HomeMy WebLinkAboutMulti-Hazard Mitigation Plan: 11. DamFailures CIVIL DEFENSE AGENCY
COUNTY OF HAWAII
920 ULULANI STREET HILO,HAWAII 96720
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11. Dam Failures
Chapter 11:Hazard Analysis—Dam Failures
CHAPTER 11 - DAM FAILURES
11.1 Description of Hazard
The severity of flooding caused by dam breaks has been analyzed by modeling by the Pacific
Disaster Center and the US Army Corps of Engineers. Although no known dam break events
have occurred on Hawaii Island, the potential damage is significant enough to merit
prevention and disaster preparation. Dam failure can result from: prolonged periods of
rainfall; inadequate spillway capacity; internal erosion resulting in structural failure;
improper maintenance; improper design; negligent operation; failure of upstream dams on
the same watercourse; landslides into reservoirs which may cause surges resulting in
overtopping; high winds which can cause significant wave action resulting in substantial
erosion; and earthquakes,which cause longitudinal cracks and weaken the entire structure.
Hawaii County has 13 dams, all of which are earth dams.55 Most dams in Hawaii are old
earthen berm reservoirs built during the plantation era originally for irrigation purposes. Of
these dams, DLNR has rated two on this island to be "high" hazard based on the extent of
potential downstream losses to residential/ commercial structures or agricultural crops (see
Figure 11-1). A NASA-funded study applied a model to estimate flood losses.56 The report
classified the inundated area into three risk zones: the zone of severe flooding corresponds to
the region where flood depths are sufficient to cause severe structural damage or loss of life;
the zone of probable damage corresponding to the region that is expected to be flooded to a
depth of at least one foot; and the maximum possible flood extent. Because of the short
duration of such flooding events from a dam break, coupled with the unknown reliability of
the model, it would not seem practical to use the model for real time response. The value of
the modeling is to assess priority for preventive monitoring and maintenance rather than to
incorporate the results into the FIRM'S where it would be used for permitting and insurance
purposes.
55 Goosby,S.,Chatman,A.,Michaud,J.,Kerper,D.,Dam Break Inundation Study for the State of Hawaii,
Prepared for the State of Hawaii's Department of Land and Natural Resources,ASCE 2008
56 Johnson,C.and J.Michaud.Dam Failure Inundation Mapping Project,NASA Contract No.NASW-99044,
January 15,2003.
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Chapter 11:Hazard Analysis—Dam Failures
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Critical Dams
Dams
Figure 11-1. Dam Inventory and Rating
Following the 2006 Kiholo Bay Earthquake some damage occurred to dams and irrigation
ditches in the Waimea-Kamuela area where recorded peak ground acceleration exceeded 1.0g
(soil depths are greater in that region than along the rocky coast nearest the epicenter). At
least two dams experienced cracks along their crests, while at least two others showed clear
evidence of incipient slope failure on their embankments. The Pacific Disaster Center
performed dam break simulations for Hawaii County Civil Defense. Two dams located above
Waimea were drained after excessive seepage and "water boils" were observed five days
following the earthquakes. The State Department of Land and Natural Resources had in place
post-earthquake dam inspection procedures. The Hawaii Dam Safety Guidelines: Seismic
Analysis & Post-Earthquake Inspections (Brandes, 2004) call for inspections of dams within
75 miles of the source of an earthquake of magnitude between 6 and 7. The U.S. Army Corps
of Engineers undertook these comprehensive inspections.
The U.S. Army Corps of Engineers (USACE) provided Hawaii State Civil Defense (HSCD)
with completed documentation concerning the Statewide Dam Visual Conditions Survey in
response to the Kiholo Bay Earthquake on October 15, 2006. Documentation includes
electronic field inspection reports with corresponding photographs for 86 dams inspected by
USACE between October 30 and November 8, 2006. HSCD asked Pacific Disaster Center
(PDC) to develop a map viewer application to allow authorized users to view the
documentation provided by USACE. PDC created (and will maintain) a password-protected
map viewer that hosts and displays USACE data for persons authorized by HSCD to access
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Chapter 11:Hazard Analysis—Dam Failures
it. This map viewer is based on PDC's Hawaii Hazards and Vulnerabilities Atlas, which was
also used as the foundation for the Critical Infrastructure Protection (CIP) Map Viewer and
other PDC-developed applications. In addition to the existing functionality contained within
these viewers, the Dam Status Map Viewer includes "hot links" to "State of Hawaii DLNR
Dam Safety Inspection Sheets" for each dam as well as to site graphics as available. A list of
all dams on the Island of Hawaii is included below.
