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1 <br /> 1 <br /> APPENDIX B <br /> FIELD ACTIVITIES AND PROCEDURES <br /> ' Monitoring Well Installation <br /> Three shallow monitoring wells (approximately 17 feet deep) were <br /> installed on September 9, 1991 . Wells were installed under San <br /> Joaquin County Public Health Services Environmental Health Division <br /> permit number 91-1770. <br /> ' Drilling was completed using the hollow-stem auger drilling method <br /> and was performed by Spectrum Exploration Inc. , of Stockton, <br /> ' California. All field activities during drilling, logging of soil <br /> lithology, well installation, well development, and sampling were <br /> performed under the supervision of a Registered Geologist. <br /> Borings were drilled to depths of 17 feet below surface grade. <br /> Soil sampling was conducted near-continuously during drilling of <br /> the well borings for lithologic description and possible chemical <br /> analysis using a 2-inch diameter "Modified California" drive <br /> sampler inserted with brass liners. Graphic illustrations and <br /> lithologic descriptions of the sediments encountered in the <br /> ' borings, and the depths of samples retained for chemical analysis, <br /> are indicated on the field boring logs contained in Appendix A. <br /> The well bores were completed as groundwater monitoring wells by <br /> installing threaded-]oint, 2-inch diameter schedule-40 PVC blank <br /> casing and 0.02 factory slot screens. Well screens were positioned <br /> to intersect the static water table to a maximum depth of five feet <br /> ' or until a change in lithology was encountered. The well annulus <br /> surrounding the perforated interval in each well was sand packed <br /> with Lapis Luster #1c sand to a level approximately two feet above <br /> ' the top of the perforated screen. A one foot bentonite pellet seal <br /> was placed above the sand pack to prevent infiltration of the grout <br /> seal . The remaining annular space above the bentonite seal was <br /> grouted with a cement-bentonite mixture. A locking cover was <br /> ' placed over the top of the casing to protect the integrity of the <br /> well . <br /> ' All well drilling equipment was steam-cleaned prior to drilling and <br /> well installation. <br /> ' Soil Sampling <br /> B1 <br /> 1 <br />