North Star Mine – Grass Valley, CA

NorthStar Mine Gold Specimen - Grass Valley, CA
NorthStar Mine Gold Specimen – Grass Valley, CA

Holdrege & Kull performed a comprehensive site investigation and developed a draft remedial work plan for the historic 714-acre North Star group of mines located southwest of Grass Valley. H&K characterized approximately 50,000 cubic yards of mine tailings and waste rock contained in 68 assessment areas throughout the site. Remedial action includes: 1) off-site disposal of approximately 3,000 cubic yards of mine waste with volatile mercury concentrations presenting an indoor air risk; 2) land use controls for specific assessment areas that are to remain in place outside of the proposed residential development; 3) design for on-site placement and encapsulation of approximately 47,000 yards of mine waste under deed restriction and an operation and maintenance agreement; 4) remediation of two wetlands areas containing methylmercury; and 5) cleanup goals for recreational trail use.