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LFR Inc. Based on these-results, it is apparent that pyrolytic oil has affected groundwater quality downgradient from the Site. Further details regarding the presence of dissolved pyrolytic oil constituents in groundwater north-northwest of the Site due to the melted tires are provided in Section 7.0 of this report. 5.5.5 Destruction of Well MW-6 Monitoring well MW-6 was located within the boundaries of proposed excavation activities at the Site. Excavation was proposed in the vicinity of well MW-6 to remove pyrolytic oil-affected soil that extended along the northwest property boundary. The excavation in the vicinity of well MW-6 was completed to the total depth of approximately 125 feet bgs. The boundaries of the excavation extended beyond the northwestern property boundary toward the abandoned railroad line and encompassed the location of well MW-6. The entire well was removed ("destroyed") on April 14, 2006, in accordance with the SJCEHD and California DWR requirements. Details regarding the well destruction are provided in the "Well Destruction Report for Groundwater Monitoring Well MW-6, Tracy Tire Fire Site, Former Royster Tire Disposal Facility, Tracy, California," prepared by LFR and dated May 24, 2006. 5.6 Excavation of Northern Slope Based on excavation activities that extended to groundwater at the base of the slope (embankment) at the northern extent of the Site (northern edge of BP03) and analytical results of groundwater samples collected from monitoring well MW-6 and soil borings SB-1 and SB-2, it was determined that pyrolytic oil extended northward beneath the embankment. 5.6.1 Slope Stability Evaluations An LFR geotechnical engineer visited the Site on November 23, 2004, to observe the existing slope conditions and the areas proposed for excavation. During the visit, the slope was observed to be approximately 65 feet high with an inclination of approximately 0.7 to 1.5 horizontal to 1 vertical (0.7 to 1.5H:IV). This corresponds to about 36 to 56 degrees from the horizontal. Additionally, the Site was inspected on November 10 and December 15, 2005, by Mr. Jeff Raines, P.E. (C 51120), an LFR civil engineer experienced in geotechnical engineering. Mr. Raines was escorted by Mr. Jim Hasal of SCI on his December 15, 2005 visit. In response to a request from the CIWMB, LFR prepared a geotechnical evaluation letter report entitled, "Evaluation and Recommendations Concerning Cut Slope Stability, Tracy Tire Fire Site, Tracy, California," and dated January 9, 2006. The objective of the letter report was to provide recommendations regarding slope stability and work practices during subsequent excavations at the Site to protect workers. rpt-RA_summ-Nov06-final-0%25 Page 29