Mudflow risk grows with valley population

ROB TUCKER; The Tacoma News Tribune

Puyallup, WA - 6/19/04 - Puyallup Valley cities and Pierce County continue to plan for a disastrous Mount Rainier mudflow, but relentless population growth could hamper their response if they ever have to put their plans into action.

The valley floor lies squarely in the historic pathway of lahars - what one expert described as rapidly moving flows up to 30 feet high and packing the destructive force of flowing concrete. Scientists say another lahar, traveling 60 miles and growing larger as it gathers debris, could strike tomorrow - or hundreds of years from now.

Whenever it happens, it will inundate a much more heavily populated area than when the last lahar hit 500 years ago. More than 59,000 people live today on the valley floor in cities and unincorporated areas, according to rough population estimates compiled by the Puget Sound Regional Council. Since 2000, nearly 3,000 people have moved there.

And there's no end in sight. All four valley cities are planning to take even more residents, guided by state growth management laws that say cities, not rural areas, should absorb population increases.

Faced with these growth pressures, none of the main cities standing in the way of a potential lahar - Orting, Sumner, Puyallup and Fife - has restricted the density of single-family homes on the valley floor. And only one of the four, Sumner, has capped the occupancy size of large new buildings from which people would have to escape.

One of Orting's former mayors says the lack of building regulations is evidence that the lahar threat isn't as bad as alarmists suggest.

"Why are we allowing people to build houses in the valley?" said Wayne Harman, who led the city in the 1970s and 1980s. "Maybe (governments) are not that concerned."

Pierce County does limit housing density and building occupancy in its part of the lahar zone. But the County Council next month might consider easing some of these restrictions, which would allow the fast-growing Orting School District and other agencies more latitude on where to build.

Local governments are uneven in their preparedness for lahars. But they are still considered pioneers on the international stage, said Kevin Scott, a scientist with the U.S. Geological Survey.

Scott, who works at the Cascades Volcano Observatory in Vancouver, Wash., said Pierce County governments took preventive measures far ahead of other places located near active volcanos.

"We use them as the poster child worldwide," Scott said.

But he allows for the possibility that local officials aren't doing exactly the right kind of lahar planning. In an article he wrote for a conference in January, he suggested forming a national advisory panel to assess Mount Rainier lahar risks. The experts' panel could justify local preparations or recommend that some be discontinued because of cost or ineffectiveness.

Here's a look at what local governments are doing:


This Puyallup Valley city is most at risk because it is entirely contained inside the lahar pathway and would be the first city hit by a mudflow from the glaciers on the west side of Mount Rainier.

Orting has doubled its population since 1990, with another 1,183 home lots proposed or approved for construction. It has no lahar-related building restrictions.

The city distributes lahar evacuation and related information to new residents. It is developing a pre-disaster mitigation plan, just as Pierce County and other cities are, said City Administrator Mark Bethune.

Orting officials are identifying, analyzing for risk and ranking the probability of different types of disasters. Then the city will determine how to help people in each scenario. State and federal authorities will review and coordinate.

"We're all trying to get on the same page," Bethune said. "And we're getting there. There aren't many places that are really safe. Seattle's on a big (earthquake) fault."


Sumner is the only one of the threatened cities that restricts building in the lahar area, which includes the entire city. No new building that holds 5,000 or more people can be built, said senior planner Ryan Windish.

Sumner is also one of the slower-growing places in East Pierce County right now. Fewer than 300 proposed home lots and apartment units are proposed in the city, Windish said.


Puyallup has no restrictions on building in the lahar pathway, but planners will discuss limits on building occupancy and land use later this summer, said Steve Pilcher, Puyallup city planning manager.

To avoid being arbitrary, they also want to factor in the proximity of large buildings to high ground. For instance, the Puyallup Fair handles tens of thousands of people each day during its 17-day run, but the grounds are at the base of South Hill where large crowds presumably could evacuate quickly and safely.

