KENNECOTT (SOUTH ZONE)
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The Kennecott South Zone includes the Bingham Mining District in the Oquirrh Mountains, about 25 miles southwest of Salt Lake City, Utah. The area includes Bingham Canyon open pit mine, associated waste rock dumps, the Copperton Mill and many other historic sites. Mining activities at the site began in the 1860s and continue today. The resulting wastes contain hazardous substances, including heavy metals. Soils and sludge are contaminated, as are surface water and groundwater, which affect wetlands between the site and the shore of Great Salt Lake. Cleanup is ongoing. The site is not listed on the National Priorities List (NPL) but is considered to be an NPL-caliber site and is being addressed through the Superfund Alternative Approach.
What Has Been Done to Clean Up the Site?
In 1990, EPA and UDEQ discovered homes had been built on former flood plains contaminated with high levels of lead and arsenic. Kennecott and ARCO, with community input and oversight by EPA and UDEQ, conducted studies to determine the nature and volume of the contaminated wastes.
On January 18, 1994, the Kennecott South Zone was proposed to the National Priorities List (NPL). However, on September 3, 2008, EPA officially withdrew the proposal to place the site on the NPL due to the development of a memorandum of understanding. Pursuant to this memorandum of understanding (MOU) between EPA, UDEQ and Kennecott, signed in September 1995, Kennecott agreed to complete numerous cleanup projects for the site as well as the nearby Kennecott North Zone.
Since 1995, UDEQ, EPA and Kennecott have collaborated to expedite field work and reduce potential exposures from legacy mine waste. As a result of the cleanups, Kennecott has reduced potential exposure in the surrounding communities and on private property. Five-year reviews of remedial actions implemented to date concluded that remedial action objectives have been achieved. There was a five-year review completed on May 6, 2016. The five-year review concluded the remedies are not protective in the long-term because operation and maintenance and institutional control issues need to be resolved. Kennecott has assisted with implementing the recommendations identified in the five-year reviews.
There are multiple RODs for the South Zone:
- 1998 – Bingham Creek ROD OUs 1, 4, 5, 10, 11, and 17
- 2000 – Groundwater ROD OUs 2, 12 and 16.
- 2001 – Butterfield ROD OUs 3, 6 and 7
- 2002 – Kennecott North Zone & South Zone ROD OUs 18, 20 and 24
In addition, cleanup and treatment designs have been conducted in coordination with a Natural Resource Damage Settlement and a water treatment plant began operation in the spring of 2006.
On May 21, 2008, EPA finalized a Remedial Design/Remedial Action Consent Decree, which was amended in June 2009 for OU2. This prescribed future cleanup activities and put into place an enforcement mechanism and financial assurance to ensure that the cleanup and the operation and maintenance of the remedy will continue.
Kennecott will manage and respond accordingly to community concerns about the site and potential off-site releases.
What Is the Current Site Status?
The site consists of multiple areas, referred to by EPA as operable units (OUs). There are fifteen OUs and cleanup and monitoring is on-going. The OUs are as follows:
- OU1 Bingham Creek
- OU2 South End Groundwater
- OU3 Butterfield Canyon and Herriman
- OU4 Bingham Reservoirs (previously called Large Bingham Reservoir)
- OU5 ARCO Tailings: Bastian Ditch
- OU6 Lark Waste Rock and Tailings
- OU7 South Jordan Evaporation Ponds
- OU10 Copperton Soils
- OU11 Bingham Canyon Historic Facilities
- OU12 Water Collection System (previously called Eastside Collection System)
- OU16 Bingham Canyon Underflow (previously called Bingham Creek Underflow)
- OU17 Bastian Sink
- OU18 Mine Drainage: Tooele County (previously called Acid Mine Drainage)
- OU20 Pine Canyon
- OU24 Precipitation Plant
Kennecott is working on the South Dump Stabilization project, east waste rock extension project, groundwater corrective actions and soil cleanups taking place via oversight with UDEQ and EPA. These projects will greatly reduce the risk of sediment run-off during storm related events.