Digging the foundations by hand - looks like Bob Speck appears to be waist deep.
RASC Hamilton Centre 1979_07_marsh
Scanned by Colin Haig 2006-03-18 to 2006-04-08
Scanned with Nikon Coolscan V ED.
These slides, from the construction of the Hamilton Centre Observatory, had a date on the slide mount, "1979 07 Marsh." I am not sure when actually taken or when developed. Abbreviations: JMH - written on the slide, likely the photographer. John Hudak is likely the photographer according to Roger Hill.