Entrance to Argo Tunnel with accumulated sediment
The 400 square-mile Clear Creek and Idaho Springs superfund site still remains on the Environmental Protection Agency’s (EPA) superfund site list due to the levels of hazardous minerals and elements that run into Clear Creek, which acts as a water source for many of the residents in the surrounding communities. In particular, the site of old mines and mining tunnels, such as the Argo Tunnel contains a plethora of acidic metals and deposits, many of which contain zinc, arsenic, and lead (Environmental Protection Agency 2007). In addition, the Argo Tunnel was one of the primary transport systems of ore during the gold and silver crush, thus the water that drained through the tunnel was heavily toxic. Moreover, water still runs through the tunnel today, and even with current cleanup efforts, it is still rich in acidic toxins (Colorado Department of Public Health and Environment 2015).
North Clear Creek Water Treatment Plant
In order to alleviate some of the negative environmental, and ultimately health effects caused by these minerals and elements, the EPA introduced multiple remedies to help clean Clear Creek. In particular, the Argo Mine and Tunnel acted as a a major drain and ore transporting system when it was still in use during the gold and silver rush. As a result, the water that was drained through the Argo tunnel was contaminated with acidic minerals, which also bled into Clear Creek. Moreover, eighty years after the tunnel shut down, water continues to run through it thus further contaminating Clear Creek. As a result the EPA built a water treatment plant, which serves to process the sludge by removing certain chemicals from it. In addition, these chemicals are coated with lime and processed about 30 times, which has an effect of removing metals from water. In addition, the treatment plant reduces waste sent to landfills, which also helps cut down operation costs. Finally, a second plant was built in 2017 (Colorado Department of Public Health and Environment 2015).
In addition to purifying the water that flows into Clear Creek, remediation efforts included diverting the flow of water. Specifically, many of the surrounding land and rocks were also contaminated with acidic minerals, thus when it would rain, the runoff rain that would enter streams, it would also introduce those hazardous elements, thus damaging the ecosystems and animals in the surrounding areas. As a result multiple pathways to redirect the contaminated water considered, and ditches to collect the runoff water were dug (Colorado Department of Public Health and Environment 2015).
Waste rock piles that were removed in Clear Creek superfund site
The EPA also removed highly contaminated rock piles from the area. In 2010, five major rock waste piles were excavated and consolidated, along with a few minor rock piles. Other waste rock piles were recontoured, or reshaped, in order to control the flow of the contaminated water (Colorado Department of Public Health and Environment 2015).
Finally, beyond the general cleanup, the site was split into four different territories known as operable units (OU). Each operable unit contained cleanup efforts specific to that area ranging from the chemical cleanup of discharge from mining tunnels, the construction of retaining walls and the placement of vegetative covers of certain rock waste piles (Environmental Protection Agency 2021).