Naked Science Forum
Non Life Sciences => Geology, Palaeontology & Archaeology => Topic started by: Karen W. on 13/10/2009 09:56:26
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We have two rock quarries within a mile of my house.. In the same area.. Today they started firing and blasting away at the large earth covered rocks..
My windows were shaking and the whole house shaking like an earthquake under me. The rumble and the blasts were multiple dynamite charges, that seemed spaced out as if going off in a large line headed at my home...
Is it legal for them to be blasting so close to our homes? Much more and I would have had property damage....!
Anyway is it common to blast so close to peoples home and many many were closer then I?
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Your in California so I doubt that there would be any danger of being endangered. The state has the most strict laws concerning environmental damage in the US.
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You should check with the county and see what, if any, regulations they have regarding blasting. Also check with the local university and/or California Geologic Society to see if they have any seismic record of the blasts.
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I will check with Humboldt State University.. They have a huge knowledge base on seismic activity for this area..
I just know that if they keep blasting some one is going to start paying me for broken windows soon!
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I suspect that the quarries might be on a different scale to the ones I deal with her in the UK (the biggest having a capacity of 1Mt per year), but part of my job is to deal with complaints relating to blasting in hard rock sites.
The chances are the windows were rattling due to "Air Over Pressure" - this is the shockwave from the blast in the air (also known as concussion). Whilst highly disturbing, it is unlikely to cause structural damage to a building.
Structural damage is caused by very high levels of ground vibration - I will try and dig out some figures, but from a mile away it is highly unlikely to be an issue. I deal with sites where the separation between properties and quarries is as little as 200m and blasting can be carried out within quite tight limits.
Blasting techniques have improved (at least in the UK) over recent years, with significant efforts made to reduce ground vibration, through millisecond delays and "decking" explosives and moving on from ammonium nitrate & fuel oil (ANFO) as an explosive.
The other possibility is that if they are opening a new phase of working then they have had to carry out "pre-split" blasts. This is where an area is stripped of soil and overburden , drilled and fired. As the shot is fired right on the surface and the rock is confined by the surrounding rock, they tend to be more violent than a similar charge of explosives on a normal production shot on a quarry bench. Air over pressure tends to be a lot worse.
If this is a problem, it might be worth contacting the quarry operator - certainly in the UK they tend to want to be good neighbours (within reason) because if they are not they might not get planning permsion for extensions or new sites!
This website is pretty good for explaining in plain english all about blasting. http://www.goodquarry.com/article.aspx?id=16&navid=1 (http://www.goodquarry.com/article.aspx?id=16&navid=1)
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My windows were shaking and the whole house shaking like an earthquake under me.
Apparently a fumble can cause a rumble too, lol.
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lol..Well I have lost another window but I must not be the only one!!! Someone called in some kind of official quarry inspectors for California.. They were at the site for a couple days doing inspections and the blasting and really bad shaking has ceased.... I am not sure yet the outcome and results of safety inspections..