Paynter Branch Mining
“My husband works for the mines, but they can’t tear up my house,” Barbara Jeffries of Cyclone, interview August 2000.
Like Tri-County in Dingess, this is a small mine with small blasts. Yet it was frequently within 1,500 feet of the community and caused a lot of problems. The mine stretched for about a mile, its perimeter following Route 10 through Cyclone, never more than 2,000 feet away up on the mountain.
The complaints about blasting began to come into DEP towards the end of 1997. By 1999 though, people were tired of complaining, since the problems didn’t seem to be easing. Still they filed a dozen between March 1999 and February 2000.
“Blasting on 6-24-99 at 4:15 p.m. was extremely loud and shook her house so hard that it scared her visiting grandson who was inside of the house at the time of the blast,” wrote the DEP inspector about a complaint from Barbara Jeffries. Her neighbor, David Robertson, complained on March 23, 1999: “Blasting from Paynter Branch Mining has been shaking the complainant’s residence and on 3-22-99 at approximately 4 p.m. a blast occurred that ‘shook’ the dwelling hard and caused items to fall off of shelves in the den of the dwelling.”
Dust from the mines was a problem, partly because the fairly large community was so close to the mine. Though the mine is not visible from the road, its location on the edge of the mountain was similar to the Dal-Tex mine in Blair. This allowed the dust to float out over the houses.
The blast on Aug. 25, 1999 was particularly dusty and generated two complaints. David Robertson took photos that clearly showed the dust. The DEP inspector wrote: “Paynter Branch Mining Inc. has agreed to wash Mr. Robertson’s house as he requested after mining has progressed away from the location of the house.” The mine agreed to wash other houses as well. Yet more than a year later, no houses have been washed.
Unfortunately, the one person who was keeping a log of the blasts threw it out because the mining was ending and she saw no use for her records. This is the one mine, where the complaints are based solely on complaints filed with DEP.
However, this mine was one of two that regularly seismographed the blasts. It did seem that the machine was close to one group of homes and not to another. The blasts were loud enough to trigger the seismograph 30 of the 35 times that the closest structures were houses 57, 88 or 91 (all near the Jeffries and Roberts). It did not trigger when the blast was closest to house 152.
Interestingly, all but five of the 35 air blasts recorded were over 115dB. Several DEP inspectors have said they found complaints start coming in when air blasts are over 115 dB.
The DEP inspector was quite thorough. After one of the first complaints in late 1997, he wrote a letter with his findings. This time, he found that the mine was using the wrong closest structure. The log said it was 1,800 feet away when it was actually only 1,400 feet. This reduced the allowable amount of explosive per delay from 1,070 pounds per delay to 648 pounds per delay. Then the blaster timed the shot incorrectly, causing 1,200 pounds to detonate instead of the 648 pounds.
WHAT THE DATA SHOWS
We reviewed 103 blasts, of which nine generated complaints to DEP. Without a more complete list of problem blasts, it is somewhat difficult to determine what is different about the blasts that did cause problems. However, the presence of seismograph data is helpful.
Location of the blast appeared to be one factor. The complaints only came when the blasts were in just seven of the 80 grids where blasting took place. The blasting logs require mines to include the grid numbers. Grids look like a graph paper and the letters and numbers generally start in the top corner at the left, just like in a spreadsheet. So the grid will read J-19 or NN-46. All the grids where bothersome blasts occurred were towards the center of the mine: J-19 through QQ-41.
As noted above, the air blasts were particularly high here. The highest (132dB) occurred on the day that Barbara Jeffries said the house shook so much it scared her grandson.
Interestingly, the majority of blasts that caused complaints were detonated in the direction of the nearest protected structure, even though DEP recommends detonating away from homes in order to reduce vibration.
The data on the frequencies of the blasts is also enlightening. The Bureau of Mines has found that frequencies between 4 and 11 Hz can magnify the shaking feelings if the house is responsive to the frequency of the blast. Most of the frequencies from these blasts were between 7 Hz and 11 Hz.
Continue to in-depth analyses of blasting problems in nine communities:
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