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 Camp
Roads: Why Do I Need to be Concerned?
If you have a dirt or gravel
road/driveway that leads to your house than you need to know about phosphorous
pollution. There is a good chance that your road is contributing phosphorous to
the lake. Phosphorus is a nutrient required for the growth of all plants,
including algae. When it rains, fine soil particles can be dislodged from your
road and washed into the lake. This is called stormwater runoff. Phosphorus
binds tightly to soil particles until it is washed into the lake. At this point
phosphorus can be problematic because aquatic vegetation can use it to grow,
reducing water clarity, recreational and aesthetic pleasure and in extreme cases
can cause algal blooms. There are other pollutants, which can reach your lake in
this manner as well. Gas, greases, oils, road salt,
and heavy metals that drip from your car can be transported to the lake by storm
water runoff.
In watershed surveys that we have
conducted all over the state of Maine, camp roads and driveways were found
to be the most important contributor of soil erosion entering tributaries
and lakes, adding to phosphorus and sediment pollution.
Roads require regular maintenance. Most roads with eroded surfaces are filled
with additional soil and gravel each year. We need to be mindful that this
new fill does not end up in the lake. Below are some ideas to help you
control road erosion and preserve your lake’s water quality.
All camp roads can create some risk to the lake, but roads that are long and
steep cause the most erosion problems. We have little control over how steep
the area is, but we can control how far water can run down a given stretch
of road. This combined with proper road shape, diversions, and quality of
road ditches will determine how much impact your road or driveway will have
on your lake.
Shape:
Your road should be higher in the middle and lower
on the sides to allow water to quickly runoff the road surface. This is
called crowning a road. In general there should be
approximately ½ inch of crown height per foot of lane width. An
experienced equipment operator should use a grader machine with a steel
cutting blade to ensure the road is maintained properly. If a crown is not
maintained properly water tends to rest on the road surface. If water rests
in tire ruts or potholes, suspended soil will be splashed from the road,
making the problem worse each time a vehicle drives over it. Also, a crowned
road will remain firmer during spring thaw.
Berms:
Mounds of soil that build up on the sides of
the road are called berms. Berms do not allow the water to flow directly off the
road surface. Storm water runoff will channel and eat away at the sides of your
road instead of flowing off into the ditches and into
a vegetated buffer. Berms are often created when the road grader pushes material
off to the sides of the road, or from winter sanding and plowing. Dragging a bed
of springs or using a bulldozer to grade the road readily creates berms.
Diversions:
A diversion such as a waterbar, dip or swale will
shed water off your road and into the ditch. If your road has water running
down it during rainstorms than you should think about installing some water
diversions. To construct a waterbar on a year-round road, a small mound, or
speed bump, is made from road soil across the width of the road at an angle
of 30 degrees. Seasonal roads can make a rubber water bar with conveyor belt
material found at some hardware stores. It is placed into the road
with about 3 inches protruding above which will divert the water into the
ditch. A swale is a wide shallow dip in the road; it can be rocked, seeded
or left as road surface.
Another idea to protect the surface of a seasonal
camp road is to seed it in the fall when you close down your camp. Rake the dirt
and scatter inexpensive annual rye grass seed over the surface. There is no need
to apply lime or other soil enhancers. Afterwards, mulch the road with hay. This
practice is not used very often, but if you only use your camp during the
summer, it could be a good approach to control runoff from fall rains and spring
snowmelt.
Ditches:
The condition of your
ditches is as important as the road itself. To keep road ditches from
eroding make sure the side slopes are not too steep. For every foot of
vertical rise, they should have a three-foot horizontal run. The gentle
slope reduces the potential for the sides to slump or cave into the
ditch. Grass the surfaces of the ditch. This will absorb water and slow
down the velocity of the runoff. If you are forced to have ditch
construction steeper than suggested, the sidewalls should be armored
with riprap rock and filter fabric to protect the banks from soil
erosion.
Ditch Turnouts:
Ditch turnouts make runoff easier to manage by getting the water out of the road
ditch and into a vegetated area. Soil particles settle out while water and
nutrients are taken up by the vegetation. A dam of crushed rock is placed in the
ditch to direct the water out into a vegetated buffer. The ditch should follow
this dam into the vegetated area. It should be constructed so that the runoff is
spread out into a thin sheet, not concentrated in a channel. By creating a thin
sheet, the runoff slowly percolates into the soil for use by the vegetation.
Ditch turnouts should be placed every 50 feet in the ditch. Check with abutting
property owners to make sure the water from the ditch turnout is not going to
adversely affect their property.
Other Considerations:
Make your road as narrow as
possible to decrease impervious surfaces. If there is less water running off
the road you will have fewer problems. Maintain your ditches and culverts by
cleaning them out in the spring and fall.
For your lake’s sake don’t
ignore chronic problems. Contact your local Soil and Water Conservation
District for more information and advice on road maintenance, their services
are often FREE.
Take the Road and Driveway
Self-Assessment.
Lake*A*Syst
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Last
Modified:
05/30/08
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