Responding to the fall rain

From ODOT-

Fall rains can lead to erosion on any construction site. For the Willamette River Bridge project, we take several steps to minimize the effects of rain throughout the construction area.

To limit erosion on bare soil like this recently completed embankment east of Interestate 5, crews applied grass seed and mulch, hastening grass growth.

On this embankment west of I-5, established grass is filtering runoff from the road and preventing erosion.

Rainwater and runoff filter through the vegetation on the embankments, and then flow into a series of bioswales that provide additional filtration before moving into local waterways.

This bioswale collects and filters water from recent rains.

In addition, rainwater that falls on the project’s work bridge must be filtered before it enters the river or local stream.

Plastic sheeting under the work bridge's wood deck captures the rainwater. Once captured, the water is piped to a nearby filtration system to remove any pollutants.

The large filtering tank processes water from the work bridge before it enters a settling pond. Then the water is discharged into the river.

These measures ensure that construction can proceed throughout the winter, because the rainfall will have minimal impact on the project site and on local waterways.

Waterways Surrounding the Bridges

From ODOT-

Do you know that besides the Willamette River, there are 13 other bodies of water surrounding our project?



Both natural and manmade waterways flow here. The Whilamut Natural Area is home to the Canoe Canal, also known as Patterson Slough, and two protected wetlands. The Canoe Canal water originates from a diversion structure built in 1974 east of the bridge and reconnects to the river near the Ferry Street Bridge. The wetlands retain rainwater throughout much of the year, providing natural filtration and supporting a diverse plant environment.



On the south bank of the river, an interconnected network of waterways includes eight wetlands and two creeks. Three of the largest are Laurel Valley Creek, Augusta Creek and the Glenwood Slough. Water from the Laurel Hill Valley neighborhood winds through this network and flows into the river west of the bridges. Located along Interstate 5, the Franklin Boulevard off-ramp and the railroad tracks, this network captures and naturally treats rain runoff.



Before construction began, we developed plans to avoid or minimize impacts to all of these bodies of water. As part of the Willamette River Bridge project, we will improve this system through stream restoration and new bioswales that capture and treat more of the runoff before it enters the river.

Treating what nature provides

From ODOT-

On the Willamette River Bridge project, planning for the rainy season and the impacts of water runoff is very important.



The new wider southbound bridge has a larger surface area that will collect more rainwater than the old bridge did. The rainwater runoff becomes contaminated when it mixes with pollutants from vehicles, such as grease, brake dust, automotive fluids and deicing chemicals. Without containment and treatment, the runoff would flow directly into the river and nearby natural areas.



Instead, we have started collecting runoff and discharging it into a system of bioswales for treatment. Bioswales are landscape elements designed to remove silt and pollution from surface runoff. They are gently sloped areas planted with native vegetation. Runoff captured from the bridge is filtered by the vegetation or held in a grassy bowl until particles settle out. The treated water either soaks into the ground or is released into the surrounding watershed, such as the river or nearby creeks.



We have built multiple bioswales to treat rainwater runoff on or near the project site, saving the cost of collecting and piping it for discharge further away.



Building bioswales is just one of the ways ODOT is reducing the environmental footprint of the new Willamette River Bridge.