Multi-Phase Extraction
If there is one remediation method that requires maximum removal of contaminated material, it is multi-phase extraction. Horizontal wells can place hundreds of linear feet of screen per well in direct contact with subsurface contamination, removing large volumes of groundwater, vapor, and free product for remedial treatment.
The goal of multi-phase extraction remediation systems is to remove various combinations of contaminated groundwater, vapors, and free products from the subsurface. This is accomplished by using a vacuum system, which can also be combined with a downhole pump, installed inside of a well to extract as much contamination as possible from the subsurface. Due to their increased screen footage compared to vertical wells, horizontal remediation wells offer the ability to remove significantly more contaminant mass from a wide variety of sites. Horizontal remediation wells are often favored for multi-phase extraction contaminant remediation projects because they provide increased exposure to multiple subsurface zones. Horizontal wells can intersect multiple layers of soil and groundwater, allowing for the extraction of contaminants present at different depths and locations within the subsurface. One horizontal well can contain hundreds of feet of screen or more to intercept multiple phases of contamination across large lateral distances.
The “smear zone,” or the zone where groundwater fluctuations occur, is often targeted in multi-phase extraction projects since the free product is “smeared” in this area as groundwater levels rise and fall.
Through horizontal directional drilling (HDD) techniques, one horizontal remediation well can place the screen directly within the “smear zone” over several hundred lateral feet, even if that zone changes in elevation. Therefore, when groundwater rises, the free product and dissolved phase of contaminants are captured. After groundwater falls, massive amounts of screen continue to capture contaminants in the vapor phase.
Due to having a more effective screen-to-contaminant area of coverage, treatment times are reduced for projects involving multi-phase extraction when using horizontal remediation wells. Clients also appreciate the versatility of the installation process of horizontal wells. The drill rig can be positioned in a location that minimizes disturbances to on-site activities. As a result, the wells can be installed beneath buildings or facilities where multi-phase extraction is required, without needing to shut down business operations during the installation process.
It takes an impressive amount of screen contact to successfully implement a multi-phase extraction project. Horizontal remediation wells can provide the necessary footage and installation versatility to remove significantly more contaminant mass than traditional vertical systems.