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Removing, transporting, and disposing volcanic ash is a dirty, time-consuming, and costly challenge. Coordinated action by the public and by organizations can significantly lower costs and speed up the time it takes to remove most of the ash. The fall of a few millimeters of ash on an urban community will likely result in the need for collection and disposal of large quantities of material. Proper disposal sites are needed quickly so that the (1) ash does not have to be moved a second or third time; and (2) cleanup operations can begin immediately.
The time and effort required to remove and dispose ash depends on the depth and aerial extent of the deposits, especially in urban and populated areas, and the availability of machinery (for example, from areas outside the zone of ash fall) to clean it up. Cleanup operations can take weeks to months to complete.
Several uncontrollable factors can speed up or delay the time required to remove the ash and frustrate the efforts of cleanup personnel:
Removal issues || Disposal sites || Coordination || Personal-protection equipment || Servicing machinery || |
Ash removed from roads, buildings, and other structures should be disposed of in a place and manner that (1) does not create a new hazard to the public or adjacent landowners; (2) does not allow wind or water to redistribute the ash; and (3) the ash does not have to be moved again. It may be advisable to request that people separate volcanic ash from normal garbage for collection or disposal at a designated location—mixing ash with normal garbage can result in damage to collection vehicles and take up space in landfills.
Several disposal locations may be necessary in order to provide sufficient capacity for all the ash. Choosing quickly one or more disposal sites after an ash fall is often difficult. Ideally, potential disposal sites are identified before a volcanic eruption on a regional basis as part of a contingency-planning process. An appropriate siting process can be developed to identify potential sites for use by all organizations and public agencies involved in clean-up operations. This might include a request for landowners to volunteer parts of their property for ash disposal, if necessary. Responsibility for operating one or more disposal sites needs to be assigned to an appropriate organization or public agency (Johnston and Becker, 2001).
Ash is generally regarded as good fill material, as it mixes well with soil, has good bearing strength for structural support, and supports vegetation growth if fertilized.
Desirable features of disposal sites (modified from Johnston and Becker, 2001):
- Site is close to ash cleanup area(s).
- Access exists for heavy vehicles from a main road.
- Situated away from waterways (which could be affected by any leaching or chemicals from the ash or fine material washed from the ash).
- Availability of soil for cover (although other forms of ground cover, including planting of rye grass, ivy, or use of pre-grown lawn/turf for immediate coverage, may be options).
- End use of disposal site is compatible with ash deposits.
- Meets local, regional, or national land-use requirements or laws.
Possible disposal sites (FEMA, 1984):
- Depressions on government-owned property.
- Unused rights-of-way (which can benefit or remain undamaged from the increased grade level of the fill).
- Abandoned rock quarries.
- Old borrow sites.
- Low or hollow areas on private property where the owner is willing to accept full responsibility for stabilizing the ash (it is reasonable to expect private property owners to accept the material free of charge).
- Farmland adjoining the rights-of-way (if acceptable to the farmers) where it can be incorporated into the cultivated land with no harmful effects; farmland in Eastern Washington on which ash from the 1980 eruption of Mount St. Helens was spread from adjacent roadways produced as much grain as sections of farmland without the ash.
- Household gardens and lawns, if ash fall is light.
To prevent wind from stirring up ash from a disposal site, strategies include the following (FEMA, 1984):
- Cover volcanic ash at disposal sites with a layer of heavy material such as soil or gravel.
- Fertilize and seed the disposal site to start vegetation growing.
- Use straw and other mulching materials to cover the ash.
- See potential use of chemical dust suppressents based on experience from the 1980 eruption of Mount St. Helens.
Public organizations and private companies in a metropolitan center or rural area are not likely to have sufficient equipment and employees to implement a widespread clean-up operation after a significant ash fall. Prompt requests for assistance and support from public and private sources located outside the zone can significantly help clean-up activities, especially if such requests are a part of existing regional contingency plans. Coordinating the use of both local and regional resources is critical to (1) prioritize actual clean-up operations of specific facilities, infrastructure, and neighborhoods in concert with businesses and residents; (2) make certain that resources are used most effectively; and (3) prevent cleanup activities from adversely affecting adjacent areas, infrastructure, or economic activities as much as possible.
In some cases, it may be helpful to restrict access to certain areas during clean-up operations. For example, a city-wide neighborhood clean-up program on a block by block basis using local and outside work crews and equipment proved extremely important in Eastern Washington after the 1980 eruption of Mount St. Helens. In the city of Yakima, access was restricted to sixteen blocks of the Central Business District for several days to minimize traffic problems (Blong, 1984).
If local fire-fighting equipment is used to help in cleanup activities, see recommendations to protect the fire-fighting capability and equipment.
