Finite Line Relief Well System Design for Dams and Levees: Fid-Bau Portal

Finite Line Relief Well System Design for Dams and Levees

Keffer, Andrew M. / Guy, Erich D. / Grote, Katherine R.

An analytical method is commonly used to design relief well systems by assuming the well line extends an infinite distance parallel to the dam or levee. This assumption may be met in some cases, but when a well line is of finite length, this can severely underestimate excess heads. Although these consequences have been historically recognized, a practical graph-based analytical approach for finite well line design has not been developed. Finite well lines exist and continue to be installed at many locations, so this study developed a practical design method for such systems. Analytical solutions and numerical models were used to improve understanding of the performance of partial and full penetration finite well systems. Performance was found to be dependent on well system geometry, the ratios of effective seepage entry and exit distances to well spacing, and the number of wells. Model results were used to develop new uplift factors that more accurately define excess heads along and landward of finite well systems that fully or partially penetrate the aquifer.