Project Location: Tacoma, Washington

Client: Pierce Transit

Construction Cost: $1.6 million

Wilder’s Role: Prime

Construction Period: 7/95 – 5/96

Demolition, disposal, soil remediation and grading of two blocks in downtown Tacoma for the construction of the new Pierce transit Tacoma Dome Station.  Prior to demolition, Wilder removed asbestos insulation and disconnected power, phone, water and sewer services.  Demolition work included the removal of six existing brick, wood and concrete masonry unit buildings varying in size and height up to six stories tall.

Several buildings were supported by creosoted pile, which were exposed and cut off one foot below ground level.  Several of the larger building foundations were 25 feet below ground level on the upper portion of the sloping property.  Removing these buildings and foundations required 25-foot vertical cuts against the sidewalk and active street.  A 250,000-volt live power line adjoining the street complicated the demolition.

Wilder’s subcontractor performed a technical demolition of the buildings using an excavator with an 80-foot long boom and an articulated attachment to salvage the large timbers.  Concrete foundations and pile caps were demolished with excavators equipped with hydraulic breakers.  Wilder used a float tank to remove wood fiber from demo debris. Following demolition, Wilder provided assistance to characterize the job site. 

Characterization led to excavation of 19,000 CY of soil contaminated with hydrocarbons.  Seven underground storage tanks were discovered including an eight-foot by eight-foot by forty-foot long concrete tank completely full of Bunker C oil.  Wilder had the tanks drained, cleaned, and demolished or removed.

The soil was treated on site using thermal desorption.  The treated soil was then backfilled and the site brought to grade.  Storm sewer and sanitary sewer lines were placed on site and in the public streets.