Bonita Peak Operable Unit 3 (OU3) Groundwater Project
More than 130 years of mining operations have contaminated the soil, groundwater, and surface water of the Bonita Peak Mining District Superfund site (BPMD) with heavy metals. Dispersed across three watersheds, many of the site’s 48 sources continue to release metal-contaminated water and sediments into the environment. To help remediate these conditions, Schnabel was called in to lead the installation of three wells, which reach depths of up to 1,300 feet, at elevations of 10,000 to 12,000 feet.
Mining began in the southern San Juan Mountains of Colorado in the 1870s. Both large- and small-scale mining operations continued into the 1990s, with the last mine ceasing production in 1991. As a result, water quality at the BPMD has been impaired by acid mine drainage for decades. The site’s 48 sources of mining related contamination include historic hardrock mines, tailings, and waste rock, within the Mineral Creek, Cement Creek, and Upper Animas River drainages in San Juan County, Colorado.
Sunnyside Mine is one of the largest features in BPMD, and a major source of heavy metal-laden flows into Mineral Creek, Cement Creek, and the Upper Animas River. To characterize the water quality and pressure within the flooded mine, three monitoring wells were designed to characterize in situ conditions, conduct tracer studies, and conduct in situ treatability studies on the impounded mine water.
Schnabel led the installation of the three wells into the F-Level and G-Level workings within Sunnyside Mine. The Schnabel team was responsible for developing drilling specifications; digitizing hand-drawn mine maps from the 1980s; confirming these maps were accurately reprojected into State Plane coordinates for precise drill hole targeting; and managing field staff during the drilling, reaming, and casing of the wells. Drilling techniques included triple-tube wireline rock coring and directional drilling (using the Devico system) to intercept targets within several feet of the desired coordinates, at depths of more than 700 feet.