# Wood or dirt for your filler.



## Fletcher-Love (Nov 14, 2009)

Wood or dirt for fill on your trail features? I'm going to be building some larger free ride features for a new jump trail.. I've cruised the internet plenty looking at builds and I see a lot of wood framed jumps and dirt jumps framed by wood etc.... I always saw these as hand building techniques, because who realistically wants to build big jumps strictly outta dirt... by hand, especially when you consider that a small table with a 5 ft lip / 10ft long / 5ft wide is nearly 10 cubic yards of dirt!!! I build trail as my living with machines so wood rarely enters my mind when it comes to these types of features, but lately I've come to question that. Can I use wood as a filler? A jump is really just a takeoff and a landing right?. If your cleaning the jump who really cares whats in between. Has anybody used wood as a filler between their lips and tranny's? ( god that sounds terrible) Keep in mind I am not going to build gap jumps as this is a trail that is going to try and accommodate every skill level. I would also be filling over the top of the wood and on all sides with a lot of of dirt to keep the wood from being exposed to the elements. This is not a paying job, I would not be considering wood otherwise. Anybody done this? How long did it last?


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## Trail Ninja (Sep 25, 2008)

If you are using the wood as filler and not expecting to ride on it, leave it empty.

Wood will turn to mush and it will end up being like thin ice. It may look like you can walk on it but you'll fall through. You're better off with nothing than something that looks solid but isn't.

Burying it will make it rot faster than leaving it out to get wet and then dry out again.

If you are required to have the gaps filled (as I am in a lot of places) they will want them to *be* solid (rock & dirt) not just look solid ( logs topped with dirt).


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## Fletcher-Love (Nov 14, 2009)

Even with 3 or 4 feet of dirt on all sides of the logs? I have dug out old logs from the ground that have been relatively intact and solid and at least 50 years old. Keep in mind I've advocated against this practice in the past, but I'm wondering if it could work if the logs were encased within enough compacted earth.


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## Trail Ninja (Sep 25, 2008)

I guess it's going to depend on where you are and what wood you use. I've used log piles (hemlock & pine) well covered with dirt and I could only get about a year out of it before there was significant rot and loss of volume. Even leaving the bark on the logs exposed to the air was enough to accelerate rot significantly. We get about 70" of rain a year.

Lots of people do use log piles covered in dirt here but they're not expecting them to last. You can always add to it and pack it down every year.


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## Skookum (Jan 17, 2005)

Unless the trail is going to disappear in 5 years, i wouldn't do it. You're just going to make work for yourself or someone else.

Wood can be used when partially exposed because it can naturally breathe and dry out. It's still going to break down, yes even cedar which everybody thinks will last forever. 

If you have a good place nearby the site to harvest rock for fill you gotta think about that. Depending on how buff you want your trail you probably got a lot of rock around anyways.

Think about cutting and shaping down as well as building up. While you cut your drainage around the lip and landing you're going to get fill dirt there as well.

As far as wrapping your head around throwing hard work into your work, the positives should be evident. If you're going to do something for free, and it's going to have your stamp on it, you may as well do a quality job. In anything the more work up front the less on the back end, there really is no getting around that premise, and it's unfortunate that this type of thinking is losing ground. As i think it's connected to alot of higher problems in the world we now face...

But i digress...

Clear out a wider area, plan a bit more, dig down and build up, you'll still need to likely harvest rock/mineral from somewhere outside your super close work zone, but it's the way to go without cheezballin...


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## Skookum (Jan 17, 2005)

i may as well illustrate since i have pictures. 2 big rollers and a table for a dual line trail followed by a tiered berm. First picture look at the original level of the topsoil to the left. The natural grade of the original soil sloped downhill to the right. So you can see on the left side we dug DOWN, for quite a bit, and used harvested that soil for the 2 rollers.



This angle you can see the low end where the drainage is, we harvested alot of soil from there as well to add to the rollers and start the table, and used to build the berm



You see the lower tier of this dual track berm we cut DOWN. We used alot of that soil for the upper line to fill the backside of the upper berm, but we dug down deep enough to get a significant amount of dirt to finish the table.



i know i know this still is moving alot of dirt, but if you get the plan good you can still get alot of work done by utilizing the resources you have right in front of you. Because getting materials to the work site so many times is so time consuming, many times it's half the battle.


