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Report—Pit Closure Page 4 612 N.Buena Vista Ave. t Project No. 480.2 September 26, 2007 labeled and placed in a cooler chilled to 4 degrees C. for transport to a State ' certified laboratory under Chain-of-Custody protocol. 2.3 Pit Excavation ' The brine pit was concrete lined with horizontal dimensions of about 12 by 15 feet, and about 7 feet deep. Del-Tech Geotechnical Services mobilized to the site, ' and on June 27, 2007 removed the concrete bottom of the pit with the use of a concrete breaker mounted on a backhoe.' The concrete bottom proved to be 12 inches thick, and steel reinforced. Upon removal of the concrete pit bottom, the native soil beneath the bottom was excavated an additional 4 to 5 feet using a Case 580K backhoe. The excavation extended to a maximum depth of about 12 feet below grade, and a total of about 25 cubic yards of salt-impacted soil was removed and stockpiled on the site pending profiling and removal. After the pit excavation was completed, groundwater gradually filled to a depth of about 11 feet. On June 29, 2007, a vacuum truck owned and operated by American Valley Waste Oil, a company licensed to handle oil waste, removed the groundwater contained in the pit. The water was pumped directly from the pit into the vacuum truck for recycling. Pumping continued until the pit was dry, and approximately 850 gallons of salt-impacted groundwater was removed in ' this way. Documentation pertaining to the disposal of this material is included in Appendix D. 2.4 Confirmation Soil Sampling During the completion of the pit excavation, a series of three soil samples was collected at increasing depths. Samples were collected from 1 foot, 3, feet, and ' 5.5 feet below the pit bottom. These depths are reflected in the sample IDs indicated in the table below. A slide-hammer actuated drive sampler fitted with a 2-inch diameter by 6-inch long brass sample sleeve was driven into the sides ' and bottom of the pit. Upon retrieval, the sample sleeves were removed from the sampling tool, sealed with Teflon sheets and secured with plastic end caps. The ' samples were then labeled and placed in a cooler chilled to 4 degrees C for transport to a State certified analytical laboratory under Chain-of-Custody protocol. rThe three confirmation soil samples were submitted for analysis at a California State Certified Laboratory (Argon Labs in Ceres, DHS #2359). The soil samples ' were analyzed for total chlorides by EPA Method 300.0. The following table summarizes the laboratory analytical results. Copies of the laboratory data sheets are attached as Appendix A. 2937 Veneman Ave.,#B240 Geo-Phase Environmental Inc. Phone (209) 569-0293 Modesto, CA 95356 Fax (209) 569-0295 t