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NELSON READY MIX Report of Contaminated Soils Excavation Page: 5 are on Figure 2 The value listed for Pile 2 is a simple arithmetic average of the two laboratory values given in the table of laboratory results The total weight of diesel 1.7 removed by the excavation is calculated to be 3370 lbs The difference between the two calculations can be accounted for in a number of ways The highest levels of diesel from the Wright drill holes were from samples taken very close to the water table In the excavation, a product sheen was noted in the water seeping into the pit Consequently, these samples are probably not representative of the diesel level in each of the cells as a whole If, for example, the values for diesel in the 15 foot deep ' samples in each of the three drill holes (SB -- 1, SB — 2, SB — 7) are cut to 4100 ppm (which is the value found in sample G-5), the total weight of diesel present, in situ, becomes only 3556 lbs of diesel, close to the amount actually recovered The samples from the piles of contaminated soil were all taken from near the surface and some of the higher concentrations may have been deeper in the stockpile Also, some of ' the contaminated stockpiles had been on the surface for a number of days This may have led to some loss by evaporation I The water removed from the excavation and stored in above ground containment has been treated by carbon filtration and re-sampled The original concentration of diesel at 38 mg/L (ppm) appears to have been reduced to 1 3 mg/L in the sample obtained by GeoAnalytical Laboratories of July 6, 1999 PETROLEUM LABORATORY SAMPLE RESULTS FROM WATER TANK ' Diesel Benzene Toluene E benzene Total Xylenes MTBE (PPM) (PPB) (PPB} (PPB) (PPB) (PPB) 21-Junl 1 381 N01 Np ❑71 3 2 19 6—Jud 1 31_ NOI ND _______NDI NDJ NA ' ND—None Detected NA=Not analyzed 2.1 Soil Sampling ' The general lithology of the excavation was determined by a registered professional using the Unified Soil Classification System The same registered ' professional supervised the final portion of the excavation and the laboratory sampling ' All soil and groundwater sampling equipment was thoroughly washed with TSP solution and rinsed before and between sampling to prevent cross contamination ' The laboratory samples did not have head space and were immediately sealed in their containers The samples were then transferred to an ice chest containing blue ice and transported immediately to GeoAnalytical Laboratory under chain of ' custody Laboratory soil samples were analyzed using EPA method 3510/LUFT for diesel range petroleum hydrocarbons, EPA method 8020 for BTEX compounds & MTBE, Method 8260 for Oxygenated Compounds and Method 9040 for pH