This document summarizes the final phase of the San Clemente Dam removal and stream restoration project in California. It describes the project location and history, provides an overview of key stakeholders and the project schedule, discusses the regional and site geology, and details the final design elements and construction phases. These included building a diversion dike, stabilizing sediment slopes, constructing a combined flow reach with step pools, removing the dam, and installing instrumentation to monitor slopes, embankments, and settlement. The project successfully removed an aging dam to restore fish habitat while mitigating geological hazards through engineering and post-construction monitoring.

1. The Final Phase of San Clemente Dam –
Removal and Stream Restoration
Godwin, W. , Waeber, J. , Wade, D, and McGowan, W
Annual Meeting, Association of Environmental &
Engineering Geologists– Kona, Hawaii
September 21, 2016 Technical Session #1
Presented By:
William Godwin, P.G., C.E.G.

2. 2
Outline
Project Location and History
Project Overview
Geology
Final Design Elements
Final Construction Phases
Dam Removal(s)
Instrumentation and Monitoring
Questions

3. 3
Project Location

4. 4
History of San Clemente Dam
Constructed between 1920
& 1921 by PIC
Owned and operated by
California American Water
Built for drinking water
storage for Monterey
Peninsula
Fish ladder added later

5. 5
Built in V-notch canyon
below confluence of San
Clemente Creek and
Carmel River
Concrete arch dam
106 feet high
300 foot width
1425 acre-feet – now 70
acre-feet
Over 2.5 million cubic yards
of sediment
History of San Clemente Dam

6. 6
Project Overview

7. 7
Project Overview
1990’s CDWR – DSOD issued safety order
Potential failure during MCE (7.0M Tularcitos fault) or PMF
2006 released a draft EIS
EIR Alternatives:
Dam Strengthening ($50M)
Dam Removal
2008 CAW – preferred removal of the dam. Benefits: fish
access, sediment replenishment, removal of hazard
Previous investigations by URS, MWH, Woodward-Clyde
and Kleinfelder
URS provided an indicative design

8. 8
Combined Flow Reach
Upper San Clemente Creek
Reroute Channel Sediment
Stockpile
Upper Carmel
River Reach
Former Location
Of Dam
Diversion Dike
Stabilized
Sediment
Slope
Project Overview - Layout

9. 9
Project Overview – Key Stakeholders
$83M cost
Funding: California
American Water
California Department of
Fish & Wildlife
California Natural
Resources Agency
California Wildlife
Conservation Board
California State Coastal
Conservancy
National Marine Fisheries
Service – NOAA
Resources Legacy Fund
The Nature Conservancy
United States Fish &
Wildlife Service

10. 10
Project Overview – Project Team/Schedule
Granite Construction –
General Contractor
Kleinfelder – Engineer of
Record (EOR) and lead
Civil/Geotechnical designer
Tetra Tech – H/H modeler,
Channel Restoration design
Rana Creek, Habitat
Restoration
Oversight
AECOM – Owners Engineer
WSC – Construction Mgr.
2013 Season:
Geotechnical
Investigation, initial
diversion structures,
overall design
2014 Season: Reroute
Cut, Diversion Dike,
Sediment Stockpile,
design/construct
2015 Season: Stabilized
Sediment Slope, dam
removal, CFR channel
design/construct

11. 11
Regional Geology
Jennings 2010

12. 12
Site Geology
History of Dam
Project Background
Project Overview
Geology of Location
Geotechnical Investigation
Challenges
Summary
Dibblee, T.W., and Minch, J.A.,“Geologic map of the Carmel Valley quadrangle, Monterey County, California,” published by Dibblee Geological
Foundation in 2007,
Accessed from http://ngmdb.usgs.gov/Prodesc/proddesc_83298.htm
Lt Mesozoic
Granodiorite
Lt Mesozoic
Granodiorite
Early Mesosoic
Metasedimentary
& Granitic Rocks
Lt Mesozoic
Quartz Monzonite
Miocene
Sandstone
Lt Mesozoic
Quartz Diorite
Early Mesosoic
Metasedimentary
& Granitic Rocks

