For a short while, I was boarding 3 horses and during this time of year was blessed to get at least one large wheelbarrow full of manure and bedding per day. Per day!
As I was breaking out new garden area, an area that desperately needed fertility and organic matter, I made long windrows of it to correspond to what was to become raised beds. Laid down one year, rotted during that year and planted the next. Last year it was hardneck garlic. Got my seed bulbs from a supply house and his recommendation was to work a lot of organic matter into my beds before planting. I told him what I had done and what I had and he became so giddy he was almost levitating with excitement.
Long story short, you have something of great value, so dig it out and use it!
It looks like the side is open enough a guy with a Bobcat could get in there and make short work of it. If nothing else, make a mountain of it near your garden and pull from it as needed or as you can. The same guy who has the bobcat may also have a small dump truck.