This small slash from depths between 12” and 24” was required to increase the ease at which equipment navigated the
corner in the drift. Three 1 1/2” holes were drilled to a depth of 4’ with a spacing of 18”. One 20 gram 34mm cartridge was
used for the 12” burden hole and two 120 gram 34mm cartridges for the 16” – 22” burden. The cartridge loading can be seen
in the center picture. The slash was completed successfully and material removed with on-site mucking equipment.
Connecting the Medical Center Metro Station with the Walter Reed National Military Medical Center, this 80’ long tunnel
135’ deep was stopped when conventional explosive sent vibration levels over tolerated limits. Nxburst with conventional
shocktube and surface delays was used by the Clark Construction Group to continue the work in a timely fashion all while
staying well below the vibration limits they could otherwise not meet.