Roads typically are built with crowns in the middle to direct rainwater toward the sides. This prevents water from pooling on the driving surface. This water picks up petroleum products, rubber and other debris from the road as it washes down to the sides. Gravel berms can collect water and channel it to ditches, catch basins or other points for eventual delivery to wastewater treatment plants or natural retention areas.
Without proper road grading and berming, water would continue to move unchecked through grasslands, down slopes and into wetlands or bodies of water. Water movement causes erosion, which may cause unstable ground near the road and endanger drivers, pedestrians and nearby homeowners. Erosion also affects the way this runoff can be filtered, because ground that could potentially remove pollutants could be washed away.
Because state building codes leave it to local authorities to manage erosion control, the task generally falls to the city or county road engineer. In Concord, California, for example, the engineer enforces local ordinances and regulations by requiring construction companies to put up a surety bond. This cash holding equal to the amount expected to complete the project correctly gives the local government an assurance that the work will be done according to specs. Erosion control plans are taken on a case-by-case basis depending on the fragility of the environment where the project is taking place.
With such an emphasis placed on planning and execution, consultants like Pacific Watershed Associates (PWA) have offered training to local road officials on erosion control techniques. PWA says these best management practices satisfy the requirements or requests of water-quality boards, state wildlife authorities and the Army Corps of Engineers. A properly executed plan also provides safer conditions for humans, animals and the environment.
