OLEM/OSRTI Washington, DC 20460 

## N ATIONAL 

## P RIORITIES 

## L IST 

## (NPL)

*** Proposed Site *** Ap ril 2016 

### ARGONAUT MINE Jackson, California Amador County  **Site Location :**  The site is located with in a residential area in the city of Jackson, Amador County, California

.

 **Site History:** The Argonaut Mine wa s a historic hard rock gold mine that operated from the 1850s until 1942. The Argonaut Mining Company operated the mine and dissolved in 1948. At the stamp mills (known as the Mill Area), r aw ore was processed and mercury was amalgamated to extract gold fr om the crushed ore. T he mine tailings w ere transported and disposed of in a valley located approximately 1⁄2 mile south of the stamp mills (Tailings Area). The site includes impoundments, buildings, a mine shaft and headframe, earthen tailings dams, a 100- ye ar old concrete dam (Eastwood Multiple Arch Dam), and an old cyanide plant.
 **Site Contamination/Contaminants:** Soils in the Tailings Area and in residential properties adjacent to the Tailings Area are contaminated with arsenic, lead and mercury. W etland sediments in the Tailings Area are also contaminated with arsenic and mercury

.
 **Potential Impacts on Surrounding Community/Environment :**  Many residential properties have been built on top of or adjacent to the former mine processing areas . T he Argonaut Hi gh School is located approximately 250 feet to the west of the Tailings Area and Jackson Junior High School is 550 feet to the east of the Tailings Area. Residents and children are exposed to soil contaminated with high levels of arsenic, lead and mercury. There are wetlands located within the Tailings Area and intermittent wetlands within the Mill Area which flow into Jackson Creek

. In addition, an engineering study of t he Eastwood Multiple Arch Dam has shown that the dam is structurally unstable

. If there is a breach or dam fail ure , significant damage and possible injur ies or loss of life could occur.  **Response Activities (to date):** In March 2015, the EPA removed approximately 1,872 cubic yards of highly contaminated soil from a vacant lot located at the corner of Argonaut Lane and Pioneer Street

. The contaminated soil w as transported to a five acre parcel within the Tailings Area where a repository was constructed, capped and hydro

- seeded. I n July 2015, the EPA removed approximately 1,014 cubic yards of arsenic

- contaminated soils from 11 residential properties near the Tailings Area, and from an embankment at the Jackson Junior High School’s athletic field . T he embankment at the Jackson Junior High School w as capped and a fence was installed to protect the cap.

 **Need for NPL Listing:** The s tate of California referred th e site to the EPA in 201 3 to assist with response actions in the Tailings Area . None of the former corporate owners or operators are financially viable and there are no viable successors . N PL listing will allo w for a thorough investigation and cleanup of the site to protect the surrounding communities from exposure. Other federal and/or state programs were evaluated , but are not viable at this time. The EPA received a letter of support for p lacing this site on the NPL from the s tate of California.

[Th e de scription of

t he s ite ( release) i s bas ed on in formatio n availab le a t

t he t ime t h e s ite w a s e va lua ted with the H RS

. T he de scription ma y change as addi tional i nformation is gat hered on the s ources and extent of c ontamin ation. Se e 56 FR 5600, F ebruary 11, 1991, or

s ubsequent FR n otices.]

For more information about the hazardous substances identified in this narrati ve summary, including general information regarding 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/toxfaqs/index.asp or by telephone at 1

- 888

- 42

- ATSDR or 1

- 888

- 422

- 8737.