Exploration for Bridge Rehabilitation
The Manette Bridge in Bremerton, Washington, was built in 1930 and is one of the oldest bridges in the state still open to regular traffic. Due concerns of structural deficiency, the Washington State Department of Transportation (WSDOT) proposed a replacement. However, with a view towards preserving the historic bridge, a local group persuaded WSDOT to do a thorough investigation of the concrete piers supporting the bridge in addition the regular visual inspections of the steel structure.
Team Members
WSDOT
Crux Subsurface
Crux’s Role
The bridge’s steel structure was supported on 1800-foot long concrete piers, approximately 100 feet above the water surface. As an on-call contractor for WSDOT, Crux drilled three horizontal HQ borings and two, 4-inch masonry holes at various elevations into one of the central piers.
Crux arrived on the job with a 35-ton rough-terrain crane to suspend a Crux-designed drill platform, and 28-ton boom truck to suspend a man basket that would ferry equipment and personnel to the drilling platform. At each of the 3 borehole locations, the drilling platform was lowered to the proper elevation and the front of the platform was anchored to the pier. Water-tight rubber sheeting was fitted to the borehole collar to capture drill cuttings for later disposal.
Due to the high profile and environmentally sensitive nature of the project, drill cuttings had to be contained and disposed of offsite. Additionally, Crux was restricted to working during a six-hour window between morning and evening rush hours. Equipment had to be mobilized from, and de-mobilized to, the staging yard each day.
Crane support was used to suspend a custom drill platform at each of the boring locations.
