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ilk" KLEINFELDER <br /> according to the Unified Soil Classification System (USCS), and collected soil samples <br /> Boring logs and a USCS legend are included in Appendix B. <br /> Soil encountered in the vertical borings drilled at the ends of tank T1 was predominantly <br /> ' well sorted fine grained sand and silty sand from the ground surface to approximately 20 <br /> feet, grading to mostly silt from 20 feet to the total depth of each boring (25 feet). <br /> Soil encountered in the angle borings under T2 and 13 was generally silty fine grained sand <br /> g g <br /> to well sorted fine grained sand with occasional 0 5 to 1 foot thick interbeds of silt from the <br /> ground surface to the total depth of each boring (equivalent vertical depth of <br /> approximately 18 feet) <br /> 3 3 SOIL SAMPLING <br /> Soil samples were collected at 5 foot intervals for field screenin litholo is 'logging, and <br /> P g� g <br /> possible laboratory analysts Samples were collected by drilling the boring to a point <br /> immediately above the desired sampling depth and then driving (vertical borings) or <br /> pushing (angle borings) a Modified California Sampler, lined with three brass tubes, into <br /> the undisturbed soil The sampler was then removed from the bottom of the boring and <br /> the brass tube retained for possible laboratory analysis was immediately sealed with Teflon <br /> tape and plastic caps It was then labeled, logged on a chain-of-custody, and placed in an <br /> iced cooler for transport to the analytical laboratory The remaining two tubes were used <br /> for lithologic logging and field vapor screening <br /> 3 4 FIELD ORGANIC VAPOR SCREENING <br /> An organic vapor detector (Photovac TIP), using a photoionization detector (PID) was <br /> used to provide a qualitative screening of each soil sample collected from the borings The <br /> PID measures ionizable compounds (with excitation potentials less than 10 6 eV) in the air <br /> 1 in parts per million by volume (ppmv) Field calibration was performed using 101 ppm <br /> isobutylene span gas Ambient air was used to set the instrument to zero The soil <br /> contained in the cone of the sampler or in a brass tube was exposed and screened with the <br /> organic vapor detector immediately after the drive sampler was opened. The vapor <br /> reading was noted as the field screening result on the boring log (see Appendix B for logs). <br /> FR25-91-29 <br /> Page 5 of 11 <br /> Cop,,,,ht 1991 Kle,nfelder,Inc <br />