Q: The Blue Book mentions rutting on roads but not so much
about rutting in the harvest area. Are there BMP guidelines for rutting that
apply across the harvest area as well? What are the concerns for rutting in the
harvest area and how would you evaluate a site if you were conducting a
voluntary site evaluation?
A: Great question, and one that could
really use some clarification, especially as we move into the wet season!
Rutting
is one of those situations where everybody loses. A skidder slogging through
the mud certainly does not increase the efficiency of a logger’s operation, and
landowners know that extensive rutting can lead to erosion and soil compaction,
which can have a substantial impact on future tree growth. Rutting can also
lead to environmental and water quality issues, especially if it occurs on
steep slopes.
Rutting
generally results from the tires of vehicles such as skidders, log trucks, pickups,
ATVs, etc., operating under wet conditions. Most of the rutting occurring in
the harvest area (i.e., off the established roads) will be caused by skidder
traffic and to a lesser degree the shear. The BMP guidelines do not
specifically mention the shear, but it would be considered part of the skidding
operation since it travels over essentially the same area.
So, are
there guidelines that cover rutting in the harvest area? I think that question
can be answered by mentioning one point; skidding operations occur on skid
trails. Skid trails are defined as a route over which logs are moved to a
landing or road. So if a skidder passes over an area, any rutting that it
causes would be considered occurring on a skid trail, and therefore be
addressed by BMPs for skid trails. Make sense?
Rutting
on skid trails is covered under the recommended specifications for skid trails
in Part II of the Blue Book. The guidelines recommend that when soils are
saturated, skidding should be restricted to prevent excessive soil compaction
and channelized erosion. The general rule of thumb for determining excessive rutting
is no deeper than six inches for no more than 50 feet (or about two skidder
lengths). That comes from number 18 under the recommended specifications for
haul roads in your BMP Blue Book. Certainly
there are things you can do to minimize rutting during your operation. Using high flotation tires, keeping skidder
loads light, or shovel logging extremely wet sites are all possible options.
But,
don’t get the impression that when we do a site evaluation we come with ruler
and tape measure in hand ready to measure every rut we see. Remember that BMP
guidelines are for reducing impacts to water quality. When determining if
rutting is too extensive, there are several factors to consider. Look to see if
the ruts will change the direction of water flow, or cause it to puddle the
next time it rains. Soil type and slope are both very important factors to
consider. Look to see if the ruts will in some way channel rainwater so that it
may deliver sediment to a stream. If you notice these things happening, then it
may be time to head to drier ground. Our evaluations take the entire site into
consideration, so if it is obvious to us that you pulled off when you noticed
rutting started to occur, our evaluation will certainly reflect that.
For more
information on BMPs visit the Texas Forest Service webpage at http://txforestservice.tamu.edu/water,
contact me at (936) 639-8180.
* This article was published in the November 2010 issue of the Texas Logger
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