NPL Partial Site Deletion NarrativeCalifornia Gulch
On April 16, 2001, EPA deleted Operable Unit 10 - Oregon Gulch (OU10) of the California Gulch site from the National Priorities List (NPL).
The California Gulch site is located in Lake County, Colorado approximately 100 miles southwest of Denver. Located in a highly mineralized area of the Colorado Rocky Mountains, the California Gulch site covers 16.5 square miles of the watershed that drains along the California Gulch to the Arkansas River.
According to the 1994 Consent Decree, the site was divided into 12 Operable Units in order to expedite clean up. Operable Unit 10 - Oregon Gulch is delineated as the 500-year flood plain of the Oregon Gulch from its headwaters to its confluence with the California Gulch, approximately 1/2 mile south of the City of Leadville.
In accordance with the August 1995 Action Memorandum, a removal action was completed at OU10 in 1995 and 1996. This removal action focused on the eroded tailings and contaminated sediments in the Lower Oregon Gulch. Following the Focused Feasibility Study (FFS) in June 1997, EPA issued a Record of Decision (ROD) for OU10 on August 7, 1997. In 1998 remedial actions began at OU10. The focus of the remedial action was to prevent infiltration of water into the tailings, prevent erosion of the tailings and to treat and eliminate the impoundment seep.
The EPA and the State of Colorado have determined that all appropriate CERCLA Response actions have been completed and Operable Unit 10 - Oregon Gulch poses no significant threat to human health or the environment. Therefore, EPA is deleting Operable Unit 10 - Oregon Gulch of the California Gulch Superfund Site from the National Priorities List (NPL).