2010 ADA Standards for Accessible Design Pocket Guide
1008.2.6 Ground Surfaces.
Ground surfaces on accessible routes, clear floor or ground spaces, and turning spaces shall comply with 1008.2.6.
Ground surfaces shall comply with ASTM F 1951 (incorporated by reference, see “Referenced Standards” in Chapter 1). Ground surfaces shall be inspected and maintained regularly and frequently to ensure continued compliance with ASTM F 1951.