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Monitoring Wells MW#4S and MW#4D were installed on the east side of Wilson Way in September of <br /> . 2000 Also,monitoring wells M W#5D,MW#6S and MW96D,MW#7S and MW#7D were installed north <br /> and south of the pump islands in September of 2000 (see attached Site Map) <br /> Monitoring wells MW#8S and MW8D were installed in a single bore hole inside the existing building,west <br /> of the pump islands on October 3, 2000 <br /> FIRST QUARTER 2002 MONITORING WELL SAMPLE ANALYSIS REPORT <br /> Sampled 02/13/02 <br /> WATER ANALYSIS OF SAMPLES FROM MONITORING WELLS <br /> On February 13, 2002, Del-recti Geotechnical Support Services extracted water samples from each <br /> monitoring well using standard industry practices under the supervision of Foothill Engineering A report <br /> of this work by Del-Tech Geotechnical Support Services is attached and is a part of this report The water <br /> samples were transported on ice by chain of custody to Sherwood Labs for analysis by Method SW802OF <br /> for BTEX,and TPHg Samples ofeach set of groundwater extractions were forwarded to Entech Analytcial <br /> Labs of Santa Clara,Ca for analysis by EPA Methods 8260FA and E200 7 Samples extracted for Soluble <br /> Lead analysis were made unusable for that analysis by an acid preservative in the sample container As a <br /> result of this preservative,the samples were analyzed for Total Lead and are shown as such on the recap sheet <br /> attached Future samples for lead will be extracted in containers without preservative <br /> FINDINGS FROM GROUNDWATER SURFACE DETERMINATION <br /> . The groundwater elevation on this site has raised 3'from the measurements done on December 12,2001 and <br /> is about 3 4'lower than in the first quarter of last year The slope of the groundwater gradient for this event <br /> is down slope to the northeast at S = 0 0018 <br /> FINDINGS FROM MONITORING WELL SAMPLE ANALYSIS FOR BTEX AND TPHg <br /> The concentration ofTPHg in monitoring wells MW#1,MW#3,MW#6S,MW#7S,and MW#8S are higher <br /> than last quarter All of the remaining monitor wells indicate concentrations of TPHg in the same range or <br /> lower than the last quarter MW#4D, MW44S, MW#6D, and MW#7D are non-detect for all analyzed <br /> hydrocarbon compounds this quarter <br /> FINDINGS FROM MONITORING WELL SAMPLE ANALYSIS FOR OXYGENATES <br /> At the request of the PHS/EHD samples from this event were analyzed for oxygenates by EPA method <br /> 8260FA including 1,2-Dichoroethane and 1,2-Dibromoethane Groundwater samples from MW#1,MW#2, <br /> MW#5D,MW#7D,MW98D,and MW#8S contained 1,2-Dlchoroethane in concentrations up to 1500 ug/L <br /> The groundwater sample from MW#1 contained 1,2-Dibromoethane at a concentration of 240 ug/L and <br /> TAME in concentrations of 260 ug/L <br /> FINDINGS FROM MONITORING WELL SAMPLE ANALYSIS FOR TOTAL LEAD <br /> All ofgroundwater samples extracted from the existing monitoring wells,with the exception ofMW#4S and <br /> MW45D had low concentrations of Total Lead Total Lead is the total both soluble lead and insoluble lead <br /> CONCLUSIONS <br /> • The water table elevations on this site continue to fluctuate as high as six feet per quarter On similar sites <br /> in Stockton, the water table elevation varies no more than two feet between quarters High volume <br /> agricultural pumping offsite most likely is the reason for this large variation in water surface elevations Low <br /> concentrations ofTotal Lead are normal for the Stockton area soils and should not be considered hazardous <br /> 2 <br />