Mines doing all they can: EPA
Wednesday, 9th January, 2013
Work underway to reduce shock firings
By Andrew Robertson
CBH Resources will try to reduce the duration of its underground firings at the Rasp Mine in response to complaints.
The commitment comes as two representatives from the Environmental Protection Authority (EPA) met with mine management yesterday to discuss the firing and other EPA-related issues.
Speaking after the meeting, Darren Wallett, head of the EPA’s Griffith Unit, said that the EPA was continually working with CBH to try and reduce the impact the firing has on residents.
The company has never exceeded its licence conditions covering vibration levels but since the resumption of mining at Rasp last year the EPA and CBH have received numerous complaints.
The most recent followed a firing on the 8 level on Monday evening.
“The blasting the other night, and we were on the road when the reading came through, but my understanding is it was still within the licence limits,” Mr Wallett said.
“But what we’re working with the mine to achieve is to lower the vibrations limits to a point where it doesn’t disturb amenity.
“The noise, I think, would have been a little bit higher than they would have liked but particularly the duration ... so what we spoke about today is they’re going to try a number of different measures to reduce the impact.
“They’re going to try and reduce the duration of the blasts and they’re still going to aim ... to reduce those vibration impacts.”
Under CBH’s licence conditions, vibration readings are not to exceed 5 millimetres per second for 90 per cent of firings, and 10 millimetres per second for the other 10 per cent.
But Wallett explained that the company aimed to achieve a much lower vibration level.
“We’ve got an agreement with the mine that they aim for their blasts to be around the three milimetres per second of vibration, and that’s what the mine actually aims at blasting.
“Every blast they do they have a formula...so they aim to achieve well below the licence limit ... but on occasions, for no apparent reason, one blast will have a higher vibration than another that may have a lesser explosive ...”
The company monitors every firing using three fixed monitors on its lease, two on the western side and one on the eastern side, plus a roving monitor.
“In terms of the amenity what we’re doing with the mine is we’re heavily monitoring all of their blasts they provide us with frequent reports.
“Ultimately our aim is we don’t want people complaining about it. That’s certainly where the EPA is.
“We’ll just continue to work with them until there’s no amenity impact.”
Mr Wallett said he and his colleague met with a number of licence holders yesterday, including all three mining companies, plus a number of residents.
“We’ve seen three or four complainants including one for the blasting.
“We’ve got a number of agreements and programs with the other mines to just do bits and pieces of work that need to be done but not a significant environmental issue.
“We go over this same ground all of the time.”