The New Mexico Environment Department (NMED) reported on April 15 that it is reviewing a Stage 1 Abatement Plan (Plan) to investigate and define the extent of groundwater contamination from discharges associated with potash mining.
Groundwater contamination between Laguna Grande, a naturally occurring salt lake, and the Pecos River has been detected in groundwater monitoring wells. As a result, NMED required Mosaic Potash Carlsbad to submit the Plan to characterize the nature and extent of groundwater contamination from mine discharges between Laguna Grande and the Pecos River.
Mosaic operates a potash mine located approximately 16 miles east of Carlsbad in Eddy County, N.M. The mine includes both an underground potash mine and surface mill that produces potash products. The mill produces potash tailings that are discharged to an onsite salt stack, where coarse salt and clay settle.
Under normal operating conditions, brine water and residual clay flow off the stack and discharge to a clay settling pond. The brine water in the pond is discharged through a brine pipeline to the northern end of Laguna Grande. The brine in Laguna Grande is diverted into a series of evaporation cells operated by United Salt and New Mexico Salt for chloride salt harvesting.
NMED approved the first discharge plan and issued the first discharge permit (DP-1399) for Mosaic in 2004, with subsequent renewal in 2011. DP-1399 is currently in effect and addresses all site discharges. It is in the process of being renewed.
The Plan includes a summary of site conditions, including site history and previously conducted investigations, and proposes steps to define the nature and extent of groundwater contamination. NMED will review the Plan and either approve it or send Mosaic a Notification of Deficiency within 60 days.
Once Mosaic completes the site characterization and NMED approves the Final Site Characterization Report, NMED may require a Stage 2 Abatement Plan that outlines strategies to clean up the groundwater contamination.