Download Road Survey Information Sheet

Road Survey
Why important: Soil erosion is the single largest pollutant (by volume) to our surface waters, and up to
85% of all erosion and sedimentation problems in lake watersheds originate from improper construction
and maintenance of camp roads.
Paved Roads:
 Generally state or town roads and not camp roads
 If a camp road is paved, it is a good indication that the houses along the road are year-round
residences.
 Paved roads generally cut down on the amount of phosphorus loading because they are not
comprised of loose dirt, but they still may serve as conduits for phosphorus-loading with the
water carrying dust and pavement particles toward the lake
Unpaved Roads:
 The majority of camp roads
 Generally made of gravel, hard packed dirt, or loose dirt
A good camp road has:
 Proper crowning
 Gravel or hard dirt surface
 No mounds of sediment known as berms bordering the road and preventing water runoff
 Proper road ditching
 Correct placement and size of culverts
 Functioning water diversions
Road Level
 Properly constructed roads are built above the natural ground. This is essential for effective
surface drainage.
 Unfortunately, many older camp roads were built by pushing material away from the roadway,
resulting in a road surface that was lower than the surrounding land.
Crowning:
 Crowning of the road is very important because crowning serves to direct water off the road
surface and into roadside ditches
 A good crown rises 0.5 inches for every foot of road width (a 12 ft. wide road should have a six
inch crown)
 Indents (such as tire marks) in road are signs of erosion
Ditching:
 Functions:
o Collect road surface run-off and drain it away from the road.
o Store large amounts of rainfall
o With turnouts, prevent pollution from reaching sensitive water resources
 Ditches need to accommodate the highest possible level of storm water and seasonal runoff
 As a general rule, water in a ditch should never be higher than 1 foot below the top of the ditch
 Berms are a common problem for ditching. Winter sand and other debris gets pushed to either
side of the road when it is plowed. This accumulates into long narrow piles which prevent water
from getting into the ditches. Storm water runoff will eat away at the sides of the road instead of
flowing off into the ditches and into a vegetated buffer.
 Placement:
o Need to be situated along roadsides where proper crowning can direct water into them
 Possible Shapes:
o U-Shaped
o V-Shaped
 Best ditches:
o U-shaped
o Clear of debris
o Lined with small stones (to slow the speed of the water) or vegetation (to absorb the
water and slow it down)
o Has several water diversions where flowing water can be channeled away from the lake
and into a well-buffered area. Water diversions are usually at bends in the roads.
 V-shaped ditches are bad because the shape helps to increase the velocity of the water and
increases erosion
U-shaped ditch
V-shaped ditch
Water diversion into forested area
Culverts:
 Used to convey water from one side of the road to the other
 Should be installed when:
o A stream, brook, or seasonal runoff channel must be directed under the road. This keeps
the road from disrupting the natural drainage system
o Surface water flows reach volumes that are difficult to contain in a roadside ditch and
need to be turned out on the opposite side of the road
o A driveway crosses a road ditch
 Proper maintenance of culverts is critical to their function. Their internal frame should be
complete and cleaned of debris and sediment
 A good culvert:
o Adequate width for managing seasonal and storm-water runoff
o Correct placement
o Free of debris
o Over a foot between the top of the culvert and the road surface
Good Culvert
Poor Culvert
Drainage Alternatives:
 Water bars
o A ridge (like a speed bump) that runs diagonally across the road, typically at a 30-degree
angle. The ridge stops the water from running down the road and diverts it to the side
o May be inappropriate for frequent (year-round) traffic
 Broad-based dip
o Accomplishes same result as a water bar by using a shallower depression
o More appropriate for year-round use but cannot be used on steep slopes
 Rubber bars
o Can be used to divert water off sloping sections of a road
o Protrudes above the ground surface high enough to intercept and collect water, while
allowing traffic to pass over it
o Generally used on seasonal roads or driveways because they are prone to snowplow
damage
 Open-top culverts
o Box-like structures that collect and divert road surface runoff away from the road
o Prone to snowplow damage