Better Site Models with Horizontal Sampling

By Tomas Will, Sr. Environmental Scientist

When a consultant’s client reached out to them for help with an imminent property transaction worth several hundred million dollars, the consultant was placed on a short clock to help resolve lingering concerns related to contamination.

The large commercial property had previously been the site of several petroleum underground storage tanks (USTs). Before the property was redeveloped as a shopping center, the previous consultant performed an excavation to remove the leaking USTs as well as the surrounding contaminated soil. Years later, the issue of contamination in the subsurface came up during the due diligence period of a pending property sale. With the closing date for the property sale quickly approaching, the prospective buyer had concerns regarding the potential for remaining contamination. To enable the sale of the property to continue, the seller reached out to their environmental consultant to help them obtain a confirmation soil sample that could be used to verify that the property did not have remaining contamination in the subsurface.

However, the consultant was faced with a variety of challenges. The property had several busy retail tenants, and the building was located in a highly developed downtown commercial shopping district. Property management for the subject property was very sensitive to interruptions that may impact commercial activities. According to records from the previous consultant, the location of the sidewalls of the former UST excavation were located over 25 feet from the nearest building exterior. Therefore, vertical drilling to collect a soil sample from the nearest exterior wall of the building would not yield the data that was required. Furthermore, interior access to the building with a drill rig would not be possible based on the existing site conditions. With little time available to resolve their client’s issues, the quick-thinking consultant reached out to Directional Technologies for assistance.

Directional Technologies developed a plan that would allow the consultant to solve their client’s pressing problems. To accomplish this task, Directional Technologies would make use of proprietary horizontal sampling tools developed and refined to enable environmental consultants to screen soils during the installation process of horizontal remediation wells. These specially designed tools have been developed to collect soil samples that were previously considered impractical or impossible. Coordinating with the consultant, the city engineering department, and property management, a plan was formed to obtain the soil samples by taking advantage of the capabilities of horizontal drilling. The plan would allow soil samples to be collected from the target intervals while managing to eliminate interruptions to commercial activities and allow all lanes of traffic to remain open at the busy cross-streets.

Directional Technologies mobilized to the project site within a week of being contacted for this urgent project.  The equipment was staged on the sidewalk near the building exterior where it was not blocking access to any of the retail tenants. Using horizontal drilling techniques, the bore was advanced to the target location, located approximately 18 feet below ground surface in the center of a high-end retail store. A handheld walkover locating unit was utilized to track the drill bit as it passed beneath the retail spaces. Using a specialized horizontal soil sampling tool, soil samples were collected from the sidewall of the historical excavation. The consultant prepared the soil samples for expedited laboratory analysis and the borehole was subsequently grouted to the surface. The drilling equipment was in and out of the subject property within the span of a single day and the consultant was able to have their sample analyzed in time for the impending closing date for the property transaction.

Do your projects need soil sampling or remediation wells in areas that are hard to access? 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.