Analysis of slug tests to determine hydraulic conductivity of vertical cutoff walls

Analysis of a slug test in a vertical cutoff wall is complicated by the high compressibility of the backfill materials and by the geometric system in which a well intake section that includes a screen and filter pack section is located close to the edge of the cutoff wall.; The purpose of this study was to: (1) investigate existing methods for analyzing results of a slug test in a vertical cutoff wall; (2) develop a computer program for analyzing results of a slug test in a vertical cutoff wall; (3) provide a series of type curves that consider the geometry of a cutoff wall and eccentricity of a well screen; (4) modify the conventional curve fitting method to consider the geometric complications in a cutoff wall; (5) evaluate the effect of variable hydraulic properties on results of a slug test; and (6) consider practical concerns in a slug test with respect to the installation of a well and construction of a vertical cutoff wall.; The primary contribution made in this research is to develop two new methods to evaluate hydraulic conductivity in a cutoff wall considering the compressibility of the backfill material and the proximity of the wall boundaries to the well. One of the new methods involves a series of type curves that takes into account the compressibility of the backfill, overall effect of narrow wall boundaries, and eccentricity of the well intake section. The second new method is a modified curve fitting method, which employs a linear curve fitting method such as the Bouwer and Rice method, a modified effective radius, and a reduction factor. Both of these new methods provide a more rigorous and accurate estimate of hydraulic conductivity compared to previously available methods. Both new methods are practical and easy to use.