Introduction Drill ing operations Lithologic sampling and well logging Lithology Hydrologic properties of sidewall core samples Geophysical well logs Hydrologic testing and water sampling Drill ing fluid Water levels Pumping tests Radioactive-tracer borehole flow and temperature survey Injection tests Chemical analysis of watei Selected references ILLUSTRATIONS Page Figure 1. Map showing location of test well USW H-4 and nearby geographic features in southern Nevada 2 2. Chart showing generalized vertical distribution of out-ofgage hole 13 3-26. Graphs showing: 3. Drilling-fluid use 20 4. Water-level drawdown versus time for pumping test 2, depth interval from 519 to 1,219 meters-23 5. Water-level drawdown versus time for pumping test 3, depth interval from 519 to 1,219 meters 23 6. Water-level recovery versus time for pumping test 2, depth interval from 519 to 1,219 meters 24 7. Water-level recovery versus time for pumping test 3, depth interval from 519 to 1,219 meters 24 8. Semi logarithmic graph of water-level drawdown versus time for pumping test 6, depth interval from 519 to 1,219 meters-25 9. Logarithmic graph of water-level drawdown versus time for pumping test 6, depth interval from 519 to 1,219 meters 25 10. Water-level recovery versus time for pumping test 6, depth interval from 519 to 1,219 meters 26 11. Borehole-flow and temperature survey for test well USW H-4 showing percent of pumping rate produced for intervals from 555 to 1,219 meters GEOHYDROLOGIC AND DRILL-HOLE DATA FOR TEST WELL USW H-4,

This report presents the results of hydraulic testing of rocks penetrated by USW H-4, one of several test wells drilled in the southwestern part of the Nevada Test Site, in cooperation with the U.S. Department of Energy, for investigations related to the isolation of high-level radioactive wastes in volcanic tuffs of Tertiary age. All rocks penetrated by the test well to its total depth of 1,219 meters were volcanic. Static water level was at a depth of 519 meters below land surface. Hydraulic-head measurements made at successively lower depths during drilling in this test hole indicate no noticeable head change. A radioactive-tracer, borehole-flow survey indicated that the two most productive zones in this borehole occurred in the upper part of the Bullfrog Member, depth interval from 721 to 731.5 meters, and in the underlying upper part of the Tram Member, depth interval from 864 to 920 meters, both in the Crater Flat Tuff. Hydraulic coefficients calculated from pumping-test data indicate that transmissivity ranged from 200 to 790 meters squared per day. The hydraulic conductivity ranged from 0.29 to 1.1 meters per day. Chemical analysis of water pumped from the saturated part of the borehole (composite sample) indicates that the water is typical of water produced from tuffaceous rocks in"southern Nevada. The water is predominantly a sodium bicarbonate type with small concentrations of calcium, magnesium, and sulfate. The apparent age of this composite water sample was determined by a carbon-14 date to be 17,200 years before present.