POSTED 31 MARCH 2006 - 4:00pm HST

Design of Small Dams

illustration of cross section of earthfill dam at high and low water levels from "Design of Small Dams"

by Juan Wilson 0n 31 March 2006

My wife recently bought me a book from the Talk Story Bookstore that I have been thinking about getting for a couple of years.It was marked at $70 and seemed a high price to pay. The book is "Design of Small Dams" published by the United States Department of the Interior.

The book is essentially an engineering manual for designing small earth and rock dams.Well, in the wake of the failure of the Ka Loko Reservoir we revisited the store and, after being offered a discount, we went home with the book. Incidentally, we later checked the web and found offered the book for $99. We got a good deal.

The book is not new. It was revised in 1977 and incorporates the engineering knowledge only unto that time. However, the book is still a very useful guide on the design of a number of kinds of dams, including earthfill dams for irrigation reservoirs.

The introduction to Chapter 6: Earthfill Dams was written by H. G. Arthur and says in part.

Earthfill dams for the storage of water for irrigation, as attested both by history and the surviving remnants of ancient structures, have been used since the early days of civilization. Some of the structures built in antiquity were of considerable size. One earthfill dam eleven miles long, seventy feet high, and containing about seventeen million yards of embankment was completed in Ceylon in 504B.C. ...

Until modern times all earthfill dams were designed by empirical methods, and engineering literature is replete with accounts of failures. These failures compelled the realization that the empirical methods must be replaced by rational engineering procedures in both design and construction. One of the first to suggest that the slopes of earthfill dams be selected on that basis was Bassel in 1907.

However, little progress was made on the development of rational design procedures until the 1930's. Their rapid advancement of the science of soil mechanics since that time has resulted in the greatly improved procedures for the design of earthfill dams. These procedures include (1) thorough preconstruction investigations of foundation conditions, (2) applied engineering to design, (3) controlled methods of construction. ...

Failures of small earthfill dams, however, continue to be commonplace.


One thing this tells me is that if the the major reservoirs on Kauai were built before 1930 they were built using empirical knowledge that predates the "rational" engineering only developed subsequently. It is unlikely that the Hawaii Department of Land & Natural Resources has the historic knowledge of exactly how those dams were built; their assurances of safety not-with-standing.

I think that a prudent thing to do would be to reduce the volume of some of the larger reservoirs by lowering their spillways. This would decrease the likelihood of future massive failures, while continuing to provide water for agriculture.



The danger may not be over yet!

22 March 2006 - 8:15am

aerial image of lip of Ka Loko Reservoir failure taken by Jack Harter Helicopters

Unstable Soil Likely Danger for Some Time
by Juan Wilson on 22 March 2006

I don't claim to have expertise in soil dynamics or hydrology, but I have watched erosion and breaks in soil due to runoff on a small scale along the shore and in the valleys of Kauai.

After examining aerial photos of the course of the Wailapa Stream and after interviewing a resident living immediately below the dam failure, I've come to the conclusion that there will likely be subsequent danger to people and the properties downstream from the Ka Loko Reservoir for some time to come. The valley of the stream is as deep as 75 feet in some places.

In many areas the 300 million gallons of water that raged down the Wailapa Stream cut vertical walls along the banks of the valley. In some places the torrent washed plants and earth away down to bedrock. In many spots the water cut through deep soil leaving undercut walls, tall cliffs of red earth and what will likely be conditions that will create mud slides, serious erosion and dangerous situations for years to come.

The natural repose of un-reinforced soil is about a 100 percent grade (45 degree angle). It is seems likely to me that as following rains saturate the ground, and slice through the embankments with runoff, that the side walls of the Wailapa Stream will calve off large chunks of soil. I predict this action will continue until the natural angle of repose can be achieved and plants can assert themselves again to reinforce the banks.

I think that when the unstable sidewalls of the Wailapa Stream collapse they may create situations that create temporary small dams that backfill with storm water and lead to later small flooding situations downstream.

This could be particularly dangerous for hikers or others in the valley. I think this could also be dangerous on the high ground above the stream near the embankments. Even moderate loads of something like a moving vehicle along the edge of an embankment that used to be safe, could have disastrous results.

I recommend that some testing be done to determine the risks involved and that frequent inspections be made until the danger of aftermath embankment failures subsides. The State and County may already have made these considerations, but I know that some local property owners have not, and may but themselves danger.



