WRDS) Library
Total Page:16
File Type:pdf, Size:1020Kb
This is a digital document from the collections of the Wyoming Water Resources Data System (WRDS) Library. For additional information about this document and the document conversion process, please contact WRDS at [email protected] and include the phrase “Digital Documents” in your subject heading. To view other documents please visit the WRDS Library online at: http://library.wrds.uwyo.edu Mailing Address: Water Resources Data System University of Wyoming, Dept 3943 1000 E University Avenue Laramie, WY 82071 Physical Address: Wyoming Hall, Room 249 University of Wyoming Laramie, WY 82071 Phone: (307) 766-6651 Fax: (307) 766-3785 Funding for WRDS and the creation of this electronic document was provided by the Wyoming Water Development Commission (http://wwdc.state.wy.us) HEART MOUNTAIN CANAL REHABILITATION LEVEL II STUDY AMENDED FINAL REPORT August 2017 Prepared for WYOMING WATER DEVELOPMENT COMMISSION Prepared by Engineering Associates P.O. Box 1900 Cody, WY 82414 HEART MOUNTAIN CANAL REHABILITATION LEVEL II STUDY AMENDED FINAL REPORT FUNDED BY: Wyoming Water Development Commission DIRECTOR: Harry C. La Bonde, Jr., PE COMMISSIONERS: Nick Bettas Karen Budd-Falen David Evans Gerald Geis Clinton W. Glick Kellen Lancaster Sheridan Little Jeanette Sekan Larry Sucher Rodney Wagner PROJECT MANAGER: Dave K. Myer, PE CONSULTANT: Engineering Associates P.O. Box 1900 902 13th Street Cody, Wyoming 82414 (307) 587 -4911 DATE: August 2, 2017 JOB NUMBER: 15108.00 TABLE OF CONTENTS CHAPTER ONE - INTRODUCTION ................................................................................ 1 A. Background .................................................................................................................................. 1 B. Amended Scope of Study………………………………………………………………………….. 1 C. Abbreviations and Definitions………………………………………………………………..…….2 CHAPTER TWO - HYDRAULIC ANALYSES ................................................................. 3 A. Original Hydraulic Properties .................................................................................................. 3 B. Preliminary Design Analyses .................................................................................................. 3 CHAPTER THREE - REHABILITAION PLAN ................................................................ 5 A. Canal Options……………………………………………………………………….……………...…. 5 B. Access Road……………………………………………………………………………………......… 6 CHAPTER FOUR - PRELIMINARY LEVEL DESIGNS AND COST ESTIMATES… .. …. 8 A. Cost Alternate 1………………………………………………………………………………………. 9 B. Cost Alternate 2…………………………………………………………………………..………… 10 C. Cost Alternate 3…………………………………………………………………….………………. 11 D. Cost Alternate 4…………………………………………………………………………….………. 12 CHAPTER FIVE - SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS ........... 13 A. Summary .................................................................................................................................... 13 B. Conclusions ............................................................................................................................... 13 C. Recommendations .................................................................................................................. 13 Appendix A - Preliminary Level Designs Appendix B - Response to Statutory Requirement Concerning Private Enterprise CHAPTER ONE INTRODUCTION A. BACKGROUND The Heart Mountain Irrigation District (HMID or District) is one of 4 entities delivering irrigation water that is collected behind the Buffalo Bill Dam, west of Cody, Wyoming. The original dam construction took place between 1904 and 1910. A penstock was placed through Cedar Mountain to carry reservoir water downstream to a hydro power station and to the 14-ft diameter steel siphon that carries irrigation water over the Shoshone River. The water then enters the Rattlesnake Mountain Tunnel, before discharging into the beginning of the Heart Mountain Canal. B. AMENDED SCOPE OF STUDY Following the submittal of the Final Report in September, 2016, Heart Mountain Irrigation District discussed their desire to amend the Final Report to include a 10-ft x 20-ft concrete rectangular channel analysis and cost estimate. The Wyoming Water Development Commission considered this request in March 2017, and agreed to an amendment to the scope of study. This Amended Final Report addresses those additional considerations approved by WWDC. This Amendment is to provide supplemental information to the previously released report completed last year. The Amendment consists of additions to previous analyses and specifically focuses on two cross section options for canal replacement: one involving a rectangular cross section, and one involving updates and clarifications to the previously defined trapezoidal cross section. Additionally, information is provided pertaining to construction access to the project site. Deliverables include both hard copies and digital copies of the report amendment in draft and final versions and an amended executive summary. The Amendment primarily focused on the following tasks: 1. Task 4 - Hydraulic Analysis: a. Use hydraulic analyses to look at the cross-section design, slope, velocity and water depth to determine if a 10-ft x 20-ft rectangular channel would be an adequate alternative to the existing trapezoidal shape. 