The Los Alamos Field Office and its contractor Los Alamos National Security (LANS) are implementing an interim measure approved by the New Mexico Environment Department (NMED) to ensure the hexavalent chromium plume stays within the laboratory’s boundary while a final remediation approach is evaluated.
Under the interim measure, one or more wells will extract the contaminated groundwater and injection wells will add the treated groundwater to the aquifer. The injection wells, which are scheduled for completion this winter, will be located along the plume periphery. Using the combination of extraction and injection, migration of the plume will be controlled.
“This approach will enable the return of millions of gallons of high-quality treated water back into the aquifer for future use,” Los Alamos Field Office Manager Doug Hintze said.
LANS and two of its drilling subcontractors installed five of the six planned injection wells. To avoid disturbing area cultural sites, three of the injection wells were drilled at an angle from existing monitoring well pad locations to reach the target location in the aquifer several hundred feet away. Those three wells were drilled with borehole lengths approximately 1,200 feet through extremely complex geologic forms, ranging from relatively soft volcanic tuff to fractured basalts and loose sand and gravel.
“While this adds complexity and cost to the drilling process, it demonstrates DOE’s and LANS’ commitment to preserving the cultural legacy of New Mexico,” said Cheryl Rodriguez, program manager with the Office of Completion Project Delivery at the Los Alamos Field Office.
Success in this campaign could allow for future angled drilling to achieve technical goals that were thought to be unachievable or entailed compromised performance due to the constraints of siting vertical wells.
The project team recently received a key discharge permit from NMED allowing for use of the injection wells.
“During 2015 and 2016, DOE and LANS worked diligently to complete the National Environmental Policy Act review and to obtain key permits that support several facets of the project,” said LANS Technical Project Lead Danny Katzman.
As the project team conducts the interim measure to control plume migration, it continues to characterize the plume center and conduct field studies to develop approaches to remediate the plume.
“It’s really exciting and rewarding to finally be tackling this contamination head-on. It’s clear why the project is such a high priority for the laboratory, and we feel that we have an excellent team and partnering environment with DOE and NMED to be successful,” said Katzman.