VERTICAL AND HORIZONTAL MIGRATION OF METAL CONTAMINANTS FROM ILLEGAL GARBAGE BURN PILES IN WEST HAVEN, VERMONT

Illegally dumped and burned garbage piles have existed for years along a stretch of the Poultney River in West Haven, Vermont, on land owned by the Nature Conservancy. Analysis of ash and soil samples from different burn piles over several years shows elevated levels of many contaminants, including arsenic, copper, lead, zinc, chromium and cobalt, often exceeding background levels by orders of magnitude. The area is seasonally flooded, resulting in both erosion and deposition. Periodically old burn piles get washed away, and contaminated soil gets covered by new sediment. Vertical and horizontal sampling along a transect from one burn pile to the river was accomplished in June, 2015. Geochemical analysis suggests that contaminants have migrated downward into the underlying soil, as well as laterally towards the river. A 90-cm core from the center of the burn pile shows that metal concentrations are highest from the surface of the pile to a depth of approximately 60 cm down. (Highest values: Pb = 5000 ppm, Zn = 20,000 ppm, As = 1000 ppm, Cu = 4000 ppm, Cr = 2200 ppm and Co = 200 ppm.) This includes ash in the upper 30 cm, and underlying soil beneath the ash. At a distance of 2.1 m from the center of the burn pile in the direction of the river, a core 35 cm long shows metal concentrations highest at the bottom of the core (Pb = 2100 ppm, Zn = 1700 ppm, As = 80 ppm, Cu = 475 ppm, Cr = 215 ppm). A further 2.9 m toward the river, a 40-cm core shows metal contamination spiking at a depth of 15 cm, although at lower concentrations than the previous core. Another 2.5 m toward the river, a 20-cm core shows metal concentrations highest at a depth of 15-20 cm, again at lower amounts than the previous core. A 30-cm core taken underwater in the riverbed 5 m from the previous core showed no elevated metal concentrations. This suggests that contaminants have migrated away from the burn pile both vertically (presumably by water percolating from the surface) and horizontally (by overland flow, interflow, or both). The different relative concentrations of individual metals from one core to another may be the result of differential solubility and transport mechanisms. Contaminants ultimately end up in the river, which flows into Lake Champlain 2 km downstream.