By Cassie McClure
Published in the Las Cruces Bulletin 10.15.2021
Many residents routinely visit the Harty Athletic Complex, the BMX bike track, or the skate park off Hadley Avenue. Maybe a few have wondered what is beyond the recreational areas, the building on the hill with two tanks. For those curious, those tanks are attached to the co-owned City of Las Cruces and Dona Ana County Griggs-Walnut Groundwater Plume Superfund remediation project, which is operated and managed by Las Cruces Utilities. The project just completed its 9th Anniversary, where visitors could come out to an open house to see how LCU cleans contaminated groundwater daily.
The water treatment facility clears the groundwater of the chemical perchloroethylene — commonly referred to as PCE — to make the water drinkable. PCE is a manufactured chemical used for dry cleaning clothes and degreasing metal and was first detected in Las Cruces groundwater in 1993. The affected water wells were immediately taken offline.
In June 2011, both the Las Cruces City Council and the Doña Ana Board of County Commissioners approved the Environmental Protection Agency’s Modified Administrative Order and provided an intent to comply with the EPA. The action allowed for the construction of a water treatment facility which processes more than 350,000 gallons of water per day, removing the PCE and making the water suitable for drinking.
“Due to the efficiency of the project, the upper portion of the PCE plume has decreased in such a manner that the pumping regime for Well 18 has been modified from pumping 8 hours per day at 90 gallons per minute to 6 hours per day at 88 gallons per minute for two days per week,” said LCU Assistant Utilities Director Adrienne L. Widmer, P.E. “This allows the treatment system to treat water that is above the maximum contaminant level instead of treating water below regulatory levels.”
Multiple monitoring wells are used for sampling, analyses, and current mapping locations of the PCE plume annually. Earlier in January 2021, older monitoring wells were rehabilitated.
“I had an intensive tour of the facility about a year ago shortly after I joined the commission, but I was interested to see the progress a year later in further reducing the contaminants,” said LCU Board of Commissioners member Dr. Harry Hardee. “It is a very well run facility, but the average citizen probably knows nothing about the facility or purpose.”
The contaminated groundwater is pumped from two offline municipal wells — No. 18 and No. 27 — and passes through air strippers that expose the impacted water to oxygen, which dissipates the PCE, removing it from the water. Chlorine is then added to the treated water before being transferred to the Upper Griggs Reservoir, off Triviz Drive, and distributed for consumption.
LCU Customer Central can be reached at 575-541-2111 from 8 a.m. - 6 p.m. Monday through Friday. LCU provides clean, safe, and reliable services to Las Cruces residents and businesses. Learn more at: las-cruces.org/180/Utilities For emergencies, call Dispatch at 526-0500.
PHOTO 1: LCU Water Production Operator Jacob Cabrales explains to visitors how the Griggs-Walnut Groundwater Plume Remediation Project works to clean PCEs from contaminated groundwater.