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Jim Tjosvold, P.E. <br /> Page 2 <br /> April 29, 1988 <br /> chromium concentrations. Results from the current sampling <br /> displayed no hexavalent chromium. These samples were also <br /> analyzed for total chromium. A comparison (table 1) of past and <br /> current results indicate that the chromium concentration has <br /> decreased significantly. An explanation should be presented on <br /> this situation and also be projected for other metals at this <br /> site. <br /> Table 1 <br /> Previous Current <br /> Previous sample Current sample total total <br /> location (year) location chromium (ppm) chromium (Ppm) <br /> 7B 3-9" (1983) SA 13 0-12" 150 32 <br /> 7C 3-9" (1983) SA 14 0-12" 1320 740 <br /> 8B 3-9" (1983) SA 16 0-12" 252 35 <br /> 8C 3-9" (1983) SA 17 0-12" 148 30 <br /> B10 0-2 ' (1984) SA 15 0-12" 198 30 <br /> Lead Testing - Results show elevated levels of soluble lead in <br /> the track area, but do not require further investigation at this <br /> time. <br /> Task 8 - Offsite Pole Storage Area - The results conclude no <br /> organic and minimum metal contamination. <br /> Task 9 - Mormon Slough Sediment Sampling - <br /> Old Mormon Slough - A comparison on a dry weight basis showed <br /> metal results to be constant except for the last sample, OMS-5, <br /> which is lower. While Dutras Construction filed a permit to <br /> dredge their entire property boundary, the last information <br /> received by the Department states that dredging was only done in <br /> the center of their property line. If this information is <br /> accurate, then OMS-5 would have been taken deeper than the other <br /> samples. This may imply that OMS-5 is untainted, while OMS-1 <br /> thru 4 are elevated samples. Further evaluation may be <br /> necessary, based on the PHERA. <br /> New Mormon Slough - Samples at the discharge point (NMS-1) and <br /> 100 feet downstream (NMS-2) have elevated levels of arsenic, <br /> chromium, and copper. The results have been presented to the <br /> California Department of Fish and Game (DFG) . Their interest is <br /> if a level of soluable metals is present which could affect fish. <br /> To evaluate the availability of these metals for fish toxicity <br /> and bioaccumulation studies, DFG suggests these samples should be <br /> reanalyzed for soluble metals. To save costs, the original <br /> samples may be used for the analysis, noting that the sample hold <br /> times have been exceeded. <br />