Encia Demolition carried out the detonation of the 65 metre tall Gem Mill chimney in Oldham to make way for a housing development. In order to monitor the ground vibrations caused by the detonation, the company hired a Vibrock V901 seismograph from Ashtead.
The instrument is capable of continuous monitoring and allows the user to set threshold parameters for impulse triggered monitoring, with all results stored internally for subsequent download. It can also be used for unattended monitoring of ground vibration events such as quarrying, demolitions, drilling, rail and traffic vibrations
Rob Tinsley, Safety Manager at Encia Group, explains, “We wanted to monitor the ground vibrations from both the detonation and the impact of the chimney hitting the ground as a precautionary measure. Subsequent analysis of the vibration recording by structural engineers indicated that levels were not a significant issue.
“We found Ashtead Technology Rentals very helpful and they ensured that Encia Demolition’s monitoring team knew how to get the correct measurements. Hiring the instrument had many benefits; it avoided a capital cost and enabled us to use the very latest equipment.”
The Gem Mill chimney was built in 1901 in the Chadderton district of Oldham and took just a matter of seconds to crumble to the ground following the explosion.
Ashtead Technology Rentals’ General Manager James Carlyle added, “This is a good example demonstrating the advantages of hire over purchase. The equipment is always delivered fully-calibrated and clients are given a concise run-through on how to use the instrument to its maximum capacity.”