By Tomas Will, Sr. Environmental Scientist

Background and Setting

The consultant was hired to help a large industrial facility deal with a groundwater contaminant plume that was spread over a wide area and was migrating toward a nearby surface water. Initial remediation designs incorporated the use of a large number of vertical air sparge wells positioned to treat the plume and prevent contamination of the surface water.

Problem

The consultant encountered multiple site conditions that raised concerns. The contaminant plume was located underneath a material stockpile area where end loader and trucks deposit and unload material at all hours of the day. Several of the planned vertical wells were in direct conflict with the paths that the loaders and trucks use to move around the stockpile area and several more were planned in the location of existing stockpiles. The proposed vertical wells would have placed significant limitations on both the short-term and long-term use of the heavy equipment and would require the relocation of massive amounts of stockpiled material.

To make challenges even greater, previous investigation of the area revealed that the shallow subsurface contained a 15-to-20-foot vertical layer of steel byproduct material. The steel byproducts consisted of a dense assortment of chunks ranging in size from large cobbles to small boulders. In addition, the proposed screen intervals required depths of greater than 50 feet below ground surface.

Solution

Recognizing that their initial designs would limit the use of the facility’s critical operations and require significant resources to prepare the area for vertical wells, the consultant went in search of an alternative approach that would allow for a successful remediation as well as spare their client from significant operational difficulty. They began work on a new design that incorporated the use of both vertical and horizontal air sparge wells which could help alleviate many of their client’s concerns. Seven horizontal air sparge wells were added to their designs which replaced multiple previously planned vertical wells

By adopting the new design, the consultant found that:

  • Horizontal wells would prevent interruptions to facility operations during horizontal well installation and subsequent operations and maintenance
  • Horizontal wells would eliminate the need for their client to devote resources to moving several of their stockpiles
  • Horizontal wells would significantly reduce the total number of vertical wells required and save money on their overall project budget
  • Horizontal wells would significantly improve the zone of influence offered by the previously proposed vertical wells
  • Horizontal wells would provide more precise targeting of hot zones
  • Horizontal wells would allow significantly more screen to be placed within the plume via the horizontal wells, allowing for more efficient air sparging

However, they still faced challenges on how they could implement horizontal wells due to the thick layer of steel material and the depths of some of the wells. Using their 28 years of expertise, Directional Technologies engineered an approach to help the consultant implement the superior design.

Results

Directional Technologies prepared various equipment configurations to address the subsurface conditions. Specially prepared drilling equipment was used to bore through the layer containing the large chunks of steel byproduct and achieve accurate drill bit tracking despite the interference caused by the steel material.  The consultant’s design consisted of over 3,200 feet of horizontal remediation wells containing over 2,800 feet of screen. Facility operations in the material stockpile area were able to continue uninterrupted during the directional drilling process and the horizontal well heads were installed out of the way of the operating areas to prevent any future limitations to the nearby operations.

Conclusions

By incorporating horizontal wells, consultants often find that they can achieve better results and avoid the drawbacks that vertical wells can sometimes present.

How could your relationship with your clients be improved by using horizontal remediation wells to overcome challenging site conditions?  Call our horizontal remediation well experts at 1-877-788-4479 to discuss your current project needs or visit our website to reach out with questions, review case studies, and learn more.