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Roads,
Skid Trails, Landings, and Stream Crossings |
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Stream
Crossings |
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Select a site for a stream crossing before the
rest of the road system is laid out or planned. This will allow the road
system to be designed for the best approach to the stream crossings. The
profile of a streambed should not be changed when constructing crossings.
Alteration of the stream banks should be minimized and a permit is required
prior to any work being done. All stream crossings should be done at right
angles to the stream channel to minimize disturbance to vegetation, banks
and streambed. Fords, culverts or bridges are most commonly used for stream
crossings. |
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Fords |
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A ford is simply a crossing of a stream without
a structure or culvert. They can be used where stream banks are low and
firm, the streambed is firm and the stream is shallow. Fords should not
be used if significant alteration of the stream bank is required. Rock and
gravel may be used to stabilize the streambed and approaches. Concrete may
be placed in streambeds or flow areas of intermittent watercourses when
warranted to protect the streambed under all weather conditions. |
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Bridges |
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Bridges can be used for temporary or permanent
crossings of streams. Usually, permanent bridges are used for larger streams
or for more permanent roads. Temporary bridges are used for smaller streams,
infrequent or one-time access and can be made of other suitable materials
or devices. Use care to minimize disturbance to stream banks and approaches.
A permit is required for any stream bank alteration.
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Culverts |
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Culverts are the most commonly-used form of stream
crossing. A culvert is easily placed, functions well and can be reused upon
removal when no longer needed. There are several important considerations
when using culverts for stream crossings. |
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- Use adequate size for stream and runoff flow. Anticipate storm peak
flows and size culverts accordingly.
- Stream gradients should not be changed when installing culverts.
- Protect fill over culvert by armoring upstream end of culvert.
- Provide armor of some type to prevent erosion at discharge end of
culvert.
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- Culverts should be placed slightly below the natural stream bed to
preclude culvert outfall barriers.
- Culverts should be installed with the same slope of the natural stream
bed. A pitch of 2-3 percent will cause the culvert to be self-cleaning.
- Culverts should be extended at least one foot beyond the fill at
both the inlet and outlet ends.
- Culverts need to be inspected regularly and cleaned out as necessary.
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