PSN-L Email List Message

Subject: Re: Hello
From: Doug Crice dcrice@............
Date: Wed, 25 Jul 2001 09:52:46 -0700

There is a special class of seismographs used for "blast monitoring"
manufactured by Geosonics , Instantel , Vibratech and Thomas Instruments

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

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
19623 Via Escuela Drive		      phone 408-867-3792
Saratoga, California  95070  USA	fax 408-867-4900

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Larry Cochrane <cochrane@..............>