To meet current engineering standards and improve riparian and aquatic habitat, Aspect is providing geotechnical services for the replacement of a levee and river revetment for a 1.4 mile length of the Lower Russell Road flood protection system along the east bank of the Green River in the City of Kent. The project will improve flood protection for the residents and businesses of Kent, Tukwila, Renton and the Green River valley. Aspect Consulting is the lead geotechnical engineer for the project. They completed field investigations to characterize the subsurface conditions in support of the design and construction of the new levees and ecosystem restoration features. Aspect is completing seepage and slope stability analyses for levee design, and providing geotechnical recommendations for levee embankment material, roads, utilities, and habitat features. The project objectives include designing a system that minimizes long-term maintenance needs and associated costs, and balancing policy directives regarding flood protection (e.g. scour protection, stability and vegetation maintenance), habitat restoration, and recreational use.
Quick action was required to prevent an imminent release of refuse to the marine environment from a landfill perched atop a rapidly eroding high coastal bluff above the Straits of Juan de Fuca. We met the challenges posed by the site’s complex geometry with design elements including: aggressively steep cut and fill slopes (2.5H:1V) in refuse and a 110-foot-high mechanically reinforced earth buttress to stabilize the seismically unstable slope, a new cover system with a bentonite-amended low-permeability soil layer below a synthetic turf cap, and shoreline stabilization seawalls and revetments. Successfully accelerated, the project was completed in about half the time typical of similar projects.
Crossing below the Montlake Cut waterway and connecting the University District and Capitol Hill with downtown Seattle, the University Link extension is anticipated to add 71,000 riders to Sound Transit’s light rail system by 2030. Reducing design uncertainty and construction risks, Aspect’s geologic and hydrogeologic analyses for the 3.15-mile twin-rail tunnel and two deep underground stations contributed to the overall success of the tunnel boring project, which came in $100M under budget and 6 months ahead of schedule. Our dewatering analysis and construction oversight further helped the project sustain progress on schedule-critical construction elements.
Shaped by a glacier and eroded by floods, Madison Valley has steep hillsides and a history of stormwater flooding and sewer backups in the neighborhood. We helped address the perpetual urban flooding problem, contributing geotechnical and environmental recommendations in the design and construction of a 1.3M-gallon, underground stormwater storage tank. Our input to the alternatives analysis resulted in a tunneled alignment with several jacking/receiving shafts. Working with soft landfill soils and resolving historical contamination, we designed excavation, shoring, and deep foundations for tank support. As a result of our subsurface studies, change orders were minimized providing a degree of surety in cost and schedule. Our attention during construction further helped keep the project moving forward and on schedule while minimizing impacts to the community.
Aspect provided geologic and geotechnical engineering support for road repairs and subgrade improvements on 1.5-miles of Old Highway 97 near Brewster. We completed subsurface explorations, geotechnical engineering analyses, and pavement design alternatives including multiple subgrade improvement strategies. We provided cost-effective repairs tailored to individual problem areas while meeting WSDOT standards and local agency guidelines to fulfill funding requirements. We prepared a full geotechnical report along with design-level plans, specifications, and cost estimates for the proposed improvements.
The only road in, Fragaria Road was in danger of collapsing and thereby isolating a Kitsap County waterfront community. Responding quickly with geotechnical design to help stabilize the failing roadway, we expedited the project through repair options analysis and design; and into construction planning, bidding, contracting, and oversight. Combining soldier pile wall and driven soil nails, our design solution both met County design standards cost effectively, and was appropriately scaled to the community’s road use.
Aspect provided geotechnical design for a pile system for a new utility bridge to help restore hydraulic continuity and the marine estuary. Key project challenges included pile design within the site's soft marine sediments and re-routing utilities beneath the estuary using directional drilling technology. The project involved collaboration with several stakeholders including the Jamestown S’Klallam Tribe, project engineer, contractor, and private land owner. Aspect also provided written specifications for the foundation components of the project and construction support.
Aspect is providing geotechnical and environmental services for estuary rehabilitation and traffic congestion relief where existing twin 72-inch culverts will be replaced by a new bridge. The project includes rehabilitating the Clear Creek estuary and widening the existing two-lane road. The culverts will be replaced by a four-lane bridge along NW Bucklin Hill Road at the Clear Creek crossing to relieve traffic congestion and restore pre-existing estuary conditions. Aspect is providing design recommendations in accordance with WSDOT Local Agency Guidelines and LRFD methodology.
For more than a decade, Aspect has provided ongoing geotechnical engineering and construction services for the landslide-damaged Rockaway Beach Road site. Aspect’s local knowledge of the geology and on-going erosion processes provided the basis for the development of the roadway repair. The repair included a shoreline revetment wall, mechanically reinforced earth slope, and re-built roadway shoulder. Aspect provided expedited support and recommendations for design changes that occurred late in the project and responsive field support during construction.
Washington Boulevard, located along a steep coastal bluff, has exhibited landslide movement several times in the past decade. Aspect performed multi-phase geologic and geotechnical assessments of earth movement with focused deep-subsurface explorations. Results of the exploration and slope-stability analysis were verified with slope inclinometers and groundwater level monitoring. Based on our targeted remediation concepts and cost estimates, Kitsap County decided to add drainage improvements to enhance stormwater handling. In addition, Kitsap County implemented a groundwater and landslide monitoring program, which Aspect is effecting.
Owners of a high-end custom residence on a steep slope overlooking Lake Washington hired Aspect to provide geologic/geotechnical expertise to evaluate potential construction impacts from an adjacent property, which would have deep cuts and excavations into a slope with a landslide history. Prior to construction, Aspect reviewed geotechnical documents and helped design a slope movement and foundation settlement monitoring program. During the adjacent work, the client’s foundations were damaged because of poor construction practices and lapses in engineering oversight. A settlement awarded our client all damages and expenses.
This project incorporated the restoration of the mouth of Curley Creek along with replacement of the existing bridge. Aspect conducted geotechnical explorations, completed bridge foundation design including drilled shaft recommendations, developed liquefaction mitigation alternatives, and reviewed off-site groundwater and soil contamination concerns. We also assisted in writing project specifications and provided field observation during construction. This was the first bridge in Kitsap County to use drilled shaft foundations.