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May 18, 1980: The Day the Sky Fell
Managing the Mt. St. Helens Volcanic Ashfall on Yakima, Washington, U.S.A.

Presented at Cities on Volcanoes 2 Conference, Auckland, New Zealand

By Dick Zais, Yakima City Manager
February 14, 2001

Yakima Profile
The Eruption of Mount St. Helens
The Mountain Explodes
Ash Falls on Yakima
Community Clean-up
The Clean-up Process
Ash Fall Impact on Wastewater Treatment Plant
Volcanic Ash Aftermath
The Financial Impact of the Disaster


Thank you very much for inviting me to Auckland. It is a privilege and honor to be here as a United States citizen and a representative of the City of Yakima. I last visited New Zealand and the City of New Plymouth in March 1999, and am grateful for the opportunity to be here again in this beautiful country.

Last year I met Dr David Johnston of the Wairakei Research Center for the Institute of Geological and Nuclear Sciences. He was visiting Yakima during the 20th Anniversary of the eruption of Mount St. Helens and ash fall on our community. He invited me to attend this conference and share my experience of the eruption's impact on Yakima, since I was also City Manager at that time.

Yakima Profile

Yakima was incorporated in 1886. The City is located in the center of the State of Washington, approximately 200 kilometers southeast of Seattle, and approximately 110 kilometers east of Mount St. Helens. Our City population today is 70,000.

The Yakima Valley has an international reputation as a leading agricultural center. We are known as "The Fruit Bowl of the Nation" with major production of fruits such as apples, cherries, pears and wine grapes, as well as many dairy products. The total agricultural production of the Yakima basin is nearly $2 billion annually.

The City has a Council/Manager form of government. The City Council includes seven members.

I have served the City of Yakima for 27 years, and was appointed City Manager in January of 1979. We are a full-service city with 650 full-time employees and major City departments, including: Police, Fire, Public Works and Utilities, Community/Economic Development, Finance, and City Administration. Yakima's 2001 total budget is approximately $108 million.

The Eruption of Mount St. Helens

Mount St. Helens is in the center of the Cascade Mountain Range between the States of Oregon and Washington. Prior to its eruption in 1980, Mount St. Helenss was dormant and a picture of snow-capped beauty. However, geologists believe that Mount St. Helens probably has had catastrophic eruptions like that of Mt Vesuvius in 79 AD. There are traces of ash fall from previous eruptions that have been found from testing in Eastern Montana and southern Alberta, Canada, as well as the ash deposits that helped form the rich soil of Eastern Washington. The volcano's last documented eruption occurred in 1856.

In 1978 the U.S. Geological Survey published a report describing in detail the potential impacts from future eruptions and ash fall of the Mount St. Helens volcano. The report predicted that an eruption was likely to occur before the end of the century, and that prevailing winds would likely spread ash inland to areas east of the volcano.

Mount St. Helens volcano reawakened on March 20, 1980, when a seismograph at the University of Washington in Seattle recorded a minor earthquake centered 32 kilometres north of the mountain. On March 27, one week after the first earthquake, the volcano spouted a plume of ash and steam four miles into the air. By late afternoon, the mountain's snow-capped summit had a blemish; a soot-black crater estimated to be 76 meters wide and 18 meters deep.

Over the next several weeks a great deal of interest became focused on Mount St. Helens' volcanic activity and its venting of ash and steam. The U.S. Geological Survey moved in a team of scientists to set up a base for monitoring and evaluating the volcano's re-emergence. The initial public response was one of fascination and sightseeing as the area surrounding the mountain became congested with planes and vehicles carrying scientists, news media journalists, and tourists.

Throughout April and early May, ash and steam eruptions continued on the mountain, and an ominous bulge formed about 2,400 meters up the north face of the mountain. The area had expanded about 92 meters and was continuing to grow. Experts speculated it was caused by the pressure of molten rock moving up within the volcano, but a major eruption did not seem probable.

In Eastern Washington, our citizens were interested in the volcano's re-emergence, but mostly we were oblivious to any threats from the mountain. On May 18, 1980, our lives would change forever.

The Mountain Explodes

On Sunday, May 18, 1980, at 8.32 a.m., a strong earthquake of 5.1 on the Richter Scale was registered at Mount St. Helens. The northern face of the mountain began to collapse; jarred loose by the earthquakes, it slipped down the mountain's sides. A plume of steam shot from the summit and the north side of the mountain, and within seconds the cloud turned black, pouring into the sky. The rock and ice build-up in the mountain that had been holding back pressure from the pent-up gasses and magna in the core of the mountain exploded. Hot gas and ash, and huge chunks of rock and ice, catapulted from the weakened north face of the volcano. The black plume, laced with pink and purple sheets of lightening, shot 18 kilometers into the air in a pyrotechnic display that lasted the entire day.

