Road and Trail Treatments

What – Altering road template.  Outsloping is accomplished with an excavator, dozer, and grader (the excavator pulls back fill and places the material in the ditch; the dozer assists in moving and reshaping the road profile; and the grader completes the final profile).

Purpose – Disperse water along fill slope and reduce erosion; prevent concentration of flow on road surface that would otherwise cause rill, gully, and rut erosion.

Effectiveness – No effectiveness monitoring data is available.  Informal observations indicate immediate and long-term facility and resource benefits, including less sediment delivered to stream channels and reduced road maintenance.  In areas with highly erodible soils, outsloping roads with unvegetated soils may increase erosion.  Outsloping is often combined with other road treatments, including rolling dips and armored crossings to control water.

Where

• Within areas of high- and moderate-burn severity where loss of control of water is a risk particularly on flat road grades (< 10%).

Cost – $2 per linear foot.  Additional factors include:

• Road prism shape (inslope or outslope)
• Size and extent of existing berm
• Presence and extent of vegetation

How to Link – See USDA BAER Catalog page 106 (PDF page 144).

What – Altering road template.

Purpose – Rolling dips are used to drain water effectively from the road surface and prevent concentration of water.

Effectiveness – No effectiveness monitoring data exists on rolling dips.  Rolling dips and outsloping are common treatments used to disperse flows and prevent stream diversion.  Rolling dips are constructed easily with a dozer but often are too short in length, or too shallow to contain the expected flows. Often, a rolling dip/water bar is armored and used instead of a culvert upgrade because of its relatively low cost.  However, it may erode away with strong currents in high discharge.

Where

• Roads with a continuous grade and infrequent drainage structures.
• Roads with grades less than 15 percent.

Cost – $390–1200 per dip.  Additional factors include:

• Production rates
• Amount of excavation and material movement
• Equipment necessary
• Armoring requirements

How to Links – See USDA BAER Catalog page 110 (PDF page 118); and additional illustrations.

What – Structures such as armored rolling dip, overside drain, or imbricated (overlapping) rock-level spreader. 

Purpose – Used on roads to control runoff across the road prism and to protect the road fill.   Armored rolling dips provide increased water flow capacity when hydrologic analysis indicates the current pipe size is too small for the short-term increased storm runoff created by fire.  Dips prevent stream diversion by safely channeling increased flows back into the channel.  Overside drains (berm drains and down drains) are placed in stream crossings where no culvert or armoring exists and in locations where the embankment (fill slope) needs protection.  Imbricated rock-level spreaders have been used on high standard roads including highways and county roads.  The imbricated rock-level spreader is a permanent structure that is built with large rock placed in a stairstep (shingled) design on excavated benches with either little or no grade along the revetment’s length.  The spreader protects the road fill from overland flows.

Effectiveness – Armored rolling dips are effective low-cost treatments when properly designed and implemented.  Qualitative monitoring data of armored rolling dips found erosion problems when the dip was too short and when insufficient riprap was used on the fill slope.  Overside drains fail if not properly designed, installed, and maintained.  Initial qualitative monitoring indicated imbricated rock-level spreaders (rock armored overflow) are effective when they discharge directly onto a vegetated/wooded zone.

Where

• Roads located below high-and moderate-burn severity areas.
• Road segments that have a long continuous grade and infrequent drainage.
• Roads that are insloped.

Costs – Treatment vary in cost. Cost estimates can be developed based on material and installation requirements.

How to Link – See USDA BAER Catalog page 115 (PDF page 123).

What – Culverts are temporarily removed and replaced with natural fords, vented ford pipes, and low water bridges during extreme runoff events. 

Purpose – To prevent stream diversion and keep water in its natural channel.  This prevents erosion of the road fill, reduces adverse effects to water quality, and maintains access to areas once storm runoff rates diminish.

Effectiveness – Ford crossings effectively eliminate loss of water control at road/stream crossing.  However, poor design or implementation can result in damage to infrastructure and reduced water quality.  Informal monitoring indicates that flexible structures adjust to changes and are not prone to undercutting.  Boulder or riprap structures are long enough to avoid being outflanked by high flows.  Jersey barriers are less effective as an endwall material since they are not flexible.

Where

• Roads crossing ephemeral or seasonally flowing channels.
• Culverts that are at risk of plugging and diverting from increased runoff and bedload.
• Road crossings where high sediment delivery is expected.
• Roads where water overtops the road continuously or intermittently during and following mild floods.

Costs – $500–2500 for an unvented ford; costs increase for a vented ford or low-water bridge.  Additional factors include:

• Amount of material to be moved from stream channel
• Amount of riprap required to armor exposed and erodible slopes
• Location
• Depth of fill or embankment

How to Link – See USDA BAER Catalog page 122 (PDF page 122).

(Before modification)

(After modification)

What – Culvert modification addresses flooding and debris concerns as a result of fire.  Usually involves upgrading the culvert size for increased runoff and associated bedload and debris. 

Purpose – By increasing the flow and debris passage capacity, road damage is prevented or reduced.

Effectiveness – Evaluation of this treatment is only qualitative.  The treatment rates ‘well’ when new culverts are installed prior to the first rains.  ‘Poor’ ratings reflect the inability to perform the upgrade in a timely manner or when culverts are still not large enough to handle runoff events.

Where

• High-burn severity watersheds.
• Drainages with undersized culverts.
• Road access is required.

Costs – $20,000 to $150,000 per structure.  Additional factors include:

• Culvert size (diameter and length) and type
• Site location and access
• Fill (removal and replacement)
• Headwall and endwall

How to Link – See USDA BAER Catalog page 128 (PDF page 136).

