Dam Foundation Erosio·n - Bureau of Reclamation Foundation Erosion Study Team Dam Foundation Erosio·n 1994 Year End Summary Report Study Team: Rodney J. Wittler, James F. Ruff, Steven

Dam Foundation Erosion Study Team

Dam Foundation Erosio·n 1994 Year End Summary Report

Study Team: Rodney J. Wittler, James F. Ruff, Steven R. Abt,

George W. Annandale, Brent W. Mefford

PG&E Project Manager: Kiran Adhya

EPRI Project Manager: Doug Morris

April 12, 1995

\

LJ

l.

0 0 D 0

,,

Table of Contents TABLE OF CONTENTS .. . . ........... ... . ... .. .. . . .. .. .. ... ... . . .. .. . .. ........... . .. .. . . .... . .... . .. .. . . ... . . . ... . .. .. . .. .. ... .. . . .... .. . . . . . .... ... .. . . ... . . ... ... . i TABLE OFFIGURES .. ..... . .. . . . . .. . .. . .. . .. .. ... . .... .. . .. .......... . ..... .. ........ ... . .. .. .. .. ............. . ... .. . ... . . . .. .... . . . .... . .. . ....... . .. . .......... . .. iii TABLE OFT ABLES ...... . ... . .. . . ... ...... . . . . . ... .. ... ............. .. .......... . ... ... ..... . ..... . . . .. . . . . . ...... . . . . ....... . .. ... ...... . . .. .... . .... . ...... . ... .. . iv ABOUT THE AUTHORS ...... . ....... ....... .. .... .... ......... . ... ... . . ....... . ......... ........ . .... . .. ... ..... . ... .. ..... ... . .. .... .... . . ........ .. ...... . . ... ... V

STUDY TEAM ORGANIZATIONS .. . .... . ........ ........ ........ .. .......... . .... . ....... ........... .......... .. .... . ... . . .. . .. . .. .. . ... .... ......... . .... .. .... V

ACKNOWLEDGMENTS .. . . .. .. .... . .. . . . . . . . ..... . ....... . ... ...... . . . . . . .. .. . .... .. . .... ..... . .' . . .. . .. .. .. .. ..... . . .. ........ . ...... ........ . . . ..... . . .. .. .. .. . .. . vi KEY WORDS . .... .. . ... .. .. ..... .... .. .. . .... ...... ............ .. .. ............. . . . ... . . .. .. .. . . .. ....... . ... . ..... . . . . ... . ... . ... .. ... . . . .. . . . .... . ... . ..... . . . . . .... vi EXECUTIVE SUMMARY .... . ... . .. . .. . . .. . . .. . . . .. . ... .. .... .. ..... . . .. ...... . . . ........ .. . . . . . . .. . .. . ... . .. ... . .. .. ... .. . . . ... . . ... ... .. . . . ... . . .. .... .. . ...... . vii

INTRODUCTION ................................................................................................................................................ 1

STUDY BACKGROUND ... . .... ..... . ... . ... . ... .. .. .. ... . .. .. . .. . . ... ... .. . .. . . .. .... . ..... . . . .. . . . .. . ... .. ..... . ... ......... . . . . ........ . ... . .. ... .. . . ... . .. .. . . . . 1 Quarterly Schedule of Activities: Q4 1992- Qi 1995 .... .. ... ... ... ...... ......... ... .. ..... ........ .. .. .... ... .... .... .. ... ...... ........ 2

FINANCES .................................................................. ................................................................. , ...................... 5

ROLES OF COLLABORATING.ENTITIES· ····· · ·· · ···· ·· ·· · · ·· ·· ·· · ·· ········ ·· ···· · ··· · ·· · · · ···· · ··· ·· · · ······· ········· · ··········· ··· ···· · ·· ·· ···· ·· · · ···· · 5 Summary ..... .. ...... .... ..... .... ... ... ...... .. ....... ......... ... .................. ... ........ ... ... .. ....... .. ......... ... .. ... ... ...... .... ...... ... ... ......... 7

FUNDING SUMMARY .... .. ........ . . ..... . ..... . ... ... . . . . .. . .. .... ............... . ... ... . ... ... ... ... ... ...... ... .. ........ . .... .. . .. .... ... ... .. ... . ... ... .... .. .. 7

EXPENSE SUMMARY . ... . .... . . .. . ... . .. . .. .... . ... ... .. . . . . . .... .. . ... . .. ........... ............ ......... . .. . .... .... . . . ... . .... . .. . . . . .. . . . ... .... . .- . .. . ...... .. .. 7

SCHEDULE .... ..................................................................................................................................................... 9

SCHEDULE ......... . .. .. .. ... .. .... . .... ... ..... ... . .. . . . ... .. ... . . . .... .. . .... •.... . . . . .. . . . . . ....... .. . . .. . ... ..... .. ... . . ; . ..... . . . . . .... . .. . .. . .. . . . . .... . ... ..... . . 9

CALENDAR 1995 TASKS ··· ····· ·· ·· ·· · ·· ·· · · ······ · · ···· · ·· ·· · · · · ·· ···· ·· ···· · · · ·· ·· · ·· ····· ·· · · · ···· ······ · · ·· · · · · ·· ···· · ···· ···· ·· ·· · · ··· ······ · · ·· ·· ······ · · 10

PROTOTYPE MODEL DESIGN ..................................................................................................................... 11

PROTOTYPE PLANS .. .. ..... ... . . .. . .. ..... .. ........ .. .. .. .. ... . . . . . . ... . .. .. . . ... .. ........ . ..... ............ .... ............ .. ..... . . . ... .. . . . .. . ...... . ... . . ... 11 FEATURES OF PROTOTYPE DESIGN .. .. .. . .. ... . ........ ... ... .. .... . ... . . ... ... . . . .... .. ... .. .... . . ........................ . . ....... .. ........ ... . ..... . ... 17

SCALE MODEL DESIGN ................................................................................................................................ 21

FACILITY PLANS .... . . .. ..... ........ . .. . . ......... ... .. .... ..... . .... . . ...... . ...... .... . ... .... ..... . .. .. . ...... .. .. . ............ ...... . .. .. . ....... . ..... .. ..... 21

0 ,RIFICE DESIGN & TESTING .. . . . .. ... ... .. . . . ... . .. .. ..... . .... ..... ....... . .... . . ... . .. ... .... ... .. .. . . .... . .... ... ... ...... . .. . .. ....... .. . .... . . . . . . .. . . . . 26

PIT 4 EXPERIMENTS .. ....... .. .. . ... .. . .. . .... .. . . .. . . .. ................... . .. .. . .. ......... . . . .... .. .. . . . ... . ... .. ... ........... . ... . . .. ......... .. . . .... ..... .. 29

Executive Summary .... .... ..... ... ...... ... ... .......... ... .. .............. ... .... ........ .......... .. .. .... ... .... ... .......... .... .... ...... ... ...... .... 29

PUBLICATIONS ............................................................................................................................................... 31

PRE-TEST REPORT AND SURVEY OF LITERATURE .. ....... . ... . ..... .. . . . .. ... .. ..... ... .... ... ..... .... .. .. .. .. . ..... .............. . ... . ..... . .. . .. . 31

Pre-Test Report ... ..... ... ...... ........ ... ... .. ... ..... .... ... .... ........ .. ........ ... ..... ... .... ... .. .......... .... .... ... ......... ...... .... ........ ... .. 31 Survey of Literature ... .. ...... .. ... .... ... ...... ........... .... ... .. ....... .... .. ... ...... ... ..... ... ... ...... ...... ..... ....... ...... .... .......... ....... . 32

Teclmiques For Predicting the Erodibility of Earth Materials .. .......... ..... ........ .. ... .... ....... .... ..... ..... .......... .... ... .... ...... ....... 32 Techniques For Estimating the Extents ofErosion ... .... ... .... .. ..... ... .. ....... ..... ... .... ...... ........ ... ... ... .. ... ... ..... ... ...... .. ....... .... .. 32 Techniques For Estimating the Progressive Extents of Erosion .. ......... ... .. .... ..... ... .... ...... ...... ......... ......... ..... ... .... ........... . 33 State of the Art .. .. .... ...... ... ....... ..... ..... ..... .. .... ............ ... .... ....... ........ .... ... .. ........ .. .... .. ..... .. ... .... .. .. ... ... .. .... .... ... ...... .. ..... ... 33

Maximum Scour or Erosion Depth .... .. ........ ...... .... .. .. . : ...... ... ....... .. ........... ... .. ................. .. .. ..... ...... ....•.... ..... ... .... ..... .. 33 Air Entrainment ............... ..... ................ .......... .. .... ..... ...... ... ... ........ .. .... ... ..... ... .... ... ..... ....... .. .. ....... ..... .... . : .... .... ........ 34 Erosion Extents and Progressivity .... ... ......... .. .... .. .. .... .... ... ........ ..... ..... .... ... .... ...... .......... .. .... .. ... .. ....... .... ... ........ ...... .. 34

Conclusions ...... ..... .............. ... .. ... .... .... ....... .. ..... .... ... ... ... ............ .. .. ... .... ........ .. .................... .... ......... .... .... ... .... ... ....... ... 37 PUBLISHING SCHEDULE ........ . .. . .. . . . . ........ ... ... . ... . .. ... . . .... . ............... . ... ........ . . . .. . ... ........ ........ ... .. .. ...... . .. .. .. . ..... ... ....... 37

APPENDIX A .......................... ..................................................................................... .................................... A-1

SCOPE OF REMAINING WORK .. .. . .. .. ....... . . . . .. . . . . .. . .. . ...... . ..... . ...... .. . .. .. .. . ..... ....... ...... . ...... . ..... . ............ . ..... ........ ........ A-1 Dam Foundation Erosion: Pre-Test Report .... .. ... ... ..... ..... ..... ... ... .... ...... .. .. ... ..... .. ... .. .... .. .. ... ........ ... .... .. ..... ..... ....... .... .... A-1

Overview ... .... ... ... ........ .... .... ...... ..... ..... .. .... ... ..... ............. .......... .... ... .. ........ ...... ....... ... .. ..... ........... .. .. ...... ...... ... A-1 Overview of Experiments ... ... ... ..... ................. ..... ... .. ... ......... .... ...... .... ..... .... ......... .. ... .... ... ............... .. ............ .. A-2

Hydraulic Experiments ......... .... .... .......... .......... .. ... .... ... ... .. ... .. .. ...... .. .... ... ..... ..... ... ... ...... ....... .. .... ... ......... ..... ... ...... .... ... A-3 Material Experiments .. .... .... ... ... ...... ....... ..... ...... .... .. ...... ....... ........... ... ... ............ ........... ... ........ .. ....... .. ... ... ...... ... ....... .. A-4

Dam Foundation Erosion Table of Contents • i

/ \

D Details of Scale Model Facility Experimental Series ...... ................. ... ................ ..... ............................ ............ A-4

Experiment Series in the Scale Model Facility ...................................................... ....... ... ................. ......... .................. A-4 Facility Operation ............. ... .... .. ...................... ........ ...... ............ ..... .... ..... ... .... ........ .... ..... ........ .... .... ............. .... .... .. A-4 0 Instmmentation Design ... ....... .. .... ......... ........... ... ......... ... ... ...... .... ...... .. .. .... ... ..... ... ..... ....... ... ......... ..... ... .......... ... ..... A-5 Clear Water Hydraulic Experiments ........... ..... ..... ........ ... ............... .. .... ...... .. ....... ... ... ........ .. ........ .. .... .. ...... ........ ..... A-5 Granular Media Experiments ..... .. ... ...................... .... ... .... .. .... .... ...... ....... ..... ..... ....... .. .... ...... ........ .. ... ........ ... ........... A-5 Simulated Earthen Material Experiments ...... ... ... ........ .... .... .. ...... .... ...... .... ............... .. ....... ... ... .... .. ....... ................. . A-6 0 Granular Media Experiments: Temporal Effects ....... .. ......... .... .. ................................................................ .. ..... ... .. A-6 Summary ........................ ...... .... ..... ............ .... ............... ..................... ......... .. ............................................. ............. A-6

Details of Prototype Scale Facility Experimental Series ....................................................................... .......... A-7 Facility Plans ..... ..... .. .. ... ...... .............. ... .... ..... ... ...... ................. .... .......... ............ ....... ..... ... .. .. .... ............... ..... ...... ........ A-7 Experiment Types in the Prototype Model Facility ........ ....... .... .. .... .. ... ... ...... ... ............. ... ....... .. ............. ........ ... ....... .. .. A-8

Facility Operation ................... .... ........... ........ ............... .... ... .... .... .. ..... ... ... ..... ...... ... .... ... ... ..... ... ... ..... ... .... ... ............ A-8 Clear Water Correlation Experiments .... .. .... .. ..... ........ ..... .. ... ..... ................. .... .... .. .... .. ... ....... ..... ... ... .... .... .. .. ......... .. A-8 D Granular Media Correlation Experiment ..... .... .... .. ...... .. ... .. ...... .. .... .. ... ..... .... ... ..... ..... ..... ... .... ......... ...... .... ... ... .... ..... A-8 Cubical Slabs ...... .... .... ........ ... ............... ... ..... ... ............... ......... .. .... ............... ... ......... ... ........ .. ....... .. ...... ........ .. .... ... A-8 Vertically Oriented Slabs .. .. .... .... .... ... ............ .. ..... .. .... .... ... .. .................. ... ............... .. .......... .. .... .......................... .. A-8 Upstream Oriented Slabs .. ... ....... .. ....................................................................................................... ........ : ......... . A-8 n Downstream Oriented Slabs ... .......... ... .......... .. ......... ...... ..... .. .... ...... .... ... ... .......... ... .... ................. .. ...... ... ................ A-8 Cohesive Material ................................. ...... ............. ... .. .. .... ....... ..... ..... .... .. ...... ..... ........... ..... ..................... ............ A-9 Cohesive Material in Slab Joints ... .... .. .. .. ........... .. .. ........ ... .. .................... .. ..... .. ........ ............ .. .......... .. ........ .. ... .... .. . A-9 Noncohesive Material in Slab Joints ... ..... ......... ........ ... .... .................. ..................................................................... A-9 f J Additional Experiments ......................... .. ......... .............. ...... .... .. ..... ...... .... ... .. ........ ..... .......... .................... .... ......... A-9 Summary ............. ..... .... .. ........ .. ... ........ .... .... .. ...... ..... .. ...... .. .. ... ...... ......... .. .. .. ... ...... ... .. ...... ... ... .......... ...... ... .... ...... ... A-9

Numerical Model Developments ........................................................... .................. ... .. ..... .... ... .......... ... ..... ... A-JO Graphical Basis & Progranuning .. .. ... .............. ....... ..... ..... ... .... ... .. ...... .. ........... ............ ....... .... .... ...... .... ... ......... ......... A-10

0 Segmented Process Simulation ... ........ ......... ........ ...... ..... ......... ..... .......... .. ... .... ...... .... .. .. ..... ... ............ ........ ....... ........ . A-10

Hydrology ................. .. ... .. .. .... .... .................. .................................. ... .... .... ......... ...... ...... ... ........... ...... .... .. ..... ... .... A-10 Hydraulics ... ...... .. ....... ....... ... ... ........ ...... ........... ......... ......... .. .......... ..... ............ .......... ......... ........ ... ........ ..... .... ...... A-10 Plunging Jet ... ..... ........ .. ............ ...... ... .... ... .... ... ............ ............ ... ........................................... ..... ......... .... .... ........ A-10 Supported Jet ................ .... ........ ... ... ...... ... ........ ..... .......... ... .... .... ... .... .......... .. ....... .... ... ....... .. ............. ... ............... . A-10 Jet!failwater Interaction .......................... ...... ... .............. ... ............................... ...... ............ .... ..... .... .. .. ... .. .. .......... A-10 Erodibility ....... .... ... .............. ......... .... .. .. .... .................. ..... .... .... ... .. ..... .... ................ .. ... ....... .. .. ........ .. ..... .... ..... .. .... A-11 Foundation Material/Jet Interaction ... ...... ............. ... ... .. .... ........ ... .... ............ ....... ... .... ... ... .... ......... ........ ........... ..... A-12 Mass wasting ... .. .............................................................. ..... .. ... .... ..... ... .. ... .. .......................... ......... ... ... ....... ... .... A-12 Displacement ....... ... ... ....... ... .. ........... .... .. .... .. ........................................................... ... ........... .. ... ... .. ... .. ............... A-12 Mounding ..... ..... ........ ........ .... ....... ................. ..... .. .... .... .... ...... ..... ....... ... .. .... ..... ... .. .. .. ................. ..... .... ..... ........ .... A-12 Tailwater. ....................................................................................... ... .................................... ... .... ... .......... ... ." ....... A-12

Refinement Process .... ... ... .... .. ... .. .... .. ....... .......... .... .. ...... ... .. .......... ... ....... ... .. ...... ..... ... .. ... .. .. .... .......... ... .... ................. A-12 Reports & Jvleetings .... .............. .... .... .. ... ....... ......... ............. ...... ..... ... .. ................ .... ... ..... ... .. ... ................. ..... A-13

Meetings ..................... ................................................... ................................................................... ... .. ..... .. ..... .. ..... A-13 Reports ........................................................................ "' .. : .. .. ............. .......... .. ... ........................................................ A-13

References ..... ............ ................. .. ....... ... .... ..... ..... ..... ... ......... .... ... .. ...... ........... •. ...... .... ... .. ... ... ................... . :.A-15

APPENDJXB ................................................................................................................................................... B-1

STIJDY SCHEDULE ........... ... .. .... ......................... . .. ........................... , . . ............. ........ .... .. .. ........ .. ... .. ... ..... .... ... .. ..... B-1

Dam Foundation Erosion Table of Contents • ii

Table of Figures FIGURE 1. OVERALL PLAN VIEW OF DAM FOUNDATION EROSION FACILITY IN RELATION TO EXISTING OVERTOPPING

RESEARCH FACILITY AT COLORADO STATE UNIVERSITY . . ....... ..... . . . ..... . .. . . . ... .. ... ...... ......... . ... . . .. . .. .. . .. ........... .. . 11 FIGURE 2. PLAN, SIDE, & FRONT VIEW OF PROTOTYPE FACILITY . ... . ... . . . . . . . ... . ......... ... ......... ....... ...... . ... ... . ..... . .. . . . .... . 12 FIGURE 3. TEST BASIN STRUCTURE DETAIL, PROTOTYPE FACILITY. PLAN VIEW . . ..... . . .. . . ................ .. . .. . .. . ... ...... .. . . ... . 13 FIGURE 4. TEST BASIN STRUCTURE DETAIL, PROTOTYPE FACILITY D,'TENDED BOX OPTION . .. . .. . . . ... . .. . ... . . . ... ...... ..... . . . 13

