To install a culvert, dig a sloped trench in the desired location, place a base of compacted gravel in the bottom of the trench, set the culvert into place and cover the culvert with compacted gravel. Measuring from ground level, cover the culvert with 6 inches of material.
Before digging, obtain the required permits and determine the location of buried utility wires on the property. Dig a trench that is deep enough to allow for both the base and covering materials. A combination of compacted gravel and asphalt can be used to cover the culvert.
Using 3/4 to 2 1/2-inch gravel mix, place a 2 1/2-inch deep layer of gravel in the bottom of the trench, and use a vibrating compactor to compact it. Add another 2 1/2-inch layer of gravel, compact it, and check the slop of the trench with a level.
Set the culvert into place, add a 6-inch layer of 3/4 ti 1-inch sized gravel mix lengthwise along one side of the culvert, and compact the gravel. Repeat the process on the other side of the pipe. Continue to add and compact 6-inch layers of the gravel mix on alternating sides of the culvert until the culvert is covered. Place a layer of 3/4 to 2-inch gravel mix on top of the culvert, and cover with asphalt if desired.