Sustainable Trails

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One of the most confusing and often frustrating issues surrounding mountain biking in our area is the concept of not riding on wet trails.

Put simply, to keep our trails from eroding we avoid riding wet trails. Many come from areas that don’t worry about wet trails or grew up riding their bikes in mud and wonder why they should care. The goal of this page is to help inform and educate. While this is on the Lebanon Hills site, it applies to many other trails in the metro area, state, and around the world. Please read on.

 

What Makes Us So Different?

There are many types of soils that make up trails such as rocky, sandy, loamy etc. The soil that makes up many of the trails in our area doesn’t hold up to use like other parts of the world. When wet or during freeze/thaw events our trail surfaces are susceptible to ruts and packing. We really are not the only area that struggles with erosion, however. Just search and you will find its not at all uncommon. Riders on a rocky Colorado trail can ride immediately after a rain without the same concerns over mud and ruts. So who cares about some mud or a few ruts? We all should, and here is why…

 

Land Management

When mountain bikers partner with land managers to begin a trail project, there are agreements made up front on how the trail will be built and maintained. Sustainable trails reduce impact to nature and reduce cost and time to maintain. If trails cannot be kept sustainable, they cannot exist. We would not have a trail like Lebanon Hills if the goal was to simply build a trail and then let riders destroy it. Trails in other metro areas are made possible by the success stories shared between land managers. If we don’t work together to keep our trails sustainable it costs us all by reducing future trail opportunities and can even result in closing existing trails.

 

Who are you to say when I can ride?

Training

MORC has a long partnership with the International Mountain Biking Association (IMBA). IMBA pioneered the concept of sustainable trails and is the go-to resource on this topic. To be a trail leader for a MORC trail, you must attend an IMBA led multi-day training course including hands-on training. Many of our MORC leaders have taken additional advanced level IMBA training as well. Only through this training and experience can one be put in charge of building and maintaining trails. These leaders are the ones that partner with the land manager on making decisions such as closing trails. All of these individuals also ride regularly and have a vested interest in keeping the trails open whenever possible. If you want an introduction to the individuals that lead the efforts at Lebanon Hills, check out the About Us section of this site. Before you do that, please read on..

Trail Science

Believe it not, but there are a lot of factors that go into sustainable trails. IMBA even has a few great books on the topic. In this next section we’ll talk about a few of the key concepts that damage trails as well as the science behind building trails that can best combat the negative impact. Hopefully it will be just enough to keep you interested:

 

Erosion

Erosion is the natural process through which rock and soil are worn away by wind, water, and traffic. Its also a trail’s worst enemy. Left unchecked, erosion can destroy trails and damage the environment. Trail erosion is accelerated by a combination of trail users, gravity, and water. All trail users loosen soil. Water compounds the problem if its allowed to channel of “focus” down the trail. Focused water can do more damage to a trail than any user (but is often caused by users). It gains velocity and energy, washing away precious soil and cutting deeper into the tread each time it flows. Trails like Lebanon Hills that are located in the heart of a metro area will get much more traffic than a typical trail might, which means the impact to the trails are magnified. Riding on wet trails contributes to a much higher erosion rate. You should now start to be able to imagine what would happen if the trails were left open when wet.

 

Freeze/Thaw

Most mountain bikers understand riding a trail when wet and muddy can cause rutting, puddling and other forms of trail degradation. However, many of these same users don’t understand that trails are at even greater risk during the freeze-thaw process.

During wet fall and early spring months, when the trail becomes saturated and temperatures drop, ice forms in soil voids. Through the night temperatures drop and the freezing process pushes soil grains apart reducing particle cohesion and soil strength and making the soil more erodible. During the day temperatures increase and the trail surface thaws.

Even though the surface has thawed, the ground is still frozen just below the surface.

To make matters worse, the frozen ground prevents precipitation from sinking in any further. This means the thawed layer at the surface is absolutely saturated with water so it is very intolerant of any disturbance. Come riding along and you’ll cut through the thawed layer right down to the frozen ground. The thawed layer will end up with ruts from the tire tracks, which will persist even when the soil dries out.

Certain trails in Minnesota typically see this around October-November, and again in March-April (as well as the months between if we don’t get a good snow cover). A number of factors play into how susceptible a trail is to the freeze-thaw process, including the amount of precipitation, the ability for the trail drain, soil type, and elevation. Due to these varying factors, one trail system may experience freeze-thaw when another trail system only ten miles away may be safe to use.

Please be patient and please stay off of the trails until the ground fully thaws. If you just have to ride then please plan accordingly so that you can complete your ride before the temperatures rise and the trail start thawing out.

 

Outslope

To try battle erosion, we design our trails with a certain formula in mind. A trail’s tread should always be slightly higher on the uphill side so that water can easily drain off. A gentle outslope of at least 2%, preferably 5%, is recommended. Trails without this outslope catch, hold, and channel water, helping erode and destroy the trail. Proper outslope encourages water to sheet across and off the trail.

 

But its just a trail in the woods…

Good Trail Design

The diagram to the right outlines most of the terms we use when talking about trail design. The berm on this diagram is what forms when trails are ridden wet. You can see how the berm (not the fun kind of berm that helps us corner faster) will disrupt water shedding across the trail. This water needs a place to go, so it now follows the trail. This starts a channel of erosion, which compounds the effects of the berm and starts to wash soil down the trail. These berms also hold water on the trail longer, meaning it takes that much more time to dry out and get riders back out on the trail.

 

I’m a taxpayer, I have rights!

