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The CH21VI HILL borings were 4-7/8-inch diameter and extended to depths ranging from 43 to 102 feet. The borings were advanced using mud rotary drilling methods with a truck-mounted Failing 750 drill rig. As each boring was completed, the hole was grouted to the surface using a "neat" cement grout. The borings were grouted from the bottom upward using a 2-inch drill pipe as a tremie. Relatively undisturbed samples were obtained using a 3-inch outside diameter Shelby tube sampler (ST samples) or Pitcher Barrel sampler (PB samples). The Pitcher Barrel sampler was used to obtain samples of very stiff clay where the Shelby tubes could not be pushed. This sampling was performed in general accordance with procedures for Thin-Walled Tube Sampling of Soils as described by the American Society of Testing and Materials (ASTM), Standard D 1587. Disturbed soil samples were obtained from the borings using a 2- inch outside diameter split-spoon sampler, driven as described for the Standard Penetration Test(SPT), ASTM Standard D1586. Soil recovered during the drilling program was visually classified by a CH2M HILL engineer in general accordance with ASTM D2487 and D2488. The soil names on the boring logs reflect these ASTM standards. Pocket penetrometer tests were conducted on most cohesive samples. Samples were then prepared for storage by placing representative portions in plastic bags or by sealing the sampling tube with plastic cap and tape. Sample descriptions, blow counts recorded during the SPT, and other relevant information were recorded on the soil boring logs. Selected soil samples obtained by CH2M HILL from its subsurface investigation were tested in the laboratory by Harding Lawson Associates (HLA) of Concord, California. Index tests performed by HLA included determining the liquid limit, plastic limit, and moisture content of the selected samples. Engineering property tests performed included Unconsolidated Undrained (UU) triaxial compression and consolidation tests. Detailed results of the tests performed are included in the Stability and Settlement Analysis of that report. The soil encountered during the CH2M HILL field investigation generally consists of interbedded layers of sand, silt, and lean clay. The cohesive materials are generally of very stiff to hard consistency. The cohesionless materials can be characterized as dense to very dense. The soil deposits at the site were found to be heterogeneous and laterally and vertically discontinuous. Based on the four soil borings performed for this geotechnical exploration, the subsurface soils at the site can be divided into six general layers of interest. It should be noted that the generalized subsurface profile described below has been greatly simplified for the purpose of this report. Beginning at the existing ground surface (approximately elevation 39 feet MSL), these six layers are as follows: • A 10-to 15-foot layer of light brown material ranging from lean clay to silt and silty clay. This layer is dry and very stiff to hard in consistency, with moisture contents typically at or below the plastic limit. A UU triaxial compression test performed on a sample at a depth of 15 feet in Boring BH-4 indicated an undrained shear strength of 5,145 pounds per square foot (psf). SPT blow-counts in this layer are typically greater than 50. • A 16- to 20-foot layer of material ranging from silty sand to clayey sand. This layer is dry to moist and typically dense to very dense. Within this layer, a 5-foot Forward Composting Facility RCSI 7/20/09;Page 21 SWT Engineering