The sun is shining, the snow is melting, and spring is here. It’s
time to get out on the trails, right? Well actually wrong, it’s the opposite and
here’s why. Soils throughout the Interior pose a particular problem for
maintenance, being pre-dominantly thick layers of loessial silt. This
silt, even when it includes a high proportion of rock or gravel, loses all
cohesion when its moisture content approaches saturation level, a condition
achieved every spring, during this frozen to thawed phase.
As the upper layer thaws, snowmelt is trapped in it above the still
frozen zone, and until thaw has occurred at depth and sufficient moisture has
drained and evaporated out of it, the soil has no structural resistance to
traffic.
So before jumping on your ATV, horse, or bike here are some
guidelines. The tread must first become snow-free, then thaw, then lose enough
of the snow and melt water to achieve at least a moderate level of structural
integrity. My observations have
been that once the ground thaws 12 inches, the water is able to drain
sufficiently to allow for sustainable use. During breakup, Alaska State Parks
has a four-week closure on its multiple-use trails in the Chena River State
Recreation Area. The closure
normally runs from April 20th to the Thursday before
Memorial Weekend. This should give
you a pretty good idea when trails dry out sufficiently, although each year is
different. Last year we had
to wait until June 6th to
open.
If traffic is allowed too soon, the tread will churn and deeply
rut, which slows the drainage process and leaves the tread prone to
re-saturation during summer rains.
Trails in flatlands, where no tread is excavated, can handle some
early-season traffic because that traffic runs on a vegetative root mat
overlying the silt. However, once the root mat wears through, the saturated-silt
problem is immediately apparent and more serious, since drying is much
slower.
Achieving a balance between resource conservation and recreation
use is what good trail design and construction is all about.
Allowing trails to drain without significant disturbance for a short time
will assure good trails for all users the rest of the
year.
Brooks Ludwig is the park superintendent
for the Northern Area of the Alaska Division of Parks and Outdoor
Recreation
time to get out on the trails, right? Well actually wrong, it’s the opposite and
here’s why. Soils throughout the Interior pose a particular problem for
maintenance, being pre-dominantly thick layers of loessial silt. This
silt, even when it includes a high proportion of rock or gravel, loses all
cohesion when its moisture content approaches saturation level, a condition
achieved every spring, during this frozen to thawed phase.
As the upper layer thaws, snowmelt is trapped in it above the still
frozen zone, and until thaw has occurred at depth and sufficient moisture has
drained and evaporated out of it, the soil has no structural resistance to
traffic.
So before jumping on your ATV, horse, or bike here are some
guidelines. The tread must first become snow-free, then thaw, then lose enough
of the snow and melt water to achieve at least a moderate level of structural
integrity. My observations have
been that once the ground thaws 12 inches, the water is able to drain
sufficiently to allow for sustainable use. During breakup, Alaska State Parks
has a four-week closure on its multiple-use trails in the Chena River State
Recreation Area. The closure
normally runs from April 20th to the Thursday before
Memorial Weekend. This should give
you a pretty good idea when trails dry out sufficiently, although each year is
different. Last year we had
to wait until June 6th to
open.
If traffic is allowed too soon, the tread will churn and deeply
rut, which slows the drainage process and leaves the tread prone to
re-saturation during summer rains.
Trails in flatlands, where no tread is excavated, can handle some
early-season traffic because that traffic runs on a vegetative root mat
overlying the silt. However, once the root mat wears through, the saturated-silt
problem is immediately apparent and more serious, since drying is much
slower.
Achieving a balance between resource conservation and recreation
use is what good trail design and construction is all about.
Allowing trails to drain without significant disturbance for a short time
will assure good trails for all users the rest of the
year.
Brooks Ludwig is the park superintendent
for the Northern Area of the Alaska Division of Parks and Outdoor
Recreation
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