Ron - Yes, I wanted to see this video and watched it over the weekend. We had Hayward Baker do quite a bit of grouting at one of our coal-fired station sites in the early 1980's. I was surprised when Dr. Bruce mentioned the first use of a Hydromill in the U.S. (1983). This was on an unrelated Corps on Engineers project (St. Stephen Dam, image shown below) located on our hydroelectric reservoir:
SRE....yes, the video is good. It was popular in the 80's to fill subsurface voids in Central Florida by grouting. That has waned over the years because of expense and the unknown quantities required to fill some of our "never ending" voids!