Easily one of the most misunderstood aspects of
modern american quarry work, blasting is the process of drilling precisely
metered holes into the surface of a rock formation, and then applying
controlled charges to these same holes in order to free a workable
quantity and size of stone for further refinement and processing.
From a historical standpoint, it is not hard to understand where confusion
surrounding the process can arise. In much the same way delapidated
buildings were once toppled through the application of less sophisticated
explosive charges and the crude wrecking balls of a bygone era, the
quarry's of yesteryear were also forced to rely on methods considerably
less advanced than today.
With the advantage of computer-aided research and exhaustive study,
times have certainly changed. Office buildings the world over are
now felled with pin-point precision while fully surrounded by immensely
valuable neighboring structures, and so too has the age of targeted
detonation been applied to quarry blasting.
Now, with the aid of strict government oversight, and the benefit
of unsurpassed seismographic monitoring equipment, members all across
the mining industry spectrum are able to control with ....pin-point
.... precision the exact energy and effect of each and every blast
With such stringent industry regulation, and so many stunning advancements
in blast predictability, why has positive perception of the practice
lagged so far behind?
In part, this can be attributed to a lack of widely circulated information
as to the safety of the process. Aside from industry professionals,
very few people have the time or the inclination to keep themselves
abreast of the laser-like precision that now defines modern blasting.
With by-products of the mining and quarry industry so instrumental
to the vitality of daily american life, this lack of immediate interest
does not extend to the Federal Government, which has devoted considerable
resources to the study of blasting and its effects on neighboring
The results surprise many. Intensely focused research undertaken by
the Department of the Interior as far back as 1971 (Report on Blasting
Vibrations) as to the effects of blasting on neighboring environments
reveals that seismographic activity generated by the process is similar
in scope to that of basic walking, door closing, or the operation
of a clothes washer or dryer.
This level of vibration is commonplace and virtually harmless to human
beings and residential structures, however, there are subtle psychological
differences that do come into play. While a washer or dryer may provide "vibrations" for up to thirty minutes or more, and a blast
only several seconds, the washer or dryer vibration does not come
as a surprise as it is an item we activate with our own hands. This
fundamental difference, or "surprise factor" has long been
suspected as a key cause for the apprehension felt by neighbors of
industries where blasting plays some role in operation.
While blasting itself is an absolutely essential step in the operation
of a quarry, here at T.H Kinsella specifically, we undertake protective
measures far beyond that mandated as the industry norm in the interest
of preserving the full sanctity of the environment that surrounds
How do we do this? Well, to begin, let's start with a basic look at
the process. As a general rule, we utilize at or near 4,400 pounds
of explosives to extract every 9,000 tons of stone. The key component
in these charges is an ammonium nitrate compound, which is actually
a form of fertilizer. This compound has a number of desirable characteristics
suited to its job, but chief among these is that it can be handled
and stored without danger of accidental detonation.
When a blast does become necessary to "unlock" a supply
of stone, the ammonium nitrate compound is doled out in a carefully
measured dose into drill holes prepared in a rock face as described
previously. Each charge is then detonated in precise sequence to ensure
that every ounce of explosive energy is utilized specifically toward
breaking the intended stone and dropping it directly onto the quarry
floor - this is the initial ground vibration that some of our neighbors
feel when we blast. In actuality, this rumble is many small detonations
that go off one after another over a short time frame.
After a few seconds, depending on the distance from our quarry to
the observation point, an interested onlooker may feel and hear an "airwave." This results from small amounts of the blast's
energy naturally escaping into the airspace above. Under most circumstances,
this energy dissipates rapidly into the atmosphere. Under certain
atmospheric conditions some of these airwaves can bounce off of dense
cloud cover and back to the ground, where they may at times be felt
Fortunately, after more than 40 years of careful study by federal,
state, and private agencies, it is now possible to measure with precise
accuracy the effect of blasting in any area, and it is from this data
that proven safety standards have been developed by governmental agencies
to assure the protection of property bordering rock quarries all across
the United States.
Here at T.H. Kinsella, the ground vibrations from blasts in our quarry
are an average of only 1/5 of this mandated limit. Why do we maintain such a significant
margin of safety by staying this far below the standard? Quite simply,
it is a matter of carefully planned Company policy designed to ensure
with certainty that undue stress be alleviated from our neighbors.
Not only are we pleased to embrace a policy of hyper-vigilant and
responsible blast planning, but we proudly monitor and record every
relevant variable for each of our blasts in order to demonstrate our
compliance well in excess of governmental standards.
A neighbor you can depend on, a name you can trust - that's the T.H.
Kinsella tradition at work.