FIGURE 5. VIEW A-A, REBAR PLANS. ············ ·· ·· · ··· · ·· · · · ····· · · ·· ···· · ·· ·· ·· ··· ·· ·· ····· · · ········ · ···· · ·· ···· ·· · · ·· · ·· · · · ··· ··· · ···· · · ·· ···· ·· · · · 14 FIGURE 6. VIEWS B-B AND C-C . . .................. . ... . . .. .. .... ...... ..... .. . . ... ... . .. .. ... .... . ...... ... . . ..... .... . . . . . . . . . .. . . .. . .. ... ... .. . . .. .. .... 14 FIGURE 7. SECTIONS E-E, D-D, AND SLAB DETAIL. . . ... . .. ... .... ............ ...... .. .. ... . .. . . . .. . . ... . . .. . ...... . . . .. .. .. .. . . .. . ..... . . . ... ..... 15 FIGURE 8. VIEWF-F . . . . . . . .. .. ........... . . . .. .. . . . .. . .. . .. .. . . . ... . ... ...... . .. .. . ....... . . . . . .... .. . . . .. ... . .. . ...... ... . .. . . . ... . . .. .. ... ...... . . ..... .... . .. 15 FIGURE 9. PLATE DETAIL . . ....... ...... .. . .. .... ......... ... .. . ... ... . .. .. ........ ... .. . . .... ... · .. ... . ... . .. . . . . .. ... . . .. . . .. .... .. .. . .. .. .... . ...... ... .. .. . . . 16 FIGURE 10. FOOTING DETAIL. . .... ..... . .. . .. . .. .. .. . ... .. ..... . . .. .. . . ... . .. .. . ...... . . ... .... . . . .... ... .......... . ..... .. .. . ........ . ...... . . . .. .. ....... . 16 FIGURE 11. PLAN VIEW OF 0VERTOPPING FACILITY . . .. .. .. .. . .. .. .... ...... . . . . ... .. . . . .. . . .. . .... . .. .. .... ... . ... . ... ... . . . . . . .. .... . .. . ... .. .... 17 FIGURE 12. PROFILE OF 0VERTOPPING FACILITY . . . . .. . .. ... .... .. .. .. . .. . . . . .. . . . .... . .... . . ................ . .... . ...... . .. . .. . ... . .. .... .... .. . . . . 18 FIGURE 13. AREA PLAN OF 1:3 SCALE MODEL FACILITY WITH WALKWAYS, PLATFORM, ST AIRS, TEST BASIN, AND

ORIFICE .... .. . .. .. . ... . . ..... . ...... . . . ...... . ... . ..... . .............. . .. . . . . . . . ... .. ..... .. ... . . .... ..... .. . .... ... ..... . ............. .. . . . . .... : . . .... ... . . . . 21 FIGURE 14. DETAILED PLAN OF BASIN AND ORIFICE ... . ....... .... .... ...... . .. .. .. . . .. .. . .. . .... .. ... .. . ... ... . .. ..... . . . .... . ... . ... .. ... .. . .. .. . 22 FIGURE 15. ELEVATION OF 1:3 FACILITY FROM WASTEWAY (DOWNSTREAM) PERSPECTIVE .... ... .... ... .... . ... . .. ... .. . .. . .. .. . 22 FIGURE 16. SIDE ELEVATION OF BASIN WITH ORIFICE .. .. . .. ... ..... .. . . .... ... .. . .. .. . .. . ...... . .. . .... .... . ....... . . . ... . ..... . ... . ......... .... 23 FIGURE 17. ORIFICE DISCHARGE PIPE . .... . ................... .... . .. . ....... ........... . .... . ....... ...... ..... . .................... . . .. ... ... . .. ...... .. 23 FIGURE 18. ORIFICE PLATE DETAIL. .. . ... . .. .. .. .... . ........ .. ....... ............ . . . . . . .. . . . . ......... . .. ... ... .. . .. . . ... . ... .... .. ... ... . .... . ..... .... . 24 FIGURE 19. CROSS SECTION A-A. DETAIL OF ORIFICE BLADES. (UPPER HALF ONLY) ... . ........... . ......... .. ....... . . . .. ........ 24 FIGURE 20. CROSS SECTION B-B. DETAIL OF INNER AND OUTER PIPING CONFIGURATION. FLOW ENTERS THROUGH

THE INNER PIPE/MANIFOLD INTO THE OUTER PIPE ... . .. .. . ........ .. . . .. .. .......... . .... . ............ . .... .. .. . ............... . . ... .. .. . .. . . 25 FIGURE 21. 8" MANIFOLD OUTLET PATIERN . .............. . .. . .. . ...... . . . ... .. . . ...... .. . . . . ... ..... . ..... . .............. . ...... .. ... ... . ... ... . . .. 25 FIGURE 22. PLAN OF PROPOSED ADDITIONS AND MODIFICATIONS TO EXISTING OVERTOPPING FACILITY AT COLORADO

STATE UNIVERSITY. NOTE TAP INTO EXISTING WATER SUPPLY SYSTEM AND COMMON USAGE OFT AILBOX AND

WASTEWAY .. . . .. ..................... . . .. .. . .. ... . . . .... , . ... . . . .. .. ... .. . . .......... .. . .. ..... . ... ... . ... .. . .. . . . .. . ........ ... . . . . ... . ...... .. ... ....... A-7 FIGURE 23. VIES OF THE PROTOTYPE SCALE FACILITY . . ...... ...... . . . .... ....... . .. . .... .. .. .. . . ... . .. ... .. .... . . .... .. ..... ..... .... . . . . .. . .. A-7 FIGURE 24. STREAM POWER VERSUS ERODIBILITY INDEX SHOWING THE EROSION THRESHOLD .. .. .. .. .. ...... . .. . .. . . ..... A-11

Dam Foundation Erosion Table of Figures • iii

Table of Tables TABLE 1. QUARTERLY ACTIVITIES OFTHEDAMFOUNDATIONEROSION STUDY ..... ......................... ..... .......... ............ 2 TABLE 2. FUNDING SUMMARY ................................................................................. ................... .. ..... ..................... 7 TABLE 3. ITEMIZED COST SUMMARY FROM INCEPTION TO PROJECTED END OF THE STUDY ............ ......... ............. .. ....... 8 TABLE 4. TASK LIST FOR REMAINDER OF DAM FOUNDATION EROSION STUDY ............................................................ 9 TABLE 5. SUMMARY OF ORIFICE DESIGN TESTS IN THE SCALE MODEL FACILITY ............................................ .. ......... 28 TABLE 6. SUMMARY OF TASKS .......................................................... ... ............................ ..... .............................. A-3 TABLE 7. EXPERIMENT SERIES FOR IDENTIFYING TEMPORAL EFFECTS OF EROSION .............................. .. ........ .. ........ A-6

Dam Foundation Erosion Table of Tables • iv

D 0

0 0 D Li

Li

J

About the Authors Dr. Steven Abt, Hydraulic Laboratory Director & Hydraulics Program Coordinator, Colorado State University, is the Scale Model Team Leader for the Dam Foundation Erosion study.

Dr. George Annandale, Manager: Water Resources, HDR Engineering, is the Numerical Modeling Team Leader for the Dam Foundation Erosion study.

Mr. Brent Mefford, Hydraulic Engineer/Technical Specialist, Bureau of Reclamation, is a Peer Reviewer and Technical consultant for the Dam Foundation Erosion study.

Dr. James Ruff, Professor of Civil Engineering, Colorado State University, is the Prototype Model Team Leader for the Dam Foundation Erosion study.

Dr. Rodney Wittler, Hydraulic Engineer, Bureau of Reclamation, is the Study Team Leader and Principal Investigator for the Dam Foundation Erosion study.

Mr. Kiran Adhya, Senior Consulting Engineer, Pacific Gas & Electric Company, is the PG&E Program Manager for the Dam Foundation Erosion study.

Mr. Doug Morris is the EPRI Project Manager for the Dam Foundation Erosion Study.

Study Team Organizations The mission of the Bureau of Reclamation (Reclamation) is to manage, develop, and protect water and related resources in an environmentally and economically sound manner in the interest of the American Public. Reclamation is responding to the challenge to help develop the West by providing sustained economic growth, improving the environment, and enhancing quality of life. In the future Reclamation will be meeting increasingly complex water demands and resource management needs of the West.

The Electric Power Research Institute (EPRI) conducts a far-reaching program of collaborative research and development on behalf of the nation's electric power industry. Today some 350 EPRI scientists and engineers manage nearly 1600 research projects related to the efficient generation, delivery, and use of electricity, with special attention paid to cost-effectiveness and environmental acceptability. Roughly 700 electric utilities fund EPRI research through membership payments and project investments. Research and development, in the form of products, services, and information, contribute directly to the benefit of EPRI members and their customers.

Pacific Gas & Electric Company (PG&E) is a privately owned public utility company providing electric and natural gas service to customers in Northern and Central California. PG&E electric power sources include hydro, geothermal, fossil, and nuclear generation. PG&E's hydroelectric capacity is 3,874 MW from 67 plants, mostly from sites on the western slope of the Sierra Nevada. More than 130 impounding and diversion stmctures ranging in size from the 335-foot high Salt Springs Dam to small canal diversion stmctures make up the Hydro sources . The company has a strong research and development program addressing dam safety and other Hydro issues .

Western Area Power Administration (Western) markets hydroelectric power from more than 50 power plants at Federal dams throughout the western United States. The dams and power plants are owned and operated by the Bureau of Reclamation, the US Army Corps of Engineers, and the International Boundary and Water Commission. Western also markets a share of the power from the Navajo Generating Station. Westem's mission is to market Federal hydroelectric resources in such a manner as to encourage the most widespread use thereof at the lowest possible rates to consumers consistent with sound business principles.

Dam Foundation Erosion About the Authors • v

V\A.. (\(\ (\,.

Colorado State University (CSU), founded in 1870, is the land grant university in Colorado. The Civil Engineering Department enrolls roughly 350 undergraduate and 200 graduate students. Recent research by Civil Engineering faculty includes river mechanics, bank stabilization technology, environmental methods in stream rehabilitation, drop structures, stream monitoring, and embankment overtopping. The Hydraulics Laboratory, Hydromachinery Laboratory, and Outdoor laboratories at the Engineering Research Center are part of the unique research facilities at Colorado State University.

Acknowledgments Pacific Gas & Electric Co. provided funds under Cooperative Research< and Development Master Agreement (CRDA) No. Z-19-2-196-91. Under the CRDA, Reclamation and PG&E are performing cooperative research in association with Reclamation's Water Technology and Environmental Research (WATER) program and the Department of the Interior Dam Safety Program. Reclamation entered into a Cooperative Research and Development Agreement with the Electric Power Research Institute, CRDA No. 94-01, EPRI Agreement RP3752-0l. These CRDA's are under the authority of the Technology Transfer Act of 1986 (Public Law 99-502).

Mr. Kiran Adhya and Mr. Doug Morris have been instrumental during the establishment of these agreements, withstanding company reorganizations, Federal regulations and procedures. The authors recognize their contributions to the Dam Foundation Erosion study.

Key Words Foundation Erosion, Fall Velocity, Scour, Model, Pit 4, PG&E, 1994, Reclamation, Finances, Schedule

Dam Foundation Erosion Acknowledgments • vi

n 0 0 0 D D 0

J

Executive Summary The result of reevaluating the Probable Maximum Flood (PMF) of Reclamation or PG&E dams in many cases is recognition of insufficient spillway capacity for passing the flood volume. This creates a need to upgrade the spillway capacity, allow overtopping of the dam, or remove the dam. State and Federal Dam Safety regulations require reasonable evidence that an overtopping scheme will not result in destabilization of the dam due to erosion in the foundation and abutment areas. Current methods of predicting and evaluating erosion extents have limited applicability. Existing erosion prediction formulas do not track erosion as a function of time, and have limited application in hard-rock or cohesive foundation materials. This goal of this cooperative study is to improve technology for predicting and evaluating the progressive erosion extents in the foundation and abutment areas of a dam due to overtopping.

Since October, 1992, Reclamation and PG&E have been working to establish the Dam Foundation Erosion Study. This report presents a summary of all study activities from the study inception through the first quarter of 1995. Major accomplishments of the study to date include publishing a comprehensive Survey of Literature [9] and a Pre-Test Report [8], holding a Pre-Test Report seminar attended by more than 70 researchers, and dam safety officials, and establishing the remaining study agreements. Additionally, designs of the scale model and prototype models are complete, and the scale model is operational. Two series of tests are complete in the scale model facility. The first is the design and testing of the orifice. The orifice is necessary for simulation of a free-trajectory jet, like that of an overtopping dam. The second series of tests is the Pit 4 Dam Slab and Buttress Foundation Scale Model Simulation [10].

Reclamation received a Request For Proposal (RFP) in September, 1992, from Pacific Gas & Electric Co., for a cooperative research study of the Characteristics of Dam Foundation Erosion. In response to the RFP Reclamation invited PG&E, Colorado State University, and Dr. George Annandale to form a study team. The study team responded to the RFP in a joint proposal February 1, 1993. In this proposal the team proposed splitting the funding into thirds, Reclamation and the Department of the Interior Dam Safety program providing one-third, and the PG&E-EPRl Tailored Collaboration providing the other two-thirds. PG&E provided additional funds under the Master CRDA to Reclamation for a Survey of Literature and a Pre-Test Report.

On behalf of the study team, Reclamation entered into a Cooperative Research and Development Agreement with the Electric Power Research Institute, CRDA No. 94-01, EPRl Agreement RP3752-0l. This CRDA is the vehicle for receiving funds from PG&E and EPRl. Under the terms ofEPRl membership, member utilities pay a membership fee to EPRl that is a percentage of the retail power generation revenue of the utility. Twenty-five percent of the membership fee is set aside by EPRl for Tailored Collaboration (TC) agreements for research (Each party contributes 50%) that will benefit both EPRl and the utility. For the most part, the utility may simply direct EPRl to designate a portion of the TC funds for research projects of interest to the utility. EPRl matches the funds designated by the utility and performs the research or enters into an agreement with a third party, such as Reclamation, to perform the research.

This study is a collaboration of many agencies and programs in those agencies. Within Reclamation there are two sources of funding, the Department of the Interior Dam Safety program and the Water and Technology and Environmental Research (WATER) program. Funding sources outside of Reclamation include the Electric Power Research Institute (EPRl), Pacific Gas & Electric Co. (PG&E), and the Western Area Power Administration (Western). Colorado State University (CSU) is providing in-kind funding.

The total cost of this study is $1,125,000. There are five direct sources of funds for this study: 1) Department of the Interior Dam Safety, 2) Reclamation WATER, 3) PG&E, 4) Western, 5) EPRl. Reclamation is acting as the program manager for this study, receiving funds from the

Dam Foundation Erosion Executive Summary • vii

collaborating entitles and disbursing funds through this agreement. Of the total amount, Reclamation is funding roughly 37% through the Department of the Interior Dam Safety program, and roughly 7% through the Reclamation WATER, program, for total Reclamation funding of 43% of the total study cost. This represents significant leverage of Reclamation and PG&E funds by cooperating with other government agencies, private companies, and a state university.

The amount of the proposed Cooperative Agreement with Colorado State University is $853,200. Reclamation funds are split between the TSC organizations participating and this cooperative agreement. Reclamation funding makes up roughly 27% of the cooperative agreement amount. Non-Reclamation funding makes up the other 73% of the cooperative agreement amount. Reclamation funding only supports Reclamation staff.

In 1995 the following tasks will come to pass.

1. Cooperative Agreement between Colorado State University and Reclamation 2. Construction of Prototype model facility 3. Shakedown tests in prototype model facility 4. Clear water experiments in the Scale model 5. Clear water correlation Experiment 6. Temporal and Granular media experiments in Scale model 7. Interim reports 8. Publications 9. Year end report

The 1:3 scale model began operation in the spring of 1994 at the Hydraulics Laboratory, Engineering Research Center, Colorado State University. Plans of the facility are shown in the following figures. Features of the facility include the water supply system, 8 inch delivery pipe, orifice assembly, orifice, test basin, sediment trap, wasteway, platforms and stairs. One wall of the test basin is Plexiglas, facilitating viewing of the jet and test basin.

The design and specifications of the test basin for the Dam Foundation Erosion study are complete. A bid package is in preparation. The sub-contracting will begin as soon as funds are available from the Cooperative Agreement between Reclamation and Colorado State University. The effective date of the Cooperative Agreement is May 1995. The basin will be 15 feet deep, 30 feet wide and either 45 feet or 55 feet long. Both lengths will be options in the bid package. Colorado State law requires that bidders have 15 days to review the bid package. The Purchasing Department at Colorado State University anticipates that construction may begin within 45 days of the award and completion within 45 days of the notice to proceed.

Members of the Study Team are authoring numerous articles related to the Dam Foundation Erosion study. The following list shows the articles and publications planned through the first quarter of 1995.

American Society of Civil Engineers Journal of Hydraulic Engineering

1. Abt, S.R., Lewis, T.M., Wittler, R.J., Ruff, J.F., "Simulating Water Overtopping a Dam", Technical Note.

2. Wittler, R.J., Abt, S.R., Adhya, K., Lewis, T.M., "Pit 4 Simulations", Technical Note. 3. Wittler, R.J., Annandale, G.W., "An Algorithm for Estimating Progressive Extents of

Erosion in Dam Foundation Material", Journal Article.

United States Bureau of Reclamation

1. Wittler, R.J., et. Al., "Dam Foundation Erosion: Pre-Test Report", Final Report, US Bureau of Reclamation Water Resources Research Laboratory, December 1995.

2. Wittler, R.J., et. Al., "Dam Foundation Erosion Survey of Literature", Final Report, US Bureau of Reclamation Water Resources Research Laboratory, December, 1995.

Dam Foundation Erosion Executive Summary • viii

( "\

D D 0 D D 0 D D

1

3. Wittler, R.J., et. Al., "Pit 4 Dam Slab and Buttress Foundation Scale Model Simulation", Final Report, US Bureau of Reclamation Water Resources Research Laboratory, April, 1995.

4. Wittler, R.J., et. Al., "Dam Foundation Erosion 1994 Year End Summary Report", Final Report, US Bureau of Reclamation Water Resources Research Laboratory, April, 1995.

5. Wittler, R.J., et. Al., "Dam Foundation Erosion 1995 Year End Summary Report", Final Report, US Bureau of Reclamation Water Resources Research Laboratory, January, 1996.

Journal of Hydraulic Research

1. Annandale, G.W., "Erodibility". Journal of Hydraulic Research, May, 1995.

Appendix A contains the scope of work for the Cooperative Agreement between Reclamation and Colorado State University. The scope specifies the roles of the study team members, the type and number of experiments, the overall study schedule, numerical model development criteria, and the type and frequency of reports and meetings. Appendix B contains the overall study schedule in Gantt chart format.

Dam Foundation Erosion Executive Summary • ix

n C C [

C 0 D D

D D 0 D D D D D 0 0

. V \) V

Dam Foundation Erosion Study 1994 Year End Summary Report

0 o.

