Summary of results of testing for contamination from the historic Leadville lead and silver mine site in Leadville in June 2022.
Leadville was the site of an underground lead and silver mine from the 1890s to the 1950s.
Previous testing identified elevated concentrations of lead and other contaminants at the mine. Further investigation was needed to determine if contaminants had spread from the mine site.
We tested surface soils from road reserves and bushland in the town. The testing aimed to:
- identify if the surface soils are contaminated with lead, arsenic, cadmium, manganese and/or zinc, and
- where identified, work out appropriate response actions to protect human health.
The soil testing involved shallow digging of surface soils, a hole up to about 30–50 mm wide and 0–50 mm deep, within soft ground at each sample site (usually a roadside verge).
Using a hand-held X-ray fluorescence (XRF) analyser, which is specialist equipment to measure lead, arsenic, cadmium, manganese and zinc in the field, the EPA screened soil to get an early indication of contaminant levels. If elevated levels were indicated, soil samples were collected and sent to a laboratory accredited by the National Association of Testing Authorities (NATA) for testing to confirm the metals levels.
Additional soil samples were analysed by the laboratory for quality assurance purposes.
Twenty-six screening tests were tested using the XRF and soil from 9 of these sites were tested at the laboratory.
The comparison of results found that only one of the 26 sites in Leadville, on the roadside verge at Clarke St, had levels of lead that were marginally above the contamination threshold for public open-space land.
The site is elevated and had some indication of filling, possibly as part of road construction. The source of this fill material is unknown, however it may explain the elevated lead level.
In all other parts of the town that were tested, contaminant levels were below the relevant contaminant threshold.
This indicates that lead, arsenic, cadmium, manganese and zinc have not spread from the mine site into Leadville, and no further action is required.
Map of testing locations