Road Surface Maintenance
Road surfaces should be reworked only as necessary to provide a smooth running surface and a good crown or slope for drainage. All-season roads will require continual monitoring for surface and subgrade wear or deterioration. Rutting and loss of ballast often occur during rainy season use. Snow removal equipment can also destroy the road surface by removing or altering the crown and removing ballast. A plan should be in place to provide ballast when necessary to maintain continued use of the road.
On non-surfaced roads, a grader on the first pass should move material from the shoulder to a windrow in the center of the roadway. On the second pass, the blade should be centered on the windrow and continue working along the roadway. The blade should be adjusted so as to provide a slight slope or crown and should avoid cutting too deep into the road surface. Any excess material should be stored in the berm--not sidecast over the edge of the fill.
A wide variety of chemicals are commonly used to treat road surfaces to minimize wear, reduce dust, or de-ice. However, many of these products provide only minimal benefit and represent a potential hazard to water quality (US Environmental Protection Agency, 1975). Oil based dust palliatives must be used very carefully where the potential for entering surface or groundwater exists. Likewise, salts such as sodium chloride (NaCI) and calcium chloride (CaCl2), along with additives to prevent caking, rust, and corrosion, can cause acute and chronic toxicity in aquatic organisms and fish, contamination of groundwater supplying public and domestic water users, and death to vegetation adjacent to the road. Maximum salt concentrations can be found at soil surfaces nearest the road, but because they can be readily leached, salts can easily enter groundwater. High concentrations of salts have been found in streams during dry season low flows when the major component contributing to stream flow consists of groundwater.
Sulfite waste liquor from pulping operations is used extensively for dust abatement, however, it too has a potential for adversely impacting water quality through its high biochemical oxygen demand. Fortunately, though, the BOD-containing agents in pulping liquors will oxidize rapidly on the road surface. Controlled application during dry weather to prevent runoff will minimize impacts.
Herbicides used to control roadside vegetation represent the final class of road maintenance compounds that present a potential health or water pollution hazard if used incorrectly. Compounds such as dioxin, contained in 2,4-D and 2,4,5-T, are extremely toxic even in minute quantities.
Practices and methods to help minimize impacts from road chemicals include:
control application. Use only as much chemical as needed, both in concentration and rate of application, to provide the desired effect. Chemical manufacturers provide detailed information on the label of the container concerning dilution requirement, application rate and method, worker safety precautions, spill cleanup procedures, and other useful information. Be aware of weather conditions. Do not apply chemicals immediately prior to or during rainfall. Provide adequate training, performance standards, and supervision of application personnel and equipment. Perform trial applications to determine if calculated application rate is adequate. Keep records of chemical compounds used, the target species identified, concentration and application rates, vegetative growth stage (pre- or post-emergent), any unusual vegetative or environmental factors present during the application, and results of the application.
Use extra caution near streams. Avoid applying chemicals where the road crosses a channel and for 20 m (60 ft) on either side. If necessary, provide a filter strip between the road and the stream. Prevent spillage near or into streams. Do not, under any circumstances, discharge unused chemical into a stream.
Disposal of excess chemical and container treatment. Clean and rinse equipment and storage containers in an area where waste water can be safely collected and treated. If necessary, collect and ship excess hazardous chemicals to an authorized hazardous waste disposal facility.