“What’s that Vibration?”

With Brighton Mills demolition complete, construction will begin in the coming weeks at 400 Western Ave on the Charlesview Redevelopment.  The construction activity on the site will involve the use of equipment which will likely produce perceptible vibration, especially during the months of October and November.  Information is provided below on the effects of this vibration on neighboring structures, and two public meetings will be held in early October to allow the construction team to hear any questions or concerns from community members.

  • Wednesday, 10/12, 10:30am, McNamara House, 210 Everett St
  • Wednesday, 10/12, 6:30pm, Brighton Resource Center, 367 Western Ave

The Community Builders, the developer of the Charlesview Redevelopment, has retained the services of Rick Groll, Industrial Seismologist, to examine the site, geotechnical report, and adjacent structures for the project.  A few neighbors to the construction site have already met Mr. Groll.  For the benefit of those whom have not yet met him, Mr. Groll has provided a description of how vibration is both calculated and assessed when determining the need for building surveys, summarized below:

Research in the field of industrial seismology has determined that the best descriptor of damage potential to building materials from ground vibration is related to the speed at which a material is agitated.  The quantity most commonly referenced in damage studies is “peak particle velocity” and is expressed in units of inches per second (ips). The recommended limits for peak particle velocity differ by building construction material, such as concrete, masonry or wood. The most sensitive common construction material to vibration is plaster on lath.  Construction materials are more sensitive to steady state vibration than impulsive vibration, therefore, the damage thresholds established for steady state vibrations are lower than those established for impulsive vibrations  The level of ground vibration decreases the further you are from the source—if the receiver is double the distance away, they observe a three-fold decrease in the level of vibration.  

The Charlesview geotechnical report indicates that the piling activities at this site will exclusively be “sonic” (vibratory sheet driving) and the material adjacent to Western Ave is partially composed of dense gravel.  

The owners of homes and other buildings which could potentially be exposed to a level of 0.12 inch per second, which is the most conservative ground vibration limit designed to protect structures, were offered an inspection to document existing interior and exterior building conditions.   The building survey records general property conditions and specific structural defects in video format.  

Based on Mr. Groll’s review and industry threshold criteria to prevent damage and distance between the new pilings and surrounding structures, a radius to perform building surveys was established.  The established radius for building surveys is structures within 100’ of the anticipated sheet piling activities. 

Neighbors outside of the 100’ radius are outside the radius in which any level of vibration approaching any damage threshold criteria should be expected.  However, some occupants will feel the vibration for much of the duration of sheet pile driving. 

NOTE: Even very low levels of vibration (under 0.10 inch per second) can cause objects like glasses, vases and pictures to “skate” across tables and shelves.  Neighbors may wish to relocate fragile items to a safe place during October until mid-November.  These occupants should be aware that while they may experience the vibration, the vibration will not result in structural damage to the buildings they occupy.

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