Challenge

Activities at a former business in Jarales, New Mexico, Midway Grocery, had caused widespread petroleum contamination in soil and groundwater on and surrounding the site. The New Mexico Environmental Department (NMED) Petroleum Storage Tank Bureau (PSTB) was aware of one buried storage tank on site but needed assistance in characterizing the full extent of contamination.

Solutions

The NMED PSTB contracted GLA to perform remediation services on the contaminated soil. Our team first prepared a Final Remediation Plan with detailed corrective actions for the site. Before any on-site remedial measures, we first completed community outreach to explain the remediation approach and schedule, taking all necessary measures to ensure surrounding property owners and personnel at a nearby elementary school were protected from exposure to potential petroleum vapors.

GLA conducted and completed several remedial activities at the site, including soil flushing, excavation dewatering, soil excavation, disposal, and backfill, excavation of three on-site septic tanks, indoor air quality assessment, vapor mitigation system installation, monitor well installation, and site restoration. GLA performed field screening of soils using a photoionization detector to assist in delineation of horizontal and vertical contaminant impacts before removing, safely disposing of, and replacing the contaminated soil. During soil excavation, 25,600 gallons of groundwater were extracted, treated with hydrogen peroxide, and recharged through a temporary subsurface recharge pipe that was installed on the upgradient side of the property. Lastly, vapor mitigation trenches were installed along two edges of the abandoned Midway Grocery building. Perforated HDPE pipe and gravel were placed in the trench, and blowers were connected to the pipe to discharge vapers approximately five feet above the building roof line.

Results

Our remedial activities successfully reduced contamination in all contaminated aspects of the site and surrounding areas. GLA’s excavation activities resulted in the replacement of 4,800 cubic yards of petroleum-contaminated soil and septic tank debris with clean backfill. Sampling of the vapor emissions indicated levels below regulatory limits, and a No Permit Required determination was obtained from the NMED Air Quality Bureau for operation of the vapor mitigation system. The most recent indoor air quality sampling event showed a large reduction in petroleum hydrocarbons in indoor air. Further, the most recent groundwater samples collected from site indicate only relative minor levels of contaminants remain, with dissolved phase contaminants above standards in only two of ten monitor wells.