Workers and volunteers involved in clean-up operations are typically exposed to high concentrations of airborne ash particles, and they should be supplied with appropriate personal protection equipment to reduce the potential for adverse health effects. Such equipment can include eye protection, filter masks, respirators, overalls, hats or helmets, gloves, and extra lighting. It might also be necessary to take extra care of people helping to clean-up the ash, including the supply of food, water, toilets, and temporary lodging for workers, many of whom may work in 12-hour shifts. See recommendations for cleaning up: outside.
Frequent servicing of machinery
All plant and machinery used in clean-up activities will likely need to be serviced on a more frequent schedule to lower the wearing effects of abrasive ash particles. For example, cleaning and lubrication, and changes in oil, oil filter, and air filter. (See description of vehicle damage and maintenance.) In addition, equipment that is not being used in clean-up operations should be sealed or covered in order to prevent ash from infiltrating the equipment.
During ash cleanup activities after the 1980 eruption of Mount St. Helens, local fire departments loaned hoses to volunteers, public works employees, and others unfamiliar with the proper use and care of the equipment. In the process, many departments lost many needed hoses, especially the lighter, single-jacketed hoses, and hoses were returned damaged after they were unnecessarily dragged over the ground. Because of this mishandling, the fire-fighting capability was lost and the replacement of equipment significantly added to the cost of cleanup. To prevent this, the following recommendations are offered (FEMA, 1984):
- Make certain fire fighters are present to ensure the proper protection of hoses and hydrants.
- Avoid distribution of fire hoses to citizen groups and other non-fire employees unless they are supervised and instructed in their use and the use of hydrants.
- Use only hoses designed for outdoor use.
- Do not drag hoses over pavement any more than is absolutely necessary.
Clean-up strategies || Mount St. Helens || Recommendations || |
Each community or public agency organizes an ash clean-up operation in its own way using the available machinery and equipment and, sometimes, the help of people and organizations not affected by the ash fall. The experiences of people who had to remove and dispose volcanic ash can help others avoid some of the hardships and mistakes they encountered. No one technique is likely to be the best in all situations and a range of measures often provides the best results. Constant monitoring of ash effects and mitigation procedures is encouraged to achieve the most effective balance between operational requirements and damage limitation.
Mount St. Helens, 18 May 1980; Yakima, Washington
Lessons learned (from Joe Jackson, City of Yakima, in Johnston and Becker, 2001)
- Don't panic or rush into the clean-up operation without thinking it through.
- Have a good arrangement with contractors prior to a disaster so you know you can count on them when they are needed.
- Develop a plan for the systematic clean-up of the city so those involved know what they have to do. Pre-planning can save a community a lot of problems.
- The finer the ash the more problems you will have.
- Keep good records, especially all financial documentation. A special emergency cost accounting system for audit verification of all ash clean-up expenses is recommended.
- Maintain daily briefings with the press/media to inform the public, establish trust and their cooperation in informing citizens. Involve all emergency agencies in joint announcement briefings.
Mount St. Helens, 18 May 1980; Spokane, Washington
Sawdust to bind fine ash for street-sweeping (from Scott Egger, Directory of the Street Department, City of Spokane)
- In 1980 when Mt. St Helens erupted, Spokane had over 850 miles of paved arterials and residential streets that required ash removal.
- The ash that fell in Spokane was so fine that it could not be picked-up with conventional equipment.
- Much of the fine-ash went airborne when it came in contact with conventional graders and street sweepers.
- Cities and towns located closer to Mt. St Helens were able to use graders and sweepers because the material was not as fine as the ash that fell in Spokane.
- Just placing water on the ash did not help. The City experimented with different material to find a binder that could be placed on the streets that would bind to the ash and make it easier and more efficient to pick-up.
- The Street Crews found that damp sawdust served as a good binder. Crews applied damp sawdust on City streets with sanders. The damp sawdust and ash were then swept-up with conventional Street Sweepers.
Recommendations for the removal of ash (links to other sections of this Web site):
Federal Emergency Management Agency (FEMA), Region X, 1984, The mitigation of ashfall damage to public facilities: lessons learned from the 1980 eruption of Mount St. Helens, Washington: [Seattle, Wash.], FEMA, 70 p.
Johnston, D. and Becker, J., 2001, Volcanic ash review - part 1, impacts on lifelines services and collection/disposal sites: Auckland Regional Council Technical Publication No. 144, 50 p.
Lauer, S.E., 1995, Pumice and ash, an account of the 1994 Rabaul volcanic eruptions: CPD Resources, Australia, 80 p.
Zais, R., 1999, City of Yakima: Presentation on the eruption of Mount St. Helens to Regional Council Civil Defense in New Plymouth, New Zealand.