About 1,730 housing units are proposed for construction on the valley floor in Puyallup. Pilcher said proposals include an 80-home housing development and a 450-unit apartment complex, both on East Main Avenue, and a 1,200-unit senior housing project along West Stewart

SIDEBAR: Living in danger

People continue moving into the four cities in the Puyallup Valley that stand in the way of a lahar, a potential volcanic mudflow. Fife, Orting and Sumner are entirely contained inside the lahar zone, but much of Puyallup's growth is happening on South Hill, out of harm's way. Puyallup has no breakdown on population growth on the valley floor versus growth on South Hill.

City 1990 pop. 2000 pop. 2003 pop.*

Puyallup 23,875 33,011 35,490

Sumner 6,281 8,504 8,780

Fife 3,864 4,784 4,905

Orting 2,106 3,760 4,295

*State estimates

Note: Comparative population numbers for unincorporated areas on the valley floor aren't available.)

SOURCES: U.S. Census Bureau, State of Washington



Fife also has no restrictions on building in the lahar area, which encompasses the entire city. Fife officials ensure that all proposed subdivisions have streets built in a pattern that allows orderly evacuation, said Steve Worthington, community development director.

The industrial city behind the Port of Tacoma has increased its population 169 percent since 1980. As more farmland is plowed under and sewer service expands, the number of residents will only snowball. The city has 2,100 new home lots or housing units proposed for construction.

And full-time residents are only part of the equation.

"We have 15,000 employees in Fife during the working day," Worthington said.


The Tacoma Tideflats part of the city resides inside the lahar pathway. It's a heavy industrial area that also encompasses the Port of Tacoma, one of the largest ports in the United States.

Thousands of people work on the Tideflats during the day. The Tacoma Fire Department has established a way to notify businesses with an automatic telephone dialing system and recorded messages.

Meanwhile, the Fire Department is talking to the port about designating Tideflats evacuation routes because the port changes street patterns occasionally to install or modify large container facilities, said assistant chief Jeff Jensen.

Pierce County

County officials approved building restrictions in ancient lahar inundation areas 13 years ago. The rules apply to unincorporated parts of the Puyallup, Carbon, White and Nisqually river valleys.

When the county adopted its new comprehensive land-use plan in the mid-1990s, officials zoned much of the valley floor to allow only one home per 5 acres in mudflow areas, said county planner Katherine Brooks.

The county also capped the occupancy of bigger buildings in these areas. But now the County Council might modify those restrictions.

Currently, a school with a capacity of more than 250 people can't be built in a lahar area. Nor can any jail, medical facility with 50 or more incapacitated residents or any structure holding more than 5,000 people, according to the 1991 county ordinance on volcanic hazard areas.

But the county planning commission has proposed allowing larger buildings and covered assembly areas, as long as it's demonstrated that occupants have time to walk to safety before the projected arrival of a lahar.

Large developments close to Mount Rainier would face more restrictions than they do now: A building that's within 30 minutes of a lahar's point of origin could house only up to 100 people.

But developers of big buildings farther from the mountain would have more leeway: an allowed capacity of 500 to 5,000 people, depending on their distance from the lahar source.

The Orting School District illustrates the argument for this increased flexibility. It wanted to build a middle school in the unincorporated area south of the city but was blocked by the county's rules.

A school there would lie in the lahar zone and thus automatically violate county regulations, despite being next to a hill with a road that students could use to escape.

The district also explored buying land on high ground in the unincorporated area but couldn't find anything suitable for a school, said Superintendent Jeff Davis.

So instead it bought 100 acres inside Orting - even though it lies directly in the path of a lahar - because the city allows unfettered school construction. The land will stay vacant for now because of last month's school bond failure.

Until the rules change, Orting school officials have little choice but to make imperfect decisions about school locations.

"We have to react to growth," Davis said.

(Editor's Note: This is the second of two parts. Go to Part One.)

Staff writer Eijiro Kawada contributed to this report.
Rob Tucker: 253-597-8374

Part 2. Go to Part 1.



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