Pit lakes have long been a legacy of large-scale open-cut mining. In earlier decades, pit lake closure plans surfaced late in the mine closure process. But at that late stage, remediation and reuse options become limited.
Today, we know the most successful pit lake closures come when they’re planned for early on. When you evaluate end-use options for pit lakes in your life-of-mine and mine closure plans, your chances for minimizing risk and maximizing value increase tremendously.
Here are five key steps to make your pit lake planning and outcomes more effective, sustainable and acceptable to all stakeholders.
1. Begin planning early: Develop pit lake closure strategies and designs within your life-of-mine and closure planning. Resist the tendency to let planning for above-ground landforms overshadow the planning needed for pit lakes — even if above-ground landforms are what your particular regulatory bodies tend to emphasize. You need a closure vision for the pit lake, too, or you may miss your only opportunity to include designs that would facilitate a better closure.
2. Be aware backfill isn’t your only option: Some regulators will require backfill for acceptable pit void closure despite greater cost or even detrimental environmental consequences. But many voids may be an equally or better-managed risk with a lake formation. Also, there may be the potential for access to water-based, end-use opportunities. Explore your options.
3. Facilitate cross-disciplinary collaboration: An effective plan will come from involving the multitude of disciplines present with pit lakes: surface and groundwater experts; stakeholder engagement and permitting specialists; geotechnical engineers; ground engineers; construction and design experts; ecologists and ecotoxicologists; and others. Take a holistic, multi-disciplinary approach and you’ll see the difference at closure.
4. Focus on water quality: If you want the option of transforming your pit lake into a new use in the future, you will need to focus on water quality. It’s water quality that will open up new reuse opportunities or shut them down. If that’s not an option, there are often treatment systems that can bring your water up to regulatory requirements.
5. Think beyond risk, see the opportunities: While the large size, large volume, poor water quality, and connection to regional water sources can present significant potential risk and liability for your company, there are a host of proven end uses that can produce valuable benefits to the community, your company and our environment. These can include:
- Swimming, diving and boating
- Amenities such as sightseeing and walking/bike riding
- Wildlife and fisheries habitat
- Treatment of other mine waters on the reclaimed or active mine site
- Water resources for flood attenuation and primary industries
Contact us to learn about pit lake solutions we’ve implemented for our clients — solutions that have reduced risk and increased value.
ABOUT THE AUTHORS
Jerry Vandenberg, MSc, works on client pit lake remediation and reclamation projects worldwide for Golder, and is actively involved in advancing the knowledge and improving the design of mine pit lakes. He earned his master’s in Environmental Chemistry at the University of Calgary. Jerry has authored or co-authored over 100 industry and academic publications.