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= =C-L-E-A-4RWATER <br /> c, R O U P i INc <br /> E <br /> it v ro it m,mill Se r=tc<< <br /> 4.0 RESULTS <br /> 41 Water Level Gauging Data <br /> On March 21, 1997, the depths to groundwater in the six monitoring wells ranged <br /> from 14 89 to 15 76 feet below the top of casing Groundwater elevations, calculated <br /> for the purpose of estimating flow direction and gradient, were approximately five <br /> feet higher than groundwater elevations measured on November 14, 1996 The <br /> groundwater elevation contours shown on Figure 3 indicate that groundwater flow <br /> is toward the north and northwest The groundwater gradient is 0 0087 foot/foot <br /> (0 87%) across most of the site, but is only 0 0028 foot/foot (0 28%) between MW-1 <br /> and MW-6 This change in gradient appears as a flattening of the water table west of <br /> the former USTs, which is consistent with the configuration of the water table <br /> during previous gauging events <br /> On the basis of historic data, water levels at this site have risen approximately 9 feet <br /> within the past 3 to 4 years It should be noted that during the March 21, 1997 <br /> sampling event, well screens in 4 of the 6 monitoring wells were submerged by <br /> groundwater Water levels in the remaining two wells (MW-4 and MW-5) were <br /> near the top of the screened intervals <br /> 4.2 Groundwater Analytical Results <br /> TPHg and BTEX were not detected in concentrations exceeding the reporting limits <br /> in groundwater samples from monitoring wells MW-4 and MW-6 The samples <br /> from MW-1, MW-3, and MW-5 contained benzene concentrations up to 2 5 parts per <br /> billion (ppb) and TPHg concentrations up to 80 ppb The maximum concentrations <br /> of TPHg and BTEX were in the sample from MW-2 23,000 ppb TPHg and 130 ppb <br /> benzene <br /> MTBE was detected in the samples from MW-3 and MW-5 in concentrations of 10 <br /> ppb and 5 ppb, respectively The detection limit for MTBE was elevated to 50 ppb in <br /> the sample from MW-2 because of the high concentrations of target compounds <br /> A summary of groundwater elevations and analytical results is presented on Table <br /> 1 Hydrocarbon concentrations are presented graphically on Figure 4 Copies of the <br /> laboratory report and chain-of-custody form are attached as Appendix B <br /> D-101 1Q97 3 Apn1 15, 1997 <br />