What – A debris rack is a structure placed across a stream channel to collect debris before it reaches a culvert entrance.  A debris deflector is a structure (usually V-shaped with apex pointed upstream) placed at the culvert inlet to route the major portion of debris away from the culvert entrance.

Purpose – Designed to protect culverts from catastrophic failure by catching floatable debris that otherwise would likely plug culverts and cause stream diversion.  By protecting culverts from failing, these structures protect transportation infrastructure, public safety, and downstream resource values.

Effectiveness – No quantitative data exists on the effectiveness of debris structures.  However, anecdotal information indicates they can be effective with proper implementation and maintenance.  Problems can occur if the design structure is too small for the stormflows and associated debris.

Where

• Culverts at risk of plugging with debris.
• Where downstream infrastructure, public safety, or other resources are at risk.

Cost – $100–4000 depending on material.  Log racks built with onsite burned logs are economically efficient.  Structures constructed with heavy rail or steel range from $3000 to $30,000 or more depending on the size and materials required.  Additional factors include:

• Site location and access
• Materials required for implementation
• Number of structures

How to Link – See USDA BAER Catalog page 134 (PDF page 142).

What – Riser pipes function to sieve debris and allow passage of water.  Riser pipe allows accumulation of bedload sediments released from a drainage due to the loss of soil cover and reduced infiltration from water repellant soils.  The sediment and ash captured in the basin can be removed with a backhoe.

Purpose – Risers are used to protect road infrastructure, especially those with large fill, from failure.  Riser pipes help prevent culverts from plugging with sediment and floating debris.  Pipes capture sediment and reduce downstream impacts to water quality.  Riser pipes also reduce peak flows by storing water and sediment.

Effectiveness – No formal effectiveness monitoring data exists for risers.  However, reports indicate risers performed well when maintained.  Problems occurred when structures were not routinely checked and debris was not removed from the basin.  Risers are temporary treatments that are easily disassembled when no longer needed.  Risers are installed quickly and at a low cost.

Where

• Access at road crossings with a culvert inlet is limited by conventional equipment (backhoe).
• Drainages with high-burn severity and erosion predictions indicate a high risk of sediment delivery.
• Channels that have high bedload transport capabilities.

Cost – $750–1400 for labor and material.  Additional factors include:

• Location and access
• Culvert size and inlet condition

How to Link – See USDA BAER Catalog page 140 (PDF 148).

What – Mechanical equipment is used to clean out organic debris and sediment deposits in stream channels, above culverts, and in catchment basins ahead of anticipated runoff events.

Purpose – To prevent organic debris and sediment deposits from becoming mobilized in debris flows and flood events.  Intended to protect transportation and facility infrastructure. 

Effectiveness – No quantitative effectiveness monitoring data is available on catchment basin cleanout.  However, anecdotal information suggested the treatment is effective.

Where

• Locations where cleanout can be done prior to the first damaging rain.
• Road crossings where existing sediment reduces culvert capacity.
• Areas with high values-at-risk.

Cost – $200–2000 for each basin.  Additional factors include:

• Amount of material that is removed
• Location and access

How to Link – See USDA BAER Catalog page 145 (PDF page 153).

What – On-the-ground inspection and clean out, if necessary, of critical infrastructure during, after, or between precipitation events that may result in loss of water control. 

Purpose – Intended to keep culverts and drainage structures functioning on roads where access is required by cleaning sediment and debris from the inlet.  The treatment is used in lieu of more costly upgrades that are not feasible due to expense or time frame.  Storm inspection and response performed during runoff events should be conducted with caution.

Effectiveness – No formal effectiveness monitoring data exists on storm inspection and response.  Informal observations indicate cost effectiveness because some road problems are avoided with timely clearing and cleaning of road crossings.  However, challenges include maintaining a dedicated inspection team over time, and where excessive areas to patrol result in inadequate coverage.

Where

• Road crossings where high sediment and debris is anticipated.
• Road access is necessary throughout the storm season.
• Roads susceptible to landslides.

Cost – Equipment rates per day: backhoe $390; front-end loader $465; four-person crew $970.  Additional factors include:

• Location and access

How to Link – See USDA BAER Catalog page 150 (PDF page 158).

What – Trail stabilization methods include rubber belt and rock waterbars, rock spillways, and rolling dips.

Purpose – Designed to provide drainage and stability to reduce trail damage and erosion.

Effectiveness – No quantitative data exists on the effectiveness of this treatment.

Where

• On trails lacking adequate drainage features for anticipated runoff.
• Trails within or below high-burn severity areas.
• Trails with sustained grade through burned areas that lack adequate drainage.
• Trail segments that have the potential to deliver sediment to streams.
• Trails where previous drainage structures were damaged by the fire.

Cost – $1000–3000 per mile.  Additional factors include:

• Number of structures required within the treatment area
• Availability of material

How to Link – See USDA BAER Catalog page 153 (PDF page 161).

What – Mechanical equipment such as an excavator or dozer is used to decommission unauthorized roads that are destabilized as a result of loss of vegetation following high burn severity. 

Purpose – Intended to improve infiltration, restore hillslope hydrology, and reduce erosion following subsoiling (tilling), recontouring road fill, and restoring drainage through the road prism using mechanical equipment.

Effectiveness – No quantitative data is available on soil erosion rates.  However, visual inspection revealed that treatment objectives to improve infiltration and reduce erosion by restoring the slope were achieved in treated areas.

Where

• Hillslope with multiple unclassified roads.
• Areas with high-burn severity and high soil erosion potential.

Cost – $7000–8000 per mile.  Additional factors include:

• Location and access
• Equipment type and size necessary to implement the treatment

How to Link – See USDA BAER Catalog page 160 (PDF page 168).