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3-6 On the behalf of Sheldon, BC prepared a work plan addendum, dated July 9, 1993, to continue the excavation of affected soil. This work plan addendum was submitted to the County �- and verbally approved by the County on July 10, 1993, and in a letter dated August 4, 1993. The BC work plan addendum and County approval letter are included as Attachment D_ The additional excavation and stockpiling of hydrocarbon affected soil was resumed on July 19, 1993. As authorized by Sheldon, a BC geologist was present on-site to observe the excavation. A representative of J_H. Kleinfelder and Associates (Kleinfelder) was also present on-site to provide geotechnical expertise for the excavation process. Correspondence from Kleinfelder regarding the excavation work is provided in Attachment E. Soil was excavated based on visual identification of affected soil. The sidewalls and bottom of the excavation were occasionally sampled by BC and analyzed for BTEX, TPHg, TPHd, and TPHmo by WEST on a 24-hour rush basis to evaluate whether affected soil had been removed. Soil samples were collected under the supervision of a representative from the County. The location and depth of soil samples collected throughout the excavation are shown on Figure 3-2 and analytical results of the samples are summarized in Table 3-3. Excavation was terminated on August 6, 1993. The final size of the excavation averaged 65 feet wide by 100 feet long and ranged in depth from 20 to 44 feet below ground surface (Figure 3-2). A total of approximately 12,000 cubic yards of soil were excavated. w The size of the excavation was limited by physical and safety constraints. Therefore, some petroleum hydrocarbon affected soil was left in place in the western half of the excavation L underneath the ramp used by the excavator. Factors limiting the physical size of the excavation included the property line to the south, existing structures to the east and north, and limited working space and the two 2-inch gas pipelines to the west, where excavated soil was being �. stockpiled. As described in our September 3, 1993, Status Report to the County (Attachment F), the soil was shown not to exhibit the characteristics of a hazardous waste as defined in Title 22, Article 3, Chapter 11 of the California Code of Regulations. Specifically, the soil was shown 5 to be non-toxic, non-reactive, non-corrosive, and non-ignitable. The analytical reports +� documenting the toxicity, reactivity, corrosivity, and ignitability of the soil are included in Attachment F. Additionally, the hydrocarbons were shown to be non-leachable, based on TCLP analyses of soil samples. Based on the non-leachable and non-hazardous (Title 22, Article 3, Chapter 11) nature of the soil, BC recommended backfilling the excavation with the stockpiled material and L returning the site to its original (pre-excavation) condition. BC also recommended collecting Use or disclosure of data contained on this sheet is subject to the restriction specified at the beginning of this doctunent. 1; R3\L\760MFF0R'iS�I LLT-0IL.0 L0 QMS-PS2200 4 Yr