 

Trapped

The diagram to the left shows how water will flow down a trail when its trapped. We create things called rolling grade dips to help push the water off the trail as quickly as possible. These rolling grade dips also provide that nice flowing feel to the trail. When we ride on wet trails, these grade dips quickly get blocked up by ruts and bermed trail. Moisture then starts to build up and either creates a muddy area, or eventually finds its way down the trail causing further erosion. If allowed to dry before riding, this would not happen.

When berms form, volunteers have to go out and fix these areas. These are the same volunteers that have built the trail and all the fun obstacles we all enjoy. When the crew has to focus on fixing, that means we don’t get new trails or obstacles. Imagine the work created by just one rider on a wet trail over 10-11 miles of trail. Often the crew gets so far behind in this work they have to rent a machine to do get the job done properly. This costs MORC money.

Example One

The photo on the right was taken at Lebanon Hills on the steep climb between #235 and #244. As you can see, erosion started to tear away at the middle of the trail, channeling any future rain and accelerating the damage. Originally we debated between re-routing or closing this entire section of trail. Instead, we built the new “Rockin’ Sally” Blue/Intermediate trail option to the right and re-labeled the climb a Black/Expert section. This reduced traffic enough to make maintenance of this trail manageable. This fix cost MORC $6000 and countless man hours of trail building and on-going maintenance. This is just one of many real-life examples of the costs of riding wet trails.

Example Two

Take over on the Galaxie side of Lebanon Hills, this photo is a great example of what happens when we ride wet trails. The trail starts to compact, channeling rain down the trail vs. off. You may not even notice it if the rain weren’t showing exactly what is happening. This results in trail damage that will be very costly to fix, especially on a trail that is over 10 miles long. By not getting the water off the trail quicker, the trail will also take even longer to dry out. Not all wet trail is mud like the more obvious photos, but might just be soaked and soft trail surface. This area of the trail is not known for rutting up, but still.. the damage is being done. Not many riders understand this. Hopefully you are now one that does!

Example Three

The photo on the right was taken at Lebanon Hills skills park. The lot and trails were closed, but some rider(s) decided they would ride anyway, leaving deep ruts in between the obstacles. These ruts ended up leaving a low spot which even today holds water and stays wet longer than it should. Because of this, the trails need to remain closed longer to dry out before we can re-open.. at least until we fix this area. A few minutes of fun potentially costing all riders valuable riding time.

The Science of Spring Thaw

Trails are dynamic and change with the seasons and weather conditions. While during most of the season the mineral soils that make up good hardened trails are fairly stable, spring is the most sensitive time for trails, making them vulnerable to erosion and long term damage.

As frost works its way through the upper soil cap, the soil moves and shifts. The trail loses density as frozen water pushes and prods the mineral particulate, and Mother Nature becomes vulnerable. As the frost thaws and releases water, the dirt resettles and realigns in a muddy mix, and the organic matter from last fall’s leaf litter blends in with the mineral soil to begin to create a new generation of trail dirt. This organic/mineral mix eventually re-hardens and makes for a primo path through the woods, but it’s critical to let this process happen on its own.

Dakota County Parks Patrol

This page would not be complete without mentioning the hard working members of the Dakota County Sheriff’s Office. Guys like Ryan and Chris take time out of their busy schedules to stop by the trails and watch for “poachers” (riders on closed or wet trails). Sometimes on foot, sometimes by car, and sometimes even on bike, they are out there enforcing the law and making sure that the efforts of the county and the volunteers is safeguarded. A ticket can run around $120, and they give out a few every year. Without someone showing riders there is a real consequence it would be very difficult to keep people off the trails. We couldn’t do it without their help, and so we’d like to take the opportunity to thank them once again for their efforts. MORC is fortunate enough to have partnerships with land managers and parks patrols in a number of our parks. I bet not many can say the same.

Lets Work Together

If you have made it to this point, we hope you have begun to realize that riding wet trails isn’t about the individual rider’s preference. Its not whether or not you care if your bike gets muddy… its not about whether you pay taxes… its not about the challenge… its not whether you CAN, its whether you SHOULD. There are thousands of mountain bikers to stay off closed or wet trails. We ask that you become a part of our community and help show others that mountain bikers are respectful of the land, those that make the trails possible, and their fellow riding community.

 

A Few More Facts…

Here is some additional facts and random information on this subject.

  • We ride too! Its not fun for us to have to wait on wet or closed trails either.
  • Traveling a great distance to ride a trail is never an excuse to be on wet or closed trails.
  • There are many places to check on trail conditions before you head to the trail. Twitter (all MORC trails), Lebanon Hills Facebook, and the MORC web site here (Lebanon Hills) and here (all trails). Dakota County also has a web page set up for conditions here or you can call them at 651-554-6530.
  • It generally between 12-48 hours for a trail to dry up. Sun, wind, rain amount, rain duration, humidity and previous rains can all factor in making it impossible to know for sure.
  • Land Managers open and close trails, usually in consultation with MORC trail leaders.
  • Only designated individuals should be out inspecting trail conditions.
  • You can get a ticket for riding, hiking, and even “checking out” closed trails. $120!
  • Do not ride wet trails, even if the gates are open.
  • Be aware of any weather in the area to save yourself a trip, or worse, getting stranded out in the rain.
  • It’s always good to check for local trail conditions before you ride anywhere. Respect the local trail volunteers efforts. Search for them on the Internet and thank them for the trails they provide.
  • See our Winter Riding page on best practices when we’re riding on snow.
  • See more photos showing the partnership between Dakota County and MORC in our Grand Opening gallery here.

Lets avoid building upon the stereotype that mountain bikers are selfish and follow the examples above. Doing so will allow us to continue riding all year long and keep riders on the trail as often as possible. There is a lot of effort that goes into making winter riding possible so please consider your fellow riders and the volunteers.