A layman’s analysis

22 March 2006 - 8:00am

The rains of February and March, 2006
by Ray Chuan on 22 March 2006

The island of Kauai is known for its abundance of rainfall, especially during the winter and spring months. The scores of reservoirs built up to hundred years ago have always served their agricultural purposes well, from the glory days of big sugar down to contemporary small organic produce farms. What then was the difference between the rainfalls of the past decades, year after year, without a breaching of the dam of a large reservoir, and the rains of the past month (late February to mid March of 2006) that presumably led to the breaching of the dam at the Ka Loko Reservoir during the early hours of March 14?

Leaving aside for now the question of whether human failings may have contributed to the failure of the Ka Loko Dam, I would suggest that we might look at the pattern of rainfalls during the period from mid February to mid March. Since there is no particular single rain gage somewhere in the northeastern part of the island that alone can represent adequately the bulk of the rains that fell during this period, I suggest the flow rate in the Hanalei River probably serves the purpose of representing the larger rainfall pattern over the northeastern part of Kauai, because a significant part of the rain that falls on the center of the island that flows out of the open north-facing opening of the central crater goes down
the Hanalei River, especially since the discontinuance of the by-pass tunnel that for many decades diverted a large part of the flow leaving the central crater that
would have flowed naturally down the Hanalei River, instead, to the Wailua Watershed. The figure below shows the water flow rate, in cubic feet per second,
down the Hanalei River for the period February 20 to March 18: We see in this plot six significant high flow events from February 20 to March 18, with the highest peak flow during the night of February 21 of 15,000 cubic feet per second. To appreciate this flow rate one should compare with the fact that during the spring season when rafting down the Grand Canyon is a great sport the Park shuts down rafting when the flow rate reaches 15,000 cuft per second!

This was presumably the high rainfall event that took place in the upper reaches of the Moloa`a Stream that destroyed a bridge on a government road. Exactly what the source above that produced the higher than normal flow on this stream is apparently still in dispute.

Suffice it to say that, judging by the topography of the area, the flow must have come down from somewhere on the near-plateau at 680 ft elevation where the Ka
Loko Reservoir is located. State Department of Health personnel who inspected Ka Loko Reservoir after the report of the bridge destruction reported seeing no
breach in the dam.

The next event, which caused a peak flow of 3,000 cuft per second in he Hanalei River, took place a week later, on the night of February 27, which apparently did not cause any reported severe flooding. Nor did the next two significant events on March 2 and March 10. However, these two events, while peaking at much lower flow rates compared to the February 21 event, lasted much longer and undoubtedly put significant amounts of water in various reservoirs in the general
area, including Ka Loko.

Then came the event in the early hours of March 14, which caused the Hanalei River flow to rapidly peak at 7,000 cuft per second; which apparently was the straw that broke the camel’s back, causing the dam at Ka Loko to breach, sending a wall of water from 680 ft elevation down to Kuhio Highway at about 280 ft, a drop of 400 feet in two miles distance, while completely over-flowing the Morita Reservoir on the way, eventually reaching the ocean in Kilaue Bay in
another three quarter mile.

The three-day lapse to the next event, represented by the peak flow rate of 5,000 cuft per second in the Hanalei River, apparently added no significant damage,
since Ka Loko by then had been substantially drained; and Morita Reservoir by itself could not have contributed any over-flow anywhere near close to that
associated with the breaching of Ka Loko on the 14th.

Granted that the state has not enforced its rule regarding the care and monitoring of reservoirs on this island; but the added lesson to be learned from this catastrophic event of March 14, 2006 seems to be that when there is a close succession of major rainfall events, each one of which by itself might not
create a serious flooding event, close monitoring of the larger reservoirs over a short period may well be the best policy to pursue.



22 March 2006 - 7:45am

Dam Safety: A Quiet Crisis
by Neil
Abercrombie on 19 March 2006
Hawaii was shocked by the Ka Loko Dam tragedy on Kaua’i, with its loss of life, years of work destroyed and an entire community disrupted. The state rallied quickly on behalf of our Kaua’i ohana. Search and rescue teams swung into action. Other responders lost no time in caring for survivors, restoring services and mitigating dangerous conditions.

Ka Loko focused public attention on a deeper question we seldom think about until tragedy strikes: What are our government officials doing to keep our communities safe from dam failures? As a general rule, property owners are responsible for maintaining the safety of dams located on their land. State governments are responsible for the inspection of dams (except those owned by the Federal government) within their jurisdictions.

However, Congress has an important role in authorizing Federal assistance for dam safety. I have been pressing for Congress and the Federal government to take a more active role in this effort: • Last November, I cosponsored the Dam Rehabilitation and Repair Act of 2005 (H.R. 1105), which authorizes $350 million in Federal grants to states over a four-year period. The grants would cover up to 65 percent of the costs of repair, replacement, reconstruction or removal of unsafe dams. • I am also cosponsoring another bill (H.R. 4226) focused specifically on small privately-owned dams like Ka Loko. It would authorize the Federal government to pay up to 65 percent of the cost of removal or repair of privately owned dams, with a $5 million cap on Federal funds for any one project. The program would not cover dams used to generate power.

