Gravel Road

Program Practices

Worksites

A worksite is an identified portion of a road that impacts water quality. The Program has both paved Low Volume Road (LVR) worksites and Dirt and Gravel (D&G) worksites. A worksite has an identified beginning and end that demarks the limits of the section of road impacting the stream and other water bodies. The Program uses worksites to insure project funding is focused only on those sections of road that impact water quality. The areas outside of worksites may be in need of repair or be generating sediment, but do not have a direct connection to a stream or water body (typically on higher ground away from water).

Conservation districts have identified over 16,000 D&G worksites statewide on unpaved roads. The majority of these D&G worksites were identified in statewide “assessments” completed in 2000 and 2008. These assessments also evaluated each worksite according to the “pollution potential” on the site and provided it with a score. Conservation districts may use this assessment score in their application rankings. Worksites have also been added over time as needed. Conservation districts may add worksites to their inventory at any time. Worksites range in size from a single stream crossing to over a mile in length. The average D&G worksite size funded in the first 17 years of the Program is 0.45 miles in length.

Because the LVR portion of the Program is new, there is no established database of LVR worksites. LVR worksites should be identified by applicants and confirmed by the conservation districts using similar principles as the D&G worksites (identifying limits of water quality impact).


Environmentally Sensitive Maintenance (ESM)

Environmentally Sensitive Maintenance (ESM) is a term used to describe a suite of principles and practices that are designed to create a more environmentally and financially sustainable public road system. They are long term practices designed to reduce erosion and maintenance within the road area.

Long-term environmental benefits are achieved by attempting to “restore natural drainage” to a state similar to how it was before the road existed. In contrast to traditional “stormwater systems” that are designed to collect and convey large volumes of runoff, ESM practices focus on diffusing flow at the source, encouraging infiltration and reducing concentrated flow volumes. Environmental benefits of this approach to waterways include reduced sediment and other pollutant delivery, and reduced flood flows by “disconnecting” the road drainage system.

Long-term financial benefits are achieved because the same forces of erosion that cause environmental damage translate into increased maintenance costs as well. Every time a road, ditch, or bank washes out, it requires a large time and money investment by the local road owning entity. Some ESM practices may have higher than average up-front costs, but they save money over their lifetime by reducing future maintenance needs and costs.


ESM Principles

  • Avoid concentrating drainage where possible

  • Minimize Flow Volumes

  • Reduce effects of concentrated drainage

  • Reduce surface erosion

  • Reduce cost and frequency of road maintenance


Example EMS Practices

The following is a very brief summary of some of the Program’s most common ESM practices taught in the two-day ESM training course:

  • Road/Stream Interactions: ESM practices for stream crossings focus on reducing the sediment delivery to the stream, stream stability issues, and the stream crossing itself. Practices such as highwater bypasses, French mattresses, proper stream crossing sizing, better bridge and pipe design, and in-stream flow control structures can be effectively used to stabilize the road/stream interface.

  • Road Surface: ESM practices for the road surface include drainage control and improved aggregate. Drainage control starts with proper crown and cross-slope, but also includes practices such as grade breaks, berm removal, and broad-based dips. Improved surface aggregate focuses on the Program’s Driving Surface Aggregate and includes maintenance concerns such as grading and pothole repair.

  • Road Base: Practices that improve the base of a road include mechanical base improvements, underdrains, French mattresses, and in some cases full-depth reclamation.

  • Vegetation management practices: Practices that manage vegetation in a sustainable manner will reduce erosion from the road area and save on future maintenance costs associated with tree trimming and cleanup. Practices include selective thinning, proper pruning, seeding and mulching, and managing vegetation for long term stability.

  • Road Bank management practices: Practices that stabilize the upslope or downslope road bank include slope reinforcement, filling the road profile, naturalizing bank shape, and natural or mechanical slope reinforcement.

  • Road Ditch and Outlet Stabilization: ESM practices for ditches include anything that reduces the flow in the ditch. The simplest of these practices is to provide more drainage outlets in the form of new turnouts and crosspipes. Selecting locations to outlet water and choosing the proper outlet stabilization methods is also important. Other practices such as berm removal and filling the road profile attempt to eliminate ditches completely and promote sheet flow. Practices to reduce the effect of subsurface flow such as underdrains are also important.

  • Off right-of way practices: Practices that start outside the road area in an effort to reduce the amount of water coming to the public road. Interceptor swales and bank benches reduce the amount of overland flow coming to the road. Driveways and access lanes are often large contributors of water to the public road and can be addressed by re-profiling or with surface control features such as grade breaks, water bars, or conveyor belt diverters.

  • Paved Low Volume Road Specific Practices: Low volume roads may require an added set of ESM practices, especially those located in urban areas where traditional drainage dispersal and infiltration practices may not be practical. LVR-specific practices will evolve over time, but should focus on making improvements to both the environment and the road.