Formatted Title
Design and Installation of a Thermally-Enhanced Biological Barrier
Background/Objectives
The site is an active manufacturing facility located in the State of Sao Paulo, Brazil. The site is underlain predominantly by 10 to 25 m thickness of unconsolidated fluvial sediments (mixed clays, silts and sands). Groundwater depth is approximately 5 m below ground level and flows towards an important river at the area. The main objective of this work was to evaluate the potential of thermally-enhanced biodegradation to address dissolved phase COC impact and create a barrier between the existing plume underneath the production area and the environmental protected area and ultimately the river.
Approach/Activities
This assessment initially comprised the creation of a thermal model using Petrasim, the graphical interface for the TOUGH2 family of simulations/codes used to solve problems related to geothermal systems and multi-phase contaminant transport. A TMVOC model (an extension of the TOUGH2 general-purpose simulation program) was used to create the model for this Site. The results of the model suggested the concept was feasible and heating to a temperature of 35 to 450 degrees Celsius could be achieved within 2 weeks. However, to confirm applicability at the Site, a field-scale pilot study was implemented via localized steam injection, with the aim to create a heat-enhanced biological zone. Steam was continuously injected into pilot test wells for a time period of approximately 2 months, and several wells monitored the temperatures. Groundwater samples were collected to provide baseline microbial population prior to heating and then at 30 and 60 days after heating commenced.
Results/Lessons Learned
Biological sampling conducted after heating showed a significant increase in microbial populations, including microorganisms known to degrade the key contaminants. The trial has shown applicability of the approach tested to achieve the project objectives. The data collected were used to finalize the full-scale design and confirm well location, steam flow rates and target treatment temperature to achieve optimum efficiency and technical performance. Full-scale field work implementation is scheduled to end in December 2023.