The ART In-Well Integrated Technologies combines in situ air stripping, air sparging, soil vapor extraction (SVE), and enhanced bioremediation/oxidation plus subsurface groundwater circulation. The ART Technologies are designed for installation within a four-inch or larger well. The subsurface effects of a typical ART Integrated well are depicted to the right.
The air-sparging component results in reduced water density and lifting (mounding) of the water table in the vicinity of the well. This in turn causes a net negative gradient to the well, resulting in water flowing back toward the well. This upwelling force created by the sparging results in an in-well packer concept, resulting in pressure and density gradient from the lower screened interval to the upper screened interval that assists in driving the dynamic subsurface circulation forces.
Vacuum pressure (soil vapor extraction component) is applied at the top of the well point to extract vapors from the vadose zone along with vapors from the in-well stripping processes. The negative pressure from vacuum extraction creates additional water mounding while boosting the net gradient back toward the well; it also removes vapors from the unsaturated or vadose zone and well annulus. The SVE and sparging combined in the same well further enlarges the radius of influence and boosts circulation.
A submersible pump is placed near the bottom of the well screen to circulate impacted ground water to the wellhead for downward discharge through a spray head. The water cascades down the interior of the well and system piping, providing multiple wetted surfaces for mass transfer with a high air to water contact ratio, similar to what occurs in a packed-column air-stripping tower. Enhanced stripping via an air sparging point near the bottom of the well occurs simultaneously thus increasing the air to water contact.
In essence, the well acts as a subsurface air-stripping tower, in which the pumped and stripped, dissolved-oxygen-rich water flows down the well annulus and over the mounded water back into the aquifer and vadose zone. This action hydraulically enhances the radius of influence and flushes contamination from this zone. Ultraviolet treatment units and/or the addition of ozone to the air-sparging stream are options that can be incorporated with the ART Technologies at minimal expense and effort. When these are combined, the synergistic technology effects create a circulation zone surrounding the well that further enhances cleanup and distributes oxygen into the formation.
In summary, contaminants are stripped from the water as a result of the combined effects of in-well air stripping and air sparging. The radius of results, or dynamic subsurface circulation cleaning zone, is created by a combination of negative gradient at the base of the well from air sparging, the application of vacuum extraction, and subsurface water circulation induced by a submersible pump. Although it is a site specific parameter, a radius of influence of up to ten times the water column has been achieved at sites where the ART alternative has been implemented. These different component processes are integrated in the ART Technologies and can be installed in a four-inch (minimum) groundwater well. Another primary benefit of the technology that separates it from similar remedial alternatives is its potential to treat the same unit of water as many times as necessary because of the multiple stripping passes that can be achieved.
Soil and Groundwater Remediation is Our ART