Challenge

Equinox Gold is reopening and expanding the Castle Mountain Gold Mine in San Bernardino County, California, while meeting stringent environmental regulations to ensure long-term groundwater protection, and support future ore processing capacity. The project required complex geotechnical engineering, heap leach pad design, regulatory permitting, water resource evaluation, and construction oversight across multiple project phases.

Solution

Geo-Logic Associates delivered a comprehensive engineering and environmental services program that supported the mine from permitting through construction. Our team performed geotechnical investigations, material testing, and engineering analyses to design a new heap leach pad partially overlying a previously closed facility. We developed the detailed design, plans, specifications, and construction quality assurance (CQA) program for the 65-acre Phase 1A expansion, including a sophisticated multi-layer liner and vadose zone monitoring system.

Beyond design and construction support, GLA prepared regulatory permitting documents, coordinated with the Colorado River Regional Water Quality Control Board, and developed compliance plans to satisfy new Waste Discharge Requirements (WDRs). We also created a three-dimensional groundwater flow model of the Lanfair Valley, identified sustainable water supply options, designed and installed new water supply and monitoring wells, and provided ongoing groundwater monitoring and reporting.

Results

GLA helped Equinox successfully secure WDR approval and advance the reopening of the Castle Mountain Mine. The facility is now operating with its new heap leach pad, enabling the processing of approximately 208 million tons of low-grade ore. Through integrated geotechnical, hydrogeological, permitting, and construction engineering services, GLA delivered a technically sound, compliant, and sustainable foundation for the mine’s long-term operation and expansion.

“Successful mining projects require more than good design—they demand a deep understanding of geotechnical performance, water resources, regulatory requirements, and constructability. By integrating these disciplines from day one, we helped Equinox move confidently from permitting to production while protecting the resources that matter most.”

— Doug Bartlett, RG, CHG - Vice President, Principal Hydrogeologist