Mingo Logan (Arch Coal)
Deborah Hatfield has taken her most precious photos and knick knacks off her walls. Too many times, she says, things have fallen off and broken when the mine behind her home let off a blast. One morning in September of 1999, the house shuddered and pictures shook. Quickly she called the DEP Logan office. By now, she knows the number by heart.
The blasting is actually just the most recent insult from the mining. For five years, the Hatfields have suffered though one of the worst cases of subsidence from the long- wall mining under the Pie area of Pigeon Creek. The cement steps on the porch shifted, their lawn sank, numerous cracks formed and their well went dry. So it’s hard to tell which damage is coming from blasting. It certainly is annoying, though.
Patricia Bragg, the lead plaintiff on the valley fill lawsuit was dragged out of her quiet life as a housewife six years ago when her next-door-neighbor’s well went dry just as she moved into her new house. Trish was able to get replacement wells for a couple dozen in the community. She avoided subsidence damage, and life with the mine was not overly eventful for a couple of years. Then the blasting began. Her house is older, and the roof has begun leaking. Whether the blasting has caused cracks and shifting is yet undetermined. Just recently, though, the mine offered her (as required) a subsidence survey. That way they would know how the house appeared before long wall mining began underneath.
Over Labor Day weekend, there was not one, but two washouts from the sediment ponds for the valley fill up Nighway Branch behind the Braggs and Hatfields. DEP determined that the mine had not cleaned the sediment and mud out of the ponds, and the muddy water washing off the unfinished fill had no where to go except down Nighway Branch. Bragg’s home was spared, but the water went up to the second step of her neighbor’s porch (the same one who lost the water six years ago).
It’s getting hard to tell where the damage is going to come from next in this little community.
We examined 154 blasts, of which 51 caused problems.
When we went to look at the logs, the mine official gave use three sets of files for three different permits. We found that the mine sometimes blasted twice or even, a couple of times, three times within two or three minutes. The mine official said he did not know that was happening. Every one of the 12 occasions that we found resulted in a problem blast.
The Bragg house is about 500 feet southwest of a house that was used as the closest protected structure in at least half of the blasts. This is another mine that shoots a large amount per delay. Ninety of the 154 blasts were more than 600 pounds per delay. Of those, 35 caused problems. A few of the non-problem blasts were about 5,000 feet from the nearest protected structure.
But what seemed to make the most difference was timing. DEP maintains changing timing can make a significant difference. In fact, it is the one change DEP has experimented with. All but seven of those that caused problems used only two different delays. They varied: 100 ms and 42 ms, 100 ms and 9 ms, or 42 ms and 9 ms (all with 500 ms. down holes). On the other hand, 30 of the 55 larger blasts that did not cause problems had more delays, generally 9ms 42 ms and 100 ms, with 500 ms down holes.
The seismograph triggered on 16 of the problem blasts. The frequencies of 12 blasts were within the 4 Hz to 11 Hz range can amplify the shaking of a house. Only two air blasts exceeded 115 dB, however. This mine only had a couple of binder shots with one causing a problem.
Continue to in-depth analyses of blasting problems in nine communities:
COWEN CYCLONE DINGESS FOSTER KIAH CREEK KISTLER AMEAGLE/COLCORD/DOROTHY PIE VARNEY HOME