Horizontal Wells Can Eliminate Both Real and Perceived Costs

By Tomas Will, Sr. Environmental Scientist

Remediation projects can often impact the property owner in unexpected ways, and horizontal wells can eliminate both real and perceived costs. In addition to the obvious up-front costs, remediation activity can also carry indirect costs associated with negative attention from site occupants and community members, disruptions to site activities, and damage to infrastructure. When project owners select an environmental consultant to help them address their soil and groundwater contamination needs, they look for someone who has the expertise to both achieve remediation goals and help minimize costs to their business at all stages of the project life cycle. In the case of one consultant’s commercial remediation project, they were able to effectively treat indoor air vapor intrusion while eliminating interruptions to the facility by using horizontal SVE wells.

Background and Setting:

An industrial facility had used in-ground degreaser pits as part of their longstanding operations which resulted in significant TCE and PCE-impacted soil and groundwater. The property had since been redeveloped as a commercial strip mall. The contaminant plume was located beneath the portion of the strip mall building that contained restaurants and a daycare facility. Based on environmental investigations, vapor intrusion posed indoor air quality issues for workers.

Problem:

The consultant was tasked with finding a way to effectively address indoor air concerns while also looking for ways to limit interruptions to the facility and avoid creating a negative impression among the building tenants and their customers. They began exploring designs for an SVE system but were faced with costly challenges involved with implementation due to the nature of the facility.

Challenges Posed by a Traditional Vertical Well Approach:

• Highly visible remedial construction efforts, sampling events, and O&M may be the source of elevated levels of concern for occupants of the site. The building owner was concerned that if their tenants perceived that there was contamination at the site it would lead to impacts on the business relationship with their tenants.
• Project site is occupied and remedial construction, sampling, and O&M may require disrupting day-to-day activities. Traditional remediation installation techniques would require shutting down various businesses for several days which would result in lost revenue for the building tenants.
• Damage to site infrastructure during remedial construction may be costly to repair and may cause further interruption. The daycare facility was constructed with custom floors which would have to be reinstalled, and in order to get a drill rig inside two of the restaurant’s interior spaces, it would require taking down a wall.
• Future redevelopment at the site may result in the abandonment of the remediation wells. The building owner had tentative plans to redevelop the property in the near future which would require that the wells be abandoned and then reconstructed at additional cost.

 

Horizontal Wells Were the Answer to the Challenges

The consultant had encountered similar challenges on previous projects and had used horizontal remediation wells to address those concerns. The consultant reached out to Directional Technologies to assess potential designs for a horizontal SVE system. After reviewing several possible designs, they selected an approach that would install blind (single-entry) horizontal wells from the facility exterior that could effectively access the contaminated vadose zone beneath the building slab in the center of the building.

Three horizontal SVE wells were installed at depths ranging from 6 to 9 feet beneath the building floor. The 3-inch diameter wells were installed with screens ranging from approximately 150 to 300 feet in length. The entry points for the wellheads were installed anywhere from 50-80 feet away from the building exterior to avoid being placed in visible areas of the parking lot. The horizontal installation did not require any invasive presence within the building and future sampling and O&M could be performed from the discrete wellhead area found in the rear of the parking lot.

Using horizontal wells, the consultant found they could:

• Avoid creating a negative perception from the building tenants and their tenants’ clients.
• Eliminate impacts to ongoing commercial activity during remedial construction, sampling, and future O&M, which saves their client money.
• Avoid repair costs from damaging the interior of the buildings during remedial construction.
• Reduce the total number of SVE wells required.
• Access portions of the plume beneath the facility without disrupting the tenant businesses.
• Allow significantly more screen to be placed in contact with the most highly concentrated portions of the plume, allowing for more effective remediation performance.

Conclusions:

Horizontal wells are an effective solution to win over your clients by helping them avoid negative publicity, save money, and eliminate interruptions at their facilities. With the proper equipment, techniques, and experience provided by Directional Technologies, horizontal remediation wells can be successfully implemented at sites that present restrictions that might otherwise make remediation efforts technically or economically challenging.

Do your clients have business needs that they don’t want to have impacted by remediation activity?  Call our horizontal remediation well experts at 1-877-788-4479 to discuss your current project needs.