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Naval Surface Warfare Center - Dahlgren

Current Site Information

EPA Region 3 (Mid-Atlantic)

Virginia
King George County
Dahlgren

EPA ID# VA7170024684

1st Congressional District

Last Update: February 2014

Other Names

None

Current Site Status

The Naval Surface Warfare Center-Dahlgren (NSWC) has taken action at 20 of the contaminated sites at the facility. Below is a discussion of several recent activities.

Remedial work is underway at two Operable Units on NSWC Dahlgren. During the excavation of the former burn pit at OU 01 (Site 12), which started in December 2008, several canisters/bottles were discovered. Material in these containers could not be identified, the excavation site was closed, and a Chemical Safety Submission (CSS) was prepared and approved by the Army. Removal work restarted in February 2012 and the field activities were completed in June 2012. Metals and volatile compounds are the contaminants of concern at OU 01 and have continued to leach to the groundwater at an unacceptable rate. Remedial action field work at OU 01 was completed in August 2013. At OU 19 (Site 20/23), remedial work started in March 2008 and was completed in March 2010. The media of concern includes both soil and groundwater and the contaminants are mainly volatile organics. Soils and an underground tank were excavated in early March, 2008 and Phase II of the remedy (groundwater injections) started Spring 2010. Additional groundwater injections are planned for 2014.

Remedial work will start for OU 17 (Site 61a) in the Summer of 2016. Pre-design (a pilot test) work started in March of 2012. At OU 17, soils are contaminated with metals and explosive residue and the potential for explosive ordnance. The ROD for OU 17 is planned for September 2015 and remedial work should be completed at OU 17 in September 2018.

Removal actions were completed at OU 26 (Sites 4 & 15). Contaminants at OU 26 included metals in the soils and the potential for explosive ordnance. The removal action at OU 26 had restarted in April 2009 after more than 24 months to approve an Explosive Safety Submission (ESS), a Site Analysis Request (an Explosive Location Plan), and the approval of a new blast shield design to be used during excavation. Removal field work was completed in the late fall of 2011. The final Verification Sampling and Analysis Report, that documents that the removal reached the clean-up goals is currently under review.

An initial soil removal action was completed at OU 24 (Site 14), where chromium contaminated soils leached to the groundwater. A munitions team from APG tested sediments in the piping in August 2007 and tested the iron piping and underlying soils in December 2007 for the potential for chemical warfare residue (no detections). Field work finished at OU 24 in June 2009 and a Record of Decision for OU 24 will be signed by March 2015.

A draft Engineering Evaluation/Cost Analysis (EE/CA) was prepared for OU-27 (Site 57) in October 2009, with removal of soil and debris planned by June 2010. The EE/CA was withdrawn by the Navy and additional sampling indicated that there was not an unacceptable risk related to the soils at OU-27. A final EE/CA for OU-28 (Site 63) was prepared in December 2009, the removal action started in March 2011 and was completed in June 2011.

Additional investigations at the facility are underway.

Site Description

NSWC-Dahlgren is approximately 4,300 acres and located 40 miles south of Washington, D.C. along the Potomac River. This naval facility, established in 1918, conducts research, development, testing, and evaluation of surface ship weaponry. Activities at Main Side, a 2,678-acre area include air operations, ordnance testing, laboratory testing, computer facilities, administrative offices, and residences. The Explosive Experimental Area (EEA), is an isolated testing range located on 1,614 acres. Both areas are separated by the Upper Machodoc Creek. Two aquifers underlying NSWC-Dahlgren provide non-contaminated drinking water to the nearby population: the shallow Nanjemoy aquifer, supplies a small number of private residences, and the deeper Potomac Group aquifer supplies the municipal and NSWC-Dahlgren water systems. Wetlands along Gambo Creek, an unidentified drainage area, and the Potomac River are environmental concerns. Municipal and private wells located within 4 miles of the site supply water to an estimated 6,900 people.

The Navy has identified several sources of contamination at NSWC-Dahlgren. The Fenced Ordnance Burial Area (Site 2), was used for burial for excess munitions and has metals detected in the surface soils, in addition to several nearby trenches filled with wastes. The Terminal Range Airplane Park (Site 6), was an area used to store target materials is contaminated with heavy metals and polyaromatic hydrocarbons (PAHs) The Disposal/Burn Area (Site 9), a 2 to 3 acre landfill is contaminated with PAHs and the soils and sediment contain phenols, metals, pesticides waste. Site 9 is a threat to the groundwater as well as to the wetlands that surround the landfill. Hideaway Pond (Site 10) contains sediment and fish which are contaminated with mercury. The Chemical Burn Area (Site 12), was used for decontamination of testing materials and has 1,1,1 trichloroethane (TCA) in the alluvial aquifer below the site. The Chemical Waste Evaporation Pond (Site 14) was used for the disposal of decontaminated chemicals from 1967 until the late 1970s. The 1400 Area Landfill (Site 17), 5 to 10 acres in size, received municipal waste for three years in the 1970s and canisters of mercury may have been disposed of in this area. Low levels of mercury were detected in groundwater underlying Site 17 and in stream sediments nearby. The Transformer Draining Area (Site 19), where electrical transformer oil containing polychlorinated biphenyls (PCBs) was drained has PCB contamination to a depth of 4 feet. The Former Electroplating Waste Underground Storage Tank (Site 20) has minor solvent contamination in the groundwater. The Pesticide Rinse Area (Site 25), where pesticide containers were rinsed is contaminated with pesticides. The Lead Contamination Area (Site 37) contains used sand from firing ranges with residual heavy metals as contaminants. Landfill A: Stump Dump Road (Site 46) used in the 1940's and 1950's for general disposal has PAH, PCB, and heavy metal contamination. The Fill Areas Northeast EEA (Site 50) is a small burial dump that has PAH and heavy metal contamination. The Gambo Creek Ash Dump (Site 61a) where residual ash was deposited, may contain heavy metals, especially mercury and is in contact with sediments in Gambo Creek. There are also six sites that are related to the former use of munitions, including depleted uranium, and explosives.

