The area surrounding Union Hill Road and the Union Hill Road/Avondale Road intersection has developed rapidly and continues to grow. Union Hill Road serves as a key route to the Novelty Hill Urban Planned Developments to the east. The project’s objectives were to increase the capacity, level of service, and safety for all transportation modes and retain the character of both corridors by minimizing impacts to the surrounding environment.

INCA completed the design in two phases. The first phase of this project included updating the previous design reports and reviewing alternative channelization for the intersection along with preliminary design. The second phase involved the design of the preferred channelization alternative through final PS&E including: modifying channelization of Union Hill Road and Avondale Road at the intersection, including bike lanes on Union Hill Road; improving roadway illumination; providing intersection pavement upgrades at Avondale Road-Union Hill Road; underground overhead utilities; working with property owners to assist the City with right-of-way and easement acquisitions; coordinating with Transportation Improvement Board (TIB), King County and WSDOT; and working with property owners adjacent to the roadway to ensure the community’s concerns are identified.

A multi-purpose project combining water supply for the south Puget Sound area with ecosystem restoration of salmon habitat above and below it, the Howard Hanson Dam includes installation of a fish passage facility (FPF) at the dam. The FPF must pass fish under extremely harsh conditions, including reservoir levels that can fluctuate over 100 feet in as little as two days due to flood water impoundment. During the peak fish passage season, the reservoir pool will slowly rise to meet the water storage summer conservation pool. The FPF is being constructed in two phases. Phase 1 included in-the-wet construction of a cofferdam and a large excavation for the foundation. Phase 2 includes installing the FPF in the excavation. For Phase 1 construction, the cofferdam was ingeniously designed to integrate into the final structure and provide seasonal maintenance dewatering capabilities for the life of the project.

Tetra Tech INCA and Shannon and Wilson provided design services and prepared bid documents for new cofferdam construction and excavation for the new FPF. Features included in-the-wet construction; large heavy-lift precast concrete components; steel stoplog, lifting beam and trashrack design for over 100 feet of head; large seismic design forces including hydrodynamic added mass; finite element modeling of the interaction of the new cofferdam structure and the existing intake tower under seismic loading; extensive rock excavation near existing structures; construction adjacent to the existing intake tower which must remain operational at all times during construction; seismic retrofit of the existing intake tower for the new conditions after construction; adapting the construction schedule to the reservoir pool elevation seasonal fluctuations; preserving the water quality of this main water source for the City of Tacoma; access roads and soldier pile walls with tiebacks; and cantilever flood and retaining walls.

This project received the SAME Large Business Gold Award and the ACEC Washington Engineering Excellence Award 2008 Silver Award for Complexity.

The P&L Railroad bridge relocation allows for construction of a new longer lock at Kentucky Lock and Dam at the site of the existing bridge. The new lock and bridge will make river navigation in the future easier for barges.

Tetra Tech INCA provided design and construction services for the bridge relocation. INCA’s work consisted of providing foundation design for a 3,500-foot long, 15-span bridge structure spanning the Tennessee River. INCA’s services on this project included:

Work included the design of 11 piers, each of which included 4 drilled shafts, a 34-foot diameter shaft cap, a 10-foot diameter column, and a column cap. Drilled shaft lengths ranged from 75 to 105 feet, and are embedded in bedrock with rock socket depths varying from 25 to 42 feet. Pier heights (above the shafts) range from 72 to 82 feet.

Tetra Tech INCA as part of the design team developed structural designs for the University Street Underground Transit Station. The station is located approximately 70 feet below-ground and includes ancillary structures such as station entrances, vent structures, traction power substation, and underpinning of existing buildings. INCA prepared the preliminary and final plans for this underground station, approximately 573 feet in length.

Pier 23 is located on the southeastern shore of Commencement Bay. Originally built around 1946, the pier serves to support the equipment, personnel, and operations of the 70th Regional Readiness command of the US Army Reserves. A concrete extension was added to the pier a few years later, making the pier approximately 1,216-feet long by 56-feet wide. The landward 606 feet of the pier consisted of timber construction and the outboard 610 feet of the pier consisted of concrete construction. Tetra Tech INCA provided engineering during construction services and developed 23 construction drawings, 13 project specific specification sections, and a detailed MCACES construction cost estimate.

The existing timber portion of the pier was demolished and replaced with a new concrete pier for this project. The replacement pier was constructed of precast/prestressed concrete piles supporting cast-in-place (CIP) pile caps and precast deck panels. The new pier is approximately 600 feet long and lies between the existing concrete pier and the existing sheet pile bulkhead wall, which extends along the shore bank. The pier foundation system supports the vertical loads and lateral loads through a foundation system consisting of pile caps supported by vertical and battered piles, which transfer the load to the soil in friction and end bearing.