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t Ms. Margaret Lagorio September 24, 1996 Page 4 Ile events. As a result of active remediation at the site and nondetectable petroleum hydrocarbon concentrations, Municipal Well 12 was restarted on July 29, 1993. Additional monitoring wells (MW-2A and MW-2B) were installed to monitor the vertical extent of petroleum hydrocarbon impacted groundwater on site in June 1988. The migration of impacted groundwater beneath the Site towards Municipal Well 12 is monitored by wells W-2, W-5, and W-12. Since December 1994, as a result of active groundwater extraction and remediation at the site, BTEX and TPH-G concentrations in monitoring well W-2 are below analytical reporting limits (ARLs), with the exception of one isolated occurrence of total xylenes (1.9 milligrams per liter (mg/L)) on February 14, 1996. BTEX and TPH-G concentrations in W-12 have been below ARLS since February 1993, with the exception of an isolated occurrence of total xylenes (3.3 mg/L) on February 14, 1996. These isolated occurrences are explained in the following section: Nature and Extent of Petroleum Hydrocarbons in Groundwater. BC reviewed the well log for Municipal Well 12. The well log states that the total depth of the well is 490 feet, with the perforated interval starting at 210 feet bgs. The geology at the well includes approximately 40 feet of impervious strata (clay) from the ground surface. • Underground Utilities Underground utilities are not risk for migration of petroleum hydrocarbons at the Site. Petroleum-impacted soils at the Site are greater than 10 feet bgs. The underground utilities beneath the Site are less than 10 feet bgs. Maps of water, sewer, storm, gas, and electrical utilities are included as Exhibit C. Nature and Extent of Petroleum Hydrocarbons The following information summarizes the nature and extent of petroleum hydrocarbons at the Site. The information includes all historical results of soil and groundwater samples collected from the Site and surrounding area by BC. Soil. Analytical results of soil samples collected at the Site are summarized in Table 2. The analytical results indicate that petroleum hydrocarbons were present to a total depth of approximately 55 feet in the area of the pump island. Figures 7, 8, and 9 illustrate the extent of hydrocarbons in the soil prior to start of remediation. The constituents detected in soil were BTEX and TPH-G. Benzene concentrations ranged from below ARL to a maximum concentration of 220 milligrams per kilograms (mg/kg) in V-4 at 40 feet bgs. TPH-G concentrations ranged from below ARL to a maximum concentration of 17,000 mg/kg in V-4 at 40 feet bgs. • Use or disclosure of data continued on this sheet is subject to the restriction specified at the beginning of this document. 338 M ORRESAC LOSURE.DOC