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SANTA FE – A persistent critic of the groundwater monitoring program at Los Alamos National Laboratory said he has found traces of what he considers “an overlooked contaminant plume” under an old waste dump on the southern boundary of the nuclear weapons laboratory.
Bob Gilkeson, an independent geologist and former contractor at the laboratory, told the Northern New Mexico Citizens Advisory Board Wednesday that he believes high levels of lead detected under an abandoned disposal area represents a threat to the regional aquifer that is “possibly larger than the chromium plume” that was discovered in the aquifer under Sandia Canyon in 2006.
“The laboratory believes that the values cited by Gilkeson are not representive of conditions at the site,” Danny Katzman, program manager of LANL’s water stewardship program said this morning.
He said a particularly high value used in Gilkeson’s evaluation was actually a non-filtered result, rather than what it was described in the database, a filtered result, and therefore was a highly misleading figure.
“That’s not a criticism of Bob, but its not a valid number,” he said, noting that the number was never repeated and that non-filtered results can be extremely unrepresentative if a large piece of corroded material has flaked off the drilling equipment.
Additionally, an analytic method used at the time, he said, applied a very strong acid that might have dissolved an unrepresentative piece of material into the sample and caused a large error.
Various laboratory reports have related that the laboratory conducted 70 explosive tests between 1959 and 1961 in four test areas on the site. The tests were designed to satisfy safety concerns about whether nuclear weapons carried on airplanes would explode in a plane crash.
The location known as MDA-AB, not far Bandelier National Monument, has been the subject of numerous investigations and activities over the years.
An official site characterization and monitoring study in 2003 said the safety experiments involved explosions in shafts that were 30 to 100 feet deep.
The inventory of radiological and metals included about 88 pounds of plutonium, 200 pounds of uranium-235, 375 pounds of uranium-238, 25 pounds of beryllium and possibly more than 200,000 pounds of lead.
Altogether, the residual material that was left in place, backfilled with sand and capped with cement, according to the report, was estimated to contain over 80 percent of the LANL’s inventory of buried transuranic material.
Transuranic (TRU) waste is composed of elements heavier than uranium.
Gilkeson’s critiques of laboratory drilling techniques and charges that the laboratory has practiced an unreliable monitoring program influenced an investigation by the National Academies of Sciences, which resulted in a detailed report on groundwater protection in 2007.
The expert committee began their section on findings and recommendations with a reference to MDA-AB.
“Solid wastes (e.g., the 25 MDAs) and certain contaminants deemed by LANL to be essentially immobile (such as plutonium) have the potential for impacting groundwater in the future. MDA AB in TA-49, which contains some 2300 (Curies of plutonium-239) is an example. The committee received little information that would provide assurance that these sources are well understood or well controlled.”
LANL reports have found little evidence that any of the radioactive materials were migrating due to water flow, although some “enhanced infiltration conditions” were attributed to an asphalt cover that was applied in 1961 and removed in 1998 on orders from the New Mexico Environment Department.
Gilkeson found particularly objectionable, a statement in a laboratory report from 2006, which said the regional aquifer at the site had been monitored by means of three deep test wells for any affects.
“In general, no effects have been found,” the document stated. “High metal concentrations (lead, zinc, iron, manganese) in samples are related to metal well casings and fittings.”
According to Gilkeson, the high levels of dissolved lead show up over a six year period, spiking at 9,000 micrograms per liter in 1993, in the well closest to the tests, 600 times higher than the national drinking water standard. Two other test wells in the vicinity but farther from the buried wastes also showed readings 5-7 times higher than the national standard during that same time.
He also looked at data from a well constructed at the same time, but 4 miles away, which he said, “never produced water with these high values.”
Gilkeson said he believes the contaminants stem not from the corroding works of the test wells, but from lead passing through the water table from that site, and if the lead is entering the aquifer, many other contaminants from the disposal area may also be getting through.
“Independent of anything that Bob (Gilkeson) has done,” we do have further studies under way at MDA-AB that has come up in the context of the Consent Order,” Katzman said, noting that additional monitoring wells are planned for the site. The Consent Order is the agreement with the state that governs the ongoing comprehensive cleanup process at Los Alamos.
Members of the advisory board, chartered to provide environmental recommendations to the Department of Energy, attempted to discuss the findings, but they were constrained by DOE’s formal representative, the Deputy Designated Federal Official Christina Houston, who said, “We don’t respond. We don’t take questions,” with reference to public comments during the meetings. She said additional input would be more appropriate through one of the board’s committees.
Ken LaGatutta, a retired physicist from LANL, was granted a request for a clarification.
One of the first to respond to Gilkeson’s written summary that was circulated last week, LaGatutta distributed an e-mail containing his own observations about “Metals in Groundwater” based on his research. Wondering if the period when high levels might have been caused by some aberration or failure in sampling or analysis, he also saw it as another unsolved groundwater mystery at the lab.
“What the heck does this mean?” he asked the board. “Is this something to worry about or not? It probably is.”