Powerline Plan and Environ. Assessment Jan. 2013 - Flood Control ...

Powerline Flood Retarding Structure
Pinal County, AZ
Draft Supplemental Watershed Plan
and Environmental Assessment
LIST OF TABLES
Table 3-1 Evaluation of Identified Concerns .............................................................................. 3-1
Table 4-1 Non-Inclusive Listing of Vegetation ........................................................................... 4-5
Table 6-1 Summary and Comparison of Candidate Plans – NED Account .................................. 6-9
Table 6-2 Summary and Comparison of Candidate Plans – EQ Account................................... 6-10
Table 6-3 Summary and Comparison of Candidate Plans – OSE Account ................................ 6-12
Table 6-4 Effects of the Alternatives on Resources of National Recognition............................. 6-13
Table 8-1 Summary of Powerline Channel Geometry and Results. ............................................. 8-2
Table 10-1 List of Preparers ..................................................................................................... 10-1
LIST OF NRCS NATIONAL WATERSHED MANUAL TABLES (SECTION 8)
NRCS Table 1 - Estimated Installation Cost ................................................................................ 8-9
NRCS Table 2 - Estimated Cost Distribution - Structural and Non-Structural Measures ............ 8-10
NRCS Table 3b - Structural Data – Channel Work, Powerline Channel, Pinal County, AZ........ 8-11
NRCS Table 4 - Estimated Average Annual National Economic Development (NED) Costs ..... 8-12
NRCS Table 5 - Estimated Average Annual Flood Damage Reduction Benefits ........................ 8-13
NRCS Table 6 - Comparison of NED Benefits and Costs .......................................................... 8-14
LIST OF FIGURES
Figure C-1. Powerline FRS Existing Embankment - Typical Section
Figure C-2. Powerline FRS Principal Spillway
Figure C-3. Powerline FRS Auxiliary Spillway
Figure C-4. Earth Fissure Risk Zones
Figure C-5. Plan View Preferred Alternative
Figure C-6. Proposed Powerline Channel – Typical Section
Figure C-7. Proposed Powerline Channel – Hardened Typical Section
Figure C-8. Plan View of Proposed North Diversion Channel
Figure C-9. Proposed North Diversion Channel - Typical Section
Figure C-10. Emergency Spillway Inundation Areas – Powerline FRS
Figure C-11. Dam Failure Inundation Areas – Powerline FRS
Figure C-12. 100-year Floodplain Mapping with Dams In-Place
Figure C-13. 100-year Floodplain Mapping without Dams In-Place
LIST OF APPENDICES
Appendix A. Comments and Responses
Appendix B. Project Map
Appendix C. Support Maps
Appendix D. Investigation and Analysis Report
Appendix E. Other Supporting Information
Appendix F. Compact Disk (CD)
USDA- NRCS Page vi January 2013
Kimley-Horn and Associates, Inc.