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Despite our best efforts to promote dam safety and assist owners in maintaining their dams in a safe manner, failures sometimes occur. The following paragraphs describe some recent dam failures in Washington and the lessons learned.
Seminary Hill Reservoir, Centralia WA
Seminary Hill Reservoir failed in October 1991 due to a massive landslide beneath the embankment. 3.5 million gallons were released in less than 3 minutes flooding a residential area.
The concrete overflow spillway had been modified to increase the storage of the reservoir, however this reduced the discharge capacity some 70 percent from the original design. The dam failed by overtopping during a flood in 1989.
Iowa Beef Processors Waste Lagoon
The Iowa Beef Processors Waste Lagoon failed when snowmelt in the area adjacent to the lagoon raised the water level to near the crest of the dam. Effluent flowed into animal holes near the crest and initiated an erosive breach. Over 270 acre feet of waste effluent were released downstream and washed out a railroad line causing a train to derail. The effluent was contained in another waste lagoon owned by a paper mill just upstream of the Columbia River narrowly averting an environmental disaster.
CSC Orchards, Frost Protection Pond
This failure occurred in July of 1995 due to erosive piping of the embankment materials along the outlet conduit. The reservoir was partially lined with a PVC liner, however, seepage passed beneath the liner and initiated the failure.
A 20 foot diameter sink hole appeared on the dam crest in December of 1996. A section of the drop inlet conduit running beneath the dam collapsed, resulting in embankment material being sluiced out through the break.
OVERTOPPING - 34% of all failures (nationally)
FOUNDATION DEFECTS - 30% of all failures
PIPING AND SEEPAGE - 20%
CONDUITS AND VALVES - 10%
OTHER - 6%
Project Name Location Date of No. of Nature of Failure and Damage
Failure Lives
Lost
Masonry Dam (Boxley Near North December 0 Excessive seepage through glacial
Burst) Bend 1918 moraine abutment caused mud flow
about 1 mi. from reservoir.
Destroyed RR line and village of
Eastwick.
Eastwick RR Fill Near North February 7 Blockage of culvert by slide
Failure Bend 1932 caused RR Fill to back up water
and fail. Destroyed RR line and
village of Eastwick.
Loup Loup Dam Near Malott April 1938 0 50 foot high hydraulic fill dam
failed when emergency spillway
was undercut during a flood.
Destroyed 25 homes and left 75
people homeless. Destroyed 1/2
mile of state highway.
Lake Dawn Dam Port Angeles February, 0 Heavy Rains caused overtopping
1950 and failure of earthen dam. 1
home destroyed, $4000 damage
North Star Sand & Everett December 0 40 foot high dam washed out by
Gravel Dams 1967 overtopping due to lack of
spillway. 25 foot high dam
rebuilt, also failed, washed out
GN railroad tracks, derailed
passing train.
Pillar Rock Dam Wahkiakum January 1970 0 Logging roadfill culvert blocked
County by debris, overtopped and failed,
caused 25 foot high concrete
gravity dam to fail. 3 homes and
fish cannery destroyed.
Sid White Dam Near Omak May 1971 0 Earthen dam failed due to seepage
through animal burrows. Caused
second dam to fail and dumped
debris into town of Riverside.
Horseshoe Lake Blowout Chewelah May 1974 0 Outlet tunnel through 50 foot
high natural ridge collapsed
causing ridge to fail. Drained
20 foot deep lake. Extensive
flood damage and debris deposits
on cropland in downstream valley.
White River Incident Near Auburn July 1976 2 Surge in flow caused by increased
discharge from Mud Mountain Dam
and removal of flashboards at
PP&L Diversion Dam. Killed 2
children playing in White River
Alexander Lake Dam Near December 0 Spillway undermined and failed
Bremerton 1982 during heavy rains. Caused damage
at fish hatchery and homes in
Gorst.
Upriver Dam Spokane May 1986 0 Hydropower facility failed by
overtopping. Lightning struck
system, turbines shut down.
Water rose behind dam while
trying to restart. Backup power
systems failed, could not raise
spillway gates in time. Caused
$11 million damage to facility.
Chinook Dam Pacific November 0 Heavy rains overtopped the
County 1990 embankment and undermined the
spillway, leading to failure of
dam. Approximately $100,000
damage to facility.
Seminary Hill Reservoir Centralia October 1991 0 Failure along weak rock zone in
City of Centralia hillside caused massive slide
which breached reservoir. 3
million gallons of water drained
from reservoir in 3 minutes. 2
homes destroyed, many homes
damaged, $3 million in damage.
Iowa Beef Processors Wallula near January 1993 0 Failure of 15-foot high
Waste Pond Dam No. 1 Richland embankment released 300 acre-feet
of waste water. Failure
attributed to high reservoir
levels due to snowmelt, entering
animal burrows near embankment
crest, and eroding dam. Washed
out Union Pacific RR tracks,
derailed 5 locomotives. $5
million in damage.
Copyright © Washington State Department of Ecology. See http://www.ecy.wa.gov/copyright.html.
