Presentation on theme: "Kelly Barnes Dam Failure"— Presentation transcript:
1 Kelly Barnes Dam Failure Toccoa, GeorgiaNovember 6, 1977
2 Kelly Barnes Dam Failure Failed about 1:30 am on November 6, 197739 people were killedDamages were estimated at $2.8 MillionPresident Jimmy Carter, at request of Georgia Governor George Busbee, authorized the Corps of Engineers make technical evaluation of dam and cause of failureAssessment team included U.S Army Corps of Engineers, USGS, U.S. Soil Conservation Service, National Weather ServiceFailure was to become the catalyst for the states establishing dam safety programs for private dams
3 The SiteDam and lake were located up a valley about 2000 feet upstream of Toccoa Falls in Toccoa, GeorgiaValley stream bed was about 40’ wideThe Falls were about 100 feet highImmediately below the Falls was the campus of Toccoa Falls Bible CollegeThe top of dam was at about elevation 1140 and the campus was about 850 – a difference of almost 300 feet
4 History of the Dam A rock crib dam was built about 1899 Used to power a small hydroelectric plant at base of the fallsIn 1937 Toccoa Falls Bible Institute built an earth dam over the crib dam for a more reliable power sourceAfter WWII, earth dam was again raisedOver time additional pipes/penstocks were installed in the dam and down the valley to the power plantServed as a power source until 1957After 1957 the lake continued to be used as a recreation sourceThe dam remained virtually unchanged until failure and no evidence was found of any inspection or maintenance program for the dam.
5 Dam Configuration Just Before Failure Dam was about 38 feet high – top elevation about 1140 mslDam was about 400 feet long , only about 200 feet of which was over 20 feet highCrest width varied but averaged about 20 feetNormal 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 controlThere was apparently no intake structure for normal pool controlDownstream slopes were steep ( 1v on 1 h in places) and had many large trees
6 Conditions Prior to Failure on November 6, 1977 Between October the area experienced about 3 ½ - 4 ½ inches of rainfallMore rain began on November 2 and by November 5 the area had received about 2 ½ inches of additional rainOn the evening of November 5-6, there were high winds in the area and one small tornado in the regionThe National Weather Service estimated that the total rainfall between November2 and November 6 was about 7”
7 Dam Failed at about 1:30 am on November 6, 1977 GA HWY 17 BridgeMobile home washed away
9 Impacts of Failure Dorm flooded to second floor Falls after the failure – note rubbleDorm flooded to second floor
10 Likely Cross SectionDam contained remnants of old construction – crib damPipes for penstocks embedded in dam – some dating to early 1900’sDam section was homogeneous – no filter zonesSlopes were irregularTree roots penetrated dam
13 Breach looking upstream Photos of FailureBreachBreach looking upstream
14 Views of Breach Left side of Breach Right Side of Breach- note remnants of rubble, crib dam, pipes, root penetration
15 Spillway in Left Abutment Photos (cont.)Spillway in Left AbutmentRide Home
16 Obvious Deficiencies in Dam That May Have Contributed to Failure Mature trees on dam with deep root penetrationBuried and deteriorating metal pipes in damSteep slopesLack of any inspection or maintenance
17 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 damOvertoppingCombinations of the above
18 Results of the FailureBefore 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 lawsThought 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.