As global climates continue to shift, West Linn working to update stormwater plan
At first glance, West Linn's initiative to update its stormwater master plan — likely to begin this month — might appear to be reactionary.
It is, after all, coming on the heels of an unrelenting winter that saw a number of heavy snowstorms and persistent rainfall which caused flooding in a number of homes. But the timing is simply a coincidence, and Public Works Director Lance Calvert said that the city's current stormwater drainage system actually held up fairly well through the deluge of precipitation.
"Our topography in West Linn really accommodates a lot of stormwater," Calvert said. "So far this winter, we haven't had a lot of issues — some minor stuff this season with some blocked local inlets, and we've cleared those."
Yet the update to the stormwater master plan — which was last done in 2006 — will come amid increasingly uncertain times. Global temperatures have reached record highs for three years running, according to the National Oceanic and Atmospheric Administration, and scientists almost universally agree that these rising temperatures are contributing to climate change across the world.
Thus, as cities like West Linn update their infrastructure, it is with the knowledge that what was once considered a "100-year storm" — in other words, a storm with an intensity level that has a 1 percent chance of occurring — could one day turn into a 10-year storm with a much higher probability figure.
According to Calvert, however, there remains too much uncertainty around climate change for it to factor heavily in stormwater management planning. One particularly busy winter does not provide enough data to work with.
"It's not like the Portland metro area has not seen, in the past 100 years, a Pineapple Express scenario that dumped a lot of rain here — that's not necessarily an unusual event," Calvert said. "Now if it happens like this every year, and we have record snowfalls every year for several years in a row, maybe there's something. But if it bounces, how do you quantify that?"
The conundrum, of course, is that the hypothetical presence of that data would indicate a problem that is beyond fixing.
"The problem with climate change is if you do have the hard data, it means it's already too late," Calvert said. "The whole debate right now isn't about fixing climate change, it's more how do we prevent any potential damage from climate change. An 'ounce of prevention is worth a pound of cure' kind of mentality, and how you do that on a local basis."
West Linn Mayor and professional geologist Russ Axelrod agreed that there is "a lot of uncertainty about climate change" when it comes to West Linn's plans for the future, but added that there are still known areas of the city that need improvements when it comes to stormwater management.
"There are some areas of town where our stormwater system isn't ideal," Axelrod said. "It's managing the capacity it's designed for, but ... we might need to revisit some areas that are kind of questionable, and that could be brought forward in the plan.
"(Precipitation) is going to be changing, but we don't know how or to what degree. It's a moving target that no one can put their finger on."
The Federal Emergency Management Agency (FEMA) is in charge of setting the parameters for 10-, 50- and 100-year storms, according to Calvert.
"Ten-year storms, that's typically what we use for local drainage," Calvert said. "So stuff like drainage along streets and localized areas, we'll make sure those areas accommodate at least a 10-year storm event, which are obviously more frequent. And they'd be able to safely pass a 100-year storm, but that does not necessarily mean that the street is not partially flooded in a 100-year storm.
"Most storm sewer pipes are designed on a 10-year storm basis, just from a cost perspective."
And, given West Linn's hilly topography, some areas are vulnerable no matter how the stormwater system is designed. Recent flooding at a home on Burns Street is just one example.
"Water came down the street, rolled down into their yard, and the way their yard was designed, it didn't have anywhere to go but towards their house," Calvert said. "And, boom, flooded their house."
What many don't know, according to Calvert, is that flooding is not covered by homeowner's insurance.
"Typically a homeowner's insurance policy will sometimes cover a backup of sewer or drains, but not flooding," Calvert said. "It's required that you get flood insurance when you're in the floodplain, but you can actually get flood insurance anywhere in the city. ... I think people need to be cautious and understand flood insurance, and what it's there for and if it's practical or worth it for them."
Of course, the updated stormwater plan will be intended to protect residents with or without flood insurance — particularly amid an ever-shifting climate.
"(We want to) make sure we can minimize impacts to other properties from stormwater," Axelrod said.
"If anybody has locations that they have stormwater concerns or issues about, please let us know now," Calvert said.
By Patrick Malee
Assistant Editor, West Linn Tidings
Pamplin Media Group
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