The construction process required a three-story hole to be dug straight down into the earth, a 62 foot long steel reinforcement cage put in, and a cement tube to basically be built within. The missiles would be inserted and then a 110 ton steel and concrete plate would be put overtop of the assembly, armed with explosives to blow them off to make way for the launching missile. The sounds persisted every time maintenance workers entered the silo. Several men even reported the sounds of labored breathing and footsteps. It was mostly kept under wraps by base security. ...He was gripping a hammer.