Why does the Town clean vegetation in roadside ditches?
We have an annual ditching program to deal with drainage improvements. If the roadside ditch is a municipal drain, it is under the jurisdiction of the local municipality. Ditches are cleared along the roadside to increase the water flow as well as allow for adequate drainage for such things as rainfall or snow load. This includes widening & deepening ditches to handle the increased load.
Why does the Town only clear certain roadside ditches of snow in the spring?
Roadside ditches are cleared at the outlet end of the ditch system to provide positive drainage for the spring melt. Municipal crews prioritize known critical areas that experience buildup & attempt to minimize the risk of flooding. The clearing operations are not designed to drain all
ditches of spring melt water.
Why Are Road Ditches Important?
Protecting the road:
The main purpose of a roadside ditch is to protect the integrity of the road. Roads are designed to drain rain and snowmelt away from the road, toward the lower elevation of the roadside ditch.
Once the water reaches the ditch, it can flow along the ditch and eventually away from the roadway, protecting the stability of the road subgrade. When the ditch flow is blocked, water seeks a new course. Heavy water flow can carve a new path causing banks to erode or a
channel to deepen. This is why roadway grading practices are followed to prevent washouts & allow the water to run off the roadway into the adjacent ditches.
Roadway Base Drainage
Another purpose of a roadway drainage ditch is to drain water from under the roadway. The base is the foundation for supporting the load of traffic on the asphalt roadway. If water becomes trapped in the base, it weakens the structure of the roadway, leading to premature failure of the roadway. In addition, during cold weather, freezing and thawing of water trapped in the base under the pavement causes rapid deterioration of the pavement. An open ditch of sufficient depth provides continuous drainage of the base. Deep roadside ditches are often found throughout wet areas to mitigate this problem.
Flood Reduction
An open ditch has more capability than a piped system to reduce flooding resulting from heavy rainfall. During an extreme rainfall event, flow in a roadway drainage ditch is usually limited by driveway culverts or water elevations at discharge points, such as intercepting streams. When that happens, each roadway ditch becomes a small detention basin, storing excess water until discharge capacity becomes available. Another positive impact of these roadside ditches is that
they allow for the storage of excessive snow load which accumulates over the winter months.
Size & depth of the ditch play a factor when dealing with snow accumulation as it allows the snow load to be off the roadway/shoulder & gives the snow an unobstructed path to thaw, not affecting the roadway.
Ditch Maintenance
It is important that all Township Ditches be kept clear of obstructions that would impede the flow of water:
- Please do not dump grass clippings, leaves or other debris into/or adjacent to storm water ditches, channels or swales.
- At times, natural obstructions such as trees or tree limbs, beaver dams & brush may fall into ditches. These obstructions, if left unattended, may cause a ditch to become clogged and overflow.
- Please report any dumping or obstructions in Township ditches to the Public Works Department at 705-776-2659.
