Wilson Ihrig & Associates, Construction Practices to Address Construction Vibration and Potential Effects on Historic Buildings Adjacent to Transportation Projects, September, 2012
[See page 5-247 for the original comment] The National Highway Cooperative Research Program has funded preparation of a guidance document Construction Practices to Address Construction Vibration and Potential Effects on Historic Buildings Adjacent to Transportation Projects (Wilson Ihrig, 2012). This document outlines a recommended approach for addressing and mitigating potential vibration impacts to historic structures. The first four of these measures were conducted as part of the Draft EIR in Impact 4.J-2, while the following three measures were identified as part of the pre-construction assessment identified in Mitigation Measure 4.J-2b. The remaining measures (below) are added as elements to be considered in the Pre-construction assessment identified in Mitigation Measure 4.J-2b of the Draft EIR. Mitigation Measure 4.J-2b is revised to read as follows.
Mitigation Measure 4.J-2b: Pre-Construction Assessment to Minimize Structural Pile-Driving Vibration Impacts on Adjacent Historic Buildings and Structures and Vibration Monitoring. Any development within 85 feet of the Roundhouse that would require pile driving or other construction techniques that could result in vibrations of 0.25 in/sec shall engage a qualified geotechnical engineer subject to City approval to conduct a pre-construction assessment of existing subsurface conditions and the structural integrity of the nearby historic structures subject to pile-driving or other vibration-inducing activity before a building permit is issued to demonstrate that the proposed construction activities would not result in vibration-induced damage to the Roundhouse building.
If recommended by the pre-construction assessment, groundborne vibration monitoring of nearby historic structures shall be required. Such methods and technologies shall be based on the specific conditions at the construction site such as, but not limited to, the pre-construction surveying of potentially affected historic structures and underpinning of foundations of potentially affected structures, as necessary. The pre-construction assessment shall include a monitoring program to detect ground settlement or lateral movement of structures in the vicinity of pile-driving activities. Monitoring shall be maintained while construction occurs within 85 feet of historic structures, and results shall be submitted to the City Engineer. In the event of unacceptable ground with the potential to cause structural damage movement (in excess of 0.25 in/sec PPV at historic structures), as determined by the City Engineer, all impact work shall cease until corrective measures (e.g., installation of vibration wave barriers) are implemented to reduce ground movement to below 0.25 inches PPV.
In addition, the following measure shall be implemented:
- Evaluate and implement feasible measures for reducing vibration, such as alternative pile driving methods (e.g., cast‐ in‐drilled‐hole