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t f4, <br /> GROUND ZERO ANALYSIS, INC. <br /> 2291 W March Lane, Suite 127D <br /> Stockton, California 95207 <br /> Telephone. (209) 952-3481 <br /> Facsimile (209) 952-9891 <br /> January 17, 1996 <br /> Mr Harlan Knoll <br /> San Joaquin County Public Health Services <br /> Environmental Health Division <br /> P O Box 388 <br /> Stockton, CA 95201-0388 <br /> Subject Fourth Quarter 1995 Site Status Report <br /> Knowles Property, 1140 W Hammer Lane, Stockton, California <br /> Dear Mr Knoll <br /> This letter report summarizes fourth quarter 1995 activities at the subject site (Figure 1) <br /> Activities during the quarter included groundwater monitoring, well purging, and sampling for <br /> benzene, toluene, ethylbenzene, xylenes (BTEX), and total petroleum hydrocarbons as gasoline <br /> (TPHg) <br /> GROUNDWATER MONITORING <br /> Groundwater monitoring was performed on November 16, 1995 The depth to groundwater <br /> beneath the site ranged from 46 94 to 49 02 feet below grade Overall, groundwater elevations <br /> decreased an average of 0 15 feet since July 27, 1995 The groundwater flow direction at the <br /> time of measurement was generally to the southeast at hydraulic gradients ranging from <br /> approximately 0 003 to 0 008 feet per foot A groundwater gradient map for November 16, <br /> 1995 is presented on Figure 2 Groundwater monitoring data are summarized in Table 1 <br /> GROUNDWATER SAMPLING AND ANALYSIS <br /> Monitoring wells MW1, MW2, MW4, MW7, and MWS were purged and sampled on November <br /> 16, 1995 All purge water was contained on site in labelled drums approved by the Department <br /> of Transportation (DOT) Well purge logs are included in Attachment A Groundwater samples <br /> were submitted to Argon Laboratories (DHS Cert #1873) for analysis of BTEX and TPHg <br /> utilizing EPA methods 8020 and modified 8015, respectively <br /> TPHg and benzene were detected in well MW1 at concentrations of 920 and 43 parts per billion, <br /> respectively No petroleum hydrocarbons were detected in samples collected from wells MW2, <br /> groundzelknowles hamAgm1995 1 <br />,f <br /> I <br />