In addition, I am a cosponsor of the Dam Safety Act of 2006 (H.R. 4981). This bill reauthorizes the National Dam Safety Program Act, a law enacted in 2002 but which is due to expire this year. H.R. 4981 gives a new lease on life to a small but important Federal agency, the National Dam Safety Program. It provides much needed assistance to state dam safety programs in the form of grants, training, research and dissemination of technical information.

Also, I am asking for increased funds for the National Dam Safety Program. The Bush Administration has proposed $5.9 million for the agency for fiscal year 2007. I have asked the House Appropriations Subcommittee on Homeland Security to increase the funding level to $8.6 million, the full amount already authorized in law. These actions are fully justified by the huge scope of the need. According to the Association of State Dam Safety Officials, state governments oversee 92,231 dams nationwide (134 in Hawaii).

More than 10,000 are rated as “High Hazard” (77 in Hawaii). Ka Loko showed us what can happen when just one of those dams fails. The American Society of Civil Engineers stated in its 2005 Report Card for America’s Infrastructure: “Like all man-made structures, dams deteriorate. Deferred maintenance accelerates deterioration and causes dams to be more susceptible to failure. As with other critical infrastructure, a significant investment is essential to maintain the benefits and assure the safety that society demands.”

“Out of sight, out of mind” is a recipe for disaster. The tragedy on Kaua’i underlines the terrifying consequences of ignoring dam safety. Dam failures make the national news, but the root problem is the unseen deterioration that occurs over decades without being repaired. We must do everything we can to prevent the kind of catastrophe that occurred at Ka Loko. You can count on my continuing efforts keep the attention of Congress focused on this important issue. Sincerely, Neil Abercrombie, Member of Congress.

Congressman Neil Abercrombie
US House of Representatives: Hawaii, 1st District
Niel Abercrombie
Honolulu Office
Prince Kuhio Federal Building
300 Ala Moana Blvd.
Room 4-104
Honolulu, HI 96850
phone: (808) 541-2570 fax: (808) 533-0133

Washington Office
1502 Longworth House Office Building
Washington, D.C. 20515
phone: (202) 225-2726 fax: (202) 225-4580




Could this catastrophe have been prevented?

18 March 2006 - 4:00pm

the Kaloko Reservoir in better days. The Wailapa Stream, the flood course, is to the upper left

State got dam complaint 3 weeks before it burst
by Karen Blakeman on 18 March for the Honolulu Advertiser

A complaint was made to government officials about the Kaloko dam three weeks before it burst.

State officials received a complaint about flood waters from Kaloko Reservoir and at least one official was investigating fears of a dam breach before the dam came down Tuesday, according to the Sierra Club's Hawai'i chapter.

State Attorney General Mark Bennett said yesterday he was aware of an exchange of e-mails between state officials and the Sierra Club and was including it in his investigation of the failure of the dam.

"What happened several weeks before the catastrophic failure is something we will be looking into," he said.

He declined to comment further.

In a telephone message on the Sierra Club's Bluewater Hotline late on Feb. 21, a Kaua'i resident said she was concerned there was a breach at Kaloko dam above her property because a 50-foot wall of muddy water had careened past her house, destroying a bridge, said Melody Heidel, Sierra Club's conservation organizer.
The environmental group notified the state's departments of Health and Land and Natural Resources on Feb. 22.

"We received a message yesterday from a Kaua'i resident that the Kaloko Reservoir had been breached," Heidel wrote in an e-mail addressed to DLNR's "info" address and to Gary Ueunten at the state Department of Health's Clean Water office on Kaua'i. "The resident is concerned that their home is in trouble," she wrote.

Heidel said she never received a response from DLNR, which is responsible for overseeing dams.

Ueunten remained in communication with her.

"I have received reports that the reservoir dam has not breached," he wrote on Feb. 23. "I will forward more information as it becomes available." Ueunten wrote again.

"I was at the Kaloko Reservoir on Tuesday and the dam is intact," he wrote on March 10. Heidel wrote back, asking whether the rain, expected to continue over the weekend, would have an effect on the reservoir, and Ueunten responded on March 11.
"The Kaloko Reservoir is well below the top of the dam and the water levels are managed," he wrote. He wrote that perhaps the flood had been caused by debris that had dammed a stream.

