Water: Coastal Zone Act Reauthorization Amendments
D. Road Management
- Avoid using roads where possible for timber hauling or heavy traffic during wet or thaw periods on roads not designed and constructed for these conditions.
- Evaluate the future need for a road and close roads that will not be needed. Leave closed roads and drainage channels in a stable condition to withstand storms.
- Remove drainage crossings and culverts if there is a reasonable risk of plugging or failure from lack of maintenance.
- Following completion of harvesting, close and stabilize temporary spur roads and seasonal roads to control and direct water away from the roadway. Remove all temporary stream crossings.
- Inspect roads to determine the need for structural maintenance. Conduct maintenance practices, when conditions warrant, including cleaning and replacement of deteriorated structures and erosion controls, grading or seeding of road surfaces, and, in extreme cases, slope stabilization or removal of road fills where necessary to maintain structural integrity.
- Conduct maintenance activities, such as dust abatement, so that chemical contaminants or pollutants are not introduced into surface waters to the extent practicable.
- Properly maintain permanent stream crossings and associated fills and approaches to reduce the likelihood (a) that stream overflow will divert onto roads, and (b) that fill erosion will occur if the drainage structures become obstructed.
This management measure pertains to lands where silvicultural or forestry operations are planned or conducted. It is intended to apply to active and inactive roads constructed or used for silvicultural activities.
Under the Coastal Zone Act Reauthorization Amendments of 1990, States are subject to a number of requirements as they develop coastal nonpoint source programs in conformity with this measure and will have some flexibility in doing so. The application of this management measure by States is described more fully in Coastal Nonpoint Pollution Control Program: Program Development and Approval Guidance, published jointly by the U.S. Environmental Protection Agency (EPA) and the National Oceanic and Atmospheric Administration (NOAA) of the U.S. Department of Commerce.
The objective of this management measure is to manage existing roads to maintain stability and utility and to minimize sedimentation and pollution from runoff-transported materials. Roads that are actively eroding and providing significant sediment to waterbodies, whether in use or not, must be managed. If roads are no longer in use or needed in the foreseeable future, an effective treatment is to remove drainage crossings and culverts if there is a risk of plugging or failure from lack of maintenance. In other cases (e.g., roads in use), it may be more economically viable to periodically maintain crossing and drainage structures.
Sound planning, design, and construction measures often reduce the future levels of necessary road maintenance. Roads constructed with a minimum width in stable terrain, and with frequent grade reversals or dips, require minimum maintenance. However, older roads remain one of the greatest sources of sediment from forest land management. In some locations, problems associated with altered surface drainage and diversion of water from natural channels can result in serious gully erosion or landslides. After harvesting is complete, roads are often forgotten. Erosion problems may go unnoticed until after there is severe resource damage. In western Oregon, 41 out of the 104 landslides reported on private and State forest lands during the winter of 1989-90 were associated with older (built before 1984) forest roads. These landslides were related to both road drainage and original construction problems. Smaller erosion features, such as gullies and deep ruts, are far more common than landslides and very often are related to road drainage.
Drainage of the road prism, road fills in stream channels, and road fills on steep slopes are the elements of greatest concern in road management. Roads used for active timber hauling usually require the most maintenance, and mainline roads typically require more maintenance than spur roads. Use of roads during wet or thaw periods can result in a badly rutted surface, impaired drainage, and excessive sediment leading to waterbodies. Inactive roads, not being used for timber hauling, are often overlooked and receive little maintenance. Many forest roads that have been abandoned may be completely overgrown with vegetation, which makes maintenance very difficult.
Figure 3-24 illustrates some differences between a road with a well-maintained surface, good revegetation, and open drainage structures, and a poorly maintained road.
3. Management Measure Selection
a. Effectiveness Information
Drainage structures must be maintained to function properly. Culverts and ditches must be kept free of debris that can restrict water flow. Routine clearing can minimize clogging and prevent flooding, gullying, and washout (Kochenderfer, 1970). Routine maintenance of road dips and surfaces and quick response to problems can significantly reduce road-caused slumps and slides and prevent the creation of berms that could channelize runoff (Oregon Department of Forestry 1981; Ontario Ministry of Natural Resources, 1988).
Proper road/trail closure is essential in preventing future erosion and sedimentation from abandoned roads and skid trails. Proper closure incorporates removal of temporary structures in watercourses, returning stream crossing approaches to their original grades, revegetating disturbed areas, and preventing future access (Kochenderfer, 1970; Rothwell, 1978) Revegetation of disturbed areas protects the soil from raindrop impact and aids soil aggregation, and therefore reduces erosion and sedimentation (Rothwell, 1978).
b. Cost Information
Benefits of proper road maintenance were effectively shown by Dissmeyer and Frandsen (1988). Maintenance costs for road repair were 44 percent greater without implementation of control measures than for installation of BMPs
Dissmeyer and Foster (1987) presented an analysis of the economic benefits of various watershed treatments associated with roads (Table 3-32). Specifically, they examined the cost of revegetating cut-and-fill slopes and the costs of various planning and management technical services (e.g., preparing soil and water prescriptions, compiling soils data, and reviewing the project in the field). These costs were compared to savings in construction and maintenance costs resulting from the watershed treatments. Specifically, savings were realized from avoiding problem soils, wet areas, and unstable slopes. The economic analysis showed that the inclusion of soil and water resource management (i.e., revegetating and technical services) in the location and construction of forest roads resulted in an estimated savings of $311 per kilometer in construction costs and $186 per kilometer in maintenance costs.
