BY MAIRE O’NEILL
New Mexico Environment Department hydrogeologist Chris Krambis told Los Alamos County Board of Utilities Wednesday evening that the Department of Energy Environmental Management needs to focus on extraction of chromium from the hexavalent plume at Los Alamos National Laboratory.
“So far as the data shows, extraction is the favorable method to both control migration of the plume and remove mass,” Krambis said.
He also noted that the current Interim Measure being implemented by EM-LA and legacy waste contractor N3B focuses only on the top 50 to 60 feet and that the depth of the plume, which was discovered in 2005, has not yet been determined.
Krambis told the Board there have been three DOE/EM workplans under two Consent Orders that govern the Interim Measures. The first workplan was submitted in 2013 when NMED had the Lab focus first on evaluating the feasibility of pumping contaminated groundwater out of the regional aquifer to recover the contaminant mass. He said that was found to be feasible and gave birth to the first of the Interim Measure’s infrastructure wells, CrEx-1, an extraction well, which was placed in 2014 along the boundary with the Pueblo of San Ildefonso.
“At about the same time, the NMED Hazardous Waste Bureau was concerned about the potential for this plume to migrate off the Lab’s property. They noted that in their annual report it was established that groundwater could be flowing anywhere from 40 to 50 meters per year – a pretty big clip for flat hydraulic gradient,” Krambis said.
He said a second workplan was issued in 2015 and focused on control of that migration and that the Consent Order was changed somewhere around 2016. In 2017, more extraction wells and injection wells for the Interim Measure were installed and tested by the Lab.
“Then DOE submitted a third workplan that really serves to provide ways to gauge the performance through reporting and metrics over a three-year timeline. That was received in 2018. To date we have received six of these reports spanning 3 ½ years of performance of the Interim Measures. In this workplan, the whole strategy of evaluating the performance was based on an assumption that the bulk of the chromium contamination in the regional aquifer is in the top 50 to 60 feet of the regional aquifer, more or less along the water table and none of the wells penetrated much deeper than that,” Krambis said.
In reviewing the reports, Krambis said the Hazardous Waste Bureau has noticed that the assumption isn’t valid because all the wells that have been drilled since that workplan was submitted have shown that the contamination as being quite a bit deeper in certain portions of the plume. “However, the actual extent of the plume vertically remains unexplored,” he said.
“One of the key metrics to evaluate the performance of the Interim Measures is mapping the water table because it provides insight into what the Interim Measure system – extraction and injection – is actually doing and how the system operation may impact the water table and the migration of the plume and the recovery of the plume. However, there are serious technical issues with how the Lab is conducting this mapping. And we don’t see that there’s any real evidence that there’s hydraulic control along the eastern edge of that plume, where mostly it’s just focused as an injection operation and not extraction. What we have noticed are what are termed unfavorable responses in the workplan and it appears to be attributed to the injection phase of this work. And then there are other technical comments that have to be addressed by the Lab”.
Krambis went on to review DOE’s objectives for the Interim Measure. He pointed out where the strategy of the Interim Measure is focused on the top 50-60 feet of the regional aquifer.
“The principal objective is basically to reduce the concentration level at monitoring well R-50 over a three-year period to below the actual levels established by the state of 50 parts per billion (ppb) and that has largely been met well within that three-year timeline,” he said. “They reduced it from 150 ppb down to barely detectable concentrations so where did that mass really wind up? The secondary objective is to control the migration in the eastern edge of the plume and that remains to be seen.”
Using slides, Krambis showed the metrics provided by DOE to evaluate the performance over the three-year period that include concentration plots over time for various contaminants, tracer analysis to show where water is going into the aquifer from the injection wells, and water table mapping, which is a key metric to evaluate changes in gradient which would be necessary to prevent the migration from going off LANL property.
“Also mass removal estimates are a key thing and should really be more emphasized in my opinion,” Krambis said.
He showed maps that show all the wells within the chromium plume area and pointed out the Los Alamos County production well PM-3 which is located to the northeast of the plume. One map showed issues with the Interim Measures superimposed on it.
Krambis discussed a 2017 in-situ pilot study that involved the injection of molasses into monitoring well R-28 and sodium dithionite into monitoring well R-42 to evaluate if they could change the chemistry of the aquifer to reduce and precipitate the chromium out. He said neither of these two wells have been used for monitoring since 2017 and it has been agreed to replace R-28 and possibly R-42, pending further testing.
“This line of injection wells should be doing something to stop migration and we don’t see evidence of that,” he said.
What is being seen in performance monitoring wells R-61 and R-45 are what are termed “unfavorable responses”, Krambis said.
“It looks like the injection operation is not doing what was hoped. However, the shining star is the extraction specifically at Extraction Wells 2 and 4, and it’s doing very well. It’s drawing down the water table and providing for removal of the chromium mass quite effectively,” he said.
Krambis noted that it’s really in the central area of the plume that almost 100 pounds of chromium is removed per year by the extraction wells.
“It would be good to really focus on that more. Also, it definitely stops migration because all the water along the water table will flow into this circle. That’s a really positive thing I think should be focused on in the future,” he said.
Krambis noted on the maps the “circle” where effective capture by pumping water out is being seen.
