Should Site Assessments Be Conducted Through Traditional Sampling, Groundwater Monitoring Wells, or Direct Sensing Methods?

 It is safe to say that 99% of all site assessments are either conducted through traditional sampling, groundwater monitoring wells, or direct sensing methods. As a leading site investigation partner to environmental consultants throughout North America and Hawaii, COLUMBIA Technologies specializes in soil and groundwater contamination assessments.

Since 1999, we have completed over 750 site assessments for some of the most discriminating clients including oil companies, government agencies, commercial real estate owners, developers, as well as architectural and engineering firms. Throughout all of our testing and experiences to date, we believe that using a comprehensive High Resolution Vertical Profiling approach seems to be the most cost-effective and accurate method to assess a contaminated site. This consists of direct sensing technologies to delineate the vertical and horizontal extent of the contamination to pinpoint the location. Once this information is known, following up with confirmation soil and groundwater samples would take place to validate the contaminant of concern.

The direct sensing technologies may cost more up front, however they assure that accurate information is being collected to move forward with designing remediation plans. In addition, our patented real-time data services platform, SmartData Solutions®, is able to produce high resolution visualizations through a secured website for online review of project data.

We feel that direct sensing methods are the most effective approach to site assessments for the following reasons:

  • Real-time information opposed to delayed turnaround time. With respect to soil and groundwater analyses, you don’t have to wait days or weeks typically associated with traditional sampling methods to find out your results. Direct sensing technologies are able to collect literally thousands of data points as the direct sensing probe is continuously being pushed into the subsurface. Therefore, this information can be processed in real-time providing easy to understand decision making information to the field, project teams and regulators.
  • Reduction of risks associated with traditional sampling. With traditional sampling methods you are taking a “hit or miss” approach that you may or may not collect the right sampling location. Even further, you are risking whether or not the area of concern is contained within the sampling interval which is selected. Using direct sensing to map a plume, particularly the vertical extent you are able to delineate in the subsurface layers where the contamination “lives.” From there it is highly recommended that confirmation sampling takes place in the areas where the 2D/3D visualizations indicate contamination. Opposed to gambling whether or not you are selecting the right area, direct sensing technologies pinpoint the contamination zone.
  • More data points are collected providing better information. With traditional sampling methods one would have to collect a specific section of the soil or groundwater column in intervals dependent on the length of the sampler being used. This can become quite cumbersome and time consuming especially with projects involving deeper locations. For example, if the sampler was 4 feet long, and the depth was 80 feet, 20 different pushes would have to take place at this one location. Direct sensing probes such as the (MIP) Membrane Interface Probe, (LIF) Laser Induced Fluorescence, or (HPT) Hydraulic Profiling Tool can be continuously pushed into the subsurface for a more effective and quicker site characterization. Not only do these technologies move faster, but they are able to collect more data which is valuable to the client providing more comprehensive reports.

Groundwater monitoring wells can be effective in screening various intervals for groundwater contamination, but for instance, if the contamination of concern is mobile the liquids collected may or may not include the contamination of concern. This becomes a major issue, especially with long term screenings projects, as the screening analysis indicates an inaccurate picture of a shrinking plume, where in reality, the mobile contamination has migrated to another area. For this reason, conducting site assessments with directing sensing methods enable all parties involved to make better decisions in moving forward with remediation plans based on the comprehensive investigation which took place.

How have you handled site assessments on your projects? Did you stick to just traditional sampling, groundwater monitoring wells, or direct sensing methods, or was a combination of these approaches applied in determining the concentration level of contamination? Please share your thoughts on how to most effectively assess contaminated sites.

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