The TWG envisioned that the model would be used to simulate outcomes of proposed reclamation scenarios put-forth during the EIS process. Constraints put on this effort by the TWG include: 1. the model must be widely used and widely accepted; 2. the model must be able to be updated as new information is gathered. 3. the model must be able to be modified to reflect proposed reclamation scenarios with minimal pre-processing effort; 4. the model must be able to be run on a platform that is commonly used; and 5. the output of the model must be able to be conveyed to the decision makers with minimal post-processing effort. AESE determined that MODFLOW/MODPATH could meet the aforementioned modeling requirements and that a shell model developed using AutoCad could be used to minimize pre-and-post processing efforts.
The geologic shell model (GSM) consists of 14 filterable layers that can be viewed/modified using AutoCad Release 13. The term "shell" as used herein is a three dimensional feature bounded by irregular surfaces. A shell differs from a solid in that no data are present within or linked to the interior of each shell.
The (GWFM) discretizes the study area using 25,536 blocks that are 200 feet long by 200 feet wide by 100 feet high. This rather fine discretization interval serves several purposes: (1) it enables the model to accommodate proposed alternatives such as drains at the very localized scale without having to reconstruct/redescretize the model domain; (2) it allows for analysis of localized phenomena such as flow in the vicinity of the pits; and (3) it results in a more realistic model capable of utilizing structural and geomorphic information. The results of two simulations applied to the GSM are given. This wire-frame also has been animated using 3D Studio and is being used to educate participants involved in the EIS process.
AESE determined that the problem could be solved using a kaolin-based grout. This grout was selected for the following reasons: (1) its physical properties are only slightly affected by pH; (2) it is relatively plastic and heals itself in response to further ground-shift; (3) its low viscosity and long gel-times allow for relatively deep emplacement in low-permeable rocks; (4) unlike chemical grouts, kaolin is not hazardous to the environment; and (5) the grout is cheaper than Portland cement.
The team diminished flow and subsequently heavy-metals issuing from the structure by core-drilling five NX holes into and beyond the fault/fractures in a radial fan pattern. Pneumatic packers and a grout pump were used to emplace the grout.