D D 0 0 0 D 0 0

Introduction

Since October, 1992, Reclamation and PG&E have been working to establish the Dam Foundation Erosion Study. This report presents a summary of all study activities from the study inception through the first quarter of 1995. Major accomplishments of the study to date include publishing a comprehensive Survey of Literature [9] and a Pre-Test Report [8], holding a Pre-Test Report seminar attended by more than 70 researchers, and dam safety officials, and establishing the remaining study agreements. Additionally, designs of the scale model and prototype models are complete, and the scale model is operational. Two series of tests are complete in the scale model facility. The first is the design and testing of the orifice. The orifice is necessary for simulation of a free-trajectory jet, like that of an overtopping dam. The second series of tests is the Pit 4 Dam Slab and Buttress Foundation Scale Model Simulation, described in the report of the same name [10].

The study suffered delays when both PG&E and Reclamation reorganized their business structures, and when PG&E withdrew from EPRI membership. The delays are past and the study is now progressing at the rate originally envisioned by the study team.

This report summarizes the study activities since the inception of the study, and presents the Study Team plan for the remainder of the study. Financial activity is documented as well as projected for the next three years of the study. A schedule for the final three years of the study is included as well as a comprehensive scope of work for the remaining tasks.

Study Background Reclamation received a Request For Proposal (RFP) in September, 1992, from Pacific Gas & Electric Co., for a cooperative research study of the Characteristics of Dam Foundation Erosion. In response to the RFP Reclamation invited PG&E, Colorado State University, and Dr. George Annandale to form a study team. The study team responded to the RFP in a joint proposal February 1, 1993. In this proposal the team proposed splitting the funding into thirds, Reclamation and the Department of the Interior Dam Safety program providing one-third, and the PG&E-EPRI Tailored Collaboration providing the other two-thirds. PG&E provided additional funds under the Master CRDA to Reclamation for a Survey of Literature and a Pre-Test Report.

Dam Foundation Erosion Study Introduction • 1

(\f\ " A. - /fl

n On behalf of the study team, Reclamation entered into a Cooperative Research and Development

0 Agreement with the Electric Power Research Institute, CRDA No. 94-01, EPRI Agreement RP3752-0l. This CRDA is the vehicle for receiving funds from PG&E and EPRI. Under the terms ofEPRI membership, member utilities pay a membership fee to EPRI that is a percentage of the retail power generation revenue of the utility. Twenty-five percent of the membership fee is set 0 aside by EPRI for Tailored Collaboration (TC) agreements for research (Each party contributes 50%) that will benefit both EPRI and the utility. For the most part, the utility may simply direct EPRI to designate a portion of the TC funds for research projects of interest to the utility. EPRI matches the funds designated by the utility and performs the research or enters into an agreement with a third party, such as Reclamation, to perform the research.

In 1994 EPRI and PG&E, under the auspices of a TC, funded the study in the amount of $210,000 or $105,000 each. PG&E withdrew from EPRI membership in 1995, abrogating the TC. However, PG&E is pledged to continue their portion of the funding in 1995 and 1996, at the rate D of $105,000 each year. Western Area Power Administration indicated their willingness to enter into a TC with EPRI in FY96 and FY97 at the rate of $50,000 per year, matched by EPRI for a two year total of $200,000. Thus EPRI was a funding partner in 1994, but will not be a funding partner until October 1995, when FY 96 begins. EPRI continues as a member of the study team. D

Quarterly Schedule of Activities: Q4 1992 - Q1 1995 The following table is a quarterly account of study activities from the fourth quarter of 1992 through the first quarter of 1995. Records of the events are the basis for the table compilation. The table does not reflect the daily communications and negotiations that have transpired as the study evolved. From December 1993, shortly after the Pre-Test Report seminar, until October 1994, PG&E and EPRI were in the process of establishing a Tailored Collaboration for the study. This delay prevented the initiation of the CRDA between Reclamation and EPRI and further the Cooperative Agreement between Reclamation and Colorado State University. Those agreements are now in place or nearly in place. A Cooperative Agreement between Reclamation and Colorado State University is in the final negotiation stages, a Requisition having been let by Reclamation.

Table 1. Quarterly activities of the Dam Foundation Erosion Study.

Quarter Activity

4th Qtr, 1992 Received Request for Proposal (~P) from PG&E on Characteristics of Dam Foundation Erosion.

1st Qtr, 1993 Responded to RFP from PG&E;

Formulated study team and new technology algorithm

Proposed study costs: $973,000 over three years

Received $12,000 from PG&E through Master Agreement (CRDA) No. Z-19-2-196-91 for Survey of Literature.

2nd Qtr, 1993 Received $78,200 from PG&E through Master Agreement (CRDA) No. Z-19-2-196-91 for Pre-Test Report and Scale Model design and construction.

Initiated Cooperative Agreement for scale model design and construction, prototype model design, and Pre-test Report between Reclamation and Colorado State University. Amount $78,200.

3rd Qtr, 1993 Prepared Pre-Test Report and held Pre-Test Report Seminar at PG&E headquarters . in San Francisco, Oct. 28, 1993.

4th Qtr, 1993 Completed design of scale model facility and began construction.

1st Qtr, 1994 Received $105,000 from PG&E through Master Agreement (CRDA) No. Z-19-2-196-91


Li

Table 1. Quarterly activities of the Dam Foundation Erosion Study (Continued).

Quarter Activity

2nd Qtr, 1994 Initiated Cooperative and Research Development Agreement (CRDA) between EPRI and Reclamation (EPRI Project No. RP3752-0l).

Began orifice design testing in scale model facility.

At the request of PG&E, changed scope of work in scale model facility for Pit 4 tests.

3rd Qtr, 1994 Completed orifice design

Completed design of prototype facility.

Completed Pit 4 tests.

4th Qtr, 1994 Initiated discussions with Western Area Power Administration (Western) to continue EPRI participation in FY96 & FY97, to replace funding after PG&E left,EPRI membership.

Initiated $10,000 bridging extension to . Cooperative Agreement with Colorado State University for scale model facility tests, making up for change in scope to Pit 4 tests.

Initiated three year, $853,200 Cooperative Agreement between Colorado State University and Reclamation. (In approval process at Reclamation. Expected implementation date April 1, 1995)

Established Department of the Interior Dam Safety funding levels at $145,000 per year in FY95-FY97.

Established Reclamation WATER funding at $40,000 in FY96 and $30,000 in FY97.

Received from Professor Steve Abt and Mr. Todd Lewis conceptual plan for ''Clear Water Experiments"and 'instrumentation Design': the first tasks in the scale model facility. Mr. Lewis is the graduate student in charge of the scale model facility. This plan was reviewed by Wittler and Annandale. Received Survey of Literature on 'Velocity Distributions in Plunge Pools" by Mr. Lewis and Professor Abt. These two papers form the nucleus of Mr. Lewis's thesis and will be published no earlier than June 1995 nor later than September 1995 .

1st Qtr, 1995 Began consultations with geoscience firms for Ground Penetrating Radar instrumentation for tracking erosion in near real-time.

Prepared proposal to National Science Foundation for instrumentation funding for Colorado State University. The instrumentation would support the Dam Foundation Erosion and Embankment Dam Breach studies.

Publications: 'Spillway and Foundation Erosion: Estimating Progressive Erosion Extents" for Water Power 95

"Spillway and Foundation Erosion: Erosion Threshold" for Water Power 95

'Design Flood Impacts on Evaluating Dam Failure Mechanics" for US-Korea Joint Seminar on the Reduction ofNatural Disaster in Water Environment

Seminars With Reclamation Dam Safety staff on Overtopping Research, Dam Foundation Erosion, and Embankment Dam Breach in Denver, Jan. 17, 1995

With BC-Hydro on Overtopping Research, Dam Foundation Erosion, and Embankment Dam Breach in Denver, Jan. 24, 1995


[

[

n n n D D []

D 0 D 0 D 0 0 Li Li

Finances

This study is a collaboration of many agencies and programs in those agencies. Within Reclamation there are two sources of funding, the Department of the Interior Dam Safety program and the Water and Technology and Environmental Research (WATER) program. Funding sources outside of Reclamation include the Electric Power Research Institute (EPRI), Pacific Gas & Electric Co. (PG&E), and the Western Area Power Administration (Western). Colorado State University (CSU) is providing in-kind funding.

The total cost of this study is $1,095,000. The amount of the proposed cooperative agreement with Colorado State University is $853,200. There are five direct sources of funds for this study: 1) Department of the Interior Dam Safety, 2) Reclamation WATER, 3) PG&E, 4) Western, 5) EPRI. The following paragraphs track the inception of the study and the evolution of the financing plan.

Reclamation and Pacific Gas & Electric Company entered into Cooperative Research and Development Master Agreement (CRDA) No. Z-19-2-196-91 in December 1991. Under the CRDA, Reclamation and PG&E will perform cooperative research in association with Reclamation's Water Technology and Environmental Research program. On behalf of the study team, Reclamation entered into a Cooperative Research and Development Agreement with the Electric Power Research Institute, CRDA No. 94-01, EPRI Agreement RP3752-0l. This CRDA is the vehicle for receiving funds from PG&E and EPRI. These agreements are under the authority of the Technology Transfer Act of 1986 (Public Law 99-502).

Table 2 shows the sources and lists the years that funds are scheduled for receipt. Reclamation is acting as the program manager, receiving funds from the collaborating entities and disbursing funds through cooperative agreements and other contracts. Reclamation is funding roughly 37% through the Department of the Interior Dam Safety program, roughly 7% through the Reclamation WATER, program, or total Reclamation funding of 4 3 % of the total study cost. This represents significant leverage of Reclamation, EPRI, and PG&E funds by cooperating with other govermnent agencies, private companies, and a state university.

Roles of Collaborating Entities Within Reclamation there are four groups collaborating on the study including the Dam Safety Management office, the Research Programs office, the Water Resources Research Laboratory, and

Dam Foundation Erosion Study Finances • 5

n Geotechnical Engineering Group 4. Outside of Reclamation, EPRI, PG&E, Western, and 0 Colorado State University are collaborators. This section discusses the planned roles for each of these entities during the study. The roles relate to the financial, programmatic, and technical activities planned for each entity. D

Reclamation - TSC Water Resources Research Laboratory, 0-8560

Engineers and Technicians from the Water Resources Research Laboratory will provide program management, technical contributions, technical advice, and technical review for the study. Dr. o Rodney Wittler is the Study Team Leader and Principal Investigator. Mr. Brent Mefford is the Technical Specialist and Peer Reviewer for the study. Mr. Philip H. Burgi is the Group Manager.

Reclamation - TSC Geotechnical Group 4, 0-8314 0 Personnel of Geotechnical Group 4 will assist by providing geotechnical engineering advice and review. Mr. Bill Engemoen is the Group Manager, Mr. Greg Scott, Mr. Chuck Redlinger, and Mr. Joe Kottenstette are geotechnical engineers, consulting on the study.

Reclamation - Dam Safety Management Office, 0-6600

The Dam Safety Management Office·is providing thirty-seven percent of the funding for the study. Reclamation Dam Safety staff will review the technological advancements that result from the study and encourage appropriate application of the technology. They will assist the study team leader with program management. [

Reclamation - Research Programs Office, 0-6700

PG&E

EPRI

The Research Programs Office is providing six percent of the funding for the study. Research Programs office staff will review the technological advancements that result from the study and will recommend means for publishing those results according to provisions 'of the Technology Transfer Act. This office will also provide assistance with program management.

Pacific Gas & Electric Co. is providing twenty-nine percent of the funding for this study. Mr. Ron Adhya will provide engineering assistance, technical review, and program management assistance to the study team. PG&E is also making their records available for evaluating the operational problems related to this study of dams owned by PG&E.

The Electric Power Research Institute is providing nineteen percent of the funding for this study. Mr. Doug Morris is the EPRI Project Manager for CRDA 94-01, EPRI Agreement RP3752-0l. As such he will provide program management assistance to the study team. He will also serve as a technical reviewer and assist in the determination of how to disseminate the results of the study.

Western

Western Area Power Administration is providing nine percent of the funding for this study. Reclamation will act as program managers in the interest of Western. Western personnel will also have the opportunity to provide technical review for the project.

Colorado State University

Colorado State University is providing roughly $109,000 of in-kind contributions to the study through overhead waivers as participants in the study. Researchers in the Department of Civil Engineering will conduct laboratory studies, as outlined in the scope of work, and will participate in publishing the results of the study. Professor James Ruff will be the Principal Investigator and Professor Steven Abt will be the Co-Principal Investigator. Their staff of Research Scientists and Graduate Research Assistants and undergraduate students will perform the laboratory studies.


J

Summary Reclamation is acting as the program manager for this study, recervmg funds from the collaborating entities and disbursing funds through this agreement. The total cost of the study is $1,095,000. Of this amount, Reclamation is funding roughly 37% through the Department of the Interior Dam Safety program, and roughly 7% through the Reclamation WATER program, for total Reclamation funding of 43% of the total study cost. This represents significant leverage of Reclamation and PG&E funds by cooperating with other government agencies, private companies, and a state university.

The amount of the proposed Cooperative Agreement with Colorado State University is $853,200. Reclamation funds are split between the TSC organizations participating and this cooperative agreement. Reclamation funding makes up roughly 27% of the cooperative agreement amount. Outside funding makes up the other 73% of the cooperative agreement amount. Reclamation funding only will support Reclamation staff.

Funding Summary Table 2 is a comprehensive tabulation of funding for the Dam Foundation Erosion study. Funding activities occur in five fiscal years, FY93-FY97. The amounts shown in FY93 and FY94 are estimates. In FY95 Reclamation increased levels of funding from the Dam Safety program. In addition, Dam Safety moneys have financed the delay in the startup of the testing phase of the study. No funds from EPRI, PG&E, or Western have been used for program management, contracting, or interim activities. The delay in implementing the testing phase of the study is due to reorganizations at PG&E, EPRI, and Reclamation. Reclamation Dam Safety and Western have partially made up a funding shortfall that occurred when EPRI ceased to be a study team member following the withdrawal of PG&E from EPRI membership .

Table 2. Funding summary.

Funding FY93 FY94 FY95 FY96 FY97 Total DOI-Dam Safety $30,000 $80,000 $145,000 $145,000 $145,000 $545,000

Reclamation-WATER $20,000 $20,000 $40,000 $30,000 $110,000 EPRI/Reclamation TC $100,000 $100,000 $200,0002

Western1 $50,000 $50,000 EPRI $50,000 $50,000

PG&ECRDA $90,200 $105,000 $105,000 $300,200 EPRI/PG&E TC $210,000 $210,000

EPRI $105,000 PG&E $105,000 Total $140,200 $205,000 $355,000 $390,000 $275,000 $1,365,200

Expense Summary Table 3 is a comprehensive tabulation of the costs, start, and finish dates of tasks to date and remaining tasks. The attached scope of work outlines the remaining tasks . Moneys received but not disbursed remain in trust accounts with Reclamation. A three year cooperative agreement

1 A tentative agreement by Western to support research.

2 Beginning in 1995 EPRI is charging 11 % overhead and administrative costs to all Tailored Collaborations. This will reduce this amount by roughly $20,000 and likewise the study total.


between Reclamation and Colorado State University commits those funds to complete the remaining tasks. As of this date, the total cost for the remainder of the study is roughly $1,125,000. The funding commitment of PG&E has not been altered.

Table 3. Itemized cost summary from inception to projected end of the study.

Task Start Finish Cost Proposal and revisions December 1992 February 1, 1993 NIA Survey of Literature February, 1993 August, 1993 $12,000 (PG&E)3 Pre-Test Report, Model Designs, Pre- June, 1993 October 1993 $78,200 (PG&E) Test Report Seminar, Pit 4 tests in scale model Contracting, Program Management October 1993 January 1995 $150,000 (USBR)

Subtotal $240,200

Instrumentation Design and Clear September 1994 January 1995 $10,000 (Reclamation) Water Experiment Design Remainder of Scope of Work April 1995 December 1997 $315,000 (PG&E) Note: The scope of work is included in $495,000 (USBR)

$205,000 (EPRI) $100,000 (Western)

Subtotal $1,125,000

Total $1,365,200

3 The source of the funds is indicated in parenthesis.


n 0 0 n D 0

J

J u u J

J

Schedule

Schedule Appendix B contains the schedule, in Gantt chart form, for all remaining study tasks. Table 4 lists the tasks that make up the Gantt chart in Appendix B.

Table 4. Task list for remainder of Dam Foundation Erosion study.

Task Duration Start Finish Subcontracting 60d 4/1/95 6/23/95 Physical Modeling 680d 4/1/95 11/7/97

1:3 Scale Model 195d 4/1/95 12/29/95 Construction 5d 4/1/95 4/7/95 Instrumentation Design 20d 6/26/95 7/21/95 Clear Water Experiments 20d 7/24/95 8/18/95 · Interim Report 10d 8/7/95 8/18/95 Temporal Experiments 30d 8/21/95 9/29/95 Granular Material Experiments 30d 10/2/95 11/10/95 Selected Material Experiments Od 11/10/95 11/10/95 Final Report/Thesis 35d 11/13/95 12/29/95

1: 1 Prototype Model 637d 6/1/95 11/7/97 Construction 100d 6/1/95 10/18/95 Shakedown & Instrumentation Experiments 12d 10/19/95 11/3/95 Clear Water Correlation Experiments 20d 11/6/95 12/1/95 Granular Material Correlation Experiment 20d 12/4/95 12/29/95 Interim Report 20d 4/1/96 4/26/96 Cubical Elements Experiment 30d 3/1/96 4/11/96 Vertically Oriented Slab Experiment 30d 4/12/96 5/23/96 Upstream Oriented Slab Experiment 30d 5/24/96 7/4/96 Downstream Oriented Slab Experiment 30d 7/5/96 8/15/96 Interim Report 20d 11/29/96 12/26/96 Cohesive Material Experiment (Optional) 30d 3/1/97 4/11/97 Cohesive Material in Slab Joints (0 tional) 30d 4/14/97 5/23/97

Dam Foundation Erosion Study Schedule • 9

Table 4. Task list for remainder of Dam Foundation Erosion study (Continued).

Task Duration Start Finish 1: 1 Prototype Model (Continued)

Granular Material in Slab Joints {Optional) 30d 5/26/97 7/4/97 Other Experiments as Resources Allow Od 7/4/97 7/4/97 Final Report/Dissertation or Thesis 90d 7/7/97 11/7/97

Numerical Model Development 636d 6/26/95 12/1/97 Specifications JOd 6/26/95 7/21/95 Analysis 20d 7/24/95 8/18/95 Flow Charting 20d 8/21/95 9/15/95 Prototyping Phase 1 120d 9/18/95 3/1/96 Prototyping Phase 2 120d 4/1/96 9/13/96 Alpha Testing 30d 7/1/97 8/11/97 Beta Testing 40d 8/12/97 10/6/97 User Manual 120d 5/6/97 10/20/97 Version 1.0 20d 11/4/97 12/1/97

Final Report Compilation, Review, and Issue 65d 12/2/97 3/2/98 Compilation 20d 12/2/97 12/29/97 Review 40d 12/30/97 2/23/98 Issue 5d 2/24/98 3/2/98

Calendar 1995 Tasks In 1995 the following tasks will come to pass .

