How to fix mountain washout

[MACflyer]

I've got a trail that runs up the side of my mountain. It's badly eroded in one spot, I wanted to fill it in before it makes the trail impassable. It's washed out on the downslope side, and it's extremely steep. Not sure if I'd even be able to get up it on foot.

Initially I drove 4 metal t posts into the side of the mountain, parallel to the trail. I had some 6x6 fence posts from a fence I'd taken down, so I laid them down against the t posts. Then filled the whole thing in with dirt.

(The one t post at a wonky angle was too bent to drive in properly, but it's too steep to get down and pull it back out so I just left it. Not really doing anything to support the posts)

It looked great for about 4 days, when a heavy thunderstorm rolled through and the t posts failed.

My next attempt I'm thinking of increasing the amount of t posts, and then using rocks to fill in the bulk of the space with dirt added as a filler. The thinking is less diet to hold water means less weight for the bulwark to support. Does anyone have any better ideas or suggestions on how to build this before I go rappelling down the mountain to get the posts that washed out?

 

[Topzide]

Drive t post in further to hold better. Place them closer together for support. Rocks, cinder blocks and concrete chucks would all be good choices.

 

[John_Mc]

I'm trying to think of something more substantial than T posts to use as supports. They are not designed to support any significant side load, so there is a chance that even if you get them driven in far enough so the won't rip out, the posts could just buckle. I'm not coming up with anything off the top of my head that would go in without heavy equipment to install it. Maybe the galvanized pipe they use for posts on a chain link fence? (I've seen people use Black locust posts for their high rot resistance, but they had an excavator to dig the holes for them). On my own trails, we don't have anything so steep on the downhill side, so can get away with just burying logs parallel to the edge of the trail.

Whatever you end up with, one key to a long lasting trail is getting the water off the trail before it has a chance to build up velocity and damage the trail. When we are putting in trails on a side hill, we always outslope the trails a bit so that water sheds off of them, rather than running down along the trail, building up volume and velocity until it does damage. If the water is coming down in force from directly up the hill (rather than coming down the trail), you should focus on spreading and slowing that flow and/or diverting it to somewhere where it can't do that sort of damage.