The blast was 500 times greater than the 20-kiloton atomic bomb that fell on Hiroshima, and it washed over the foothills and valleys beneath the mountain. In moments, it covered 388 square kilometres, levelling all that stood in its way. More than a cubic mile of material - over a metric ton of debris for every person on earth - was expelled from the mountain and pulverised into the stratosphere. Huge mudflows and timber travelled down the mountain to the Toutle, Cowlitz and Columbia Rivers below, causing catastrophic flooding and damage to property and destroying over 300 homes. Millions of 200 year-old fir trees were flattened and strewn like match sticks with their bark scarred and branches stripped.

Carried by the eastern prevailing winds, Mount St. Helens ash and smoke billowed to the northeast, across the skies, towards a half a million people in Washington, Idaho, and Montana.

The impact of the blast was enormous. It literally tore the top of the 2,959-meter peak apart. Its blackened crater was now 1.4 kilometers wide and 2.5 kilometers long, and the mountain was nearly 900 meters lower than it had been seconds before the eruption. In the wake of Mount St. Helens an estimated 70 people perished, although the exact number of victims buried under mud and ash may never be known for certain.

Ash falls on Yakima

Yakima had no forewarning about the eruption. I was at home on Sunday, May 18th, when the sky turned dark by mid - morning, and I expected a major thunderstorm.
It was only when the ash began to fall that I realized the volcano had erupted, and that we could be facing a serious emergency. By noon, the City was engulfed in darkness and communications by home telephone were impossible. It was like an eclipse of the sun that lingered-a blinding blizzard and a thundering electrical storm all in one. Street lights came on automatically, traffic stopped, and a strange quiet fell on our community; everywhere a talcum-like, sandy, gray powder kept accumulating. Cars, trucks, buses, and trains all stoped, and planes were re-routed away from the ash cloud.

From noon until 6.00 a.m. the following morning, the City was in total darkness. The ash fall on the City was gritty and light and difficult to sweep or shovel, especially when dry. Shifting winds blew the dust everywhere, severely impairing visibility and driving in our area. It was exceedingly harmful and abrasive to mechanical and electrical equipment, especially the motors of vehicles, aircraft and electronic systems.

The ash fallout was especially crippling - Yakima received nearly 3 inches of this material in the first 24 hours following the explosion. We estimated that several million tons of ash was deposited on the entire region. Initially, most citizens were caught unaware and were confused about what effects or risks the ash fall could present to themselves and their property. It appeared serene and many thought it would be washed away with the next rainstorm.

I left for my office at about 12:30 p.m. on May 18th to be in close communication with the emergency services of the City and begin the process of co-ordinating and directing our emergency response effort.

While the City did have an Emergency Operations Plan, there was no past experience in dealing with a volcanic eruption and ash fall. The first 48 hours were a critical time for the City, during which we organized ourselves into a command post at City Hall and worked to prepare a strategy and plan for responding to the emergency.

The command center included the Mayor; City Manager; County Health Officer; County Emergency services Director; Police and Fire Chiefs and community leaders. Our most immediate actions included the following:

  1. An immediate disaster was declared by the City Council to alert the public, through all the media, that the City's emergency services and facilities were in full operation; the public was urged to remain calm and stay at home. Immediate aid was also requested from the federal and state governments.
  2. A central communications center was established at City Hall to inform the media and public about emergency operations. All public announcements from the City were coordinated and issued in a daily press conference which included the Mayor, County Health Officer, Police and Fire Chiefs, the Director of Emergency Services, the City Manager, and representatives from the County Public Safety Services.
  3. The health department initially advised that inhaling of the ash may be harmful to human health, and people were urged to use surgical masks to protect themselves outdoors. (The 3M Company diverted its entire supply of one million masks to Washington State for distribution to anyone in need).
  4. Police and Fire Departments were placed on full alert with all personnel called to duty. City emergency response vehicles and police patrol units were outfitted with special "filters" (including pantyhose!) to protect engines from intake of the airborne ash.
  5. The City's Municipal Airport was closed indefinitely, since the ash posed a major threat to the mechanical systems for aircraft and ground support equipment.
  6. The City instituted 24-hour continuous monitoring of the City's domestic water treatment plants to ensure that no contamination occurred in the City's potable water supply.
  7. The entire Central Business District was ordered to close business operations indefinitely to enable the clean-up effort to begin.
  8. All schools and classrooms were closed and City transit and refuse collection services were suspended.
  9. Motorists were asked to remain off the roads as much as possible because of a nearly complete lack of visibility and extreme hazardous driving conditions.
  10. Emergency shelters were designated for stranded people, including visitors, business people and tourists.
  11. The Military National Guard was activated by the Governor to help provide security, support and clean-up assistance.

