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Erosion problems cut deep on Bull Mountain

Erosion poses risks to houses and streams, Tualatin Riverkeepers says


by: TIMES PHOTO: JONATHAN HOUSE - Bull Mountain resident and ecologist Paul Whitney stands in large runout caused by erosion below one of Bull Mountains neighborhoods.by: TIMES PHOTO: JONATHAN HOUSE - The backyard of a home on Gallin Court is sluffing away into a nearby stream. The city purchased the house last year after the homeowner threatened a lawsuit due to erosion problems.In a quiet Bull Mountain neighborhood sits a house you probably didn’t know you owned.

Tucked off Southwest Gaarde Street, the house at 13001 S.W. Gallin Court was purchased by the city of Tigard last January for more than half a million dollars.

A “beware of dog” sign still hangs on the gate outside the 2,800-square-foot home. Through a window, a desk chair sits alone in a small den.

But it isn’t the three-bedroom, three-bath layout that interested the city.

It was the backyard — or at least what’s left of it — after portions slipped away down into a creek bed several feet below.

It is the latest in a smorgasbord of projects that have popped up in the past few decades as the city works to address several issues of erosion across Bull Mountain.

Brian Wegener, advocacy and communications manager for Tualatin Riverkeepers, has had enough.

Wegener said erosion has gotten so bad on the mountain that it has become a risk to homes and nearby creeks and streams.

“All this volume is coming at an unnatural rate,” Wegener said. “It’s not just right here, but downstream that these impacts are happening.”

by: TIMES PHOTO: JONATHAN HOUSE - A residence on Bull Mountain has been forced to sandbag the edge of its property due to erosion worries.

Case-by-case basis

Almost since people started moving to Bull Mountain, there have been complaints of erosion.

When large amounts of water from roofs and roads are added to a stream, it can cut deep channels into the ground, eating away at nearby soil.

That ground is often someone’s property, and the erosion slowly chips away at yards, causing damage to properties and potential damage to homes.

“If I lived in those houses, I would be terrified,” said Paul Whitney, a wildlife ecologist who lives on Bull Mountain.

The city doesn’t normally get involved in erosion issues on private property, said Tigard’s Public Works Director Brian Rager. Buying a house on a steep slope, like Bull Mountain, comes with inherent risks, including erosion.

“From the city’s perspective, we don’t normally get involved in private property issues,” Rager said. “If we did, we’d be all over the place, and we don’t have the bucks for that.”

But the city does take on projects when they begin to threaten city infrastructure. Several sewer lines are buried along creek beds, which can be exposed by heavy erosion.

“Will we chase every single eroding creek bed? Given our current funding, likely not,” Rager said. “We attack them as we have the funds to do it.”

The issue isn’t limited to Bull Mountain. Erosion is a natural part of the job when it comes to maintaining cities. Last summer, work crews addressed erosion problems on Dartmouth Street on the other side of the city.

But Tigard plans to spend $1.76 million on sewer stabilization work on Benchview Road by the end of the year after erosion seriously endangered a sanitary sewer line in the area, according to the city’s 2014–2018 Capital Improvement Plan.

And it isn’t alone. Wegener estimates there are probably a dozen sites the city needs to deal with on Bull Mountain, totaling several million dollars.by: TIMES PHOTO: JONATHAN HOUSE - This waterfall and stream were caused by erosion near Benchview Drive on Bull Mountain.

Stricter regulations today

For most people, it’s a difficult problem to see, Whitney said.

“I talked to a guy the other day, and he said there aren’t any erosion problems on Bull Mountain,” Whitney said. “People just don’t see it.”

Most of the erosion spots are in hard-to-reach areas behind neighborhoods or down deep gullies behind homes.

That’s not the case on Ascension Trail, a popular hiking path on Bull Mountain that Wegener calls the “poster child” of erosion problems after water cut a deep gulley from a neighborhood near Essex Drive down the trail and into a nearby creek several yards away.

Wegener said the problems on Ascension Trail are a direct result of poor planning.

When neighborhoods are designed, developers determine how much water will be generated from roofs, streets and other areas.

All the water would normally be absorbed into the soil, but when neighborhoods are built, the water has no place to go.

“All that water has to go somewhere,” Wegener said. “And they are putting it all into a creek that can’t handle it.”

The storm water runoff is so bad in parts of Bull Mountain, Wegener said, that not long after it was built, Ascension Drive looked more like a river than a city street.

“The first big storm after the development, the storm sewers flooded, and it blew the manhole covers off,” Wegener said. “Water came pouring down the street.”

But Rager, the city’s public works director, disagrees that the city is to blame.

“The notion that the city goofed up or didn’t manage storm water well, I take issue with,” Rager said. “We simply imposed the rules that are given to us — federal, state and local.”

