Will a mud slide heal itself?

[fesser]

This is about as off topic as things can get, but I have learned that there are a lot of people on here with expertise in many fields, so...
I have a piece of land in the hills in Napa County Ca, that is mostly very steep hills and not of much value. But, I can go up there to shoot, cut down burnt trees, hunt, and generally relax. It burnt to a crisp in the fires a few years back and there are various issues caused by that. With all the rain we have been having, the dirt roads have been washing out, in part because small mudslides have diverted runoff onto the roads.
I got up there a couple of days ago and after getting past my problem areas I found a massive slide (by my standards anyway). It is basically about 50 yards long, and at the top it has slid down about two to four feet.

It is hard to describe, but directly below this area, maybe 40 yards, down a pretty steep hillside, is a switchback in the same road that was partially blocked by a slide. I am assuming it was the same slide, which would mean a big chunk of hill is moving. This is the lower switchback looking up the road that goes to the big slide.

We are currently in the middle of another big rainstorm which is likely to lead to more trouble on the hill.

So, I have what might be a dumb question, or one that can't be answered without more information, but...

When it finally stops raining, and if things look roughly like they do now, is the portion that slid downward likely to "reset" when it dries out or is it going to be compromised forever?

I feel silly for having to ask since I have been on or around similar properties for most of my life. I have seen D8's fill in voids that I could put three of my truck in, and we were driving on them the next day like it was nothing, but I haven't seen a whole shift of the hillside like this one before. I welcome any scientific wild *** guesses.

Thanks.

 

[Dako]

As far as ground settling on it's own, a builder told me they cannot build on an area that was filled in (without special compacting material) for at least 20yrs. Apparently it takes that long for natural earthen materials to settle.

As for hillsides, it's all stable...until it isn't. In 60+yrs I have seen areas where a road has been in place with no issues, long before I was born. Then, an event/ timeframe with above average rainfall occurs and suddenly an area gives way. Obviously vegetation loss can be a contributing factor, but it CAN happen anywhere...even without vegetation loss.

2 miles from home there were two small slides about 5 years ago. Both were covered over with batting to promote 'growth'. One is fine while the other has moved twice since then.

 

[Rick@Laysons]

Seeing the size and scope of the slide area, dirtwork with heavy machinery and maybe some terracing on the sidehills, along with top-seeding some kind of cover crop to help control erosion, might be the simplest way to go about it.

You might seriously consider getting with your county's soil conservation service. I'll bet they have some pretty good ideas how you might go about stabilizing the slide areas.

 

[Budnicks]

WE had a big slough off in the back 40, behind US, like 12 years ago
we cut into the hill, the uphill side some above it, a gradual slope
removed the loose stuff/topsoil (?), down to a harder surface/ground
of what we could see (widened the road/driveway there)
it's sort of a different color than the rest

to get back to what 'we assumed is virgin ground',
added a crapload of gravel/lime roadbase, like a foot thru that area
we have lots of clay & granite up here
it hasn't moved since,
it washed out the neighbor's road for a week or so, way back when

her road/driveway like 1/3+ mile long, is a disaster this season too,
with lots of erosion/ruts, exposed roots, gravel/roadbase dispersed
a small winter creek & a 1/2-2/3 acre pond has formed,
now that literally runs off her property now, everytime it rains again

but, no sloughing off thou, muddy as all hell
repair we did, it held

even with all this freaken' torrential rain/feet/s of snow, 40+ times
we had this year since Nov. 2022, like 100+ "s of rain
20' of accumulated snowfall, 3"-6" to 18"s to 2' at a time, melt & recover
it's like 268% of average

 

[cr8crshr]

Having lived in that part of the State for over 27 1/2 years...Vacaville and surrounding Solano Cty. area...and the countless slides taking place in winter time. not mush can you do to stop it and make it passable with out some very heavy equipment coming is as has been suggested. And is it even worth it??? I get the fact it's you get-away-place and pretty much isolated. Maybe investing a a Horse and do some riding up there would be a possible solution as at least what is now impassable a Horse can circumnavigate around it to get ya where ya need to go...Good Lick as even here in Reno NV area, we are getting just as soaked...cr8crshr/Bill

 

[Thrashingcows]

Well the fires coming through and killing off the larger stabilizing vegetation is the main contributing factory to your slides. Without those deeper root system interlocking and holding the soil in place in times of heavy saturation the hill sides are gonna move. Things will settle and new vegetation will grow but until new pioneer plant/shrub/tree species establish themselves the potential for slides is going to be significant.

 

[fesser]

Thank you all. Lots of good information to dwell on while waiting for the rain to stop. FWIW, I am not interested in getting the county up there for any reason. That is a door I don't want to open. They like to red tag, condemn, and mandate changes. Then they like to hang around and visit to ensure compliance. I mentioned that the property is pretty much all steep hills. They drain into waterways. The county is not going to want any muddy water ending up in the creeks at the bases of the hills. I would have to buy stock in waddles. I am crossing my fingers that this new storm system doesn't take the slide all the way to the bottom. I am done with horses, and it is too far to walk to the top.

 

[69a100]

FWIW, I am not interested in getting the county up there for any reason. That is a door I don't want to open. They like to red tag, condemn, and mandate changes. Then they like to hang around and visit to ensure compliance.

The county is not going to want any muddy water ending up in the creeks at the bases of the hills. I would have to buy stock in waddles.

So what's it going to be? You going to the county for help, or the county coming to you with penalties for mudding the waters?
You can't have your cake and eat it too!

 

[fesser]

So what's it going to be? You going to the county for help, or the county coming to you with penalties for mudding the waters?
You can't have your cake and eat it too!

Well, how about this, I am not going to invite the county in to inspect my cake.

 

[threewood]

Without any mitigation such as culverts and drainage it will not get better. Could cost a lot of money to fix. Can you cut in another road with heavy equipment?

 

[fesser]

Without any mitigation such as culverts and drainage it will not get better. Could cost a lot of money to fix. Can you cut in another road with heavy equipment?

In the areas where I took the photos, I think it can be done. Below it, where the switchback is, I am not so sure. It might be possible to follow the base of the hill around and come back with another switchback further up. Never really looked at it with a new road in mind.