Horizontal Wells + Vertical Wells = Site Closure

By: Tomas Will, Sr. Environmental Technical Scientist

A consultant wanted to be able to win over an important client who was faced with longstanding issues from a leaking oil pipeline.  The problem was that the site conditions made it difficult for vertical wells to target the plume. The consultant wanted to improve their chances for success in winning over their client. In order to achieve that, they needed a solution that would allow them to bring their site to closure without further delays and ballooning costs. Directional Technologies understood their frustrations and working together, helped them implement their approach of combining vertical and horizontal remediation strategies.

Background and Setting:

Our client faced the challenge of remediating three petroleum plumes along a 1,000-foot section of pipeline. The release occurred sometime in the 1950s, which allowed for the non-aqueous phase liquid (NAPL) to seep into the tight poor spaces of the relatively fine-grained silt, increasing the remediation difficulty. Previous remedial measures included in-situ injections of ORC and Persulfate. While injections were successful with initial concentration reductions, rebounded concentrations required additional remediation.

Problem:

There were three distinct plume areas surrounding the leaking section of pipeline and a remediation system consisting of multiple vertical air sparge wells was installed to implement a strategy to bring the site to closure. Data showed that two of the plume areas were being successfully treated, however, the easternmost plume was not responding as they had hoped. The equipment compound containing the remediation system was separated from the easternmost plume by a road and a stream which were limiting the placement of additional vertical air sparge wells.

Solution

The client determined that they could address this challenge and minimize construction costs by using directional drilling to install a set of horizontal air sparge wells to access the eastern plume. The horizontal air sparing components of the remediation system provided air delivery beneath the surface obstructions and directly into targeted zones that were not accessible using vertical wells. The system was initially operated continuously for the first two months of operation. Over the next two and a half years of operation, pulsating strategies were implemented and gradually increased the pulsating frequency from twice per day to 12 times per day (1 hour on and 1 hour off). Results showed increased groundwater mounding during system operations with groundwater elevation changes up to 6-inches, which expedited biodegradation of contamination. 

Through proper design, installation, and operation, the vertical and horizontal air sparging system resulted in direct control over air delivery into multiple target zones critical to the success of the project.  By combining the vertical and horizontal air sparging strategies, and optimization of the remediation system over time, the radius of influence for biosparging was increased to provide biodegradation of the majority of the contaminate plume. As a result, the client was able to treat larger volumes of contaminants, expedite the timeline to achieve closure, save costs by replacing the need for multiple additional vertical wells, and become a major problem solver for their client.

Have you had projects that have struggled to keep timelines and budgets under control when challenges arise? Call our horizontal remediation well experts at 1-877-788-4479 to discuss your current project needs.