Abs: Real-time measurement technologies include any data generation method that enables reliable measurement or collection and analysis of environmental media in a time frame that facilitates execution of a DWS. These measurements typically result in a much greater density of information and are available to direct field activities in time frames shorter than those commonly achieved with conventional sampling and analytical methods.
Real-time measurement technologies include any data generation method that enables reliable measurement or collection and analysis of environmental media in a time frame that facilitates execution of a DWS. These measurements typically result in a much greater density of information and are available to direct field activities in time frames shorter than those commonly achieved with conventional sampling and analytical methods.
Real-time measurement technologies are used to focus when and where collaborative sampling and analyses can provide the greatest benefit. In a collaborative data set, high-density, real-time measurement screening data are supported with confirmation sampling and fixed-base laboratory analyses performed at a subset of key sampling locations. This reduces laboratory analytical costs and enables the site team to make field-decisions in real-time based on defensible analytical results supported by the weight-of-evidence of large quantities of relevant screening data. The decision logic for guiding HRSC sampling, collecting follow-up confirmatory samples and performing other sampling governed by the DWS, are documented in the investigation work plan.
- Membrane Interface Probe with Electrical Conductivity (MIP/EC)
a multipurpose tool for mapping soil and groundwater contamination, specifically volatile organic compounds (VOCs), such as halogenated solvents and petroleum compounds, and for measuring soil electrical conductivity (EC).
The Membrane Interface Probe with Electrical Conductivity (MIP/EC) is used for field screening to
rapidly map dissolved phase petroleum and chlorinated solvent contamination. The MIP/EC will quickly delineate both the horizontal and vertical extent of dissolved phase contamination and identify areas of highest concentration. The MIP/EC can be used in saturated or unsaturated zones. On average, 150 feet of MIP logging can be completed per day.
MIP is a continuous volatile organic compound (VOC) sampling system that heats the soil, water, and vapor matrix as it is driven into the subsurface. The VOC mass that is extracted across a permeable membrane is carried to the surface by an inert purge gas via small diameter inert tubing. At the surface, the VOC mass is passed across a chemical detector suite to provide a correlation between contaminant detection and the depth of the probe at the point of detection.
Standard MIP sensor detection system utilizes three laboratory grade detectors in its sensor detection system: a Photo Ionization Detector (PID), a Flame Ionization Detector (FID) and an
Electron Capture Detector (ECD).
Just like in the laboratory each detector has a different sensitivity and linear range for various
chemical compounds. In general, the PID and FID provide excellent response to VOCs such as
benzene, toluene, ethylbenzene, and xylenes (BTEX) compounds typically found in petroleum
product, such as gasoline and diesel fuel. The ECD detector is highly sensitive to chlorinated
or halogenated compounds, and is much more sensitive than the XSD for certain compounds
such as tetrachloroethylene/trichloroethylene (PCE/TCE). However, the ECD also has a limited
linear range and can saturate at lower concentrations (for PCE/TCE). The XSD detector
will see a larger range of halogenated compounds and is a better responder for degradation products than the ECD. Many common chlorinated compounds will also respond on the PID depending on the compound ionization potential.
Use of multiple detectors is important for separating different zones of contamination such as
petroleum (retail gas station) from chlorinated (dry cleaner). The complementary range of performance of the different detectors enables the system to function from low contaminant levels to near NAPL levels.
The MIP probe has an integrated Electrical Conductivity (EC) array to provide indication of general soil particle size which can help determine zones of sands, silts, and clays. Using the EC logs you can define zones of lower conductivity which allows the movement of contaminants into the subsurface.
- Laser Induced Fluorescence (LIF)
a Non-Aqueous Phase Liquid (NAPL) mapping tool used to delineate the depth and lateral extent of free product and residual phase petroleum contamination.
The Laser Induced Fluorescence-Ultra-Violet Optical Screening Tool (LIF-UVOST®) system is used to delineate the depth and horizontal extent of free product and residual phase petroleum hydrocarbons contamination. On average, 200 feet of LIF logging can be completed per day.
The principle difference between UVOST® and previous systems is the use of an excimer laser rather than a solid state laser and the integration of the lasing and detecting systems into a compact,
user-friendly package. Use of the excimer laser and the system integration provides greater reliability, better reproducibility, and less room for operator error. The fiber optic‐based fluorescence system is deployed with standard direct push technology (DPT) or cone penetrometer (CPT) equipment. All LIF systems use a laser to send pulses of monochromatic light down a fiber optic line to a probe where the light is emitted and excites any polycyclic aromatic hydrocarbon (PAH) containing compounds in the subsurface, causing them to fluoresce with a characteristic waveform signature. Using UV excitation we can detect gasoline, diesel and jet fuel; kerosene, motor oil and cutting fluids, hydraulic fluid, and crude oil.
The induced fluorescence from the PAHs is returned over a separate fiber optic line to the surface where waveforms are viewed using a detector system. The peak wavelength and intensity provide
information about the type of petroleum or potential interferences. Applying LIF allows one to gain knowledge on different types of Light Non-Aqueous Phase Liquids (LNAPL) by separating fuel signatures.
LIF-UVOST® can be used on site with a Hydraulic Profiling Tool (HPT) probe to enable project decision makers to understand the details of soil permeability leading to LNAPL mobility and migration. Deploying both LIF-UVOST® and HPT during the same investigation would provide multiple lines of
evidence with only one mobilization. LIF-UVOST® and HPT technologies are deployed on two separate tooling strings. Combining HPT information with LIFUVOST® information enables project decision makers to select sampling locations while the field work is underway eliminating the costly delays associated with traditional investigation tools and approaches. The permeability information is also critical to selecting remedial alternatives and properly placing injection, extraction, and
monitoring well screen intervals. Additional information on HPT can be found on pages 5 and 6
of this Tool Guide.
- Hydraulic Profiling Tool (HPT),
provides direct pressure response measurements of hydraulic permeability and flow to determine migration pathways, remediation injection regions, and placements for groundwater monitoring wells.
The Hydraulic Profiling Tool with Electrical Conductivity (HPT/EC) uses direct pressure response measurements of hydraulic permeability to determine migration pathways, remediation
injection regions, and placements for monitoring wells. On average, 150 feet of HPT logging can be completed per day. The pressure response of the soil to injection of water is measured to indicate the hydraulic permeability. Real-time continuous data can be produced in both fine and coarse grained material with saturated or unsaturated conditions.
The system consists of two sensors:
[Symbol]A sensitive downhole transducer to record dynamic pore pressure
[Symbol]An electrical conductivity sensor providing information on lithology
While most soil profiling methods infer permeability from parameters like grain size or geotechnical
properties, the HPT system can measure continuous data on hydraulic permeability directly by injecting water into the formation. Additionally, HPT can conduct static dissipation tests at individual depths. This data is used to determine static water level (or head pressure in confined aquifers) and hydraulic conductivity.
The HPT probe can be used on site with a LIF or MIP probe which enables project decision makers to
understand the details of soil permeability leading to contaminant mobility and migration. Deploying HPT with LIF or MIP during the same investigation would provide multiple lines of evidence with only one mobilization. Combining HPT information with LIF or MIP information enables project decision makers to more cost effectively select sampling locations early eliminating the costly delays associated with the traditional investigation tools and approaches. The permeability information is also critical to selecting remedial alternatives and properly placing injection and extraction intervals. The HPT probe has an integrated EC array to provide indication of general soil particle size which can help determine zones of sands, silts, and clays. Using the EC logs you can define zones of lower conductivity which allows the movement of contaminants into the
subsurface.
