Trails in Wet Areas (continued)

Rock culverts offer a chance to display some real trail skills. Begin by laying large, flat stones in a deep trench to form the bottom of the culvert. In some installations, these bottom rocks may not be necessary. Then install large, well–matched stones along either side of the trench. Finally, span the side rocks with more large, flat rocks placed tightly together, enough to withstand the expected trail use. Cover the top rocks with tread material to hide and protect the culvert. These culverts, too, need to be large enough to clean out easily. The rocks should not wiggle (Figure 31).

Figure 31—Rock culverts may also have stones
laid along the bottom of the culvert. The perfect rocks
shown here are seldom found in nature, except reportedly
in Southwestern sandstone.

Water flowing toward a culvert often carries a lot of silt. If the water slows as it goes under the trail, the silt may settle out and clog the culvert. A good way to help prevent this from happening is to construct a settling basin at the inlet to the culvert (Figure 32). This is a pit at least 300 mm (1 ft) deeper than the base of the culvert. It can be lined with rocks as desired. The idea is that sediment will settle out here, where it is much easier to shovel away, rather than inside the culvert.

Figure 32—Settling basins help prevent culvert clogging.

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