Ridgeway mine

A former gold mine that operated from 1988 to 1999

RIDGEWAY, FAIRFIELD COUNTY, SOUTH CAROLINA
Ridgeway is a former gold mine operated by Kennecott Ridgeway Mining Company, a wholly owned subsidiary of Rio Tinto, from 1988 to 1999.

The mine is located approximately 5 miles east of Ridgeway, South Carolina, in the US.  

The former mine has been rehabilitated into a stable landscape that supports local ecosystems. In 2020, we started the post-closure monitoring phase which will continue for approximately 30 years to ensure that the closure of the site was effective. 

The closure program at Ridgeway

The Kennecott Ridgeway Mining Facility, formerly a gold and silver mine (from 1988–1999), is a 2,000-acre site located 20 miles north of Columbia, South Carolina, 7 miles from I-77, and 4 miles east of downtown Ridgeway.

Now under active reclamation, Kennecott Ridgeway, a subsidiary of Rio Tinto, oversees rehabilitation efforts to ensure the site remains safe and stable. 
In its third phase of reclamation, we're prioritising environmental stewardship through permit compliance, monitoring, equipment and vegetation maintenance, and acid rock drainage control, reflecting our commitment to sustainable site management.

$30m

invested in reclamation

800+

acres revegetated

Remediation needs 

The mining property is 2,000 acres of mostly forested land; of those, 903 acres were disturbed.  

Mining operations produced tailings and waste rock, much of which was prone to acid rock drainage (ARD) and required careful management.  

The mine included 2 open pits with sulphide-bearing rock exposed on the pit walls. Managing the sulphide-bearing pits and the tailings facility was particularly challenging due to the amount of rainfall in the subtropical environment typical of the southeastern US.

Remediation progress 

The $30 million reclamation work focused on managing the potential ARD contaminant sources from the mine pits and tailings facilities, while establishing a long-term stable site.  

By 2002, the revegetation of all previously disturbed and subsequently restored land surfaces was completed. 

Today, the site consists of 2 80-acre freshwater lakes, wetlands and a 380-acre tailings storage facility, now transformed into a tall grass prairie that’s home to numerous bird and other wildlife species.  Through thoughtful rehabilitation planning and long‑term care, this former mine has been transformed into a stable landscape. What was once an industrial mine site is now a natural landform of forests, lakes and ponds that once again support local ecosystems. Ridgeway was formally recognised by the South Carolina Department of Health and Environmental Control, the Interstate Mining Compact Commission, and the US Department of the Interior for best practices and sustainability in the reclamation of the site's 2 open pits, tailings facility and surrounding mine property.

  • Work completed

    During 1999 to 2003, we conducted a range of rehabilitation activities on site, including: 

    • stabilising tailings by covering them with a benign, fine-grained rock mixture 
    • dismantling and removing processing facilities and equipment 
    • developing a waterway channel system to carry water to and from various ponds and the pit lakes 
    • filling both open pits with water to create 2 freshwater lakes 
    • revegetating disturbed areas  

  • Technical innovation

    The techniques used at Ridgeway helped inform new ways to manage ARD across the industry.

    To prevent ARD generation in the mine pits, we moved 18 million tons of acid-generating waste rock to the bottom of the 2 mine pits. We then flooded the pits with runoff water collected from around the site, covering the pyrite-bearing waste and pit walls with water. This remedial design minimises acid rock drainage by limiting the amount of sulphide-bearing rock exposed to oxygen. 

    By flooding the mine pits, we were also able to create ecologically sustainable pit lakes that support a healthy aquatic community.  

    We used the remaining waste rock to construct an innovative technique for managing tailings waste: we covered potentially acid-generating tailings with a benign, fine-grained rock slurry. This created a 3-6-foot cap of material that supports healthy vegetation, preserves runoff water quality and maintains saturated conditions in the underlying pyrite-bearing tailings, effectively controlling ARD generation.

  • Water management system

    Ridgeway is in a sub-tropical environment typical of the south-eastern US, and so the tailings storage area was designed to withstand a probable maximum precipitation rain event of 44 inches in 24 hours. 

    We designed and constructed a perimeter crest and spillway at the tailings facility to handle the huge water flows calculated to be produced during such an unlikely event. This was connected to a further series of spillways and a wetlands area downstream of the tailings facility, leading to one or both pit lakes. The wetlands linking the 2 lakes provide stormwater runoff surge capacity as well as enhancing the overall aesthetics and biodiversity of the site.  

    Since 2003, we have conducted ongoing, detailed chemical, physical and biological monitoring of the pit lake, actively managing water levels and water quality. Water monitoring indicates that water can be discharged from the site without further treatment, making the lakes a potential sustainable water source for the surrounding community. 

  • Future work

    Ridgeway is in active closure and maintenance to ensure the site meets industry standards and regulatory requirements. 

    We’re responsible for environmental stewardship of the site, such as permit compliance, periodic monitoring, maintenance of equipment and site vegetation, and management of acid rock drainage. Our ongoing work also includes maintenance of the tailings storage facility, the pit lakes, water storage facilities and other associated systems and equipment.

Transparency and sharing knowledge 

Since the 1990s, we have worked closely with the community and regulators to manage Ridgeway’s mine closure. 

We maintained early and transparent communication with the local community – many of whom had previously held concerns about the development of the mine in the 1980s. For example, once the pit lakes and tailings closure plans were agreed with technical experts and the state’s regulatory agencies, we presented the plans to the community through media and public meetings. 

This transparent approach also contributed to important learning opportunities for the mining industry, ecology, biology and engineering students, and regulators. 

Next steps 

In January 2020, we started the post-closure monitoring phase which will continue for approximately 30 years to ensure the performance of all systems.  

We’re evaluating future options through a feasibility study to ensure the facility can continue to be managed in a safe, stable, and environmentally responsible manner and to evaluate options for future land uses.

Ridgeway’s history 

The Ridgeway mine in South Carolina was an open pit, precious metal mine that produced a dorébar, a semi-pure alloy of gold and silver, composed of approximately 60 percent gold and 40 percent silver.  

It operated from 1988 through to 1999, employing more than 180 people, and produced 1.5 million ounces of gold and 0.9 million ounces of silver.

Ridgeway

E: RTCAmericas@riotinto.com
T: 1-888-988-0832