Trail Seasoning and Drainage for PNW conditions

Thanks. The advice I have gotten so far has been helpful. Even the stuff I thought I already knew feels closer to "now I feel like I know for sure." The conditions here are pretty similar to Western BC. There are plenty of zones with rock and cedar but the area I am building in is a research forest that has been cleared of cedar a long time ago and just happens to not have that much rock relative to other spots. Won't bother with the geology of why. Also, not so many experienced builders close by but Black Rock (have you heard of it?) is not so far. Could go to a build day there. And on and on… Thanks again.

if youre relatively close to black rock you might have some of the best dam gold around…that shit there is almost like rubber when its paked down n tacky -- little ball bearings get deadly though when it dries up. Only place ive ever rode where trail days include a leaf blower to blow off all the little ball bearing…

Get Diggers video "The Last Digg " - the tutorial at the end of it has some amazing tips on building for drainage … i'd be depressed building in a zone with no cedar.

maybe post some pics if you can, easier than trying to describe the soil

if youre relatively close to black rock you might have some of the best dam gold around…that shit there is almost like rubber when its paked down n tacky -- little ball bearings get deadly though when it dries up. Only place ive ever rode where trail days include a leaf blower to blow off all the little ball bearing…

Get Diggers video "The Last Digg " - the tutorial at the end of it has some amazing tips on building for drainage … i'd be depressed building in a zone with no cedar.

Thanks. Will see about getting the video. Checked out the trailer but did not find a place to get/buy the rest in a quick search.

Encouraging to hear about black rock. I am close to there (20 miles maybe) but not sure how similar the conditions are (of course, they can't be dramatically different but black rock is a little deeper into the coast range and I know how much more rock it has).

And,yes, it would be better to have cedar to build with. the fir at least behaves well when making boards and building.

maybe post some pics if you can, easier than trying to describe the soil

Will do. Thanks. Gonna do some building this afternoon. The soil packs well and holds together well when its not so wet that it is muddy. In the summer it is great and even when its not too wet in the winter (which isnt often). Once it gets drenched it is either hopeless or needs to be more compacted/seasoned then I have the means to manifest.

like i said, though, pictures to come.

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OK, so here is what I am working with on a lot of the trail. When dry it packs well and holds its shape. In the rain, even on very moderate grades with lots of drainage structures it can get VERY mucky. In my hand you will see how well it can bind itself. the dog tracks give some sense of how mucky the trail gets and what even a dog can do to it when it has gotten a little rain.

Did you roll a 'worm' with the soil? I bet you could make a kick ass one. From here it looks like you are dealing with a clay loam. It will harden over time, but winter is not the best time to build in areas with clay.

We have a few areas here that are heavy to clay, I try to work on them in late spring / early fall, when you have a bit of moisture but things don't get saturated. If you have riders on those trails at the same time as you are trying to do some earthwork (out sloping, grade reversals etc) you will be fighting an uphill battle.

That's very different soil you've got there. What happens if you dig down a foot or two?

This is the (not so) elusive "gold" people were referring to. If you can dig down and find it, you're golden.

These guys are in Oregon? What is WMBC? Is there a link to it?

WMBC is in Bellingham, 6-7 hours north of you. You should go to some Blackrock build days, especially since you are only 20 mins away. They have a build bay this saturday. The next is in a month. There are a bunch of cool people who know what they are doing digging down there.
http://brmba.org/events/

Watch the 60min IMBA "trail solutions" video on youtube. search google "surface water control" "USFS trail guidebook"

Looking at your pictures, the first thing I would try is getting all the organic off of the tread and away from the side of the tread where it acts like a dam, and leaches organic into the tread = muck.

I think you are going to need to cut the tread in more, and scalp all the brown/ organic off. Have you dug a hole anywhere? What do the soil layer look like?

You want the O and A horizons GONE. Pretty much anything green, brown or black.
KEEP DIGGIN'

The O horizon, as shown above, is the "organic" layer, a mixed bag of leaf litter and other organic bits found on the biome floor. This layer will vary with particular biomes, obviously, with deserts or tundra having very little litter at all.

In the topsoil layer, or A horizon, is usually associated with humus, mostly decayed organics that have been compacted and mixed with fine inorganic particulates such as clay, silt and sand.

The B and C horizons are mostly composed of inorganic rock in different sizes; C will have larger "chunks" than B.
This is gold. You want the trail tread gold and rocks, and nothing else.

Below C is the bedrock.

Did you roll a 'worm' with the soil? I bet you could make a kick ass one. From here it looks like you are dealing with a clay loam. It will harden over time, but winter is not the best time to build in areas with clay.