2. Task 5 - Rehabilitation Plan: a. Create conceptual designs and construction cost estimates for the rectangular cross section. b. Update the conceptual designs and construction cost estimates for the trapezoidal cross section. c. Review transportation accessibility to the remote canal rehabilitation site and identify improvements and costs associated with improving the existing canal road. 3. Task 8 - Reports: a. Creation of the Final Amendment Report and Amended Executive Summary. For additional information, please see The Heart Mountain Canal Rehabilitation Level II Study – Final Report, dated September 2016. C. ABBREVIATIONS AND DEFINITIONS AC Acre AF Acre Feet BLM Bureau of Land Management BUREC Department of the Interior Bureau of Reclamation CFS Cubic Feet Per Second FT Feet GPR Ground Penetrating Radar GPS Global Positioning System HMID Heart Mountain Irrigation District IN Inches LF Linear Feet SF Square Feet - 2 - CHAPTER TWO HYDRAULIC ANALYSES A. Original Hydraulic Properties Heart Mountain Canal was designed in 1938 by the Department of the Interior Bureau of Reclamation (BUREC) for the Shoshone Project. The original hydraulic properties that were used for design of the liner are shown below. Area Velocity Flow, Q Manning’s Coefficient Hydraulic Radius Slope (sqft) (fps) (cfs) (n) (ft) (ft/ft) 130.58 7 914 0.014 4.08 0.00068 This original design was used to determine the design flow depth (y) for this canal section. The original design depth was 7.48 feet, leaving 1.52 feet of freeboard in the 9- foot high constructed trapezoidal canal section. B. Preliminary Design Analyses 1. Design Parameters The original design parameters of 914 cfs and a slope of 0.00068 ft/ft would be used for all proposed hydraulic design. The District in the past 30 years has not had that amount of flow in the canal, but any new designs should be in line with the original BUREC design criteria. Because the existing liner lies between two fixed elevations, it would not be prudent to modify the design slope by a significant factor. The liner is situated directly downstream of the Shoshone Siphon and the Rattlesnake Tunnel. Any design parameter changes proposed for the liner would impact both of those upstream structures. Thus, maintaining current design water level will assure that this will not occur. 2. Trapezoidal Cross Section Replacing the existing liner with a new concrete liner and holding all dimensions and design parameters from the original design, with nominal changes to the floor/wall intersection, should allow the design maximum flow of 914 cfs. The addition of 1.5-foot side walls would provide a freeboard of 3.02 feet, doubling the existing freeboard. 3. 10-ft x 20-ft Rectangular Cross Section Assuming a conservative Manning’s coefficient of 0.015 and a slope of 0.00068 ft/ft, the 10-ft x 20-ft rectangular channel design will carry a design flow of 914 cfs with a flow depth of 6.92 ft. This will provide a freeboard depth of 3.08 feet (10-6.92) and a velocity - 3 - of 6.60 fps. This velocity is slightly lower than the trapezoidal channel velocity of 7 fps. Though the rectangular channel design is less efficient hydraulically than a trapezoidal channel, it will provide minimal changes to the flow characteristics upstream and downstream from the lined section because of the similar flow depth and velocity to the original design. - 4 - CHAPTER THREE REHABILITATION PLAN There were several rehabilitation options examined in the Final Report to improve or replace the existing liner. These options for concrete liner rehabilitation were narrowed down to two and are addressed in this amendment: 1) a trapezoidal shape or 2) a rectangular shape. Preliminary design details for both of these options can be found in Appendix A. A. Canal Options 1. Trapezoidal Cross Section: Option 1 consists of complete reconstruction of the trapezoidal-shaped liner, including the inlet and outlet transitions. The existing liner would be removed and any voids encountered would be filled with cement-treated backfill (CTB). A geotextile fabric would be used to bridge across the filled void between the CTB and the foundation rock. Finally, a new concrete trapezoidal-shaped liner section would be