Officials keep nervous watch on levees
Analysis finds weak links in system to hold back major floods
The same railroad embankment that failed to stop the disastrous Vanport Flood of 1948 remains a weak link in Portlands levee system designed to prevent floods.
A new engineering assessment of the Columbia River levee system found four problem areas that dont meet stiffer federal flood-protection standards enacted after Hurricane Katrina. The biggest one is the railroad embankment used by Union Pacific and Burlington Northern Santa Fe trains as they chug north and south between Heron Lakes Golf Club and Smith Lake in North Portland.
For decades, the railroad embankment has performed double-duty as a north-south levee to hold back Columbia River flood waters. However, the embankment was constructed as a railroad, not as a levee, says Sara Morrissey, natural resource planning manager for Multnomah County Drainage District, which operates the levee system.
The U.S. Army Corps of Engineers rebuilt the railroad embankment after it failed in the Vanport Flood, says Reed Wagner, executive director of the Multnomah County Drainage District. But flood-control standards used by the Army Corps and Federal Emergency Management Agency have tightened considerably since Hurricane Katrina, Wagner says. What was considered safe as far as construction and design 10 years ago may not be now.
As part of a new federal recertification required for the Columbia River levee system, Cornforth Consultants led a team that analyzed the western portion of the levee system. Consultants concluded the railroad embankment doesnt meet the new Army Corps standards for protecting the region from a 1 percent flood, according to Mike Meyer of Cornforth, who presented the teams findings at a Sept. 26 public meeting at the Portland Yacht Club.
Theres a 1 percent chance such a flood will occur any given year; those formerly were called 100-year floods, to suggest they could come only once per century. Portland has experienced such floods more often in 1996, 1964, 1948 and 1894.
Geotechnical specialists doubt the rail embankment soil is compacted enough, and its believed to contain decaying old wood from a trestle once traversed by trains on the site, which doesnt meet federal standards.
Theres also a cherry tree with a three-foot diameter on the side of the embankment, Meyer says. If this tree was to topple in a storm event, you could lose half of your levee.
But such issues may be irrelevant. Union Pacific and Burlington Northern Santa Fe never allowed the consultants to adequately test the soil under the rail tracks, Morrissey says. Neither company wants to formally acknowledge the land under their rail line is a levee or agree to operate it as such, Morrissey says, and they have both said its against their national policy to do so.
Even if the companies allowed proper studies of the railroad embankment, it cant be used as a levee without an operating agreement with the two rail companies, she says.
Such operating agreements are a new requirement of the Federal Emergency Management Agency or FEMA, Wagner says.
Union Pacific Railroad opposes designating railroad rights of way as levees, says company spokesman Mark Davis.
Railroad embankments are not designed or constructed and are thus ill-suited to perform as levees, thus posing a significant and unacceptable safety risk to the public, Davis says. The use of railroad embankments on railroad rights of way as levees exposes Union Pacific to unquantifiable costs, liability and damages.
The drainage district has a tiny staff and budget, but a big mandate to prevent flooding from the Columbia River. Without the 18.5-mile Columbia River levee system, large parts of North and Northeast Portland would be deluged as much as eight months of the year.
The levee system protects $20 billion in property value, including Portland International Airport and the city of Portlands backup water supply.
So Gov. John Kitzhaber deemed the levee certification process a matter for Oregon Solutions, an agency he created that brings together public and private sector groups from across the state to focus on select issues. The Oregon Solutions team includes representatives from the city of Portland, Multnomah County, Metro, the drainage district, state of Oregon and other entities.
Oregon Solutions, now a part of Portland State University, will discuss how to proceed on the rail issue in November, says Steve Greenwood, deputy director of the National Policy Consensus Center, the parent organization of Oregon Solutions. The group applied to the Army Corps of Engineers for money to study alternatives, Greenwood says. One option is to build a setback levee, a smaller earthen berm next to the rail embankment.
Other problem areas
The other big problem identified by Cornforth is the Interstate 5 interchange with Marine Drive. Engineers determined that two parts of the cloverleaf interchange are too low by 6 inches to 2 feet, Morrissey says. Federal standards generally require levees to be high enough and strong enough to withstand a 1 percent flood. Construction of roads may take place on top of the levee if there is at least three feet of fill above the minimum levee height. But those two stretches of the freeway interchange fall within that three-foot fill zone by a matter of inches.
Engineers also determined that one corner of the levee near the Edgewater Country Club, just northwest of Marine Drive and Northeast 33rd Drive, also is too low by 6 to 12 inches. That shouldnt be a major issue because its on a vacant lot, Morrissey says.
The final problem area uncovered by engineers is the Peninsula Drainage Canal. The water level in the canal is too low by one inch, which engineers say can cause erosion and instability in the levee.
Solving that issue will be more challenging, because the area is home to the Western painted turtle and other sensitive species, Morrissey says.
But the assessment didnt look at the entire levee system. The eastern portion of the system, which includes Portland International Airport, still must be evaluated in a second phase, along with the levee system on Sauvie Island, Greenwood says.
And engineers didnt even consider seismic stability in the levee system, as thats not required by the Army Corps. Morrissey hopes it will get addressed later by the Oregon Solutions team.
In 1948, 18,500 residents, many of them African-American, remained in Vanport, a city hastily built in the Columbia River floodplain to house workers who flocked to Portland to work in wartime shipbuilding and aluminum industries. A railroad embankment on Vanports western flank served as the main bulwark against flooding.
On May 30, as the Columbia River neared its crest, Vanport lay 15 feet lower than the river, but the U.S. Army Corps of Engineers told residents they were safe.
Later that day, part of the embankment gave way, leveling much of Vanport and killing more than 50 people.