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Ms Margaret Lagroto August 11,2004 Subsurface Assessment Report Project No 2033-15600-01 Joe's Truck Plaza, 15600 South Harlan Road,Lathrop,CA Page 3 • Advanced borings adjacent to each CPT boring to collect soil and HydropunchTm groundwater samples from select intervals • Advanced one on-site soil boring to approximately 19 feet bgs using 10-inch diameter hollow stem augers The boring was converted to a 4-inch diameter groundwater monitoring well (MW-7) • Collected soil samples from boring MW-7 for lithologic description, field screening, and possible laboratory analysis • Developed and sampled the newly installed wells • Surveyed the elevation and horizontal coordinates of the newly installed monitoring well and each CPT boring Prior to implementation of field activities, Stratus secured an access agreement for the Storage Pro facility (north of the Joe's Truck Plaza facility at 15550 South Harlan Road), and an encroachment permit (No 261) from the City of Lathrop Permits to advance the soil borings and construct the well were obtained from SJCEHD (SR# 37889 through . 37892) Drilling locations were marked in white paint as required by law, and Underground Service Alert, SJCEHD, Storage Pro, and the City of Lathrop were notified of the work schedule Standard field practices and procedures for all fieldwork are described in Appendix A All work was conducted under the direct supervision of Stephen J Carter, a State of California Registered Geologist (RG 5577) Field Activities CPT Testing A Stratus geologist was on-site to oversee Gregg In Situ, Inc (C-57 #656407) of Martinez, California, complete the CPT testing and direct push sampling on May 10 through 14, 2004 The initial 5 to 10 feet of each CPT boring was hand-cleared to avoid damage to subsurface utilities The CPT method consists of advancing a cone-tipped cylindrical probe (1 7 inches in diameter) into the ground while simultaneously measuring the resistance to penetration The CPT method estimates soil lithology by comparing the force (cone bearing pressure) required to advance the probe (qt) to the friction ratio (R f) [Rf is a parameter defined as the sleeve friction (fs) divided by the probe tip load (qt)times 100] and the pore water pressure (u2) A graphical diagram illustrating CPT interpretations of soil types is included in Appendix B Computer generated CPT logs were plotted in the field to provide a graphical log of subsurface soil lithology The CPT test data report, which includes logs of all CPT data, graphical geologic logs, and additional information on the CPT technique, is presented in Appendix B CPT tests P 1Joe's Truck PIaza\Reports\CPT report 08-2004 doc