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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 Appendix II of the Stability and Settlement Analysis in Appendix G. The soil encountered during the CH2M HILL field investigation generally consists of inter- bedded 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 heterogenous and laterally and ver- tically discontinuous. Based on the four soil borings performed for this geotechnical ex- ploration, 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 (approx- imately 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 zone of very stiff lean clay (UU shear strength of 2,262 psf) was encoun- tered in Boring BH-2 at an approximate depth of 19 feet. This layer was not encountered in other borings and is believed to be discontinuous. • A 5- to 10-foot layer of very stiff yellowish-brown lean clay. This material is moist, with moisture contents between the plastic and liquid limit. A consoli- dation test indicates that this material is consolidated to approximately three times the effective overburden stress overconsolidation ratio (OCR) of 3. The OCR is the ratio of the maximum effective stress the soil has been subjected to in the past (preconsolidation pressure) to the existing effective stress in the soil. A UU triaxial compression test at an approximate depth of 34 feet in Boring BH-1 indicated a shear strength of 2,286 psf. • A 30-foot layer of material consisting of very stiff to hard silt and lean clay. This material is moist to wet, with moisture contents between the plastic and liquid limit. This material has an approximate OCR of 1.7 (Boring BH-1, approximate depth of 78 feet). • Very dense poorly graded sand was observed near the bottom of Boring BH-1, starting at an approximate depth of 100 feet. Sand was also observed in EMCON's Boring 17 to 178 feet, the maximum depth drilled (EMCON, 1972). =10029M4.wp5/41 9128/% 41