# How do you deal with clay??



## Summit Ridge Guy (Aug 16, 2010)

We have a short section of trail on Henrys Ridge that I call the clay mound or clay knob. It is an elevated section of trail with a 270 degree corner. The clay trail bed is rock hard in the dry season but in the rainy season it is as slippery as a greased pig or worse yet the top two or three inches of trail bed turn into clay mud.
- the trail really can not be re-routed.
- hauling gravel to the spot would be a real pain based on access

Any suggestions? Would putting a couple of inches of mineral soil on the trail bed help or would it all just turn to goo in the winter? This is the only section with clay that I am aware of in the area.:crazy:


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## indytrekracer (Feb 13, 2004)

*Clay*

Clay is generally pretty good if you can keep it from getting saturated with water.

In areas where clay was getting saturated with water, we have had success with building back channels to collect the water and taking it to armored low spots to cross the trail.

Seeps are typically the culprit.

Basically dig a channel into the back slop that is lower than the trail. Lower and armor the trail at one point to allow water that collects in the channel to cross the trail. For seeps, you need to try and find the source of the water.

Even a very small seep over time and soak a section of clay.


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## perttime (Aug 26, 2005)

I had reasonable success with a spot where the top soil is humus and there's water seeping over a 10 meter piece of trail. I did pretty much what indytrekracer suggests: dug a shallow ditch on the uphill side and routed it across the trail at the lowest spot. In this case, I found fist size rocks right below the surface when making the ditch and embedded them in the trail surface. Rain will still make it slimy but it does not become a muddy mess.


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## Summit Ridge Guy (Aug 16, 2010)

Thanks for the input. I had thought about a drain ditch on the inside "back slope". It is probably doable. There are some roots to deal with but that can be worked. I like the fist size rocks in the ditch, too.

The crazy thing about this is this section of trail is higher than the surrounding trail so you would think the water would just run off. But it doesn't.


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## Harold (Dec 23, 2003)

+1 on good drainage. I've dealt with clay in a few spots and getting the water off the trail quickly tends to resolve the issue pretty well.

drainage channels and armoring work.

Adding some coarse material can help some, but primarily in that it raises the trail bed above the moisture and enhances drainage.


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## perttime (Aug 26, 2005)

The drainage ditch probably doesn't have to be right next to the trail. The one I did is 1 to 3 meters off, where I found a good line for it between the vegetation.


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## Customization (Jul 12, 2011)

wood chips


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## HypNoTic (Jan 30, 2007)

Customization said:


> wood chips


Bad, bad idea. Unless you're dealing with a hiking trail.

For a mountain bike trail, wet wood chip are even more slippery than wet clay. Your solution is a mix of perfect drainage and rock armoring. Having a rock-armored foundation with 1in of clay on top might work pretty well. Also, decaying wood chips create the organic material we all like to hate : mushy black mud.

We also had good sucess with crowned thread in that kind of soil.


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## Summit Ridge Guy (Aug 16, 2010)

Thanks HypNoTic. I think some of my trail sustainability mentors would flog me if I used wood chips. So, what is "crowned thread"?


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## Fattirewilly (Dec 10, 2001)

Summit Ridge Guy said:


> So, what is "crowned thread"?


cut a hot dog length wise and place the flat side on your counter. If the hotdog was a stretch of trail, its tread would have a somewhat exaggerated crown. The issue with crowned tread or outsloped tread, it's usually defeated by use and compaction over time. That makes frequent grade reversals your long term best bet.

If your clay section is just one trail, could you just close it seasonally during freeze thaw periods?


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## Summit Ridge Guy (Aug 16, 2010)

Here are a couple of photos from both sides of the mound. This is the only section of clay we have. Some equipment had dug some drainage areas and this is the excavated dirt. So, I think the inside ditch with some fist size rocks is a good tactic. Maybe bringing placing some mineral soil on the tread and making sure everying drains inside will also help. 

Being is Washington we really don't have the freeze issue. It is just the rain!!


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## cmc4130 (Jan 30, 2008)

Summit Ridge Guy said:


> We have a short section of trail on Henrys Ridge that I call the clay mound or clay knob. It is an elevated section of trail with a 270 degree corner. The clay trail bed is rock hard in the dry season but in the rainy season it is as slippery as a greased pig or worse yet the top two or three inches of trail bed turn into clay mud.
> - the trail really can not be re-routed.
> - hauling gravel to the spot would be a real pain based on access
> 
> Any suggestions? Would putting a couple of inches of mineral soil on the trail bed help or would it all just turn to goo in the winter? This is the only section with clay that I am aware of in the area.:crazy:


what about pavers or wood-plank TTF's ?


