Thanks for your informative reply.  We do realize that there is "settling"
of structures that would produce cracks, etc.  However, the mine was dormant
for several years and development pursued.  Some even suggest that there
were some back-alley deals made in the what was believed to be a period when
the mine was no longer in use.  Evidence of large cracks, pictures falling,
wells going dry, ....and most influential is a letter from the State Fires
Marshall's office declaring that it is their opinion that the blasting
causes "harm to life and property".  Pretty damaging.

So, we are attacking this at all angles.  The monitoring suggestions you
have will be a benefit to us all. Thanks.

Patrick Wilber

----- Original Message -----
From: "Doug Crice" 
To: 
Sent: Wednesday, July 25, 2001 12:52 PM
Subject: Re: Hello


> There is a special class of seismographs used for "blast monitoring"
> manufactured by Geosonics http://www.geosonics.com , Instantel
> http://www.instantel.com/ , Vibratech and Thomas Instruments
> http://www.vibration.com/index.htm
>
> These instruments use geophones as the basic sensor, monitored
> continuously electronically, and they automatically digitize and save
> any data with a vibration event.  They are about the size of a brick,
> and connect to a laptop.  Software provided by the companies analyzes
> the data for peak particle velocity, spectra, and of course time of
> occurance.
>
> The basic units cost a few thousand dollars, and they can be rented for
> some fraction of the cost.  While it is possible to construct your own
> device to measure these vibrations, it is highly unlikely that the data
> would stand up in court.  Whether you could rent one and put together a
> credible case is also unlikely, since you would be testifying against
> experts. Some of the companies listed above provide the service.
>
> If you really want to attack this problem, the surest approach is to
> hire your own consultant, preferably one smarter and more prestigious
> than the one used by the mining company.  The mining company consultant
> may or may not be right. I should caution you also that a lot of blast
> damage is imaginary.  Cracks appear in houses and sidwalks for a variety
> of reasons and they always get blamed on blasting when there is some in
> the area.
>
> > wildboar wrote:
> >
> > Dear Folks,
> >
> > I am new to this site and my knowledge of its contents is limited.
> > The reason I am interested is that our community lives near a mine
> > that blasts to recover product.  The land use has changed considerably
> > over the last 10 years (from agricultural to
> > ag-residential/residential/commercial) and we are experiencing damage
> > due to the blasts.
> >
> > The "governing" authority for mines is the State Fire Marshall...and
> > the laws governing mining are full of loop holes at best.  The
> > immediate problem is that the mine self-monitors their blasting
> > activities through a subcontractor.  First, many in the community do
> > not believe that the mine always makes aware the State when they are
> > to blast and second, we do not believe the reported results are
> > accurate.
> >
> > What type of equipment could a home owner put in place that could
> > monitor such activities, be defensible in court, and be not to pricey?
> >
> > Thank you for your responses.
> >
> > Sincerely,
> >
> > Patrick Wilber
>
> --
> Doug Crice http://www.georadar.com
> 19623 Via Escuela Drive       phone 408-867-3792
> Saratoga, California  95070  USA fax 408-867-4900
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