Laserfiche WebLink
Page C-2 <br />~ APPENDIX C <br />EVALUATION OF CHANGES ON THE HYDRAULIC <br />CONDUCTIVITIES IN THE AQUITARD AND AQUIFER <br />Evaluation of the impact of mining on the hydraulic conductivities of the aquifer and <br />aquitard was conducted based on influence of the stress changes on hydraulic conductivities of <br />the aquitazd (R-6) and B-Groove aquifer. The calculation utilized the hyperbolic normal stress <br />closure relationship (Goodman 1976) and the cubic flow rule in the fractured rock (Snow 1965). <br />The hyperbolic normal stress closure relationship describes the closure of fracture varying <br />hyperbolically with normal stress. The cubic flow rule is used to describe fluid flow in a frac- <br />ture, i.e. the volumetric flow rate is proportional to the cube of the effective joint aperture. <br />Figure C-1 graphically presents the major non-linearities of fluid flow in a fracture. The horizon- <br />tal post-mining states aze presented in Figures C-2 and C-3. Based on a generic hyperbolic nor- <br />mal stress closure curve as presented in Figure C-4, the ratio of the pre- and post-mining closures <br />for the vertical joints can be obtained with the stress information. The ratio of the hydraulic con- <br />ductivity is then directly obtained as the cube of the ratio for the closure. Figures C-5 and C-6 <br />present the estimation of the changes on hydraulic conductivities in the aquitaid and aquifer. <br />Agapito Associates, Inc. <br />