When rills and gullies deeper than 9 inches form in areas that have been backfilled, graded and vegetated, the rills and gullies shall be refilled, graded or otherwise stabilized and the area reseeded or replanted.
25 Pa. Code § 88.120
This section cited in 25 Pa. Code § 88.381 (relating to general requirements); and 25 Pa. Code § 88.493 (relating to minimum environmental protection performance standards).