of the intake for the District of Columbia water system at Little Falls Dam. Water is supplied to residents in the OSR FUDS area through the District of Columbia water supply.

2.1.4

Groundwater flow in the piedmont rocks and saprolite of the OSR FUDS is anticipated to follow the topographic gradient toward the southwest and the Potomac River. Groundwater is not used for public water supply at the OSR FUDS. No private, domestic, or commercial wells have been observed at the site during field activities.

2.1.5 A Record of Environmental Consideration for Remedial Investigations at Spring Valley was completed on January 27, 1993.

2.2.1 The American University Experiment Station (AUES) was used by the U.S. Army and Navy during World War I to investigate the production of noxious gases, antidotes, and protective masks. Initially operated by the Bureau of Mines, the AUES was transferred to the U.S. Army and was operated by the U.S. Army until 1918, when the experiment station was closed. The land around the former AUES was subsequently developed into an urban residential neighborhood located in Northwest Washington, D.C. In January 1993, a contractor digging a utility trench uncovered buried ordnance. The U.S. Army responded with Operation Safe Removal.

2.2.2 Operation Safe Removal consisted of two phases. Phase I was the immediate emergency response after the discovery of buried ordnance in January 1993. Phase I of Operation Safe Removal began on January 5, 1993 and ended on February 2, 1993. The ordnance items included 141 intact munitions, assorted ordnance-related debris, and laboratory material. The buried ordnance items were removed by the U.S. Army. Forty-three of the

intact munitions recovered were deemed suspect chemical munitions and subjected to further on-site qualitative analysis. This analysis confirmed that the items were chemical munitions.

Nine

of the suspect chemical ordnance items were subjected to quantitative off-site analyses. The results of these analyses revealed that one munition contained mustard agent, five contained aqueous salt solutions, two contained fuming sulfuric acid, and one contained gun cotton. Soil, surface water, and groundwater samples were collected during the removal of the ordnance items. The analysis of the soil samples collected from the excavated area and soil, surface water, and groundwater samples collected from the vicinity of the excavated area indicated that no residual contamination was present as a result of buried munitions.

2.2.3 On January 21, 1993, the Findings and Determination of Eligibility was approved establishing the OSR FUDS. This study determined that 509 acres were eligible, with an additional 107 acres subsequently added as an addendum, as part of the OSR FUDS. An inventory project report conducted by the U.S. Army concluded that Chemical Warfare Material (CWM) hazards could potentially be present at the site. Consequently, the Army determined that it was necessary to conduct a remedial investigation (RI) to determine if Ordnance and Explosive Waste (OEW) or CWM were actually present at the site and posed potential adverse health risks. The RI was performed during Phase II of Operation Safe Removal.

2.2.4 Phase II of the RI began immediately after Phase I on 3 February 1993. Phase II included the historical records search, geophysical survey, intrusive studies, non-time critical and time critical removal actions, environmental sampling, and risk assessment necessary to determine the existence and extent of any OEW and/or OEW- or CWM-related environmental contamination within the OSR FUDS as a result of Department of Defense (DoD) activities during World War I. These activities and findings, excluding the

6

Captain Rankin Area, which is still under investigation, summarized in the RI Report.

2.3 Highlights of Community Participation

are

2.3.1 The RI Report was released to the public on 21 March 1995. This document was made available to the public in both the administrative record and in information repositories maintained at the following locations:

The notice of the availability of this document was published in the Washington Post and Washington Times on 21 March 1995.

2.3.2 To provide the community with reasonable opportunity to submit written and oral comments on the results of the RI for the OSR FUDS, the Army established a public comment period from 21 March 1995 through 30 April 1995. A public meeting was held on 23 March 1995 to present the results of the RI and to answer questions and receive comments. A response to the comments received during this period is included in the Responsiveness Summary, which is part of this Record of Decision (ROD). This decision document presents the determination that no further remedial action is necessary for the OSR FUDS in Washington, D.C., is consistent with CERCLA, as amended by SARA and, to the extent practicable, the National Contingency Plan. The decision for this site is based on the administrative record.

2.4 Scope and Role of OSR FUDS Response Action

2.4.1 The RI of the OSR FUDS investigated the site for the presence of OEW and CWM at the site. This ROD is the final action for addressing the potential presence of OEW and CWM at the OSR FUDS, excluding the Captain Rankin Area. The U.S. Army has concluded that there are no OEW or CWM hazards remaining at the OSR FUDS that warrant further remedial action. Therefore, no further action is required for the OSR FUDS. This ROD serves to document this no further action decision.

2.5.1 The RI of the OSR FUDS focused on areas most likely to contain OEW or to be contaminated by OEW, CWM, or their breakdown products. The RI was aided by the historical record of World War I chemical agent research, development, and testing activities of AUES, including a 1918 aerial photograph of AUES. Geophysical surveys of areas of interest four times greater than the size of points of interest (POIs) along with 10 percent of the remaining area, and follow up intrusive investigations of suspect anomalies, were conducted to find any buried ordnance remaining at the OSR FUDS from the activities at AUES. The soil investigation focused on sampling for chemical agents, associated breakdown products, and OEW residue results most likely to be present at points of interest throughout the OSR FUDS. The following subsections summarize the findings of the RI Report.

2.5.1 Ordnance

2.5.1.1 Since the initial discovery of 141 buried munitions, three intact munitions have been recovered at the OSR FUDS. One was a 75 millimeter (mm) shell found in October 1993 near the original AUES area on the surface. This round was assessed as a suspect chemical round. The second was a Livens projectile partially filled with smoke agent which was excavated under a Time