Industrial activities during the 1950s and 1960s resulted in contaminated soil and groundwater due to chlorinated solvents and other substances, leading to the closure of 20 private and two municipal water supply wells.
In 2006 and 1998 settlement agreements were reached with several responsible parties, and ONRT received total of almost $5 million for groundwater restoration.
The ONRT has identified two projects for groundwater restoration: the Mountain View Nitrate Plume Restoration Project and the Liquid Waste Groundwater Protection Project. Details about the projects can be found in the Natural Resources Restoration Plan for the South Valley Superfund Site [El Plan de Restauración de Recursos Naturales para el Sitio del Superfondo de South Valley, Albuquerque, Nuevo Mexico].
Mountain View Nitrate Plume Restoration Project [ MAP ]
ONRT is funding the cleanup of groundwater contamination that has existed for over 50 years in the Mountain View area of Albuquerque. The restoration project is designed to reduce nitrate concentrations in groundwater close to or below the State groundwater standard by using active and passive remediation technologies. The active phase will use a stepwise remediation process that employs a combination of pump-treat-discharge and enhanced bio-denitrification (EBD) technologies that are designed to reduce nitrate-contaminated groundwater within two hot spots to a concentration of approximately 40 mg/L. Upon completion of the active phase of remediation, natural attenuation will then be used to reduce the remaining nitrate contamination to the State groundwater standard (the passive phase). The two hot spots are separated by roughly 3,000 feet and, based on their locations, one is identified as the Mixing Pond Hot Spot (MPHS, the norther-most plume) and the other is the Hutchens Hot Spot (HHS, the southern-most plume). The ONRT contractor designed and implemented various field tests that resulted in the final design and construction of a EBD groundwater remediation system for the HHS (southern-most hot spot). This treatment system became operational in October 2014, it was expanded in 2016, and as of the end of December 2017, the system was successful in remediating approximately 11.5 million gallons of nitrate-contaminated groundwater. However, based on data obtained during the last couple of years, the construction of a similar EBD groundwater remediation system for the MPHS (northern-most hot spot) was found to be financially and technically unfeasible due to the following reasons: the size of the plume and nitrate concentrations have been found to be smaller and lower than initially anticipated; the aquifer is not as homogenous as expected and the impacted zone produces little water; an appropriate injection zone for the disposal of treated water could not be found; access to properties willing to accommodate the installation of an EBD system and the installation of disposal injection wells has been very difficult; and last, but not least, the budget remaining for the project is not enough to do the assessment necessary and then implement an appropriate remediation alternative that would get around the above-mentioned issues. That said, natural attenuation will be the remediation option pursued at this time for the MPHS. The New Mexico Environment Department (NMED) is providing some of the technical management and oversight of the project.
|Photos show the enhanced bio-denitrification groundwater remediation system at one of the nitrate hot spots (top photo shows above-ground structures; bottom photos show equipment and controls inside the metal building).|
Liquid Waste Groundwater Protection Project
ONRT funded the upgrade of household septic systems for qualified indigent homeowners in Sandoval, Socorro and Valencia counties. The goal was to protect groundwater quality by eliminating substandard liquid waste disposal systems. In addition to protection of groundwater, the project eliminated public health and safety hazards associated with illegal cesspools and improperly constructed septic tanks.
ONRT provided $232,000 for the implementation of this project which included funding for NMED Environmental Health Division’s oversight of the following actions:
- Proper abandonment of cesspools or other substandard on-site liquid waste disposal systems
- Installation of on-site disposal systems that meet regulatory standards
- Connection of a household to a centralized wastewater collection and treatment system if nearby service was available.
Upon completion of the project in 2013, a total of 25 household upgrades were done: 23 residences received new conventional on-site septic systems replacements (septic tanks and drain fields) and 2 residences were connected to nearby municipal sewer lines. In the process, 14 substandard septic tanks and 16 cesspools were properly emptied and abandoned from 24 residences; 1 residence had no disposal system at all.
Additional details about the Liquid Waste Groundwater Protection Project can be found in the Restoration Plan for Groundwater Protection in the Middle Rio Grande Valley.