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KIRTLAND AIR FORCE BASE ALBUQUERQUE, NEW MEXICO ...

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APPENDIX B<br />

A second method consists of placing a temporary well with a 5-ft screen into the cleaned out boring,<br />

pulling the drilling casing back to expose the screen and allow the formation to collapse around the<br />

screen (or placing a sand/gravel pack around the screen if the formation does not collapse), and<br />

performing the appropriate hydraulic conductivity test in the well, as described for the first method.<br />

Again, the test should be conducted until the water level stabilizes or for a minimum of 20 minutes. This<br />

method allows for testing a larger section of the formation and results in more reliable hydraulic<br />

conductivity estimates.<br />

A variation of the falling head test is the constant head test, in which water is added to the boring at a<br />

measured rate sufficient to maintain the water level in the boring at a constant height above the static<br />

water level in the boring. The discharge rate into the boring or well is measured once a stable elevated<br />

level has been achieved for a period of time, usually 10 to 20 minutes, and the hydraulic conductivity<br />

calculated from this. After the test is over, additional information can be gathered by measuring the rate<br />

of the drop in water level in the boring (for saturated formations). A limitation of the test is that foreign<br />

water is introduced into the formation which must be removed from the well area by natural or artificial<br />

means before a representative groundwater sample is obtained. This method of testing may be use in<br />

both saturated and unsaturated formations and is the only hydraulic conductivity test (except for Packer<br />

Tests in some cases) that can be performed in unsaturated formations. This test method may be<br />

necessary for highly permeable materials, in which the water level recovers rapidly.<br />

Slug Testing in Wells<br />

Hydraulic conductivity tests can also be performed in completed wells. Prior to testing, the well should<br />

be thoroughly developed and water levels allowed to stabilize in order to obtain accurate results. After<br />

the water level has stabilized, it should be raised or lowered and the rate of recovery measured as<br />

described for tests in boreholes. An advantage of using a solid cylinder of known volume to change the<br />

water level is that no water is removed or added to the monitoring well. This eliminates the need to<br />

dispose of contaminated water. Constant head tests can also be performed in wells, using the same<br />

procedures as described for constant head tests in borings.<br />

The following data should be obtained when performing an in-situ hydraulic conductivity test in addition<br />

to the static water level and all time and water level measurements. This data should be recorded in a<br />

field logbook or on the data sheet depicted in Figure B5.7-1.<br />

Ground elevation<br />

Reference elevation<br />

Depth of test run<br />

Casing diameter<br />

Length of uncased borehole<br />

Identification of equipment used<br />

Well pipe and screen diameter and length<br />

Screen slot size<br />

Kirtland AFB<br />

SOPs for Field Investigations B-140 April 2004

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