When is drainage too effective?

Just musing...

So it's been an unusually warm and dry April and some of the trails are nearing late-summer condition ie very dry and full of marbles. 

Are we now too efficient at shedding water off trails? What is the best option for the long-term health of a trail?

Separately, is there any downside to raking all the loose stones off a trail?

Posted by: SixZeroSixOne

Separately, is there any downside to raking all the loose stones off a trail?

I've wondered this too - it seems like the loose stones can result in trail widening in some cases where people ride around them. I think I'm doing a favour to do some, and realize it's dependent on situation, but am curious what the more experienced trail builders think.

The dry trails really have nothing to do with drainage, it's simply about the lack of precipitation. You can't manage water to keep a trail damp. The best option for the long term health of a trail is reduced erosion = less traffic, no skidding, no cutties and shedding water off the trail as opposed to letting it run down the trail. Raking all those stones into a pile can be good because they can be used to help fill low spots, anchoring posts for TTF's and a bunch of other things. A great thing to do is to build silt dams at the bottom of steeper sections as this way all the dirt that gets scrubbed off the top of the trail can get re-used to help fill low spots as the trail erodes. Another way to do this is through judicious use of grade reversals to help trap silt run-off. IMHO trail use has reached a critical mass where different techniques need to start being used and the trail system needs to be actively managed, including having more trails and periodic closure of trails. The hard part is getting the public to buy in. The other option is to simply let a trail go to shit until nobody rides it and then close it, rehab it, and open a new one. Just my 2¢ from my time wandering and working on trails.

better to have water drainage than no water drainage.  The 150mm days can seriously wreck a trail.  Dry trails will just need some maintenance and removing the pebbles/rock is fine.

Here’s what drainage does to the water table.  You've got me curious now to quickly go check out my Pangor reroute (which was bone dry in winter) before the next rains hit, but I don't think its marbles because its too dry.  

Marbles happen because the fine silt that holds then in place gets washed away. Stop the washing away, stop the the marbles...

Splinky, I would argue you can design a trail to stay damp but not be running waterflow. But you need to be able to build it from scratch with that intent in mind. Many of our trails started simply by riding downhill...

https://www.fs.fed.us/t-d/pubs/htmlpubs/htm07232806/page09.htm

The Fed has many online resources to learn about it

Maybe over a few days but you can't build a trail to stay damp in extended dry periods unless you build a retaining pond and put in irrigation. I don't think anyone is going to spend time or money to do that. 

Marbles also happen due to friction from tires displacing the fine dirt.

I have two retaining ponds Im testing out....

No way to get rid of marbles unless you sift the dirt and lay it down on top of hardpan which won't work when it's steep.  I haven't ridden Pangor for a bit but I remember it goes down a few creek beds.  Tough zone in there in regards to water management.   Trail probably needs a lot of realignment.

Posted by: LoamtoHome

No way to get rid of marbles unless you sift the dirt 

Sifting is un-rated. Time consuming but makes for a more durable surface. There is a drop on Pangor where the landing dirt was sifted way back in like 2011 on a Muddbunnies trail day that was very very durable. 

Thinking a bit about it now, heavy braking zones would benefit from using sifted gold in it's initial build, I think it would save future repair time further down the line.

Posted by: earleb

Posted by: LoamtoHome

No way to get rid of marbles unless you sift the dirt 

Sifting is un-rated. Time consuming but makes for a more durable surface. There is a drop on Pangor where the landing dirt was sifted way back in like 2011 on a Muddbunnies trail day that was very very durable. 

Thinking a bit about it now, heavy braking zones would benefit from using sifted gold in it's initial build, I think it would save future repair time further down the line.

In addition to getting the marbles out of the trail surface, the sifting likely helps with successful compaction as well. On gold trails, good compaction probably helps a lot with avoiding a loose surface.

A lot of the marbles probably also get deposited onto the trail surface by flowing water, so good drainage would help with that.

once the sifted gold gets compacted by tires, it basically turns into cement over time. I kind of like variable terrain but for jumps and berms its a good method if you got the time.

Posted by: earleb

Thinking a bit about it now, heavy braking zones would benefit from using sifted gold in it's initial build, I think it would save future repair time further down the line.

Grass pavers

There is a drop on Pangor where the landing dirt was sifted way back in like 2011 on a Muddbunnies trail day that still is very very durable.

It hasn't had a single shovel of dirt since and is pristine!