Designing Funnel-and-Gate Groundwater Remediation Systems Near Property Corners

摘要

Numerical models were used to simulate alternative funnel-and-gate groundwater remediation structures near property corners in hypothetical homogeneous and heterogeneous unconfined aquifers. Each structure comprised a highly permeable central gate (hydraulic conductivity = 25 m/d) and soil-bentonite slurry walls (hydraulic conductivity = 0.00009 m/d). Gates were perpendicular to regional groundwater flow and approximately 5 m from a contaminant plume's leading tip. Funnel segments collinear to the central gate reached property boundaries; additional funnel segments followed property boundaries in the most hydraulically upgradient direction. Structures were 1 m thick and anchored into the base of the aquifer. Two structures were simulated for each aquifer: one with a 3.0-m-long central gate and funnels on either side; and a second with a 1.5- m-long central gate, funnels on either side, and 0.75-m-long end gates. Funnels were lengthened in successive simulations, until a structure contained a contaminant plume. Results suggest that, for the same total gate length, one-gate structures may facilitate more rapid remediation, up to 44 percent less time in trials conducted in this study, than multiple-gate structures constructed near property corners. However, in order to effectively contain a plume, one-gate structures were up to 46 percent larger than multiple-gate structures.