Mark,
I have played the Cascades course before and the Old Course near the hotel that Flynn redesigned after the Cascades project. It looks like he worked with what he had, but that is not so. Luckily I will be there next week working with John Hoover, the resort historian to better understand the genesis of the course. He has a keen eye for golf architecture and is making all the archival materials available to me. John has shared a few tidbits with me already and it will be a great story to tell.
There was quite a lot of engineering required. One of the first hurdles that Flynn (and perhaps Toomey) had to do dealt with the Swift Run stream that was subject to heavy flooding. This ran from the 6th fairway to below the 13th green. For more than half this distance the stream had to be diverted, bridged, or ran through culverts where it could not be moved. The way it was bridged was to lay locust logs on stone abutments covering a span of 40 feet then covering the logs with topsoil and growing grass on that. The worst difficulty was establishing the 12th and 13th fairways. They had to remove 300 yards of a limestone ridge and huge boulders, in remote and difficult terrain with the technology of the day.
We will detail more of the design and construction of the Cascades Course in our Flynn book. Given the very difficult task of constructing this course and the resulting natural look and feel, we have further evidence of Flynn's genius.