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EL RANCHO ROCK & SAND, INC. QUARRY INVESTIGATION REPORT SLAB-1 SITE PAGE 3 3.3 Field Screening Field screening of the potentially contaminated soil was conducted to assist in evaluating the limits of any potential contamination, for the "Type 1 Contamination" encountered. Screening methods consisted of: a Visual inspection for evidence of hydrocarbon or other staining. • Head space analyses using field detection equipment (OVA-FID). — Calibration records are maintained for all field screening equipment, and are on file at Condor's Turlock office. Detailed field notes and records of field screening have been maintained. Photographs and videotape logs of the area have also been recorded. The apparent contamination was observed within a processed gray sand material that overlies light brown native soil. The gray sand at the location in question is several inches to possibly up to 1-foot in thickness. The apparent contamination was not observed in the underlying native soil. FID readings were collected in a grid pattern to delineate the area of potential contamination (see Figure 4). On April 15, 1994, the readings ranged from 0 to 1650 ppm, in a fairly well defined area. The area was covered with black plastic sheeting, pending laboratory analytical results. FID readings were repeated on April 19, 1994 after inconclusive analytical results were received, and additional sampling was warranted (see below). An FID reading of 7 ppm was recorded in the headspace under the plastic sheeting. FID readings from the potentially contaminated soil were sporadic and significantly lower than those recorded previously, with most readings being below 10 ppm and ranging up to a maximum of 150 ppm in only one location. Very few areas were found where any readings could be recorded, and readings would typically be lost when the FID was moved more than a few inches from the location where readings were recorded. 3.4 Sampling Samples were collected from the areas with the highest FID readings (see Figure 5). These samples were collected and prepared for immediate laboratory analysis, to determine if actual contamination exists, i.e., if the sample collected can be classified as a hazardous waste or hazardous material as defined by California law. While awaiting return of sample results, the contaminated soil will be covered, and left in-situ protected from volatilization. �- Four sets of samples were collected, two sets each on April 15 (A-1, A-2 & B-1, B-2) and April 19, 1994 (C-1, C-2 & D-1, D-2), at the locations shown in Figure 5. Samples were collected X44 W_ n 3.1 CONDOR