Community Clean-Up

We immediately recognized that our local government resources were completely inadequate to address the clean-up requirements facing the City. I contacted the City of Seattle, King Country government in Seattle, the City of Portland, and Multnomah County government in Oregon to request the special equipment and manpower needed for ash removal from our community. The major equipment acquired included the following:

Help from these agencies arrived in two days and the equipment was stationed at the City's Public Works maintenance yard. The amount of equipment and manpower engaged to assist the City of Yakima for the ash fall clean up was 10 times greater than our normal maintenance effort.

In planning for the emergency clean-up campaign, the City was divided into a grid pattern, starting from the Central Business District and extending to outlying suburban and residential areas. Assignments were made for manpower work crews and equipment for each location, and a daily schedule for the operation was published in the newspaper.

The second major part of the response was the coordination of a massive overall city neighbourhood clean-up with our community, citizens and business. Churches and other organisations also recruited volunteers to assist in the clean-up of private properties of the elderly or handicapped.

The Clean-Up Process

The plan for removal of the ash included the Central Business District, hospitals, fire stations, the Airport, streets/alleys, school areas, roof tops, hills, parking lots, and other residential locations. Eventually, the entire city was cleaned on a block-by-block basis, through the cooperation and coordination of neighbourhoods, residents and volunteers working with City crews and equipment.

The City learned by trial and error the best way to pick up and dispose of the ash on our community. The procedure involved the following:

  1. The ash on the streets and in the alleys was dampened by water and flush trucks. Residents were advised to also wet the ash down to prevent it from becoming air borne. Sawdust was also utilized to stabilize the ash from blowing winds.
  2. Neighbourhoods were then asked to shovel, sweep and stockpile ash in the City street at designated areas, 2 meters away from storm and sewer drains.
  3. Graders and loaders would follow, pushing and lifting the ash piles into large 12-yard dump trucks, which were then dispatched to 25 different landfill sites where the ash was deposited and covered with topsoil.
  4. The procedure was then followed by street sweepers which would clean the streets again, several times, to pick up the remaining ash deposits.
  5. Roof cleaning ranked equally to street cleaning in the overall as clean-up effort. The roofs had to be cleaned before ash was picked up from the streets and alleys. A combination of methods were used for the roofs:
  6. Large, truck-mounted vacuum units were employed for major flat-top buildings which could extract ash from the roofs into a tank which contained it from further release into the air.
  7. Ash was swept off the roof of each building into the alleys and streets and washed down prior to the clean-up crews coming into that area.

The City removed over 544,000 metric tons of ash from our community, which were deposited in community landfill sites! The airport alone removed over 15,000 metric tons of ash. The in-field horse track at the Yakima Fairgrounds was covered with over 136,000 metric tons of ash. Also at a City park, ash was dumped to a depth of 3 meters, with over 317,000 metric tons of ash. An irrigation system was installed, and rye grass was planted which grew quickly in the ash. Eventually, a new City park and soccer field complex was created from an area that had previously been a low wasteland. Ash was also used as fill material in a number of other privately-owned locations throughout the Country.

Clean-up of the entire City took only 7 days of 24-hour clean-up activities involving the crews from the City and other governmental agencies, private contractors, and volunteers.

Ash Fall Impact on Wastewater Treatment Plant

In the early hours of the emergency response, one of the areas of key concern was the ash fall on the Wastewater Treatment Plant.

The day after the eruption, major equipment was beginning to suffer from effects of the ash. Sever vibrations were occurring in the grit classifiers; raw sludge lines were becoming plugged; and pumping difficulties were being experienced. As grit and ash passed through the system, the inability to pump raw sludge threatened secondary treatment processes. The ash was becoming toxic to the biological media in the plant; pre-treatment systems were failing and lagoon basins were becoming inundated with ash.

Faced with these extreme conditions, and to prevent losses in the tens of millions of dollars, City officials shut down the plant three days after the eruption. Raw sewage was discharged into the Yakima River, immediately east of the Wastewater Plant. At this time of the year in our community, there is high run-off in the Yakima River from the snow melt in the mountains, thereby substantially diluting the contaminating effects of the raw wastewater into the river.

Operating on a 24-hour schedule, City crews worked continuously to clean, inspect, flush and re-lubricate all of the equipment at the Plant and ash was also removed from the lagoon basins. After four days wastewater flows were re-directed back into the Plant on a phased primary treatment basis. Over the next three weeks, plant systems were gradually restored to enable the Plant to resume its normal operations.

