DALLAS MORNING NEWS-
By George Getschow | Special Contributor
Photos and video by Nathan Hunsinger | Staff Photographer
Published December 12, 2015
The problem — one of many — first appeared as last May’s record rainstorms quickly filled the region’s reservoirs. An instrument at the Lewisville Lake Dam showed pressure building under the downstream side.
Jason Vazquez, dam safety program manager for the Army Corps of Engineers at the time, collared another engineer, and in pelting rain they raced to the affected area, officially known to the Corps as “Seepage Area No. 1.”
Even during the seven-year drought, the area had looked like a swamp, covered with chest-high cattails and weeds. Corps technicians sometimes encountered water moccasins and alligators as they measured seepage. This time, Vazquez and his partner, wearing rain slickers and rubber boots, spotted something far more disturbing: water and sand bubbling up from a tiny hole in the ground.
Such a “sand boil” indicates that increasing seepage has created a passage under the base of the dam. If not stopped, it could lead to a rupture of the dam.
Vazquez remembers standing in the middle of the swamp, soaking wet, wondering whether the dam he nicknamed “Trouble” was about to become a regional disaster. The 35-year-old engineer called his bosses at the district’s Emergency Operations Center in Fort Worth. CONTINUE READING….
Sandbags and tarps have been deployed in an attempt to prevent further erosion of a 160-foot-long slide on the Lewisville Dam. To engineers, the slide’s proximity to another major one that happened in 1995 suggests instability that could threaten the dam’s foundation.
Only 34 miles upstream from Dallas, the 6.2-mile-long Lewisville Dam holds back 2.5 billion tons of water when the lake is full. That’s 125 times as much as the dam that failed in Johnstown, Pa., in 1889, killing 2,209 people in the nation’s worst flood.
