Replacing Aging Remediation Systems with Horizontal Well

When existing soil or groundwater remediation systems begin to falter, it presents an opportunity for clever consultants to evaluate more effective solutions for their clients. The selection of a replacement mitigation/remediation system will have consequences that may be felt for years or even decades. Experience has shown that even if the existing system functioned effectively, oftentimes there are advantages to alternative designs. Increasingly, modern horizontal wells are being used to replace the aging vertical wells of years past. There are various scenarios that present a compelling reason to evaluate replacing aging vertical mitigation/remediation wells with horizontal wells, however, here we will be focusing on two of the most common scenarios.

Scenario 1: Failing Remediation Systems:

Even the best-designed mitigation/remediation systems come with a limited lifespan. Wells can begin to fail due to a host of factors that can become increasingly costly to manage the longer the remediation system stays in operation. Many of the vertical well systems that have been in operation for decades were designed when horizontal well technology was still in its early stages. With advances in technology, engineering, and drilling techniques, horizontal wells now often outperform their vertical counterparts. Horizontal wells are frequently used to solve design challenges that cannot be easily overcome using traditional wells.

The main advantages of horizontal wells in this scenario include:

• Unparalleled access to the contaminant plume regardless of site conditions at the surface.
• Increased mitigation/remediation performance due to precise targeting of the contaminant plume, greater well screen volume in direct contact with contaminated media, and increased radius of influence.
• Fewer wells are required, leading to reduced long-term O&M costs.
• Installations of wellheads at the entry point and exit point of the horizontal installation, allowing remediation equipment to be shifted from one end of the well to the other as site conditions change over time.

Scenario 2: Converting Long-Term Mitigation Systems to Short-Term Remediation Solutions:

At some sites, it may have made sense in years past to pursue long-term mitigation for large releases that are challenging to remediate. At these sites, remediation techniques are used primarily to control contaminant plumes and prevent contamination from spreading to sensitive areas. While these systems can reduce overall contaminant concentrations as part of their operation, they are designed as a long-term engineering control rather than a remediation measure that will result in regulatory closure. These systems often represent a substantial annual operational cost that usually has no projected end date. However, consultants have been able to use horizontal wells to overcome the challenging site conditions which have historically presented barriers to realistically remediating large releases once and for all.

In addition to the advantages of horizontal wells mentioned in the previous scenario, horizontal wells present additional advantages when converting to a short-term remediation strategy, such as:

• Overcoming complex site conditions presented by infrastructure, business operations or lithology.
• Eliminate the annual costs of system operation once remediation goals are achieved.
• Avoid unanticipated future costs due to changing environmental regulations.
• Achieve regulatory closure.

Conclusions:

Decisions to install new remediation systems can have consequences that may be felt for decades. At a wide variety of sites, horizontal wells can be used to achieve better remediation outcomes that benefit timelines, budgets, and success rates.

Do your clients have aging mitigation/remediation systems? Call our horizontal remediation well experts at 1-877-788-4479 to discuss your current project needs.