The Site-Wide Work Plan Spring Valley FUDS provides the details of the procedures, methods, organization, and resources being used to achieve project objectives. The mission of the Corps in Spring Valley is to identify, investigate, and mitigate threats to human health and safety or to the environment resulting from past DOD activities in the area.
2.2.1. DATA QUALITY OBJECTIVES FOR SITE INVESTIGATIONS
Environmental investigations at the Spring Valley FUDS are conducted to ensure that the data collected are of the right type, quality, and quantity to support defensible site decisions. The data quality objectives for this project were developed using this guidance: “Data Quality Objectives Process for Hazardous Waste Site Investigations.”136
The CSM for the Spring Valley FUDS was initially developed by the Corps. In general terms, the CSM focuses on encountering chemical agent or arsenic (a Lewisite degradation product), and other contaminants that may have resulted from AUES operations. Potential receptors include private residents, students, construction workers, and groundskeepers. Potential exposure scenarios (regarding surface and subsurface soil, and bottle contents) include dermal contact, and direct ingestion and inhalation of fugitive vapors and particulates.
2.2.2. INITIAL INVESTIGATION RESULTS (1993-1995)
Of the more than 1,900 anomalies identified, a total of 840 anomalies were recommended for further study or removal. Nearly all of the anomalies were determined to be metallic debris from property development, but one piece of ordnance, a spent Livens smoke round, was found. Two other ordnance rounds were anonymously left at the investigation office trailer. An additional 3-inch Stokes mortar round was discovered during the digging of a basement. This round was unarmed. Approximately 20 other pieces of ordnance scrap items were also found. All of these items were safely removed from the site. No additional burial pits were identified, and no additional chemical warfare materiel was found. In addition to the geophysical investigations, a total of 260 soil samples were collected at 13 areas that included 17 POIs. Samples were taken from randomly selected locations, within each POI, as close as possible to the 1918 surface level. The samples were tested and analyzed by both the Corps and the EPA.
Analytical sampling results were compared to:
- EPA Region III Risk-Based Concentrations (RBCs) for residential exposures.
- Health-Based Environmental Screening Levels (HBESLs) (risk-based screening levels of chemical warfare agents) for residential exposures derived by the DOD.
- Site-specific background concentrations for inorganic chemicals.
Region III RBCs and the HBESLs were developed using chronic estimates of exposure of the general public and chronic toxicity values. Commonly, these risk-based screening levels are calculated for a 1x10- 6 cancer risk or a hazard index of 1 for non-carcinogens. However, both the RBCs and HBESLs for non- carcinogens were adjusted downward by a factor of 10 to account for potential cumulative effects. Such screening-level assessments are often used to identify areas for further investigation and possible remediation. Generally, where analytical sampling results fall below screening levels, no further investigation or action is warranted under Superfund.
Although no chemical agents, chemical warfare agent-unique breakdown products, explosives or explosive breakdown products were found in any of the samples taken, several metals were identified that exceeded the EPA's RBCs. These metals were included in a quantitative baseline risk assessment. This assessment found no elevated health risk requiring remedial action. Arsenic was not identified as a chemical of potential concern for remedial action as the sampling results from these early investigations were not significantly different from site background concentrations.
These findings were documented in a Remedial Investigation Report dated June 1995. This report was followed by a No Further Action Record of Decision in June 1995. In this decision, the Army took responsibility for any future actions required if additional munitions or contamination related to past military activities were discovered.
2.2.3. FOLLOW-UP INVESTIGATIONS
In 1996, the D.C. Health Department reported to EPA that they had uncovered new information regarding the Spring Valley site. The Corps responded to each of the issues raised by the D.C. Health Department. As one of the issues addressed, the Corps conducted field investigations of the area located along Glenbrook Road. More than 600 items were recovered including 288 ordnance-related items. Of those items, 14 were evaluated to have chemical warfare agent, predominantly HD. Following this work, soil samples were collected from the recovery site. Test results indicated elevated levels of arsenic were present in portions of the area. Following a comprehensive risk assessment, the Corps determined that the top two feet of soil in the affected areas should be removed and replaced with new soil. This work began in December 2000 and was completed a few months later.