1. HA00026 Lalakea Reservoir
2. HA00051 Hawi No. 5 Reservoir
3. HA00027 E-13 Reservoir
4. HA00052 Kehena Reservoir
5. HA00040 Waikoloa 50 MG Reservoir
6. HA00122 Waikoloa 50 MG Reservoir 2
7. HA00042 Puukapu Reservoir
S. HA00123 Puu Pulehu Reservoir
9. HA00043 Puukapu Watershed Retarding Dam R-1
10. HA00131 Paauilo Reservoir
1 l. HA00049 Keaiwa Reservoir
12. HA00136 Waikoloa 50 MG Reservoir 3
13. HA00050 Hawi No. 3 Reservoir
11.2 Significant Historic Events and Lessons Learned
There is no record of any major dam failures on the Island of Hawaii resulting in significant
loss of property or life. However, as discussed previously several dams showed signs of
damage following the Oct. 2006 Kiholo Bay earthquake.
On March 14, 2006, just before dawn, Ka Loko Dam on the island of Kauai breached
sending nearly 400 million gallons of water (weighing 1.6 million tons) from the Ka Loko
Reservoir into Kilauea Bay, taking trees, cars,buildings, and seven human lives with it.
According to Godbey's independent civil investigation of the Ka Loko Dam failure, the
breach of the dam can be attributed several possible conditions and practices. Among these
conditions and practices are inadequate inspection of the dams by the State of Hawaii, non-
permitted grading operations at the dam site by the owner, inadequate maintenance of the
dam by the owner, and non-enforcement of regulations by the County of Kaua`i.57
57 Godbey,Robert,Report of the Independent Civil Investigation of the March 14,2006 Breach of Ka Loko
Dam, 1,January 2007
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Chapter 11:Hazard Analysis—Dam Failures
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Figure 11-2 Shaded Relief of Ka Loko Dam and Vicinity,Island of Kaua`i58
5'Godbey,Robert,Report of the Independent Civil Investigation of the March 14, 2006 Breach of Ka Loko
Dam, 1,January 2007
11-4 Hawaii County Multi-Hazard Mitigation Plan
Chapter 11:Hazard Analysis—Dam Failures
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Figure 11-3 Ka Loko Dam Breach,Island of Kauai-9
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Figure 11-4 Ka Loko Dam Breach,Island of Kaua`i6O
59 Godbey,Robert,Report of the Independent Civil Investigation of the March 14,2006 Breach of Ka Loko
Dam, 1,January 2007
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Chapter 11:Hazard Analysis—Dam Failures
Figure 11-5 Houses Amid Debris from Ka Loko Dam Failure,Island of Kaua`i61
Figure 11-6 Road Infrastructure Damage from Ka Loko Dam Failure,Island of Kaua'i62
60 Image Retrieved Wikipedia Website October 26,2009 from
http://en.wikipedia.org/wiki/File:Kaloko breach.j pg
61 Image courtesy of Hawaii Department of Land and Natural Resources(DLNR),Star Bulleting Website,
Retrieved October 26,2009 from http://archives.starbulletin.com/2006/03/15/news/stor101.html
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Chapter 11:Hazard Analysis-Dam Failures
11.3 Probability of Occurrence
Given the increased monitoring procedures enacted following the breach of the Ka Loko
Dam on Kauai, the probability of a dam failure anywhere in the state of Hawaii has been
significantly reduced. A major dam failure is a very rare event for which there is no defined
recurrence interval. However, the potential does exist during an extreme rainfall event, or
major earthquake at any unmaintaincd or under maintained location.
