ARCHIVED REPORTS_MONITORING WELL INSTALLATION AND BIOSPARGE EVALUATION REPORT

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' depth extent is uncertain. Fill material encountered on the west side of the Site, near the former USTs, consisted of large pieces of concrete and construction debris. Similar fill material was encountered in soil borings drilled inside the building. 1 Soil encountered beneath the fill consisted of silt or clay to the full depth of exploration, 130 feet bgs. Layers of saturated silt, silty sand, sand and gravelly sand of various thicknesses were encountered at most soil boring locations around the site. These saturated soils have been depicted on the cross sections as laterally continuous layers of soil separated by silts and clays. The silts and clays have been described on boring logs as medium to high plasticity. An estimate of intrinsic permeability of the silt and clay is 10-15 to 10-10 cm2 (Fetter, 1994). ' Based on impact observed in each of the saturated zones there appears to be an obvious hydraulic connection and the silt and clay do not appear to be confining layers. ' A 2 to 5 foot thick silt layer with varying amounts of sand is encountered at depths ranging from 15 to 30 feet at most locations drilled around the Site. This silt layer with sand is saturated in some locations and has been described in previous reports as a perched groundwater table. Depending on the exploration method, soil sampling and analysis were not always conducted in this layer. Therefore, the lateral continuity across the site is uncertain. An estimate of intrinsic permeability of this layer is 10-12 to 10-9 cm2. Hydraulic conductivity is estimated at 10'6 to 10-3 cm/sec (Fetter, 1994). PSC has designated this layer as the "shallow" permeable zone. The Chevron site refers to the permeable saturated soil at this depth interval as the "A" zone. This layer is referred to as the shallow layer in previous ' investigations on Site. Sandy and silty sand layers were encountered at depths of approximately 40 to 50 feet bgs in most locations drilled around the Site. These saturated soils ranged from 2 to 15 feet thick and sometimes appear as a continuous silty sand layer or as sandy layers in clay and silt. An estimate of intrinsic permeability of this layer is 10-11 to 10-9 cm2. Hydraulic conductivity is estimated at 10-6 to 10-3cm/sec (Fetter, 1994). The higher permeability and hydraulic ' conductivity values apply to the thinner sandy layers interbedded with silts and clays. This layer has been referred to as the "A" permeable zone in previous reports for the Site. A permeable layer at this depth interval is also encountered beneath the surrounding sites. The former Texaco and ARCO sites have also referred to this layer as the"A" Zone. The Chevron site has referred to this layer as the `B" Zone. A layer described as silty sand, sand and/or gravelly sand was encountered at approximately 65 to 80 feet bgs at most locations drilled around the Site. The layer ranged from 10 feet to over 20 feet thick. At some locations, separation of the sandy material at this depth interval ' and the sandy material encountered above was not well defined. An estimate of intrinsic permeability of this layer is 10-11 to 10-7 cm2. Hydraulic conductivity is estimated at 10-5 to 10-]cm/sec (Fetter, 1994). The higher permeability and hydraulic conductivity values would apply to layers described as gravelly sands. Based on geologic cross-sections prepared by consultants for the Dolly Madison, former Texaco, Chevron, and former Arco sites, a sand and sandy gravel is also present at depths ranging from approximately 60 to 90 feet bgs (Stratus, 2007a; BBL, 2006; Delta, 2000). Previous reports for the site and reports prepared for the former ARCO and Texaco sites have referred to this sandy interval to as the `B" zone. Wells screened in this interval at the Chevron site have been designated"C" Zone wells. Monitoring Well Installation and BioSpurge Evaluation Report Prepared For:Sate Ire Bakery Group,Inc. 5 Prepared By:PSC Industrial Outsourcing,LP Sara Lee—Lincoln Str«t 200912_03-MW Installation&BioSparge Evaluation Report(Fna).doc Report Date:December 3,2009