Estimation of hydraulic conductivity in large-diameter, hand-dug wells using slug-test methods

Abstract To demonstrate the viability of using slug-test-analysis techniques to interpret recovery data in large-diameter, hand-dug wells, 37 wells representing a range of hydraulic conductivity and located in unconfined and weathered chalk and marl and confined alluvium in North-Central Texas were tested. Recovery data were analyzed by means of a numerical model, two semiempirical methods developed especially for interpreting recovery data from large-diameter hand-dug wells, and different slug-test-analysis methods that have different shape factors describing well geometry. Most hydraulic-conductivity values estimated by slug-test methods are within an order of magnitude of values that are estimated by using a numerical model or methods derived specifically for hand-dug wells. Because of the unique geometry of hand-dug wells (diameters on the same order as well lengths), care must be taken to ensure that the proper shape factors are used with slug-test methods. Because of the substantial well storage in hand-dug wells, considerable time may be required to lower the water level to the desired position, especially if pump capacity is limited. This pumping time results in a noninstantaneous withdrawal of water from the aquifer, which violates one of the assumptions of slug-test-interpretation methods. However, in low-permeability environments, reasonable results can still be attained if water removed from the well sources from well storage or if recovery time is considerably longer than pumping time.

[1]  J. Premchitt,et al.  Shape factors of cylindrical piezometers , 1980 .

[2]  J. Barker.  Generalized well function evaluation for homogeneous and fissured aquifers , 1985 .

[3]  A. Moench,et al.  Transient Flow to a Large‐Diameter Well in an Aquifer With Storative Semiconfining Layers , 1985 .

[4]  T. D. Streltsova,et al.  The drawdown near an abstraction well of large diameter under non-steady conditions in an unconfined aquifer , 1976 .

[5]  R. Herbert.  Interpreting recovery data from pumping tests , 1990, Quarterly Journal of Engineering Geology.

[6]  R. Lai,et al.  Nonsteady flow to a large well in a leaky aquifer , 1974 .

[7]  H. H. Cooper,et al.  Drawdown in a well of large diameter , 1967 .

[8]  U. Jose,et al.  A digital simulation model for the unsteady-state radial flow to a dug well , 1986 .

[9]  V. Singh,et al.  Hydrogeological parameter estimation from pump tests on a large diameter well , 1986 .

[10]  H. Bouwer,et al.  A slug test for determining hydraulic conductivity of unconfined aquifers with completely or partially penetrating wells , 1976 .

[11]  K. Rushton,et al.  Estimating Aquifer Parameters for Large‐Diameter Wells , 1981 .

[12]  G. C. Mishra,et al.  Analysis of Flow to a Large-Diameter Well During the Recovery Period , 1985 .

[13]  Jr . James J. Butler,et al.  Slug tests in site characterization; some practical considerations , 1996 .

[14]  H. Bouwer.  The Bouwer and Rice Slug Test — An Updatea , 1989 .

[15]  C. V. Theis.  The relation between the lowering of the Piezometric surface and the rate and duration of discharge of a well using ground‐water storage , 1935 .

[16]  G. C. Mishra,et al.  Drawdown at a large-diameter observation well , 1991 .

[17]  M. J. Hvorslev.  Time lag and soil permeability in ground-water observations , 1951 .

[18]  R. Sakthivadivel,et al.  Numerical analysis of large-diameter wells with a seepage face — Reply , 1990 .

[19]  Robert P. Chapuis,et al.  Shape Factors for Permeability Tests in Boreholes and Piezometers , 1989 .

[20]  New approaches to pumping test interpretation for dug wells constructed on hard rock aquifers , 1992, Geological Society, London, Special Publications.

[21]  J. Black,et al.  Slug tests in fissured aquifers , 1983 .

[22]  V. Singh,et al.  Flow regime associated with partially penetrating large-diameter wells in hard rocks , 1988 .

[23]  J. D. Bredehoeft,et al.  Response of a finite-diameter well to an instantaneous charge of water. Paper No. H-21 , 1966 .

[24]  Gary R. Chirlin,et al.  A Critique of the Hvorslev Method for Slug Test Analysis: The Fully Penetrating Well , 1989 .

[25]  James J. Butler,et al.  Slug tests in partially penetrating wells , 1994 .

[26]  S. P. Rajagopalan.  Analysis of dug-well test data , 1983 .

[27]  G. C. Mishra,et al.  Analysis of Unsteady Flow to a Large‐Diameter Well Experiencing Well Loss , 1992 .

[28]  K. Rushton,et al.  Seepage and groundwater flow : numerical analysis by analog and digital methods , 1979 .

[29]  G. Kruseman,et al.  Analysis and Evaluation of Pumping Test Data , 1983 .

[30]  G. C. Mishra,et al.  Analysis of Flow to a Large‐Diameter Well Discrete Kernel Approach , 1983 .

[31]  James J. Butler,et al.  Slug Tests in Unconfined Formations: An Assessment of the Bouwer and Rice Technique , 1995 .

[32]  J. A. Barker,et al.  Nomograms for the analysis of recovery tests on large-diameter wells , 1989, Quarterly Journal of Engineering Geology.

[33]  Henry J. Ramey,et al.  Analysis of ''Slug Test'' Or DST Flow Period Data , 1975 .