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A-2 <br /> 1.4 Soil Classification <br /> As the samples were obtained in the field, they were classified by the Delta field geologist in accordance <br /> ' with the Unified Soil Classification System as outlined in ASTM D2488-84 Logs of the borings <br /> indicating the depth and identification of the various strata, the blow counts, water-level information and <br /> ' pertinent information regarding the method of maintaining and advancing the bore hole were completed <br /> The boring logs are included in Appendix B <br /> ' <br /> 1.5 Soil-Sample Screening/hNu Photoionization Detector Method <br /> 1 After soil-sample jars were brought to ambient temperature, the head-space vapor of the soil-sample jars <br /> were screened with an hNu photoionization detector equipped with a 10 2 eV lamp (calibrated to benzene <br /> with isobutylene)for direct reading in parts per million (ppm) The hNu probe was inserted through the <br /> ' aluminum foil and into the head space of the jar The highest observed reading was recorded on the <br /> ' boring logs <br /> 1.6 Monitoring Well Construction <br /> Each monitoring well was completed using four-inch-diameter, flush-threaded, Schedule 40 PVC, <br /> 0 010-inch slotted well screen and blank casing The bottom of the casing was sealed with a solid PVC <br /> ' cap, and the top was covered with a locking plug-type cap <br /> ' The annular space between the borehole wall and well casing was backfilled with clean filter sand (2112) <br /> from the bottom of the borehole to approximately 3 5 feet above the slotted interval A 2-foot-thick <br /> ' bentonite seal was placed above the gravel pack and the remainder of the annulus was filled with a cement <br /> grout to a point just below the well head. For specific details refer to Appendix D <br /> The well head is contained below surface grade in a watertight traffic rated locking box which extends <br /> ' slightly above the surrounding grade so that surface run-off is directed away from the well head Details <br /> of monitoring well construction are presented on the boring Iogs in Appendix B of this report. <br /> 1.7 Monitoring Well Development <br /> ' Each monitoring well was developed after construction by bailing with a new, dedicated, disposable <br /> plastic bailer until the ground water removed was relatively sediment free, until measurements of pH, <br /> ' RPT 112!DM <br />