Davidson Project: Update of MODFLOW Model

This document details an updated groundwater model for the Davidson EA. Key differences between this version of the model and the previous version are a change in the model domain to allow groundwater to flow to Glacier Gulch and Simpson Creek watersheds from the mine area, a revision of the mine grid so that the adits and mine could be treated as simple drains without internal inactive zones, an extensive sensitivity analysis of the key parameters, and more thorough transient simulations of 700 Adit development, mine operations, and post-closure.