Horizontal and Vertical Work Well Together: A Combined Vertical and Horizontal Dual Phase Vapor Extraction System
by Glenn Nicholas Iosue, P.E.
A client was challenged with both chlorinated solvents and fuel oil underneath a commercial property. This commingled plume further complicated matters with vapor intrusion into an occupied building.
Vertical extraction was limited due to low ceiling clearances and restricted access within the building. To overcome these challenges, horizontal remediation technology was used to target the source area.
A combined vertical and Horizontal Dual Phase Vapor Extraction system was selected to remediate the chlorinated solvents from the former dry cleaner facility and fuel oil from leaking underground storage tanks (LUSTs).
The Combined Vertical and Horizontal Dual Phase Vapor Extraction system included:
- One (1) four-inch horizontal extraction well strategically and precisely located underneath the building slab and where access was limited, and,
- Two (2) four-inch vertical extraction wells where access did not pose an issue.
Layout showing the combined
Vertical and Horizontal Dual Phase Vapor Extraction System
The remedial objective was to reduce soil vapor and groundwater concentrations below regulatory levels to address Imminent Hazard (IH) conditions within the building.
The flow rate of the extraction system was designed to simultaneously operate all three extraction wells. Within a month, there was significant reduction of dissolved phase chlorinated volatile organic compounds (CVOCs) and polycyclic aromatic hydrocarbons (PAHs). After 7 months, no CVOCs or PAHs detected during the sampling. The combined vertical and Horizontal Duel Phase Vapor Extraction system successfully mitigated the subsurface impacts.