Speeding down the Data Highway

Interpreting analytical data collected from our process streams during operations is sort of like driving a car forward, but only being able to look at the rearview mirror.

During operations at our thermal remediation sites, TerraTherm routinely collects a variety of process vapor (whole air canisters/bottle-vacs, and/or solid adsorbent tubes) and liquid samples.  The exact sampling and analytical methods used vary from site to site; each site is truly unique with different combinations of subsurface contaminants, site geology/groundwater chemistries, heating approach, as well as site specific cleanup goals and permitted discharge limits.

Process vapor sampling using solid adsorbent tubes

These process analytical data are used to:

  • Evaluate project progress versus design;
  • Estimate mass removed from the subsurface;
  • Evaluate performance of treatment equipment; and,
  • Confirm compliance with effluent discharge permit requirements.

 

 

Since we are already looking in the rearview mirror to analyze the analytical data, getting late analytical data is a problem.  Adding to the complexity of evaluating analytical data at thermal remediation sites is the fact that by the time you receive analytical results on a standard turnaround time (typically around one-two weeks), the conditions onsite and in the treatment system may have (sometimes dramatically) changed. Unlike routine monitoring or site investigations, analytical data from thermal remediation sites do not represent a static system. The subsurface (and more importantly the composition of what we are extracting from the subsurface) may change on a daily basis.  As subsurface temperatures increase, various other processes take place including boiling, steam stripping, physical displacement, volatilization, dissolution, pyrolysis, and hydrolysis. As these processes take place, the composition of the vapor and liquid extraction streams from the subsurface change.

So how can we drive the car looking forward instead of using the rearview mirror? The key is the strategic use of field analytical techniques. TerraTherm utilizes several field screening instruments, real time monitoring devices, and field test kits in order to get a handle on what is happening at any particular moment and proactively manage onsite systems.

Real time instruments such as an FTIR can be used very successfully. Many of our projects also utilize other real time extractive vapor measurement instruments such as lower explosive limit monitors and/or flammability analyzers and oxygen sensors.

Handheld vapor monitoring instruments such as photoionization detectors (PIDs), flame ionization detectors (FIDs), dust monitors, gas detection tubes and four-gas meters are used routinely to spot check vapors at various locations through the treatment process.

TerraTherm staff conducting vapor screening with a Photoionization Detector (PID)

TerraTherm staff conducting vapor screening with a Photoionization Detector (PID)

For the liquid side of the treatment process, headspace volatile organic compound (e.g. PID) readings, pH/dissolved oxygen/oxidation-reduction potential/turbidity measurements, colorimetric/drop kit titration based test kits (e.g. for metals), immunoassay test kits (for polychlorinated biphenyls/herbicides), dip slides/field tests (for bacteria/fungi), and simple indicator strips (for various water quality parameters) may be used, among other techniques.

TerraTherm routinely designs monitoring plans tailored to gather real time information, as well as collect analytical samples to fine tune our estimates, confirm our real time readings and observations, and provide appropriate documentation that we are in compliance with discharge regulations.

About Alyson Fortune

Ms. Fortune is responsible for managing thermal remediation treatability studies and project laboratory interactions, conducting reviews on laboratory data, maintaining complex field equipment monitoring systems (FTIR), and other data management functions.
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