SEISMIC MONITORING FOR BLAST DISTURBANCES TO THREATENED AND ENDANGERED SPECIES IN MISSOURI

In October, 2018, the US Army base at Ft. Leonard Missouri was going to conduct a biological assessment on the threatened and endangered species at the installation during the operation of a Mine Clearing Line Charge. As part of this assessment plan was a pilot monitoring plan was initiated to determine if such charges (blasts) surpass the thresholds of sound and vibration to various species including threaten bats. The pilot program will investigate seven caves within a two-mile radius of the blast site with King Cave being the closest (1.2 miles) to the blast site. At King Cave seismic and sound data will be recorded and at all seven caves acoustic (bat call) data will be collected. The seismic and sound data were recorded with an Instantel Blastmate seismic system where three components of the seismic signal is measured and a linear microphone was used to record the air blast from any detonations. Two recorders were placed at King Cave (one as a backup) two weeks before the scheduled blast. The seismic recorder was attached to the roof of the cave and the microphone was placed at the entrance of the cave. Data were recorded for two weeks and eight events were recorded. One air blast exceeded the Federal Limit of 133 dBL but was recorded on October 12. None of the seismic events exceeded Federal Levels. During the scheduled blast on October 22, there was no seismic activity recorded but the air blast was received and had a level 120.3 dBL which was below the Federal. Based on the seismic and sound activity during the Mine Clearing Line Charge, the seismic and sound levels were probably not large enough to disturb the bats at King Cave.