Written by Graeme Murphy – Product Manager TechRentals and Paul Brooker – Consultant, TechRentals June 2012
There are occasions when your construction project will be adjacent to another building that is very vulnerable to damage or is subject to special protection. Historic buildings are one category that may be damaged by ground vibration due to construction work and there are defined limits as to what is allowable.
In these cases monitoring instrumentation will provide you with an accurate knowledge at any time of what is being caused by your site activities. It will also provide you with a record of ground vibration that may be very important in proving that you took reasonable steps to minimise damage. If damage does occur it is likely to be expensive and difficult to repair which is a liability that would be prudent to avoid.
The appropriate instrumentation is a ground vibration logger which is placed on the nearest property boundary. Site photographs of the logger installation and site can be date and GPS location stamped with many mobile phone cameras as additional evidence of due care.
Apart from logging the ground vibrations the vibration logger can have an alarm warning light for construction workers. The alarm is set to the maximum allowable vibration level. Generally for historic buildings the maximum is a Peak Particle Velocity (PPV) of 5mm/sec with a more generous limit for modern buildings of 10mm/s PPV. Setting to a lower threshold will give you a level of confidence and provide a guide to site workers.