Use a trowel or shovel to scoop up some extra soil from your yard and pour it into a bucket. Pick up extra soil from a home service center if you do not have enough spare soil available.
Pick up a few bags of coarse gravel for a home service center. Purchase more gravel than you may consider necessary, since it is difficult to gauge the depth of the chipmunk holes from the surface.
Pour gravel down the chipmunk holes to fill them in, leaving a 2 to 3 inch space leading to the lawn's surface. Chipmunks cannot easily dig through gravel, and will most likely not attempt to re-dig the hole.
Use your trowel or shovel to fill in the remaining space and the area leading up to the lawn with soil. Allow the fresh soil to pile at least 1 inch above the surface to create a mound.
Use your shovel to tamp down the soil. This will compact it, make it less noticeable and less hazardous for human travelers to walk on.