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## Fletcher-Love (Nov 14, 2009)

Sweet build man, top quality in the finishing department. I should clarify a bit as to where I'm coming from though. I get paid to build trail, very good trail. We are one of the best trail building companies in the nation. This year alone I've surfaced, paved sculpted and moved more dirt than most hand builders see in 5 or 10 years. As far as how to shape features outta the land, I specialize in this. This was a serious question that was coming from a machine building perspective. I never skimp on quality, its our trademark. I'm talking about building much larger features than your referring to in your pics, when you start moving 20 to 30 cubic yards of material for a jump the game changes. If I buried solid logs under lets say 4 feet or more of dirt on all sides encasing the log in an oxygen deprived environment how long would it last? Would the dirt around it pack in and hold its shape regardless of the deterioration of the log? The only application I was even considering this for was in between a lip and a transition. An area that realistically would be seeing very little tire use. There is also a very solid group of riders/builders maintaining these trails. Realistically I won't be doing this, but I do wonder why not and would like to hear from anybody that has tried it.


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## Trail Ninja (Sep 25, 2008)

Here:
http://bb.nsmb.com/showthread.php?t=56433&page=6

Universe has been using logs for fill for years. Ask him how long they will last. He's on Vancouver Island as I am, with really high rainfall.


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## Trail Ninja (Sep 25, 2008)

Something else I just thought of.

Wood buried in the ground is not only subject to normal decomposition but it's also accessible to all manner of wood eating bugs. I was thinking of a piece of deck that was touching the ground. In 5 years it was sawdust but the boards next to it, not touching the ground were still good and solid. That was definitely wood bugs and ants.


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## TunicaTrails (Jun 29, 2009)

We get these in rotting logs all over in Louisiana, which has the highest annual rainfall in the US of about 60 inches per year. I can actually tell you how long a lot of wood types will last on the ground in highly humid conditions since Hurricane Gustav knocked down a massive number of trees. Oak and cherry wood will succumb to rot and grubs after three years, gum in one year, pine about two years. Red cedar may stay around for as long as I need it. I plan to use a beautiful fallen red cedar tree for a bridge soon.


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## Landahl Calrissian (Nov 14, 2006)

The life expectancy of the wood all depends on the type of wood.
The page below has an accurate list of wood rot resistance and explains why.
http://web.utk.edu/~tfpc/publicat/decay.htm

Here in the midwest we have Hedge(Osage Orange -Maclura Pomifera) and have used it as fill and for other uses. Farmers use it for fence posts with good reason, a 6" post can last 40+ years in the ground.
Don't try nail into it though, it's hard as rock and hedge eats chainsaw chains twice as quick as Oak or other hardwoods.


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## Fletcher-Love (Nov 14, 2009)

I threw the question out and left it pretty vague to see what kinda responses it drew. I should be a little more clear with what I was thinking. I initially stated only using 1 or 2 feet of dirt over the top and sides of the logs, I should have said 3 to 4 feet of dirt. I'm thinking that this much dirt over the top of say cedar logs would last at least 50 years or longer if its encapsulated well and deep enough bugs can't get to it. I did some rough calculations and my whole idea is a mute point anyway, for the size of features I am wanting to build I would be needing 4 to 5 trees at least 60 feet tall and 8 inches wide to even make a dent in the amount of earth needed. My thought however was that if after clearing the trail corridor of all organics, I could pick the spot where i wanted my table top jump then I would dig a square hole 4 feet deep and maybe 4 feet wide and maybe 15 feet long. I would cut the cedar logs to an appropriate length and then arrange them in the hole, filling it almost to the top. Using the spoils of the hole i just dug I would fill over the top of the logs on all sides. I would have to generate more fill material than just the spoils of the original hole to cover the logs with enough dirt, but if the bundle of logs is fully encased in dirt and free of oxygen and bugs the deterioration has to be greatly reduced. Once again this is just an idea. I know builders fill over the top of wood all the time, i'm just talking about really burying it to delay the inevitable rot for as long as possible. A lot of old logging roads were built on top of logs and root balls. I know first hand about this after digging through old road beds. Even though I am not going to do this now, I am still curious as to what people think.


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## TunicaTrails (Jun 29, 2009)

Forgot about the best wood we've got down here, cypress. One of the world's largest living bald cypress trees is just a few miles down the road. There's plenty of fallen wood to work with in the swamps. Near this tree are several shells of dead trees also that have been allowed to stand for at least 100 years.


