diesel (TPHD) by modified EPA method 8015 Dissolved petroleum hydrocarbons were not detected at or above method detection limits in MW3 Xylenes (1 8 parts per billion - ppb) and TPHG (120 ppb) were detected in well MW2 Although xylenes were detected, levels are well below primary State and proposed EPA Maximum Contaminant Levels (MCL) or goals Previously petroleum hydrocarbons had not been detected above method reporting limits since July 1991 Detection during this round of sampling could possibly be related to the rise in water levels Water levels were within 0 3 feet of current levels when petroleum hydrocarbons were detected one year ago (July 1991) Analytical data is presented on Table 2 The laboratory data sheet, chain-of-custody, and monitoring data are included as Attachment 2 Petroleum hydrocarbon analytes have not been detected in well MW3 since July 10, 1992, therefore RESNA recommends, on behalf of our client, a cessation of monitoring/sampling of well MW3 Also we recommend a reduction of monitoring/sampling to a yearly schedule for monitoring well MW2 QR081792 DRF