Demolition Noise and Vibration Monitoring

Last month one of our High Tech clients came to us with a neat problem. They will be tearing down a warehouse building built in the early 70’s. The problem is that the building shares a party wall and interlocked footings with the adjacent building. On the other side of the party wall, is a computer test lab that needs to run 24/7. Scheduled shut downs require almost a month’s notice to prevent interruptions to test runs.

The goal was to determine how close the demolition could be, before the ground borne vibration and noise would exceed the computer’s operational criteria. A CAT 350 with a ramhoe would complete demolition (i.e. a really big backhoe with a really big jackhammer attached to the end of the hoe arm). Because the building is a single story building slab on grade supported on piles we were able to use the far end of the building to measure the actual ground borne vibration and noise from the unit that would be completing the demolition. The building was approximately 600 by 600 feet square. By completing the tests over 500 feet from the computer room we knew there would be no effects on the computer room equipment.

We measured the vibration in the floor at 10, 20, 40, 50, and 80 feet from the jackhammer as it broke through the slab. The measured levels were compared to the computer equipment operational vibration levels and to ISO (International Standards Organization) building vibration standards. It was determined that they could work within approximately 40 feet of the common wall without requiring the computer lab to be shut down. All in all, a fun project with really big toys.