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Lisa Reyenga
Lisa Reyenga

Senior Engineer
GEI Consultants, Inc

Lisa is a Senior Engineer, with GEI Consultants, specializing in NAPL multiphase characterization and risk-based remediation. Provides strategic planning and regulatory support and advocacy for sites across the country to ensure remedial activities are advancing the site towards reduced risk and site closure. She earned in BS from Tufts University and MS from the Massachusetts Institute of Technology. Lisa is the editor of the ejournal Applied NAPL Science Review.


POSTER PRESENTATION

The default responses to address NAPL impacts in sediment have been to physically remove them or immobilize them. It has been assumed that the presence of NAPL alone requires a response, without an evaluation of the potential for a completed exposure route to impact human health or the environment. Following the framework currently under development by ASTM, the potential for NAPL movement via advective movement or ebullition facilitated BAPL flux can be evaluated. Two case studies will be presented. Site A is a former manufactured gas plant on a barrier island. Site B is a former refinery adjacent to a major US river. The site includes lagoons that were formerly used for wastewater discharge. The investigation approach and results will be presented for each site along with a discussion of how the results are being utilized to inform the ongoing remedy evaluation.

Ebullition is ubiquitous in sediment environments. Where ebullition occurs in the presence of NAPL contaminated sediment, it can provide a transport mechanism for NAPL to enter the surface water body and be observed as sheens on the water surface. This study monitored the occurrence of ebullition-facilitated NAPL flux in lagoons that were formerly used as settling ponds for refinery wastewater discharge. Based on a qualitative survey, an area with high potential for ebullition-facilitated NAPL flux was identified for ongoing evaluation by observations from an unmanned aerial vehicle (UAV). The videos were visually processed to identify the number of bubbles observed and estimate an ebullition rate across the entire monitoring area. The occurrence and area of sheens was estimated for a subset of the monitoring events and single area. The case study outlines how UAV surveys can be a useful tool for estimating ebullition-facilitated NAPL flux over a large area.


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