MCGAFFEY AND MAIN GROUNDWATER PLUME
On this page:
- What Is Being Done to Clean Up the Site?
- What Is the Current Site Status?
- EPA’s Involvement at the Site
On related pages:
The 550-acre McGaffey and Main Groundwater Plume site is located in Roswell, New Mexico. The site includes locations where several dry cleaners operated from 1956 to 1963. These operations contaminated groundwater with perchloroethylene (PCE).
What Is Being Done to Clean Up the Site?
The site is being addressed through state and federal actions.
What Is the Current Site Status?
The Record of Decision (ROD), which documents the preferred selected remedy, was issued on September 30, 2008. The ROD selected a multi-component remedy employing a phased implementation approach. The remedy included: 1) Source Area Soil and Indoor Air (vapor mitigation systems at six commercial buildings and soil excavation with a contingency for soil vapor extraction [SVE]), 2) Source Area Groundwater (pump, pretreat, and discharge to the Roswell publically-owned treatment works [POTW]), and 3) Groundwater Plume (pump and discharge to Roswell POTW for treatment, and enhanced reductive dechlorinated [ERD] for plume hot spot area).
EPA completed the remedial design (RD) phase for construction of VIMS and SVE in 2011. Construction completion of VIMS and SVE was achieved in September 2012. The PCE concentration in the VIMS influent piped to a central treatment facility decreased from 72,000 micrograms per cubic meter (ug/m3) immediately after VIMS start up in December 2012 to 12.7 ug/m3 in April 2014. A total of 430 pounds of PCE are estimated to have been removed by the combined VIMS and SVE technologies to-date.
The New Mexico Environmental Department (NMED) performs remedial design investigations for the groundwater plume and hot spot areas. In September 2013, NMED completed the ERD RD for the hot spot area of the plume. NMED also initiated the RA at the hot spot in May 2014; 30 monitoring and injection wells were installed. However, no amendment injections have been delivered yet. The EPA and NMED are currently collaborating on finding ways to optimize the remedy, pertaining to addressing the source area groundwater PCE contamination and the broader groundwater plume, with the assistance of an EPA Optimization Team.
Shutdown of VIMS was implemented for 12 months (April 2015 to April 2016), and no adverse indoor air impacts have been observed. There were no detections of PCE in the indoor air rebound samples that exceeded the current EPA regional screening level of 11 micrograms per cubic meter during the 12-month VIMS shutdown period. The VIMS rebound test was performed to evaluate whether the SVE system alone can effectively intercept enough of the vapor intrusion pathway to protect indoor air. Throughout the April 2015 through April 2016 period,, while the VIMS was shutdown, the indoor air RSL for PCE was not exceeded in any of the samples collected from the VIMS-equipped buildings. The primary conclusion from the VIMS rebound test is that the SVE remedy appears to be effectively controlling the vapor intrusion pathway when operated in a continuous mode. Transition of the SVE system from continuous to pulsed operations represents a logical progression for the SVE remedy. However, this transition will be implemented cautiously, such that the vapor intrusion pathway remains controlled.
The EPA is also currently working on the Source Area groundwater RD. A task order for RD and engineering services was modified and reissued in June 2016. The objective of the groundwater remedy is to emphasize source control or capture and treatment of high PCE concentration groundwater, rather than aquifer restoration, using a single, existing extraction well. Source control is expected to abate expansion of the plume’s leading edge into areas where alluvial aquifer groundwater is beneficially used. The RD is expected to be completed by late spring 2017.
EPA’s Involvement at the Site
The site spans about 550 acres and lies within a commercial and residential area where several dry cleaning businesses operated from 1956 to 1963. The site consists of a groundwater plume that extends about two miles southeast from the intersection of South Main Street and McGaffey Street.