Increasingly, consultants are choosing to implement a more effective bioremediation approach via horizontal injection wells. Horizontal remediation wells offer the same services as vertical wells but with notable versatilities that can significantly improve a project’s remediation efficiency. A powerful application that is often underutilized is the ability to use horizontal remediation wells for in-situ bioremediation of groundwater contamination – particularly through injection processes. Injections are traditionally applied via vertical remediation wells; however, the implementation of horizontal remediation wells can significantly increase the rate and efficiency of remediation.
Most groundwater remediation designs incorporating injections involve the need to drill and install a row of multiple vertical remediation wells, often less than 10 feet apart, to create a barrier to intercept migrating groundwater contamination. Lithological conditions within the target injection interval can vary from well to well, causing an incomplete and irregular radius of influence. Many of the limitations experienced through the injections of vertical wells are overcome by the utilization of horizontal remediation wells. In these cases, the Directional Technologies team works with your team to determine the best placement of the wells in both the vertical and horizontal planes of intercept.
Direct Access to the Source
Injecting remediation amendment near the contaminant source is critical in order to prevent further downgradient migration of the plume. Using directional drilling techniques, horizontal remediation wells can be installed beneath existing buildings and below complex subsurface utilities to access the source of the plume. Design features such as blind installation (single entry) allow more flexibility to target the source area directly. This, in conjunction with Directional Technologies’ approach to custom site-specific well screen design, ensures the amendment is injected at the optimum location and efficiency – regardless of the location of the plume’s source.
Enhanced Radius of Influence
In order to create a successful amendment barrier in a traditional vertical remediation well design, the radius of influence must propagate far enough into the formation to overlap with the radius of influence of the adjacent wells in the barrier. Gaps in the amendment barrier provide conduits for contamination to seep through and continue downgradient. During the drilling process of horizontal remediation wells, the bore path is tracked in real time in order to ensure that the well screen will be expertly set within the target treatment zone. Therefore, lithologic variations that may affect the radius of influence during vertical well injections are significantly reduced since the horizontal bore path is preferentially guided to remain inside the target interval. Horizontal remediation wells provide continuity across the well screen during the injection process and ensure that the treatment zone is effectively saturated with the remedial amendment. Each well screen is modeled for flow and pressure across the screen using DTI’s proprietary software.
Less Invasive
Traditional in-situ bioremediation techniques, such as vertical well injections, often result in invasive designs and lengthy remediation timelines. Tens of injection wells, or more, may be required in order to inject the proposed amendment volume. Similarly, performance assessment results often require additional vertical wells to be installed. Often, a gap in the injection barrier or a failed injection into a poorly set vertical well (due to amendment clogging or lithologic restrictions) requires replacement wells to be installed. One horizontal remediation well can often replace several vertical wells in order to remediate the same target area, eliminating unnecessary additional well construction in the subsurface and obstructive well vaults at the surface. Directional drilling provides the freedom to establish the staging area of the drill rig and equipment to be out of the way, allowing on-site activities to continue without interruption.
Consultants are often unaware of the many applications of horizontal remediation wells. The utilization of horizontal remediation wells for injection services in the pursuit of in-situ bioremediation will enhance the efficiency of the injection process by providing direct contact with the source and ensuring a captured radius of influence. By being minimally invasive during the installation and injection process, property owners can continue business operations during remediation procedures and have less post-project restoration to consider at the closure of the project.
How can the advantages offered by decades of technological advancement in the field of horizontal wells benefit your project? Call our horizontal remediation well experts at 1-877-788-4479 to discuss your current project needs, or email us at drilling@directionaltech.com with questions, review case studies, and learn more.
By Elliott Andelman P.G., Environmental Scientist