Soil and Groundwater Investigation at the Lincoln Memorial

Hartman-Cox Architects AAS Environmental, Inc.

This report examines the soil contamination at the Lincoln Memorial in Washington, D.C. The National Park Service was concerned about possible soil contamination that may have resulted from a 1986 hydraulic fluid leak adjacent to the elevator pit in the statuary chamber undercroft or basement. AAS Environmental, Inc. (AASE) performed the initial soil investigation in December of 1992 to determine if indeed the soil was contaminated and to identify the extent of the contamination. The soil samples were analyzed for Total Petroleum Hydrocarbons (TPH). These test results are included in Appendix B beginning on page 46. Because the levels found were above the District of Columbia Department of Consumer and Regulatory Affairs (DCRA) recommended action level of 100 parts per million (ppm), a second series of soil samples were tested to determine the limits of the contamination. Again the TPH levels were significantly above the action level. In September of 1993, AASE undertook a comprehensive sampling study to define the limits of the contamination. Eleven areas scattered throughout the undercroft of the memorial were found to be above the DCRA action level. A graphic representation of these results can be found on page 37. With this information in hand, the National Park Service notified DCRA of the contamination. DCRA requested soil and groundwater analyses around the outside of the memorial to determine if all soil on the grounds are contaminated and if groundwater is potentially transporting the contamination away from the memorial. AAS Environmental, Inc. (AASE) conducted soil and groundwater testing at the Lincoln Memorial in Washington, D.C., from June 7 to June 13,1994. The soil samples were analyzed for TPH. No hydrocarbons were found in any of the 43 soil samples. After the wells had been fully developed (by pumping fix>m the wells an amount of water equal to ten times their volume), a water sample was collected from each of five wells and analyzed for TPH. No hydrocarbons were detected in the groundwater. Because of the negative results obtained outside the memorial, it was determined that the extent of the petroleum contamination was limited to the soil in the undercroft. However, previous soil investigations of the undercroft were only conducted by hand auger to a depth of approximately five feet. Therefore soil borings in the undercroft must be performed through the use of a drill rig to determine the depth of the contamination. Once this is known, remediation efforts are requited. Therefore, AASE has recommended four effective remediation alternatives. The first is encapsulation of the soil with concrete. The other three arc in sim remediation methods: soil vapor extraction, thermally enhanced recovery, and bioremediation. All three of these methods are effective from both a cost and time perspective. AASE does not recommend soil removal as an alternative because of the tremendous time and cost involved. It is not possible at this time to select the best remediation method to be used at the memorial because of the number of variables yet to be determined (i.e. soil characteristics, impacts on the foundations, impacts on vegetation, and depth of contamination). In order to properly determine the best remediation method, a complete geotechnical and civil study of the soils, the foundation, and other variables must be performed, and then a remediation design must be drafted. The DCRA must then approve any remediation plan prior to commencement of the work.

Soil and Groundwater Investigation at the Lincoln Memorial

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