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Soil type and properties of the materials encountered in the geotechnical investigations performed by EMCON and InsituTech were generally consistent with the conditions deter- mined by C112M HILL described above. In EMCON's subsurface investigation, a Modi- fied California Sampler (with a 140-pound hammer with a 30-inch drop) was used to col- lect samples. Blow counts recorded with the Modified California Sampler typically ranged from 20 to 60 blows per foot. Unconfined compression tests were performed on silty clay samples between depths of 3 and 10 feet. The compressive strengths ranged from 1,310 psf to 5,100 psf for an average of approximately 3,000 psf (Note: the undrained 1 shear strength is defined as one half of the unconfined compressive strength) (EMCON, 1972). Shear strengths based on InsituTech's CPT data (performed to a maximum depth of 50 feet) typically ranged from approximately 4,000 psf to over 10,000 psf. Based on these CPT logs, a lower bound shear strength value of 2,000 psf was used in InsituTech's stabil- ity evaluation for WMU E (InsituTech, 1987). Table 2.2 summarizes the results of the subsurface soil investigations for the six generalized zones mentioned above. Table 2.2 Summary of Subsurface Soil Properties and Unit Weights Friction Unit Angle Cohesion Weight Material (deg) (Psf) (per Foundation Materials (simplified profile): ® Elevation 10 to 39 feet, dense silty sand and very stiff lean clay 33 0 120 • Elevation zero to 10 feet, very stiff lean clay 0 2,300 120 • Elevation zero to -30 feet, very dense silty/clayey sand 36 0 120 • Elevation -30 feet to -60 feet, very stiff lean clay 0 3,300 125 • Elevation -60 feet to -150 feet, very dense silty/clayey sand 36 0 125 • Elevation -150 feet to -200-feet, very dense poorly graded sand 40 0 125 B. Monitoring Describe plans for leachate monitoring. At least one sample of leachate from each of the first five composting batches of feedstock generating leachate must be collected and ana- lyzed for organic phosphates, using EPA method 8140, and nitrates. [Note: The new regulations do not appear to require leachate monitoring.] LDescribe plans for ensuring that all end-products, excluding noncompostable waste, have met the following environmental health standards for: (1) Maximum acceptable metal concentration, and (2) Pathogen reduction. wa10029B".p'P 5/42 9/28/94 42