By guest blogger Chelsey Funis from Flatiron Construction

The I-405 Bellevue to Lynnwood project reuses soil moved from other parts of the project area to build retaining walls, shown above, and sections of new roadway.

Most of us follow that old mantra of Reduce, Reuse, Recycle without a second thought everyday, whether we’re recycling our used aluminum cans or bringing our reusable grocery bags to the grocery store. But did you know that crews building the latest batch of I-405 improvements are also following that mantra? 

As part of the I-405 NE 6th Street to I-5 Widening and Express Toll Lanes Project, our crews and contractor, Flatiron Constructors, are using a number of sustainable practices to build a better project for our environment and taxpayers. In this case, going green also helps us save a little green. And who doesn’t like that?

So what are we doing to reduce our carbon footprint?

To reduce impacts on nearby aquatic resources, project crews have built three mitigation sites. Improvements completed this October in Kirkland, shown above, include new trees, plantings, rocks and drainage pipes.

Recycling soil and fill material excavated from the 17-mile project site
Major construction projects typically truck in thousands of cubic yards of soil, crushed rock and other organic materials from off-site locations. Using a little creativity, we were able to design the I-405 project and schedule the construction in a way that recycles tested and approved soil and earthen fill material directly from the project site. We then use the recycled soil and fill material in other places on the job. For example, we’re building two retaining walls and a noise berm in Kirkland by reusing earthen material dug up from the footprint of a new northbound I-405 on-ramp in Bothell and other locations throughout the project area.

By reusing soil on site instead of disposing it off-site and buying new material, our crews:

• Cut back on heavy trucking at longer distances.
• Save fuel and decrease carbon emissions.
• Prevent damage to our roads.
• Reduce the cost and space used at off-site disposal locations.

Because we’re recycling and reusing soil and fill materials, we’ve also eliminated about 300,000 cubic yards of excavation. To put things into perspective, that’s enough soil to build a pile nearly 136 feet tall onto a football field – or nearly two-thirds of the way up to CenturyLink Field’s roof, which rises about 200 feet above the ground. In addition, our commitment to reusing 100 percent of the remaining excess material on site will result in a 2,100-ton reduction of greenhouse gas emissions over the life of the project. That’s the equivalent of a little more than 4,000 cars’ annual greenhouse gas emissions.

Recycling demolished concrete structures
We’re removing  many concrete structures, such as roadway barriers, so that they can be updated to current standards. For this project, crews haul all of this rubble to local recycling facilities that process and repurpose the steel and concrete for other local projects.

Recycling old asphalt pavement
We’re also removing existing asphalt pavement that is past its service life. Crews are grinding and breaking the removed asphalt to build temporary access roads and embankments, as well as reprocessing it back into new asphalt for this and other local projects.

Installing bioswales: smarter drainage ditches
Urban stormwater – the rain and snow melt that runs off surfaces like rooftops, sidewalks, paved streets, highways and parking lots – is one of the biggest environmental threats to the Puget Sound region. Left untreated, stormwater runoff can carry pollutants like oil, fertilizers and pesticides into our waterways, harming creeks, streams and rivers that provide important habitat for fish and wildlife.

Cleaning pollutants from this water and reducing the rate of runoff is a critical component to the Bellevue to Lynnwood project in order to help protect the many nearby wetlands.

To clean pollutants and control the rate of runoff, this project will construct:

• Eight new or enlarged standard treatment and detention ponds.
• 3,550 linear feet  (more than half a mile) of biofiltration swales, also known as bioswales, which help capture and treat stormwater by filtering the water through vegetated channels comprised of organic materials like grass and shrubs. 
• 11,200 linear feet, or more than two miles, of new media filter drains, which we construct along the highway shoulder area. The media filter drains consist of a no-vegetation zone, a grass strip and a mix of native vegetation. These pollutant filters are great for where there is limited space.

Want more information?

• Visit the project Web page.
• Sign up online to receive email alerts about closures and construction activities.

By guest blogger Anne Broache

If you’ve ever struggled to navigate the congested area where northbound Interstate 405 meets State Route 522 in the Bothell area, rest assured that improvements are on the way. As part of the I-405 NE 6th Street to I-5 Widening and Express Toll Lanes Project, our project crew will add a new set of ramps—called “braided ramps”—that separate traffic going from Northeast 160th Street to northbound I-405 from I-405 traffic heading to SR 522.

But before we can make this upgrade, we had to innovate to keep ramp traffic—some 13,000 vehicles daily—moving through the braided ramp construction area. To avoid repeated shutdowns of this critical on-ramp, our contractor worked this summer to build a temporary loop ramp to northbound I-405 at NE 160th Street. We’ll be able to route traffic around the construction rather than through it.

We’ll soon be ready to open that new ramp and shut down the current one.

New I-405 on-ramp at NE 160th Street opens September 8
Starting as soon as Sunday, September 8, drivers will access the on-ramp to northbound I-405 from the south side of NE 160th Street, just east of I-405 and adjacent to the northbound off-ramp from I-405.

The new entrance will be located directly across NE 160th Street from the existing on-ramp entrance, as shown in the map below.

New temporary on-ramp to I-405

The on-ramp you’re accustomed to using will remain closed until the new braided ramps open in 2015.

This temporary on-ramp has clear advantages:

• It creates a dedicated work zone for our crews. By shifting traffic off the existing on-ramp, we can give crews full access to work on the new ramps in a space without public access.
• It prevents major traffic interruptions. The temporary on-ramp will allow us to provide consistent northbound I-405 access instead of making multiple changes to the existing on-ramp as construction reaches different phases.
• It’s the neighborly thing to do. Maintaining access to I-405 around the work zone allows more construction activities to happen during daytime hours, reducing nighttime noise for neighbors.

Allow extra travel time when the new ramp opens
As with any new roadway configuration, drivers should allow extra time to navigate and approach the new on-ramp—especially in the first few weeks while drivers get used to the new arrangement. Opening the new temporary ramp depends on good weather, and we’ll be sure to update drivers if the schedule changes.  

Want more information?
Visit the project Web page: www.wsdot.wa.gov/Projects/I405/NE6thtoI5/
Sign up online to receive e-mail alerts about closures and construction activities:
www.wsdot.wa.gov/emailupdates/