1. Completion of Cooperative Agreement between Colorado State University and Reclamation

2. Construction of Prototype model facility

3. Shakedown tests in prototype model facility

4. Clear water experiments in the Scale model

5. Clear water correlation Experiment

6. Temporal and Granular media experiments in Scale model

7. Interim reports

8. Publications

9. 1995 Year end report

The Study Team will decide upon the content and types of interim reports and publications in consultation with PG&E, EPRI, Western, and the Department of the Interior Dam Safety Program.

Dam Foundation Erosion Study Schedule • 1 O

D D D D D 0

D D

u

Prototype Model Design

The design and specifications of the test basin for the Dam Foundation Erosion study are complete. A bid package is in preparation. The sub-contracting will begin as soon as funds are available from the Cooperative Agreement between Reclamation and Colorado State University. The effective date of the Cooperative Agreement is May 1995. The basin will be 15 feet deep; ·30 feet wide and either 45 feet or 55 feet long. Both lengths will be options in the bid package. Colorado State law requires that bidders have 15 days to review the bid package. The Purchasing Department at Colorado State University anticipates that construction may begin within 45 days of the award and completion within 45 days of the notice to proceed.

Prototype Plans Figure 1 through Figure 9 show the design drawings of the prototype facility. The design continues to be updated as information from the scale model becomes available.

P\JMPBACK SYSTEM

2:1 SLOPE OVERTOPPNG FACILITY

NEW 3" DIA/"ETER FEEDER PPELltt

3 FT DIAMETER SIJ'PL Y PIPELNE FROM HORSETOOTH RESERVOIR

DAM FOI.N)ATION

EROSION FACILITY

WASTEWAY

Figure 1. Overall plan view of Dam Foundation Erosion facility in relation to existing overtopping research facility at Colorado State University.

Dam Foundation Erosion Study Prototype Model Design • 11

Dam Foundation Erosion Study

REDWOOD FLOOR[NG

L 5 X 5 X 3/4

DI/\ 3"-6··

DIA 2·-0··

s·-o·

CHAN\JEL FOR INSTRUMENTATION

1-----------sa--o··-------------

r-o·

3"-o··

FRAMEWORK W 8 X 35 TYP

l 32'-o··

36"-0"

10·-o·

TRUSS L ,----L'----'.J..__u.._ _____________ ~ _ _._2+·-8_-~

L 2 X 2 1/8 TYP

TITLE: T AILBOX ASSEMBLY

Figure 2. Plan, side, & front view of prototype facility.

BAO<FLL

EXISTING TAILBOX

Prototype Model Design • 12

CJ CJ

48.0'

·= l-47.o'

12.0::-~ - rE rH i : / JI

F

1 I Jo 2.0'

TYP

/ 17.0

L D /

CHA""-EL FOR STOP B...OCKS 4 PLACES

_j

D

~ ----36~--CHAr-NcL FCF

INSTRIJl'c:Nf.AT ICN

L A

(~ ' \

' /

' I ' '

I

I ' I

/

I ' I "'-.· II ) I ( J -~ - - - - - - - _/ -

~ VIEW C-C TITLE, TAILBOX. STR\...CTLRE 0::TAIL DA TE 11/16/94 . PAGE I OF 5

· Figure 3. Test basin structure detail, prototype facility. Plan view.

------------sa·. ~0------------------i-----------------s, -o·----------------+1

rE

IT· o·

3<1·- o·

CHA<NcL ·fCR INSTRU<ENT A TION

L D

L A

TITLE, TAILBOX. STR\..CTI.FE CETAIL DATE 4/.4/95 PAGE I CF 6 IEXTENJ:0 80Xl

•? VERTICAL BARS

•3 VERTICAL BARS

•3 HCRIZONT AL BARS

32.0'

F

1

. CH""-"EL FOR STOP B..OCKS 4 PLACES

_j

D

_j

A

V[EW 8-B

Figure 4. Test basin structure detail, prototype facility extended box option.


6.0"X 12.0"SPAC!r-.G [[J\ITIN.Ja.JS IN 2· SECTl[J\I 2 PLACES

_/ WALL

I

11111111 IHI

11111111 IIIIIJ.>

TITLE: TAILBOX. Sffil..CTURE CETAIL DA TE: 9/ 26/ 94 PAGE 2 CF 5

I I I I

II I I I II I I I ii I I I I I I I I II I

I I Ill I I I l l I I

VIEW A-A

I I I I I l I I I I I I

1 r~$~ 12.0 " X 12.0"SPAC lr-.G C[J\ITIN:...0.JS IN I' WALL SEC Ti(J\I AS SI-OWN

-

,

-f-2.0

1s.o·

f B.o·

• 3 BAR 12.0- VER TIC AL SPAC!r-.G TYPICAL

~38-"R6 .0·· f-CRIZD-JT AL SPACN, TYPICAL

Figure 5. View A-A, rebar plans.

6' - 3"

~-t-titil,!i:i:i::;;:=:;:::;=;::;:::;!:l.=;;=;,::;=:;==::;;=;!:!=::;:::;::;=::;;=;!:!=::;=;::;,.;---i- rr-r-o 2· - O"

~~=====~~~=~=~=~==1._J_ r - O"

----T - 3"----6' - 3"

VIEW C-C TYPICAL

2· - O"

l__~~~==~~

TITLE: TAILBOX. STRUCT\FE [£TAIL DATE : 4 / 4 / 95 PAGE 3 CF 6


Figure 6. Views B-B and C-C.

~---T - 3"----.i

VIEW B-B TYPICAL


0 D

0 D 0

2·-0·

CHANt-.EL FOR INSTR\Jl"ENTATION

RLBEER WATER STOP ALL AR(lJI\O

5'-0" s·-o ..

I 1/4''

V[EW G-G

S'-0" CHAf\NEL Fffi INSTRUMENTATION 4 PLACES

FLOOR SLOPES TO SOUTH 1:800

t i;:::'.;"11 :=-===:~--ljl------ljl-----lp''---------1.'-;::;====!t'i

ho·

SECTION E-E

•5 BAR 6"5PACirs1J TYPICAL

SECTION 0-0

r-~

T[TLE: TAILBOX. STR\JCTLRE DETAIL DA TE: 4/ 4/95 PAGE 4 CF 6

SLAB DETAL

3· - O"

-----s·- 3"

------------7' -3"

Figure 7. Sections E-E, D-D, and slab detail.

CHANNEL FOR

1-----is·-o .. -----~1

STOP BLOCKS ~ 4 PLACES I ~ rs·-o"TS'-0"~

I I s·-o

i

t 4'-0

.-------'--------~~~~~~~-------'----'--, __l I I TITLE: T AILBOX. STRUCTURE DETAIL DATE: 4/ 4 / 95 PAGE 5 OF 6

2'-0" :: 3 PLACES

VIEW F-F

--::r-----..-- 3 '-0" 4 PLACES

Figure 8. View F-F.


30"

3" a··-i--a··Ta··1 3.0

I I

12"

l

.75"D1A STUD 1/L 4 PLACES

i

#5 BAR

L 4 PLACES

A

·1

r--6"

• t 6"

•

I _j

4X 24··

A

Figure 9. Plate detail.

I

L6 .. 1s··

SECTlON A-A

T[TLE: PLATE. BASE DATE: 4/4/95

I

--30"----e;,.i 3 .. -j,,l,a-t;e-,..e.- 8 .. ---- 8 .. --el---- 8 ..

3··

12"

18"

l TITLE: PLATE. FOOTING DA TE:4/ 4/95


t"X 2"'SLOT 4 PLACES

Figure 10. Footing detail.


a

D

Features of Prototype Design Plans are for construction of the prototype facility at the Outdoor Laboratories, Engineering Research Center, Colorado State University. The Engineering Research Center is part of the Foothills campus of Colorado State University, located just west of Fort Collins, Colorado. Fort Collins is roughly 65 miles north of Denver, Colorado.

The water supply for the outdoor laboratory facilities is Horsetooth reservoir. Horsetooth is a Reclamation reservoir, part of the Colorado Big Thompson project. Seasonal irrigation causes the reservoir elevation to fluctuate, resulting in a significant fluctuation in the discharge available from the reservoir to outdoor laboratories.

The laboratories water supply is the 36 inch Horsetooth supply pipeline. This pipeline runs along the ridge of the hogback that forms the eastern boundary of the outdoor laboratories. The ridge hogback is roughly 75 feet above the surrounding area. Other facilities at the outdoor laboratories include the Rainfall Runoff facility, Watershed Simulation facility, Bridge Pier Scour facility, Hydromachinery laboratory and Turbine Test facility, Culvert Scour facility, Blast Induced Liquefaction facility, River Mechanics facility, and the recently completed Overtopping facility.

Reclamation, Colorado State University (CSU), and the Electric Power Research Institute (EPRl) have an ongoing cooperative research effort to determine low-cost, feasible methods for providing overtopping protection for embankment dams. Investigations include tests of an overlapping tapered concrete. block shape installed over gravel filter material in the Overtopping facility. The stability of the overlapping tapered block system has been confirmed by the large scale tests.

The Overtopping facility is near-prototype size, with a height of 15.24 m (50 ft). Figure 11 is an overall plan of the Overtopping facility, showing the concrete headbox, chute, tailbox, and pump sump. Figure 12 shows the concrete chute on a 2: 1 (H:V) slope, with a maximum width of 3 m (10 ft). Partitioning the chute provides a flexible width capability. Recirculating the flow with the pump back system increases the total discharge through the facility. To date, the maximum unit discharge in the facility is 2.94 m3/m/s (31.6 ft3/ft/s) or a total discharge of 14.7 m3/m/s (158 ft3/ft/s). A sonic flow meter measures the discharge with accuracy of 1.5%.

SETOOTH SLPPl y PIPELll'E

~t1'BACK SYSTEM

Figure 11. Plan view of Overtopping facility.


T AILBOX

I~

WASTEWA TUBES


FHCFILE. 2:1 OVERTCPP[Nj F ACD...ITY 1-1r94 RFR,&,P

Figure 12. Profile of Overtopping facility.

lM..WA'fER REG..l./\Tt-G GATES

WAS1EWAY llJlES

The Dam Foundation Erosion (DFE) prototype facility will be adjacent to the Overtopping facility, sharing the tailbox and wasteway of the Overtopping facility. A new feeder pipeline will tee off of the Horsetooth supply pipeline, feeding the DFE prototype facility. New butterfly valves, one on the feeder pipeline and one downstream of the tee on the Horsetooth supply pipeline, will isolate the two facilities from each other while operating. The feeder pipeline descends from the hogback ridge along the slope of the hogback at a slope of roughly 2:1.

After descending roughly 35 feet, the feeder line joins the. orifice supply pipeline. The orifice supply pipeline is level, extending out from the hogback slope to the superstructure above the test basin. The diameter of the orifice supply pipeline is 24 inches. The superstructure supports the orifice assembly. Plans for the orifice assembly are shown, scaled 1 :3, in the Scale Model Design section. All parts of the prototype facility orifice assembly are exactly 3 times larger than the parts shown in the scale model design section.

Figure 14 shows the 1:3 scale dimensions of the test basin and orifice and orifice delive_ry pipe. The 24 inch orifice supply pipe and manifold along with a 42 inch pipe section and orifice assembly form an annulus. The annulus assembly is 11 feet (3.35 m) wide. All piping is Schedule 40. 13 shows the downstream aspects of the facility including stop logs that control tail water level, stairs and upper viewing platform, and the relative position of the 24 inch orifice supply pipeline.

Figure 16 shows a 1:3 scale profile of the test basin. Water enters through the 24 inch orifice supply pipeline via the manifold, shovm in Figure 21, into the 42 inch pipe section. The flow direction through the manifold is towards the head wall of the test basin. The water flows over and under the manifold section, towards the orifice on the downstream facing side wall of the 42 inch pipe section. Figure 17 details the orifice assembly in the 42 inch pipe section. The orifice ,'lidth is 10 feet inches (3.05 m). The entire assembly and 24 inch orifice supply pipeline rotate about the pin in the end of the assembly. The Dresser coupling allows full rotation of the orifice assembly.

Figure 18 is a 1:3 scale front view of the orifice through the side wall of the 42 inch pipe section. The orifice height is adjustable from 1.2 to 8.4 inches (30-213 cm). The orifice has standard weir knife edges. Figure 21 shows the manifold pattern, developed flat. More than 18 variations of the manifold pattern were tested in the Orifice Design phase of the Dam Foundation Erosion study. The objective of that phase of design was a uniform, coherent jet, issuing perpendicular to the 24


0 0 0 D

inch orifice supply pipeline and parallel to the axis of the test basin. Head taps installed at the quarter points of the annulus orifice assembly measure the head distribution in the exterior portion of the annulus, the driving head for the flow through the orifice. A constant head distribution causes a uniform flow distribution across the width of the orifice.

Figure 19 shows a 1:3 scale half of the orifice section, Section A-A from Figure 18. A fastener holds the orifice plate and holding plate to the wall of the 42 inch pipe section. Figure 20 shows annulus Section B-B, from Figure 17. Flow enters the interior of the annulus section axially through the 24 inch orifice supply pipeline. The flow passes through the manifold, perpendicular to the axis of the 24 inch orifice supply pipeline. The manifold pattern causes an even distribution of flow and pressure in the exterior of the annulus section. Flow splits into two streams, one flowing over the manifold section and another flowing beneath the manifold section. The two streams meet just upstream of the orifice and exit through the orifice. The orifice assembly may rotate about the axis of the 24 inch orifice supply pipeline so that flow may issue at any vertical angle with respect to the test basin.

The DFE prototype facility shares the tailbox of the Overtopping facility. The tail wall of the prototype test basin is the side wall of the Overtopping tailbox. Stop logs will contain the test material and regulate the tailwater in the prototype test basin as Figure 4 shows. After cascading over the stop logs, flow exits the prototype test basin though holes bored in the side wall of the Overtopping facility tailbox. This arrangement provides means for recovering and reusing materials from both facilities.

Figure 2 shows the redwood flooring on the viewing platform directly behind the orifice assembly. This platform facilitates viewing from behind the jet and from above the test basin. Another viewing area is available on the slope of the hogback, along the east side of the test basin. A carriage may be installed to traverse the basin for instrumentation and some viewing opportunities.

A subcontractor (to Colorado State University) will construct the test basin. Staff of the Engineering Research Center Shops will construct the piping modifications, orifice assembly and superstructure, and related components. The . shops staff will also be in charge of placing and removing test material from the test basin.


0 .

C . [~

D

0 D D D D D D 0

Scale Model Design

Facility Plans The 1:3 scale model began operation in the spring of 1994 at the Hydraulics Laboratory, Engineering Research Center, Colorado State University. Plans of the facility are shown in the following figures . Features of the facility include the water supply system, 8 inch delivery pipe, orifice assembly, orifice, test basin, sediment trap, wasteway, platforms and stairs. One wall of the test basin is Plexiglas, facilitating viewing of the jet and test basin.

VALVE

18·,15· ORIFICE PLATE s· DELIVERY PPE

/UPPER PLATFORM

14· DIA PPE / TEST BASIN

____ .__.._._.,__......__,

00_,_ __ ........ ,_ _______ 1- WALKWAY Q~

ORFICE

/3/4" ACRYLIC PLASTIC

io-------14· 3·-----~ 1------1z o·· ____ _, 4 ' 4 · io-------13" 4·-------

Figure 13. Area plan of 1:3 scale model facility with walkways, platform, stairs, test basin, and orifice.

Darn Foundation Erosion Study Scale Model Design • 21

0

()

o::'.)

n

1 3· 4"----i ;-8" DIA DELIVERY PIPE

R_OW CfKlD\J '-(14· DIA PIPE ~

~ORIFICE

/ TEST BASIN

-~

12· O"

13 4 ..

Figure 14. Detailed plan of basin and orifice.

- !:::=== =======± = I

Figure 15. Elevation of 1:3 facility from wasteway (downstream) perspective.

Dam Foundation Erosion Study Scale Model Design • 22

1

0

o· 4·

1· DIA. PIN

~8· DELIVERY PIPE

--3· 4"-~-14" PIPE

/PLEXIGLAS SIDE

I

~: ------12· 0"------

~--------------13' 4"-------------

,E-~

5 D

Figure 16. Side elevation of basin with orifice.

4· o· 3· 8"

- 3· 4· ·1

I

I

l Q 0

j

\_ 14 - DIA. PIPE 3;4·· END PLATE FLANGE_/ " 1/2 END PLATE

ORIFICE DISCHARGE PIPE

Figure 17. Orifice discharge pipe.

DRILL AND TAP 12 EA. 3/4" - 10 - UNC HOLES AND PROVIDE GASKET.


(\ .

-----3' 8"------:::,,1 TOP HOLD DOWN PLATE ADJJSTABLE ORIFICE PLATE ~

o· T~ \ 1A

5/ 16" STUD 1.25· LONG

7 / 16" DIA. OLE IN TOP HOLD DOWN PL ATE

1/2" X 1.6· SL OT IN ORIFICE PLATE

ORIFICE PL ATE DETAIL

Figure 18. Orifice plate detail.

CROSS SECTION A

la.. A

CLEAN SHARP CORNER

Figure 19. Cross section A-A. Detail of orifice blades. (Upper half only)


n D D 0 0 n D

u

r ADJUST ABLE I ORIFICE PLATE

0 <.O

TOTAL RANGE OF OPENING FROM 0.4· TO 2.8·

~ HOLD DOWN PLATE

"\_ 14" ORIFICE PIPE

8" DELIVERY PIPE MANIFOLD

SEC TI ON B Figure 20. Cross section B-B. Detail of inner and outer piping configuration. Flow enters through the inner pipe/manifold into the outer pipe.

- - -----------48"--------------

FLOW

4 o 2.8" X 3.625"

4 " 6.125" X 3.625"

2 o 5· X 3.625"

4 " 3_9375· X 3.625"

6 o 1.175· X 3.625.

>

2 " 6.125" X 3.625"

2 " 3_9375· X · 3.625.

2 " 1.75· X 2.8125"

I PIPE CIRCUMFERENCE DEVELOPED FLAT. ORIGINAL AREA • 391 in"2 NEW AREA • 400 in"2

8" MANIFOLD OUTLET PATTERN

Figure 21. 8" Manifold outlet pattern.

I C 0.5 C


/I !\

Orifice Design & Testing Between April and July, 1994, the Scale Model Study Team designed and tested the orifice and manifold assembly in the scale model facility. The following paragraphs are brief accounts of the results of eighteen tests performed during the test series.

Test No. 1 (4/14/94): This was the initial manifold/diffuser system design. The diffuser used a hole pattern in a tria:ngular shape (large end upstream) with 265 in2 of open hole area. The orifice blades on the manifold were set at a uniform 1.6-in opening. The resulting jet was skewed significantly toward the west wall of the test facility (upstream) and was observed to be extremely non-uniform.

Test No. 2 (5/3/94): For this test, the diffuser hole pattern was widened to 374 in2 of open surface area. This had the effect of reducing the jet skewness toward the upstream wall. However, the non-uniformity of the jet was not affected.

Test No. 3 (5/5/94): The diffuser pattern was opened further (391 in2). No noticeable changes

were observed.

Test No. 4 (5/6/94): The diffuser pattern was opened again (396 in2). The jet skewness was reduced slightly and the jet became more uniform (but not by a significant amount).

