ARCHIVED REPORTS XR0010524 - Laserfiche WebLink

Home Browse Search

concentrations are contoured in Figure 9 -Like the gasoline-range compounds, the extractable compounds are distributed in an elongate belt that trends northwest-southeast The plume in Figure 9 extends farther to both the northwest and southeast than the plume in Figure 5, because the 8015/3550 analysis detected hydrocarbons in both JLM-8-26' and JLM-11-26', whereas the 8015/5530 analysis did not 5.0 DISCUSSION AND CONCLUSIONS This phase of investigation had two primary goals 1)to delineate the extent of soil contamination and determine whether this contamination is indicative of a single source' or multiple sources, and 2) to locate the limits of groundwater contamination to determine whether additional monitoring wells are needed The results confirm that the first objective was achieved The second objective was achieved for some"but not all hydrocarbons Soil is impacted only at the north end of the station building Gasoline-range hydrocarbons have now been detected in three borings in this area(JLM-2, JLM-5, and JLM-9) in the general range of 10 to 30 feet, at concentrations ranging from 2 to 1,300 mg/kg (ppm) Hydrocarbons are absent in other borings located 30 to 40 feet from these borings The detected hydrocarbons cluster around the former product line that ran from the underground storage tank facility to the fuel dispensers The laboratory analyses indicate that benzene is absent and the concentration of other volatile aromatic hydrocarbons is low, leading the laboratory to suggest that the fuel is old and moderately degraded Groundwater is impacted over a larger area, but the concentrations are relatively low The area of highest concentration (1,000-3,000 ppb) appears to be located dust downgradient of the former product line Lower concentrations have been detected farther downgradient, as well as upgradient of the product line Gasoline oxygenates are slightly more widespread than other gasoline compounds, but the maximum concentration is probably in the range of 100 ppb in the southeastern portion of the site The northwestern limit of the plume is beneath the former underground storage tanks, the southeastern limit is probably beneath the sidewalk along EI Dorado Street Groundwater monitoring for the first quarter of 2003 is tentatively scheduled to take place in late March We do not recommend performing any additional work until after those samples have been analyzed, the First Quarter 2003 Report has been completed, and reimbursement for this phase of drilling has been received from the State Underground Storage Tank Cleanup Fund I