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Environmental Mr.Michael J.Infurna Resources 16 December 1998 Management Page 2 this operation were removed in September 1989. Approximately 16 cubic yards of hydrocarbon-impacted soil were removed and disposed off site. Three monitoring wells, MW-1 (RMC), MW-2 (RMC), and MW-3 (RMC), were installed in September 1991, and ground water was sampled for three consecutive quarters. The locations of these wells are shown in Figure 2. Available records indicate that these monitoring wells were abandoned in November or December 1992. In order to prepare the site for future residential use, several field investigations were conducted at the site by Industrial Compliance during the early 1990's. These investigations involved surface and subsurface soil sampling and the installation of two monitoring wells, MW-1 and MW-2 (Figure 2). During this series of site investigations, it was determined that lead was the only constituent of concern in site soil. Site remediation, involving excavation and off-site disposal of lead- impacted soil,was initiated in July 1995. By January 1996, it became apparent that an excessive amount of soil would require excavation and disposal to meet the regulatory criteria for residential use. At that time,SPTCo decided to cancel the sale of the property and eliminate, at least for the foreseeable future, possible residential use of the property. With the concurrence of the RWQCB,the remedial program was changed to on-site treatment of stockpiled lead- impacted soil and backfilling the existing excavation with the treated soil and clean imported fill. It is ERM's understanding that as a condition of this modification, the RWQCB required that four additional monitoring wells be installed within areas of former or still existing areas of lead- impacted soil on site (MW-3, MW-4, MW-5, and MW-6; Figure 2) and that ground water from all six monitoring wells be sampled and analyzed for dissolved lead for a minimum of three quarters. A detailed summary of the soil remediation program and documentation of the installation and construction of the new monitoring wells at the site are presented in a TerraNext(formally Industrial Compliance) report dated 9 August 1996 entitled, Site Soil Remediation Report, Southern Pacific Transportation Company, Old Tracy Yard, Tracy, California. Ground water monitoring in the wells between August 1992 and February 1997) demonstrated that dissolved lead was not detected at or above the reporting limit of 0.0050 mg/L in any of the six monitoring wells.