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LANL to start work on abandoned wells

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Plan calls for filling, capping of old testing wells near chromium plume; work to start in June

By Tris DeRoma

Plans are underway by the Los Alamos National Laboratory to head off a potential threat to an aquifer that lies mostly under Mortandad Canyon.

The plans call for the  filling and capping of 26 abandoned testing wells in Los Alamos Canyon, Sandia Canyon, Mortandad Canyon, Pajarito Canyon and Tech Area 35. 

The wells were drilled in from the mid-1960s to the mid-1980s. Most of the wells were drilled to test for contaminants in the water and soil.

Some of the wells sit near known sources of contamination the lab is remediating. By filling and capping the wells, LANL seeks to prevent any further contamination to the area.

“These wells are now over 40 years old and most are no longer used,” according to a report on the wells in Los Alamos Canyon. “Because these wells may provide a pathway for contamination to move to the alluvial and perched groundwater, the unused wells should be plugged and abandoned.”

Depths vary from 12 feet to 120 feet and their diameters varied between two and six inches.

LANL has submitted five plans to the New Mexico Environment Department on how its contractors will proceed. The first step of the plan is to conduct field work this June to see what’s going to be involved.

“Field reconnaissance will be conducted at the wells and boreholes to verify field conditions and construction details of each well,” said the report.

Part of the problem is at least on some of the wells and boreholes, they don’t know how deep they go. Existence of some of the wells was not known till recently.

“The well, labeled PCM-2a, close to PCM-2, was located while looking for other wells. It has not been found in any Laboratory literature or well and borehole databases. Therefore, its purpose and the construction are not known, other than it is 18 (feet) deep and 2 (inches) in diameter,” the report said of a well recently discovered while contractors were performing other work out on the Pajarito Plateau.

A more detailed report documenting each state of the well will be submitted to the NMED by LANL by March 30, 2018.
LANL’s proposed plan of attack includes taking out the well casing and screens and then backfill it with either a bentonite grout, cement, or concrete.

Field work in June will consist of draining the abandoned wells of standing water. If they fill again, tests will be made of the water to see what contaminants may be in them.

Toxic runoff from lab activities through the years have found their way into the canyons.

Mortandad Canyon is the site of a chromium plume that was discovered in 2005.

Contractors for the lab are in the process of cleaning and halting the spread of the chromium plume in Mortandad Canyon.

The chromium plume, which is located deep in the canyon’s soil, is being cleaned through a network of injection and treatment wells designed to stop and prevent its spreading.

The plume was discovered in 2005. Between 1956 and 1972 LANL flushed water and chromium (an anti-corrosive) through cooling towers located in Sandia Canyon. The chromium eventually found its way into the Mortandad aquifer.

A 2006 study prepared by the Concerned Citizens for Nuclear Safety and Amigos Bravos identified at 1,405 sites contaminated by LANL waste found in stormwater runoff, including the canyons the wells are located in.