EJQ4 - Spring 2025 - Journal - Page 51
Dewatering from the vertical shafts minimizes the amount of inpit pumping needed, which typically uses more hoses and pumps
than pumping from the shaft. Additionally, by pumping from the
underground workings and maintaining the water level in the
workings some depth below the base of the pit provides storage
capacity for rainfall or snowmelt. This ability to store water allows
water to be pumped at a consistent rate, creating a more e昀케cient
water treatment process. This also allows mines to maintain a
dry pit to limit potential downtime after signi昀椀cant rain events or
snowmelt.
developments should consider the reprocessing of historical
tailings. At times, enough commodity can be extracted from the
historical tailings to pay for the cost of reprocessing and mitigating
the e昀昀ect they have on the environment.
Managing seepage from new and old sources
We can mitigate seepage further still by accounting for
groundwater 昀氀ow patterns when considering the placement of
tailings facilities and waste rock piles. Placing these facilities in
the groundwater 昀氀ow path of the open pit allows seepage to be
captured by the open pit. During operations the groundwater
intercepted by the open pit is pumped from the open pit and
treated, if needed. In closure, if a pit lake forms, the pit lake has a
greater assimilative capacity for the seepage that enters the open
pit and passive treatment (constructed wetlands) can be used to
treat the water at the outlet of the pit lake, if needed.
Many old mines have historical tailings that were placed on land and
occasionally into lakes without containment or control of seepage.
As a result, these historical tailings often impact nearby lakes and
rivers. We can improve on legacy environmental impacts through the
management of historical tailings.
Over the years, technology has improved, allowing a lower grade of
ore to be extracted and commodity recovered. Therefore, new mine
New mine developments include engineered facilities to manage
tailings and control seepage. Whether through reprocessing or
relocation, placing historical tailings in these new engineered
facilities can mitigate legacy environmental impacts as they allow
for the collection and treatment of seepage prior to discharge.
E N V I RON M E N T J OURN A L QUA RT E RLY RE PORT • S PRI N G 2 0 2 5 • P AGE 5 1
