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'f Pombo Ranch Facility April 24,2005 Remedial Excavation& Source Removal Well records for all wells within a 2000-foot radius of the site were requested from the Department of Water Resources. Water Resources reported records of several wells in the northwest quarter of section 30 Township 2South / Range 5 east but no wells records for wells within 2000 feet of the site. There were no well completion reports on file for the three domestic wells identified in an earlier receptor survey and shown on Figure 1. Construction details have not been recovered for the nearby wells and the well is reported to not been serviced for many years. 2.0 SCOPE OF WORK ' On February 8, 2005 M.J. Kloberdanz & Associates collected soil samples in the area proposed for excavation to pre-qualify the soil to be excavated for disposal at Forward ' Landfill. Four soil samples were collected at varying depths to provide an estimated average concentration of the petroleum contamination present in the soil near the original release at the Pomba Facility. The laboratory report and Forward Landfill Pre- Qualification Application are presented in Appendix A. A backhoe was provided by Pombo Ranch to facilitate sample collection. Gasoline, gasoline constituents and diesel were present in low to moderate levels in some of the samples. Lead concentration was consistent with normal background levels in the area. MTable of Analytical Results 02/08/05 Sample Gasoline TEPH Benzene Toluene E-Benzene Xylenes Lead ' I.D. mg/KS mg/KSm /Kg pg/Kg AgLES /K m PQ-1-5' <1.0 <1.0 <5.0 <5.0 <5.0 <5.0 5.7 P9-3-8' <1.0 <1.0 <5.0 <5.0 <5.0 8.1 6.0 ' PQ-3-5' 302 652 247 2320 1470 4030 7.8 PQ-3-8' 2.7 1 37 <5.0 10 24 134 5.9 On February 28, 2005 M.J. Kloberdanz & Associate started the excavation of the source area of contamination closest to the former underground gasoline tank. A Photo Ionization Detector was used to screen contaminated soils from clean soils and to assist in worker health and safety. The impacted soils exhibited a dark gray discoloration and gasoline odor, which was confirmed with the Photo Ionization Detector. Soils near the original release were impacted below a depth at about 5 feet below grade. Away from ' the point of release, the depth to impacted soils increased to an average of 8 feet below surface grade. Soils above 8 feet in depth were then segregated into a "clean pile" for reuse as fill in the excavation. ' Groundwater was measured at a depth of about 12 feet from the surface in the January 2005 quarterly monitoring event. Depth to water was estimated at least 12 feet from ground surface in the area of the former UST on February 28th limiting the vertical extent of the excavation to 12 feet below grade surface. 6 1