The Newberg business is recognized by industry group for its work on flood control and wetlands mitigation in Tillamook

PHOTO COURTESY OF HBH CONSULTING ENGINEERS - HBH Consulting Engineers won an award for excellence in engineering design for the Southern Flow Corridor project constructed in the Tillamook Bay area.

HBH Consulting Engineers in Newberg recently celebrated completing a revolutionary construction project that earned the company two awards for its work.

In January, HBH received an award for excellence in engineering design from the American Council of Engineering Companies for its Southern Flow Corridor project in Tillamook.

"They have multiple award levels. We competed with a lot of other projects, including the Newberg-Dundee bypass," said Andrey Chernishov, principal engineer. "They look at primarily engineering excellence … out of ordinary and projects that help the civil engineering industry advance."

The firm also earned a Phoenix Award, which recognizes environmental cleanup projects in the Pacific Northwest.

"This project was voted the best for hazard cleanup for this region for 2017. I don't know how to express our appreciation to those that voted to make this project as prestigious as it turned out. We worked hard," Matt Henry, HBH Consulting Engineers president, said.

The challenge of the Southern Flow Corridor project was to solve several different and possible conflicting problems at once, to reduce flooding in Tillamook Bay and Highway 101, to restore 14 miles of prehistoric salmon-bearing streams while working with the ecosystem of 3,000 acres of flood area to restore it back to a natural wetland.

"The project was unique because it covered both the flooding and wetlands," Henry said. "Typically these two things are not done in conjunction with each other, when you are trying to reduce flooding, you sometimes destroy wetlands or habitat and sometimes when you try to protect habitat you make things worse."

In order for the project to be successful the company had to work with more than 100 stakeholders and hold several meetings with fishermen, farmers and all levels of governments.

The project originally started a couple of years after the recession began and was part of an Oregon Solutions project through the governor's office.

"Betsy Johnson, the senator for that area, she took hold of the project from a political and funding standpoint," Henry said. "Without her this project would not have existed. There was a lot of inner agency corporation and Tillamook County had a large part in this project, as did the port of Tillamook Bay."

In order to reconnect 550 acres of floodplain to two of Tillamook Bay's most productive salmon-bearing streams, the Wilson and Trask rivers, they lowered the levees that constricted the natural river channels and disconnected them from their historic floodplains. The corridor was prone to frequent seasonal flooding impacting individual landowners and Tillamook County. Between 1996 and 2000, Tillamook County accrued more than $60 million in flood damage to homes, farmland, businesses and infrastructure.

"Large storm events cause increased flows in these rivers, which breach and start flooding across Tillamook County," project manager Matt Del Moro said. "Lot of the flooding that happens goes across Highway 101 and shuts down traffic access to Tillamook. It has been flooding for at least 30 to 40 years and over the years it has gotten worse because everybody along the river each did their own thing."

Setting the levees back inland further created more area for the rivers to drain into and reduce the amount of time that Tillamook area would be flooded.

"The other aspect of that was to dig tidal channels in this whole farmland to essentially turn it into a wetland rehabilitation project," Moro said. "The land used to have native channels; when farmers owned the land they put the levees up and turned it into farmland."

They created an 85-acre easement to allow high flows to pass directly into Tillamook Bay and the flood elevations would be reduced across the area. As the result, 550 acres of tidal wetlands would be restored.

It took HBH more than three years to complete design of the project and construction began in May 2016 and was completed in October 2017. Shortly after completion, Tillamook suffered a large storm with overnight downpours snarling traffic and closing the highway and businesses. The Wilson River surged five feet beyond flood stage and crested at 17 feet.

"One of the things that everyone was waiting and anxious to see was how the flooding was reduced," Moro said. "Unfortunately, we can do a lot of modeling, but sometimes the best way to see how successful it is, is to have a flood. … Within a few weeks after completion they did have a flood and it did flood across Highway 101, which was expected. The goal was not to prevent the flooding but to reduce the amount of time Highway 101 was closed and that it certainly did. They noted that all the flood waters receded from the highway within a day or two. There was a noted significant impact."

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