Chrome-6 Levels Increasing in LANL Regional Well
December 14, 2007
A new study by the New Mexico Environment Department (NMED) of Los Alamos
National Laboratory (LANL) ground water data indicates that the levels of
hexavalent chromium, or chrome-6, are increasing in the regional well where
chrome-6 was first discovered in January 2004. The NMED LANL Oversight
Bureau studied the data from the regional well, R-28. The well is located
on LANL property very close to San Ildefonso Pueblo and less than a mile
from the closest drinking water well for Los Alamos County residents.
LANL is required to pump water out of the well until fresh water from the
aquifer is reached. Then sampling can begin. This is called well purging.
The standard industry practice is to purge, at a minimum, three times the
amount of stagnant water in the well before sampling.
NMED studied the purging data and the levels of chrome-6 in the well. The
NMED study revealed that in all cases LANL did not purge the well enough to
sample fresh water from the aquifer. But in most cases, LANL only purged
less than two well volumes of water. NMED found that as more water was
purged, the levels of chrome-6 increased. LANL has never properly sampled
well R-28 to understand how serious the groundwater contamination may be at
that location for chrome-6, as well as for other contaminants.
At LANL, chrome-6 was used to prevent corrosion in its steam plants, which
There are two forms of chromium, trivalent and hexavalent. The trivalent
form is beneficial to the body, but chrome-6 is toxic, even from brief
exposure. Chrome-6 is known to cause cancer and kidney and liver damage.
The New Mexico drinking water standard for chrome-6 is 50 parts per billion.
The federal Environmental Protection Agency standard is 100 parts per
In January 2004, LANL discovered chrome-6 levels of 270 parts per billion in
well R-28. Yet, they delayed in reporting the finding to NMED for almost
two years. By December 2005, the levels had increased to over 400 parts per
billion. NMED proposed a fine of nearly $800,000 for the late reporting,
which was reduced to a little over $250,000.
NMED required LANL to drill two new wells to discover the direction of the
plume between R-28 and the closest and most productive drinking water well
for Los Alamos County residents.
At first, LANL proposed to drill the wells with organic drilling fluids and
bentonite clay, which mask the detection of contaminants. Robert Gilkeson,
a registered geologist and former lead consultant to LANL's groundwater
protection program, urged LANL to drill the wells using only air in the area
of the regional aquifer. LANL did so and now states that the two wells are
Gilkeson said, "The nature and extent of the chromium plume is poorly
understood. The highest levels of contamination may be on the San Ildefonso
Pueblo land that is near well R-28. There is an immediate need to install
many more monitoring wells and to properly purge the existing wells."