Laserfiche WebLink
Water was injected in the remaining holes starting at various depths ranging from 120 to 660 feet below <br />ground surface. The holes to the west in Utah were generally dryer and required less injection of water <br />starting at greater depths. Addition of bentonite was not required in any of the holes. <br />Because of the need to inject water, it was not possible to determuie ground water inflow rates except for <br />Hole WW-07-9. This hole was drilled dry to its total depth of 660 feet. When it was probed two hours <br />later, it had 56 feet of standing water. The hole had a diameter of 6 inches, which equated to a cumulative <br />inflow rater of 0.7gallons per minute over 660 feet of drill hole and 4 potential water-bearing zones. Based <br />on the 5 dry holes and the other drill holes where water was only injected near the bottom of the hole to <br />clean the holes out, it did not appear that the upper Salt Wash formation (ore zone) was producing water. <br />The water that flows from the hole during drilling is almost entirely injected water, so it is impossible to <br />sample and analyze ground water from discrete water bearing intervals during exploration drilling. <br />However, the location of perched water tables can be estimated based on cuttings, electric logs of the <br />hole, and the depth at which the driller has to start injecting water. The attached well logs indicate where <br />the driller started injecting water and the water level in the hole when it was later probed. These standing <br />water levels should not be interpreted as static water levels because the ground water may not have fully <br />equilibrated when the probing was performed. <br />The drill logs for the four holes used to develop cross section A-A' in Figure 2 provide the following <br />information: <br />Hole WW-07-12: Driller started injecting water at 420 feet; water level when probed = 394 feet; Brushy <br />Basin sandstone Qmb ss) interval was 395-435 feet. <br />Hole WW-07-13: Driller started injecting water at 400 feet; water level when probed = 385 feet; Brushy <br />Basin sandstone Qmb ss) interval was 380 to 418 feet. <br />Hole WW-07-11: Driller started injecting water at 150 feet (base of Burro Canyon); water level when <br />probed = 618 feet; Brushy Basin sandstone Qmb ss) interval was 383 to 421 feet. <br />Hole WW-07-10: Driller started injecting water at 400 feet; water level when probed = 397 feet; Brushy <br />Basin sandstone Qmb ss) interval was at 388 to 416 feet. <br />In the case of Holes 10, 12, and 13, the top 12 to 25 feet of the Brushy Basin sandstone interval was not <br />wet enough to require water injection for drill cutting removal. The same is true in the decline where the <br />two thin stringers above the water producing zone are both dry. The water levels when probed were never <br />found to be above the sandstone interval. If the ground water were confined, it would rise up the hole to a <br />point above the top of the sandstone interval. <br />Conclusion <br />The drilling information indicates that the ground water encountered in the Brushy Basin is unconfined, <br />perched, and limited in extent. Based on the information presented above, I believe the lower Brushy <br />Basin water-bearing zone encountered in the decline is lenticular and probably does not extend over a <br />wide area. I do not believe that the ground water could ever rise significantly above its entrance point in <br />the decline. For this reason, I believe that a design head fox the seal need not be more than 15 vertical feet <br />above the water entrance point into the decline. <br />3 <br />