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a PHASE I HYDROGEOI.OGIC INVESTIGATION 4491 wed Duriam Ferry Road,Tracy,California Delta Projea No.40.91-732 Page 4 w 2 N19nitoring WC11 I 12 ion and DeveloVment Two 2-inch-diameter monitoring wells BMW-2 and MW-3)were installed at the site,and their locations are shown in Figure 2. The wells were constructed with Schedule 40 PVC riserP�Pes ,0.020 slot-size screen, No. 3 Monterey sand filter pack, and sealed with bentonite and cement grout. CorWmcdon details are presented in Appendix C. Monitoring wells MW-2 and MW-3 were screened from 10 feet below the ground surface to their completed well depths of 25 feet. All wells, including monitoring well MW-1, were developed after installation by removing approximately 10 well casing volumes of water to remove any fine-grained sediment. Su ry f +tont rin W Elevations On August 28,1991,Delta personnel surveyed the horizontal location and the elevations of the top of at each monitoring well casing and the adjacent ground surface in reference to.a temporary bench mark. The bench mark was a utility cover located in the center of Durham Ferry Road with an assumed elevation of 100 feet. — 3-4 Ground Wg gr Measurements W Ground water was encountered at approximately 10 feet below the ground surface during drilling. Depths to ground water were measured and recorded for each monitoring well on September 4, 1991, and October 13 and 20, 1991. All field measurements are presented in Table I. The direction of ground water flow on Septeneh:.:4, 1991, was calculated to be flowing toward the southeast. The direction of ground i.. water flow on October 13 and 20, 1991,was calculated to be flowing toward the east-northeast at a gradient of approximately 0.005 foot per foot. A ground water table contour map was generated using the water i-a level measurements collected on October 13, 1991, and is presented in Figure 3. ~ P14100L9P ftf