Water treatment system upset at the London Mine

Posted: July 24, 2018

by Save South Park

On July 16, 2018, around 4 pm a highly odiferous, alcohol-based chemical used in a water treatment process at the London Mine was discharged into Mosquito Creek bypassing the usual treatment process that would otherwise utilize the chemical in water treatment at the mine.  

Mosquito Creek before July 16, 2018 

Mosquito Creek after July 16, 2018

Minewater LLC is the operator of the treatment process. Minewater is using several innovative processes to treat the mine drainage that has been flowing into Mosquito Creek for decades. The drainage inside the Mine is comprised of two water sources, with 99% of the water flow at a pH of 8.3 (alkaline) and a very small but highly concentrated flow at pH 3 which also contains quantities of zinc and cadmium. Zinc poses ecological impacts to fish and other organisms, while cadmium is toxic to humans. Minewater’s process has reduced the zinc and cadmium loading to the creek by approximately 90% in the last 18 months. The water will be so clean it will be sold to the city of Aurora for drinking water. This is a very positive thing for the creek, its ecosystems and for the people of Aurora and those who live near and fish the creek.


Though Minewater had taken precautions to prevent any spills, the combination of a landslide in May and a broken pump caused about 100 gallons of this chemical to spill into the creek. A berm that was meant to collect any spillage was damaged by the May landslide. The operator chose to continue the treatment process even though the berm had been breached because without continuous ongoing treatment the contaminated flow of water would resume flowing into the discharge and impact the creek with more toxic heavy metals, reversing years of work.


The spill was discovered by several downstream neighbors who noticed a heavy chemical odor emanating from the creek as well as foam floating on the surface. One of the neighbors contacted MineWater who immediately began an investigation as to the source. Also alerted was the Park County Sheriff and Haz Mat Response team, the local water district manager, Colorado Parks and Wildlife, the Colorado Department of Natural resources and the Colorado Department of Public Health and the Environment Water Quality Division. After MineWater determined the source and content of the spill, Mr. Harrington as manager of Minewater also notified the appropriate regulators as well as the concerned neighbors.  He also posted information on a local Facebook site.


A team of biologists from Parks and Wildlife and the county Haz mat team were on the scene that evening to evaluate the spill and pull samples from the creek. Parks and Wildlife personnel have stated that there may be a fish kill and continue to monitor the creek. The wetlands and beaver ponds at the lower part of the creek may have absorbed most of the spill and prevented much of it from entering the Middle Fork of the South Platte, a major source of drinking water for Colorado Springs and Denver. The alcohol is used to enhance biological remediation of metals in natural and constructed wetlands so it would likely provide benefit to the wetlands community in the lower segment of Mosquito Creek.


The toxicity to neighboring wildlife is unclear. The chemical, called MicroC 3000 is a common water treatment chemical mixture used to feed bacteria and thereby remove contaminants from wastewater. While the odor of the mixture is due to very low trace amounts of higher molecular weight alcohols, the primary chemicals in the mixture are methanol and ethanol. The toxicity to humans of this mixture is lower than that of methanol alone because ethanol is the antidote to methanol toxicity.    


The president of the company who manufactures the chemical  stated that the chemical had never been directly discharged into surface waters before and so he was unsure of what effects it might have on aquatic insects, fish, and plants or on animals that might drink from the creek. He said there were no long-term effects to humans from a brief exposure and that people should remove themselves from the area of the spill.


A Haz Mat responder complained of nausea after smelling the chemical and several neighbors complained of headaches and nausea.


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