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Beneath the Concrete Reservoir <br /> AENIC does not plan to excavate or advance boreholes beneath the concrete rese.voir. y,J <br /> There exists no evidence that the concrete surface is cracked and that fuel oil has <br /> contaminated soil beneath the reservoir. However, AEMC proceeded with site <br /> investization activities under the assumption that soils beneath the reservoir are <br /> contaminated with fuel oils. Due to the obvious physical limitations associated with <br /> characterizing soils beneath the reservoir, AEMC chose to investigate area groundwater as <br /> a valid indicator of significant sub-reservoir contamination. <br /> Under the jurisdiction of the Central Valley Regional Water Quality Control Board <br /> (RWQCB), AEMC established three groundwater monitoring wells and recently (February <br /> 1988) completed the quarterly/one year monitoring program required by the RWQCB. <br /> No degradation of groundwater quality was detected during the one{monitoring program, <br /> hence AENIC requested, by letter dated 7 March 1988, the RWQCB's review and <br /> determination of the water quality impacts at the Beck property. <br /> The RWQCB requested AENIC, by letter dated 4 April 1988, to extend the groundwater <br /> monitoring period an additional six months due to the significant shifts in the groundwater <br /> gradient over the one year period. The primary concern of the RWQCB is that the two <br /> downeradient wells "may" not be properly positioned to detect a plume of contamination <br /> from the Beck property, in which case a fourth well would likely be required by the <br /> RWQCB. Subsequent conversations with the RWQCB have indicated that the <br /> establishment of a properly positioned fourth monitoring well and <br /> subsequent sampling/analysis would provide the information necessary for t .e R;(CQ-B to <br /> accurately assess the water quality impacts. <br /> AEMC will establish two new groundwater monitoring wells (BD4 and BD5) downgradient <br /> of the concrete reservoir (refer to Figure 2). Monitoring Well BD4 will be constructed in a <br /> similar manner as the three existing monitoring wells, while BD5 will be constructed to the <br /> 30 to 50 foot depth in an effort to determine vertical gradients, if any. The directions of <br /> the groundwater gradient over a 1 1/2-year time period are displayed on Figure 3. Refer <br /> to Attachment 4 for a description of the well installation and development procedures to <br /> 5 <br />