ARCHIVED REPORTS_XR0002514 - Laserfiche WebLink

Home Browse Search

of[Mlel_-_I HNfN Mr. Charles Leubner 10 October 1991 Page 5 Soluble lead was determined using the Waste Extraction Test (WET). The results of the soil sample analyses are presented in Table 1. Laboratory analytical reports for the soil samples are included in Attachment B. In the soil samples submitted for analyses from the three borings, total petroleum hydrocarbons as gasoline (TPH-G), and benzene, toluene, ethylbenzene, and xylenes (BTEX) were detected only in samples from boring B-1. The highest concentrations were detected in the sample collected at a depth of 10 feet below the ground surface (sample No. 132). Total petroleum hydrocarbons as gasoline were detected in this sample at an average concentration of 1,770 mg/Kg, and ethylbenzene and xylenes were detected at concentrations of 42,000 ug/Kg and 350,000 ug/Kg, respectively. This sample was submitted for analyses based on field screening results (i.e., degree of staining and OVA measurements greater than 1,000 ppm), which indicated that it potentially contained the highest concentrations of petroleum hydrocarbons encountered while drilling at the site. Concentrations of petroleum hydrocarbon constituents, as indicated both by OVA measurements and analytical results, decreased rapidly downward from the ten-foot depth. Although it was not analyzed, the sample collected at a depth of 15 feet had an OVA headspace reading of 80 ppm as methane indicating that petroleum hydrocarbons may have migrated to that depth. Concentrations of total petroleum hydrocarbons as gasoline in the sample collected at a depth of 20 feet (sample No. 134) were below the laboratory's limits of detection. Because this sample was selected for analysis after we received the results of the analysis of samples collected at depths of 10, 30, 40 and 50 feet, the sample was analyzed several days after the expiration of the holding time. However, we feel that the data from the analysis of the 20-foot sample is a valid indication that the majority of the petroleum hydrocarbons are above the depth of 20 feet. CONCLUSIONS Petroleum hydrocarbons identified as gasoline, and the petroleum constituents toluene, ethylbenzene, and xylenes, are present in the soil beneath the former location of the gasoline tank. Based on the results of the soil borings drilled at the site, the areal extent of these petroleum hydrocarbons appears to be limited to the area immediately beneath the former tank, as no petroleum hydrocarbons were detected in the soil samples collected from either Boring B-2 or B-3. Although the fourth soil boring was not drilled to the southeast of the excavation as planned, based on the lithology observed in the three boring that were drilled, it is