Figure 138. --Clear Creek Power Conduit--Pressure tunnel disposal areas. TRACED. UNITED STATES DEPARTMENT OF THE INTERIOR CENTRAL VALLEY PROJECT-CALIFORNIA CLEAR CREEK POWER CONDUIT SUBMITTED. ...M.. RECOMMENDED... Ripper. CHECKED. Pult num DENVER, COLORADO, OCT 31,000 416-0-218 Figure 139.--General view of Clear Creek Tunnel materials disposal area near Crystal Creek adit. View was taken from high on the mountainside directly above the adit. Concrete batching plant is in center of photograph. TD-4108-CV, December 17, 1958. Figure 140. --Clear Creek Power Conduit--Surge tank at station 559+34. 27--Plan and basin. -5" Layer of sond 6" Open joint sewer pipe PIPE DRAIN, TYPICAL #3 Bors Gravel fill 12 3" Layer of sand GRAVEL DRAIN TYPICAL NOTES Concrete design based on a compressive strength of 3000 pounds per square inch Ploce sewer pipe drain on a 0025 slope to lead-off line See 416-D-112 for Surge Tank Sections and REINFORCEMENT PATTERN IN BASIN CHANGED. UNITED STATES DEPARTMENT OF THE INTERIOR CENTRAL VALLEY PROJECT-CALIFORNIA TRINITY RIVER DIVISION CLEAR CREEK POWER CONDUIT-STA. 559+34.27 DRAWN..: TRACED. SURGE TANK PLAN AND BASIN BAM BUBMITTED. ..S.MA. CHECKED RECOMMENDED. DENVER, COLORADO, SEPT. 24, 1954 throttling from riser into the tank was taken as that which would permit the water in the riser to reach the riser top in a period of time greater than 24 where: = length of tunnel, forebay to surge tank (56,000 feet), and a = velocity of pressure wave in tunnel (taken at 4, 300 f. p. s.) Thus, by providing storage space for a considerable quantity of water in the surge basin during upsurge, and by limiting the rate of pressure rise in the tunnel by use of the riser with throttled ports, it was possible to limit the pressure gradient rise for the tunnel to very moderate values. Figure 142 shows time-sequence photographs of the surge tank during actual operating conditions. The storage basin was made with the bottom (elevation 1902. 5) 156 by 156 feet in plan, side slopes of 1-1/2 to 1, and a top elevation of 1930. The invert elevation of the tunnel at the centerline station of the surge tank is 1690. 53, which places the bottom of the tank at elevation 1712. 03 or low enough to contain the downsurge when picking up the second half of the flow (1, 600 second-feet) in 4 seconds. The operating requirement assumed for downsurge determined the elevation of the lower end of the tunnel, which established the tunnel slope of 0.0032. The port throttling for the off-load condition which nearly meets the time requirement 24 for the water to reach the top of the riser is that which requires a differential head of 30 feet to pass a flow of 3,200 second-feet from riser into the tank. For the load-on condition, it was desirable to provide a low coefficient of discharge for flow from tank to riser through the ports. This was achieved to some extent by providing a reentrant corner on the tank side of the ports. Model studies were conducted to establish discharge coefficients for flows either into or out of the tank through the riser ports. Results of these studies are presented in appendix H, which also describes studies made to establish overflow conditions at the top of the riser. (b) Structural Design--Surge Basin. --Surface topography and geological data along the proposed tunnel alinement were studied with regard to economical construction of the surge basin. From these data the location of the basin was then chosen. The surge tank was located directly below the center point of the basin and the final alinement of the tunnel determined accordingly. |