“The River Restores Itself” …. And Other Hopeful Messages from EPA
On August 5th, a team from EPA was investigating an abandoned mine called the Gold King, located near Durango, Colorado. The Gold King mine had been abandoned in 1923, but EPA had been investigating a leak from the mine of contaminated water. EPA was implementing a project to cap a nearby mine, which required the installation of a drainage pipe at the Gold King Mine. To do so, a worker used a backhoe to loosen material in order to install a drainage pipe. The backhoe burst through an earthen debris dam that was holding the toxic water back, causing a deluge. Water contaminated with elevated levels of arsenic and lead released into Cement Creek and then into the Animas River, which flows to navigable waters of the United States. The plume in the river has traveled to New Mexico, Utah, the southern Ute Tribe, and the Navajo Nation. The contaminated water reached Lake Powell on August 12th.
On August 5th, EPA Chief Administrator Gina McCarthy stated in a press conference, “We’re going to continue to work until this is cleaned up,” “and hold ourselves to the same standards that we would anyone that would have created this situation.” EPA has taken responsibility for the spill and has notified businesses or residents facing personal injury or property damage to file a claim for damage caused by the U.S. government actions.
On August 13th, McCarthy stated, “we are seeing the river restoring itself….” Does this mean that EPA is embracing natural attenuation or natural recovery as a response action or remediation in the Animas River? McCarthy’s statement that the river is restoring itself is intended to respond to concerns about toxic levels of lead and arsenic in the water. McCarthy clarified in her statement that EPA was in it for the long haul, which presumably means long-term remediation of any contaminated sediment remediation. Heavy metals that are part of a mine waste water discharge like this one would include arsenic, lead, copper, and cadmium, which sink and can become part of the sediments at the bottom of the river.
Monitored natural recovery (MNR) is a remedy for contaminated sediment that uses ongoing, naturally occurring processes to contain, destroy, or reduce the bioavailability or toxicity of contaminants in sediment. Not all natural processes result in risk reduction; some may increase or shift risk to other locations or receptors. According to EPA guidance, project managers could speed up natural recovery by installing flow control structures to encourage deposition, or placing a thin layer of additional clean sediment or additives to enhance sorption or chemical transformation.
Is EPA doing this in the Animas River remediation? It may be interesting for PRPs at contaminated sediment sites to follow EPA’s response actions at the Animas. Depending on the course of action selected by EPA, there could be an interesting precedent set for cleanup strategy in river environments going forward.