General Frequently Asked Questions (FAQs)

  1. What are some of the benefits of using direct sensing before and in conjunction with traditional sampling?

Most state regulators do not accept direct sensing data directly, or alone, as a basis for making site action decisions because direct sensing of any type (MIP, LIF/UVOST®, HPT) are technologies which have been designed a qualitative screening methods opposed to quantitative measurement tools. That said, in our experience direct sensing data is almost always a section or our Client’s reports to state regulators for two primary reasons:

  1. Traditional sampling data from the site tends to correlated quite well with direct sensing data.
  2. Our high resolution 2D/3D visualizations of the horizontal and vertical extent of the contamination plume provides a clear picture of the site.

COLUMBIA almost always recommends an immediate sampling effort after completion of the direct sensing survey. Some of the benefits for conducting direct sensing before and in conjunction with traditional sampling methods include:

  • The ability to quickly delineate the source area and the horizontal and vertical extent of the contamination plume, permitting precise location and depth of sampling events and monitoring wells within the plume area. This avoids the time consuming, costly and often non-productive approach of “sampling everywhere” to obtain only the few pieces of sampling data that are meaningful.
  • Direct sensing provides a mechanism to quickly locate the source so that appropriate monitoring wells can be placed in the correct location.
  • Direct sensing will show the horizontal extent of the plume (that is, the edge of the technology’s detection limits) revealing areas outside the horizontal limit where traditional sampling must be employed for lower detection limits.
  • COLUMBIA’s high resolution data services and visualization platform, SmartData Solutions®, can incorporate sampling data along with the direct sensing data. This can also provide pinpoint locations and depths for appropriate remedial action, whether chemical injection, “dig and haul” or other methods.

It is our opinion that in most cases neither direct sensing nor sampling should be used without the other. They complement and confirm each other and together provide a more complete assessment of the site.