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' 4D h4 KLEINFELDER was noted on the surface of groundwater within the excavation. Observation of petroleum odors from the water was not reliable due to the masking effect of petroleum-like odors noted from excavation of petroleum affected soil. 6.1.3.2 CONFIRMATION SAMPLING Kleinfelder collected and analyzed 31 soil samples in and around this larger excavation. Eighteen ' of these samples were collected within LE-C. Eight (8) of these 18 confirmation samples were taken in soil that is currently stockpiled next to LE-C. Six of these 8 samples were collected in discolored soil to assess potential contaminants and for correlation with field observations. These ' five samples include sample numbers 21987, 21978, 21977, 21976, 24111 and 23710. The results of these six soil samples show that both purgeable and extractable hydrocarbons were ' present in excavated soil from LE-C. TPH-P, toluene, ethylbenzene and xylenes were detected as well as TPH-D and oil and grease (see Table 2). Four of five LUFT metals (Cr, Pb, Ni, and Zn) ' were detected, but at concentrations below the TTLC and STLC Regulated Level for classification of the metals as a hazardous waste per California Code of Regulations 22CCR §66261.24. PCBs were analyzed for in one of these five samples in discolored soil at a depth of ' about 7 feet bgs. PCBs were not detected at or above laboratory reporting limits. During excavation of LEC a total of 18 sidewall samples were collected. Soil in the area of 8 of these sidewall samples were subsequently excavated. Therefore 10 of the original sidewall ' samples were taken from the sides of the excavation as they existed on July 3, 2001. As previously noted, field observations showed that the eastern, southern and western sidewalls appeared clean. TPH-P and BTEX constituents were not detected above laboratory reporting limits for each of these 10 sidewall samples (See Plate 2), including the two taken in the northern sidewall where discolored soils were noted. However 3 of these 10 current sidewall samples ' show concentrations of oil and grease ranging from 114 to 1,170 mg/kg. The highest concentration of O&G of 1,170 mg/kg was noted in an eastern sidewall sample where no discoloration or odor was noted. In contrast only one of two northern sidewall samples taken in discolored soil with petroleum odors, and had an oil and grease concentration at 114 mg/kg. Two soil samples exhibiting the highest O&G concentrations (collected along the eastern sidewall and an former interior sample) were additionally run for TPH-D and TPH-O. TPH-D ' was detected at 1.1 mg/kg in an interior sample. The existing eastern sidewall sample (23707) with an O&G concentration of 1,170 mg/kg had no detectable TPH-D and TPH-O. ' The O&G analyses by Standard Method 5520 is often a recommended method by several regulatory agencies and therefore was included in the analytical suite in this project. However, this analyses can be subject to errors, primarily false positive results. ' The following quotes were stated within a book titled "Standard Methods for the Examination of Water and Wastewater", prepared by The American Public Health Association, American Water Works Associating, and Water Pollution Control Federation. This document states "In the determination of oil and grease, an absolute quantity of a specified substance is not measured.... ' It is important to understand that, unlike some constituents that represent distinct chemical 20-4341-1 I.E01/201 IR959 Page 26 of 31 ' Copyright 2001,Kleinfelder,Inc. August 21,2001