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Simulation of 100-yr Flood Induced Soil and Sediment Contaminant Transport @ a RCRA Facility in NJ
Citation:
Shabani, A., P. Whung, D. Cutt, M. Mehaffey, R. Vargas, S. Woznicki, AND M. Ramirez. Simulation of 100-yr Flood Induced Soil and Sediment Contaminant Transport @ a RCRA Facility in NJ. NJDEP Seminar, webinar, June 30, 2020.
Impact/Purpose:
The slides will be shared with NJDEP management of individuals who are aware of the project, and will not be shared nor cited further. The goal of sharing would be to provide them with an update and also to help internal NJDEP conversations as we plan to reform land use rules to address flooding and other impacts from climate change. In line with this, DEP is working on a Climate Resilience Strategy that plans to incorporate this issue of flooding at SRP sites.
Description:
Due to the massive energy of flood water and its potential to expand a river floodplain, significant concerns exist regarding possible mobilization and transport of contaminants to adjacent communities from hazardous waste sites located in the floodplain. Working closely with our State and Regional partners, we developed a coupled hydrodynamic (HEC-RAS 2D) and water quality (Water Quality Analysis Simulation Program, WASP) model approach to address the research gaps and to deliver spatiotemporal distribution of chemical pollutants with 100- and 500-year return periods for contaminated sites. Our presentation focuses on calibrated results from HEC-RAS model for the Chevron Refinery facility in Perth Amboy, New Jersey (approximately 5.8 km2). Flood discharges were calculated for two main streams (i.e., Woodbridge Creek and Spa Spring Creek) in the study area using the HEC-HMS model and used as inputs to HEC-RAS. The HEC-RAS model was configured with nominal computational grid size of ≤30 m and included hydraulic structures such as bridges and berms around storage tanks. Results of the 100- and 500- year calibrated floodplain extents agree with their corresponding U.S Federal Emergency Management Agency's (FEMA) floodplains and identify inundated areas for the Chevron Refinery facility and its nearby communities. The maximum absolute water surface elevation uncertainty is 0.09 m across the area. Following HEC-RAS calibration, we developed a hydrodynamic linkage to extract HEC-RAS flow velocity, water surface elevation and water depth to be used as inputs to WASP. We used multi-year in-situ soil sampling data and compared multiple geostatistical methods (kriging, inverse distance weighting, and splines) to estimate geospatial concentrations of contaminants of interests (e.g., lead, benzopyrene, arsenic, etc.) in soil across the study area. The data was used in the WASP model for initiation, calibration, validation and uncertainty analysis. The WASP model estimates of sediment erosion, transport, transformation, and deposition of contaminants of interest during the flood events and produces maps of spatiotemporal distribution of contaminants.