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. site would be required. Subsequently, on February 3, 1993, one 2-inch diameter groundwater monitoring well (MW-1) was installed at the site The well was initially sampled on February 9, 1993 Low concentrations of TPH as diesel and benzene (64 µg/1 and 0 4 N.g/l, respectively) were detected in the initial water sample. A second groundwater sample was collected in May 1993. No petroleum hydrocarbons were detected in the second sample A third water sample was collected on August 16, 1993. During the third round of sampling, TPH as diesel was detected at 68µg11 and benzene was detected an 0 3µg11 It as our understanding that no additional samples have been collected from MW-1 2.4 Groundwater Depth and Gradient Direction The depth to groundwater at the site is approximately 25 to 30 feet. No site-specific gradient data has been obtained However, according to information obtained from the PHS/EHD from nearby sites, the Iocal groundwater gradient direction is west or northwest However, City of Manteca Municipal Well #13 is located immediately west of the property and it is possible that this well may be influencing the gradient and flow direction at the site Without influence from the Municipal Well, the flow direction may be more southerly. 3.0 SCOPE OF WORK . In a letter dated November 17, 1994, the PHS/EHD stated that "at least two more monitoring wells must be located at the site, with one of the wells located between the former tank pat area and the municipal well " Therefore, GeoAudit proposed to install two additional monitoring wells at the site. One well wsil be located west of the main structure. (between the former tank pit and the municipal well) and the other well will be located southwest of the former tank pat area. The proposed locations of the wells are illustrated in Figure 2. 4.0 PROCEDURES To meet the project objectives, the following procedures will be performed. 1) Prepare a Site Health and Safety Plan in accordance with the Occupational Safety and Health Guidance Manual for Hazardous Waste Site Activities (Prepared by the National Institute for Occupational Safety and Health, Occupational Safety and Health Administration, U S Coast Guard and U.S. Environmental Protection Agency, October 1985). 2) Notify the San Joaquin County Public Health Services - Environmental Health Division (PHS/EHD) 48 hours prior to commencement of any work. CAL-WMT WnA NW_- 1-11 1Mf-M