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10.0 SUMMARY
The GROUNDWATER IMPACT SCREENING MODEL presented in
this report was developed by Golder Associates to aid in
the evaluation of alternative sites and facility layouts
for a proposed tailings disposal system at Exxon's Crandon,
Wisconsin project.    The model uses a finite difference
groundwater flow solution and simulates seepage transport
using the "random walk" algorithm because of its simplicity
and rapid solution.    These features are necessary since
many analyses are required at the planning stages of site
evaluation.
This model is presently being applied at Exxon's Cran-
don, Wisconsin project for determination of relative im-
pacts of various siting alternatives and is functioning
well. In this application, the change in groundwater sys-
tem gradients are simulated over the analysis period. This
allows the relative evaluation of the effects of pond seep-
age on the groundwater system, including both the effect on
the groundwater gradients and the concentration distribu-
tion of pond seepage throughout the study area.
GO DER    OC ATES
Edmund Baker, P.E.
Associate
Gar H. Collison, P.E.
As ociate
JEB:GHC:dap

Golder Assoc ates

786085

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March, 1982