Duthie Hill Mountain Bike Skills Park is the second park built by Evergreen Mountain Bike Alliance. Located in Sammamish Washington, the progress within the first year has been amazing and not even in completed the park is soaring in popularity and receiving positive buzz.
http://evergreenmtb.org/wiki/index.php?title=Duthie_Hill
The Grand Opening of completion of Phase A is upcoming so there is a push to shore up all the trails. There are Freeride lines, practice lines, and nearly 5 miles of XC trails. As with all trails sometimes there needs to be more attention put into sections for a variety of reasons. And even the best built trail will surprise the trail builder with surprise issues that develop into problems. The goal for Duthie XC single directional trails is for them to be built sturdy and sustainable, so they can withstand high traffic, and events like races. The original goal of these trails were to shoot for buff, groomed, flowy trails, similar to what they enjoy in Bend Oregon, and unlike what is the norm for trails in our local area.
The trails are all completed, current usage already has revealed problems, so my task is to locate, identify, and "finish" them.
ACK! a puddle!!!! We'll start of with a simple one, picture below is a dip in the trail. Water settles, organics accumulate and the tire wear combined with the erosive powers of water will continue to make this puddle deeper as years go by.
i've drawn arrows to show where the water was intended to go, also note the little drip, a drainage had been dug out to the left. But obviously the trail tread is now lower than the drainage leaving a puddle. You can see i scooped out a couple buckets of really good mineral soil with lots of rock in it, perfect soil for this application.
And here's the final shot showing the fixed trail. Spreading and packing the dirt into a nice slope, so water will now have no problem finding it's way into the drain like originally intended.
Next up is an example of small stretch of trail that is caught in a neutral state. The arrow shows that water from one side drains where it's intended, but the dotted area shows a dead zone where it's practically level with the mouth of the drain, so water just sits there. When that happens organics build up, tires will eventually erode this section and cause ruts. If you also notice a bump that the McCleod is sitting on, i created that a few weeks before, but didn't finish the fix.
So since water runs down downhill we're looking at the + signs to help us envision a border, the + signs are the high spots.. Inside this area we use the yellow McLeod to scrape all the organics out, into the X pile, later we always throw this clutter off the trails broadcasting it out to feed the bushes. Our minus sign shows us where we need this water to go, the negative is our low point, our drainage. Already i've stacked some larger rocks to serve as a base for the soil build up we're about to put in.
Couple bucket loads of that really nice rocky mineral. Dump them out in a couple of lines to get a basic shape of what we need to do to make a slope for the water to shed off the trail. You see the McCleod is being used with the rake side to groom the shape, as well as take out rocks that are too big.
So here's the final shot we now have a nice slope so the water will now shed off the trail, and we'll have nice solid tread. Where before we just had film of standing water and gloop, now the arrows show the where the water runs toward the drip drainage, and we're good to go.
Ok this next fix is moving into more of an advanced area. But it's something that's real important to understand when doing trail work. You can first look at his picture and say, "i don't see anything wrong. There are no big puddles here!?" Well at first glance you would be right (even though the drainage did need to be cleaned of all those sticks and organic matter).
But the problem isn't the drainage here, the problem lies in the "flow" of this corner. You can tell by the frowny face this big high berm was intended to take the downhill rider to come out onto a sharper turn. But the blue dotted line shows that most riders don't take the berm as high as the builder thought, and they are winding up going left of the trail after the dip.
"Well so what?" you might say as this picture shows all the plus's and minus signs show the drainage is working good, water going toward the drip. Well the problem is the area i show in the dots. That section where riders are winding up is a section of trail that does not have a firm tread base. The edge of the trail there had alot of duff mixed in, so after a while there will be a rut. More riders will deepen the rut as they come down fast off the downhill corner, and brake and skid on it, and it will get worse and worse as years go by.
So the solution is to make a bump on this section. Berms are fun, but are not necessary for flow. This bump puts a nice inward slope to the trail (inslope). Generally you want to avoid inslopes because they prevent water from shedding off the trail, but in this case it's on the high side of the dip, so water drains fine. The dotted lines again show the common path of mt. bikers, only now the bump is there to help get the wheels back to the center of the trail with no trail damage done. This is an example of "flow", when speaking of the relationship of how a trail rides and responds to wheeled traffic.
