|
ICanteen Facility July 10, 2001
<br /> Quarterly Groundwater Monitonng Report Page 3
<br /> IGroundwater Gradient
<br /> Interpretation of the monitor well gauging data indicates that there is a south
<br /> southwesterly hydraulic gradient across the Site of approximately 0 015 feet/foot Figure
<br /> 2 illustrates the groundwater contours and gradient for this gauging event The gradient
<br /> appears to be consistent with past gauging events The change in water levels is a result
<br /> of cyclical fluctuations in the weather and the proximity of the site to the Stockton
<br /> Diverting Canal, located approximately 1000 feet to the northeast The historical
<br />' groundwater elevations are summarized on Table 1
<br /> Groundwater Analytical Results
<br /> IGroundwater analytical results are compared to the California Department of Health
<br /> Services Drinking Water Standard Maximum Contaminant Levels (CAMCL) Analysis
<br /> I of the seventeen groundwater samples obtained from the on-Site monitor wells indicated
<br /> the following
<br /> • Benzene was detected in groundwater samples from monitor wells MW-1, MW-2,
<br /> MW-3D, MW-4, MW-5, MW-6, MW-13, MW-13A and MW-13B at
<br /> concentrations ranging from 14 to 27,000 gg/l, each exceeding the CAMCL for
<br /> benzene of 10 gg/l
<br /> • Toluene was detected in monitor wells MW-1, MW-2, MW-3A, MW-3D, MW-4,
<br /> MW-5, MW-6, MW-13, MW-13A and MW-13B at concentrations ranging from
<br /> 0 84 to 42,000 gg/l The CAMCL for toluene is 150 gg/l, exceeded only in MW-
<br /> 13
<br /> • Ethylbenzene was detected in monitor wells MW-1, MW-2, MW-3D, MW-4,
<br /> I MW-5, MW-6, MW-13, MW-13A, and MW-13D at concentrations ranging from
<br /> 0 54 to 4,300 gg/l The CAMCL for ethylbenzene is 700 gg/1, exceeded only in
<br /> MW-13
<br /> I • Total xylenes were detected in monitor wells MW-1, MW-2, MW-3D, MW-4,
<br /> MW-5, MW-6, MW-13, MW-13A, and MW-13D at concentrations ranging from
<br /> 0 79 to 25,000 gg/l The CAMCL for xylenes is 1,750 gg/L, exceeded only in
<br /> MW-13
<br /> • TPH(g) was detected in monitor wells MW-1, MW-3A, MW-31), MW-4, MW-5,
<br /> MW-6, MW-13, MW-13A, and MW-13D at concentrations ranging from 56 to
<br /> 220,000 µg/1
<br />
|