Soil Vapour Extraction Safety

Soil vapour extraction (SVE) removes volatile organic compounds (VOCs) from contaminated soil using vacuum.
A network of extraction wells and pipework draws contaminated air from the subsurface for treatment.
Extracted vapours may be flammable and toxic, requiring treatment before discharge to atmosphere.
Common treatment methods include activated carbon adsorption, catalytic oxidation, and thermal destruction.
SVE systems operate under vacuum — sudden loss of seal can release contaminated vapour at the wellhead.
Workers may be exposed to benzene, toluene, trichloroethylene, and other hazardous VOCs during operation.
Electrical equipment in the SVE compound must be suitable for potentially explosive atmospheres (ATEX).
Regular monitoring of extraction rates, vapour concentrations, and treatment efficiency is required.
Maintenance of SVE wells, blowers, and treatment units involves working with contaminated components.
Environmental permits govern the operation of SVE systems, including discharge limits for treated air.

Toxic exposure	VOCs extracted from soil include known carcinogens like benzene — inhalation causes serious long-term health effects.
Explosion risk	Flammable vapour concentrations in SVE pipework and treatment units can reach explosive levels.
Environmental compliance	SVE systems must operate within permit conditions to prevent air pollution from treated discharge.

Do

Don't

Complete a COSHH assessment covering all VOCs identified in the contamination profile
Monitor vapour concentrations at wellheads and treatment units during operation
Ensure ATEX-rated electrical equipment is used in zones with flammable vapour risk
Wear RPE when working near extraction wells, pipework connections, or treatment units
Check treatment system efficiency regularly to confirm discharge meets permit limits
Maintain SVE wells and pipework seals to prevent uncontrolled vapour release
Brief all operatives on the specific contaminants present and required precautions
Record all monitoring data and maintain it for environmental permit compliance
Ensure fire suppression equipment is available at the SVE treatment compound
Carry out maintenance on SVE components using gloves and skin protection

DON'T work near open SVE wellheads without monitoring vapour concentrations first
DON'T use non-ATEX electrical equipment in areas with potential flammable atmosphere
DON'T ignore headaches, dizziness, or unusual smells near SVE operations
DON'T open SVE pipework connections without depressurising and monitoring the atmosphere
DON'T discharge extracted vapour to atmosphere without passing through the treatment system
DON'T allow smoking or naked flames within the SVE compound or near wellheads
DON'T skip monitoring of treatment efficiency — permit breaches carry serious penalties
DON'T handle contaminated SVE components without PPE including chemical-resistant gloves
DON'T leave SVE systems running unattended without remote monitoring and alarms
DON'T enter the SVE compound without signing in and reading the site safety briefing

See also: Contaminated Land Safety Awareness | Ground Gas Monitoring

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