FRC 2025 Poster Presentations

SAMPLE Poster

Alternative Solutions for Contaminant Remediation: An Evaluation of Two Horizontal Case Studies

Elliott Andelman, P.G., Environmental Project Manager, Directional Technologies, Inc.

Abstract:

Background/Objectives:    

Two case studies are presented where horizontal remediation wells (HRWs) were selected as the remedial solution to target subsurface contamination as an alternative to traditional vertical methods at sites in Florida.    Challenges presented in Case Study 1 involved access restrictions to groundwater contamination that resided beneath above ground storage tanks (ASTs), limited staging and setup locations for the drill rig, and 24/7 facility operations that could not be impeded during well installations. Vertical drilling techniques were not a feasible solution due to the surface-level access restrictions on site.     Challenges presented in Case Study 2 involved targeting subsurface contamination beneath a busy intersection and off-site adjacent properties with limited surficial access availability. Shutting down the gas station for the installation duration would significantly impact business revenue and was therefore not an option.  

Approach/Activities:

Twenty one (21) individual horizontal air sparge (HAS) wells were installed from four (4) discreet rig staging locations, which were strategically selected to avoid significant restoration costs and prevent disruptions to 24/7 on-site activities. Advanced drill-bit locating services were implemented to accurately install the wells beneath the ASTs and active roadways where standard walk-over locating services were not feasible. Wells were installed via the blind installation method, where an exit point is not required, due to site space constraints.     Eight (8) horizontal wells were installed to combat a petroleum release at a gas station bordered by a busy intersection and neighboring commercial and residential properties. Contamination had migrated slightly upgradient beneath the intersection and downgradient off-site onto adjacent properties. Vertical drill rigs could not be positioned above the upgradient contamination without shutting down the intersection. Down-gradient access had not been granted by the property owners to install vertical remediation wells. All 8 wells were installed via the entry-exit method, contrary to the installation method used in Case Study 1.     

Results/Lessons Learned: 

Horizontal remediation wells were able to access the target contaminated zones and perform the necessary remedial applications at the sites in both Case Study 1 and Case Study 2, despite the site-specific challenges presented at each site. By utilizing horizontal directional drilling techniques, there were no disruptions to business operations and no loss to client revenue as a result of installation operations. Through teamwork and collaboration with the environmental consultants, the horizontal well screen designs were optimized for each remedial application. Installation techniques were chosen based on site access restraints to install the wells into the target locations and ultimately reduce the remedial timeline of each project.   

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