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May 5, 2000 Ramage Environmental Stefono's Gas Site Stockton, CA The CPT holes were grouted using our support rig The grouting procedure consists of using a retraction grout collar which permits grouting of the holes as the CPT and sampling rods are retracted 3 0 CONE PENETRATION TEST DATA & INTERPRETATION The cone penetration test data is presented in graphical form in the attached Appendix Penetration depths are referenced to existing ground surface This data includes CPT logs of measured soil parameters and a computer tabulation of interpreted soil types along with additional geotechnical parameters and pore pressure dissipation data The stratigraphic interpretation is based on relationships between cone bearing (Qc), sleeve friction (Fs), and penetration pore pressure (Ut) The friction ratio (Rf), which is sleeve friction divided by cone bearing, is a calculated parameter that is used to infer soil 4P behavior type Generally, cohesive soils (clays) have high friction ratios, low cone bearing and generate large excess pore water pressures Cohesionless soils (sands) have lower friction ratios, high cone bearing and generate little in the way of excess pore water pressures The interpretation of soils encountered on this project was carried out using recent correlations developed by Robertson et al, 1990. It should be noted that it is not always possible to clearly identify a soil type based on Qc, Fs and Ut In these situations, experience and judgment and an assessment of the pore pressure dissipation data should be used to infer the soil behavior type The soil classification chart used to interpret soil types based on Qc and Rf is provided in the Appendix We hope the information presented is sufficient for your purposes If you have any questions, please do not hesitate to contact our office at (925) 313-5800 Sincerely, Tim J Boyd Operations Manager— CPT Division i