Standard Practice for (Analytical Procedure) Determining Hydraulic Conductivity of an Unconfined Aquifer by Overdamped Well Response to Instantaneous Change in Head (Slug)

Importancia y uso:

5.1 Assumptions of Solution: 

5.1.1 Drawdown (or mounding) of the water table around the well is negligible.

5.1.2 Flow above the water table can be ignored.

5.1.3 Head losses as the water enters or leaves the well are negligible.

5.1.4 The aquifer is homogeneous and isotropic.

Note 6: Slug and pumping tests implicitly assume a porous medium. Fractured rock and carbonate settings may not provide meaningful data and information.

5.2 Implications of Assumptions: 

5.2.1 The mathematical equations applied ignore inertial effects and assume that the water level returns to the static level in an approximate exponential manner.

5.2.2 The geometric configuration of the well and aquifer are shown in Fig. 1, that is after Fig. 1 of Bouwer and Rice (1).

Note 7: Short term refers to the duration of the slug test.

Note 8: The function of wells in any unconfined setting in a fractured terrain might make the determination of k problematic because the wells might only intersect tributary or subsidiary channels or conduits. The problems determining the k of a channel or conduit notwithstanding, the partial penetration of tributary channels may make a determination of a meaningful number difficult. If plots of k in carbonates and other fractured settings are made and compared, they may show no indication that there are conduits or channels present, except when with the lowest probability one maybe intersected by a borehole and can be verified, such problems are described by Smart (1999) (6). Additional guidance can be found in Guide D5717.

Note 9: The comparison of data from various methods on variable head permeability tests has been documented. Variation in instrumentation, assumptions and calculational methods will lead to differing results (7). Users should be familiar with the assumptions, instrumentation and calculational aspects of the test when evaluating the results (8).

Note 10: The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assure reliable results. Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.

Subcomité:

D18.21

Referida por:

D4043-17, D4104_D4104M-20, D6725_D6725M-16R24E01

Volúmen:

04.09

Número ICS:

07.060 (Geology. Meteorology. Hydrology), 93.020 (Earthworks. Excavations. Foundation construction. Underground works)

Palabras clave:

aquifers; aquifer tests; control wells; groundwater; hydraulic conductivity; slug test;