Vibrating the sheep pile to drive it in - I can hear this in my office on Clark (4 blocks down the river)
The guide is nailed down by the 2 smaller tubes (in back) which appear to be weleded in place. The 3 openings then have the larger tubes vibrated and pounded in.
Tubes that will be vibrated in, then pounded the last bit ?
the business end of the pounder.
not sure what the caps are for - would fit the big tubes
More pieces - cut up form - I guess they are custom built on each site.