Site Responsibility

Cleanup of this site is the responsibility of the Federal government.

NPL Listing History

This site was proposed to the National Priorities List on February 7, 1992. The site was formally added to the list October 14, 1992, making it eligible for federal cleanup funds.

Threats and Contaminants

Elevated levels of various Volatile Organic Compounds (VOCs), semi-Volatile Organic Compounds (SVOCs), metals, PCBs, radioactive impacted areas, and explosives have been detected at the facility, affecting soils, sediments and groundwater.

The response actions (discussed below) undertaken by the Navy have greatly reduced the potential threats and risk from several sites.

Contaminant descriptions and associated risk factors are available at the Agency for Toxic Substances and Disease Registry’s (ATSDR’s) Web site.

Cleanup Progress

The Navy removed soil from a small PCB-contaminated area at Site 19 and metals contaminated soil at Site 39 and Site 3 and 44. Additionally, a small area contaminated with radioactive material has been removed. The Navy also removed two other small piles of soil that contain depleted uranium in 1999 and closure of these sites was completed in 2001.

A RCRA Subtitle C landfill cap was installed at the Fenced Ordnance Burial Area (Site 2) in the summer of 1998 and at the same time the Air Sparging and Soil Vapor Extraction System was installed at the Chemical Burn Area (Site 12). A removal action was performed to close the Rocket Motor Pit/Ordnance Burn Structure (Sites 3 and 44) in late 1998. The Disposal/Burn Area (Site 9) and the 1400 Area Landfill (Site 17) had RODs signed in September 1998 and the cap for Site 9 was completed in October 1999. Construction of the cap at Site 17 was completed in the late fall of 2000. The Pesticide Rinse Area (Site 25), and the Transformer Draining Area/Battery Service Area (Sites 19 and 29) had RODs signed in September 1999. Construction at Pesticide Rinse Area (Site 25) started in May 2001 and was complete by October 2001. Hideaway Pond (Site 10), had a ROD signed in September 2000. A removal action was completed at Fill Area Northeast EEA (Site 50) in October 2001. A ROD for removal of soil and sediment at the former dump (Site 46) was signed in September 2001 and remedial action was completed in October 2003. A ROD for removal of soil and sediment at the storage area (Site 6) was signed in September 2002 and remedial action was completed in June 2004. The remedial design for the excavation of soils at Site 37 was completed in March 2005, however, because of the discovery of explosives at depth, a new remedy (a soil cover) had to be re-proposed and a new ROD was signed in August 2006. The remedy at Site 37 started in September 2006 and the majority of the construction was completed in November 2007. Additional wetlands were planted at Site 37 in the fall of 2008. The remedial action was completed in April 2009. A NFA ROD was signed for Site 62 in September 2005 after the removal of a former french drain. The Navy started a removal action at two storage areas (Sites 4 and 15) in late summer 2005 and planned to complete the removal in late 2007. However, the removal action was stopped in May 2007 because of the discovery of explosives and a new policy on handling explosives. Work resumed in April 2009. Removal field work was completed in the late fall of 2011.

The Navy completed a removal action at a buried munitions mound (Site 47a) in October 2005. An Action Memo was signed in December 2006, after an Engineering Evaluation/Cost Analysis (EE/CA) was prepared for removal of a former chemical waste decontamination pond (Site 14). The removal action at Site 14 started in January 2008, was completed in June 2009 and a Record of Decision will be signed in 2012. A ROD Explanation of Significant Differences (ESD), requiring the removal of a former pit at Site 12, was signed in January 2007 and a ROD requiring removal of a source area and treatment of groundwater contamination at Sites 20/23 was signed in September 2007. The Work Plan for the removal at Site 12 was approved in December 2008 and the work started that same month. However, work has been stopped until a new sampling and analysis plan can be developed. Remedial action at Site 12 was completed in June 2012. The source removal at Sites 20/23 was completed in February 2008 and groundwater injection work started in the spring of 2009. A final EE/CA for OU-28 (Site 63) was prepared in December 2009 and the removal action was completed in June 2011.

Continuing investigations are underway at lower priority (lower risk) areas across NSWC-Dahlgren.

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