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## Skookum (Jan 17, 2005)

Fletcher-Love said:


> A lot of old logging roads were built on top of logs and root balls. I know first hand about this after digging through old road beds. Even though I am not going to do this now, I am still curious as to what people think.


i think old logging roads mean old growth timber, AND root balls that are saturated. The longevity is due to this fact. 
You just can't compare the quality of timber between the old growth and the stuff that's around today.

And thanks for the kind comments.


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## thad (Feb 25, 2004)

Andrew, wood fill is for lazy diggers. You will be using an excavator, no need to get lazy! 

I think you should identify areas that are suitable to dirt mining. I know keeping the surrounding woods undisturbed is high on your priorities. 

This is for the MoHawk project, I imagine. I would think a good way to build a line of tables, would be to dig down the run ins and run outs. If you excavated the these areas down 2-3 ft, I think you'd have plenty of dirt to build the tables 3-4ft higher, super wide and even. As long as you are doing this on full bench sidehill, I don't see any drainage problems.


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## Fletcher-Love (Nov 14, 2009)

Yes, Thad. Wood fill is for lazy diggers.... unless its buried deep, that takes a lot of work. The real deal here is I was just curious to see what kinda responses the question drew.


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## cmc4130 (Jan 30, 2008)

The consensus from other respected jump builders from other parts of the country is dirt only--no filler.

But here in Central Texas, it simply does not rain enough for log rot to be a threat to the integrity of the jump. There are jumps at 9th street (famous dirt jump spot) that have had logs under them for over 15 years, with no issues. In fact when dryness is your primary concern, I think a good base of large logs at the bottom of a jump helps maintain structural integrity. Clay dries out, crumbles and cracks pretty fast--within weeks or months. Heavy solid logs do not.

So, especially if you're just talking about the base of the middle of a table top, why the he11 not?

Also, keep in mind that the base of a table top must be a lot wider than the top surface because all dirt tends to pyramid out.... So, if the top of the table is going to be 4 feet wide, the table is really going to be more like 10 or 12 feet wide at the base.

Here's an old debate on ridemonkey about logs as fill: 
*"couple digging related technical questions for y'all trailbosses"*
https://www.ridemonkey.com/forums/showthread.php?t=202595

If you have this lying around, use 'em !!! But it's definitely a waste of time to go cutting down trees or hauling logs from another part of the park etc.


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## Berkley (May 21, 2007)

I've thought about using logs for jump filler for a long time. Our issue is that we don't have great dirt for packing jumps. We have decent dirt for packing, just not enough of it. Digging down and making pits is not an option because of rain. The photo in the ridemonkey link of the 4' deep pit could never work for us - it'd be a pond in no time at all. 

I see no problem using logs for filler (we've done it for rollers) as long as there's enough dirt on top. A lot of dirt, really - 6 inches at the least. If we end up building some real jumps, we will for sure use logs as a base. It's all we have to work with.


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## whoda*huck (Feb 12, 2005)

TunicaTrails said:


> We get these in rotting logs all over in Louisiana, which has the highest annual rainfall in the US of about 60 inches per year.


Uh, sorry. Not even close. Here in Makawao we get an average of 76.5 inches/year. Mt. Waialeale on Kauai is the wettest spot on earth with over 450 inches/year.


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## cmc4130 (Jan 30, 2008)

Berkley said:


> .... Digging down and making pits is not an option because of rain. The photo in the ridemonkey link of the 4' deep pit could never work for us - it'd be a pond in no time at all. .....


i solved this issue by simply digging a hole to the side of the pit that is deeper than the pit. it lets the water soak down. water will sit on packed clay forever (the riding line is packed), but it does soak into the non-packed hole faster. i have even see guys do 'french drain style holes in the side of the pit, where you dig a 3 foot deep hole then fill it with rocks.


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## Trail Ninja (Sep 25, 2008)

I was looking for something else for another thread and found this:

View attachment 595800


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## ivancormtb (Apr 14, 2020)

hello I was wondering how to make a landing solid so it can last forever the takeoff is wood also how should I build it so it looks good


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## Boulder Pilot (Jan 23, 2004)

ivancormtb said:


> hello I was wondering how to make a landing solid so it can last forever the takeoff is wood also how should I build it so it looks good


Concrete. The end.


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