Officials say the asphalt rubber chip seal, a repaving alternative, should improve over time.

A new street treatment has some residents of north Tigard's Summer Creek area unhappy.

During its street paving and sealing work this summer, the City of Tigard elected to try something different to improve Summer Crest Drive, Manzanita Street, 114th Place and 116th Avenue. On Aug. 7, contractors laid down what is called an asphalt rubber chip seal, a street treatment used regularly in Clark County, Wash., among other places, but never before used in Tigard, according to city officials.

Normally, Tigard treats most residential streets that show signs of pavement deterioration with a slurry seal, an emulsion spread across a roadway to form a smooth new layer of blacktop.

Mike McCarthy, Tigard's traffic engineer, said that in the case of Summer Crest Drive and the other roads treated with the asphalt rubber chip seal, pavement cracking was too extensive for them to be candidates for a slurry seal — meaning that in order to improve them, the city was looking at repaving them altogether.

"The street was in really poor shape before," McCarthy said.

TIMES PHOTO: MARK MILLER - The contrast between the road surfaces on Summer Street, left, and Summer Crest Drive is unmissable. Black asphalt chips from the rough, recently sealed surface of Summer Crest Drive have been kicked up, although street sweepers come through regularly.

Road surface is unpleasant to walk, bike on

Three weeks since the asphalt rubber chip seal was laid down, Summer Crest Drive shows no signs of cracks. That's the good news. The bad news is that the street's surface is rough and rocky, resembling a gravel road if the gravel were partially embedded in a tar-black, solidified mixture of oil and rubber, and asphalt chips from the surface layer are still being kicked up by traffic, finding their way onto curbs and driveways.

To Summer Crest Drive resident Amy Chamberlain, her own street has become forbidding.

"My dog's gait changed the first time she walked on it. … It might have been because of the curing process, but still, I'm not comfortable walking her," Chamberlain said. "I wouldn't walk on it with bare feet."

She doesn't have children of her own, she added, but she has spoken with neighbors whose kids have stopped riding their bicycles on the street for fear of injury from the rough surface.

Chamberlain fought back tears as she addressed the Tigard City Council at a meeting last Tuesday, Aug. 22, along with neighbor Carmen Cordova. She presented a petition she said had collected 56 signatures from residents asking the city to take action.

"I have been shocked by my own emotional response to this," she told The Times afterward.

Cordova offered an example of how the road resurfacing has affected the way she and her neighbors go about their lives this month.

"I live around the bend from (Chamberlain), and it's so fun, because she'll be walking with her dog and then she'll come up and say hi, and we'll hang out, or maybe even have a glass of wine or something. But that's stopped," Cordova said. "Honestly, the culture of the neighborhood has changed — and it shouldn't because of something they put on the street."

Tigard officials, from Mayor John L. Cook on down to City Hall employees like McCarthy, have heard the complaints from residents like Chamberlain and Cordova. Eric Zimmerman, who has been assistant city manager since early July, said he has been out to see the road conditions for himself and has offered to meet with residents of the neighborhood.

"I think we did do some outreach, and I think that was good, but we can always improve it," Zimmerman said, adding, "I think that's a really valid point that folks have raised as well."

Asphalt rubber chip seal a much cheaper fix than repaving

The city has defended the decision to contract with Intermountain Slurry Seal Inc. for the pilot project by noting the cost savings could allow it to address its 22-mile backlog of deferred street maintenance several times faster, if the asphalt rubber chip seal is determined to be a success on Summer Crest Drive and the other treated streets.

McCarthy estimates the asphalt rubber chip seal treatment costs about $100,000 per mile. In fact, he noted, the contract with Intermountain to seal about 1.2 miles of city streets on Aug. 7 — using some 2,500 recycled tires, according to Jason Lampley, Intermountain's regional manager — was awarded for about $90,000.

Lampley and McCarthy described the asphalt rubber chip seal as being approximately double the per-mile cost of slurry seal, which McCarthy said doesn't work well on streets like Summer Crest Drive where the pavement is cracked. But it's a fraction of the cost of repaving, which McCarthy said costs the City of Tigard about $500,000 per mile.

"We're trying to get to this backlog for a lot less money, as a way that we can try and address the backlog with the funding that we have," McCarthy explained.

