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Loutsis Creek Fish Passage - Duvall, Washington (2020)

Enhancing Fish Passage with Composite Bridge Design

Project Highlights & Key Takeaways

Bridge System: Composite arch bridge using Fiber-Reinforced Polymer (FRP) tubes by Basalt International
Project Goal: Replace a 5-ft concrete culvert with a 51-ft composite span to restore fish passage
Habitat Restored: 3.1 miles of upstream habitat for Coho salmon, steelhead, and cutthroat trout
Installation Speed: SR 203 reopened in 34 days-half the time of comparable steel/concrete projects
Sustainability: Reduced concrete by ~90% and incorporated Type 1L low-carbon cement
Carbon Impact: Lightweight FRP materials cut transport emissions and equipment needs

Key Stakeholders

Owner: Washington State Department of Transportation (WSDOT)
Contractor: Goodfellow Bros., Inc. (GBI)
Material & Technology Supplier: Basalt International
Ecosystem Impact: Restored 3.1 miles of upstream habitat for Coho salmon, steelhead, coastal cutthroat trout

Recognition & Performance

Received AGC/WSDOT Honorable Mention and ASCE Local Civil Engineering Achievement awards
100-year service life with minimal maintenance and no corrosion

Project Summary

The Loutsis Creek Fish Passage project replaced an outdated concrete culvert beneath State Route 203 with an advanced composite-arch bridge system supplied by Basalt International. The transformation unlocked vital habitat, minimized traffic disruption, and delivered a high-performance infrastructure solution. The project cost approximately $4 million.

Challenge: Legacy Barrier to Fish Migration

A 5-foot-diameter concrete culvert embedded ~40 ft beneath the roadway blocked migrating fish in the Snoqualmie River watershed.
Thousands of similar culverts across Washington fragment aquatic habitats, hinder fish passage, and contribute to ecological decline.
Conventional culverts prioritize drainage over ecosystem function-resulting in unnatural flows, sediment issues, and mobility barriers for fish.

Solution: Composite Arch Bridge System by Basalt International

Innovation in design and materials:

The system uses lightweight FRP (Fiber-Reinforced Polymer) tubes, each weighing approx. 300 lbs, allowing manual or forklift-based handling instead of heavy cranes.
Transport logistics optimized: The arch structure was delivered in segments to avoid oversize permit issues. Assembly and installation occurred within 24 hours.
Span: A 51-ft wide bridge replaced the original ~6-ft span, enabling restoration of a natural floodplain and habitat corridor.
On-site technical support from Basalt International ensured precision during tube installation, decking application, and concrete fill.

Sustainability & Performance Highlights

Concrete usage reduced to ~10% of what a conventional buried arch would require.
Adaptation of Type 1L low-carbon cement in fill reduced embodied carbon while maintaining performance.
Project re-opened SR 203 after just 34 days-significantly shorter than comparable structures (60+ days).
Composite system projected service life exceeds 100 years, with minimal maintenance.
Enhanced resilience: corrosion resistance, seismic adaptability, reduced soil-settlement risk.

Differentiation vs. Traditional Structures

Feature	Conventional Buried Arch	Basalt International Composite Arch
Installation time	60+ days	34 days
Corrosion/maintenance	Susceptible	Corrosion-resistant, minimal upkeep
Carbon footprint	High (Portland cement intensive)	Low (FRP + low-carbon concrete)
Lifecycle	~50-75 years	100+ years
Transport weight	Heavy / oversize	Lightweight / permit-free

Outcome & Impact

Restored 3.1 miles of upstream fish habitat.
Traffic reopened in 34 days-reducing user-delay and community disruption.
Recognitions: Honorable Mention (AGC/WSDOT) and ASCE Local Outstanding Civil Engineering Achievement (Structures).
WSDOT has since replicated insights from this project across dozens of high-priority fish-passage sites.

Conclusion

The Loutsis Creek project-with Basalt International's Composite Arch Bridge System at its core-demonstrates how engineered materials and ecosystem restoration can converge. With a lightweight design, low-carbon materials, and streamlined installation, the project offers a blueprint for sustainable infrastructure that supports both mobility and biodiversity.

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Trust the Testimonials

Stronger and Lighter, Naturally

"Composite materials like fiber-reinforced polymer (FRP) rebars offer higher tensile strength than Grade 60 steel at just a quarter of the weight—and unlike steel, they don’t corrode. This leads to longer service life for concrete structures. Among the various fibers used in FRP bars, basalt fiber stands out as a naturally sourced and sustainable alternative."

Alvaro Ruiz Emparanza

Ph.D., P.E.; Founder & CEO, Ecotori, LLC

Streamlined Our Process

"Using basalt rebar streamlined our tilt-up wall construction process, offering exceptional ease of use compared to steel rebar. Its lighter weight, easy handling, and resistance to corrosion have translated into substantial labor savings, allowing us to achieve efficiency without compromising on structural strength."

Brian Pratt

COO, McGarvey Development Company

Stronger And More Durable

"BFRP rebar is stronger and more durable than the minimum criteria set for GFRP bars and appears to be a viable alternative as a non-corrosive rebar option."

Steven Nolan

Office of Materials, Florida Department of Transportation

Same Building Method

"Whenever you introduce a new technology like this, contractors don’t always jump on it because there’s a fear that it’s going to be difficult to build. One of the beauties of [our composite bridge system] is that it’s built exactly the same way as you would build a steel girder or a concrete girder bridge."

Bill Davids

Chair of Civil and Environmental Department, University of Maine

Lighter Means Faster

"A lot of our time-saving activities once we got to the superstructure were absolutely governed by the weight of the girders themselves and the ability to do more things at once"

Brian Emmons

Project Manager, T Buck Construction

Expertise and Experience Drive Innovation

"Under a new $20 million ARPA-I inaugural grant, our team, along with BI engineers, are exploring the uses of Basalt fibers in bridge decks and girder construction to reduce cost, cut construction time, and enhance durability. We plan to take these innovations into the AASHTO code."

Dr. Habib Dagher

Advanced Structures and Composites Center, U. of Maine

Faster Than Expected and No Issues

"Even though we knew this would be erected really quickly out in the field, the speed surprised us. It didn’t take very long for them to get their tubes in place, to get all the decking in place and start the backfill process. When you walk into a brand-new product like this, there is a certain level of risk. But there were just no issues at all with the construction."

Mark Gaines

Washington State DOT Bridge & Structures Engineer

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