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## perttime (Aug 26, 2005)

Ahh, so it is not on a hillside. Where does the water come from? Is it just the rain that soaks the clay? I don't see that the water could be flowing to that spot from anywhere else.

Looks like there is gravel and rocks right next to the trail. Or is the photo lying? Is it possible to remove much of the clay from trail tread, put gravel in its place and discard the clay where the gravel came from?


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## Summit Ridge Guy (Aug 16, 2010)

Figured photos would help. They were taken two months ago and it is dry now. There is really nothing on the the trail tread right now other than the clay. Logic would make you think the water would just run off since it elevated but the clay must act like a sponge. We have talked about pavers but again hauling anything back to this spot would take a crew of "bubbas". Prefer to try something with materials nearby or using tools.


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## Harold (Dec 23, 2003)

if the trail tread is absorbing lots of water in spite of the slope, it appears to me that the soil must contain more than just clay.

I've ridden many heavily clayey trails in the Great Lakes area (very dense clay resulting from glacial sediments) and the ones with any kind of slope tend to shed water well. they'll get a little greasey in the wet, but they hold together well.

I would suspect with all the green vegetation nearby that the soil has a significant organic component. Organics do tend to absorb a lot of water.

You could try a couple of things.
1. Dig a test pit nearby to see how deep you need to go to get to a more solid soil than is at the surface.
2. Amend the soil. You could choose something like gravel or sand which would improve the ability of the soil to absorb moisture quickly (rather than holding on to it) or you could choose something like a cheap clay kitty litter to make it hold together better.
3. Armor it. Bring in rocks and turn the area into a hardscape. Lots of labor.
4. Wood TTF. Less labor than rocks. Overall less durable, but with the right wood will still last years and get riders out of the goo.

Whatever you choose to do, do it in one area at a time and make sure it works for you before implementing it EVERYWHERE you have a similar problem.


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## Mr. Lynch (Jun 11, 2010)

Any cedar laying around the area? I can't remember if I've seen any out there or not. I know the spot your talking about and it is sloppy most the year. I think a split cedar bridge would be great if you have materials near by. 

that spot is a fun turn when dry, so I wouldn't dig it out unless you refill it with better soil. Just adding soil to the to won't help much though. I'd dig it down, add a ton of rocks that are abundant in the area and dig a burrow pit near by and cover it all in nice soil.


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## singlesprocket (Jun 9, 2004)

use a synthetic ground stabilization material as a base that has good transmissivity, build your trail on top. just choose the one best for your location...


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## Fattirewilly (Dec 10, 2001)

Summit Ridge Guy said:


> Here are a couple of photos from both sides of the mound.


I see a bunch of ferns in the photo. I don't know if they're everywhere in your woods or not, but around here they typically grow in areas that are more damp, have an underground seep, or similar issue which causes that area to be more wet. When designing a trail, I like to go around fern areas if I can because I realize the potential there for future problems. I find the solution is rock armoring the tread.

As suggested previously, you might also try digging in a ditch up above to try and divert some of the water flow coming into your problem area. That worked pretty good in one of my problem spots.


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## Ridnparadise (Dec 14, 2007)

I am thinking simple here. Clay makes awesome berm material. The steep slope of a well designed berm never becomes waterlogged.

The bermed entry to that corner looks OK. The wet spot looks like no berm makes sense, but think laterally - Berm the corner *into* the trees. Channel the water on the upslope side of the tread, where it is lowest. The clay base will make a good drain. Run it along the inside of the trail, maybe covered with rock, but I doubt there is room from your pics and then off the trail closer to the flat with a rock drain.

If you make a fairly subtle berm the outer border of the tread will not be frail and at an acute angle to the true slope across the trail. I hope I am making sense.


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## Ridnparadise (Dec 14, 2007)

Had to come back to this. The OP said a 270 degree corner and I forgot that. Bypass the corner. Just cut it out. How much trail could you lose, 30m?


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## J. Johnson (Feb 20, 2011)

Clay by it itself is unsuitable for tread. Wet it is a mess, but even dry it has little or no resistance to wear, and erodes fairly quickly, especially in the sun. But in some of the glacial tills that I have found most competent for trail building clay is an essential component, as it binds together the sand and pebbles to provide resistance to wear. So if you augment it (as suggested above) with the proper mix of other materials (not wood chips!) it can be pretty good. 

