Download - Kelly Barnes Dam Failure
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Kelly Barnes Dam Failure
Toccoa, GeorgiaNovember 6, 1977
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Kelly Barnes Dam Failure
• Failed about 1:30 am on November 6, 1977• 39 people were killed• Damages were estimated at $2.8 Million• President Jimmy Carter, at request of Georgia Governor
George Busbee, authorized the Corps of Engineers make technical evaluation of dam and cause of failure
• Assessment team included U.S Army Corps of Engineers, USGS, U.S. Soil Conservation Service, National Weather Service
• Failure was to become the catalyst for the states establishing dam safety programs for private dams
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The Site• Dam and lake were located up a
valley about 2000 feet upstream of Toccoa Falls in Toccoa, Georgia
• Valley stream bed was about 40’ wide
• The Falls were about 100 feet high
• Immediately below the Falls was the campus of Toccoa Falls Bible College
• The top of dam was at about elevation 1140 and the campus was about 850 – a difference of almost 300 feet
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History of the Dam • A rock crib dam was built about 1899• Used to power a small hydroelectric plant at base of the falls• In 1937 Toccoa Falls Bible Institute built an earth dam over the crib
dam for a more reliable power source• After WWII, earth dam was again raised• Over time additional pipes/penstocks were installed in the dam
and down the valley to the power plant• Served as a power source until 1957• After 1957 the lake continued to be used as a recreation source• The dam remained virtually unchanged until failure and no
evidence was found of any inspection or maintenance program for the dam.
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Dam Configuration Just Before Failure
• Dam was about 38 feet high – top elevation about 1140 msl• Dam was about 400 feet long , only about 200 feet of which was
over 20 feet high• Crest width varied but averaged about 20 feet• Normal pool of about 42 acres ( 410 acre feet – 18 million cubic
feet of water)• Full pool was about 630 acre feet ( 27 million cubic feet of water)• An earth spillway beyond the left abutment and a “low spot” in the
reservoir rim on right of dam provided flood control• There was apparently no intake structure for normal pool control• Downstream slopes were steep ( 1v on 1 h in places) and had many
large trees
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Conditions Prior to Failure on November 6, 1977
• Between October 25-26 the area experienced about 3 ½ - 4 ½ inches of rainfall
• More rain began on November 2 and by November 5 the area had received about 2 ½ inches of additional rain
• On the evening of November 5-6, there were high winds in the area and one small tornado in the region
• The National Weather Service estimated that the total rainfall between November2 and November 6 was about 7”
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Dam Failed at about 1:30 am on November 6, 1977
GA HWY 17 Bridge Mobile home washed away
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Impacts of failure
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Impacts of Failure
Falls after the failure – note rubble Dorm flooded to second floor
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Likely Cross Section
• Dam contained remnants of old construction – crib dam
• Pipes for penstocks embedded in dam – some dating to early 1900’s
• Dam section was homogeneous – no filter zones
• Slopes were irregular• Tree roots penetrated dam
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Photos of Failure
Lakebed looking downstream Breach looking Upstream
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Plan of Failure
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Photos of Failure
Breach Breach looking upstream
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Views of Breach
Left side of Breach Right Side of Breach- note remnants of
rubble, crib dam, pipes, root penetration
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Photos (cont.)
Spillway in Left Abutment Ride Home
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Obvious Deficiencies in Dam That May Have Contributed to Failure
• Mature trees on dam with deep root penetration
• Buried and deteriorating metal pipes in dam• Steep slopes• Lack of any inspection or maintenance
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Possible Failure Scenarios
• Slide or slope failure leading to crest breach or “piping”
• Tree blowing over leading to “piping”• “Piping” along one of the abandoned metal
pipes in the dam• Overtopping• Combinations of the above
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Results of the Failure• Before failure, Corps personnel in Atlanta lobbied for a state dam
safety law for private dams – legislature did not support. • After failure – Federal government mandated states set up dam
safety laws or the federal government would do so. • Federal Government mandated an inventory of private dams and
provided assistance until states could develop capability and necessary legislation.
• During the late 1970’s and early 1980’s, nearly all states adopted dam safety laws
• Thought there was some minor regulation of dams in Virginia during the 70’s and 80’s , the Virginia Dam Safety Program was made into law in 1989.