Our experience with this situation changed our plans for future design of Wastewater Treatment Plant facilities, including the necessity to house all equipment under cover; specify dust-free motors, seals and air filters; cover the biofilters; and plan for a future cover on all clarifiers.

Volcanic Ash Aftermath

Mount St. Helens ash fall reached across the United States within 5 days following the eruption. Other communities east of Yakima in Washington, Idaho and Montana experienced similar problems as Yakima, but in gradually diminishing quantities the further east the ash cloud penetrated.

Yakima was fortunate that no loss of life was experienced, and that the ash content was not toxic to human or animal health. Nevertheless, the eruption of Mount St. Helens did have a catastrophic impact on the surrounding landscape. It created a powerful, dramatic and dynamic change in the physical geography and natural environment of the region which continues to the present day. In just a few moments, the mountain and region was transformed beyond anyone's imagination, and left an enduring image of devastation and desolation. Yet 20 years after the eruption of Mount St. Helens, the area, overall, has also begun to renew itself with new vegetation, plants and flowers growing from the new layer of volcanic soil.

The Financial Impact of the Disaster

While the City's first priority was to respond to the emergency, we were also worried about the cost impact to our community. The City prepared an extensive record and documentation of costs and expenditures on the clean-up and damages to help obtain federal and state reimbursement of disaster costs.

The total financial impact on the City from the emergency was $5.4 million for the City's clean-up and damage to the City's Wastewater Treatment Plant. Approximately 74% of this total was eventually paid by federal and state assistance and private insurance carriers. The City's cost was $1.4 million, or approximately 26%. The City financed this expense through general obligations bonds. It took many years to repay the entire indebtedness and recover the Federal reimbursement for our expenses incurred from the disaster.

In the first few weeks following the eruption, there were early news reports that the economic losses to our area, especially agriculture, could be hundreds of millions of dollars. The actual economic losses to our region were approximately $12 million. However, the final calculation of total economic cost of the eruption of Mount St. Helens on both public and private activities state-wide was approximately $1.5 billion.

In the weeks following our recovery clean-up from the St Helens ash fall on Yakima, the concerns about severe economic damages and losses to our area reported in the national news media prompted an aggressive campaign to advertise and report that our area had not been devastated. This effort was successful in boosting sales of our apple harvest and other agricultural commodities. Ultimately, Yakima did produce an excellent crop for domestic and international markets that year.


Prior to the Mount St. Helens disaster, emergency planning and preparedness assumed a very low profile among the large number of other local government problems requiring daily attention. However, the Mount St. Helens eruption and ash fall on the City has dramatically changed emergency preparedness for the future.

Our experience with the Mount St. Helens eruption and disaster illustrates that a City, in an emergency situation, must initially plan to be on its own and utilize all available local resources. However, it is also important to make plans for obtaining assistance from others, if possible, in the event that your own resources are inadequate to handle a disaster condition. The best approach is to have plans in place before an emergency ever occurs.

Daily information announcements and reports to the public on the status of emergency conditions and response efforts are essential, and should be closely coordinated and presented by City leaders, in cooperation with all sectors of the media.

Managing and coordinating the response to a major emergency is highly demanding and stressful on everyone, especially the person in charge. It is important to remember that an Emergency Manager is not indispensable, but is part of the team assembled to meet the challenge at hand. You must be willing to delegate quickly and trust others - you can't do it alone. Critical decisions are more successful if jointly planned and supported by the team working together.

The 10 days following the eruption and ash fall on Yakima were traumatic and hectic, but rewarding. It was traumatic to see our valley turned into a gray, swirling dust bowl; hectic to try and find answers and solutions to the unknown, but at the same time, rewarding in unifying the community to meet an incredible challenge. We are extremely proud of our City's response to this emergency. It was an outstanding demonstration of community spirit, dedication, teamwork and commitment to restore us to a healthy, clean and safe environment.

Today the Yakima Valley and the entire State of Washington remains a highly attractive area for new residents and economic opportunity. In the 20 years since the eruption, there has been a renewal in the physical growth and natural environment surrounding the volcano. In Yakima, we also have seen a significant expansion of agricultural production, and economic development and investment. We are optimistic about out future, but at the same time must respect the forces of nature, and be prepared for future potential eruptions from Mount St. Helens or other volcanoes.

I have had a very rewarding and challenging career in City management. Nevertheless, the eruption of Mount St. Helens was a milestone event and experience for me, personally and professionally, which I will never forget. I will be forever grateful for the opportunity to serve the City and help bring our community together to respond so positively and successfully to this emergency.

Thank you for the opportunity to share my experience with you today.

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