Table 11207 Comparison Of Various Leak Monitoring Techniques




Substances Detected

Relative Cost


Inventory Control


Conductivity Sensors

Electric Resistivity Sensors

Gas Detectors



Monitoring in



A system based on product record keeping, regular inspections, and recognition of the conditions which indicate leaks.

Uses a probe that detects the presence of stored product by measuring thermal conductivity.

Consists of one or series of sensor cables that deteriorate in the presence of the stored product, thereby indicating a leak.

Used to monitor the presence of hazardous gases in vapors in the soil.

Grabbing soil or water samples from area for analysis.

Monitors pressure level or vacuum in space between walls of a double-walled tank.

Any storage tanks and buried pipelines.

Can monitor groundwater or normally dry areas.

Can monitor groundwater or normally dry areas.

Areas of highly permeable, dry soil, such as excavation backfill or other permeable soils, above ground-water table.

Universal; primarily used to collect groundwater samples, as would be the case with tanks stored in high ground-water area.

Double-walled tanks.

Any product stored or transported.

Any liquid.


Any liquid.

Highly volatile liquids, such as gasoline.

Any substance

Pressure sensors monitor tank integrity and are applicable with any stored liquid. Fluid sensors monitor presence of any liquid in a normally dry area and are also applicable with any stored liquid.





The technique is widely applicable to any product stored or transported in pipelines. However, it requires good bookkeeping, and will not detect small leaks.

Primary advantage is early detection which makes it possible for leaks and spills to be corrected before large volumes of material are discharged. Typically requires Af inch of product on ground/ water interface in wet (groundwater) applications.

Primary advantage is the early detection of spills. Once a leak or spill is detected the sensors must be replaced. Can detect small as well as large leaks.

Once the contaminant is present and detected, gas detectors are no longer of use until contamination has been cleaned up.

Highly accurate intermittent evaluation tool. However, does not provide continuous monitoring.

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any double-walled tanks.

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