Westlake & Mercer Automated Monitoring

Monitoring

The area east of Westlake and north of Mercer Street in downtown Seattle, was planned for restoration by adding parks, a trolley system, and clean up of old, petroleum contaminated sites.
Hazco Environmental subcontracted to URS to implement clean up of the area which required excavation and replacement of soil within a sheet pile wall adjacent to three structures of histor

SubTerra’s Scope of Work

SubTerra’s scope included: Technical Review of Potential Vibration Related Impacts: This work involved modeling the anticipated source vibration levels, their attenuation, and the possible range in vibration levels at the adjacent structure(s). SubTerra utilized vibration waveforms that were available from the literature, vibration waveforms previously collected for different vibratory hammers, and off-site monitoring of actual construction methods proposed by the Contractor along with industry accepted attenuation equations.

Initial Pre-Construction Survey: The preconstruction survey involved shooting digital video of the structure and surround, digitalstill photography of the structure, installing vibrating wire displacement gages and crack meters and completing a detailed description of the external and internal condition.

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Automated Monitoring

2006

Project Initiated

820ft

Surface Area

300

individual monitoring stations

Project Planning

Project Planning Input: Recommendations were developed for project procedures (equipment, monitoring, etc.) and maximum allowable vibration levels for the three historic structures.

Monitoring During Construction: An automated vibration monitoring system was installed including four seismographs reporting via the internet with threshold and limit value alerts provided via cell phone and e-mail.