Demonstration (5/16/94): For this site visitation, the diffuser pattern was opened more ( 401 in2). The orifice blades on the manifold were closed by 0.1 in such that the opening was a uniform 1.5 in. There was no observable change in the uniformity of the jet and skewness was seen to increase.

Test No. 5 (5/17/94): The diffuser pattern was closed to a different configuration (391 in2). This had the effect of decreasing the skewness of the jet and increasing the non-uniformity of the jet.

Test No. 6 (5/18/94): The orifice blades on the manifold were closed to a uniform 1.4 in. There were no discernible changes in the properties of the jet, but the available outlet pressure changed from 2 LB/in2 to 3 LB/in2

.

Test No. 7 (5/19/94): The orifice blades on the manifold were closed further to a uniform 1.3 in. This had no observable effect on the jet system.

Test No. 8 (5/23/94): The diffuser pattern was opened up (400 in2). Jet skewness increased and the uniformity of the jet improved.

Test No. 9 (5/24/94): The diffuser pattern was changed, but the same surface area as Test No. 8 was kept. The orifice blades were opened to a uniform 1.4 in. This had no discernible change in the jet.

Test No. 10 (5/25/94): The orifice opening was changed to a trapezoidal configuration (1.4 in on the downstream end and 1.2 in on the upstream end). This didn't effect the jet appreciably.

Test No. 11 (5/27/94): The diffuser pattern was closed to a different configuration (386 in2). This was done to try to recreate Test No. 4 so that the early portion of testing could be compared with the later testing to decide which diffuser configuration to further develop. Unfortunately, there was no discernible difference between this test and test No. 10.

Test No. 12 (6/1/94): The diffuser pattern was changed, but kept the same open hole area (386 in2

) . The orifice blades on the manifold were closed to a uniform 1.2 in. Again, there were no discernible changes between this test and the last.

Test No. 13 (6/6/94): The diffuser pattern for this test was reversed end-to-end (same pattern as Test No. 12). The orifice blades on the manifold were also opened to a uniform 1.6 in. This had the effect of increasing the skewness of the jet and making the jet less uniform.


D D n D 0 n [ J

u

J

D

Test No. 14 (6/8/94): The pattern used in Test No. 12 was replicated, but this time pressure taps were installed on quarter-lengths on the back side of the manifold. The jet remained the same as in Test No. 12, but this time, an idea of the pressure distribution inside the manifold was gained. The downstream tap read 7.68 ft (H20), the middle tap read 6.87 ft (H20), and the upstream tap read 4.53 ft (H20). Further testing will try to refine this pressure distribution so that it is uniform.

Test No. 15 (6/24/94): After researching the topic of pressure manifold design, manifold theory was applied via an iterative technique to redesign the diffuser pattern. The end result was a much more uniform pattern with 398 in2 of surface area. This straightened the jet more and had a profound positive impact on the jets uniformity. The downstream pressure tap read 7.45 ft (H20), the middle tap read 6.875 ft (H20), and the upstream tap read 4.968 ft (H20).

Test No. 16 (6/30/04): The diffuser pattern was closed somewhat on the upstream end (363 .5 in2). This increased the skewness of the jet. The downstream pressure tap read 7.205 ft (H20), the middle tap read 6.455 ft (H20), and the upstream tap read 4.058 ft (H20).

Test No. 17 (7/6/94): The diffuser pattern was closed further on the upstream end (325.9 in2). This further increased the skewness of the jet and made the jet less uniform. The downstream pressure tap read 7 .965 ft (H20), the middle tap read 7 .175 ft (H20), and the upstream tap read 4.508 ft (H20).

Test No. 18 (7/19/94): The diffuser pattern was returned to the Test No. 15 condition and a 0.5-in "orifice rib" was placed in the diffuser one-third of the length of the manifold downstream from the upstream end. This had a dramatic effect on the pressure distribution inside the manifold. the downstream pressure tap read 6.115 ft (H20), the middle tap ready 5.435 ft (H20), and the upstream tap read 5.228 ft (H20). The uniformity of the jet was noticeably improved, in fact, it now appears almost completely uniform. However, there is still a slight upstream skew to the jet.

Table 5 is a summary of the orifice design tests in the scale model facility. The table includes the test number, test date, discharge, diffuser angle, diffuser hole area, orifice blade opening and setting, pressure in the supply pipeline, and head tap readings. Then the table has three subjective ratings of jet uniformity, skewness, and finally, a ranking. The subjectivity comes from the judgment of the Principal Investigator, Scale Model Study Team Leader, and study consultants who witnessed all of the tests. The ranking quantifies the relative performance of each configuration and generally improved as the testing progressed.


Table 5. Summary of orifice design tests in the Scale Model facility.

Test Test Maximum Diffuser Diffuser Hole Orifice Blade Orifice Upstream Right Tap Mid Tap Left Tap Jet Jet Jet. # Date Discharge Angle Area Opening Blade Pressure Manifold Manifold Manifold Uniformity Skewness Ranking

Setting Head Head Head From { ftl/s 2 {

0 - vertical} {in2

} {in} {£sQ {ft H20} {ft H20} {ft H20} Centerline

T-1 4/14/94 5.082 90 274.8 1.6 Uniform extremely extremely 10

non-uniform to the right

T-2 5/3/94 6.338 60 374.0 1.6 Uniform extremely right, slightly 9 -tied

non-uniform better than T-1

T-3 5/5/94 7.511 60 391.0 1.6 Uniform unchanged from unchanged from 9 -tied

T-2 T-2 T-4 5/6/94 7.003 60 396.0 1.6 Uniform non-unifonn, right, slightly 5

better than Demo better than Demo Demo 5/16/94 60 401.0 1.5 Uniform 2.0 unchanged from right, 6

T-4 worse than T -4

T-5 5/17/94 6.425 30 391.0 1.5 Uniform 2.0 non-unifonn, right, 8 - tied worse than T-8 worse than T-8

T-6 5/18/94 6.386 30 391.0 1.4 Uniform 3.0 unchanged from unchanged from 8 -tied

T-5 T-5 T-7 5/19/94 6.206 30 391.0 1.3 Uniform 3.0 unchanged from unchanged from 8 - tied

T-5 T-5

T-8 5/23/94 6.403 30 400.0 1.3 Uniform 3.2 non-unifonn, right, 7-tied

better than T-7 worse than T-7

T-9 5/24/94 6.167 30 400.0 1.4 Uniform 3.1 unchanged from unchanged from 7 - tied T-8 T-8

T-10 5/25/94 6.284 30 400.0 left= 1.2 Trapezoidal 3.3 unchanged from unchanged from 7 -tied right= 1.4 T-8 T-8

T-11 5/27/94 6.347 30 386.0 1.4 Uniform 3.0 unchanged from unchanged from 7-tied

T-8 T-8 T-12 6/1/94 6.492 30 386.0 1.2 Uniform 4.1 unchanged from unchanged from 7 -tied

T-8 T-8

T-13 6/8/94 6.341 30 386.0 1.6 Uniform 3.4 extreme, extreme right, II worse than T-1 worse than T-1

T-14 6/16/94 6.441 30 386.0 1.6 Uniform 2.9 7.68 6.87 4.53 unchanged from unchanged from 7 -tied

T-12 T-12 T-15 6/24/94 6.479 25 398.0 1.6 Uniform 2.5 7.45 6.875 4.968 slight, slightly right 2

better than T-16 better than T-16 T-16 6/30/94 6.420 25 363.5 1.6 Uniform 2.6 7.205 6.455 4.058 slight, right, 3

worse than T-15 worse than T-15

T-17 7/6/94 6.420 25 325.9 1.6 Uniform 2.8 7.965 7.175 4.508 slight, right, 4 worse than T-16 worse than T-16

T-18 7/19/94 6.420 25 398.0 1.6 Uniform 2.1 6.115 5.435 5.228 semi-unifonn, barely right, better than T- l 5 better than T-15


L.... c:::J CJ CJ CJ ::::J

Pit 4 Experiments The Pit 4 experiments are documented in the Pit 4 Slab and Buttress Foundation Scale Model Simulation report [10]. This section contains the Executive summary from that report.

Executive Summary Reclamation and Pacific Gas & Electric Company (PG&E) entered into Cooperative Research and Development Master Agreement (CRDA) No. Z-19-2-196-91 in December 1991. This agreement is under the authority of the Technology Transfer Act of 1986 (Public Law 99-502). Under the CRDA, Reclamation and PG&E will perform cooperative research in association with Reclamation's Water Technology and Environmental Research (WATER) program and the Department of the Interior Dam Safety Program.

Reclamation received a Request For Proposal (RFP) in September, 1992, from Pacific Gas & Electric Co., for a cooperative research study of the Characteristics of Dam Foundation Erosion. In response to the RFP Reclamation invited PG&E, Colorado State University, and Dr. George Annandale to form a study team. The Study Team responded to the RFP in a joint proposal February 1, 1993. PG&E responded favorably to the proposal and the Study Team began preparation of a Survey of Literature and a Pre-Test Report.

Reclamation and Colorado State University entered into Cooperative Agreement #1425-4-FC-81-19700 for completing a Pre-Test Report and seminar, and scale model and prototype model designs. A scope of work for clear water experiments and instrumentation design was part of this agreement. Colorado State University completed the scale model design in December, 1993, and completed construction of the 1:3 scale model facility in March, 1994. The facility simulates a free-trajectory jet, the type of flow that may occur at a concrete dam during an overtopping event.

In May, 1994, at the request of PG&E, the Study Team initiated a change in the scope of work of Cooperative Agreement #1425-4-FC-81-19700. The Study Team postponed the parts of the scope of work referred to as the "clear water experiments" and the instrumentation design tests . In their place the Study Team planned experiments simulating overtopping at the Pit 4 dam, a PG&E owned facility. The parameters of the experiments are described in documents supplied by PG&E [28]. PG&E supplied a sample of material from the downstream area of Pit 4 dam. Those materials are described in the section Pit 4 Material. The experiments include collecting data on extents and temporal changes of erosion only. The clear water experiments, instrumentation design, and remaining experiments were transferred into the scope of work for the new three year cooperative agreement currently being formulated.

Pit 4 Dam is located on the Pit River, in Shasta County, California, about 8 miles northwest of Burney, California. The dam, constructed in 1927, is a composite-type structure, with the right half being a spillway section and the left half a slab-and-buttress structure.

Experiments on the Pit 4 material satisfied the testing portion of the scale model aspect of Contract · No. 1425-4-FC-81-19700. This report presents the results and conclusions of those experiments. The scope of work includes two experiments. The first is a witness test, and the second is a record experiment. The witness test took place on July 26, 1994 with Mr. Ron Adhya, the PG&E Project Manager present. The record experiment took place on August 11-12, 1994.

On July 26, 1994, a witness test was performed in the Hydraulics Laboratory at Colorado State University. Attendees included Mr. Ron Adhya, PG&E; Dr. Rodney Wittler, Mr. Philip Burgi, and Mr. Brent Mefford, Reclamation; Dr. George Annandale, HDR Inc.; and Dr. James Ruff, Dr. Steven Abt, Mr. Thomas Brisbane, and Mr. Todd Lewis, Colorado State University. The model was prepared with the basin filled with 3 feet of Pit 4 material (scaled) and the jet manifold angle


of 30 degrees. The model was operated for approximately a I-hour period. Data were not taken during the witness test.

Subsequent to the witness test, the model was prepared for a record experiment of the Pit 4 scaled material. Several communications occurred between Colorado State University and Reclamation to determine material depth, jet angle, tailwater depth, discharge, experiment duration, and data collection times. The experimental parameters are:

• Jet/diffuser angle of 10 degrees from vertical

• Pit 4 material depth of 3 feet (Elevation 4 feet)

• Experiment duration of 2 hours

• Bed contouring at 15, 30, 60, and 120 minutes after the beginning of the experiment

• Tailwater sill maintained at 4 inches (model) above the initial bed level

• Discharge of 6.4 ft3/s. (22% of the PMF)

The Pit 4 material record experiment was conducted by Colorado State University on August 11-12, 1994. Dr. Rodney Wittler witnessed portions of the record experiment. A summary of the experiment results with plots are presented in the results section.

The Pit 4 material record experiment consisted of four flow periods. After each period of flow, the model was shut down and the surface of the model contoured. The surface was not relevelled. The following time increments (total elapsed time) comprised the four periods: 15 minutes, 30 minutes, I hour, and 2 hours.

Results show a maximum erosion depth of roughly 1.98 feet. Scaled, this depth corresponds to a depth of roughly 6 feet. The unit discharge of the model corresponds to a discharge 22 % of the PMF discharge.

Conclusions:

• All erosion results in this experimental series correspond to flow that is roughly 22% of the PMF of Pit 4 dam. This is a flow of 10.0 ft3/s/ft prototype scale or 1.92 ft3/s/ft model scale.

• The model equations significantly overestimate the erosion for model data.

• In general, the prototype erosion prediction formulas, Veronese, modified Veronese, and Mason prototype, overestimate the scaled erosion results from the simulation by roughly 70 %.

• The maximum erosion occurred within the first 12% of the total test time. The time to maximum erosion is undetermined, but progressivity in the simulation is practically nonexistent. The maximum erosion does not substantially change with respect to time.

• Operation of the 1 :3 scale model facility with non-cohesive material indicates a high potential for successful simulation of other earth materials. The test basin dimensions facilitate recirculation without constricting the return flow, and the depth of the basin appears adequate.


0

n fl

]

J

Publications

This section is an introduction to the published reports of the study. The section contains extensive summaries of the Pre-Test Report and Survey of Literature. The section also presents the Study Team plans for future publications. The Study Team intends to issue reports and technical publications throughout the course of the study.

Pre-Test Report and Survey of Literature

Pre-Test Report PG&E, EPRI, Reclamation, Colorado State University, and HDR Engineering are collaborating on improving technology for estimating the progressive extents of dam foundation erosion due to overtopping. The objective of the Pre-Test Report [8] is to review current technology and explain the basis for the development of new technology.

The collaborators propose an investigation of erosion of dam foundations due to overtopping. The primary objective of the investigation is to develop a scheme for estimating the progressive extents of erosion. The investigation involves researching existing methods and data, conducting a systematic series of physical model tests, and developing a computer model for simulating the progressive extents of erosion. A numerical model with properly formulated boundary conditions, simulating physical processes rather than parametric empirical correlation, will provide a useful tool for estimating progressive extents of dam foundation erosion.

Predicting flow patterns, velocity distribution, and other factors of impinging jets in prototype situations is largely beyond the capability of conventional physical and numerical modeling techniques. Numerous physical model studies described in the literature have limited application due to the uncertainty of scale effects associated with jet turbulence, jet coherence, jet air entrainment, and foundation material properties. Similar limitations are characteristic of existing numerical modeling techniques that omit the inherent complexities of both impinging jets and earth materials. The development of new technology to predict dam foundation erosion therefore requires application of specialized physical modeling and numerical analysis techniques.

The collaborators intend to conduct investigations in two physical models. The indoor laboratory scale is 1:3 following Froude criteria. The outdoor laboratory model is prototype scale. The 1:3

Dam Foundation Erosion Study Publications • 31

\ • I \ ( \ (\ /\ (\ - . (\ - r " (

scale model provides an economy of scale, accurately modeling some hydraulics, yet ignoring material properties and aeration effects. Accurate simulation of air-water and water-material interaction without scale effects requires a prototype scale model. The Pre-Test Report presents the collaborators plan for developing a new approach to estimate the extents of erosion coupling hydraulics and a geomechanical index system.

Survey of Literature A body of literature exists providing information about many facets of erosion due to plunging jets. The Survey of Literature [9] is an in-depth summary of literature pertaining to the Dam Foundation Erosion study. The summary provides background on overtopping, plunge pool scour, and culvert scour. Since overtopping erosion is similar to erosion in a plunge pool, or scour below a culvert, the subjects combine to provide a wide variety of prediction formulae and techniques.

The literature focuses on factors such as erosion, jet aeration, angle of impingement, and erosion extents. Erosion is dependent upon geotechnical and geomechanical properties of the foundation materials. The literature contains many formulas for estimating the ultimate depth of erosion. The majority of the formulas neglect the progressive nature of the erosion and instead concentrate upon ultimate scour depth. Most formulas also ignore aeration of the jet and the jet impingement angle.

The best formulas for estimating plunging jet scour, probably the formulas by Mason, have very narrow application. Mason acknowledges that accuracy greater than 70% is not readily attainable. Case studies show wide variances in the accuracy of the predicted and actual depths of scour. The reasons for the lack of accuracy are model specific formulas, site specific application, fragmented results from multiple studies, and the factors of geology and cohesive material properties. Current formulas have only a rudimentary capability of predicting progressive erosion. Improvements in this capability is crucial for accurately predicting cumulative erosion from multiple overtopping events.

The Survey of Literature documents three techniques for evaluating scour due to an impinging jet:

• Techniques that predict the erodibility of earth material .

• Techniques that estimate the depth of erosion, and

• Techniques that attempt to relate space and time in estimating erosion.

Techniques For Predicting the Erodibility of Earth Materials

Methods by Cameron (13), van Schalkwyk (26) Barton (12) and Kirsten, Moore and Annandale (19) result in estimates of the erodibility of earth material. Earth material erodes when the erosive power of the impinging water exceeds the ability of the material to resist erosion. Erodibility is therefore a threshold condition.

Techniques For Estimating the Extents of Erosion Mason and Arumugam (5) list 31 methods of calculating scour depth, and divide these into five groups. The first group, 17 equations, relates scour depth to discharge, head drop and characteristic particle size. The second group, 2 equations, adds the impact of tailwater depth. The third group, three equations, is empirical in nature, and relates estimated scour depth to jet dimensions and characteristics. The fourth group, eight equations, developed by six Russian authors, relate scour depth to drop height, particle diameter, tailwater depth and the angle with which the falling stream enters the downstream area. The fifth group, one equation, is for equations that include a time parameter. Mason (21) also treats the impact of air entrainment on plunge pool scour. The equations and associated coefficients of Mason and Arumugam (5) and Mason (21) are generally considered state of the art.


D Q

n

]

r

I )

The primary differentiation between culvert scour and plunge pool scour is the energy level and the angle of the flow at the point of impingement. Jets generally impinge in plunge pools at a near vertical angle, while flow from culverts generally impinges at an angle close to horizontal. Similar developments of parameters and scour prediction methods are available for culvert scour. Much of the work addressing erosion of cohesive materials and the importance of material properties is found in the culvert scour literature. Culvert scour researchers advance the most comprehensive set of formulae for predicting the extents of erosion as a function of time. A decaying exponential model is the primary model for correlating erosion extents to time.

Techniques For Estimating the Progressive Extents of Erosion The fifth group of equations recorded in the paper of Mason and Arumugam (5), one equation, is for analyses that include a time parameter, relating the depth of scour to time. The few attempts, made with the use of an explicit equation, to account for the progression of erosion as a function of time have not been very successful. However, many authors postulate the importance of erosion progression and case histories of Kariba dam (11), Tarbela dam (20)(25)(14), Guri dam (17), and Seven Mile dams (24) support the postulation.