11.4 Risk Assessment
After the failure of the Kaloko Dam, the DNLR Dam Safety Division initiated a project to
study the potential inundation areas downstream of all 135 registered dams in Hawaii. The
failure scenarios considered were:
• Sunny day failure with dry downstream conditions
• Failure occurs when dam is at maximum capacity
• Failure occurs by piping failure halfway up the dam face
• Spillways and dam outlet works are inoperable at the time of the breach
The water flow from the dam failure scenarios was modeled to determine maps of the
inundation area, maximum water depth, maximum flow velocity and time of inundation at
each dam. The various impacts of the dam break were considered for each dam, including:
• Impact to the population by the number of people potentially impacted downstream
• Impact to transportation including water depth and speed at bridges and road
crossings
• Impact to buildings based on replacement cost value
• Impact to critical facilities including schools, hospitals, fire and police stations,
government buildings, airports/seaports, shelters
The results of this study could be used to infer some type of expected annual loss based on a
probability of a particular dam's failure, however, these probabilities very small and ideally
zero if proper monitoring and maintenance is provided. The intention of this study was
prioritize critical areas, and to provide a reasonable assessment of risk, not to determine
annual expected losses for comparison with other hazards.
11.5 Mitigation Strategies
11.5.1 General
11.5.1.1 National Dam Inspection Act
The National Dam inspection Act (NDIA) of 1972 as expressed in Public Law 92-367
authorized for the first time the federal regulation of privately own dams. Per the NDIA, the
United Sates Army Corps of Engineers (Corps) were authorized to inventory and inspect
privately owned dams in the United States. The NDIA provided funding for the Honolulu
62 Image courtesy of Casey and Cyndi Riemer from Jack Harter Helicopters,Retrieved from Star Bulletin-,
Website on October 26,2009 from http://archives.starbulletin.com/2006/03/15/news/stoKyOl.html
11-7 Hawaii County Multi-Hazard Mitigation Plan
Chapter 11:Hazard Analysis—Dam Failures
Army Corps of Engineers and the State of Hawaii Department of Land and Natural
Resources (DLNR) to complete an inventory of dams in the State of Hawaii and perform
inspections of 53 high-hazard private dams between 1977 and 1981.63
11.5.1.2 National Dam Safety Program Act
The purpose of the National Dam Safety Program Act (NDSPA) of 2000, as expressed in
Section 215(a) of Public Law 104-303, is to "reduce the risks to life and property from dam
failure in the United States through the establishment and maintenance of an effective
national dam safety program to bring together the expertise and resources of the federal and
non-federal communities in achieving national dam safety hazard reduction."
The State assistance program is intended to help States bring the necessary resources to bear
on inspection, classification, and emergency planning for dam safety. Public Law 104-303
provides for the assistance program described below.
For a State to be eligible for primary assistance under the National Dam Safety Program, the
state dam safety program must be working toward meeting the following criteria, as listed in
Public Law 104-303:
• The authority to review and approve plans and specifications to construct, enlarge,
modify,remove, and abandon dams;
• The authority to perform periodic inspections during dam construction to ensure
compliance with approved plans and specifications;
• A requirement that state approval be given on completion of dam construction and
before operation of the dam;
• The authority to require or perform the inspection at least once every 5 years of all
dams and reservoirs that would pose a significant threat to human life and property in
case of failure to determine the continued safety of the dams and reservoirs, and a
procedure for more detailed and frequent safety inspections;
• A requirement that all inspections be performed under the supervision of a state-
registered professional engineer with experience in dam design and construction;
• The authority to issue notices, when appropriate, to require owners of dams to
perform necessary maintenance or remedial work, revise operating procedures, or
take other actions, including breaching dams when necessary;
• Regulations for carrying out the legislation of the state;
63 Office of History,United Sates Army Corps of Engineers,The Federal Role in Water Resources
Management„Washington,D.C., 1896, 12p
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Chapter 11:Hazard Analysis—Dam Failures
• The provision for funds to ensure timely repairs or other changes to or removal of a
darn to protect human life and property, and if the owner of the dam does not take the
action described above,to take appropriate action as expeditiously as possible;
• A system of emergency procedures to be used if a dam fails or if the failure of a dam
is imminent; and
• An identification of each dam whose failure could be reasonably expected to
endanger human life, the maximum area that could be flooded if the dam failed, and
public facilities that would be affected by the flooding.
