|
SECOND QUARTER,2002
<br /> . GROUNDWATER MONITORING REPORT
<br /> USA STATION#110,STOCKTON
<br /> JUNE 2002
<br /> 3.1 Groundwater Flow and Gradient
<br /> On April 12, 2002, groundwater data collected at the site indicated that depths to groundwater
<br /> ranged from 58.55-feet below ground surface (bgs)in MW-3P to 59 25-feet bgs in MW-2P.
<br /> The groundwater elevations ranged from -33 50-feet below mean sea level(MSL)in MW-
<br /> 3P to -33 65-feet below MSL m MW-4P Groundwater elevation measurements indicate
<br /> groundwater was flowing to the southeast at a hydraulic gradient of approximately 0 0004-
<br />, foottfoot Groundwater elevations and gradient are shown on Figure 4.
<br /> A review of the histoncal field data suggests that the groundwater generally flows between
<br /> southeast and northeast Historical groundwater elevation data can be found m Appendix C, it
<br /> includes data before 1999
<br /> 3.2 Groundwater Analytical Results
<br /> For April 12, 2002, all petroleum compounds were non-detect(ND)at the method detection
<br /> limit in MW-4P TPH G was reported in samples from monitoring wells MW-2P, MW-3P,
<br /> MW-1 and MW-2 at 860 micrograms per literµg/l, 140µg/l, 460µg11 and 110µg11,
<br /> respectively Benzene was detected in samples from MW-2P and MW-1 at 44µg11 and 17
<br /> ,zg/l,respectively Toluene was reported in samples from MW-1P, MW-2P, MW-3P,MW-1
<br /> and MW-2 at concentrations ranging from 0 97µg11 in MW-1P to 9.2µg/1 in MW-1
<br /> Ethylbenzene was reported in the sample from MW-2P at 1 6µg/1 Xylenes were reported in
<br /> samples from MW-2P, MW-3P and MW-1 at 6 5 µg/1, 10 1-,g/1 and 1.8µg11, respectively
<br /> Using EPA Method 8020,MTBE was reported in samples from MW-2P, MW-3P,and MW-1 at
<br /> 140µg/l, 53 µg/l,and 170µg11, respectively Using EPA Method 826013,MTBE was reported
<br /> in samples from MW-1,MW-1P, MW-2P and MW-3P at 130µg/l, 0 57µg/1, 140 ugll and 44
<br /> µg11,respectively DIPE was reported in samples from MW-1P, MW-3P, MW-5P and MW-6P
<br /> at 23 µg11, 19µg11, 190,ugli and 8 1 µg11, respectively TBA was reported in samples from
<br /> MW-1 and MW-2P at 480µg/1 and 180 ug/1,respectively All other oxygenates were ND at the
<br /> method detection lumt for this sampling event. 1,2-DCA was reported in samples from MW-1,
<br /> MW-1P, MW-2P,MW-3P, MW-5P and MW-6P at concentrations ranging from 12 µg/1 in MW-
<br /> 6P to 12µg/1 in MW-5P The groundwater analytical results for this sampling event are
<br /> summarized in Tables 2 and 3, and shown on.Figures 5 and 6 A Copy of the laboratory report
<br /> with COC documentation is included in Appendix B Appendix D provides histoncal
<br /> groundwater analytical data from before 1999
<br /> 4.0 SCHEDULE
<br /> . The third quarter sampling event for 2002 will be conducted in July 2002 and the monitornng
<br /> report will be submitted within 30 days of the end of the quarter
<br /> 3
<br />
|