Gravel potholes develop for two primary reasons: Either the soil beneath the roadbed shifts, creating a void in the gravel, or the rounded crown of the gravel has leveled off or created a depression, allowing the collection of water. Either cause has the same repair process. You have to remove the affected gravel down to the soil beneath and then recreate the roadbed layer by layer, until you round off the top again. Though time-consuming, the result of the rebuilding process is worth the time, as the newly patched pothole is as strong as the surrounding road. As such, the repair area will likely last as long as the remaining surface, as long as regular maintenance occurs.
Remove the gravel surrounding the pothole to a distance of about 6 inches from the edge of the pothole using a shovel. Dig down to the dirt beneath the gravel road, setting the gravel taken from the area aside for reuse.
Tamp the dirt beneath the cleared area with a tamper to compress the soil. This will prevent further sinking in the soil from causing a return of the pothole.
Refill the pothole with the gravel taken from the area using the shovel. Layer the gravel in the sunken area by grade, matching the gravel size poured into the pothole with the gravel size in the layer surrounding the pothole in the rest of the road. Compress each layer of gravel sizes with the tamper before adding the next layer of smaller sized gravel.
Shape the top layer of gravel to match the crown shape of the rest of the gravel road using a rake. The crown shape is one in which the gravel on the roadbed rises slightly higher in the center than at the sides to aid in drainage. Rake the gravel into place then compress the entire section of road surrounding the pothole as well as the filled pothole itself with the tamper to avoid having different compression of the road across the roadbed.