And city officials say they believe the condition on the treated streets will improve over time. While a roller is used during the installation of the asphalt rubber chip seal to press the asphalt chips down into the rubberized base layer, traffic and other conditions are expected to flatten the surface texture out further, Lampley said.

"They smooth out over time, typically," Lampley said of the asphalt rubber chip seals. "The traffic really does it."

McCarthy said they are monitoring to ensure the surface roughness improves and that no cracks develop in the new seal. In time, he said, the hope is that the roads will be deemed in good enough shape to be resurfaced with a smoother slurry seal, although he admitted that might not happen for years to come.

"It's certainly rougher than your traditional neighborhood street," Zimmerman acknowledged. "Like, we can see that. We know that. But it also does — and has over the course of these last couple of weeks, has started to — form in, settle down."

He added, "We're kind of in a 'patience right now' mode, if you will, so we can evaluate what does it turn into after people are driving on it. But if it works, what it could offer us in the city is a hundred-thousand-dollar-per-mile solution to roads that may otherwise not be on our list for repaving at half a million dollars per mile, because of them being in too low of a (traffic) capacity."

Chamberlain said she understands what the city is trying to do by testing out the asphalt rubber chip seal method. But she is frustrated that it has resulted in unpleasant road conditions, at least for the short term.

"I do appreciate the city looking for cost-saving measures, because that's an important thing to do," Chamberlain said. "However, everything that was outlined in their response (Aug. 22) should have been done before it even started. They should have had the answer to how long it will take. The mayor responded to me that the truth is that it may improve over time. My question back is, what truth is there in that statement? The truth is that it may improve over time, the truth is it may not."

Cordova added, "I definitely encourage finding appropriate cost savings, but there's also times when you get what you pay for."

COURTESY OF THE CITY OF TIGARD - Marked in red are the streets treated with an asphalt rubber chip seal, a lower-cost method of addressing badly deteriorated streets that the City of Tigard is trying out, by Intermountain Slurry Seal Inc. on Aug. 7.

City still assessing outcome of pilot project

There's nothing particularly unusual about the result of the asphalt rubber chip seal in Tigard, Lampley indicated: Road surfaces in the weeks following the treatment are rough.

Asked what residents can expect to see after a month or so, Lampley answered, "A month from now, it's not going to change a whole lot. … It's going to take really a season to get through it."

The city sent out notices to people living along the affected streets with a brief description of the asphalt rubber chip seal process and directions on what to do during the Aug. 7 sealing work. The notice, a copy of which was provided to The Times, notes that residents can expect "a few weeks for the street surface to fully cure," adding, "Some loose aggregate may be present during the curing time, and will be picked up by sweepers in a few weeks." It does not mention the rough road surface that results from the sealing process.

Asked whether he believes the city could have done a better job preparing residents, McCarthy answered in the affirmative.

"In hindsight, I think we could have helped people understand what to expect a little better," he said.

McCarthy and his staff are still evaluating the asphalt rubber chip seal — they have not yet declared it either to be a success or a failure.

"I think it's too early to say," McCarthy said. "We're looking at any way to address the backlog of streets. … We really want to get these streets taken care of. But whether this would stay in the toolbox or not is yet to be decided."

Lampley said he "absolutely" stands by his company's work. In fact, he said, Intermountain typically receives few complaints about its asphalt rubber chip seal installations relative to other street treatments, as he noted the method has the "least impact to the traveling public on production days, and really the long-term performance is better."

Of the Tigard project, Lampley said, "We haven't heard any complaints into our office."

Lampley described the asphalt rubber chip seal as the "kind of the Cadillac" of street seals, the family of methods to address deteriorating roads without fully repaving them.

While a slurry seal often fails after six to seven years, Lampley said, an asphalt rubber chip seal can be expected to last for 12 to 15 years — in other words, while the price is roughly double, so is its lifespan. The asphalt rubber chip seal can also be used on roads in worse condition than those a slurry seal can address, and it allows the road to reopen much sooner. Furthermore, compared to other types of chip seals, the rate of "aggregate retention" — the percentage of chips that stay in place, rather than being kicked up from the surface — is significantly higher, Lampley added.

Editor's note: This story has been updated to better reflect residents' concerns about bicycling on the streets treated with the asphalt rubber chip seal, as related by the petitioner.

By Mark Miller
Assistant Editor, The Times
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