Lab struggles to sort water quality dataROGER SNODGRASS Monitor Assistant Editor
Environmental officials at Los Alamos National Laboratory focused on water quality data while updating an ongoing chromium investigation at a meeting Wednesday.
Ardyth Simmons, a program manager in water stewardship, gave an overview of the laboratory's current evaluation of its abilities to measure groundwater quality. The overall monitoring program is based on an extensive sampling program from a large number of wells, but results must be qualified according to the performance of particular wells, according to individual well screens from which samples are collected and the particular purpose of each sample.
The laboratory has gradually acknowledged that not all of the wells installed during a major effort from 1998-2005 provide reliable groundwater quality data, although they say that something useful can still be obtained from nearly every well.
Critics have been more pointed, complaining that the residual effects of drilling fluids masked key contaminants, including radionuclides, that were of greatest concern.
Officials now say that there are no simple answers, but rather a continuum of data reliability, depending on many variables. For example, wells that have a single screen for collecting samples are more reliable than wells that collect samples from multiple levels.
"Many of the screens in multi-screen levels are impacted to varying degrees by residual drilling fluids," said a bullet on one slide of Simmon's presentation. "However, nearly all multi-screen wells have at least one very reliable screen interval rated as good or very good," noted a sub-bullet.
A careful data assessment of 80 screens in 44 wells, Simmons said, concluded that 20 screens, one out of four, were very good.
But, she added, reliability in detecting some constituents of concern is much greater than for others.
In a chart from the latest assessment, the screens were 100-percent effective in detecting tritium and high explosives; 92-percent effective in providing representative data for strontium, but only half or less effective in detecting zinc, perchlorate, chromium and nitrate. The chart showed that obtaining reliable data for plutonium was the least likely (40 percent) of all the contaminants that were shown in that breakout.
Can the wells be rehabilitated? Again the answer is complicated.
In a pilot study conducted last fall, Simmons said, three deep wells that collect water quality data from the regional aquifer were redeveloped. One is considered a success; another is partially successful; a third is "not so good," she said.
A stern letter from state regulators last week warned the laboratory to pick up the pace in their groundwater monitoring program.
Simmons said that future plans are under discussion with the New Mexico Environment Department. But whether individual screens are rehabilitated, different sampling systems are installed or whole wells are replaced will depend on site evaluations currently underway.
James Bearzi, the state's Hazardous Waste Bureau chief, said after the meeting that the department continues to be concerned that the laboratory will not have an adequate monitoring system in place in time to justify a remedy selection for cleanup operations that are going on at the surface level.
"We need groundwater detection monitoring and we don't have it now," he said.
In a discussion of the chromium contamination, that has been under intensive review for the last year, Katzman said a new pair of wells will be installed close to the county's drinking water well, PM-3, to intercept signs that chromium may be approaching from upgrade where it has been detected in samples from three wells tapping into the aquifer.
Katzman said that the well drillers are using a dry air-rotary method with casing advance but without the drilling fluids that have been the subject of contention.
He said that decision had been made in the last three weeks, "in part because of discussions we have had with people."
He said drilling began on March 30, and would be completed in about two months. The first results of samples from those wells would be coming back from the laboratory by early August.