Rager admits there is significant erosion on Bull Mountain, but said the area was developed to the standards in place at the time — before modern rules about how to handle storm water were established.

In the 1990s, Rager said, the plan was simple: Pump it into the nearest creek.

“Back then, developers were allowed to pick up storm water in the street, put it in a pipe, and it was perfectly legal and OK to discharge the water into the natural drainage ways,” he said. “That’s how it was done everywhere, and we’ve had some problems with that, that we have had to deal with.”

That’s not the case today, Rager said, where there are much stricter regulations in place about how to handle storm water, and how close homes can be built to creeks and streams.

“Those rules change over time for good reason,” he said.

Two years ago, the city installed large pipes along Ascension Trail in order to carry the water from the neighborhood to a detention area without causing further erosion to the hill.

The long snake of pipe is anchored to trees and other natural elements along the path.

It looks temporary, but Rager said the installation should help neighbors for the foreseeable future.

“It serves its purpose,” Rager said. “It’s not real pretty, but it’s taking care of the problem, and we think it will be OK.”

by: TIMES PHOTO: JONATHAN HOUSE - Sandbags line the side of a home on Gallin Court.

City to finish work

A half mile away, work has yet to begin at the house on Gallin Court.

The city began getting calls about erosion problems in that area in the late 1990s, not long after the developers finished work, Rager said.

Neighbors complained that their backyards were starting to sluff off into a creek that ran behind the home.

The city got involved in that case because a sanitary sewer line was threatened by the eroding soil, Rager said

In 2002, the city embarked on a large slope stabilization project in the area. Crews cut into several backyards, making more gradual slopes that were more difficult to erode, Rager said.

But 13001 Gillan Court was not included in that work, because it was not located near the city’s sewer pipeline, although it had significant erosion problems of its own.

The homeowner complained that a nearby culvert was discharging water behind the home into a creek and was causing substantial damage to his property.

Rager argues that the city’s pipe was likely not the cause of the problem, but Tigard ended up purchasing the property in 2013 because it was cheaper to buy the house and fix it, than litigate over it, Rager said.

The final price: $515,000.

That’s not counting the work the city will need to do to fix the erosion problem, which is slated to be addressed over the next five years.

Rager said the city plans to remove the culverts completely and “restore a natural look” to the creek that will handle the flow of water. It may also need to cut away some of the backyard in order to give a more gradual incline to the creek.

Once that is taken care of, the city plans to put the home back on the market, Rager said.

“The homeowner proposed a very expensive retaining wall system, and we thought it will be a lot easier to deal with this in the big picture to purchase the house,” Rager said. “We’ll go do this work and then sell the house when it’s done. We are fairly confident we can do this without compromising the house."

by: TIMES PHOTO: JONATHAN HOUSE - Tualatin RiverKeepers Brian Wegener checks out a stream caused by erosion on Tigards Bull Mountain.

River Terrace planning underway

Brian Wegener and Paul Whitney said the city needs to take steps to ensure erosion problems don’t happen again on the western side of Bull Mountain, where planning is already underway.

Stretching along Roy Rogers Road from Scholls Ferry to Beef Bend, the city of Tigard annexed the area known as River Terrace in 2010. The area is currently underdeveloped but is expected to explode with new development in the next few years. Wegener wants to ensure the problems on Bull Mountain aren’t repeated in River Terrace, or other soon-to-be developed areas, including North Bethany or nearby Cooper Mountain in Beaverton.

It’s an argument Brian Rager, public works director, has heard before.

“I hear from a lot of folks who are concerned about River Terrace,” he said. “What I hear is, ‘What are you going to do to not end up like the other side of the mountain?’”

Rager said more stringent rules in place today will go a long way to making sure erosion doesn’t play as big a factor this time around.

“That fact alone will give you a different result,” he said.

Today, Rager said, developers must analyze how their developments will impact creeks downstream.

“There are restrictions, and they have to provide some kind of (water) detention,” Rager said.

But there are some complications with River Terrace, Rager said.

The southeastern edge of the site is steep, rocky and has limited ability for onsite detention.

“We can’t carve out a hole to hold the water back,” Rager said.

Planners have proposed upgrading the stream itself, so that it can better handle the amount of water that will be going into it, or piping the water from the troubled area to a more manageable place downstream.

Whitney, who is helping to plan development in River Terrace, said that isn’t doing enough.

Whitney said if the city doesn’t handle its storm water runoff correctly, it opens itself up for litigation in the future.

“The city can either pay now, or pay later,” Whitney said. “If they are talking about $20 million worth of fixes on Bull Mountain that they can’t afford, it’s going to impact people, and there will be lawsuits.”

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