1 Cut-and-Cover Conduit --Typical Sequence of operation 77 Figure 1 LIST OF FIGURES Title Map of the Columbia Basin project lands showing the location of the 5 Photograph illustrating the characteristic trench-like shape of the Upper Page 3 5 7 8 12 6 Photograph of the Grand Coulee Dam area looking southwest into the 13 7 View of the basalt flows on the east wall of the Grand Coulee 16 8 A closeup aerial view of the Feeder canal slide area 23 21 9 Surface geologic map of a portion of the Feeder canal cut-and-cover 22 10 11 Generalized geologic section along the center line of North Dam 24 25 12 Tractor-drawn cultivators used to clear areas in the Equalizing reser- 28 13 Airplanes used to spray 2-4-D solution on grass and brush on the coulee 28 14 Wheel-tractors equipped with power mowers used to cut brush in open 29 areas 15 Pneumatic limb loppers used to cut brush in inaccessible areas Preliminary cost comparisons for the Feeder canal cut-and-cover de- 30 34 36 37 20 Design studies for the Feeder canal cut-and-cover conduit 38 21 General plan and sections of the Feeder canal cut-and-cover conduit 40 22 Chart showing interrelationship between pumping cost and conduit cost Details of 24- by 25-foot radial gates for the Feeder canal check struc- 44 26 Plan and sections of the Feeder canal chute structure before modifi- 45 |