Landfill Leachate Fate and Transport within Estuarine Flux, and Implications for Air Sparging Remedial Activities, Steamboat Creek, Norfolk, Virginia
The Campostella Landfill is in Norfolk, Virginia along Berkley Avenue and near the Steamboat Creek. It was constructed unlined on a wetland and accepted waste from 1944 to 1992 with no leachate collection system. Groundwater monitoring began in 1994, since 2001 on a semi-annual basis. Groundwater monitoring shows leachate-contaminated groundwater beneath the landfill with primary contaminants being volatile organic compounds (VOCs) of benzene and naphthalene, and metal arsenic. Groundwater equipotential maps show groundwater beneath the landfill flowing into the tributaries of Steamboat Creek that flows into the Elizabeth River. Recent surface water samples from tributaries of Steamboat Creek confirms these links. A Correction Action Program (CAP) is being implemented to treat the VOCs in the groundwater by in-situ air sparging, coupled with monitoring of the metal contaminants. This study was to evaluate the fate and transport of the VOC and metals contaminants in Steamboat Creek and loading to the Elizabeth River and implications of the CAP. Finite-segment method (FSM) and steady-state response matrix (SSRM) were used to conceptualize a model to simulate the contaminant mass transport and decay (via volatilization, oxidation, and/or settling) within the upper (southern) extent of Steamboat Creek, which is a tidal estuarine aquatic environment, water levels ranging from 5.14 feet to -2.76 feet MSL. The upper Steamboat Creek was divided into four equal-volume segments and the salinity gradient in situ was used to estimate the dispersion coefficient. Velocity measurements during peak ebb and flood tides were used to estimate the net discharge from the upper Steamboat Creek. Published decay values of the contaminants by settling and volatilization or oxidation were used to determine the fate of the contaminants in Steamboat Creek. Although recent surface water samples indicate presence of these contaminants in portions of Steamboat Creek adjacent to the landfill, results of the FSM and SSRM indicates contaminant concentrations are reduced below the laboratory analyses’ detection limits within the most-downgradient segment, if not further upstream, even without the use of active remediation to reduce VOC loading to Steamboat Creek. The SSRM was also used to estimate the mass of contaminant loading needed for the downgradient segment to violate the lowest applicable water-quality standards for future assessment and evaluation of monitoring data.Author Bio
Kyle Quick: Graduate student, Environmental Engineering Master Program; Department Civil and Environmental Engineering, Kaufman Hall 135, Old Dominion University, Norfolk, VA 23529; kquic001@odu.edu Kyle Merchant: Graduate student, Environmental Engineering Master Program; Department Civil and Environmental Engineering, Kaufman Hall 135, Old Dominion University, Norfolk, VA 23529; kmerc002@odu.edu Jaewan Yoon: Associate Professor, Department Civil and Environmental Engineering, Kaufman Hall 135, Old Dominion University, Norfolk, VA 23529; jyoon@odu.edu
