BNL’s enhanced groundwater monitoring program has detected common petroleum hydrocarbon (oil or gasoline) products and a degreasing solvent at levels above New York State water quality standards near its onsite commercial automobile service station (BNL Building 630). The exact source has not been confirmed yet, but it is suspected that the contamination is attributable to historical surface spillage.

BNL has formed a technical team to identify the source of the contamination. Procedures and processes at the Service Station, which were originally reviewed as part of the EPA Phase II Process Evaluation Project, will be further reviewed as appropriate. BNL will take corrective measures as necessary to prevent any further potential releases of these chemicals.

Recent groundwater monitoring has also indicated that carbon tetrachloride contamination associated with a nearby tank removal has also impacted groundwater quality in the Service Station area. Groundwater in the carbon tetrachloride spill area is currently being treated as part of BNL’s Environmental Restoration program. Evaluating the nature and extent of contamination in these two areas is being coordinated.

This contamination will not impact BNL’s potable water supply.

• BNL's Environmental Management System includes a comprehensive groundwater protection program that relies primarily on pollution prevention--using operational and engineered controls to prevent contamination from entering the groundwater. Since the BNL is situated above a sole source aquifer, is it a priority for the Laboratory to protect this resource.
• A supporting element of the groundwater protection program is the monitoring program. The monitoring program is used to determine whether or not operational controls and treatment systems are effective and whether there are other problems that need to be addressed. There are over 700 monitoring wells onsite -- most of which are associated with the Environmental Restoration program, and others which monitor water quality near active research and support facilities.
• As part of the BNL Groundwater Monitoring Improvements Project, 84 new wells were installed near active research and support operations across the Laboratory during 1999 and early 2000. BNL expected that these wells would detect some contaminants from historic practices, and is using the monitoring data to help determine what corrective actions may be needed, and whether the corrective actions are effective.

• The Service Station has been in operation since 1966. In addition to storing and dispensing petroleum products, the Service Station also does parts degreasing associated with automobile maintenance.
• The Service Station is located near the center of the BNL property, approximately one mile from the BNL southern boundary.
• The Service Station’s underground storage tanks and associated piping systems conform with Suffolk County Article 12 requirements. The tanks and piping systems were upgraded in 1989. No indications of soil contamination were noted at the time of tank replacement.
• Although the Service Station was originally constructed with floor drains in the automotive bay areas, these drains emptied into an oil/water separator prior to discharge to BNL’s main sanitary system. The drains were sealed in 1990.
• The closest BNL drinking water supply well is located several thousand feet northwest (upgradient) of these source areas.
• In April 1998, BNL removed an underground storage tank from an area approximately 200 feet to the west of the Service Station. The tank was used to store carbon tetrachloride as part of an experiment conducted in the 1950s. Carbon tetrachloride remaining in the tank was inadvertently released during the excavation and removal process. Groundwater impacted by the carbon tetrachloride release is being monitored and treated under the Environmental Restoration program.

• In 1997, BNL installed two monitoring wells in the Service Station area to evaluate general groundwater quality downgradient of the facility (Wells 085-16 and 085-17). Initial monitoring results indicated the presence of low levels of volatile organic compounds (VOCs). The solvent tetrachloroethylene and carbon tetrachloride, and the fuel additive MTBE were detected at concentrations of < 20 micrograms per liter (ug/L). The New York State Ambient Water Quality Standard for most VOCs is 5 ug/L; the standard for MTBE is 50 ug/L.

