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GEO.V ATROX of induration, calcareous content,presence of fossils and other distinctive materials. The original field logs will be retained by the Geomatrix office for review by the responsible professional and for storage in the project files. 4.0 GEOPHYSICAL LOGS Following completion of drilling, downhole geophysical logs may be performed after the drilling fluid has been circulated to decrease the amount of suspended sediment in the return fluid. Geophysical methods and equipment will be selected to provide stratigraphic or hydrogeologic data appropriate for the project. Geophysical logging will be done as quickly and promptly after drilling as feasible, while the boring sidewall is still in stable condition, to reduce the possibility of bridging. Instruments on the logging unit will be adjusted to try to give the maximum defini- tion of strata boundaries. All downhole geophysical equipment will be cleaned before and after use in each borehole. 5.0 FIELD SCREENING Soil samples collected from the borings may be screened using a portable meter such as a photoionization detector(PID), a flame ionization detector(FID), a lower explosion limit (LEL) meter or other organic vapor meter. The meter may be used to assess the presence of volatile organic compounds (VOCs) or other gases in soil samples. Additional field screening techniques for chemical characterization of soils may include x-ray fluorescence(XRF) and thin-layer chromatography (TLC). Procedures for field screening are described in the protocol SOIL SAMPLING FOR CHEMICAL ANALYSIS. 6.0 DESTROYING SOIL BORINGS Soil borings that are not completed as monitoring wells will be destroyed by filling the holes with a neat cement grout, cement/sand grout, or cement/bentonite grout. A high-solids bentonite DRILLING AND DESTRUCTION OF SOIL.BORINGS Page 5 of 6- PROTO-DD.doe REVISION D'AM MARCH 1996 DD-5