A cross section of a culvert at A-A shows the recommended structure of fill material installed around a culvert pipe. Culverts should be installed as the road work progresses. 1. Place debris and slash to be used as a filter system, if needed. Construct sediment ponds, if needed. Complete downstream work first, such as energy dissipating devices and large rock riprap.
Route stream around work area until pipe is installed.
Construct pipe inlet structure. Install culvert pipe. A culvert inlet should be placed on the same level as the stream bottom. In some instances where the culvert inlet has to be lower than the drainage gradient, a drop box can be constructed. This box, which is a place for sediment to settle out before water enters the culvert, needs frequent maintenance.