Untreated water spills into river
The evil twins of human error and a mechanical malfunction combined to cause 92,700 gallons of partially treated and contaminated water from the Eagle Mine to leak from a treatment plant into the Eagle River.
No visible biological impacts from last week’s spill have been reported, but
it’s the second incident at the automated treatment plant near Minturn this year. The first accident, in January, was mechanical and involved just 300 gallons of untreated water and did not result in the release of water into the Eagle River. The second, larger spill, occurred in the early-morning hours of Oct. 9 at the unattended plant.
That spill of partially treated water occurred between 1:46 a.m. and 6:46 a.m. and is slightly more in volume than that contained in three, 30,000 gallon, semi-tank trucks.
Preliminary lab results of water sampled immediately after the spill – released Friday by the contractor for the water plant – contained approximately one-third more zinc than is allowed. The state allows 1.5 parts per-million of zinc and at the height of the spill, those levels approached 2.1 parts per-million.
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While the incident may not have created immediate visible impacts, it could have an impact later on.
“Any time the metal levels go up it can have an impact on the sensitive bug and fish populations,” said Joe Macy, president of the watchdog Eagle River Watershed Council. “We just can’t know for certain what those impacts might be.”
Plant operator Frank Environmental Services of Springfield, Ill., notified the Colorado Department of Public Health and Environment by telephone immediately after the discharge and later outlined what happened in a letter to the state, as required by law.
The leak of partially treated water happened when an employee of the plant forgot to flip a switch that turns on the automatic system before heading home at the end of his shift. That switch also powers an automatic telephone notification system that alerts the operator to problems at the automated plant.
Later, an electrically powered conveyor belt that supplies lime to the treatment plant overloaded, causing an electrical breaker to trip, shutting down the treatment process.
“We operate the plant 365 days a year for three years,” said Jim Frank, owner of Frank Environmental Services. “On one of those 1,000 days we forgot to flip a switch.”
Frank said the raw water from the mine contains as much as 40 parts of zinc per-million, but once it’s treated at the plant, it routinely has a level one one-hundredth of that.
The water from the defunct Eagle Mine, which issues from springs and natural seeps in its 75 miles of underground tunnels, is acidic and contains a significant concentration of dissolved iron and lesser amounts of manganese, zinc and trace amounts of heavy metals. The water is piped from the mine to the treatment plant just south of Minturn.
The treatment plant removes the metals and releases pure water into the river. The spill did not result in any fish kills and did not require the water plant in Avon to change its operation, said Dennis Gelvin, general manager of the Eagle River Water and Sanitation District.
The flow of the river through Minturn at the time of the spill was approximately 35 cubic feet per-second, or 15,715 gallons per-second. The discharge rate was 309 gallons per-minute for approximately five hours.
The mine water treatment plant is one of the holdovers from the cleanup embarked upon after the shutdown of the Eagle Mine in 1984. When the mine was closed, treatment of the mine water and mine tailings ceased and untreated, metals-laden water killed all aquatic life in the seven miles of river between the mine and confluence with Gore Creek at Dowd Junction.
Since then, mine owner Viacom has spent $70 million cleaning up the river under a 1992 agreement with the U.S. Environmental Protection Agency and the Colorado Department of Public Health and Environment. The mine water treatment plant is expected to operate in perpetuity.
Typically when the plant is unattended, if there is a problem, or an operator cannot be reached, the computer shuts down the plant and diverts the untreated water to an on-site holding pond. This time, it didn’t happen because the switch hadn’t been flipped.
Once the malfunctioning systems were noted, the operator shut down the plant and diverted the untreated water into a holding pond. The plant was restarted and was operating properly by early afternoon.
The plant was converted three years ago from around-the-clock staffing to automation. It has a single operator on shift, Monday through Fridays.
“We operate plants (like this) at other parts of the country and we have computerized all our plants,” Frank said. “We get much better results from computerized operations than from manned operations.”
Since the active phase of the cleanup of the mine ceased two years ago, the water quality of the river had improved significantly, as recorded in regular sampling and fish counts.
As a result of the spill, Frank said the company is reprogramming the plant’s computer to automatically flip its own switch at the end of manned shifts, eliminating the human error factor. Frank also said an electrician is examining the operation to determine why the electrical breaker tripped.
A third, much simpler safeguard is also being installed: signs reminding employees to be sure the computer is in the right mode before they leave the plant.
Cliff Thompson can be reached at 970-949-0555 x450 or firstname.lastname@example.org