The outer boundary of the city's compost/mulch processing facility. Very old mulch, piled high. Anyone can drive in and load bags with as much as they want. In my (sadly) bygone garden-crazy days, I would have been a regular visitor. There are different grades - coarse wood fiber for ground cover and fine for the compost piles.

There are probably some Canada goose nests on the top that we can't see. They are major contributors to the compost! ;-)