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October 17, 2000 Aqua Science <br /> Singh Site <br /> Tracy, CA <br /> 3 0 CONE PENETRATION TEST DATA & INTERPRETATION <br /> The cone penetration test data is presented in graphical form in the attached Appendix <br /> Penetration depths are referenced to existing ground surface This data includes CPT <br /> logs of measured soil parameters and a computer tabulation of interpreted soil types along <br /> with additional geotechnical parameters and pore pressure dissipation data <br /> The stratigraphic interpretation is based on relationships between cone bearing (Qc), <br /> sleeve friction (Fs), and penetration pore pressure (Ut) The friction ratio (Rf), which is <br /> sleeve friction divided by cone bearing, is a calculated parameter that is used to infer soil <br /> behavior type Generally, cohesive soils (clays) have high friction ratios, low cone bearing <br /> and generate large excess pore water pressures Cohesionless soils (sands) have lower <br /> friction ratios, high cone bearing and generate little in the way of excess pore water <br /> pressures <br /> The interpretation of soils encountered on this project was carried out using recent <br /> correlations developed by Robertson et al, 1990 It should be noted that it is not always <br /> possible to clearly identify a soil type based on Qc, Fs and Ut In these situations, <br /> • experience and judgment and an assessment of the pore pressure dissipation data should <br /> be used to infer the soil behavior type The soil classification chart used to interpret soil <br /> types based on Qc and Rf is provided in the Appendix <br /> We hope the information presented is sufficient for your purposes If you have any <br /> questions, please do not hesitate to contact our office at (925) 313-5800 <br /> Sincerely, <br /> f <br /> Tim oyd <br /> Operations Manager — CPT Division <br />