Officials provide chromium update

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Water meets standards, but officials uncertain of plume boundary location

By Tris DeRoma

County officials and officials from the Department of Energy’s Environmental Management, Los Alamos Field Office told county officials during a Jan. 9 presentation that a chromium plume under Mortandad Canyon does not pose a threat to Los Alamos County’s drinking water supply.


Four drinking water wells closest to the chromium plume are tested quarterly, according to Department of Public Utility officials.

“As of yet, we have seen nothing  above background in any of those wells,” Los Alamos DPU Manager Tim Glasco told the council.

Glasco also said that even before 2005, for at least 25 years, the DPU has had a cooperative agreement with the Los Alamos National Laboratory and the Department of Energy to test all of the drinking wells annually.

“We meet all federal and state drinking water standards. So, by definition, our drinking water supply is safe,” Glasco said.

The Environmental Protection Agency defines a part in this case as one drop of water in 1 billion drops of water, about what an average swimming pool contains. The acceptable state limit for chromium is 50 parts per billion. The federal standard is 100 parts per billion.

According to Glasco, the contamination is about a quarter of a mile from the nearest well. There is also 700 feet of rock and soil between the underground plume and the aquifer.

The chromium deposit was formed when a nearby power plant drained cooling water from its cooling towers into the canyon from 1956 to 1972. The chromium, known as chromium 6, was used as a pipe corrosion inhibitor. It is harmful to humans.

The plume, which is about 1 mile long, half a mile wide and 50-feet deep, sits over a layer of rock over a regional aquifer the county draws drinking water from. Ever since the discovery of the plume in 2005, county, state and federal agencies have been monitoring the chromium levels in the drinking water every year.

Since 2002, the highest levels of chromium seen in testing are 12 parts per billion, which Glasco said occurs during natural variations of sampling. The lowest they’ve seen is four parts per billion.

Since 2005, LANL has set up a network of injection and treatment wells around that control the spread of the plume until a permanent solution is realized.

Glasco said if any type of increase of chromium is detected beyond the usual variations, they will shut down the affected well immediately. He noted that there are monitoring wells between the plume and the nearest drinking water wells that are designed to detect increasing levels of chromium before it reaches the wells.

“If we start to see any type of movement in the chromium level in the (drinking water well) we will also request we up that sampling frequency until we have determined that it is not just a natural variation in data, but is a trend of upward concentrations of chromium,” Glasco said. “At that point, we will look at environmental conditions, what rate is this going up, how close are we to the drinking water standard, how close are we to the other drinking water standards.”

Glasco said most likely in a situation like that they would shut it down and rely on the other remaining wells.
Los Alamos County Vice Chair Chris Chandler wanted to know about the well the department is currently drilling, and if its going to tap the same aquifer all the others are.

Glasco said yes, it’s the same aquifer.

“So we’re in a pickle,” Chandler said.

Glasco assured Chandler that because of the geological conditions surrounding the aquifer, “we don’t expect to see any type of contamination from this contamination plume probably ever. If we did, we’d be very surprised,” Glasco said. “If we did, it would probably be decades out, based on what we know about this aquifer.”

Doug Hintze, field manager for the DOE’s Los Alamos Environmental Management office told council that data shows the plume is moving horizontally, but not vertically toward the aquifer. He also said during his part of the presentation that the DOE expects to come up with a permanent solution that removes all the chromium 6 plume long before then.
Chandler had questions about the plume’s horizontal movement, and if the DOE knows the true boundaries of the plume. One of the DOE’s priorities is to stop the plume’s spread onto the San Ildefonso Pueblo.

“On the boundary close to the San Ildefonso, where the plume suddenly stops right at the boundary… I was kind of curious about that. That’s a very smart plume. How confident are you that it hasn’t gone into the pueblo area.”
Hintze said the monitoring well placed on San Ildefonso land does not show any chromium above background levels.
“But, we don’t know exactly where it (chromium plume boundary) is, you’re exactly right,” Hintze said.