SITING AND DESIGN CONSIDERATIONS
Before grading activities begin, decisions must be made regarding the steepness of cut-and-fill slopes and how the slopes will be protected from runoff, stabilized, and maintained.
A grading plan should be prepared that establishes and includes:
• Identification of areas of the site to be graded
• How drainage patterns will be directed
• How runoff velocities will affect receiving waters.
• Information regarding when earthwork will start and stop
• The degree and length of finished slopes
• Where and how excess material will be disposed of (or where borrow materials will be obtained if needed).
• Berms, diversions, and other storm water practices that require excavation and filling should be incorporated into the grading plan.
A low-impact development BMP that can be incorporated into a grading plan is site fingerprinting, which involves clearing and grading only those areas necessary for building activities and equipment traffic. Maintaining undisturbed temporary or permanent buffer zones in the grading operation provides a low-cost sediment control measure that will help reduce runoff and off-site sedimentation. The lowest elevation of the site should remain undisturbed to provide a protected storm water outlet before storm drains or other construction outlets are installed.
Earthscapes Unlimited, Inc.
WHAT IS LAND GRADING?
Land grading involves reshaping the ground surface to planned grades as determined by an engineering survey, evaluation, and layout. Land grading provides:
• More suitable topography for buildings, facilities, landscaping and other land uses.
• Helps to control surface runoff, soil erosion, and sedimentation during and after construction.
Sites with uneven or steep topography or easily erodible soils, because it stabilizes slopes and decreases runoff velocity. Grading activities should maintain existing drainage patterns as much as possible.
LIMITATIONS TO CONSIDER
Improper grading practices that disrupt natural storm water patterns might lead to
• Poor Drainage • High Runoff Velocities
• Increased Peak Flows during storm events
Clearing and grading of the entire site without vegetated buffers promotes off-site transport of sediments and other pollutants. The grading plan must be designed with erosion and sediment control and storm water management goals in mind; grading crews must be carefully supervised to ensure that the plan is implemented as intended.
All graded areas and supporting erosion and sediment control practices should be periodically checked, especially after heavy rainfalls. All sediment should be removed from diversions or other storm water conveyances promptly. If washouts or breaks occur, they should be repaired immediately. Prompt maintenance of small-scale eroded areas is essential to prevent these areas from becoming significant gullies.
Land grading is an effective means of reducing steep slopes and stabilizing highly erodible soils when properly implemented with storm water management and erosion and sediment control practices. Land grading is not effective when drainage patterns are altered or when vegetated areas on the perimeter of the site are destroyed.