Woodville North vapour intrusion testing

Some chemicals in groundwater, including TCE, can evaporate into a vapour. The vapour can migrate up through the soil and enter buildings through crawlspaces, floorboards, and cracks and gaps in foundations. The movement of vapours into a building is called vapour intrusion.

If your home is potentially affected by vapour intrusion, there are some simple and practical precautions you can take to dilute or disperse vapour (by increasing the flow of fresh air from outside to inside or below a house) and prevent vapour from rising from below the ground into the house.

Open windows and doors

Promote natural breezes by opening windowsOpening external windows, doors and vents can increase the air flow inside the house and reduce the potential build-up of vapours. Keeping windows slightly open when possible may also be effective.

Reducing the time that a house is fully closed can prevent vapour build-up, as can ‘airing it out’ when you come home after it has been fully closed.

If vapour intrusion is likely to be an issue, the most important rooms to consider ventilating are those that people spend the most time in, such as bedrooms and living rooms. You can promote the movement of fresh air by opening windows or doors at opposite ends of the house to allow the natural airflow to replace indoor air with fresh air from outside.

Under-floor ventilation

If your home has a crawlspace (the area between the floorboards and the ground), increasing ventilation through this space can reduce the amount of vapour that enters the indoor air in your house. This can be done by clearing vegetation and blockages away from ventilation points outside your home.

Ensure vents are clear to allow maximum airflow

Replace older vents with newer vents

Older style vents (often made of clay) have smaller holes and tend to not ventilate as effectively as modern steel or plastic vents. Replacing older vents with newer vents may improve ventilation within the crawlspace. Installing additional vents in the crawlspace to increase airflow beneath a home may also reduce the concentrations of vapour accumulating inside the home.

Ensure vent arrangement is effective for the prevailing wind conditions

Keeping your floor in good condition

If you have timber floorboards, you can seal the gaps with a high-quality flexible (silicon) sealant available from hardware stores to ensure there are no holes or spaces for vapours to enter from below. This can also be effective for managing the energy efficiency of your home.

If your home is on a concrete slab, inspect underneath the carpet and ensure any cracks are sealed, if feasible. If it is not possible to access areas of your floor where cracks or gaps may exist, another solution might be to reconsider how different areas of the house are used. For example, rearranging rooms where the most time is spent will minimise the use of space where ventilation may be lowest, or where the flooring gaps allow air to be drawn in from below.

You should also consider sealing the gaps where pipes enter your home, such as in the bathroom, laundry and kitchen.

Tips for the safe use of exhaust fans

Some household appliances, such as kitchen exhaust fans, rangehoods and bathroom fans, can create a suction effect by extracting air upwards and inadvertently drawing vapours in from below the house. If you have any of these appliances installed in your home, it is recommended that external windows and doors are kept open while you have them turned on. By keeping windows or doors open, air is mostly drawn in from the outside rather than from beneath the house.

Vapour intrusion testing undertaken by the EPA in the Woodville North EPA assessment area will measure indoor air, air beneath the floor, and air within the soils. Together, these measurements will show whether vapour intrusion may be occurring above safe levels.

Access to your home

Day 1 – Approximately 2 hours for the placement of air samplers and to install a soil vapour bore or pin at the property (if required and agreed by the owner). We will also ask you about your house’s construction, household products you use, and ventilation to understand household activities that may influence the testing results.

Day 10 to 14 – Approximately 2 hours to collect air samplers and sample the soil vapour bore or pin (if installed).

EPA contractor

The EPA has engaged a specialist contractor (AECOM) to complete the testing. EPA representatives will be present at all times during the placement and collection of samplers at your home. AECOM staff undertaking the works have completed all relevant EPA security checks.

Indoor air sampling

Indoor air sampling will involve the placement of small air samplers at up to five locations within the residence including the main living area and bedrooms.

The air samplers used are passive air samplers and do not make noise.

The air samplers will remain in place for 10 to 14 days and then be collected by the EPA for laboratory testing.

These samplers must not be touched or moved during the sampling.

Under-floor air sampling

Timber Floors:

For timber floors, it may be possible to install passive air samplers through existing sub-floor access doors or through external vents. Where this is not possible, other options to access the sub-floor are available and will be discussed and agreed with the owner.

The air samplers used are passive air samplers and do not make noise.

The air samplers will remain in place for 10 to 14 days and then be collected by the EPA for laboratory testing.

These samplers must not be touched or moved during the sampling.

Concrete Slab:

For flooring with a concrete slab, up to two (2) small holes may need to be drilled through the slab at discrete locations and a metal soil vapour sampling pin installed. This soil vapour sampling pin is covered with a flush mount metal cap approximately 5 cm in diameter.

Locations of the soil vapour sampling pins will be discussed and agreed with the owner.

When collecting the indoor air samplers, the EPA will collect a soil vapour sample from the metal soil vapour sampling pin for laboratory testing.

Installing and sampling a soil vapour bore

The EPA will check for underground services (water pipes, electrical and communication cables) prior to installing a soil vapour bore.

Installation will involve digging a small borehole using a hand auger (5 cm in diameter) to approximately 1.5 m below the ground surface. A metal probe will be inserted at the bottom of the hole with plastic tubing leading to the surface. The borehole will then be backfilled with sand. The soil vapour bore will be finished with a plastic cover that is flush with the ground surface.

The location of the soil vapour bore will be discussed and agreed with the owner. These are typically installed within a garden bed.

When collecting the indoor air samplers, the EPA will collect a soil vapour sample from the soil vapour bore for laboratory testing.

Indoor air samplerSumma canister for under-slab or soil vapour bore sampling

Under-slab sampling location with metal cover (5 cm diameter)

Installing a soil vapour bore with a hand auger

Soil vapour bore cover (white) in a garden area

Soil vapour bore cover (green) in a garden area

The main chemical of concern in the Woodville North EPA assessment area is trichloroethene (TCE). TCE is a colourless liquid industrial chemical that is used widely in industry for metal cleaning and in the production of products such as adhesives, lacquers, dyes, perfumes and soaps.

In the past, TCE was also used in many other applications such as removing caffeine from coffee beans in the production of decaffeinated coffee, in dry cleaning and as an anaesthetic for surgery. In the environment, TCE breaks down rapidly in air and surface water but much more slowly in soil and groundwater.

For information about the health impacts related to groundwater contamination and exposure to TCE, visit:
Chlorinated solvents in groundwater | SA Health
Trichloroethene (TCE) | SA Health