On this date, 92 years ago the Great Flood of Louisiana implemented the existing levee system. Imperfect engineering and shoddy construction caused the collapse of dams, such as the Johnstown Flood of 1889.  On May 16, 1874, 138 people died as a result of poor construction and a dam break in Williamsburg, MA.  On March 12, 1928, the St. Francis Dam, in service less than two years, collapsed near Santa Paula, CA, killing 450. February 26, 1972, two coal slag dams along Buffalo Creek in southern West Virginia broke, unloading two miles of backed-up water into a lower dam that exploded, 4,000 homes were washed away with 125 deaths.  June 5, 1976, the 305-foot Teton Dam in Idaho collapsed, released 80 billion gallons of water into adjoining farmland. In closing, sound walls along Interstate systems are designed to eliminate noise in neighborhoods adjacent to the highway. This dynamic cold be compared to light hitting a prism, being slowed and breaking into wave lengths.  Sound is a wave that is muffled when it hits the wall. Similar to a wave hitting a dock, the sound wave will find a path. In my neighborhood the sound wall seems obsolete as the noise is louder than when you are adjacent to the wall.  If there is cold air at the surface, sound moves slowly. If there is warm air aloft, the wave moves faster and is dispersed beyond the sound wall.  Similar to shear, this occurs when the noises are elevated into the atmosphere and dispersed beyond the sound wall.