Answer: They lead to contaminated groundwater / water supplies and can cause erosion, sinkholes, and landslides.
Explanation: Chemicals in tailing piles could leach into the soil and contaminate the groundwater. This could negatively impact the water supply for any surrounding towns or cities. Also, tailing piles can cause erosion, sinkholes, and landslides since there are no trees or plants there to hold the sediments in place with their roots.
