Potash mining in the Carlsbad area contaminated local groundwater supplies and could be impacting the Pecos River according to findings from the New Mexico Environment Department which called for more testing and reporting from the company responsible.
To address the problem, NMED called on Mosaic Potash to revise its abatement plan – a strategy drafted by the company in April to determine the amount of contamination and strategies to fix it.
NMED required Mosaic to increase site investigations at its potash mining facilities, while include water balancing activities to study the extent of the damage and conditions of nearby areas that could become contaminated in the future.
The State also called for Mosaic to increase its reporting of permitted water wells monitored by the state.
Mosaic submitted its modified plan Oct. 20, attempting to meet NMED’s requirements, and the agency will either approve or deny the proposal within 60 days.
Here are the key takeaways from Mosaic’s latest plan to clean up groundwater contamination near Carlsbad.
What is potash? How is it mined in Carlsbad?
Potash is an ore that largely contains potassium and is used for various fertilizers.
It was first discovered in Carlsbad in 1925, and became an economic driver for the former ranching community. Potash was used in myriad products including makeup and gunpowder.
Mosaic’s mine near Carlsbad, about 16 miles east of the city on the Hobbs Highway, produces the ore through extraction when water is pumped underground and then back to the surface where the ore is then separated from the liquid.
This produces waste known as “tailings” made up of clay and salt that are moved throughout the site, stored in a “salt stack” where the waste settles and the water is pumped into a settling pond.
The resulting brine water is discharged into another pond known as Laguna Grande, sent into evaporation cells where chloride salt is harvested.
During this process, NMED found chloride and sulfate concentrations leached into groundwater and potentially the river offsite.
“Groundwater contamination between Laguna Grande and the Pecos River has been detected in groundwater monitoring wells,” read a statement from the agency. “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.”
How is the Pecos River affected? How is it monitored?
The Pecos River, a main source of surface water for the region, flows about 1.3 miles southwest of Laguna Grand, with its only continuously flowing tributary the Black River about 4 miles downstream.
“Highly mineralized” water enters the river about five miles south of Laguna Grande, largely from a brine aquifer at the Malaga Bend section of the river.
This means the water in that area of the river is already heavy with contaminants and it could be susceptible to further impacts to water quality from Mosaic’s site.
To study the extent of these impacts, the company will collect quarterly surface water samples from four locations on the Pecos.
The fourth was added in January.
“It is anticipated through this evaluation, the detailed geochemical characteristics/signatures of the individual media (groundwater, surface water, brine discharge, and natural sources of brine) will be identified and that the potential of mixing of the various media will be estimated,” read Mosaic’s proposal.
What is Mosaic’s plan to increase water monitoring?
In its revised plan, Mosaic said it would first compile all existing data on water discharges from the site, to find any gaps in the records.
Next, the plan required Mosaic to investigate the site’s geology and hydrology to determine the extent of existing contamination, along with how the contaminants migrate through water supplies.
All water wells within a 1-mile perimeter will be inventoried as part of the study, read the plan, to be used for monitoring contamination.
Mosaic will endeavor to characterize the conditions of water flowing between Laguna Grande and the Pecos River, read the plan, along with west of the Pecos River and between river and groundwater discharges from the site.
How badly does the State think the water is contaminated?
Mosaic’s present discharge permit allows for up to 7.5 million gallons per day of tailings, brine and other liquids to the salt stack, including 29,000 gallons per day of untreated domestic wastewater.
These discharges have the potential, read a report from NMED’s Ground Water Quality Bureau, to increase groundwater in the area to more than State standards for total dissolved solids (TDS), potentially impacting the Pecos River.
Should that happen, NMED has the authority to close the facility and require Mosaic provide an immediate plan to mitigate the pollution.
NMED holds a bond with Mosaic for about $82 million to fund such a closure should elevated contaminant levels be detected.
Adrian Hedden can be reached at 575-628-5516, [email protected] or @AdrianHedden on Twitter.