What is the Investigation About?

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What is this Investigation About?

Why is a hazardous substance investigation necessary in the Watershed?

The U.S. Environmental Protection Agency has been investigating areas in the Silver Creek Watershed since the mid 1980s. The agency is determining whether a threat to human health or the environment exists from possible exposure to hazardous substances in the Watershed. The substances of concern in the Silver Creek Watershed include heavy metals, resulting from both natural sources and Park City’s mining history. Surface water, groundwater, and soils (including some mine wastes) are the areas of concern. There are several areas of interest in the Silver Creek Watershed, including but not limited to: Empire Canyon, Silver Maple Claims, Richardson Flat, and Lower Silver Creek.

How is work being conducted?

The Stakeholder Group is addressing three areas of concern, or pathways. These pathways are:

• Contaminated soils and exposed mine waste

Heavy metal contaminated soils are known to exist throughout the Watershed. Contaminated soils or dust could pose a threat to human health and could serve as a source of surface water contamination. EPA and the Stakeholder Group convened a group of interested residents and agency representatives to look at soil contamination in areas covered by the Park City Landscaping and Maintenance of Cover Ordinance. Called the Soils Ordinance Workgroup, their challenge was to ensure the Ordinance worked as intended and to ensure it functioned correctly over the long-term. The group met regularly until Park City Municipal Corporation, in cooperation with the Stakeholder Group, finalized its Environmental Management System in 2005. EPA believes this plan effectively addresses issues of soil contamination within the Ordinance area.

• Surface Water

Silver Creek does not meet state water quality standards for certain heavy metals and doesn’t fully support its beneficial use classification as a cold water fishery. The Stakeholder Group coordinated with the Utah Department of Environmental Quality effort to establish Total Maximum Daily Loads (TMDLs) for Silver Creek. Through a series of sampling events, the Stakeholder Group is investigating which areas or sources are causing the contamination. The group is then developing a plan for dealing with those sources.

• Groundwater and Drinking Water

Groundwater may be used as a resource for drinking or irrigation or may discharge to surface water. Due to the complex geology and the network of mine tunnels in the area, the groundwater system around Park City is very complicated. It is known that groundwater in many areas of the Watershed is contaminated. Many of the effects are understood and are being dealt with (such as treatment of discharges from mine tunnels). Also, groundwater that is currently being used as a drinking water source is monitored. However, significant work still remains to better understand the groundwater system and ensure any impacts are appropriately mitigated. The first step has been the compilation of the extensive amount of data and information currently available regarding local geology and groundwater. This includes past environmental investigations, U.S. Geological Survey work, past mining information, well-boring logs from around the area, and other sources. The Stakeholder Group put this information together and analyzed it for conclusions and data gaps. Future work will be evaluated.