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Gealogi ca l 1'eckxics lxc. Soil&Groundwater Investigation Report Marci Property Page 2 Project No. 701.2 July 24,2002 i.I �., orientation of the new wells will allow the deeper aquifer gradient to be determined and the site conceptual model to be refined. In their letter of November 16, 2001, the SJC PHS/EHD directed that additional water table wells be placed to the northwest of MW-5 and in the location of the former tank excavation. Well MW-7 was placed adjacent to the former UST excavation with the May 8, 2002, verbal concurrence of SJC PHS/EHD's Sam Savig. Well MW-8 was placed approximately -. 80 feet northwest of MW-5. 2.1 Soil Boring Installation SJC PHS/EHD was notified 48 hours prior to commencing work. The subsurface was cleared of underground utilities by notifying Underground Service Alert. The soil borings were drilled to a depth of 70 - 95 feet bgs using an 8-inch outside diameter, continuous ►� flight, hollow stem auger owned and operated by V&W Drilling (C57## 720904). Soil cuttings were placed on plastic at the site until their disposal can be arranged. Water from drilling decontamination and borehole purging was placed into DOT approved 55 gallon drums for on site storage. 2.1.1 Sampling Procedure Soil samples were collected for geological and analytical evaluation at 5-foot intervals in borings MW-7, MW-8 & MW-104. Boring MW-106 was free drilled to 75 feet bgs due to its proximity to well MW-6. Soil samples were collected for geological and analytical evaluation at 5-foot intervals starting at 75 feet bgs to the terminal depth. Boring logs providing sediment description using the Uniform Soil Classification System (USCS) and field observations were completed by GTI geologists working under the supervision of Ray Kablanow, a registered geologist. Soil samples were collected in 6.0 inch brass liners using a 2.0 inch modified California split spoon sampler. All soil samples were sealed with Teflon sheets, capped with plastic end caps, labeled and placed into a cooler at 4° Celsius for transport to the laboratory following Chain of Custody protocol. Because every soil sample collected was not submitted for laboratory analysis, a field observation screening process was used to gather information on the subsurface soils and geologic units. The screening method that was used provided information to reduce the number of samples tested at the laboratory. The following information was noted: • Sediment type, including: grain size, clay content and color • Moisture content • Visible evidence of contamination, i.e., color change due to reduction of iron or discoloration from hydrocarbons and other pollutants • Although it was planned to use an OVM to screen the soil samples, the unit malfunctioned and was not used. .. Details on the geology encountered during the completion of the boreholes as well as the field observations of contamination are included in Section 4.1, Geology and Field Observations. V