Uncontrolled run-off from construction sites adversely impacts receiving waters. Sediment, one of the most significant pollutants from construction activities, can reduce the amount of sunlight reaching aquatic plants, clog fish gills, and smother aquatic habitat and spawning areas. Under the Construction Stormwater Control measure, the City of Ann Arbor has a regulatory program in place to control stormwater run-off from construction sites per
Chapter 63 of the Code of the City of Ann Arbor: Stormwater and Soil Erosion and Sedimentation Control.
A Grading/ Soil Erosion Permit (available from Planning and Development) is required when your project will result in greater than 225 square feet of "earth disturbance," or is located within 500 feet from the water's edge of a lake, wetland, or watercourse.
Earth disturbance should not be confused with the square footage of impervious surface proposed with the project. Earth disturbance is the area of the site that will be disturbed by the proposed activity including but not limited to: grubbing, grading, excavations, embankments, land development, road reconstruction, and the moving, depositing, stockpiling or storing of soil, rock, or earth materials.
Clearing more than 10,000 square feet of vegetative canopy, or disturbing a natural feature, also requires a valid grading permit.
Construction activities disturbing five acres or more, with a point discharge to the surface waters of the state, are required to submit a Notice of Coverage (NOC) to the Department of Natural Resources and Environment (DNRE) to obtain coverage under Permit-by-Rule. Prior to submitting the NOC, the permittee must obtain coverage under Part 91, Soil Erosion and Sedimentation Control (SESC), of the Natural Resources and Environmental Protection Act, 1994 PA 451, as amended, by obtaining an SESC permit from the City of Ann Arbor.
Regardless if the site is 5 or more acres or receives automatic coverage (1-5 acres), the permittee must comply with all requirements of Permit-by-Rule. One of the primary requirements of Permit-by-Rule is that all permitted sites must be inspected weekly and within 24 hours of a rain or snowmelt event that results in a discharge from the site. The inspections must be conducted and documented on an inspection report form or log by a certified stormwater operator trained and certified by the DNRE.
Common construction stormwater controls
The following are examples of construction stormwater controls commonly used in Ann Arbor. These controls are generally temporary, and are intended to keep construction site stormwater runoff from getting into the storm drain system.
Filters stormwater leaving site
Storm sewer inlet filter
Filters water entering storm sewer
Mud tracking mat
Releases sediment from vehicle tires prior to entering street
Provides suitable growing medium
Provides cover and moisture control for seeds
Straw erosion control blanket
Erosion control blanket
Holds soil in place until vegetation establishes