2019 California Standards for Accessible Design Guide (effective January 1, 2020 with July 1, 2021 amendments)

11B-406.5.8 Counter slope.

Counter slopes of adjoining gutters and road surfaces immediately adjacent to and within 24 inches (610 mm) of the curb ramp shall not be steeper than 1:20. The adjacent surfaces at transitions at curb ramps to walks, gutters, and streets shall be at the same level.

[2010 ADA Standards] 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. The adjacent surfaces at transitions at curb ramps to walks, gutters, and streets shall be at the same level.

FIGURE 11B-406.5.8 COUNTER SLOPE OF SURFACES ADJACENT TO CURB RAMPS