Stormwater standards complicate community center

March 1, 2014

By Ari Cetron

During a big rainstorm in the 1970s, Ebright Creek overran its banks and flowed into the nearby Zaccuse Creek, flooding the basement of Wally Pereyra’s neighbor.

At the time, Pereyra drove out on a tractor, pushing earth around and trying to put the creek back where it belonged. Now, he fears that the new Sammamish Community Center might cause a repeat performance.

The city is in the process of granting itself permits for the community center, which sits near the headwaters of Ebright Creek, and officials are poised to allow a deviation from city standards about how much water can flow off the land.

Pereyra, and at least one member of the City Council, question whether the city should grant itself the leeway.

“The city, which should be, really, the model, is applying to give itself a deviation,” Pereyra said.

Pereyra has a Ph.D as a fisheries biologist, and he understands the impact development can have on water bodies.

He is known for spending $175,000 of his own money to help restore the part of Ebright Creek that runs through his property.

While he doesn’t think the community center will damage the work he did, he does fear for the overall health of the stream.

The entire process is new, since the community center is the first thing to be built in the Town Center area.

Until recently, guidelines in that area said developers should try to remove 100 percent of the water from their development (see sidebar) when practical.

When the City Council established that goal, it knew it was an aspirational one, since containing all of the water that runs off a property is next to impossible.

“We realized it would be pretty hard, but we thought it would be good to get people to try,” said Eric LaFrance, the city’s stormwater engineer.

As the city has gone through the process, acting as its own guinea pig, officials have realized just how challenging the goal is. Much of the soil in Sammamish is glacial till, which is very densely compacted. With that type of soil, water tends to run off a property instead of filtering down into the ground.

As a result, the council voted in November to reduce the standard from 100 percent to 60 percent — and 80 percent near Ebright Creek. But the city continues to require it only when practical.

It’s the “when practical” part that worries Pereyra.

“As far as I’m concerned, it means there’s no regulation,” he said.

Pereyra also fears the precedent the city will be setting.

If the city decides, for its own project, that “practical” means retaining a certain amount of water, it may be difficult to argue in the future that private developers would have to retain more.

“Each little development adds a little bit more,” Pereyra said. “It’s like the old Chinese proverb, death by a thousand pricks.”


How does it work?

In theory, it would be possible for someone to remove all water from their property. In an example intended to be unrealistic, LaFrance explained to the City Council that someone could collect the water from a site and load it onto tanker trucks to remove. While possible, it would not be practical or cost-effective, so it would be unreasonable for the city to ask someone to do it.

While King County has specific guidelines for how much something could cost and be considered reasonable, Sammamish does not.

“This is kind of new for both staff and developers,” LaFrance said.

It would be up to the Community Development Department to issue the necessary permits.

Evan Maxim, of Community Development, said his department has not yet determined whether it will grant the needed deviation from the standards. He expects it to be part of the larger permit package issued for the community center, which should happen within the next couple weeks. Until the final permit is issued, it will be unclear just how much will be retained.

Since the guidelines call for removal “when practical,” the city has the authority to grant itself the permits, Maxim said.

He also notes that the definition of “practical” is tough to get at.

Certainly, there could be a way for the city to detain all of the water, but doing so is not always worthwhile.

During a November 2013 council meeting, Councilman Ramiro Valderrama questioned the city granting itself a deviation. No one had calculated how much it would cost to detain all of the water, so Valderrama asked how the city could know it would cost too much.

In an interview, Maxim explained that city officials didn’t have to go through the exercise of finding how much it would cost to realize that nothing practical would work. He said that the prospect of detaining all of the water would involve a very high cost with a very low probability of success.

“What we’re talking about is diminishing returns on the money spent,” Maxim said. “We’re not sure that actually adds value.”

He also noted that right now, the water coming off the area is not treated at all, and that adding the community center will actually improve the situation in some ways.

“We’re actually reducing the volume from what it is right now,” he said.

Pereyra said it’s shortsighted to say detaining the water will be impractical. The costs are all going to be paid somehow, by someone — if not by the city at the community center site, then by the community at large in the form of the environmental degradation of the stream.

“I understand what they are doing, but it comes at a cost,” he said. “If you don’t pay it there, you’re going to pay it down here.”


New term

The process for permitting stormwater in Town Center is so new, the city administration had to invent a new term to explain it, said Evan Maxim, of the Community Development Department.

Since the rules include the term “where practical,” Maxim said allowing something with a lower standard is within the rules. It wouldn’t properly be called a variance or some kind of exception since it falls within the regulations.

But it doesn’t quite achieve what’s called for in those regulations, so city staffers have taken to calling it a deviation, Maxim said.


How much water is too much?

Adding water to a stream — beyond what the stream has evolved to handle — tends to erode the streambed and other nearby land, increasing the dirt in the water.

This means property owners who might have had a tree near a stream eventually find their tree in the stream. The extra dirt doesn’t do wonders for the fish that need to live in the stream and, essentially, breathe the water, either.

New buildings cover up some land, so water that would have filtered into the ground can’t. Instead it runs off toward the nearest water body, creating the problem of extra water.

Sammamish officials implemented standards in the Town Center proposal that sought to do more than stop things from getting worse; they hoped to improve them. The plan would turn back the clock to a time when the area was forested — actually improving the water runoff situation.

Water could still flow off a property, but no more than if the land was still a forest. Even though some water would leave the property, this is, in a way, considered capturing 100 percent of the water.

The goal was to force development to have a smaller environmental impact, called low-impact development. There were not yet formal standards for this, so the city did what it could to approximate them.

“This was all a proxy to get at low-impact development,” said Eric LaFrance, Sammamish’s stormwater engineer.

City officials realized a 100-percent goal was unrealistic, so in November 2013, they set their goal back and asked property owners to capture 60 percent of the water (80 percent in the Ebright Creek basin).

In the community center project, the city should be able to reduce the volume of water running off, but would extend the time the extra water is flowing.

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One Response to “Stormwater standards complicate community center”

  1. Craig Krueger on March 3rd, 2014 8:51 am

    It would be interesting for the City to look at all the properties that are currently draining to the creek. My guess is that much of the current development may provide little storm water detention prior to releasing it into the creek since the storm drainage standards have evolved and increased over time to make up for past actions Perhaps the City could look at creating a storm water district to retrofit some of the existing neighborhoods to provide this detention, paid for through property taxes on the affected properties.

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