SPECIALTY WORKSHOP: SITES TRAINING AND INTRODUCTION TO WINDAM ASDSO Dam Safety 2008

1. PART 2 – SITES EARTH SPILLWAY EVALUATION B. Earth Spillway Integrity Analysisb. Characterization of geologic materials: iii. Characterizing the Headcut Erodibility Index (Kh) 2) for Cohesionless Soils SPECIALTY WORKSHOP: SITES TRAINING AND INTRODUCTION TO WINDAM ASDSO Dam Safety 2008

2. Objectives • State the common range of the Kh parameter for soils • Identify plot of rate of headcut migration versus Kh parameter and explain sensitivity of plot to values of Kh • Using example soil data, assign a value to the Kh parameter accurately • Identify tests used to characterize soils for estimating the Kh parameter

3. Typical values for the KhFactor 0.01 Soil 0.2 Weathered Rock 0.5 Soft or Jointed Rock 10 Hard Rock

4. Available Tools For Estimating Kh • NEH 628, Chapter 52, Appendix B • Soil Catalog on SITES CD

5. Chapter 52, Appendix B - Soils • If the PI greater than 10 – Cohesive • If the PI is < 10, soil is Cohesionless

6. Soil Weathered Rock Poor Quality Rock 0.2

7. Available Tools For Estimating Kh • Spreadsheet • Uses soil properties from field and laboratory tests or table estimates • NEH 628, Chapter 52, Appendix B • Soil Catalogue

8. Examples of Catalog Soils • Catalogue Soils are on SITES CD

9. Soil Catalog • Existing catalog for soils (assuming that Kh value is < 0.2) is ten samples • Only Three Cohesionless Soils. • Catalog listings with Kh values of 0.01 to 0.03 for cohesionless soils • Experience with recent Oklahoma spillway shows Kh values may be less than 0.01 for nonplastic non-cemented sands.

10. Soil Catalogue • Soil descriptions are very brief • Some wording confusing – example index value based on laboratory strength notation for nonplastic ML soil from Oklahoma

11. Only Three Cohesionless Soils in Catalogue

12. Kh – 0.01 Buck and Doe Run 33, MO SM, very loose sand with little bonding;deep deposit

13. Kh – 0.02 Rush Creek 45, Oklahoma ML, cohesionless, headcut; index value based n laboratory strength test

14. Chapter 52, Appendix B • Is the PI greater than 10 – Cohesive • If the PI is < 10, soil is Cohesionless Following summary next discusses cohesionless soils

15. Kh – 0.03 Big Sand 3, MS ML, some apparent bonding; headcut

16. Material Strength Number, Ms • For Cohesionless Soils • Values for Kh and Ms are related to relative density estimates and SPT values (Table 52-2)

17. Table 52-2. Ms for Cohesionless Soils

18. Relative Density Very Loose Loose Medium Dense Very Dense Field Estimates for Relative Density • Description • 1/2” Reinforcing rod can be pushed easily by hand into soil

19. Relative Density Very Loose Loose Medium Dense Very Dense Field Estimates for Relative Density • Description • Can be excavated with a spade. A wooden peg 2”x 2”can easily be drive to depth of 6 ”.

20. Relative Density Very Loose Loose Medium Dense Very Dense Field Estimates for Relative Density • Description • Easily penetrated with a 1/2” reinforcing rod driven with a 5 pound hammer

21. Relative Density Very Loose Loose Medium Dense Very Dense Field Estimates for Relative Density • Description • Requires a pick for excavation. Wooden peg 2”x 2”is hard to drive beyond 6 ”.

22. Relative Density Very Loose Loose Medium Dense Very Dense Field Estimates for Relative Density • Description • Penetrated only a few centimeters with a 1/2” reinforcing rod driven with a 5 pound hammer

23. Other estimates for relative density • Estimate Relative Density from SPT tests • Field Tests – Based on Reinforcing Rod and Wooden Stake • Dynamic Cone Penetrometer

24. Dual Mass Dynamic Cone Penetrometer

25. very dense – Kh > 0.20 Dense – Kh = 0.10 – 0.20 Medium – Kh = 0.05 – 0.10 Loose – Kh = 0.02-0.05 very loose – Kh < 0.02

26. Summary • The rate of upstream migration of a headcut predicted by the SITES program is extremely sensitive in the range of values of the Kh parameter which are typical for soils • Cohesionless soils (PI < 10) have typical values of Kh less than 0.05