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GROUNDWATER:
HERE YOU
Groundwater is often called a “vast-hidden
resource” because except for a few rare cases, like Old Faithful and
Mammoth Caves, groundwater is rarely seen and seldom recognized.
Yet groundwater makes up about 20 percent of all water
consumption in this country including over 40 percent of water used for
domestic purposes, over 40 percent of water used for agricultural
purposes, and over 15 percent of water used for industrial purposes.
We are frequently asked to determine if there is a
reliable groundwater supply for a development.
Even though we have been in the groundwater business for over 30
years, it never ceases to amaze me that on one side of a road the answer
to the question can be “yes” and on the other side it can be “no.”
Since groundwater is a hidden resource, frequently it’s just not
apparent what the answer will be unless you do the appropriate testing.
The testing can be as simple as reviewing all water
well logs in the area and local geologic and groundwater reports.
If available, this information allows you to develop a
three-dimensional picture of the subsurface geology and groundwater
conditions. This may be enough
information to rule out the possibility of a groundwater supply problem;
however, it is not necessarily enough to conclude there is a reliable
groundwater supply.
“Pump tests” have been used for decades at
development sites to evaluate the potential for groundwater production.
A pump test is simple: you drill a well, pump water from the well
at a constant rate, and monitor the water level in the well during the
process. Pump tests are
conducted by water well drillers who typically run the test for several
hours. A pump test tells the
well driller what pumping rate can be used in the well without running the
well dry.
Groundwater specialists run more sophisticated
versions of these tests called “aquifer tests.”
Aquifer tests may be run for one or two days (or longer) and
typically involve monitoring water levels in the pumping well and in other
nearby wells called “observation wells.”
In addition to determining the optimum pumping rate for the well,
aquifer tests provide valuable information on the aquifer including
potential for well interference problems (My well is okay, but what
happens when my 10 neighbors start pumping?), aquifer limitations
(aquifers have boundaries and you may be close to one), connections
between water bearing units (Could that landfill half a mile away affect
my groundwater supply?), and impacts on surface water bodies (sometimes,
groundwater pumping can lead to streams drying up).
Regardless of whether you are seeking a domestic, industrial, agricultural, or municipal groundwater supply, the increased knowledge gained from running the more sophisticated aquifer test reduces the potential for unpleasant surprises with your hidden resource. We can show you how an aquifer test will keep you out of trouble by really understanding your hidden resource.