“But we don’t see that injection here is really doing what was hoped, which was creating a barrier to further [continued] migration. This is just along the water table. A lot of these wells have deeper screens so when you map the deeper water levels or heads as we call them at the same time the system is running the same way, we see no effects of pumping whether it’s extraction or injection at all on water table contours down at depth,” he said. “The assumption was earlier that a lot of this mass – they only focused on the top 50 or 60 feet – isn’t being sufficiently addressed by the interim measures for this center area all the way out to R-70 where we know contamination is deeper. These water levels probably reflect depths of between 70 and 100 feet below the water table so the Interim Measure as it’s designed and implemented now, would do nothing to control the migration at depth.”
Krambis said after the three-year evaluation period, NMED believes it’s to reevaluate the strategy with a new workplan to refocus the Interim Measure to achieve its goal in accordance with the consent order.
“This workplan is Milestone 2 for this year, which will be received at the end of September, and we’re expecting the Interim Measure will provide flexibility for adjustments to the system as needed, focus on the extraction, which so far the data shows is the favorable method to both control the migration and to remove mass which would encompass the two first workplans,” he said.
Krambis said Injection issues will have to be addressed and some modeling input would be needed. It would also be necessary to deal with the entire thickness of the plume, not just the top 50-60 feet.
“We don’t know how deep it is. It’s at least 100 feet down. We need better metrics for performance evaluation because like I said, R-50 – the objective has been met – but we don’t know what it means. Did the injected water just push that material towards R-61? Was it recovered? We need better metrics and we need to start to move forward towards corrective measures,” he said.
Asked if only 100 pounds of chromium is being pulled out per year, what the total amount is that needs to be cleaned up, Krambis said the total amount that was believed to have been released at the one cooling tower was 160,000 pounds.
“A lot of that mass is locked up in the wetlands. Some is still in the perched aquifer which is a pretty discontinuous, and the rest is in the regional aquifer. So I don’t know that they ever estimated the actual mass in the regional aquifer. They should do that though,” Krambis said.
Asked where the water being used for the injection process comes from, Krambis explained that it comes from the extraction wells.
“When they pull the water out of the extraction wells, they treat it with an ion exchange and then they take that water and inject it into the five injection wells,” he said.
One board member said it concerns him, and always has, that the contamination issue has been there since 2005 and it has taken more than a decade to really think about extracting the plume.
“The PM-3 water comes into White Rock and I’m concerned about that and always have been. I guess I’m a little disappointed that the state hasn’t pushed the Lab frankly to characterize this a little better and not leave so many open-ended questions for so long without presenting any kind of a justification to the public,” he said.
“We’re kind of at the end of the evaluation period for the Interim Measure and I don’t’ think we’re too happy about the slow progress but we are working with the Lab within the confines of the Consent Order. And so we have to work in that manner, at least the Hazardous Waste Bureau does,” Krambis responded. “We are trying to get things into a more defensible approach. I think we’re moving in the right direction. We are getting DOE to provide some more plans to drill some new monitoring wells, to further evaluate what this plume is doing and how deep it is, and hopefully with the new workplan for the Interim Measure we can get it into a condition where it is far more effective and will lead to the Corrective Measures in the not so distant future.”
Krambis was also asked if NMED is constrained in what they can require the Lab to do as far as cleanup through the regulatory process.
“Pretty much there is a consensus I think that it has to be remediated. Whether it’s going offsite or not, it has to be remediated in a proactive manner. They tried two approaches, the geochemical approach which didn’t quite work out and then this Interim Measure is really a pump and treat approach, so we’re not at a consensus as to what’s the best approach. The Interim Measure is looking like it’s emphasizing pump and treat extraction specifically. I don’t think it matters regulatorily whether it’s going off the LANL property or not – I think that’s the whole point of the Interim Measure is to stop that,” he said.
Asked when the plume might reach the County’s production well PM-3, Krambis responded, “We don’t know enough to determine when it would get to PM-3. That’s what we’re trying to get them to evaluate”.
Asked if he has an idea of what a better Interim Measure would be, Krambis said, “Absolutely – turn all the injection wells into extraction wells and we’ll have to figure out what to do with the treated water but I think extraction and treatment at the surface and treated to a way that maybe the Lab can use that water instead of injecting it. I think injecting the water is causing some undesirable effects. Hopefully they would just focus on extraction”.
Los Alamos County’s Public Utilities Manager Philo Shelton said Thursday that he looks forward to having a new well drilled to give us “new data that will help determine the nature, extent, and depth of the chromium plume”
DOE/EM-LA Manager Michael Mikolanis said Friday morning that EM-LA is aware of NMED’s technical perspectives on the chromium Interim Measure perfomance.
“While we have differing professional opinions on a relatively small number of conclusions that have been drawn, we continue to work collaboratively with the state of New Mexico to evaluate and model the dataset already collected,” he said. “We will consider if adjustments to Chromium Interim operations are warranted and whether additional wells should be installed. This evaluation will enable us to progress to a final remedy.”
Mikolanis added that nearby water-supply wells—which are regularly monitored—remain unaffected by the plume”.
The Board of Public Utilities is expected to hear a presentation on the chromium plume during their Mar. 2 meeting from Danny Katzman, groundwater remediation program manager for Tech2 Solutions, a subcontractor to N2B’s Water Program. N3B is the legacy waste cleanup contractor for EM-LA.
For more information on the chromium plume, see the Reporter’s 2019 article here: https://losalamosreporter.com/2019/05/30/chromium-interim-measure-in-full-swing-in-mortendad-canyon/