Dennis Lau, chief of the Health Department's Clean Water Branch, said yesterday he was aware that Ueunten had looked into a complaint.

"I know he checked with the people up there at Pflueger who were monitoring it," Lau said. "And they said everything was OK."

Ueunten said yesterday he had been asked not to comment.

Lau said Ueunten's area of expertise was water quality, and he was not qualified to determine dams' structural stability.

"Our guy is not an inspector for dam safety. His job is to investigate water pollution complaints," Lau said.

DLNR did not respond yesterday to requests for information about the Sierra Club complaint.




In the wake of Ka Loko Reservoir

16 March 2006 - 8:45pm

aerial photo of damaged Morita Reservoir near the Kuhio Highway. Photo by Mary Daubert

Sierra Club's Blue Water Campaign extends sympathy to Kaua`i
by Jeffrey Mikulina on 15 March 2006

HONOLULU - The Sierra Club's Blue Water Campaign, like countless others across the state and nation, expressed their dismay and sadness at the damage caused by the breaching of Ka Loko Reservoir the morning of March 14, 2006. While the dam failure and subsequent flooding seemed to have caught most people by surprise, questions about Ka Loko dam were raised by the community and the Sierra Club as recently as three weeks ago.

On February 21, the Blue Water Campaign's Hotline (808-537-9019) received a complaint from a Kaua`i resident that a "50 foot wide flood" came down past her home in the Kamoku Hill area between Kilauea and Anahola, from the direction of Ka Loko Reservoir. The caller specified that the flood took out an unspecified bridge and the resultant mud flow had endangered their house.

The Blue Water Campaign forwarded this information to the Department of Health (DOH) and Department of Land and Natural Resources (DLNR) on February 22, and was notified the following day that DOH had received reports indicating the dam had not been breached.

"The Department of Health notified us that the dam was intact on a March 7 inspection of Ka Loko Reservoir, and indicated on Friday, March 11 that the water level was managed and not at full capacity," stated Melody Heidel, Conservation Organizer for the Sierra Club, Hawai`i Chapter. "Health Department officials also speculated that the initial flooding experienced in February may have been due to the release of debris clogging the stream, creating a flash flood, and that the County and State were still working to repair the affected bridge."

Government agencies have long been aware of the declining state of our dams, but the DLNR (which is tasked with monitoring dams in Hawai`i) has been chronically understaffed and under funded, increasing the possibility of a dam failure from threat to reality.

"This tragedy is a devastating reminder that we need to assess the current usage and effects of water manipulation and diversions across the state," said Jeff Mikulina, Director of the Sierra Club, Hawai`i Chapter. "Many of these 'natural' disasters we create ourselves through modification of natural resources, such as destroying wetlands around New Orleans, channeling or damming streams, grading and removing natural vegetation and trees that absorb water. We need to reevaluate the current need for certain reservoirs, particularly those initially constructed for irrigation purposes but no longer used for agriculture."

The Sierra Club is also concerned that what happened on Kauai was a result of urbanizing agricultural lands. According to Kilauea residents, when Kilauea Sugar was in operation, they maintained the reservoirs, such as Ka Loko. Even during extreme rain events a disaster like yesterday's never occurred. Once Kilauea Sugar closed, many of these reservoirs were transferred to private interests - some of whom have not maintained the spillways. Instead, the reservoirs have been reclassified as "lakes" and the areas around them marketed as lakefront property.

Jeffrey Mikulina: Director, Sierra Club, Hawai'i Chapter
phone: 808.538.6616

A Night to Remember
by Juan Wilson on 16 March 2006

path of destruction towards the Morita Reservoir from the Ka Loko Reservoir. Photo by Mary Daubert

A friend of ours has a home on Waiakalua Road. her property backs onto Wailapa Stream, where 300 million gallons of water passed from the Ka Loko Reservoir devastating homes and families below.

Her place is on a tight bend of the stream below the reservoir. As it rounds her property it is a gorge, perhaps 50 feet deep. She was awakened on March 14th by the sound of 75 foot tall trees snapping as the wall of mud and rock scoured the valley down to bedrock.

She went out in the dark to see what the thunderous roar was and neared her garden a bit below the upper plateau of her land. Even with a flashlight it was not clear what she was seeing in the beam of her flashlight. Below her feet was a raging torrent but it appeared to ramp up and away from her.

To her amazement and horror the turbulent surface of water was climbing the opposite wall of the valley as it banked and tilted around the bend in the stream. It was actually over her head on the far side of the stream.

for more images of disaster:

for a Flash File simulation of dam break:

for a WMV File simulation of dam break:


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