After nearly five years of joint planning, DTD has teamed with the global consulting firm, Arcadis, to install the first full-scale pilot test of the Arcadis horizontal reactive media treatment well (HRX Well®). This well, of a proprietary design, treats contaminated groundwater in a manner similar to that of a passive reactive barrier, or PRB. The site selected for this prototype installation was at Vandenberg Air Force Base in California.
In the patented Arcadis design, the well is packed with a specifically designed treatment media and is installed parallel to groundwater flow in a contaminant plume. A unique arrangement of well screens, separated by a blank section containing the media, allows water to enter and exit the well. Differential permeability between the treatment media and the surrounding formation, combined with head differences between the entry and outlet causes contaminated groundwater to flow preferentially through the well rather than the soil. Since the inside of the well is packed with media, as the groundwater flows through the well, it is treated, and exits the well clean. To see a 3D conceptual model of an HRX Well, click here.
Arcadis has developed a model to determine flow rates, residence times, and other critical parameters for the well design. Due to contrasting permeability, the capture zone of each well can be quite large, tens of feet or greater. The well contains no pumps and requires no external energy source – remediation is driven by in situ groundwater gradients which the well design enhances. With proper design of the well and contained media, the wells can passively treat groundwater for decades.
DTD and Arcadis jointly developed many aspects of the well configuration, from the actual well construction to internal well media components. The project, funded by an ESTCP grant, has been in development for several years. Major concepts and components of the well are covered by active and pending patents by the team. An overview of the project is available for review at the ESTCP site, here.
The installation was completed in early August, with monitoring to observe flow characteristics and remediation efficacy to occur over the next year.