A look from the other side. Dotted lines show path of bikes as they come around the downhill corner up from the drainage dip, and now onto this bump. The bucket shows the level of the inslope.
Ok let's examine how to make a bombproof bump. First after digging out duff to get down to the hardpack pack i piled up a nice pile of softball sized stones for a base. You can think of this like a skeleton.
Next we dump a pile of crushed gravel. The gravel will fill inbetween the rocks settling them in, as well as create the basic shape of the bump. You can think of this like a the cartiledge and tendons.
Ok this part is a bit overkill but i still was close enough to harvest this really nice rocky soil. So we can think of this step as adding extra muscle, we're giving this bump tread some steroids. Think of this as the muscle.
And a final "skin" layer of mineral soil, pack it down, and you have a solid tread that should last forever.
Ok the final problem we see has a combination of all these issues. After a downhill we have a dip drainage that is not draining well, and the arrow points to the log which is creating a visual obstacle which is pushing riders to the outside of the trail. The outer part of this bench was built over duff and organic and is breaking down on this climb.
So we show a puddle developing on the trail, the trail now rides over ferns, and above the edge of the trail breaking down. This trail isn't even a half year old, so this section needed attention right away.
Dig out all the crud. Throw in a bunch of heavy rock and bury that with a wheelbarrow full of crushed gravel to reinforce the tread.
And after a nice topping of mineral soil we have a tread that looks and rides way better.
Taking some steps back viewing the entire climb, you'll see i used a pick to re-work the drainage as well as used that and a shovel to dig out the duff base. Then we can reshape and reinforce the tread with a couple loads of crushed gravel. All the signs are showing we're getting all the water off the trail now.
As our final shot shows that right above of the dip i added some inslope to help get the wheels centered on the trail. With our final topping of mineral soil we have an example of sustainably built singletrack trail that drains well, flows (rides) well, and will not suffer from erosion.
Cheers, now go dig!
http://evergreenmtb.org/wiki/index.php?title=Duthie_Hill
The Grand Opening of completion of Phase A is upcoming so there is a push to shore up all the trails. There are Freeride lines, practice lines, and nearly 5 miles of XC trails. As with all trails sometimes there needs to be more attention put into sections for a variety of reasons. And even the best built trail will surprise the trail builder with surprise issues that develop into problems. The goal for Duthie XC single directional trails is for them to be built sturdy and sustainable, so they can withstand high traffic, and events like races. The original goal of these trails were to shoot for buff, groomed, flowy trails, similar to what they enjoy in Bend Oregon, and unlike what is the norm for trails in our local area.
The trails are all completed, current usage already has revealed problems, so my task is to locate, identify, and "finish" them.
ACK! a puddle!!!! We'll start of with a simple one, picture below is a dip in the trail. Water settles, organics accumulate and the tire wear combined with the erosive powers of water will continue to make this puddle deeper as years go by.
i've drawn arrows to show where the water was intended to go, also note the little drip, a drainage had been dug out to the left. But obviously the trail tread is now lower than the drainage leaving a puddle. You can see i scooped out a couple buckets of really good mineral soil with lots of rock in it, perfect soil for this application.
And here's the final shot showing the fixed trail. Spreading and packing the dirt into a nice slope, so water will now have no problem finding it's way into the drain like originally intended.
Next up is an example of small stretch of trail that is caught in a neutral state. The arrow shows that water from one side drains where it's intended, but the dotted area shows a dead zone where it's practically level with the mouth of the drain, so water just sits there. When that happens organics build up, tires will eventually erode this section and cause ruts. If you also notice a bump that the McCleod is sitting on, i created that a few weeks before, but didn't finish the fix.