But you have to keep the water off, and proper ditching is a necessary. This can be a real challenge crossing a steep slope because there is a tendency to squeeze tread, ditch, and margins too tightly, and the ditching fails. If a slope is steep and wet -- and thickets of salmonberry or devils club are strong indicators -- you should look hard for another route.


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## Skookum (Jan 17, 2005)

i think the wood chips idea would be great if they were petrified wood chips.


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## Garry (Feb 17, 2005)

Clay trails are tough in the rainy season. We have clay trails designated that we close in the rainy season to minimize damage from bikes riding them when wet. In some sections we have added aggregate (stone, rip-rap) and soft sandy soil mix to harden it up. This helps hold the trail together, but still after heavy rains, even adding rolling grade dips for drainage, when the clay gets really wet it is a mess. Probably the best option is to cut an alternate trail around it for the rainy season. If left on it's own until dry there will be very minimum maintenance to it.


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## Ridnparadise (Dec 14, 2007)

Can you add finely ground coke to clay? I mean the other coke - coking coal: coal burned at high temperature like in the steel industry. It is basically carbon and bonds to stuff (like carbon pills bind gas in your guts). Iv'e never heard anyone try this, but could it work if stamped into the clay bit by bit over time like DJers stamp dirt on jumps???


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## Garry (Feb 17, 2005)

Don't know about the "coke." Never heard of that and it also seems labor intensive and difficult to get to the spot. It sounds like getting any material to this location is a lot of work unless you hook a trailer to a quad atv. If you can find lots of rocks (fist size and smaller) nearby have a crew with a lot of 5 gallon buckets move them there and lay a thick layer down when it is wet. Have people stomp it in too. Keep the bikes off of it until it has a chance to set and dry some. We've done that at Balm-Boyette here in Florida with much success. I don't know your area or accessability, but we have added service routes to get vehicles and ATV's into sections to work on them which makes it much easier to get material and people in to do repairs and builds. Still, a few of our clay trails are simply closed in the rainy season. There are alternate trails to enjoy while waiting for the others to dry.


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## J. Johnson (Feb 20, 2011)

If you only treat the _surface_ it quickly erodes away, and you're back where you started. To have a good surface you really have to think in depth, of the whole base and subgrade. If you are trying to augment clay you really need to deal with a large volume of material. As to what kind of material (coke might work) and what proportion, that is a deep question. I would suggest finding some competent glacial till (which tends to be a mix) and try to emulate it.

But not buckets! Unless you've got something small enough you are willing to do it all yourself, or want to test the steely resolve of your volunteers, use wheelbarrows! You can move more material, more efficiently, with less wear and tear on the crew.


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## Skookum (Jan 17, 2005)

J. Johnson said:


> If you only treat the _surface_ it quickly erodes away, and you're back where you started. To have a good surface you really have to think in depth, of the whole base and subgrade. If you are trying to augment clay you really need to deal with a large volume of material. As to what kind of material (coke might work) and what proportion, that is a deep question. I would suggest finding some competent glacial till (which tends to be a mix) and try to emulate it.
> 
> But not buckets! Unless you've got something small enough you are willing to do it all yourself, or want to test the steely resolve of your volunteers, use wheelbarrows! You can move more material, more efficiently, with less wear and tear on the crew.


:thumbsup:


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## Ks29er (Sep 13, 2011)

If you don't mind the extra effort, and you can get it to the site.....bagged sand works wonders tightening up clay...of course you will still want to have some sort of drainage in place.


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## Ridnparadise (Dec 14, 2007)

Don't forget to dance with the enemy - riding clay and modelling after as needed compacts it bit by bit. Test ride lots and lots. If there is a problem getting volunteers, get them to bring their bike and ride and ride and ride. Then adding a few bags of sand may make a massive difference where needed as the clay solidifies into Roman Ruins. 

We have found you can cultivate sand out of soil and fine silt out of clay by digging a pit where you would put a drain. Whatever drains into it when it rains will sediment out. You get little reservoirs of slurry for berms, or sand for drains etc. 

I realise this is not the point of the OP, but making hay....


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## J. Johnson (Feb 20, 2011)

But still relevant, and a good point, as pure clay will dissolve. You really don't want run-off taking away soil, but where it happens the silt that settles out in the hollows can be useful for filling dips. As it generally has had all of the clay content washed out it needs to have clay added to act as a binder. 

Though as I said, you really don't want run-off taking away soil. That is a matter not only of having good soil, but of adequate drainage and (most important!) avoiding excessive grades.


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