11.5.1.3 State ofHawai`i Dam Safety Act
The State of Hawaii Dam Safety Act was started in 1987 where the rules, statues, and
Hawaii Administrative Rules were set up by the Department of Land and Natural Resources
(HAR, Title 13, Subtitle 7, Chapter 190, Dams and Reservoirs). A majority of existing dams
were built by private plantation owners in the early 1900's for irrigation and not flood
control; there were no standards at that time. According to the Hawaii National Flood
Insurance Program (NFIP) Certified Floodplain manager (CFM), during that historical
period, when the embankments were built, workers had carts filled with rocks that were
pulled by horse or mule, which then ran back and forth over the embankment to provide
some compaction.
The Department of Land and Natural Resources(DLNR) Engineering Branch administers the
Hawaii Dam Safety Act The DLNR reviews and approves plans and specifications for the
construction of new dams or for the enlargement, alteration, repair, or removal of existing
dams. Any individual or entity seeking to construct, alter, or remove an existing dam must
fill out the "Application For Approval Of Plans And Specifications For Construction,
Enlargement, Repair, Alteration, Or Removal Of Dam" with the DLNR Engineering Branch,
Dam Safety Section.
11.5.2 Previous/Current Efforts
11.5.2.1 United States Army Corps of Engineers Statewide Dam Visual Conditions Survey
Following the 2006 failure of the Ka Loko dam in the island of Kauai, the State of Hawaii
DLNR in coordination with the Corps conducted emergency visual inspections of dams on
the islands of Kauai, Oahu, Molokai, Maui, and Hawaii. The purpose of the inspections
was to assess whether there existed any imminent danger to life and property based on the
dam and/or reservoir conditions at the time of the inspection. DLNR determined that this
broad-based visual inspections were sufficient basis for the State of Hawaii to contact dam
owners for follow-up investigations and potential remedial and/or mitigatory actions. All
statewide inspections pertaining to this initiative are consolidated into a report titled
"Statewide Dam Visual Conditions Survey for the islands of Maui, Oahu, Hawaii, and
Molokai and re-inspections on the island of Kauai" dated June 23,2006.
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Chapter 11:Hazard Analysis—Dam Failures
The dam inspections consisted of the visual only examination or condition survey of the
regulated dam structures, including abutments, spillways, outlet facilities, and reservoir. The
visual assessments yielded conditions ratings that ranged according to the following:
• Satisfactory: Dam is expected to fulfill its intended function.
• Fair: Dam is expected to fulfill its intended function but maintenance is
recommended.
• Poor: Dam may not fulfill its intended function and maintenance/repairs are
necessary.
• Unsatisfactory: Dam is not expected to fulfill its intended function and repair,
replacement, of modification is necessary.
• Unknown: Dam is not visible, not accessible, not inspected, or unable to determine
the condition rating based on the observation taken.
Besides the rating, the report includes recommendations for each facility if any. Typical
recommendations vary from the removal of vegetation to facilitate future inspections to the
requirement of owners to make immediate repair actions to restore the integrity of the
facility.
A total of thirteen dams were inspected in the County of Hawaii. Full summary reports of
these inspections can be found at http://www6.hawaii.)4ov/dlnr/reports/dam-inspections/.
11.5.2.2 Pacific Disaster Center Dam Failure Inundation Map Project
In 2009, the State of Hawaii DLNR and the Pacific Disaster Center (PDC) engaged in an
effort to generate Dam Failure Inundation Maps for all one-hundred-thirty-five (135)
registered dams in the State of Hawaii. Besides the inundation maps, the project aims at
providing basic damage assessment and social-economical vulnerability assessment.
The inundation maps for this project were produced using MIKE software—one of the
industry standards for simulating flow and water level,water quality and sediment transport
in rivers, floodplains, irrigation canals,reservoirs, and other inland bodies of water. All three
available modules of the MIKE Modeling Suite were used to substantiate the results of the
analyses: MIKE 11 for one-dimensional dynamic modeling of river, channel, and reservoir
hydraulics; MIKE 21 for two-dimensional free surface flow models; and MIKE FLOOD for
the integration of a series of dams within one single model. For illustration purposes,
inundation maps for the same dam based on the two- and three-dimensional modeling
capabilities of MIKE 1 1 and MIKE 21 are shown in Figure 1 1-7. Similarly, Figure 1 1-
illustrates a single model of a series of dams using MIKE FLOOD.