• In 1998 a groundwater monitoring program was established in the area impacted by carbon tetrachloride released during tank removal (described above). To mitigate the carbon tetrachloride release, groundwater in the former underground tank area has been undergoing active remediation since October 6, 1999 as part of BNL’s Environmental Restoration program (OU III – Carbon Tetrachloride Plume Removal Project).
• In January 2000, three new wells (085-235, 085-236 and 085-237) were installed at the Service Station to gather additional information on the quality of groundwater in this area (see Attachment 1).
• In late February 2000, BNL received initial analytical results for groundwater samples collected from the enhanced monitoring well network. High levels of carbon tetrachloride (up to 2,140 m g/L) and petroleum hydrocarbon-related compounds were detected in several wells (see Attachment 2).
• The wells were immediately resampled in late February. Results from these samples, and subsequent samples collected in March and April confirmed the initial results (Attachments 3, 4 and 5). However, samples collected in June had significantly lower concentrations of petroleum hydrocarbon-related compounds (Attachment 6).
• High levels of carbon tetrachloride have been detected in wells located both upgradient and downgradient of the Service Station, and can be traced to releases at the former underground storage tank area to the west (see carbon tetrachloride plume map in Attachment 7).
• The petroleum hydrocarbon-related chemicals, on the other hand, are only found in Wells 085-236 and 085-237, located downgradient of the Service Station. Therefore, these contaminants are related to releases from this facility.
• Primary petroleum hydrocarbon contaminants detected in samples collected during February-May include xylenes (up to 420 ug/L), ethylbenzene (up to 77 ug/L), 1,2,4-trimethylbenzene (up to 47 ug/L), 1,3,5-Trimethylbenzene (up to 31 ug/L), and naphthalene (up to 32 ug/L). Although trace amounts of the gasoline additive MTBE (<5 ug/L) were detected in downgradient Wells 085-236 and 085-237. This compound was also detected in a sample from upgradient Well 085-235. (Note: MTBE has been in use as a gasoline additive since 1977.)
• As noted above, concentration levels for petroleum hydrocarbon-related compounds were much lower in samples collected in early June, with total xylene concentrations down to 14 ug/L, ethylbenzene at 0.8 ug/L, 1,2,4-trimethylbenzene at <0.5 ug/L, 1,3,5-Trimethylbenzene at 5.5 ug/L, and naphthalene at 1.4 ug/L. The reduction in concentrations may be due to changes in groundwater flow directions near the Service Station caused by recent increased pumpage from one of the nearby carbon tetrachloride extraction wells (EW-14).
• Tetrachloroethylene (up to 37 ug/L) was also detected in a number of Service Station area wells, and is probably related to historical degreasing operations.
• In April, BNL installed two additional wells (085-238 and 095-183) approximately 200 feet downgradient of the Service Station primarily to better characterize the extent of carbon tetrachloride contamination. Results from the initial sampling of these wells in early June indicated carbon tetrachloride up to 2,080 ug/L and tetrachloroethylene 12.6 ug/L in Well 095-183. The lack of petroleum hydrocarbon compounds at this distance away from the Service Station is consistent with numerous studies on petroleum hydrocarbon spills, where it has been found that compounds such as xylenes, ethylbenzene, 1,2,4-trimethylbenzene, and naphthalene degrade rapidly and, therefore, do not migrate great distances from source areas.
• No floating petroleum has been detected in the Service Station facility wells.

• Carbon tetrachloride detected in both upgradient and downgradient wells originates from the former storage tank area located approximately 200 feet to the west (upgradient) of the Service Station. However, chemicals associated with petroleum hydrocarbon (oil/gasoline) products are found only in wells located downgradient of the Service Station, indicating that these originate from releases at the Service Station.
• The source of the petroleum hydrocarbon contamination is believed to be historical because: 1) there has been no indication of leakage from the tanks based upon electronic leak detection system monitoring and daily product reconciliation (i.e., an accounting of the volume of gasoline stored in underground storage tanks and volume of gasoline sold); 2) all waste oils and used solvents generated from current operations are being properly stored and disposed of; and 3) if these contaminants were related to a recent (significant) gasoline spill, it would be expected that the contaminant mixture would include high levels of benzene, toluene and the gasoline additive MTBE.
• Although the Service Station did have a number of floor drains, they drained to an oil/water separator prior to discharge to the BNL Sanitary System. The floor drains were sealed in 1990.

• Regulators (EPA, NYSDEC, and SCDHS) have been notified of groundwater monitoring results.

• An investigative team has been formed to identify the source of contamination and develop necessary corrective actions.
• Review of historical product reconciliation records, spill records and chemical inventories for the Service Station are being reviewed.
• The status of the oil/water separator associated with the former floor drain system is being evaluated.

• The source of carbon tetrachloride was previously identified, and a treatment system is already operating to remove the VOCs. The Environmental Restoration program is currently evaluating the full extent of carbon tetrachloride plume migration and the possible need to expand the groundwater treatment system. Groundwater samples from these wells are being collected on a monthly schedule as part of the Carbon Tetrachloride Plume Removal Project.

• Groundwater modeling and routine evaluation of groundwater flow conditions is being conducted as part of the Carbon Tetrachloride Plume Removal Project to verify that the placement and depth of wells are appropriate.
• Evaluation of any other required actions continues.

• BNL is taking actions to identify the source, and will remediate residual contamination as appropriate. Based upon the types and concentrations of VOCs detected, it is likely that the contamination is from historical surface spillage, and not from current Service Station operations.
• Because the closest BNL drinking water supply well is located several thousand feet northwest (upgradient) of these source areas, this contamination will not impact BNL’s potable water supply.
• The enhanced groundwater monitoring network as designed enabled us to identify this contamination. This detection resulted from BNL’s systematic and comprehensive approach to evaluating its facilities. The Laboratory is implementing this part of the Environmental Management System to collect information on groundwater quality. BNL will use the information to determine what additional actions are needed, and to continue to improve our groundwater protection program. Although groundwater monitoring is an important means of evaluating a facility’s impact on the environment, BNL’s primary focus is to aggressively control or eliminate pollution at the source to protect the quality of the groundwater resource.