Most communities and organizations tackle the ash cleanup of roads and highways using their available road-cleaning equipment and, sometimes, with the help of those not affected by ashfall. If ash is pushed to the side of the road instead of removed, wind and vehicle movement will cause it to stir or billow, creating clouds of ash for weeks or months.

Ash typically is removed from urban areas even for accumulations of only a few millimeters. A number of factors will influence the removal method employed, the ease with which ash can be removed, and the cost of any clean-up operation. These include ash thickness, grain-size, availability of equipment, and the degree of cooperation and assistance from residents.

*All recommendations below are modified from U.S. Federal Emergency Management Association, 1984.

Removing ash from paved roads and urban streets

  • Provide direction to property owners along roads and streets to be cleaned to move ash from roofs and the rest of their property to the street. To avoid blockages, ash should be placed away from waste-water drains and gutter downspouts that enter the road to avoid blockages.
  • Coordinate the various road, residential, and building clean-up efforts to prevent the need for more than one ash-cleaning sweep in each area.
  • Before starting cleanup activities, build small dikes (for example, using sandbags filled with ash) around catch basin inlets and waste-water drains or sewer systems to prevent ash from entering the drains.
  • Encourage residents to organize into neighborhoods on a block by block basis in order to sweep and water down roofs and pile dampened ash in windrows on the street at the same time. Such windrows can reach one meter tall and a few meters wide. Coordinate street cleanup when neighborhood teams have completed their work.
  • Moisten the ash using a sprinkling system. Avoid getting the ash too moist because a wet ash slurry is difficult to isolate and collect.
  • Use motorized graders to scrape or blade ash to the middle of the road into berms or windrows. Collect, load, and transfer the ash to trucks, then haul the ash to approved disposal sites.
  • For a thorough cleaning of paved roads with storm sewers, after the ash is removed, use power brooms on the remaining dampened ash.
  • To remove the remaining ash on paved roads without storm sewers, flush the roads with water (see next section below).
  • As soon after the street cleanup as possible, remove ash deposits from catch basin inlets with vacuum trucks or machines with jet prodding and vacuum systems. Long delays in cleanup allows time for the ash to develop a surface crust or compact into pieces, making it harder to remove.

Removing ash from paved or oiled roads that have no curbs or sewers

  • Sprinkle ash with water and use motorized graders to blade it onto the shoulders or into the ditches. Collect, load, and transfer the ash to trucks to be hauled to dump sites. Remove the residue by sweeping or flushing the road with water, if necessary.
  • If gravel shoulders exist, replace lost gravel in order to maintain the integrity of the roadway.

Removing ash from gravel roads

  • Use motorized graders to blade the ash into roadside ditches, being careful to avoid unnecessary loss of surface materials (gravel).
  • If the existing right-of-way is wide enough, spread the ash along the back slopes outside the ditch. (Note that much of the ash may become integrated into roadside vegetation and that the ash in these areas will blow for some time during windstorms.
  • Remove ash blocking the drainage in ditches and culverts, and transport it to a disposal site.
  • A considerable amount of ash will remain on the roadbed surfacing, creating a serious visibility problem for traffic. Nothing can be reasonably done to eliminate it totally, but it will decrease with time.
  • On the roadbed, place a thin layer of rock consisting of graded material 5/8 inch or less and crushed to standard specification. This layer can be added and processed into the existing surface to achieve the binding effect that will stabilize the surface under traffic. (While this expensive method will not provide total dust control, it is, nevertheless, the most suitable method available for achieving visibility levels so that traffic operations can be restored.)

  • Notes
    Since roadway and visibility problems vary in each ash-affected area, no specific clean up information for ashfall thickness criteria for gravel roads can be provided. However, in determining thickness, the following factors should be considered:
    • Prevailing depth of ash deposit.
    • Functional classification of the road: its importance as a service road and acceptable speed restrictions.
    • Traffic characteristics: average daily traffic; variation in volumes; operation of intersections; turning conflicts.
    • Condition of existing surface undulations, washboards, and ruts affecting loss of material if ash is bladed to shoulders.
    • Existing surfacing material depth, quality and gradation as determinants for integrating the ash by scarification, mixing, blading and processing existing material.