OSWER/OSRTI Washington, DC 20460


## N ATIONAL 

## P RIORITIES 

## L IST 

## (NPL)

***Final Site *** September 2011 

### CHEVRON QUESTA MINE Questa, New Mexico

Taos County

 **Site Location :**  The Chevron Questa Mine site , called the MolyCorp, Inc. site when it was proposed, is a molybdenum mining site located near the village of Questa, Taos County, New Mexico and consists of two separate areas: the mine area and the tailing ponds. The mine itself is approximately 3 square miles in size and is surrounded by the Carson National 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 d rainages, including Sulfur Gulch, Spring Gulch, Goathil l Gulch and Capulin Canyon.

 **Site History:** Chevron Mining, Inc. (CMI)

, currently owns and operates the Moly C orp mine site. The mining operation has been active for the last 90 years, with three dis tinct operational phases: (1) conventional underground mining, which occurred from about 1919 to 1958, (2) open pit mining, which was conducted 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.

 **Site Contamination/Contaminants:** Sources evaluated include the open pit mine

, waste roc k piles, contaminated soil in the mill area, taili ng impoundments and the tailing pipeline. Primary site contamin ants 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

.

 **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 a nd sediment at and in the vicinity of the mine site and tailing facility , including the surface water of the Red River

. A release of hazardous substances has been documented in both surface water and sediment within the Red River, including the Red River Fish Hatchery, which is located downstream of the s ite. Both a Human Health and Ecological Risk Assessment have been completed at the site, and identified unacceptable risks to human health and the environment.

 **Response Activities (to date):**
A Remedial I nvestigation and Feasibility Study ( RI/FS ) has been conducted th r ough an A dministrative Order 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 s ite was initially pr oposed to the NPL in May 2000. EPA is re

- proposing to ensure that the Hazard Ranking System site score more accurately reflects current site conditions obtained since the May 2000 proposal

. EPA received a letter from the state supporti ng listing of the site on the NPL. [The description of the site (release) is based on information available at the time the site was evaluated with the HRS. The description 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 regar ding the effects of exposure to these substances on human health, please see the Agency for Toxic Substances and Disease Registry (ATSDR) ToxFAQs. ATSDR ToxFAQs ca n 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.