Repairs to Seattle Public Utilities SODO Substation

Construction of a new six-story building adjacent to Seattle Public Utility’s Massachusetts Substation required management of Construction Vibrations to protect sensitive power station equipment that would be subject to potentially damaging vibrations SubTerra was retained by SODO Builders to evaluate potential impacts, evaluate the potential contribution of pre-drilling to minimize vibration levels and remotely monitor vibrations during construction.

SODO Vibrations Monitoring

SubTerra, Inc. was contracted as the vibration monitoring specialist for the SODO Builders project, 1531 Utah Avenue South.  Construction of the six-story building began with the installation of over two hundred 18- and 24-inch diameter, 110-foot long steel piles.  Concerns were raised when it was discovered that sensitive relays that control the power to half of downtown Seattle were housed in a building only 20 feet away from the nearest pile to be installed.

Automated Monitoring with the Instantel MiniMate Plus

SubTerra, used eight Minimate Plus seismographs to create attenuation models based off of six test piles and determined that mitigation was  necessary.  By carefully studying the relationship between distance, depth and peak particle velocity, SubTerra was able to recommend pre-drilling piles to a depth of 30 feet within a 40-foot radius of the sensitive equipment.  The recommendation was successful and SODO Builders was able to com-plete the project without interruption to the city’s power supply.

SubTerra’s SubTWarden Vibration Monitoring System

The SubTWarden remote seismic monitoring stations combine an Instantel Minimate Plus seismograph, dual strobe remote alarm, wireless modems and 12-volt DC power inside of a rugged weather-proof NEMA 4 enclosure.  Wireless modems allow the Minimate Plus to upload its data to our secure website and send auto- matic alerts to Project Managers, Superintendents and Inspectors via email or text message.