KIRTLAND AIR FORCE BASE ALBUQUERQUE, NEW MEXICO ...

APPENDIX B
As much information as possible should be collected and evaluated before running an aquifer test. This
includes groundwater flow direction, hydraulic gradients, regional water level trend, the existence of
other pumping wells in the vicinity of the test area, the expected groundwater quality of the discharge
water, and the expected specific capacity of the pumping well.
Pumping equipment should conform to the size of the well. Drilling logs, data about well construction,
and performance characteristics of the other wells in the area should be examined if available.
Transmissivities may be estimated from the boring logs and preliminary testing. Any number of
observation wells may be used. The number chosen depends on maintaining a balance between cost and
the need to obtain the maximum amount of the accurate and reliable data.
The spacing of the observation wells should be determined based on expected drawdown conditions and
preliminary pumping results. Generally, two observation wells are sufficient to achieve desired
objectives. However, further definition of consistency requires up to four observation wells. In addition,
under high transmissivity conditions, additional wells at greater distances will provide good
representative average values. On the other hand, areas with low transmissivity might not provide
sufficient response under low pumping rates to necessitate any observation wells. Under this situation,
single well tests are used. The ultimate decision on the number of wells required for adequate pump tests
is a function of expected conditions, project objectives, and cost.
If a pumping well does not fully penetrate an unconfined aquifer (any well open or screened through at
least 85 percent of the saturated thickness of the aquifer may be considered as fully penetrating), the
observation wells should be located at a minimum distance equal to 1-1/2 to 2 times the aquifer thickness
from a partially penetrating pumping well to overcome distortions of flow pattern due to partial
penetration.
If testing a confined aquifer which is not thick, the pumping well should be screened for the entire
thickness of the aquifer. For an artesian aquifer the water level in the pumping well should not be
allowed to fall below the bottom of the upper confining bed during the aquifer test.
Preparation for Testing
For a few days before starting an aquifer test, water levels in the pumping well and observation wells
should be measured at about the same time each day to determine whether there is a measurable trend in
groundwater levels. If such a trend is apparent, a curve of the change in depth versus time should be
prepared and used to correct the water levels read during the test.
Pumping wells should undergo preliminary pumping prior to the actual test. This will enable fines to be
flushed from the formation and a steady flow rate to be established. The preliminary pumping should
determine the maximum drawdown in the well and establish the pumping rate for the later test. Step
testing should be performed to determine the proper pumping rate for the long-duration pumping test to
follow. The aquifer should then be given time to recover before the pumping test is begun.
Barometric changes may affect water levels in wells, particularly in confined aquifers. An increase in
barometric pressure may cause a decrease in the water level. Any change in barometric pressure during
the test should be recorded, in order to correct the water level measurements taken during the pumping
test, if required.
A record should be maintained in the field log book of the times of pumping and discharge of other
pumping wells in the area, if their radii of influence intersect the cone of depression of the pumping well.
Kirtland AFB
SOPs for Field Investigations B-142 April 2004