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t `Mr Michael Collins September 3, 1993 Page 3 • _ - Northeast Corner. Soil samples NEW-10, ENW 17, and BNE 28, were collected from the northeast comer of the excavation at depths of 10 feet, 17 feet, and 28 feet bgs, respectively Analytical results of soil sample NEW-10, collected at 10 feet bgs, identified TPH-D at a concentration of 220 parts per million (ppm) and TPH-MO at a concentration of 440 ppm Soil samples ENW-17 and BNE-28 did not identify TPH-affected soil at their respective depths, therefore, the excavation did not exceed 28 feet bgs in the northeast corner Northwest Corner. Two soil samples,NNW-7 and WNW-7, were collected from the northwest corner of the excavation at a depth of approximately 7 feet bgs Laboratory analysis of soil sample NNW-7 identified TPH-D at a concentrations of 26 ppm, and TPH-MO at a concentration of 65 ppm Hydrocarbon constituents were not identified in soil sample WNW-7 The excavation was extended to a depth of approximately 28 feet bgs based on visual identification of affected soil No additional soil samples have been collected from this area at this time Northern Wall. Soil samples WN-10, NW-26, and NB-M-44 were collected along the northern perimeter of the excavation TPH-D and TPH-MO have been identified in all three samples at concentrations ranging from 160 ppm to 2,900 ppm Analytical results also identified total xylene isomers in the soil at a depth of 44 feet bgs . Stockpile The three soil samples collected from the stockpile were collected from areas which were visibly affected by petroleum constituents Analytical results indicate that the three samples had flashpoints greater than 140°F and pH values of 8 3 to 8 4 Reactive sulfide and reactive cyanide were both below their respective analytical method reporting limits in all three samples Results of the fish bioassay indicated a survival rate of the fish ranging between 85 to 95 percent with the lowest survival rate of any single test being 80 percent Conclusions and Recommendations The following conclusions and recommendations are based on visual inspection of the excavated material and laboratory results of soil samples collected from the excavation Conclusions. Analytical laboratory results indicate that the material being excavated is nonhazardous in accordance with Title 22, Article 3, Chapter 11 The samples collected for this determination were collected from areas which, from a qualitative standpoint, would produce a "worst case" sample Recommendations. BC recommends backfilling the excavation with the stockpiled material and returning the site to its original (pre-excavation) condition Prior to backfilling the excavation, BC recommends the collection of additional soils samples in order to document the concentrations of TPH in soil at the limits of the excavation BC recommends the collection of 12 additional soil samples 5 from the north, west, and south sidewalls, and 7 from the western half of the bottom of the excavation (Figure 2) Actual sampling locations Use or disclosure of data contained on this sheet is subject to the restriction specified at the beginning of this document Brown and Caldwell 7603\CORRESPA7603 02 L 1 Consultants