A new permeameter is proposed for performing laboratory hydraulic conductivity tests on gravels with hydraulic conductivity values ranging from 0.1 to\ 1\ \ m/s1\ \ m/s. A small diameter riser is connected to a large diameter cylinder, which holds the coarse-grained specimen saturated in a water bath. The release of pneumatic pressure, applied to the free surface in the riser, induces an underdamped oscillatory response of the water level in the riser, similar to an underdamped in situ slug test response in monitoring wells. A closed-form model is used to analyze the measured oscillatory hydraulic head data to calibrate the minor losses in the permeameter and the hydraulic conductivity of the specimen by performing tests without and with a specimen. The average model error of calibrated pressure head values in the riser for the tests considered are about 5\% of the initial displacement of about 2\ cm. The hydraulic conductivity values are calibrated considering the replicate tests, the tests of different specimen lengths, and the different time periods within a test to verify that the results reflect the hydraulic conductivity of the specimen alone. The Kozeny-Carman equation, which considers the specific surface area of the tested material, gave a hydraulic conductivity value within 5\% of the measured value for the marbles, which is a good comparison because the uniform marbles have a known specific surface area. For all the various tests performed on each specimen, most of the hydraulic conductivity values were within 10\% of the average, while the specimens with hydraulic conductivity greater than\ 1\ \ m/s1\ \ m/s\ were within 10 to 20\% of the average.

}, keywords = {Gravel, hydraulic conductivity, Laboratory test, Models, Optimization, Porosity, Soil water, Tortuosity, Underdamped, Water flow}, doi = {10.1061/(ASCE)HE.1943-5584.0000813, 319-327}, author = {Judge, Aaron I. and Ostendorf, David W. and Degroot, Don J. and Zlotnik, Vitaly A.} } @article {11489, title = {A linear theory of slug tests with annular effects}, journal = {Journal of Hydrology}, volume = {368}, year = {2009}, month = {4/2009}, pages = {205{\textendash}213}, chapter = {205}, abstract = {We derive a closed form theory of water level fluctuations caused by slug tests in a well with an annulus that extends to the piezometric surface. This hydraulics can be created by small diameter slug test equipment in a large diameter well, with an annulus established by borehole casing and the riser pipe of the equipment. The conservation of mass equation couples aquifer hydraulics, core hydraulics inside the riser pipe (which include inertia), and annular hydraulics outside the riser pipe (which include inertia and linear friction). The linear friction is needed to attenuate oscillations between the core and annulus, which would otherwise persist indefinitely after damping of aquifer discharge. A characteristic velocity is adopted for the annular friction, so that aquifer permeability is the sole calibration parameter. We calibrate the theory with overdamped and underdamped experiments run in a limestone aquifer at the Hydrogeological Experimental Site of Poitiers in France by Audouin, O., Bodin, J. 2007. Analysis of slug tests with high frequency oscillations. Journal of Hydrology 334, 282\–289. The data and analytical theory yield plausible, accurate permeability estimates of 4.1\ \×\ 10\−12\ and 1.7\ \×\ 10\−11\ m2. Portable, small diameter slug testing devices may accordingly be used in permanent, large diameter cased boreholes to estimate aquifer permeability, although the annular effects can obscure aquifer hydraulics. The annular effects may also occur in slug tests on wells with skins, bypasses, and packers, although different boundary and matching conditions would be needed to model this hydraulics.

}, keywords = {Annulus, High permeability aquifers, Oscillations, Slug test, Well hydraulics}, doi = {10.1016/j.jhydrol.2009.02.003}, author = {Ostendorf, David W. and Zlotnik, Vitaly A. and Degroot, Don J.} }