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UNOCAL Corporation March 9, 1994 Page 4 Cd, Cr (VI), WET Ni and WET Pb were not detected in soil sample UW-1 or the soil sample from Boring U-E Additional investigation of these metals in this area as requested in the SJCEHD letter is not warranted Cr (VI) and WET Ni were not detected in soil sample UW-2 or the soil sample from Boring U-A. However, Cd was detected in the soil sample from Boring U-A at a concentration of 1 1 parts per million (ppm), and no soil sample from this area has been analyzed for WET Pb Additional soil sampling in this area will be performed to comply with the SJCEHD letter To further assess the subsurface conditions and comply with the request for additional investigation made in the SJCEHD letter referenced above, GSI proposes to drill one soil boring to a depth of 50 feet bgs between Borings U-D 6 and U-F If groundwater is not encountere7ln ~this boring, no groundwater monitoring wells will be installed at the site, and subsequent borings will be . terminated at 40 feet bgs If groundwater is encountered, a groundwater monitoring well will be installed in this boring and at the two other monitoring well locations shown on Plate 2. Subsequent soil borings drilled in the vicinity of Borings U-C and U-D will be terminated at 40 feet bgs The boring adjacent to Boring U-A will be terminated at 11 5 feet bgs if the boring is not to be converted to a groundwater monitoring well In any event, one sample from this boring at 11 5 feet bgs will be analyzed for metals as described in Task 3 below GSI also proposes to drill one soil boring to ten feet bgs in the northwest corner of the site to collect a soil sample for the potential evaluation of background levels of various metals. This sample will be held at the analytical laboratory pending receipt of initial chemical analytical data This work will be performed according to the following scope of work TASK 1 Obtain the necessary well installation and soil boring permits TASK 2 Drilling Drill eight exploratory soil borings at the locations shown on Plate 2 using 8-inch-diameter hollow-stem augers driven by a truck-mounted rig A GSI geologist will monitor the drilling and 782790-4 GeoStrategies Inc.