State, federal health officials prioritize cleanup efforts at Clear Creek Superfund Site

Like most of Colorado, Clear Creek County has a rich mining history. Gold was discovered near Idaho Springs in 1859. 

"For the next 20 years, the Black Hawk/Central City area was the leading mining center in Colorado," the Environmental Protection Agency stated in a Environmental Protection Agency (EPA) stated. 

Much of the state's foundation was built by that early mining activity.

But it also created some present-day hazards.

In 1983, the EPA designated the area a Superfund Cleanup Site. 

Now, after the most recent assessment showed that some of the mine waste piles may still pose a human health risk, state and federal health officials are stepping up their remediation plans. The agencies are studying what parts of the Clear Creek Superfund Site need to be prioritized for cleanup. 

Mining waste piles and "tailings" are leaking heavy metals into the watershed which ultimately provides water to millions of consumers in the Denver metro area. Lead, arsenic and cadmium are the main metals of concern in the waste piles. 

Children and pregnant women are most vulnerable to the health risks of the heavy metals. So much so, authorities suggest people who live within the Superfund Site boundaries wash their hands after gardening, don't wear their shoes indoors, and refrain from allowing children to play in areas of bare dirt. 

Parents should instead make sandboxes filled with new sand.

State and federal health agencies have identified more than 500 mining waste piles within the Superfund Site to prioritize. 

The agencies' "investigative phase" will examine mining debris in proximity to residential areas, according to a joint press release from the EPA and the Colorado Department of Public Health and Environment. The state health department's Hazardous Materials and Waste Management Division has contracted CDM Smith to assist in the investigative phase, which is expected to conclude in 2025.

The agencies stated in their press release that cleanup operations would then begin immediately after the investigative phase ended. But they also didn't rule out the possibility they would clean up waste piles prior to the phase's conclusion, particularly those with high metals concentrations which are located near residences.

The Clear Creek Superfund Site extends from the Continental Divide nearly to Golden, includes a portion of Gilpin County, and measures roughly 400 square miles. It includes the towns of Central City, Black Hawk, Idaho Springs, Empire, and Georgetown.

When gambling became legal in Central City and Black Hawk in 1992, the development of the towns spurred cleanup efforts, according to the EPA's background. 

"Construction of parking lots for the casinos capped or covered mine wastes," the website states. "Cleanup is ongoing."    

One estimate using U.S. Geological Survey data shows 1,245 known mines within Clear Creek County alone.

Some of the more significant cleanups that have already taken place since the 1983 Superfund designation include the construction of two water treatment plants. The first, completed in 1998, treats up to 700 gallons-per-minute of water from the Argo Tunnel, Big 5 Tunnel, and Virginia Canyon. 

The North Clear Creek Water Treatment Plant was completed in 2017. It treats contaminated water from the Gregory Incline, the National Tunnel and Gregory Gulch.

A storage area to manage waste rock and tailings, Church Placer Waste Rock Repository, was also created. It is located near South Willis Gulch, south of Central City. 

Site officials have scheduled four meetings with the public on July 25, July 27, August 1, and August 3. 

More information can be found by visiting the CDPHE Clear Creek website or the EPA Clear Creek website.