Army Landfill Remediation: Swannanoa, NC
Piedmont Geologic was retained by the North Carolina Department of Administration to assess and remediate an abandoned World War II era landfill, plus resulting soil and groundwater contamination, at the location of the former U.S. Army Moore General Hospital in Swannanoa, North Carolina, a hospital and medical training facility that operated from 1942 to 1959. The five-acre site was subsequently used as an illegal dumping ground for various local residents, business, and industry through the early 2000s.
Concerns and rumors had swirled through the local community for decades regarding the potential contents of the abandoned landfill and its potential health and physical hazards confronting the local community, including, as was claimed, potential unexploded ordinance and lethal gases. The site was the subject of numerous media stories and was placed in a high priority ranking in the NCDEQ inactive hazardous sites database. Security measures put in place to eliminate unpermitted entry by local residents were routinely breached, including by students at a directly adjacent public high school. Neighborhood tensions were high, and the State needed to act with the best professional response they could muster.
The Challenge:
Because no records of the landfill operating practices remained in State records, determination of the landfill contents became an exercise in forensic analysis and detective work. Through compilation of historical news stories and photographs, concerns regarding the potential for unexploded ordinance and lethal gases being present were promptly dismissed. A real concern was instead discovered posed by abundant asbestos-containing materials, in the form of building materials, spread throughout the upper layer of the landfill. As the site was adjacent to a public high school, and was located within the boundaries of a 4H camp (which now is operated by the Black Mountain Home for Children) and educational center, good public relations were paramount to ensuring that all site work was conducted in a manner deemed trustworthy and safe by the community.
The Means:
Site assessment and remediation efforts were completed under jurisdiction of the NCDEQ Inactive Hazardous Sites Branch in accordance with the Registered Environmental Consultant (REC) Program, with Piedmont Geologic acting in the role as REC.
Determination of the landfill contents, areal distribution, and vertical extent was achieved through a multi-disciplinary approach including geophysical techniques, subsurface gas testing, soil borings, and exploratory excavations. Samples of the landfill contents, plus underlying and surrounding soil, were collected and analyzed to evaluate the Hazardous versus Non-Hazardous characteristics of the landfill materials plus the presence of residual contamination in underlying/surrounding soil. Groundwater monitoring wells were installed within and around the landfill to characterize groundwater quality. Risk assessment was completed to delineate soil requiring remediation.
Using field data and computer modeling, the three-dimensional configuration of the landfill was identified and determined to be the result of the gradual filling of a mountain ravine over the nearly two-decade landfill operating period. Landfill mass was estimated through the various models. The landfill was concluded to contain ash from a former hospital incinerator/crematorium that operated in proximity to the landfill, occupying its lower portions, overlain by hospital wastes, including an abundance of medical-related glassware, which, in turn, was overlain by demolition materials from the decommissioning of hospital facilities in the late 1950s, which resulted in a topographic plateau where the ravine had previously existed.
A thorough evaluation of potentially applicable remediation technologies concluded that landfill excavation and removal to an offsite permitted Subtitle D landfill was the most cost-effective and permanent solution for the site, which would result in restoration of the original site landscape. An elaborate stormwater diversion and retention system was designed and constructed to protect local creeks/streams from contaminated stormwater runoff during the remediation effort. An exposure and health monitoring network, including airborne asbestos monitoring, was developed and manned over the course of the project to document that worker and surrounding resident health concerns were protected.
The Result:
A total of nearly 11,000 tons of landfill materials and overlying/surrounding rubbish and debris was removed from the site. The former incinerator/crematorium was razed and disposed. The actual weight of disposed materials removed was within 2% of the estimated weight derived by Piedmont Geologic, which means the project remained within the original State-approved budget. Site regulatory closure was granted by NCDEQ. The site was returned to its original landscape and may eventually be used for livestock grazing by the Black Mountain Home.
