No effort was made to preserve foundations or other wind farm infrastructure. CDI’s crew felled the 90 Units in two (2) mobilizations to the site, permitting the Wind Farm Owner to complete salvage of blades and drive-train elements from some of the wind turbines to provide replacement parts for similar Units they operate at other wind farm locations.
I can't find any info on when this wind-farm was constructed, but Democrtic Underground says that the first of the Mitsubishi 1000A Wind Turbines were installed in 2002, giving a maximum life of 18 years.
This is the video from Controlled Demolition, Inc. Felling of 90 Mitsubishi 1000A Wind Turbines.
And this video from Discovery UK still makes me smile. The Glaring Engineering Mistake That Made Wind Turbines Inefficient | Massive Engineering Mistakes
Believe it or not, when engineers first installed wind turbines, they thought they'd be pretty much maintenance free, but they were wrong.