Understanding what's Underground

Aspect develops effective geotechnical solutions in even the most challenging underground settings. Our engineers, geologists, and hydrogeologists understand the regional geologic setting, which allows us to efficiently adapt to site-specific conditions and apply the results to cost-effective and reliable design recommendations. We minimize uncertainty and offer low impact solutions for projects involving subsurface soil and groundwater.

GEOTECHNICAL ENGINEERING

• Aquatic Habitat Restoration Support

• Bridge and Structure Foundations

• Coastal and River Revetment

• Construction Dewatering Design

• Construction Observation/Special Inspection

• Culvert Replacement

• Rivers, Levees and Floodplain Management

• Roads and Retaining Walls

• Seismic Analysis and Mitigation

• Site Development and Earthwork

• Slope Stabilization, Landslide Remediation, Shoring, Retaining Structures

• Soft Ground Engineering and Ground Improvement

• Tunnels and Underground Structures

• Water and Wastewater Storage, Pumping, and Conveyance

GEOLOGIC EVALUATION + SITE HAZARD ASSESSMENT

• Coastal and Fluvial Geology

• Geologic Hazards Assessments/Sensitive Areas Identification

• Hydrogeologic Assessment

• Land Use Litigation/legal Support

• Regulatory and Permit Assistance, EIS and SEPA Support

• Site Characterization

• Slope Stability Analysis

• Tunneling and Infrastructure Corridor Studies

LOW IMPACT DEVELOPMENT

• Green Stormwater Infrastructure (GSI)

• Hydrogeologic Support

• Shallow and Deep Stormwater Infiltration

Lower Coal Creek Culvert Replacements and Flood Hazards Reduction

Bellevue’s Newport Shores neighborhood lies on a low floodplain of Coal Creek near Lake Washington. Increased development in the area created more frequent and severe flooding of the neighborhood, due partly to five undersized culverts beneath the major roads. Replacing each culvert with a bridge will improve stormwater drainage and flow to Lake Washington and restore the creek habitat for endangered fisheries.

THE PROBLEM

HOW WE HELPED

Aspect is providing the geotechnical engineering and construction observation expertise to design and construct the five bridges along with two new stormwater outfalls. Design innovations to evaluate the deep and seismically sensitive soils include state-of-the-art methods developed by the University of Washington to evaluate large-scale lateral spreading acting on bridge foundations and options for reducing lateral loading using new-to-the-region grouted helical piles. Our team worked with the City of Bellevue to select a deep drilled-shaft foundation system and coordinated closely with the City and the other consultants to keep neighborhood residents informed of our work and progress.

Aspect also worked with the City to evaluate risks and cost-effectiveness of options for mitigation for settlement of bridge approaches using articulated approach slabs, lightweight fills, and maintenance pavement.

MILESTONES FOR THE CITY

Work is progressing, with three of the bridges already constructed and design work on the last two underway. As proof of the project’s effectiveness, salmon returned to Coal Creek this winter, and are now spawning upstream of the recently completed bridges.

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