Altered shoreline raises future risk

FLOODING: Sea level rise could inundate parts of downtown built on fill

October 24, 2010 

Capitol Lake tide

A view from Thurston County Courthouse hill reveals how downtown Olympia appears to be floating on the waters of lower Budd Inlet at high tide.

STEVE BLOOM — The Olympian

OLYMPIA - A sea wall to hold back the rising waters of Puget Sound could be the next major alteration in the long history of Olympia's changing downtown shoreline.

While city officials are in the very early stages of figuring out how high – and how expensive – a protective dike around downtown Olympia would have to be to reduce flood risk from sea level rise, it’s the latest chapter in a cautionary tale about what happens when people reshape their environment in the name of economic growth and development.

Decisions made dating back to the 1870s to dredge the shallow mudflats of Budd Inlet and use the dredge spoils to increase the land base downtown have had myriad consequences, both intended and unintended.

One unintended consequence: The area of downtown Olympia most vulnerable to flooding from sea level rise mirrors the area built on fill from dredging the bay.

“The old shoreline would become the new shoreline,” observed People for Puget Sound science director Doug Myers.

Fifteen dredge and fill projects added 434 acres and 1.9 miles of shoreline to downtown Olympia between 1893 and 2007, including most of the Port of Olympia peninsula, according to a 2008 study by the Thurston Regional Planning Council.

An additional 124 acres of the Deschutes River estuary – today’s Capitol Lake – a sliver of land along West Bay Drive and a marshy slough that today supports Plum Street and connecting streets also are man-made.

“Olympia was in competition with Seattle and Tacoma for economic development and industry, but it sat on the shallowest inlet in Puget Sound,” noted Tom Rainey, a South Sound historian and professor at The Evergreen State College. “The dredging and filling was an attempt to keep the state Capitol and develop the area as fast as possible.

“By the 1930s, Olympia was a smokestack community,” Rainey continued. “To think the Olympia shoreline could have stayed in its natural condition is unimaginable, given the economic ethic of the day. If it had, Olympia would be a sleepy little hollow today.”

GROWTH AND ITS LEGACY

The dredging and filling allowed the city to grow. The port peninsula and West Bay of Budd Inlet became home to industry and, in 1922, the Port of Olympia, which included a deepwater port.

Olympia’s new industrial shoreline hummed with plywood and shingle mills, veneer plants, lumber mills, oil and fuel storage depots, and the Cascade Pole wood preservative plant.

By the 1980s, the mills and pole-treating plant were gone. But they left behind a legacy of pollution that today’s public and private developers were left to clean up, including heavy metals, petroleum products and highly toxic dioxin.

That legacy is still having a major effect on downtown in 2010.

“One could argue that all the legacy pollution has stymied economic development in downtown Olympia, especially when it can cost $1 million or $2 million to clean up a site prior to construction.” Olympia-based engineering consultant Chris Cleveland noted.

Sometimes, the cost of the city’s industrial past is even greater: City of Olympia officials spent $7 million to clean up pollution at the new City Hall site on Fourth Avenue, city project engineer Rick Dougherty said.

Even so, the contaminated fill material may be better than the alternative, said Bob Wubbena, a retired Olympia engineering consultant.

“The downtown fill created a trap for the pollutants, but is that necessarily a bad thing?” Wubbena asked. “Otherwise, it would have been dispersed directly into Budd Inlet.”

EARTHQUAKE ISSUES

The fill area made downtown more vulnerable when major earthquakes struck in 1949, 1965 and 2001. In a strong earthquake, the sandy, loosely packed fill material is the first to lose strength and collapse, a process called liquefaction.

“It’s just plain really, really bad stuff,” state Department of Natural Resources geologist Tim Walsh said of the fill material. “They didn’t clean up before they started filling, so there’s lots of potential for settlement and liquefaction.”

In past earthquakes, evidence of liquefaction appeared on the port peninsula. Deschutes Parkway, which was built on loose, unconsolidated fill material, was torn apart by the 1965 and 2001 earthquakes. And much of the building damage in downtown Olympia during past earthquakes occurred in the fill areas.

In addition, pilings from old wharves and piers in lower Budd Inlet were left in place when they filled, creating potential projectiles in an earthquake, Walsh said.

Today, pilings for new construction in the fill areas of downtown rarely are embedded in native soils, relying for strength instead on the friction created by going down 100 feet or more to anchor the buildings. A case in point, the LOTT Clean Water Alliance’s new administration and education center on port peninsula fill sits on pilings that extend 95 feet to 120 feet deep, noted Karla Fowler, community relations and environmental policy director for LOTT.

SEA LEVEL RISE

Almost all of the area in downtown Olympia that is most vulnerable to sea level rise, which includes the north end of the port peninsula and the downtown area around Capitol Lake, is within the expanded — not the historic — Olympia shoreline. Most of downtown Olympia sits between 1 foot and 3 feet above high tide.

Studies by the University of Washington Climate Impacts Group and others predict that water levels in Puget Sound could rise anywhere from 6 inches to 50 inches over the next 100 years because of global warming. The midlevel projection for South Sound is 18 inches of sea level rise by 2050 and 2.9 feet by 2100.

Sea level rise is complicated in South Sound by two factors: It is the part of Puget Sound with the greatest tidal fluctuation, and the area most prone to subsidence, or sinking. Subsidence in the downtown fill area could be accelerating because of compaction, but that has not been verified, a September city staff report to the Olympia City Council noted.

Here’s why city planners recommended, and the City Council agreed unanimously in October, to spend about $75,000 next year on preliminary design and engineering of sea walls and other barriers to hold back the tides:

 • At 1 foot of sea level rise during extreme high tides, which occur a couple of times a year, water would pond on streets and flood low-lying structures.

 • At 2 feet, the water in stormwater pipes could flow in reverse, spilling into streets from storm drains during storms and high tides.

 • At 3 feet, extreme high tides could overflow many areas along the shoreline and flood most of downtown. Such an event could compromise the LOTT wastewater treatment plant on the port peninsula.

Armed with these scenarios, Olympia is thought to be one of the first cities in the United States to pursue a seawall strategy to combat climate change, Olympia Public Works Director Michael Mucha said.

“We’re already behind schedule,” former Olympia City Council member Karen Messmer said last January on a morning when a high tide almost flowed over lower Percival Landing. “We need to get serious about flooding from sea level rise.”

She said the decision to move the new City Hall from an East Bay site to its current location on Fourth Avenue, which city officials said raised the ground floor level by about 3 feet, was driven in part by the rising sea.

“Downtown Olympia wasn’t built with any data about sea level rise taken into account,” Myers noted. “But that’s the same story everywhere in Puget Sound.”

So is the pattern of altered habitat and natural system in the name of economic growth and development, Rainey noted.

“We have too many people chasing fewer and fewer natural resources,” he said. “We can’t afford the luxury of making the same mistakes our forefathers did.”

Future coverage: The decision to dam the Deschutes River and create Capitol Lake is a hot button topic 60 years later.

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