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yt <br /> ':JAL I_n1_F (ili lLYYi��hl;5�7C I1iT E`...VA <br /> , ENVIRONMENTAL SITE EVALUATION <br /> fATHROP PROPERTY <br /> WKA No, 1184.02 <br /> September 21, 1990 <br /> t'Z Page 2 <br /> 1� <br /> Phvslographic Setting <br /> n <br /> The subject property consists of approximately three acres of nearly square-shaped, relatively <br /> level land comprising one parcel at the northeast corner of Harlan and East Thomsen Roads,San <br /> Joaquin County, California. Surface soils are brown silty sands; the property had been disced, <br /> with only a sporadic covering of dried weeds and thistles up to 18 Inches high. Surface elevation <br /> is approximWely 15 feet above sea level. The property is bounded to the north by an individual <br /> residence; to the south by Thomsen Road, beyond which is a vacant lot; to the east by a <br /> l . residential subdivision; and to the west by Harlan Road, beyond which Is the Interstate 5 <br /> easement. <br /> { n FIELD INVESTIGATION <br /> �.n <br /> 3 Soli Borings <br /> Seven soil borings (P1 through P7) were drilled on-site during our investigation using a Mobile <br /> " B53 drill-rig equipped with six-inch diameter hollow-stem augers. Boring locations were selected <br /> on the basis of historical data review and on the findings generated during our Initial z;ubsurface <br /> evaluation of the property. The soil borings were drilled to a maximum depth of 15 feet below <br /> existing grade; contaminated soil cuttings generated during drilling were placed in a <br /> DOT-approved drum for on-site storage. A two-foot "plug" of bentonite pellets was placed at the <br /> bottom of each boring;the pellets were saturated with potable water and each boring was then <br /> I backfilled with a cement/bentonite slurry mix subsequent to drilling operations. A representative <br /> of San Joaquin County was on-site to observe the grouting procedure. <br /> r a Soil Sampling <br /> Soil samples were obtained at various depths within the borings utilizing a modified California <br /> ff = sampler containing two-inch diameter clean brass tubes; all samples were sealed with aluminum <br /> k<, foil, plastic end caps and tape, and preserved on ice to mitigate volatile hydrocarbon loss. The <br /> samples were delivered under chain-of-custody to a California-certified analytical laboratory for <br /> analysis of total petroleum hydrocarbons (TAH), benzene, toluene, xylene and ethyl benzene <br /> (BTX&E), tetraethyi lead, and ethylene dibromide. <br /> r. <br /> Ground Water Sampling <br /> A ground water sample was obtained from boring location P1 through the hollow-stem augers <br /> with single-usage polyethylene bailers; the sample was decanted into the appropriate glass <br /> containers, preserved on Ice and submitted to the laboratory for analysis of TPH and BTX&E. <br /> t� <br /> t� <br />