We have a few areas here that are heavy to clay, I try to work on them in late spring / early fall, when you have a bit of moisture but things don't get saturated. If you have riders on those trails at the same time as you are trying to do some earthwork (out sloping, grade reversals etc) you will be fighting an uphill battle.

Thanks. Makes good sense. And, yes, the soil can be rolled up into a worm pretty readily. I do not plan on opening it up for riding until it has dried out a bit (late spring or even mid summer?) However, can I hope to build a trail that will stand up to winter riding if I am using this stuff? Its ok if the answer is no and I have to look for other solutions (like ladders or rock, in spite of how difficult it is to get it here) just want to know what to plan for so I don't dig out a bunch of tread that will get blown out next winter.

That's very different soil you've got there. What happens if you dig down a foot or two?

This is the (not so) elusive "gold" people were referring to. If you can dig down and find it, you're golden.

Wow. Great pics. I don't think there is that "gold" layer here but I will check. Easy enough. I actually think the higher soil layer you have in the pics looks familiar. Like what it looks like here in the drier seasons. but ????

WMBC is in Bellingham, 6-7 hours north of you. You should go to some Blackrock build days, especially since you are only 20 mins away. They have a build bay this saturday. The next is in a month. There are a bunch of cool people who know what they are doing digging down there.
http://brmba.org/events/

Watch the 60min IMBA "trail solutions" video on youtube. search google "surface water control" "USFS trail guidebook"

Looking at your pictures, the first thing I would try is getting all the organic off of the tread and away from the side of the tread where it acts like a dam, and leaches organic into the tread = muck.

I think you are going to need to cut the tread in more, and scalp all the brown/ organic off. Have you dug a hole anywhere? What do the soil layer look like?

You want the O and A horizons GONE. Pretty much anything green, brown or black.
KEEP DIGGIN'

The O horizon, as shown above, is the "organic" layer, a mixed bag of leaf litter and other organic bits found on the biome floor. This layer will vary with particular biomes, obviously, with deserts or tundra having very little litter at all.

In the topsoil layer, or A horizon, is usually associated with humus, mostly decayed organics that have been compacted and mixed with fine inorganic particulates such as clay, silt and sand.

The B and C horizons are mostly composed of inorganic rock in different sizes; C will have larger "chunks" than B.
This is gold. You want the trail tread gold and rocks, and nothing else.

Below C is the bedrock.

Great info. Thanks for posting the cartoon diagram. I don't mind digging a bunch, but I am alone so excavating this whole trail to 10-12 inches is a, well, you know. Nonetheless, if that is the solution I will be happy at the very least to know what is and isn't working and why. So, thanks. I do right now dig down just as deep as it takes to remove the organic material/layer and to physically create a bench cut. Usually this is maybe 10-16 inches on the inside curve of a path cut into a moderate slope and maybe 6-8 inches for a trail being cut into a relatively 'shallow' slope angle.

As for rocks, I am learning that, in my area, building close to roads where I can poach rock from the ditches might be my best hope.

If you are hitting clay, there won't be any 'gold' underneath, just more clay.

This is the handbook I use for work. Check out page 271 for info on how to identify soils in the field.
http://www.for.gov.bc.ca/hfd/pubs/Docs/Lmh/Lmh28/lmh28-06.pdf

The key on page 272 will walk you through hand texturing soils.

Mountain bikers typically understand very little about soil science. For example 'we' call organics 'loam', and mineral soil 'gold'. When in fact 'gold' is actually a loamy soil.

I actually think the higher soil layer you have in the pics looks familiar. Like what it looks like here in the drier seasons. but ????

The upper layer in that pic is not soil, it's straight organics, rotting needles, wood, cones etc. Organics have no structural properties. You cannot roll it into a worm, etc.

See page 269 of the above link for more info on humus forms.

If you are hitting clay, there won't be any 'gold' underneath, just more clay.

This is the handbook I use for work. Check out page 271 for info on how to identify soils in the field.
http://www.for.gov.bc.ca/hfd/pubs/Docs/Lmh/Lmh28/lmh28-06.pdf

The key on page 272 will walk you through hand texturing soils.

Mountain bikers typically understand very little about soil science. For example 'we' call organics 'loam', and mineral soil 'gold'. When in fact 'gold' is actually a loamy soil.

My stab at the "gold" I have seen is sand/silt with a little clay which binds it - "sandy loam" in your reference document. Although I suppose you can defend calling it mineral soil - it is definately soil made of minerals. I like the descriptor "gold" as a trail building name - it works on an number of levels.

Cheers Ben