I’m a Hydrogeologist that studied ACID Rock Drainage at the Halifax Stanfield Airport for 4 yrs in the early 1980s and published papers in scientific journals,  so I understand how it forms, how long it lasts and its negative impacts in receiving watercourses via groundwater discharge. ARD will take 1-2yrs to generate and will last for more than 25yrs. pH will be substantially lowered ( <4), oxygen depleted and toxic metals significantly increased (particularly Al) in the watercourses for several km downstream. Thiobaccilus microorganisms can still generate ARD under anaerobic conditions in the groundwater. Most of the ARD is generated within the “blast halo” surrounding the open pit, which is never addressed in the EAs, which it should be. Blasting opens up fractures around the pit, exposing mineralized pyrite and thereby creating ARD.
My biggest concern is the long term impacts to St. Mary’s River from the relatively nearby blast halo which will be created around the open pit upgradient from the river.