Remediation of soiled masonry in historic structures contaminated by the Gulf Coast oil spill of 2010
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The objective of this thesis was to understand the factors that affect the selection of remedial treatments for the complex staining of masonry materials on cultural resources located in environmentally sensitive sites such as Fort Livingston, Louisiana, on the Gulf Coast of the United States and other locations impacted by pollutants including crude oil. After the Deepwater Horizon oil spill in April 2010, the brick-and-tabby Fort was stained by crude oil. The EPA recommends SWA for removal of oil from solid surfaces such as masonry; however, limited research has been conducted into SWA effective for removal of crude oil from masonry, particularly in remote and environmentally sensitive locations. Research was conducted collaboratively at NCPTT and UT-Austin to identify a series of suitable SWA and to develop methods for evaluating SWA effectiveness in the laboratory. Products were selected for laboratory evaluation that do not require long dwell times, are easy to transport to the site, can be applied with portable equipment, produce effluent that can be collected for off-site disposal, and are listed on the EPA-published NCP Product Schedule. Two sets of 36 brick samples each were soiled with crude oil from the Fort. One set of samples was artificially weathered and one set was unweathered prior to being cleaned with selected six SWA. Laboratory evaluation shows that the primary factor affecting cleaner selection for remediation of brick masonry stained by light crude oil is the extent of weathering of oil on the masonry. For light crude oil, such as that spilled in the Gulf, organic solvent-based cleaners may be most effective if cleaning is possible soon after the staining occurs. Aqueous surfactant cleaners are most effective for removing weathered light crude oil from masonry. The following SWA listed in order of performance are recommended for field trials at Fort Livingston: 1. Cytosol; 2. SC-1000; 3. De-Solv-It APC; 4. De-Solv-It Industrial followed by De-Solv-It APC; 5. De-Solv-It Industrial followed by SC-1000.