Description

This paper describes a Excel spreadsheet for estimating the hydraulic conductivity of saturated geologic materials. Results are generated simultaneously using the methods of Bouwer and Rice (1976, 1989, 1989a) and of Hvorslev (1951). The spreadsheet-based platform allows open access to calculation formulae, allowing modification and improvement by users. It is assumed that users are familiar with the theory and practice of slug testing. Once familiar with the operation of the worksheet, users typically perform a complete analysis of ASCII formatted time-level data in 15 to 30 minutes. If data are not of sufficient quality to quickly identify a linear range for analysis, additional evaluation will be required. Workers and managers who encounter such data should evaluate the applicability of the theory supporting this type of analysis and make case-by-case decisions regarding the validity of the results.

Features

Primary features of the worksheet include:

• Double Straight-Line Effect. In "water table" or "drained" wells, where the length of the open interval equals or exceeds the length of the well, sand pack drainage is automatically calculated and compensated for by the worksheet.
• Estimation of Effective Radius. Bouwer and Rice parameters A, B, and C are automatically estimated for each test, based on a fifth-order polynomial regression to the curves presented in the original paper.
• Response Curve Selection. The straight-line portion of the response is selected by the user on the basis of a graphic display of the test data. This increases quality by ensuring that the data used for computation of the hydraulic conductivity do fit a straight line in the test data, a prerequisite for accurate analysis. Final output includes a graph of the predicted drawdown line and the observed data, encouraging visual evaluation of the quality of the data and the solution.
• Macro Support. Data import and regression of the fit line can be performed by macro, in addition to the manual procedure that is integral to the spreadsheet format.

Distribution

This template may be distributed and used and reproduced freely in accordance with the general public license of the Free Software Foundation (this, however, does not implied that this code was developed or reviewed by the FSF). In transferring the software, users should ensure that all supporting documentation and code is included, and all internal validation data sets and routines remain intact. This documentation file is 'slug096b.htm' and the spreadsheet files is slug096b.xls (the numeric part of the file name reflects the current version number, and will increase with each upgrade). Version 0.95 has been used in practice with Excel 5, but is considered late-BETA because it has not has not undergone a period of open testing. Version 0.96 changes are to convert to Excel 97 (and 2000 when I get a license). Primary goals for Version 1.0 will be to document independent testing, and to incorporate checksum/PGP based verification into the distribution. Users who update or improve the application are encouraged to submit their modifications for possible inclusion in future versions. All users are encouraged to provide comments and suggestions regarding future improvements to the primary author, Karl DeBisschop (kdebisschop@users.sourceforge.net).