The following failure scenarios and assumptions were use to assure conservatism in the
preparation of the maps:
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Chapter 11:Hazard Analysis—Dam Failures
• Failure occurs during a sunny day with dry downstream conditions
• Failure occurs when dam is at its maximum capacity
• Failure occurs by piping failure halfway up the face of the dam
• Spillways and dam outlets are inoperable at the time of the breach
In addition to the dam failure inundation maps, the study will provide individual dam
assessment reports with the following information:
• Total maximum water depth
• Time of maximum water depth
• Time to first inundation
• Depth at first inundation
• Water velocity.
• Impact to population including number of people potentially impacted downstream
• Impact to transportation including water depth and velocity at bridges and road
crossings
• Impact to building infrastructure and replacement cost value
• Impact to critical facilities (schools, hospitals, fire and police stations, government
buildings, airports/seaports, and shelters)
As of the third trimester of 2009, PDC has completed the dam failure inundation maps and
individual assessment reports for all one-hundred-thirty-five (135) dams. In 2010, DLNR
evaluated and approved these maps and reports for release to County of Hawaii Civil
Defense, for official use only. The Hawaii County Police Department, responsible for
evacuation procedures, utilized the reference dam inundation maps to develop potential dam
break evacuation maps. An example map for the Waimea area(and downstream) is shown in
Figure 11-9. It is expected that the documents will be released to the public in early 2011.
11-11 Hawaii County Multi-Hazard Mitigation Plan
Chapter 11:Hazard Analysis—Dam Failures
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Figure 11-7.Comparison of One-Dimensional(MIKE 11)&Two-Dimensional(MIKE 21)Dam Failure Modeling64
RESERVOIR-
�. AEPOALUA RESERVOIR
AEPOKOLU f;ESERVOIR
f
AEPOEFIAR SERVOIR 1
MIKE • •
Figure 11-8.Serial Dam Failure Modeling using MIKE FLOOD 61
64 Goosby,Stanley,Chatman,Andrea,Michaud,Jene,and Kerper,Dale,Dam Break Inundation Study for the
State of Hawaii,American Society of Civil Engineers(ASCE)Conference Proceedings,2008,312,40p
65 Goosby,Stanley,Chatman,Andrea,Michaud,Jene,and Kerper,Dale,Dam Break Inundation Study for the
State of Hawaii,American Society of Civil Engineers(ASCE)Conference Proceedings,2008,312,40p
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Chapter 11:Hazard Aualyus—Dam Failures
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I I I C N
I S A ST E R Sunny Day Piping Failure of Waikoloa#2 Reservoir(H1001 36)at 61.9 million gallons A
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Mil
0.8 1.2 1.8 2.4 3
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0.125 0.25 0.25 0.5 1
Fire Stations Dams
j Public Schools Evacuation Zone
QPolice Stations - .. Perennial Streams
* Emergency Shelters
Imagery:(c)Quick Bird 2009 Senes dam failure scenario considers Mat Waikoloa#2 fails by piping This product depicts downstream flood
and rows into Me lower dams which fail by overtopping. potential using Me DMI MIKE 21 model.
June 30,2010
Figure 11-9 An example map of the Waimea area(and downstream)
utilizing reference dam inundation maps to develop potential dam break evacuation maps.
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Chapter 11:Hazard Analysis—Dam Failures
11.5.3 Future Plans
Project Description Status
Dam&Reservoir Safety DLNR Evaluation; DWS repair of Kibolo
Drafting of Dam Safety Guidelines USCOE dam break intmdation study Bay earthquake damage
Permitting requirements for new dam of 11 dams statewide completed; at Waikoloa
construction PDC study of"sunny day"dam DLNR Engineering
Certification of compliance that owners break inundation for 138 dams Division is completing
meet Phase I operation and maintenance statewide completed;dam break Phase I Detailed Visual
recommendations and have an emergency evacuation maps being finalized in Inspections,and
action plan. December 2010 by Hawaii County updating the state dam
Civil Defense Agency inventory C-122.
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