Preparing your roads for winter

Off the coast of Latin America, a warming pattern is leading scientists to predict the strongest--and potentially most devastating--El Niño in more than half a century. El Niños bring wild storms to California, typically reaching the coast in late fall or winter. This year, federal forecasters are predicting that it will arrive sooner, perhaps as early as September.

You don't need a weatherman's predictions to know that fall is the season to work on erosion control and road maintenance. Before winter, all permanent, seasonal and temporary roads should be inspected and prepared for the coming rains. Winterizing consists of maintenance and erosion control work needed to drain the road surface, to ensure free flowing ditches and drains, and to open all culverts to their maximum capacity.

• On unsurfaced roads, waterbars may be required at spacings dictated by the road gradient and erodibility of the soil.
• Trash barriers, culvert inlet basins and pipe inlets should be cleaned of floatable debris and sediment.
• Ditches that are partially or entirely plugged with soil and debris should be cleaned and heavy concentrations of vegetation which impede ditch flow should be trimmed.
• Excavate all unstable or potentially unstable fills and sidecast which could fail and be delivered to a watercourse during the coming winter.
• Once seasonal and temporary roads have been winterized, they should be gated and closed to "nonessential" traffic.
• If maintenance activities produce excess material, it should be stored locally or hauled away. Spoil may be feathered over the road, but on permanent roads excess fine material may produce unwanted muddy conditions after the first rain. Spoil material should be hauled to a stable site safely distant from streams, contoured to disperse runoff and stabilized with mulch and vegetation. Excess spoil should never be sidecast near streams. Berms of excess spoil along the road shoulder should be removed or frequently breached prior to the rainy season.

Waterbars (also called waterbreaks) can be used to drain a road surface. These are shallow, abrupt excavated dips or troughs with an adjacent, downslope hump or moulded berm, that are built at an oblique angle across the road. Waterbars are useful only on low standard seasonal or temporary, unsurfaced roads where winter use will not occur, because traffic easily cuts through the soft berm and fills the adjacent dip.

Waterbars are high maintenance drainage structures that are prone to failure if not properly built and maintained. Unauthorized winter traffic is likely to break down waterbars and result in serious road surface erosion and water pollution.Waterbars are constructed on unsurfaced forest roads that will have little or no traffic during the wet winter period. The waterbar should be extended to the cutbank to intercept all ditch flow (1) and extend beyond the shoulder of the road. A berm (2) must block and prevent ditch flow from continuing down the road during flood flows. The excavated waterbar (3) should be skewed 30° to the ditch-line with the excavated material bermed on the downhill grade of the road (4). Water should always be discharged onto the downhill side on a stable slope protected by rip rap or vegetation (5). The cross ditch depth (6) and width (7) must allow vehicle crossover without destroying the function of the drain.

The information provided here came from the Handbook for Forest and Ranch Roads: A Guide for planning, designing, constructing, reconstructing, maintaining and closing wildland roads by William E. Weaver, Danny K. Hagans & Pacific Watershed Associates for the Mendocino County RCD, June 1994. This 190-page handbook is an excellent resource. Order it for $20 from: Mendocino Co RCD, 405 Orchard Ave, Ukiah, CA 95482; (707) 468-9223.