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MIHPT
Membrane Interface
Hydraulic Profiling Tool

How MIHPT works

Tap the log chart to see what it shows.Hover over the log chart to see what it shows.

When to use MIHPT

  • Dissolved-phase plume delineation and vertical profiling
  • Petroleum hydrocarbon site investigations
  • Chlorinated-solvent site investigations
  • Mixed plume delineation (petroleum and solvents)
  • VOC source-zone characterization
  • Dense non-aqueous phase liquid (DNAPL) distribution assessment
  • VOC assessment before and after remediation
  • Lithology and permeability profiling

See the tool comparison if your objective is not here.

About HRSC

How MIHPT works

Three laboratory-grade detectors and hydraulic profiling in one push.

  • Supply line
  • Return line
  • Membrane
  • Heater block
A drawing of the MIHPT tool cut open at its heater block, not to scale, playing four steps in a loop. Heat comes off the heater block into the soil along its whole length. The VOCs near the block drift to the membrane as vapor and pass through it into the tool. Carrier gas comes down the supply line to the membrane and carries them up the return line toward the detectors at the surface. VOCs farther out in the soil stay where they are.

At each depth

How the detectors work together

The photoionization detector (PID) and flame ionization detector (FID) respond to a wide range of volatile organics. The halogen-specific detector (XSD) responds only to halogenated compounds.

Contaminant category

Relative detector response

PID

Moderate to highNone to lowModerate to highHighNot sensitive (NA)Moderate to high

FID

Low (see note)LowHighHighHighModerate to high

XSD

Moderate to highHighNot sensitive (NA)Not sensitive (NA)Not sensitive (NA)Moderate to high

Note

FID often responds in chlorinated DNAPL.

Detection of chlorinated alkenes on PID can differentiate chlorinated alkanes which don’t respond on PID.

Relative PID-FID response will vary with degree of weathering.

Other non-chlorinated VOCs may give similar response pattern.

Useful for tracking landfill gas plumes, releases of natural gas or for monitoring methane produced by anaerobic in situ bio projects.

Both groups raise the PID; the XSD, which responds only to halogenated compounds, tells them apart.

Source: ITRC, Advanced Site Characterization Tools, section 3.2 (opens in a new tab): Table 3-2, modified from Geoprobe Systems, and section 3.2.2.2 for the mixed note.

Low Level MIHPT

For trace-level VOC detection below standard MIHPT sensitivity thresholds.

Sampling mechanism

Continuous carrier gas flow

Pulsed carrier gas

Relative detector response

The same PID, FID, and XSD detectors are used. It is the sampling mechanism that changes.

  • ~10× sensitivity increase
  • PPB-level detection

Contact us to discuss how MIHPT can support your next investigation.

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