As the dam breach flood waters crashed down on four-year-old Bradley Gale Brown, early on Sunday morning June 16, 1963, he had no idea that there was a brand new, but defective dam only five miles upstream from his family. This dam had just failed catastrophically, on its first filling, sending eight million gallons per minute downstream. While his father frantically moved the station wagon full of some of his sleeping family, he could not imagine the magnitude of the flood that was sweeping the adjacent tent full of young boys down the river. Bradley’s older brother survived but had to go to the hospital after the incident. His two friends swallowed copious amounts of water and sand but were uninjured. Bradley was not so fortunate; he became the first dam failure casualty in Utah history. Bradley would be 45 today, if he had survived.
When
the Browns selected the campground on the Duchesne River in the Uinta
Mountains, fifty miles east of Salt Lake City, they had no concept that they
were camping at the headwaters of a tributary to the mighty Colorado
River. The Colorado had politically been
appropriated among its contiguous states, years before the Depression, with the
Colorado River Compact, and the participating states were finally taking their
fair share of the water. The young
family was unaware of the plan, devised years before the Second World War, to
divert some of Utah’s share of the Colorado from the river’s natural basin
towards the Provo River and Salt Lake City.
There was no Economic or Environmental Impact Assessment, no Hazard
Assessment or Risk Analysis, and no Standard Operating Procedures or initial
filling plan devised for the water project.
There was no Emergency Action Plan, Inundation Study or Evacuation Plan
prepared in case of an accident at the dam. It was the early 1960's, when John
Kennedy was President and the country still enjoyed a post war confidence and
prosperity. These were heady times when
seemingly infallible scientists and engineers ruled the country, putting a TV
in every home, a man in outer space, and a dam on every river.
The
Little Deer Creek dam was part of the Kamas Water Project, conceived in 1944
and eventually approved by the Utah State Water and Power Board in 1958. The dam was planned in conjunction with the
Duchesne Tunnel project that piped Colorado River water to the Provo
River. Little Deer Creek was a small
tributary to the upper Duchesne River.
These tributary waters could be collected, stored and diverted to flow
through the tunnel after spring runoff, with the construction of a 1500
acre-feet in stream reservoir behind a 75-foot-high dam perched at nine
thousand feet. The Duchesne Tunnel was
already functioning at its design capacity in 1958, diverting as much of the
peak snowmelt runoff as it could manage.
The Provo River was showing the effects of this additional water and
energy on the natural peak spring runoff flows which caused the adjacent
landowners to justifiably fear flooding, bank erosion and destabilization of
the river. Flows from the adjacent Weber River were also added to the Provo and
a protective dike system was consequently constructed to contain the additional
flows, which further exacerbated the destabilization of the river. Upstream storage on the Duchesne would allow
diversion of snowmelt water during the summer months when flows in both rivers
declined substantially and additional waters could help the wildlife and the
riparian environment. 
The
three pages of the dam’s design drawings, prepared in 1961, were based on only
three test pits and three drill holes.
The simple homogeneous design included a 3-foot-deep cutoff, an 18-inch
reinforced concrete culvert in a concrete cradle and a spillway over the left
abutment. Elvon Bay was the site
engineer for the State Water and Power Board and recorded the construction log. The Weyher Construction Company won the bid
and began work late, in August of 1961, after finally receiving design approval
from the State Engineer, Wayne Criddle.
Les Staples was the job superintendent for the Weyher Company. The earthwork subcontractor was the Berquist
Construction Company, represented by John Mills.
The autumn of that year was especially inclement and the contractors worked in difficult, wet and cold, early winter conditions. The construction log made many references to the freezing weather, the wet fill, the jointed and fractured condition of the rock on the right abutment, the probability that it could seep and pipe, the inadequate cutoff (bedrock was 17 feet deep) and the lack of structural integrity of the outlet pipe. The US Soil Conservation Service, in their review of the dam, made several comments about the design and recommended a drainage system on the seep area on the south (right) abutment. During the first construction season, water was noted flowing from the right abutment downstream of the dam but it was determined that it was “not to be coming from the dam.” This water, however, was noted to be flowing with a muddy color, the color of the fill material of the dam. Instances were noted of the placement of wet, sloppy fill during rain and snow events with moisture as high as 16.8%. Instructions were given to leave rocks in the wet fill, not to over compact, to place fill in 1-foot layers and compact to 95% density. This was later reduced to 92% density and 9% moisture, not the design tested optimum of 6%. Work was stopped on October 26, 1961, because of bad weather and wet-fill conditions. The outlet gate was not installed and the reservoir did not fill that first year. Heavy snows closed all the roads a few days later; some of the work crews barely got off the site before winter set in.
In July 1962 work began anew after melt-off
and the downstream dam face, or “backside”, was described as “spongy” with a
small slump formed in wet material, emanating either from a seep or a
snowdrift. A serious shear zone was
defined, removed and recompacted.
Although the dam appeared in “rough” condition, the dam builders
confidently said they could repair the slump, re-compact, and make the dam
structurally safe. A spillway was dug
from the natural ground on the left abutment and coated with rough concrete on
the right (dam) side of the channel, before it passed the downstream toe of the
dam and dropped steeply down the slope to the main channel. A large section of the reservoir basin and
right abutment were cleared of trees.
There was a small stream/spring noted entering the reservoir just
upstream of the dam. A diversion was
made from lower Little Deer Creek to the entrance of the Duchesne tunnel. The
outlet gate was installed and closed.
