20th Anniversary of the Archusa Dam Failure

摘要

Archusa Creek Water Park Lake Dam is a 32 ft. tall compacted earthen embankment dam with a maximum storage volume of approximately 9800 acre-ft. at the top the of dam. It was constructed in 1971 as a recreational water park for the public. The dam's relatively shallow depth, ranging from 4 to 8 ft., combined with the 87:1 drainage area to surface area ratio meant that the spillways operated constantly and had to pass nearly all of the in-flow coming into the lake. The dam had two spillways: the primary spillway, which had been modified in 1994 to an ogee crest with sluice gates and fish- retaining screens, and an earthen auxiliary (emergency) spillway constructed on very fine sandy soils. In January of 1998 the Archusa Dam drainage area received 6.5 inches of rainfall over a 3-day period, with 4.25 inches of that rain falling only a few hours prior to the dam failure. The dam failure occurred in the auxiliary spillway leaving a breach that was over 150 ft. wide and 26 ft. deep through the dam. The dam was repaired in 2003 with the installation of a 400 ft. labyrinth spillway that is still in operation today. This poster will focus on the history of the dam and subsequent reconstruction.