State of the Art

This section presents the state of the art in four areas: Maximum scour depth, erosion extents and progressive or time based models, air entrainment, and angle of inclination. Where appropriate there are explanations of the perceived shortcomings of the formulae and or methodologies.

Maximum Scour or Erosion Depth

Veronese (6) and Mason (5) developed the most prominent scour equations. Equation 1 is the Veronese equation. Reclamation lists the Veronese formula in Design of Small Dams ( 16).

Y s = depth of scour below tailwater (in feet). H = effective head (in feet). q = unit discharge (in ft:3/s-ft).

(1)

The Veronese equation is unbounded, does not consider tailwater and neglects material properties. Equation 2 shows the equation by Mason. Note that Masons equation is dimensionally homogeneous.

D=depth of erosion/scour H = effective head h = tailwater depth q = unit discharge d = d90 of foundation material g = acceleration of gravity

(2)

The Mason equation is also unbounded, and while it does include a material factor, d, it is unlikely that this factor adequately represents the wide variety of materials and material properties. The reasons for endorsing the Mason formulas are the thoroughness of the research, the comprehensive nature of the data, including scale model studies and prototype case studies, and the dimensional analysis and dimensional homogeneity of the formulas.


Air Entrainment Mason modified his equation to account for air entrainment. The modified equation, Equation 3, is perceived to be state of the art considering air entrainment. The expression for /3, the volumetric air to water ratio, is from Ervine (18), and is shown in Equation 4.

D = 339qo.6o(l + /3)0.30 ho.16 g030d0.60

/3 = 0.13(1- Ve I v)(H I t)°·446

Erosion Extents and Progressivity

/3 = Volumetric air to water ratio H = jet fall height t = jet thickness v = jet impact velocity Ve = minimum jet velocity required to entrain air

(3)

(4)

Erosion extents and progressivity fall into two groups. The first derives from research on culvert scour and applies to low head, near horizontal jets. The second group derives from plunge pool research.

Culvert Scour

The prevailing model for progressivity by culvert scour researchers is a decaying exponential. The decaying exponential model may be appropriate as a first implementation of a progressive model. In homogeneo_us, heterogeneous, non isotropic material such as sand or clay, the model may produce accurate and precise results. In non ideal material conditions, the model may be too simple, degrading the accuracy and precision of the first order attempt to model progressivity.

Mendoza.,.Cabrales (22) studied scour cavities produced by different discharges of varying duration through circular culverts onto a horizontal sand bed (d50=1.86 mm, cr=l.33). He developed expressions describing depth, length, and volume of the scour hole as a function of time and of the

discharge intensity, DI= Qg-0

·5 n-2.s, that followed the decaying exponential model.

where:

ds = depth of the scour cavity below the elevation of the initial ground level, dsm = maximum scour depth a= constant, t= time from initiation of scour.

(5)

Kloberdanz (27) carried out a series of tests, and using data previously taken by Ruff, Abt, and other researchers derived empirical relations for calculating scour in culverts produced in noncohesive material. He considered, like Mendoza (22), characteristics of the particles such as size, and depth, length, and volume of the scour hole, as a decaying exponential time relationship.

Ds = l- e-(o.01s1+0.96)

Dsm


(6)

Publications • 34

[

I

I I I

Where:

W. = 1 _ e -(0.0161+1.88)

~m

Ls = l- e-(o.015r+o.41)

Lsm

Vs = 1 _ e - (0.0151+0.41)

vsm

W, =7.79Ds D D

Ds = 028( Vs )0.41

D D3

~ = 223( vs ) 0.42

D D3

Ls =6.9j~) D ,~D3

Ds = l.25(D.l.)°"81 D

~ = 9.75(D.J.)081 D

Ls = I3.49(D.l.)031 D

Vs3 = 3616(D.J.)2.08 D

r;; erg o.4 = 335 n.1.( iJ0) · [

o 2]0.57

D = culvert diameter D s = depth of scour hole D sm = maximum depth of scour hole d50 = median grain size diameter g = acceleration of gravity Ls = length of scour hole Lsm = maximum length of scour Q = discharge t =time Vs = volume of scour hole Vsm = maximum volume of scour hole Ws = width of the scour hole Wsm = maximum width of scour hole

(7)

(8)

(9)

(10)

(11)

(12)

(13)

(14)

(15)

(16)

(17)

(18)

g = geometry standard deviation of grain size = ( d84/ d 16) 05


d84 = particle diameter of a material for which 84 percent of material is finer by weight d16 = particle diameter of a material for which 16 percent of material is finer by weight

These formulae by Kloberdanz and others summarize a vast amount of data, most from prototype scale model studies. The limits of the formulae extend to the types of material in the studies. Material in the investigations by Abt, Shaikh, Doehring, Ruff, Mendoza, and others are almost exclusively homogeneous, heterogeneous sands or clays. The formulas do not apply beyond these limits.

Plunge Pool Scour

Chee and Padiyar (15) made model studies to determine scour depths resulting from 30° flip buckets, using uniform granular plunge pool materials. An additional, and potentially more useful part of their study was the development of a generalized scour hole geometry, as the report by Harza (23) notes.

"The shape of the hole in plan is symmetrical about the longitudinal axis with the deepest point located downstream of the geometrical center. To define the horizontal and vertical dimensions of the hole, the deepest point is taken as the origin with radius vectors originating from it. The reference axis is the zero degree radius vector point in the upstream direction.

The scour depth at any position measured from the surface water level along any radius vector is related to Dm and the ratio r!R. By curve fitting, the following equation was derived (units inft):

D= Dm (l +r I R)o92

where:

D = scour depth at any point along a radius vector Dm = maximum scour depth as given by Equation* (1) (ref 8) r = distance at any point along a radius vector R = length of the radius vector (measured to the rim of the hole)

Equation 19A is applicable to any radius vector and fixes the vertical dimensions of the hole.

(19A)

[

[

[

r [

To determine the horizontal coordinate, the length of the radius vector (R) I ts required. Many groupings of the significant variables have been attempted. The most success.fa/ correlation is given by Equation 19B (units in ft):

Re = C[(Dm -h) I hY[(H I d)Y (19B) B

where Re= length of radius vector at the angle B measured to the rim of the hole B = width of spillway flip bucket Dm = maximum scour depth as given by Equation* (1) (ref 8) h = downstream surface water depth referred to the original bed level H = head drop from water level upstream of spillway to water level at scour hole


I I

d = mean bed material size Equation (19A) and (19B) will determine the coordinates of the scour hole

from which the contours can be drawn. "

Conclusions The Veronese and Mason formulas do not offer sufficient treatment of aspects such as tailwater depth, material properties, angle of inclination, and others. The decaying exponential model is adequate for homogeneous, heterogeneous materials. However, to some extent the decaying exponential, and in all cases the power models are unbounded, that is they do not indicate an asymptotic approach to realistic equilibrium extents. Inclusion of aeration by Mason is a parametric empirical correlation. These shortcomings indicate the need to improve the technology of predicting erosion extents.

Publishing Schedule Members of the Study Team are authoring numerous articles related to the Dam Foundation Erosion study. This section includes articles scheduled for publication in 1995, including when available, an abstract of the article. '

American Society of Civil Engineers Journal of Hydraulic Engineering

Abt, S.R., Lewis, T.M., Wittler, R.J., Ruff, J.F., "Simulating Water Overtopping a Dam': Technical Note.

Wittler, R.J., Abt, S.R., Adhya, K., Lewis, T.M., "Pit 4 Simulations", Technical Note.

Wittler, R.J., Annandale, G.W., ''.An Algorithm for Estimating Progressive Extents of Erosion in Dam Foundation Material", Journal Article.

United States Bureau of Reclamation

Wittler, R.J., et. Al., 'Dam Foundation Erosion: Pre-Test Report': Final Report, US Bureau of Reclamation Water Resources Research Laboratory, December 1995.

Wittler, R.J., et. Al., 'Dam Foundation Erosion Survey of Literature': Final Report, US Bureau of Reclamation Water Resources Research Laboratory, December, 1995.

Wittler, R.J., et. Al., 'Dam Foundation Erosion Pit 4 Scale Model Experiments': Final Report, US Bureau of Reclamation Water Resources Research Laboratory, April, 1995.

Wittler, R.J., et. Al., 'Dam Foundation Erosion 1994 Year End Summary Report': Final Report, US Bureau of Reclamation Water Resources Research Laboratory, April, 1995.

Wittler, R.J., et. Al., 'Dam Foundation Erosion 1995 Year End Summary Report': Final Report, US Bureau ofRedamation Water Resources Research Laboratory, January, 1996.

Journal of Hydraulic Research

Annandale, G.W., "Erodibility". Journal of Hydraulic Research, May, 1995.


I\ ( \ ('\ ,11. /",(\) \ r\. .- _(\ A ( \

1995 First International Conference on Water Resources Engineering. August 14-18, 1995, San Antonio, Texas.

Spillway and Dam Foundation Erosion: A Study Predicting Progressive Erosion Extents by R.J. Wittler, B.W. Mefford, S.R. Abt, J.F. Ruff, G.W. Annandale

ABSTRACT Allowing a concrete dam to overtop during extreme flood events is one method of complying with State and Federal Dam Safety Regulations. Designing for dam overtopping requires an analysis of the erosion potential of the dam foundation and abutments. Current formulas for evaluating erosion have limited applicability. Existing formulas do not track erosion as a function of time, and have limited application in hard-rock or cohesive foundation materials.

PG&E, EPRI, Reclamation, Colorado State University, and HDR Engineering are collaborating on improving technology for estimating the progressive extents of dam foundation erosion due to overtopping. This paper presents case histories comparing erosion prediction methods, and explains the basis for the development of new technology. The collaborators propose an investigation of erosion of dam foundations due to overtopping. The primary objective of the investigation is to develop a scheme for estimating the progressive extents of erosion for cohesive and noncohesive materials as well as fractured rock masses. The investigation involves researching existing methods and data, conducting a systematic series of physical model tests, and developing a computer model for simulating the progressive extents of erosion. A numerical model with properly formulated boundary conditions, simulating physical processes rather than parametric empirical correlation, will provide a useful tool for estimating progressive extents of dam foundation erosion.

The collaborators intend to conduct investigations in two physical models. The indoor laboratory model scale is 1:3 following Froude criteria. The outdoor laboratory model scale is prototype scale or 1: 1. The 1 :3 scale model provides an economy of scale, accurately modeling some hydraulics, yet ignoring material properties and aeration effects. Accurate simulation of air-water and watermaterial interaction without scale effects requires a prototype scale model.

Waterpower 95. July 25-28, 1995. San Francisco, California.

Spillway and Foundation Erosion: Estimating Progressive Erosion Extents by R.J. Wittler, B.W. Mefford, S.R. Abt, J.F. Ruff, G.W . Annandale.

ABSTRACT Causal estimates of the Probable Maximum Precipitation (PMP) and Probable Maximum Flood (PMF) are generally larger than a statistical estimate based upon historical records . Over the past thirty years causal methods have replaced statistical methods for estimating the PMP. These changes in estimating procedures have made dam owners aware of deficiencies in spillway capacity. Dam owners, faced with this new awareness, must show regulating agencies a plan for satisfying a deficiency. Allowing a dam to overtop is an alternative for satisfying a spillway deficiency. This alternative requires an analysis of the potential for erosion of the dam foundation and abutments. Current methods of evaluating erosion extents have limited applicability. Existing erosion prediction formulas do not track erosion as a function of time, and have limited application in hard-rock or cohesive foundation materials.

Spurr, in a discussion of a paper by Mason [5], summarizes the problems with current foundation and abutment erosion prediction schemes:

"Thus the discusser contends that time must be considered together with the unique hydraulic and geological processes existing at each site, the amount of surplus energy contained by a given jet at impact over and above the threshold resistance of the bedrock to scour, the shape of the sides of the scour hole, and the size of the downstream bar in order to determine the plunge pool's maturity before any meaningful comparison can be made. This is specifically


I

]

] true when predicting scour in any plunge pool which does not respond as though its bed material were essentially non-cohesive. "

Mason in response to Spurr writes,

"The quantification of plunge pool scour rates, in conjunction with varying rock types is an area where much useful research remains to be done. "

The discussion by Spurr and Mason relates to research needs of Reclamation and other dam owners. The need for better analytical tools for analyzing erosion in the foundation and abutment areas of dams is increasing as costly alternatives to overtopping come under consideration. Indeed, if erosion due to overtopping does not place the dam in jeopardy, then alternatives such as spillway enlargement and foundation armoring become unnecessary.

PG&E, EPRI, Reclamation, Colorado State University, and HDR Engineering are collaborating to improve technology for estimating the progressive extents of dam foundation erosion due to overtopping. The new technology couples hydraulic parameters and a geomechanical index system in a numerical model simulating progressive erosion in the foundation and abutment areas of overtopped dams. The collaborators intend to conduct investigations in both 1 :3 scale and 1: 1 prototype models. The 1 :3 scale model provides an economy, while discounting material properties and aeration effects. The prototype model and specialized techniques are necessary for overcoming the limitations of other physical models. These limitations include scale effects associated with jet turbulence, jet coherence, jet air entrainment, and foundation material properties.

Spillway and Dam Foundation Erosion: Predicting Erosion Threshold by G.W. Annandale, R.J. Wittler, B.W. Mefford, S.R. Abt, J.F. Ruff

ABSTRACT This paper presents a new method, developed from field and laboratory data, to detennine the erodibility of rock and other earth materials. The method will be used in the development of a computer program for predicting the scour downstream of dams. The program is developed under contract to Colorado State University, in cooperation with the US Bureau of Reclamation, Pacific Gas & Electric Co., and the Electric Power Research Institute. The method is based on 150 field observations and 50 laboratory observations pertaining to erodibility. The threshold of erosion is defined by a relationship between a geomechanical index, known as the Erodibility Index, and the erosive power of water. The method has successfully been used on projects to determine erodibility of a variety of earth materials, ranging from fine and coarse grained granite (Bartlett Dam) to siltite and argillite (Cabinet Gorge Dam) to slickensided clays, fine sand and vegetated soils (Buffalo Bayo Erosion Control Project). The paper explains the basic principles of the method, illustrating how the ability of rock and other earth materials to resist erosion is determined and presenting a consistent method for estimating the erosive power of water. The paper concludes with a case study that deals with scour downstream of Bartlett Dam, Salt River Project, Arizona.

US.-Korea Joint Seminar on the Reduction of Natural Disaster in Water Environment. May 15-19, 1995, Seoul, South Korea

Design Flood Impacts on Evaluating Dam Failure Mechanisms by Steven R. Abt, Rodney J. Wittler, and James F. Ruff

ABSTRACT The implementation of the Probable Maximum Flood as the basis for the inflow design flood for evaluating dam safety has shown that existing analysis procedures and methods are inadequate. A collaborative team from the U.S. Bureau of Reclamation, Colorado State University, Pacific Gas and Electric Co., the Electric Power Research Institute, and HDR Engineering, Inc.", have identified three critical areas for additional dam safety research. Research programs are currently ongoing to investigate a) erosion protection and energy dissipation on embankment faces and spillways subjected to overtopping, b) erosion at the foundation and abutments of dams from overtopping, and c) embankment dam breach mechanics. Brief descriptions of each program are presented along with early project findings.


1 ..J

-,

J l -,

J

J J J ]

]

]

J

J

]

]

I I

I I I

Appendix A

This appendix contains the scope of work for the Cooperative Agreement between Reclamation and Colorado State University. The scope outlines in some detail the tasks and procedures for conducting the research study. The scope refers to numerical modeling. Colorado State University will subcontract the numerical modeling tasks to HDR Engineering Inc ..

Scope of Remaining Work The result of reevaluating the Probable Maximum Flood (PMF) of Reclamation dams in many cases is recognition of insufficient spillway capacity for passing the flood volume. This creates a need to upgrade the spillway capacity, allow overtopping of the dam, or remove the dam. State and Federal Dam Safety regulations require reasonable evidence that an overtopping scheme will not result in destabilization of the dam due to erosion in the foundation and abutment areas. Current methods of predicting and evaluating erosion extents have limited applicability. Existing erosion prediction formulas do not track erosion as a function of time, and have limited application in hard-rock or cohesive foundation materials . This goal of this cooperative study is to improve technology for predicting and evaluating the progressive erosion extents in the foundation and abutment areas of a dam due to overtopping.

Dam Foundation Erosion: Pre-Test Report PG&E, EPRI, Reclamation, Colorado State University, and Western propose a collaboration to improve technology for estimating the progressive extents of dam foundation erosion due to overtopping. A Pre-Test Report [8] reviews current technology and explains the basis for the development of new technology. The report presents the Study Team plan for developing a new approach to estimate the extents of erosion coupling hydraulics and a geomechanical index system. This scope of work summarizes the Pre-Test Report and presents the main points of the proposed study in a task based form.

Overview The Study Team proposes a study of erosion in the foundation areas of a dam under overtopping conditions. The primary objective of the study is to develop a scheme for estimating the progressive extents of erosion. The study involves researching existing methods and data,

Dam Foundation Erosion Study Appendix A • A-1

conducting a systematic series of physical model experiments, and developing a computer model for simulating the progressive extents of erosion. Numerical model developments with properly formulated boundary conditions, simulating physical processes rather than parametric empirical correlation's, may provide useful tools for estimating progressive extents of dam foundation erosion.

Predicting flow patterns and air concentrations of plunging jets in prototype situations is largely beyond the capability of conventional physical and numerical modeling techniques. Numerous physical model studies described in the literature have limited application due to the uncertainty of scale effects associated with jet turbulence, jet coherence, jet air entrainment, and foundation material properties. Similar limitations are characteristic of existing numerical modeling techniques that omit the inherent complexities of both impinging jets and earth materials. The development of new technology to predict dam foundation erosion therefore requires application of specialized physical modeling and numerical analysis techniques.

Colorado State University, with the assistance of the Study Team, intends to conduct experiments in two physical models at their Hydraulic Laboratories. The first model, located in the Hydraulics Laboratory at Colorado State University, will have a scale of 1:3 and follows Froude criteria. The second model, to be located at the Outdoor Laboratories, Engineering Research Center, Colorado State University, is prototype scale. The 1:3 scale model provides an economy of scale, accurately modeling hydraulics, with scale effects distorting material properties and aeration effects. Accurate simulation of air-water and water-material interaction without scale effects requires a prototype scale modeL Plans for the proposed prototype scale model are included in this scope. The 1:3 scale model is in place at the Hydraulics Laboratory, Colorado State University Engineering Research Center. The prototype scale model requires moderate modification of the existing overtopping facility at Colorado State University.

The experiments and analysis of these data will be performed by members of the Study Team. The Team is made up of the following persons and organizations .

