The Brooklyn Bridge Park Development Corporation (BBPDC), a subsidiary of the NY Empire State Development Corporation, is responsible for the planning and construction of Brooklyn Bridge Park. The purpose of this Project was to drive 45 foot sheet piles into the existing Pier for future work that would be performed on Pier 1. Phoenix Marine, the General Contractor for Pier 1 was using both a vibratory hammer and hydraulic powered hammer to drive the sheet piles down. Vibration monitoring was necessary for this phase of the project due to the existing subway tunnels which where located within a 75 ft radius of the of the construction activities. The Metropolitan Transportation Authority (MTA) Engineers instructed E2PM to install the geophones at depths of 65 feet and at the (Springline) which is located 55 feet below grade. As required by the Metropolitan Transportation Authority (MTA), the vibration monitors were set at a Peak Particle Velocity (PPV) of 0.7 in/sec.
E2 Project Management LLC (E2PM) was contracted by the Brooklyn Bridge Park Development Corporation (BBPDC) through their construction manager Skanska USA Building Inc (Skanska), to visually observe the installation of two geophones, conduct baseline readings prior to construction activities, and monitor vibrations during the driving of the sheet piles. The vibration monitoring work was performed within the confines of Pier 1 adjacent to the new sheet piling bulkhead. Summary of the services conducted by E2PM for the BBPDC are listed below:
- Observed and approved the installation of two geophones by American Standard Testing at depths of 65 feet and 55 feet.
- Installation of 2 seismographs (Instantel Minimate Plus advanced vibration).
- Conducted a week of baseline vibration monitoring readings.
- Visually observed and monitored the seismographs during the sheet piling activity to make sure vibrations did not exceed the trigger value of 0.7 in/sec.
- Created and implemented a Monitoring Protocol in the event of a triggered event.
- Reported daily to MTA representative of all work activities and readings generated.
- Provided a final report to the MTA and Skanska summarizing the monitoring activities.