ADA 101 – Counter Slope
2010 ADAS 406.2 Counter Slope
Counter slopes of adjoining gutters and road surfaces immediately adjacent to the curb ramp shall not be steeper than 1:20, 5%. The adjacent surfaces at transitions at curb ramps to walks, gutters, and streets shall be at the same level.
Code according to 2010 ADAS. Check your state’s accessibility laws. Some states such as California, Georgia and Florida have additional requirements and standards.