Name Dr. Rodney J. Wittler*

Mr. Doug Morris Mr. Ron Adhya Professor James Ruff*

Professor Steven Abt* Mr. Greg Scott

Mr. Brent Mefford

*-Team Leader

Organization Reclamation TSC Water Resources Research Laboratory EPRI PG&E Colorado State University

Colorado State University

Role Team Leader, Reclamation Principal Investigator EPRI Project Manager PG&E Project Manager Prototype Model Team Leader, Numerical Modeling Coordinator Scale Model Team Leader

Reclamation TSC Geotechnical Geotechnical Engineering consultant Group 4 Reclamation TSC Water Peer Reviewer and Technical Resources Research Laborato!)'. Sp_ecialist

Overview of Experiments There are two parts to this study: Hydraulic Experiments and Material Experiments. The purpose of the hydraulic experiments is to identify the hydraulics of plunging, dissipating jets. The purpose of the material experiments is to identify the processes of erosion of earthen materials caused by a plunging dissipating jet. Each part contains plans for several series and types of experiments. Series refer to experiments intended to illuminate the physical processes of erosion, while types refer to the use or non-use of earthen materials in the experiments. The scale model facility offers economy, performing many series and types of experiments rapidly, with scale effects. The


[

r

I I I I

prototype facility offers an unprecedented opportunity for incorporating the effects of aeration and material properties without scale effects into erosion technology. Both facilities have plans for experiments with and without earthen materials in place. Table 6 summarizes the tasks that are described in the remainder of this scope of work. The schedule for the tasks is in the accompanying document, Schedule: Dam Foundation Erosion.

Table 6. Summary of tasks.

........................................ ~.~.':':!.~.~?.~~~ ..................................................................... Prototype Model······························· Instrumentation design

Clear water experiments Granular media experiments

Simulated Earthen Material Experiments Temporal effects experiments

Clear water correlation experiment Granular correlation experiment

Cubical slabs Vertically oriented slabs Upstream oriented slabs

Downstream oriented slabs Cohesive material

Cohesive material in slab joints Noncohesive material in slab joints

Other exeeriments as resources allow

The Hydraulic experiments include measuring flow variables such as velocity, discharge, pressure, rate of energy dissipation, turbulence intensity, angle of incidence, and others. The Material experiments include measuring material variables such as mass strength, particle size, relative orientation and interparticle strength. The material variables also include fundamental geotechnical and geomechanical properties. ·

Hydraulic Experiments

There are two facets to the hydraulic experiments, instrumentation design and clear water experiments. Measuring the hydraulic properties of a plunging dissipating jet requires new and unique instrumentation. The Study Team anticipates utilizing ground penetrating radar, air concentration probes, and high velocity Pitot tubes in various combinations in order to measure and track the progressive extents of erosion. The clear water experiments include measurement of hydraulic parameters such as velocity, aeration, discharge, etc.. The majority of the clear water experiments will occur in the scale model facility due to the economy of operating that facility. Experiments that require the most accurate simulation of physical processes will occur in the prototype facility. The scale model facility will serve as a screening facility wherein multiple configurations will be attempted to assessing the potential value of a prototype scale experiment.

A rectangular sharp-edged orifice at the terminus of a delivery pipe will simulate the overtopping phenomenon. Placing an orifice near the terminus of a pipe, issuing through the side wall, presents a complex design problem. A jet issuing from the orifice must be coherent and uniform and the jet must issue perpendicular, in the horizontal plain, from the pipe. Achieving these design goals requires model study to produce precise design specifications. A scale model facility provides the apparatus for designing an orifice to these specifications. These requirements were met under Cooperative Agreement #1425-4-FC-81-19700, between Colorado State University and Reclamation. Therefore, the scale model facility already provides the apparatus for continuing research into erosion in the foundation area of a dam.

Measurement of hydraulic factors requires complex instrumentation and measurement schemes. The purpose of the measurements is to gain an understanding of the hydraulics of a plunging dissipating jet of water, and then to be able to predict the hydraulics in specific situations. This study calls for development of various instruments and measurement schemes in the scale model facility. Variables requiring measurement include discharge, head, tailwater depth, velocity profiles and pressure distributions along numerous non orthogonal axes and at many sections, and


other factors. Plans for these aspects are under preparation as part of the extension to Cooperative Agreement #1425-4-FC-81-19700.

Material Experiments There are two facets to the material experiments. First are screening experiments in the scale model facility and second, primary experimenting in the prototype facility. Fractured slabs of rock, and mixed materials with widely varying size fractions, are not specifically treated by formulas by Mason [5] or Veronese [6]. Therefore it is difficult to anticipate the erosion characteristics of these materials and configurations.

Preliminary experimenting in the scale model facility will provide a frame of reference for the behavior of non-homogeneous, non-heterogeneous material. The intent is to screen a significant number of material configurations in the scale model facility, discounting the scale effects. The screening provides a basis for evaluating materials and material configurations for experimenting in the prototype facility. Since resources limit the number of experiments in the prototype facility, insight from experiments in the scale model facility will assure optimum value of data from the prototype facility.

The number, type, and combination of materials constituting the foundation of a dam are very numerous. It is imperative that limiting assumptions aimed at reducing the number of permutations of combinations be logical. This study is adopting a geomechanical index system by Moore, Kirsten [l], and Annandale [2][4] for describing the type, number, combination, orientation, and other properties of foundation materials. The Erodibility index, Kn, is the product of four factors quantifying fundamental properties of earthen materials. The four factors are the Mass Strength Number, Km, Relative Ground Structure Number, K., Block Size Number, Kb, and the lnterparticle Strength Number, K.i. The basis ohhis study is the correlation between the Erodibility Index and the rate of energy dissipation.

Most materials of interest to this study have relatively similar mass strength. Similarly, interparticle strength does not appear to be the primary focus area of this study. Therefore for the purpose of this study the mass strength number and interparticle strength numbers are considered constant. The particle block size and the relative orientation are the primary material variables for this study. Preliminary calculations (See the Facilities section of the Pre-Test Report) indicate that the proposed prototype facility has the capacity to erode two inch to ten inch material to a depth of roughly ten feet. The relative orientation will vary from dipping into the flow, vertical with respect to the flow, and dipping away from the flow.

Details of Scale Model Facility Experimental Series The first purpose of hydraulic experiments in the scale model facility is to develop technology for predicting the primary flow patterns in an eroding scour hole. The second purpose is to screen a significant number of material configurations in the scale model facility, narrowing the number and range of the variables in the prototype facility. The third purpose is to design the orifice and instrumentation for the prototype facility. The orifice design was completed under Cooperative Agreement # l 425-4-FC-81-19700, between Colorado State University and Reclamation. Instrumentation includes velocity meters, air concentration probes, pitot tubes, ground penetrating radar and low frequency sonar (for actively tracking the erosion extents), video and photography equipment, pressure transducers, and piezometer tubes.

Experiment Series in the Scale Model Facility

Facility Operation

There will be a series of experiments for learning operating · characteristics of the facility, regulating flow, manipulating jet characteristics, and collecting data.


I

[

I I I I

Instrumentation Design

Measurement of hydraulic properties requires complex instrumentation and measurement schemes. Engineers and Technicians will develop various measurement instruments and schemes in the scale model facility. Standard flow and pressure instrumentation will produce data in non aerated portions of the flow field. Special devices, a back-flushing pitot tube and air concentration probe, developed by Reclamation, will also be utilized in the experiments. Automated PC data acquisition will speed data collection and ensure uniformity of data quality. A series of experiments will show the best strategy for producing the necessary data for quantifying the flow field, and calculating rate of energy dissipation in the eroding scour hole.

Highly aerated, high-velocity (12-15 mis) flow increases the difficulty of velocity measurements with "off the shelf'' instruments. · Although air concentration measurement devices exist, they are not generally available for purchase. As a result, Reclamation, with Colorado State University, developed instruments for this environment as part of the Overtopping research study, Cooperative · Agreement# l-FC-81-17790.

The air probe acts as an air bubble detector. The air concentration measurement operates on the difference in electrical resistivity between air and water. The air probe consists of two conductors, a tip of a small insulated platinum wire encased in a stainless steel sleeve. An air bubble (0.2 mm or less) passing across the probe tip breaks the current between the two conductors and increases the resistance lowering the voltage across the probe. Integrating the resulting signal over a period oftime yields the probability of encountering air in the air/water mixture.

A velocity probe requires a simple and stout instrument. Reclamation developed a pitot-static tube (originally designed for mounting on the fuselage of an airplane) with constant back flushing flow to keep air out of the system. A differential pressure cell measures the total head difference created by the flowing water passing the static and dynamic ports and displacing the back flow.

Both probes require laboratory calibration to establish relationships to known values or baseline information and reliability. Technicians balanced the air probe in non aerated water and then calibrated with a pipe system with known volumes of air and water. This study will employ both

· instruments to establish velocity and aeration profiles in the scour hole. Early results from the Reclamation study confirm the accuracy and precision of the probes. ·

Cl~ar Water Hydraulic Experiments

An undefined area of jet mechanics is interaction of the impinging jet with varying fixed geometry. As a jet impinges on the water surface it diverges and may split into two or more directions as well as stagnate at the point of contact with a boundary. This mechanism requires laboratory study and the scale model facility is the appropriate and economical facility for this study. A series of experiments with fixed geometry will show how an impinging jet splits when encountering positive, horizontal, and adverse slopes, as well as a concave shape, similar to the bottom of a scour hole.

As an extension to Cooperative Agreement #1425-4-FC-81-19700, between Colorado State University and Reclamation, a subset of the clear water experiments, described in the Pre-Test Report, are under way at Colorado State University in the scale model facility. Details of the experimental plans are available from Reclamation's Water Resources Research Laboratory, D-8560, and are a part of the documentation of the agreement extension and results. This series of experiments will continue and expand in the proposed study.

Granular Media Experiments

This series includes but is not limited to scale versions of all experiments planned for the prototype facility. In addition to these experiments, variations will be tested to bracket the behavior of the variables of interest. The Study Team will formulate the experiments constituting this series of experiments based upon data and information developed during the study. The scope of these


experiments may be changed as the study progresses with mutual agreement between the Study Team members.

Simulated Earthen Material Experiments

The criteria for this series of experiments includes three values of the relative ground structure, Ks, 45° dip into the flow, perpendicular to the flow, and 45° dip away from the flow, and three values of the block size, Kb, 2, 6, and 10 inches. A sub-series of experiments will vary the aspect ratio of dimensions of the blocks. The initial experiments will utilize blocks with an aspect ratio of 1: 1: 1 (x, y, z), while future experiments will vary the aspect ratio to 1:2:1, 1:4:1, and resources permitting, others.

Granular Media Experiments: Temporal Effects

The scale model facility will be useful for identifying temporal effects of the erosion process. The Study Team will test the thesis of numerous investigators who assert that the majority of erosion occurs in a relatively short time period, and that the progressive nature of erosion is marginal or too complicated to precisely model. A series of experiments in the scale model facility will serve to quantify the effects that time dependence has upon the extents of erosion. The following table details this series of experiments. Note that the first two columns show successive experiments, stepping the discharge up and then down, without leveling the basin material. The third and fourth columns show experiments that also step the discharge up, but after each experiment, the material is relevelled, negating any influence of preceding experiments. The intent is to compare the e>..1ents produced by each series of experiments and discern the temporal effects of progressive erosion. This series of experiments will utilize a homogeneous, heterogeneous, noncohesive granular material.

Table 7. Experiment series for identifying temporal effects of erosion.

No Leveling Leveling

Discharge Experiment Duration Discharge Experiment Duration

25 fl:3/s Equilibrium 25 ft3/s Equilibrium, relevel

50 fl:3/s Equilibrium 50 ft:3/s Equilibrium, relevel

75 ft:3/s Equilibrium 75 ft:3/s Equilibrium, relevel

100 :ft:3/s Equilibrium 100 fl:3/s Equilibrium, relevel

75 ft:3/s Equilibrium

50 ft:3/s Equilibrium

25 :ft:3/s Equilibrium

Summary

The Study Team plans 6 series of experiments in the scale model facility: 1.) facility operation, 2.) instrumentation design, 3.) clear water hydraulics, 4.) granular media, 5) Simulated Earthen Materials, 6) temporal effects.


I I I I I I I

Details of Prototype Scale Facility Experimental Series There are two series of experiments planned in the prototype facility. The first is full scale measurement of aeration, flow distribution patterns, and hydraulic experiments to contrast or match those in the scale model facility. The second is a series of experiments on various types of materials.

Facility Plans The prototype scale facility is adjacent to the overtopping research facility at Colorado State University. Construction of the prototype facility requires additions and modifications to the overtopping facility. Many of the components of the overtopping facility will be utilized for the prototype facility. The following figures depict the plans for the prototype scale model facility.

PL..MPBACK SYSTEM

2J SLOPE OVERTOPPING FACILITY

NEW 3' DIAMETER FEEDER PIPELINE

3 FT DIAMETER SUPPLY PIPELI\IE FROM HORSETOOTH RESERVO~

X 0 a, ,.! < ....

DAM FOUf\OA TION

EROSION FACILITY

>-~ Q 0 a:

WASTEWAY

N Figure 22. Plan of proposed additions and modifications to existing overtopping facility at Colorado State University. Note tap into existing water supply system and common usage of tailbox and wasteway.

L 5 XS X 3/.4

TITLE. TALfOX ASS:1"8... 't DATE A/A/$

Q-Wl,EL FCR N5ffil..1£NTATO,I

Figure 23. Vies of the prototype scale facility.


I\ (\

Experiment Types in the Prototype Model Facility The depth of material for all experiments utilizing earthen or simulated earthen materials will be ten feet. Tailwater levels will be determined after further consultation with the Study Team. All slab materials will be concrete. Colorado State University will provide all experimental materials.

Facility Operation

There will be a series of experiments for learning operating characteristics of the facility, regulating flow, manipulating jet characteristics, and collecting data.

Clear Water Correlation Experiments

The purpose of these experiments is to correlate the behavior of plunging dissipating jet in the prototype model with that in the scale model. This correlation is important for establishing similitude between the two facilities. With similitude established, the screening experiments in the scale model facility can begin, with confidence that the results from the scale model accurately indicate the results that would occur in the prototype model.

Granular Media Correlation Experiment

The purpose of this experiment is to correlate the erosive processes in the prototype model with the scale model. This correlation is important for establishing similitude between the two facilities. With similitude established, the screening experiments in the scale model facility can begin, with confidence that the results from the scale model accurately indicate the results that would occur in the prototype model.

Cubical Slabs

This experiment will utilize concrete slabs with a 1: 1: 1 aspect ratio, with sides between 2 and 10 inches in length. These slabs will exhibit a unique value of the Erodibility Index, Kn. The purpose of the experiment is to determine the erodibility of uniformly sized blocks, and compare this erodibility with other size, shape, and orientation configurations.

Vertically Oriented Slabs

This experiment will utilize slabs of aspect ration 1:1:4, with the short sides between 2 and 3 inches, and the long side between 8 and 12 inches. The long side of the slabs will be oriented in the vertical direction. These slabs will exhibit a unique value of the Erodibility Index, Kn. The purpose of the experiment is to determine the erodibility of vertically oriented, elongated slabs, and compare this erodibility with other size, shape, and orientation configurations.

Upstream Oriented Slabs

This experiment will utilize slabs of aspect ration 1: 1: 4, with the short sides between 2 and 3 inches, and the long side between 8 and 12 inches. The long side of the slabs will be oriented in the upstream direction at a yet to be determined angle. These slabs will exhibit a unique value of the Erodibility Index, Kn. The purpose of the experiment is to determine the erodibility of upstream oriented, elongated slabs, and compare this erodibility with other size, shape, and orientation configurations.

Downstream Oriented Slabs

This experiment will utilize slabs of aspect ration 1:1:4, with the short sides between 2 and 3 inches, and the long side between 8 and 12 inches. The long side of the slabs will be oriented in the downstream direction at a yet to be determined angle. These slabs will exhibit a unique value of the Erodibility Index, Kn. The purpose of the experiment is to determine the erodibility of downstream oriented, elongated slabs, and compare this erodibility with other size, shape, and orientation configurations.


I I I

Cohesive Material

The purpose of this experiment is to determine progressive extents of erosion in a cohesive material such as a medium clay. The experiment is similar in scope to the granular media experiments. This experiment may be repeated in the scale model, resources permitting, in order to establish a correlation for cohesive materials.

Cohesive Material in Slab Joints

This experiment will utilize slabs of aspect ration 1:1:4, with the short sides between 2 and 3 inches, and the long side between 8 and 12 inches. The long side of the slabs will be oriented at a yet to be determined angle. The purpose of this experiment is to determine progressive extents of erosion in a simulated fractured rock matrix with cohesive material such as a medium clay in the fracture joints. This experiment may be repeated in the scale model, resources permitting, in order to establish a correlation.

Noncohesive Material in Slab Joints

This experiment will utilize slabs of aspect ration 1: 1 :4, with the short sides between 2 and 3 inches, and the long side between 8 and 12 inches. The long side of the slabs will be oriented at a yet to be determined angle. The purpose of this experiment is to determine progressive extents of erosion in a simulated fractured rock matrix with noncohesive material such as masonry sand in the fracture joints. This experiment may be repeated in the scale model, resources permitting, in order to establish a correlation.

Additional Experiments

Resources permitting, additional experiments may be planned for the prototype scale model facility. If so, the Study Team will come to a mutual agreement on the number and scope of the additional experiments. The purpose of the experiments is to 'fill in" gaps in the analysis that may be apparent from the analysis at this point in the study.

Summary

The proposed additions and modifications to the overtopping facility are shown in Figure 22. The Study Team plans eleven types of experiments in the scale model facility: 1.) facility operation, 2.) clear water correlation experiments, 3.) granular media correlation experiment, 4) cubical slabs, 5) vertically oriented slabs, 6) upstream oriented slabs, 7) downstream oriented slabs, 8) cohesive material, 9) cohesive material in slab joints, 10) noncohesive material in slab joints, 11) additional experiments as resources permit.


Numerical Model Developments During the course of this study numerical models will be developed to aid in the simulation of the processes of erosion. To be of interest to Reclamation the numerical model development should follow the following guidelines. ·

Graphical Basis & Programming Computer programs should operate in a Microsoft Windows™ 3.1 environment. Code should be developed in the Visual Basic 3.0 environment. The interface may call one or more Dynamic Link Libraries (DLL) that the Microsoft™ Fortran 5.1 compiler creates. The DLL's should be modular, each containing the code for a segment of the physical process simulation. The graphical interface should also communicate with other pre- and post-processing software such as Excel™, Visual CADD™, and Visio™.

Segmented Process Simulation Numerical models should consist of a collection of procedures. Each procedure should represent a specific component of the process or act as a global facilitating procedure such as time keeping. Procedures might include input hydrology, hydraulics of free trajectory or supported jets, jet suppression or contraction, jet/tailwater interaction, erodibility characteristics of the bed material, and water/bed material interaction.

Hydrology

The numerical model requires a hydrograph representing the Outflow Design Flood (ODF) as input. This information can be obtained by making use of independent software, such as HEC-1 .

Hydraulics

A numerical model should simulate discharge of water as it flows through critical depth at the spillway section and forms either a plunging or suppressed jet. The user should supply information regarding the jet formation. Jet suppression or contraction, analysis determining the trajectory, free or supported, may require additional independent model studies by the user prior to usage of the numerical model. The model should have the ability to model any jet, from the crest of the dam downstream.