As part of the Fisher Creek Watershed Improvement Project, Rygh (1990) examined the various costs of ripping and scarification using different techniques. The major crux of Rygh's work was to compare the relative advantages of using a track hoe for ripping and scarification versus the use of large tractor-mounted rippers. He found track hoes to be preferable to tractor-mounted rippers for a variety of reasons, including the following:
- A reduction in furrows and resulting concentrated runoff caused by tractors;
- Improved control over the extent of scarification;
- Increased versatility and maneuverability of track hoes; and
- Cost savings.
Rygh estimated that the cost of ripping with a track hoe ranged from $220 to $406 per mile compared to a cost of $550 per mile for ripping with a D7 or D8 tractor (Table 3-33).
As discussed more fully at the beginning of this chapter and in Chapter 1, the following practices are described for illustrative purposes only. State programs need not require implementation of these practices. However, as a practical matter, EPA anticipates that the management measure set forth above generally will be implemented by applying one or more management practices appropriate to the source, location, and climate. The practices set forth below have been found by EPA to be representative of the types of practices that can be applied successfully to achieve the management measure described above.
- Blade and reshape the road to conserve existing surface material; to retain the original, crowned, self-draining cross section; and to prevent or remove berms (except thosedesigned for slope protection) and other irregularities that retard normal surface runoff (Larse, 1971).
Ruts and potholes can weaken road subgrade materials by channeling runoff and allowing standing water to persist (Rothwell, 1978). Periodic grading of the road surface is necessary to fill in wheel ruts and to reshape the road (Haussman and Pruett, 1978). Maintenance practices must be modified for roads with broad-based dips (Swift, 1985). Maintenance by a motor grader is difficult because scraping tends to fill in the dips, the blade cannot be maneuvered to clean the dip outlet, and cut banks are destabilized when the blade undercuts the toe of the slope. Small bulldozers or front-end loaders appear to be more suitable for periodic maintenance of intermittent-use forest roads (Swift, 1988).
- Clear road inlet and outlet ditches, catch basins, culverts, and road-crossing structures of obstructions (Larse, 1971).
Avoid undercutting backslopes when cleaning silt and debris from roadside ditches (Rothwell, 1978). Minimize machine cleaning of ditches during wet weather. Do not disturb vegetation when removing debris or slide blockage from ditches (Larse, 1971; Rothwell, 1978). The outlet edges of broad-based dips need to be cleaned of trapped sediment to eliminate mudholes and prevent the bypass of stormwaters. The frequency of cleaning depends on traffic load (Swift, 1988). Clear stream-crossing structures and their inlets of debris, slides, rocks, and other materials prior to and following any heavy runoff period (Hynson et al., 1982).
- Maintain road surfaces by mowing, patching, or resurfacing as necessary.
Grassed roadbeds carrying fewer than 20-30 vehicle trips per month usually require only annual roadbed mowing and periodic trimming of encroaching vegetation (Swift, 1988).
- Remove temporary stream crossings to maintain adequate streamflow (Hynson et al., 1982).
Failure or plugging of abandoned temporary crossing structures can result in greatly increased sedimentation and turbidity in the stream, and channel blowout.
- Wherever possible, completely close the road to travel and restrict access by unauthorized persons by using gates or other barriers (Haussman and Pruett, 1978).
Where such restrictions are not feasible, traffic should be regulated (Rothwell, 1978).
Install or regrade water bars on roads that will be closed to vehicle traffic and that lack an adequate system of broad-based dips (Kochenderfer, 1970).
Water bars will help to minimize the volume of water flowing over exposed areas and remove water to areas where it will not cause erosion. Water bar spacing depends on soil type and slope. Table 3-34 contains suggested guidelines for water bar spacing. Water should flow off the water bar onto rocks, slash, vegetation, duff, or other less erodible material and should never be diverted directly to streams or bare areas (Oregon Department of Forestry, 1979a). Outslope closed road surfaces to disperse runoff and prevent closed roads from routing water to streams.
- Revegetate to provide erosion control and stabilize the road surface and banks.
Refer to Revegetation of Disturbed Areas management measure for a more detailed discussion.
- Replace open-top culverts with cross drains (water bars, dips, or ditches) to control and divert runoff from road surfaces (Rothwell, 1978; Haussman and Pruett, 1978).
Open-top culverts are for temporary drainage of ongoing operations. It is important to replace them with more permanent drainage structures to ensure adequate drainage and reduce erosion potential prior to establishment of vegetation on the roadbed.
- Periodically inspect closed roads to ensure that vegetational stabilization measures are operating as planned and that drainage structures are operational (Hynson et al., 1982; Rothwell, 1978). Conduct reseeding and drainage structure maintenance as needed.