Arsenic contamination in residence downslope from an abandoned gold mine

The problem

In a residential section in Diamond Creek Victoria, unusual rainfall caused mud to slough downslope and enter a residence, causing muddy flooding. The mudslide incorporated tailings from an abandoned gold mine from the 1800s, and was contaminated with arsenic. Testing for metals contamination of the mud that entered the residence identified elevated levels of arsenic in the runoff. This was not the first time that runoff from the hill above had entered the property, though it was the most severe, and with young children in the house and a pregnant Mom, the need to establish if the property and/or the residence was contaminated with highly toxic arsenic was critical.

The outcome

Impacted areas of the property were sampled at ground level, 10 cm., and 20 cm. of depth in a structured manner to identify locations of arsenic in soil. A map to guide remediation efforts was developed for the exterior. For the interior of the building, multiple settled dust samples were taken to determine if the reservoir of settled dust in the building, to which the occupants would be exposed, also contained particulate arsenic. Areas that had not been recently cleaned were determined to be contaminated with arsenic, while surfaces that had been cleaned of dust during normal household cleaning were below the limit of detection. A complete professional clean was recommended for all surfaces once the soil had been remediated, removing the source of contamination.