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' Boyett Petroleum January 15, 2001 4.19 South Main Street, Manteca, California Page 3 Interim Report of Findings for Lateral Extent of Groundwater Contamination 3.0 Scope of Work This scope of work was developed to explore the lateral and vertical extent of groundwater ' contamination at Boyett Petroleum in Manteca, California. Soil contamination was not present in any of the soil samples collected from the new borings/monitoring wells. ' On December 20-22, 2000, WIN, Inc., in conjunction with Frontier Drilling, a state licensed drilling contractor, completed four (4) soil borings, that were converted to monitoring wells, to a depth of approximately 26.5' bgl (groundwater depth --17') to ' confirm the presence or absence of petroleum hydrocarbons and the vertical extent of the soil contamination in the unauthorized release area. The actual depth of the wells varied between 20' and 25'. This event provided further data to evaluate the soil contamination, and the extent of groundwater contamination underlying the site. Soil samples were taken from all four (4) borings at five (5) foot intervals for soil classification. Three (3) soil samples were selected from each boring at depths of 16-16 1/2 feet, 20-21 1/2 feet, and 26-26 1/2 feet for laboratory analysis. Each boring was converted into a monitoring well. ' A total of twelve (12) les were taken and analyzed using EPA method 5030/LUFT ( ) soil samples for gasoline petroleum hydrocarbons, EPA method 8260B for BTX&E compounds, oxygenates, Ethylene Dibromide (EDB), and 1,2-Dichloroethane (1,2-DCA). The soil sample analysis indicated no detectable levels of Petroleum Hydrocarbons as Gasoline, t BTXE, oxygenates, EDB, or 1,2-DCA in the twelve (12) soil samples collected from the borings/wells (Table 1 and Appendix B). The locations of these new monitoring wells are shown in Figure 3 and are described below: • MW-5 was placed southest of MW-2, near Main Street ' • MW-6 was placed southwest of MW-1, behind the Mini-Mart MW-7 was placed west of MW-1, on the northwest end of the property • MW-8 was placed off-site, north of MW-1, across Wetmore ,Street ' The data collected during scope a of work was used to define the migration of the p groundwater plume, and to make recommendations regarding future work at this site. A ' revised Report of Findings will be submitted at a later date and will include Cone Penetrometer Technology (CPT) data, as well as the installation of a deep well extending k-Irviv the arnnndwater table. following the results of the CPT test.