Lee,
I purchased “Welcome to Pump Track Nation v2” a few months back and have designed my pump track to the point of painting it on the ground in my yard and prep’ing to dig. I’m at the point now of trying to find materials. I’m in SE Idaho where we have a lot of very fine silt/volcanic ash-based soil, which is great for potatoes, but bad for pump tracks.
I am finding that clay is very hard to come by. No local suppliers have any clay at all. I had a supplier that was supposed to bring me 40 yards of 80/20 baseball clay today but when he showed up it was 100% crushed red cinder (course sand), so I had to refuse the delivery.
I even called the local BMX track to see what they’re racing on and they told me the local dirt and if I found any clay in the area to let them know. They’re going to seal their track next year.
So I’m kind of at a loss as to what to do at this point and would like some advice from someone who’s built a few tracks. I don’t want to abandon my plans for the track, especially since I’ve promised one to my kids, but I also don’t want to waste my time and money on something that just won’t work in this area.
What guidance do you have if I have to use the local high silt content soil in my track? Am I going to have to use SoilTac or something similar?
Thanks
Jared S.
Hi Jared,
Thanks for reaching out. If you follow the design guidelines in Welcome to Pump Track Nation v2 and execute the plan with the right material, the track will ride well.
Emphasis on the right material.
Clay holds your track together. UCI spec for the top coating of a BMX track is 80% clay, 20% sand. The tracks and jumps you see with perfectly sculpted shapes are often “clay loam” with 60% clay and low silt content.
Silt makes the dirt very hard to pack. While the coarse angularity of sand creates mechanical locking, and clay’s negative charge binds with water, the smooth roundness of silt makes it structurally weak.
Oh man I just remembered this one city build. The manager promised the dirt met my spec. Back then I was fresh and trusting. I flew out there, placed the dirt, shaped it, then tried to pack it. No dice. The wet material shifted and sheared like mush, then it dried into powder. Turns out the dirt supplier tried to pull a fast one. I went out to the yard PISSED! and got us some proper dirt.
The best advice I have for building a pump track with silt-based dirt is don’t do it. Building a track in your yard takes significant space and time. It’s a shame when the track is rendered unrideable by poor planning, bad design, shoddy execution or, saddest of all, the wrong material.
The Pump Track Nation Code of Ethics requires me to say that. Now here are some viable options:
