The Laboratory has completed a detailed Resource Conservation and Recovery Act Facility Investigation at a site along DP Road where petroleum products historically were stored. The site, known as DP Tank Farm, is located near the intersection of DP Road and Trinity Drive in Los Alamos. The investigation was conducted in accordance with the requirements of the Laboratory's RCRA Hazardous Waste Facility Permit. The RFI led to a recommendation to the New Mexico Environment Department, and NMED's concurrence, that the site required no further cleanup action.
DP Tank Farm was the primary fuel-storage area supporting Laboratory operations from January 1946 to February 1988 and consisted of two fill stations and 15 petroleum-product storage tanks. Day-to-day operations at the site resulted in the release of small amounts of diesel fuel and gasoline into the environment, including petroleum hydrocarbons seeps - a trickle from a fracture, in DP Canyon. Over the years, the petroleum hydrocarbons have migrated slowly through the tuff and along rock fractures and clay beds a few feet below the surface.
"Our investigation was conducted in phases over the last several years," said John Hopkins of Remediation (RRES-R) and the Laboratory's project leader. During the initial phase of work, the tanks; piping; and all related equipment were removed, along with some contaminated soils. During the RFI, numerous samples were collected to locate and then characterize the location of the traces of residual contamination at the site.
"During the second phase of the RFI, conducted from April 2000 through July 2001, the former tank farm and two related petroleum hydrocarbon seeps in DP Canyon were investigated. Our investigations were conducted in accordance with RCRA corrective action and New Mexico Environment Department underground storage tank requirements, " said Hopkins. A total of 179 samples were collected, including sediment from DP Canyon and subsurface soil and tuff from the mesa top portion of the site. The data were used to fill information gaps remaining after previous investigations. The samples were submitted to an off-site contract laboratory and analyzed for a variety of contaminants, including total petroleum hydrocarbons, both volatile and semi-volatile organic compounds, and lead present in leaded gasoline previously stored at the site.
Laboratory scientists confirmed that no bulk sources of contamination or subsurface structures remained at the site; confirmed the nature and extent of the traces of residual hydrocarbon contamination still present; identified the source of the two petroleum hydrocarbon seeps; and performed a risk assessment of the traces of residual hydrocarbon contamination in the subsurface beneath the mesa top, which were found not to pose an unacceptable risk to human health or the environment.
Regular inspections of the hydrocarbon seeps are conducted to document any changes in relation to seasonal changes and precipitation. The Laboratory prepared and submitted a Phase II RFI report to the New Mexico Environment Department recommending no further action for the site. The NMED approved the Phase II RFI Report for DP Tank Farm Jan. 14 and will remove this site from the Laboratory's permit when the NMED approves a permit modification later this year. The property is scheduled to be transferred from the Department of Energy to Los Alamos County this September.
