Client: New Mexico Environment Department (NMED)
Location: Grant County, New Mexico, USA
Challenge. Protect human health and the environment from elevated arsenic and lead concentrations in mill tailings located adjacent to a creek
Solution. INTERA conducted additional environmental investigation and reclamation activities at the San Vicente Creek Mill site, located just south of the Town of Silver City, address a mill tailings pile that had been abandoned on what is now privately owned land. The project was initiated by the New Mexico Office of the Natural Resources Trustee (NMONRT) using funds from a natural resources damage settlement with Freeport McMoRan Copper and Gold Inc. (FMI). The site is a former milling and smelting operations for lead, silver, copper, and gold that operated from the 1880s to the 1940s. As a result of these operations, an above-grade tailings pile remained at the site. The tailings pile contained metals, and in particular arsenic and lead, at levels that exceed established human health standards. Since emplacement/abandonment, the tailings pile had been actively eroding and had breached containment berms installed by the United States Environmental Protection Agency and one of the current private landowners. Surface water quality had been impacted by the erosion of the tailings pile and the subsequent transport of contaminated material to an adjacent creek. Groundwater also contained elevated concentrations of metals. INTERA performed additional investigation activities to determine the extent of tailings and contaminated soils, both on- and off-site; removed contaminated materials (approximately 50,000 cubic yards); transported and disposed of contaminated materials at FMI’s nearby Tyrone Mine; restored disturbed areas with placement of soil cover; and reseeded the area with a native seed mixture. Our approach to completing the work included performing additional characterization efforts while reclamation of the main tailings area was being conducted. The resulting single mobilization resulted in significant cost and time savings and a project that was completed ahead of the defined schedule.