OSWER/OSRTI Washington, DC 20460



## N ATIONAL 

## P RIORITIES 

## L IST 

## (NPL)

[The description of the site (release) is based on information av ailable at the time the site was evaluated with the HRS. The d escription may change as additional information is gathered on the sources and extent of contamination.]

For more information about the hazardous substances identified in this narrative summary, including general information regardi ng the effects of exposure to these substances on human health, please see the Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs. ATSDR ToxFAQs can be found on the Internet

at http://www.atsdr.cdc.gov/toxfaq.html or by telephone at 1-888-42-ATSDR or 1-888-422-8737. ***Proposed Site*** March 2011 

### MOLYCORP, INC. Questa, New Mexico

Taos County

à Site Location:
The MolyCorp, Inc. site (MolyCorp) is a molybdenum mining site located near the village of Questa, Taos County, New Mexico and consists of two separate areas: the mine and the tailing ponds. The mine itself is approximately 3 square miles in size and is surrounded by the Carson Na tional Forest and the state-designated Latir Peak Wilderness Area, which is located approximately two miles north of the mine. The tailing facility, which is approximately one square mile in size, is located 6 miles west of the mine site in the village of Questa . The mine is located near the Red River and includes several side drainages, including Sulfur Gulch, Spring Gulch, Goathill Gulch, and Capulin Canyon.

 ́ Site History:
Chevron Mining, Inc. (CMI), currently owns and operates the MolyCorp mine site. The mining operation has been active for the last 90 years, with three distinct operational pha ses: (1) conventional underground mining, which occurred from about 1919 to 1958, (2) open pit mining, which was conducte d from 1965 to 1981, and (3) underground block cave mining, which started in 1983 and continues to the present. As part of the current operations, the facility also consists of a mill, a tailing facility, and a tailing pipeline that runs between the mine and the tailing facility.

r Site Contamination/Contaminants:
Sources evaluated include the open pit mine, waste rock p iles, contaminated soil in the mill area, tailing impoundments, and the tailing pipeline. Primary contaminants present in on-site sources include polychlorinated bi-phenyls (PCBs), molybdenum, and other heavy metals. Antimony, boron, cadmium , cobalt, manganese, molybdenum, nickel, vanadium,

and zinc were detected in the Red River.

v Potential Impacts on Surrounding Community/Environment:
Hazardous substances, contaminants and pollutants from the mining-related sources have released into the soil, ground water, surface water and sediment at and in the vicinity of the mine site and ta iling facility, including the surface water of the Red River, which flows in a westerly direction just south of the site. A release of hazardous substances has been

documented in both surface water and sedime nt within the Red River, including the Red River Fish Hatchery, which is

located downstream of the site. Both a Human Health and Ecological Risk Assessment have been completed at the site, and identified unacceptable risks to human health and the environment.

3 Response Activities (to date):
An RI/FS has been conducted through an Administrative Orde r on Consent between EPA and Chevron. Chevron currently is working in conjunction with the State and EPA to address ongoing releases.

} Need for NPL Listing:
The site was initially proposed to the NPL in May 2000. EPA is re-proposing to ensure that site score more accurately reflects current site conditions obtained since the May 2000 proposal.