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IMs Mary Meays Page 4 March 3, 1997 Former Tank Site #2 As presented in Table 2, as in past sampling events, TPH(g) was only detected in samples collected from MW-1A (9 6 mg/1) and MW-2A (0 600 mg/1) TPH(d) was detected at lower concentrations in all five wells ranging from 0 045 mg/l (MW-4A) to 2 0 mg/l (MW-1A) A few of these TPH(d) detections represent first time detections for the associated wells, several are close to the detection limit and may not be reliable BTEX compounds were only detected in MW-1A, which f is located in the immediate vicinity of the former tank These BTEX detections are slightly higher than the last quarterly monitoring results (March 7, 1996),but are consistent with previous results As noted above, the water quality results presented in Table 4 are considered baseline and will be compared to future monitoring results to evaluate the effectiveness of the ORC process Of the five wells at this site, well MW-2A has anomalous readings for several parameters ERM believes that the elevated pH, which has been observed during previous monitoring events, indicates the presence of unusual conditions at that well One possible explanation 1s that grout, as occasionally occurs during installation, may have come into contact Iwith the screened interval of that well ERM is concerned that the elevated pH conditions in the immediate area of MW-2A may not be conducive to microbial y activity, even if the oxygen content were to be increased The heterotropic plate rcount results under current (pre-ORC) conditions indicate a low level of microbial activity for MW-1A and a non-detectable level of activity at well MW-2A, which is consistent with this concern The impacts of the elevated pH associated with MW-2A should be limited to the immediate vicinity of that well, as evidenced by the neutral pH detections currently and historically associated with all of the other wells CONCLUSIONS As in past sampling events, TPH as gasoline and diesel, and BTEX compounds were detected in ground water at the Catellus properties located at 1325 and 1515 West Weber Avenue At Former Tank Site 1, consistently with historical results, TPH(g) and BTEX detections are associated with MW-4 and MW-5, TPH(d) was falso detected in all five wells at low concentrations At Former Tank Site 2, TPH(g) and BTEX were detected in MW-1A, TPH(g) compounds were detected in MW-2A, and TPH(d) was detected in all five wells at low concentrations At both locations the concentrations in ground water are generally low, except in the immediate vicinity of the former tanks where elevated chemical detections have I been observed historically The consistency with historical results indicates that the plumes do not appear to be migrating Bioremediation appears to already be occurring at the two sites as indicated by the heterotropic plate count results for � v t