13. 13
Combined Flow Reach
Habitat Restoration
Upper Carmel
River Reach
Dam Demo Plan
Stabilized
Sediment
Slope
2015 Final Design
Elements

14. 14
Diversion Dike (DD) Design

15. 15
Stabilized Sediment Slope (SSS) Design

16. 16
Combined Flow Reach (CFR) Design

17. 17
CFR Design – Step Pool Plan

18. 18
CFR Design - Step Pool Elevation

19. 19
Construct Combined Flow Reach
Restore San Clemente Creek
Reroute Rock Sill
Top off Sediment
Stockpile
Grade Upper Carmel
River Reach
Remove Dam and
Slide Debris
Remove Diversion Pipe and Cutoff
Complete
Stabilized
Sediment
Slope
2015 Final
Construction
Elements
Final Reservoir Drain

20. 20
Construction – Christmas Slide/pipe repair
Dec. 2014 landslide; Mar. 2015
debris removal and pipe repair
June 2015 right abutment and
diversion pipe

21. 21
Construction – Reservoir Dewatering

22. 22
Construction - Diversion Dike (DD)
October 2014 view NE October 2015 view SW

23. 23
Construction – Reroute Channel Rock Sill

24. 24
Construction – Reroute Channel Rock Sill

25. 25
Construction – SSS foundation mapping
Toe of SSS Transition beneath SSS

26. 26
Construction – Geologic Strip Mapping
Potential for catastrophic landsliding and stream blockage

27. 27
Evaluation – Catastrophic Landslide Risk
Geologic Map
of Combined
Flow Reach.

28. 28
Failure of CFR valley ways leading to stream
blockage due to runout.
Evaluation Methodology:
Inputs:
Geologic data (borehole, strip mapping, GSI, RMR)
Scour Analysis (1000 flood event WSE, Erodibility Index K)
Slope Stability (Kh = 0.2 (1/2 of pga)
Analysis: Scour by Annandale (1995) of Required
Stream Power vs K; Rock Mass Erodibility Index;
Limit Equilibrium method for Slope Stability
Evaluation – Catastrophic Landslide Risk

29. 29
Evaluation – Catastrophic Landslide Risk
Geomechanical Model,
Section 2
Pseudostatic Analysis,
Section 2

30. 30
(De) construction – dam removal
Upstream Ramp and use
Pneumatic hammer
Recycle rebar, bury
concrete in SSS
Sigh…..No Explosives

31. 31
(De) construction – DSOD Concerns
Left Abutment Rockfall Right Abutment Stability

32. 32
Boulders for CFR Pools - Material Testing
“Drop Test” at various quarries to measure durability.
Eventually used mostly concretions from two quarries in
Livermore valley

33. 33
Construction – CFR pool construction
Step Pool sequence Field Supervision

34. 34
Instrumentation installation and monitoring
Slope inclinometers (SI) along former reservoir rim and top
of engineered embankments
Time Domain Reflectometers (TDR):
Deformation at depth
No magnitude
Reflective Survey Monuments:
All over slope
Measured biannually
Vibrating Wire Piezometers
Instrumentation data collection

35. 35
Instrumentation installation and monitoring
TDR for Reroute, Left Slope Slope Inclinometer for SSS

36. 36
Removal of 1883 Old Carmel River Dam

37. 37
Sleepy Hollow Ford Bridge Construction

38. 38
Slope stability and erosion reconnaissance
Instrumentation measurements (Slope Inclinometer, VWP, TDR and
surface settlement markers)
Additional monitoring via Triggering Events
- 4.0M EQ w/in 50 miles
- 10yr flood event (>3,600 cfs)
Habitat die-off/ replacement
Win-win for everyone
Dam removal for safety
Restore ecological balance
Turnover to BLM
Path Forward – 5 year monitoring period

39. 39
Acknowledgements
Aman Gonzalez - California American Water
Brian Hussar – Granite Construction Company
Craig Hall, GE – GEI
Morley Beckman, PE – Kleinfelder
Jeff Richmond, CEG – Kleinfelder
Kami Deputy, PE – Shannon & Wilson
Merideth Beswick, PE, GIT - Kleinfelder

40. 40
QUESTIONS?