What to do with an arroyo full of dead wood?

Permies, I need your advice and ideas for dealing with a big pit of wood. On some land I bought a few years ago, there is an arroyo/ravine where the former landowners threw woody material and some trash. They also threw metal, glass, aluminum, some building materials, two dog houses, one cigarette vending machine and a variety of other trash. The dimensions of the dead wood mass are 40 feet long, 15 feet across, and 7 feet deep in the middle of the stream course. I have pulled most of the trash from the wood as much as I can, but I am sure there is some hidden within. The wood is from pinyon and juniper trees, and has been there for 5-10 years without breaking down. My concern is that the arroyo is surrounded by live pinyon and juniper trees and this is a giant fire hazard waiting to torch my little forest.

My goals are to somehow break down the wood and make it less flammable - hopefully even making the area into a productive hugelkulture.

But - there are some contstraints
-The ravine slope is steep and I cannot maneuver an earth mover to dump dirt on the pit. I have tried several times. The only way to get to it is on foot.
-Biocharring with a barrel is time prohibitive as I could only process small amounts during limited times where a burn ban is not in effect.
-Woodchipping is also not feasible as I cannot get a chipper close enough to the area.
-The sides of the ravine are rocky and cannot be dug for dirt to throw on top.

Here's some pictures of... the thing

That's an interesting challenge. It's I guess dry enough that in these years it hasn't broken down, nor been swept away by floods (although I suppose that is always possible). I think before brainstorming I would want to know the chances that it might get swept away, before investing too much work in it.
It's a shame that it was so easy for them to dump crap and so hard for you to get it out. I suppose you could try dumping manure or urine on there, eventually maybe some sort of fungus (not sure how much fungus can work if it's that dry there)?

Great idea on the urine, I'll make frequent visits and that should start to compost it. As to your question, I don't think it will be washed away due to it's track record of existing. I also put in a significant amount of swales uphill of this area to control the erosion. That however will limit runoff from reaching the area and assisting with decomposition.

Hello Skylar. The surrounding landscape is sure beautiful!
Here are some observations and thoughts about the “big pit of wood” problem:
If your primary goal is to reduce fire danger, jump on that top twiggy stuff with heavy boots and use those board scraps to prevent falling into the depths of the hollow pile (less air in the pile means less fire danger). See if this brittle material will snap into tiny pieces. Bury the wood fragments with surrounding dirt to eliminate oxygen that would feed the fire.

However, if improving the fertility of the land is a goal, consider harvesting some the the rich material at the bottom of the pile. When looking at the photos of the debris up close (magnifying the posted photos), I can see that there is some fine mulch at the lowest places in the pile. The long twigs and larger branches on top may conceal a more broken down layer below the surface. Some settling appears to have happened over time. I would pull back the top layer and see what kind of gold is accumulating at the bottom of the pile. That might be some beautiful material for mulching trees in the immediate area or even some rich humus at the bottom of the pile if rainwater washes down and moistens the arroyo.

Posting this in the hugelkultur thread suggests you are considering making a fertile hill, either in the arroyo or someplace else. The rich soil is on bottom and the woody material usually buried is on top. For the hugel to break down the brittle top layer, a lot of effort will have to go into moving this whole wood pit or flipping this pile over! Maybe peeling back the top and seeing what is beneath will reveal some other options (like harvesting the humus and leaving the remaining crushed wood to break down into future humus).

So, the question is: do you want to harvest that black gold or leave it in the arroyo?