The dam was completed that autumn at a cost approximately $100,000.
The dam failed
during its first filling in the Spring of 1963 with the water at elevation 9215
feet, or sixty-two feet on the concrete stage gage, with 1200-acre feet in the
reservoir, inundating over twenty-nine acres.
The spillway elevation was 9223 feet, with the top of the dam at 9228
feet. Breach times were recently
estimated at between 1.0 - 1.5 hours, with maximum flows estimated at between
14000 and 17000 c.f.s. The final breach was eighty feet deep and seventy-five
feet wide and extended below the dam to bedrock. Downstream damage was extensive and is still
visible today. There was a scouring of
the immediate downstream toe area, followed by several acres of deposition
above a grade control rock out-crop where pieces of the outlet remain. Below the grade break is another steep,
scoured channel that dumps into the much flatter Duchesne River, downstream of
the diversion dam for the Duchesne Tunnel.
There is a huge debris deposit at the confluence that backs up a small
lake/wetland area to the base of the diversion dam. After the dam failed the flood waters took 5
hours to reach the towns of Hanna and Tabiona, fifteen miles away, and roughly
12 hours to reach the town of Duchesne, forty-five miles away. It was reported that ten out of eleven bridge
crossings on the Duchesne River were washed away with the flood and there was
also minor damage to farms next to the river.
It also inundated the small Ashley National Forest campground on the
Duchesne River. The bridge repairs were
estimated at $190,000; the Browns filed a claim for $31,000; additional claims
totaled $96,000. No civil suits or
criminal charges were ever filed, and no licenses were reviewed or revoked on
account of this failure. There have been
several other catastrophic dam failures in the state of Utah, with two other
related fatalities, but this failure was perhaps the most costly.
Today,
the remnant of the Little Deer Creek Lake has a small, natural grade control at
the outlet and supports a healthy lake, wetland and littoral area. Moose were feeding in the lake as I performed
the forensic reconnaissance in August 2002.
The clearing originally done for the lake was evidenced only by the age
of the younger trees growing below the old high-water line. The stream flowing from the right abutment
near the outlet intake was flowing one c.f.s. and an adjacent spring was
flowing 5 - 10 g.p.m. during the latest visit.
A complete section of the dam embankment, with a vertical face, remains
on the right abutment but the left side of the dam has been completely removed.
The most striking features of the small piece of the old embankment are the
sandy gravel matrix with very little 200 minus, excessive amounts of 3 - 6-inch
cobbles and boulders as big as 3 - 10 feet in diameter. There is a slump on the right side of the
remaining crest over the right abutment.
The maroon quartzite, visible on the right abutment, is highly fractured
and jointed with intermediate green siltstone layers every 8 - 12 inches. The main open joint patterns trend steeply
downstream at approximately the slope of the stream and appear to be at a
favorable piping orientation. A piece of
the old spillway structure remains high and dry on the left abutment, with a
“Utah State Engineer” survey monument embedded in the concrete. A 72-foot section of the storage gage remains
on the upstream left abutment; the borrow pit of the right abutment still
contains an old culvert and plow blades.
The
Fuhriman and Rollins Engineering Company prepared a report on the failure in
November of 1963. This report cited
seepage, through the unsealed and unfiltered right abutment, as the probable
cause of failure. Attorney’s briefs
concerning the case also noted the wet weather, wet fill, insufficient cutoff,
large boulders in the fill, insufficient bedrock preparation and a change in
the specification from a zoned embankment to a homogeneous embankment. Optimum
densities of the embankment soils tested after the failure were 137.8 lbs/cu ft
and 6% moisture; more dense, dry and closer to optimum than those tested during
construction. From the lateness of the
dam design submittal and approval that delayed construction until August, to
the bad weather encountered during construction, a series of mistakes,
oversights and natural conditions contributed to the failure. The design and exploratory testing were
marginal, the site preparation was minimal, the construction quality was
questionable and the condition of the bedrock was underestimated. The dam was built seventeen feet above
bedrock with only a 3-foot cutoff and the right abutment was not blanketed,
drained or filtered. Large boulders and
wet soil further compounded the probability that something catastrophic could
happen. Seeps and slumps after the first
winter gave clues that something was not right, yet only Band-Aid solutions to
these problems were implemented.
One
mistake is usually not enough to cause a catastrophic failure of a modern
earthen dam, given the redundancies of the design as well as the large factor
of safety attributed to the materials and dam geometry. Earthen dams are usually very flexible and
forgiving, provided that they are built properly out of the correct material
and that seepage is properly collected, controlled, filtered and conveyed away
from the dam. Most likely, it was a
combination of several small deficiencies that caused the ultimate
failure. Perhaps it was overzealous
water resource development, bureaucratic delay, unfortunate weather,
inexperienced personnel, budget constraints, unfavorable site conditions, ego,
arrogance or our consistent underestimation of the patience, power and
recklessness of water.
The problem
with dam breach forensics is that most of the evidence is flushed
downstream. Hindsight is 20-20 but
sometimes we don’t know what we don’t know.
The remains of Little Deer Creek Dam still stand as a monument to the
delicate humanity of Bradley Gale Brown, to the humility of the men who built
it, and as a warning to future generations to respect the strength and
complexity of nature. Hopefully, we
learn from our mistakes, ideally before we repeat them.
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