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KLEINEELDER 5 DISCUSSION OF FINDINGS Soil samples submitted for analyses were selected based on the approved scope of work, field observations and PID readings. The type (composite and discrete) and number of soil samples submitted for analyses were conducted in an attempt to gather data to preliminarily profile petroleum impacted soil for disposal purposes and to assess the limits of petroleum impacted soil. Because of the nature of the 4-point composite samples collected for the purpose of potentially profiling the soil, field observations and PID readings were relied upon to a greater extent for assessing the vertical extent of petroleum impacted soil. Supplemental discrete soil sampling and analyses was conducted to assess the limits of petroleum impacted soil and for the purpose of correlating composite sampling and field observations. Based upon a relatively thicker transition zone noted between obvious petroleum impacted soil and estimated "clean" soil, ten additional discrete soil samples (included in the 26 discrete samples collected) were analyzed to assist in correlating field observations with analytical results and assessing vertical limits of petroleum impacted soil. 5.1 ANALYTICAL FINDINGS 5.1.1. Composite Soil Sampline Discussion Twenty two (22) composite samples were collected within the estimated footprint area. Discrete subsets of these composite samples were primarily collected within the depth interval of estimated petroleum impacted soil, although composite sampling was also conducted to a lesser degree in areas in which obvious petroleum impacted soil was not observed. Composite discrete sampling depths ranged from 1 to approximately 15 feet bgs. A few composite sets varied at depths ranging from 12 to 24 feet (PP6) and 5 to 35 feet (GP-1). Because of limited petroleum impact in the southern portion of the footprint area composite samples were collected at depths ranging from approximately 3 to 8 feet bgs and at times two of the shallower probes were used in a 4-point composite sample. When two probe locations were used to comprise a 4-point composite sample, the two locations were selected based on similar field observations, PID readings,proximity of probes, etc. The following are concentration ranges of the selected analytes for composite sampling: Analyte 'Concentration Range TPH-D ND <5.0 to 11, 000 m /ko TPH-O ND <5.0 to 4,900 mg/kg TPH-G ND <5.0 to 2,500 mg/kg Benzene ND <5.0 to 9,800 Toluene ND <5.0 to 31,000 Ethylbenzene ND <5.0 to 11,000 Xylenes ND <5.0)to 63,000 44843.T03/ST04RI025 Page 9 of 16 Copyright 2004 Kleinfelder,Inc. August 6,2004