So since water runs down downhill we're looking at the + signs to help us envision a border, the + signs are the high spots.. Inside this area we use the yellow McLeod to scrape all the organics out, into the X pile, later we always throw this clutter off the trails broadcasting it out to feed the bushes. Our minus sign shows us where we need this water to go, the negative is our low point, our drainage. Already i've stacked some larger rocks to serve as a base for the soil build up we're about to put in.
Couple bucket loads of that really nice rocky mineral. Dump them out in a couple of lines to get a basic shape of what we need to do to make a slope for the water to shed off the trail. You see the McCleod is being used with the rake side to groom the shape, as well as take out rocks that are too big.
So here's the final shot we now have a nice slope so the water will now shed off the trail, and we'll have nice solid tread. Where before we just had film of standing water and gloop, now the arrows show the where the water runs toward the drip drainage, and we're good to go.
Ok this next fix is moving into more of an advanced area. But it's something that's real important to understand when doing trail work. You can first look at his picture and say, "i don't see anything wrong. There are no big puddles here!?" Well at first glance you would be right (even though the drainage did need to be cleaned of all those sticks and organic matter).
But the problem isn't the drainage here, the problem lies in the "flow" of this corner. You can tell by the frowny face this big high berm was intended to take the downhill rider to come out onto a sharper turn. But the blue dotted line shows that most riders don't take the berm as high as the builder thought, and they are winding up going left of the trail after the dip.
"Well so what?" you might say as this picture shows all the plus's and minus signs show the drainage is working good, water going toward the drip. Well the problem is the area i show in the dots. That section where riders are winding up is a section of trail that does not have a firm tread base. The edge of the trail there had alot of duff mixed in, so after a while there will be a rut. More riders will deepen the rut as they come down fast off the downhill corner, and brake and skid on it, and it will get worse and worse as years go by.
So the solution is to make a bump on this section. Berms are fun, but are not necessary for flow. This bump puts a nice inward slope to the trail (inslope). Generally you want to avoid inslopes because they prevent water from shedding off the trail, but in this case it's on the high side of the dip, so water drains fine. The dotted lines again show the common path of mt. bikers, only now the bump is there to help get the wheels back to the center of the trail with no trail damage done. This is an example of "flow", when speaking of the relationship of how a trail rides and responds to wheeled traffic.
A look from the other side. Dotted lines show path of bikes as they come around the downhill corner up from the drainage dip, and now onto this bump. The bucket shows the level of the inslope.
Ok let's examine how to make a bombproof bump. First after digging out duff to get down to the hardpack pack i piled up a nice pile of softball sized stones for a base. You can think of this like a skeleton.
Next we dump a pile of crushed gravel. The gravel will fill inbetween the rocks settling them in, as well as create the basic shape of the bump. You can think of this like a the cartiledge and tendons.
Ok this part is a bit overkill but i still was close enough to harvest this really nice rocky soil. So we can think of this step as adding extra muscle, we're giving this bump tread some steroids. Think of this as the muscle.
And a final "skin" layer of mineral soil, pack it down, and you have a solid tread that should last forever.
Ok the final problem we see has a combination of all these issues. After a downhill we have a dip drainage that is not draining well, and the arrow points to the log which is creating a visual obstacle which is pushing riders to the outside of the trail. The outer part of this bench was built over duff and organic and is breaking down on this climb.
So we show a puddle developing on the trail, the trail now rides over ferns, and above the edge of the trail breaking down. This trail isn't even a half year old, so this section needed attention right away.
Dig out all the crud. Throw in a bunch of heavy rock and bury that with a wheelbarrow full of crushed gravel to reinforce the tread.
And after a nice topping of mineral soil we have a tread that looks and rides way better.
Taking some steps back viewing the entire climb, you'll see i used a pick to re-work the drainage as well as used that and a shovel to dig out the duff base. Then we can reshape and reinforce the tread with a couple loads of crushed gravel. All the signs are showing we're getting all the water off the trail now.
As our final shot shows that right above of the dip i added some inslope to help get the wheels centered on the trail. With our final topping of mineral soil we have an example of sustainably built singletrack trail that drains well, flows (rides) well, and will not suffer from erosion.
Cheers, now go dig!