Plunging Jet

The characteristics of a jet as it plunges through the atmosphere should be modeled. These characteristics include the entrainment of air and the subsequent separation of the jet into a central core and an outer zone. The central core contains no eritrained air, whereas the entrained air in the outer zone decreases the density of this part of the jet. The decrease in density of the outer zone reduces the erosive power of the jet. In addition, a computer program should have a facility to determine whether the central core of the jet will be diffused completely, or whether it will remain intact as it discharges into the plunge pool.

Supported Jet

A numerical model should have the ability to simulate discharge and entrainment of air within the boundary layer as water discharges down a spillway chute or along abutments.

Jet/Tailwater Interaction

The characteristics of the jet/tailwater interaction depends on the jet type. A numerical computer model should have the ability to simulate the interaction for both plunging and suppressed jets. Two-phase flow develops when a plunging jet dives through the surface of a plunge pool or tailwater. The region below the water surface may consist of either one or two zones, a transition zone or a fully developed two-phase flow zone. A transition zone exists when the central core of


I I ]

the jet is still intact when the jet impacts the water surface. The diffusion of the central core of a jet takes place when water and air are entrained from the surrounding environment below the water surface, giving rise to the transition zone. The fully developed two-phase flow zone commences at the point where the central core of the plunging jet is completely diffused. The modeling of turbulence intensity in both the transition and fully developed two-phase flow zone is important because it is used to quantify the magnitude of the erosive power of water. A numerical model should be able to determine the relative turbulence intensity as a function of depth in both the transition and fully developed two-phase flow zones . This could be done by utilizing further development of theory and empirical observations pertaining to plunging jets [7], and by making use of measurements and observations from the scale and prototype model studies.

• The interaction of the suppressed jet and the tailwater is likely to occur as a hydraulic jump. The extensive literature on the behavior of hydraulic jumps should be used to model this interaction (see literature survey pertaining to this investigation). A computer model should identify the type of jump, simulate the hydraulics and determine the relative magnitude of the associated turbulence intensity. This could be done by calculating the rate of energy dissipation in the vicinity of the hydraulic jump.

Erodibility

A numerical model should determine the erodibility of earth material by making use of a threshold relationship between the erosive power of water and the relative erosive resistance of earth material. Figure 24 represents the threshold relationship determined for earth materials such as jointed and fractured rock, weathered rock, detritus, cohesionless granular material, and cohesive material) by analyzing field observations pertaining to the erodibility of emergency spillways (Annandale [2]). The erosive power of water is represented by the rate of energy dissipation, and the relative ability of earth material to resist erosion is represented by the Erodibility Index. The rate of energy dissipation was found to be a good measure of turbulence intensity, with turbulence intensity in tum being a good measure of the relative magnitude of pressure fluctuations . The Erodibility Index is a product of factors representing the mass strength, block or particle size, interparticle strength and relative orientation of earth materials [2].

Rate of Energy Dissip-ation

(IN-//m)

1E+6~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

1E+5 ·-····-···············-·-·-····-- ·······-i---- --··-··-·--··-------···--··-

1E+4 • • 1E+3

Erosion No Erosion Threshold • 0 -------·····---·-········ ----·-··· ···------------·-···-·········---·····-··· ··

., -................. -f ......

; I • .,,..,,..

·· ··:······ ........ ····-·• .. ·············:·;~-->/-

.,....,,.,,..,,,,. ,,,... ..... ,.,,..

;;·r ,,..;.:·····················-·····

i • • • • .o .......... 1 • 1 E+2 ·········· ··-·· ··-···········11·-·-······-·- • ·· ·············• · ···· ·-·-····- ;_-;;/ -·;-·· • · ····--·-····.· . . . ----

• . Q _/ 0 1 E+1 ····-···········- -·~-.• • .;·-·f ·,; ·-·-.--·- · · _:..-"""'-::···· ···- · ··· ·-·-······-·· ·····-·-·-················-·-·· ·· ····-··· -··· -········- ·

• •. •... ... • "'p-~ 0 0 c§) . 0 ;

1E+o - :•·:iP'f~-o~ · -g ; ; --:~ py;/~Joce~ -s-- -~1 DO ---[O

0 0.1 1 10 100 1,000 10,000 Erodibility Index (Ki,)

Figure 24. Stream Power versus Erodibility Index showing the erosion threshold.


Foundation Material/Jet Interaction

The bed material/water interaction could be simulated in a computer program by comparing the erosive power of plunging or suppressed jets with the relative ability of earth material to resist erosion during each time step. A computer program could simulate the displacement of the erodible material when the comparison indicates that the material will erode. Displacement of bed material requires recalculation of the Erodibility Index and the erosive power of the jet for use in the next time step. The value of the Erodibility Index is a function of bed geometry relative to flow direction and should therefore be recalculated whenever the bed geometry changes. The need to recalculate the erosive power of the jet is also based on the dependence of this variable on the geometry of the plunge pool or tailwater environment.

Mass wasting

Mass wasting occurs when saturation of the earth material downstream of the dam increases effective stress, resulting in slope instability and mass failure. The first approximation of this process involves a stable angle of repose, (j>, and a critical mass wasting angle, x. A computer program could interrogate these values each time step. If the repose angle in the scour hole exceeds X, then the material will be laid back to the angle <I> in one time step. The material between x and (j> becomes part of the mass continuity procedure ending up as input into the displacement procedure.

Displacement

Displacement occurs after dislodgement. Initially, there could be two options for this procedure. The first is to use a sediment transport algorithm, the second is to treat the scour hole as a reverse action settling basin. Sediment transport is a function of rate of eriergy dissipation, a quantity that the program computes each time step. The ability of the water to displace the dislodged material will be determined by computing the available power of the discharging water with the displacement requirements of the dislodged material. The power that dislodged material requires for displacement is proportional to the product of the material weight and the settling velocity. If the available power of the discharging water is equal to or greater than the power requirement for displacement, the material will displace. Otherwise the material will remain stationary. A settling basin operates on the concept of fall velocity. If the prevailing current exceeds the fall velocity of the particles, the net displacement is along the current path, otherwise the particle settles.

Mounding

Mounding occurs in the zone downstream of the scour hole where mined material is deposited when the transport capacity of the flow diminishes.

Tailwater

Tailwater is a boundary condition. The computer model HEC-2 or other backwater analysis programs calculate values for the tailwater elevation.

Refinement Process As data, information, and analysis of the model investigations accumulates, these procedures modeling the physical processes could be refined and upgraded. The simplified procedures that might constitute a numerical model may evolve as the new technology develops. A modular design of a computer program facilitates changes to individual procedures.


{

(

[

]

Reports & Meetings Documentation and communication are essential to the success of the project. This section details the plan for creating strong communication between the Study Team, funding partners, and outside interests. This section also presents the plan for documenting the project incrementally and summarily.

Meetings Resource limitations dictate a minimum number of face to face meetings. The Study Team plans to hold two meetings per year. One meeting of the Study Team will be held during the summer testing period in Fort Collins, Colorado, facilitating witnessing prototype and scale model facility tests in progress. The PG&E Project Manager and key personnel will be in attendance at the Colorado meetings. Invitations to the Colorado meetings will be open to all interested parties since these meeting will coincide with testing in the two facilities.

A second meeting of the Study Team may be held in California at either the San Francisco PG&E Headquarters or in Palo Alto at EPRI headquarters, for presentation of milestone reports and decision documents. The Study Team Leader and key personnel will be in attendance at the California meetings.

Reports

The Study Team Leader will forward financial reports to the respective funding organizations as set forth in the agreements for this study. The funding organizations and notifying officials are:

Ron Adhya, P .E. Senior Consulting Engineer Pacific Gas & Electric Company One California Street, Room F-1758 San Francisco, CA 94177

Professor James F. Ruff Engineering Research Center Colorado State University Fort Collins, CO 80523

Dave Achterberg Chief, Dam Safety Office D-6600, PO Box 25007 Denver, CO 90225

Doug Morris Electric Power Research Institute 3412 Hillview Ave. PO Box 10412 Palo Alto, CA 94303

Dr. Stanley L. Ponce Research Director Office of the Commissioner US Bureau of Reclamation D-6700, POB 25007 Denver, CO 80225


Lloyd M. Greiner Assistant Administrator for Engineering Dept. of Energy Western Area Power Administration 1627 Cole Blvd., A2000 Golden, CO 80401-0098

Team leaders will produce progress reports for submittal to the Study Team Leader upon completion of study milestones and on a quarterly basis. All reports will be submitted to the Study Team Leader in both hard copy and electronic copy, specifically either Word Perfect 5.1 for MS DOS, Word Perfect 6.0a for Windows, or Word for Windows 6.0a format. All spreadsheets will be submitted in MS Excel 5.0 format. All CAD drawings will be in Visual CADD 2.0 format. If computer program file formats change over the course of the study, the Study Team Leader will notify the Team Leaders. Within two weeks of the first day .of each quarter or completion of a study milestone, the Study Team Leader will forward a digest of the reports to the Team leaders and following individuals and organizations:

Ron Adhya, P .E. Senior Consulting Engineer Pacific Gas & Electric Company One California Street, Room F-17 5 8 PO Box 770000 San Francisco, CA 94177

Professor James F. Ruff Engineering Research Center Colorado State University Fort Collins, CO 80523

Dave Achterberg Chief, Dam Safety Office Office of the Commissioner US Bureau of Reclamation D-6600, PO Box 25007 Denver, CO 90225

Dr. Stanley L. Ponce Research Director Office of the Commissioner US Bureau of Reclamation D-6700, POB 25007 Denver, GO 80225

Doug Morris Electric Power Research Institute 3412 Hillview Ave. PO Box 10412 Palo Alto, CA 94303

Lloyd M. Greiner Assistant Administrator for Engineering Dept. · of Energy


[

[ r

[

[

[

I I I I I I

Western Area Power Administration 1627 Cole Blvd., A2000 Golden, CO 80401-0098

The Scale Model and Prototype Model Team Leaders will, in consultation with the Study Team Leader, indicate the number and type of theses and or dissertations that will result from the study. Any dissertations or theses produced as a part of this study will be issued in report form to Reclamation prior to compilation of the final report. Both a hard copy and electronic copy will be issued to Reclamation.

As the study nears completion, the Team leaders and Study Team Leader will compile a final report. Reclamation will be the lead organization in the compilation of the initial draft. Colorado State University is responsible for preparation of sections of the draft report related to the team disciplines including graphics, data tabulation, analysis, and conclusions. The team disciplines are scale model experiments and operation, prototype model experiments and operation, and numerical model developments. The other organizations in the Study Team may contribute to portions of the draft. All Study Team members will review and edit the draft prior to issuance of the final report by Reclamation. The final report will summarize all activity during the project, present the major accomplishments, tabulate all data, and publish numerical model developments.

References [l] Kirsten, H.A.D., "A Classification System for Excavation of Natural Materials", The Civil

Engineers in South Africa, South Africa Institution of Civil Engineers, July, 1982.

[2] Annandale, G. W., "Erodibility", Journal of Hydraulic Research, 1995.

[3] Kirsten, H.A.D., "Case Histories of Groundmass Characterization for Excavatability': Rock Classification Systems for Engineering Purposes, ASTM STP 984, Louis Kirkaldie, Ed., American Society for Testing and Materials, Philadelphia, PA, pp. 102-120, 1988.

[4] Annandale, G.W., "Analysis of Complex Scour Problems in Rock and other Earth Materials': Proceedings of the Northwest Hydroelectric Conference, Portland, Oregon, 1993.

[5] Mason, P.J., Arumugam, K., "Free Jet Scour Below Dams and Flip Buckets': Journal of Hydraulic Engineering, Vol. 111, No. 2, ASCE, February 1985.

[6] Veronese, A., 'Erosioni de Fonda a Valle di uno Scarico': Annali dei Lavori Publicci, Vol. 75, No. 9, pp. 717-726, Italy, September 1937.

[7] Ervine, D.A., Falvey, H.T., "Behavior of Turbulent Water Jets in the Atmosphere and in Plunge Pools", Proc. Instn Clv. Engrs., Part 2, pp. 295-314, 83, March 1987.

[8] Wittler, R.J., et. al., "Dam Foundation Erosion: Pre-Test Report': Release Draft, PAP 643, US Bureau of Reclamation Water Resources Research Laboratory, October 1993.

[9] Wittler, R.J., et. al., "Dam Foundation Erosion Survey of Literature': Release Draft, PAP 628, US Bureau of Reclamation Water Resources Research Laboratory, August, 1993.

[10] Wittler, R.J., et. al., "Pit 4 Dam Slab and Buttress Foundation Scale Model Simulation", US Bureau of Reclamation Water Resources Research Laboratory, March, 1995.

[11] Akhmedov, T. Kh., ''Calculation of the Depth of Scour in Rock Downstream of a Spillway': Water Power and Dam Construction, December 1988.

[12] Barton, N., 'Rock Mass Classification and Tunnel Reinforcement Selection Using the QSystem': Rock Classification Systems for Engineering Purposes, ASTM STP 984, L.


Kirkaldie, Ed., American Society for Testing and Materials, Philadelphia, Pennsylvania; 1988.

[13] Cameron, C.P., Cato, K.D., McAneny, C.C., May, J.H., "Geotechnical Aspects of Rock Erosion in Emergency Spillway Channels - Analysis of Field Data and Laboratory Data': Technical Report, Vol. 2, U.S . Army Corps of Engineers, Washington, 1988.

[14] Chao, P.C., 'Tarbela Dam-Problems Solved by Novel Concretes': American Society of Civil Engineers Civil Engineering, Vol. 50, No. 12, pp. 58-64, December 1980.

[15] Chee, S.P., Padiyar, P .V., ''Erosion at the Base of Flip Buckets': Engineering Journal, Canada, Vol. 52, No. 11, pp. 22-24, November 1969.

[16] Design of Small Dams, United States Department of the Interior, Bureau of Reclamation, third edition, 1987. Denver, Colorado.

[17] EDELCA Report, "Guri Final Stage Spillway Buckets", 1978.

[18] Ervine, D.A., 'The Entrainment of Air in Water. " Int. Water Power and Dam Constr., 28(12), 27-30. 1976.

[19] Kirsten, H.A.D., Moore, J. S., Annandale, G. W., "Empirical Classification for Hydraulic Erodibility of Natural and Engineered Earth" 1993.

[20] Lowe, J., et al., 'Tarbela Service Spillway Plunge Pool Development': International Water Power and Dam Construction, Vol. 31, No. 11, pp. 85-90, England, November 1979.

[21] Mason, P.J., ''Effects of Air Entrainment on Plunge Pool Scour': American Society of Civil Engineers, Journal of Hydraulic Engineering, Vol. 115, No. 3, March 1989.

[22] Mendoza-Cabrales C., "Headwall Influence on Scour at Pipe Outlets': Thesis in partial fulfillment of the degree Master of Science, Colorado State University, April 1980.

[23] "Plunge Pool Performance Study; Project Data Review/Literature Search: Theodore Roosevelt Dam, Lower Colorado Region, Salt River Project, Arizona". Harza Engineering Co., March 1993.

[24] Spurr, K.J.W., ''Energy Approach to Estimating Scour Downstream of a Large Dam': Water Power and Dam Construction, July 1985.

[25] 'Tarbela Spillway Pool Erosion Prompts 100 Million Dollar Repair Job': Engineering News Record, Vol. 202, No. 1, p. 10, January 4, 1979.

[26] van Schalkwyk, A., "The Erodibility of Different Rock Formations in Unlined Dam Spillways", Report to the WRC on Pilot Investigation, August 1989, unpublished.

[27] Ruff, J.F., Abt, S.R., Mendoza, C., Shaikh, A., Kloberdanz, R. , "Scour at Culvert Outlets in Mixed Bed Materials", Federal Highway Administration, September, 1982.

[28] . Pit 4 Dam Stability Under Flood Loading and Dam-Break Analysis, FERC Project No. 233-CA, State of California Dam No. 97-100, Hydro Engineering and .Construction Dept., Pacific Gas & Electric Co., San Francisco, California, June, 1991.


f

[ r

l

u

u

I I I I I

Appendix B

Study Schedule

Dam Foundation Erosion Study Appendix B • 8-1

C

n C

0 J

._J

J

]

]

J

)

J

]

)

1

I .

'

-

&4 1995 1996 1997 1998 Task# Task List Duration Q3 IQ4 QI I Q2 I Q3 I Q4 QI I Q2 I Q3 I Q4 QI I Q2 I Q3 I Q4 QI I Q2 I Q3 I Q4

I Subcontracting 60d 1~ 2 Physical Modeling 680d IT T

3 1:3 Scale Model 195d iT

4 Construction 5d i• 6 Instrumentation Design 20d I 7 Clear Water Experiments 20d I 8 Interim Report 10d • 9 Temporal Experiments 30d • 10 Granular Material Experiments 30d • 11 Selected Material Experiments Od

12 Final Report/fhesis 35d ~~

13 1: I Prototype Model 637d T T

14 Construction 100d ~

15 Shakedown & Instrumentation Experime 12d [I

16 Clear Water Correlation Experiments 20d ~

17 Granular Material Correlation Experime 20d r2l

18 Interim Report 20d • 19 Cubical Elements Experiment 30d ~

20 Vertically Oriented Slab Experiment 30d • 21 Upstream Oriented Slab Experiment 30d • 22 Downstream Oriented Slab Experiment 30d • 23 Interim Report 20d ~

24 Cohesive Material Experiment 30d ~

25 Cohesive Material in Slab Joints Experi 30d • 26 Granular Material in Slab Joints Experi 30d •

Project: Criical ~ Props &mnary • • Date: 316195 Noncritical Miestone • RoledUp ()

3/6/95 Page 1 of 2 Dam Foundation Erosion - Schedule DFESCHED.MPP

94 1995 1996 1997 1998 Task# Task List Duration Q3IQ4 QI I Q2 I Q3 I Q4 QI I Q2 I Q3 I Q4 QI I Q2 I Q3 I Q4 QI I Q2 I Q3 I Q4

27 Other Experiments as Resources Allow Od • 28 Final Report/Dissertation or Thesis 90d -29 Numerical Model Development 636d "' "' 30 Specifications 20d I 31 Analysis 20d w 34 Flow Charting 20d I 35 Prototyping Phase I 120d

36 Prototyping Phase 2 120d ~

37 Alpha Testing 30d Im 38 Beta Testing 40d • 39 User Manual 120d ~

40 Version 1.0 20d ~

41 Final Report Compilation, Review, and Issue 65d • ... 42 Compilation 20d ~

43 Review 40d ~

44 Issue 5d I

Project: Criical ~ ~ 5"'rnary • • Oate:316195 Nonc:riical Miestone • Rolet!Up <)

3/6/95 Page 2 of 2 Dam Foundation Erosion - Schedule DFESCHED.MPP

Dam Foundation Erosio·n - Bureau of Reclamation Foundation Erosion Study Team Dam Foundation Erosio·n 1994 Year End Summary Report Study Team: Rodney J. Wittler, James F. Ruff, Steven

Documents