Aquifer testing.
Sounds interesting but what is an aquifer test. Aquifer testing
is a planned
procedure where a well is pumped and the response to the pumping is
measured by monitoring the water level in both the pumped well and
adjacent wells as the well is pumped and after it is shut down.
The water level data
is then analyzed to establish aquifer parameters such as
transmissivity, coefficient of storage and hydraulic
conductivity. Properly run and analyzed, aquifer tests can
provide a wealth of
information for use in managing your groundwater resource.
OAI presents this collection of
photos with explanations of what you see. Begining in the
photo at the top right and moving counter clockwise:
Top Right: This photo was made during a 48-hour constant rate
test for a Choctaw County water system. The test utilized an
adjacent
private well as an observation well and a data logger, held by my son
Sam, to collect water levels as the test was run. Of interest in
the photo is the white
PVC piping sticking up behind and to the left of Sam's head. The
aquifer being tested had enough artesian pressure
to cause the water level in the private supply well to rise ~ 8 feet above
ground. The PVC column was added to the exisiting well to account
for this pressure. A second "flowing well" was also monitored
during the test. This aquifer test supported the development of a
2-well single aquifer wellfield at this location. Using the private well
saved
the system the expense of an observation well for the test and, more
importantly, eliminated an artificial penetration of the overlying clay
that protects the aquifer from contamination from surface sources.
Top Left: Ahh the smell of fresh groundwater in the
morning. This
is a photo of a 1,500 gpm discharge for a south Mobile County
system. The photo was taken toward the end of the required 24/6
test.
In a 24/6 test, the well is pumped at design capacity for 24 hours
after drawdown in the production well stabilizes then it is cranked up
to 150% of design
capacity and pumped unitl it stabilizes at the rate for an additional 6
hours. This well was permitted at the 1,000 gpm rate.
Middle Left: This was a neat test in that it used multiple
observation wells screened in different aquifers. The test was
run to assist in permiting a south Mobile County system's new
well. The two observation wells included one, seen by the card
table, screened in a shallow aquifer and
the other, seen just above and to the left of the thermos, screened in
the aquifer tapped by the production well. Both observation wells
were monitored
with data loggers and electric tapes. Data from the test was used
to evaluate the hydraulic conductivity of the confining unit separating
the two aquifers. Aproximately 48 hours of testing was completed
at this site. That's Dan back in the shade (it gets hot in Mobile
County) with his nephew Michael who assisted on this test. Michael is now a PE in Florida.
Lower Left: This is a photo of a "tight" well being
developed. Our son Daniel is seen in the photo as the well is
blowing. This deep well was drilled
based on hydrogeology worked
up by OAI that identified a deep untested aquifer in the area.
The exploratory bore for this project was drilled at the time of the
terrosit attacks of September 11,
2001. The aquifer tapped by the test well is the deepest
freshwater aquifer in
Mobile County. Daniel, gradutes from Troy in May 2008 and will enter the Army's nursing program.
Lower Right: A co-hort snapped this shot of Dan getting a
little
shut-eye after ~30 hours of testing. OAI runs data loggers on all
our tests and we collect critical measurements using electric tapes as
back-up to the data loggers in the event they fail. We know the
importance of obtaining quality data and don't want to miss any of
it. OAI has completed aquifer tests up to 10 days in length.
Middle Right: This is a photo of a 1,245 gpm test for a Baldwin
County system whose new well was drilled based on OAI's subsurface
mapping and siting recommendation.
Over 1.4 million gallons of water were produced during this test.
An intersting thing noted on this test was a slight increase in
water level in the observation well as a locomotive passed typical of
confined aquifers. The observation well
installed during the permitting process is now
equipped
with a data logger to continuously track water level over
time. OAI received a grant from the Mobile Bay National
Estuary Program to monitor water levels in four obervation
wells monitoing aquifers tapped by 13 public water supply wells.
Water level monitoring is a critical but often overlooked part of a
system's management plan. Call today to learn more about the
importance of water level monitoring program for your wells.

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