Modeling the 3D net infiltration distribution at the Equity Silver Mine waste dump

• Main Author: Lin, Tai-Yi Debbie
• Language: English
• Published: University of British Columbia 2010
• Online Access: http://hdl.handle.net/2429/23635

The Equity Silver Mine site has been experiencing problems with ARD at its waste dump facility since 1981. A protective engineered soil cover was constructed over the top of the entire waste dump with the purpose of reducing ARD by impeding water and oxygen infiltration into the waste rock. Currently, there is a discrepancy between the 15% actual the 5% previously predicted infiltration. A new model illustrating the 3D net infiltration distribution over the surface of the Equity Silver Mine waste dump is presented in this thesis. The 3D infiltration model was developed through the integration of soil-atmosphere moisture flux and slope energy modeling. Verified soil properties from previous Equity Silver Mine waste dump soil cover modeling were used, in combination with updated climate data, to carry out the model development. The 3D models show that the difference in net infiltration at various slopes across the waste dump can vary as much as 15%, with infiltration of up to 30% on the north-facing side. Approximate quantification for the total flow into the waste rock layer showed that for the year of 2004, there can be up to 12% of total annual precipitation. Furthermore, it was also established that 35% of total infiltration into the cover occurs through the horizontal and south-facing dump surfaces, while 65% of the infiltration occurs through the north-facing and other sloped surfaces. Infiltration and flow increased by 42% when sloped Qnet values were applied. Areas of high infiltration over the surface of the waste dump were consistent for all net infiltration models developed. With the high infiltrative problem areas identified, Equity Silver site personnel can now use the newly developed 3D net infiltration model to navigate the locations where soil cover improvement would need to be implemented.