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BMP C107: Construction Road/Parking Area Stabilization
Purpose Stabilizing subdivision roads, parking areas, and other onsite vehicle
transportation routes immediately after grading reduces erosion caused by
construction traffic or runoff.
Conditions of Use Roads or parking areas shall be stabilized wherever they are
constructed, whether permanent or temporary, for use by construction
traffic.
Fencing (see BMPs C103 and C104) shall be installed, if necessary, to
limit the access of vehicles to only those roads and parking areas that
are stabilized.
Design and
Installation
Specifications
On areas that will receive asphalt as part of the project, install the first lift as
soon as possible.
A 6-inch depth of 2- to 4-inch crushed rock, gravel base, or crushed
surfacing base course shall be applied immediately after grading or
utility installation. A 4-inch course of asphalt treated base (ATB) may
also be used, or the road/parking area may be paved. It may also be
possible to use cement or calcium chloride for soil stabilization. If
cement or cement kiln dust is used for roadbase stabilization, pH
monitoring and BMPs are necessary to evaluate and minimize the
effects on stormwater. If the area will not be used for permanent roads,
parking areas, or structures, a 6-inch depth of hog fuel may also be
used, but this is likely to require more maintenance. Whenever
possible, construction roads and parking areas shall be placed on a firm,
compacted subgrade.
Temporary road gradients shall not exceed 15 percent. Roadways shall
be carefully graded to drain. Drainage ditches shall be provided on each
side of the roadway in the case of a crowned section, or on one side in the
case of a super-elevated section. Drainage ditches shall be directed to a
sediment control BMP.
Rather than relying on ditches, it may also be possible to grade the road
so that runoff sheet-flows into a heavily vegetated area with a well-
developed topsoil. Landscaped areas are not adequate. If this area has at
least 50 feet of vegetation, then it is generally preferable to use the
vegetation to treat runoff, rather than a sediment pond or trap. The 50
feet shall not include wetlands. If runoff is allowed to sheetflow through
adjacent vegetated areas, it is vital to design the roadways and parking
areas so that no concentrated runoff is created.
Storm drain inlets shall be protected to prevent sediment -laden water
entering the storm drain system (see BMP C220).
Maintenance
Standards
Inspect stabilized areas regularly, especially after large storm events.
Crushed rock, gravel base, hog fuel, etc. shall be added as required to
maintain a stable driving surface and to stabilize any areas that have
eroded.
Clearing & Grading Development Standards Page 91
Following construction, these areas shall be restored to pre -construction
condition or better to prevent future erosion.