Tests have discovered 1,4 dioxane in Park Brook, flowing from the dump site downstream into Sally’s Pond, which flows into Ringwood Creek, then discharging into the Wanaque Reservoir. 1,4 dioxane is a colorless and man-made chemical; long-term effects of exposure include liver and kidney damage, and cancer. According to the EPA’s Technical Factsheet, this chemical “may migrate rapidly in groundwater, ahead of other contaminants.” It is difficult to remove it from water or to decompose it in water due to its high water solubility and non-volatility from water, although oxidation and granular activated carbon processes have proven effective in some cases (Zenker et al., 2003).
The February 2018 Superfund site Factsheet indicates that the highest level of 1,4 dioxane was found in the Peters Mine Air Shaft at a depth of 230 feet below the surface, and was found in 17 monitoring wells in the area, as well as in 2 wells near Canon Mine (TASC Factsheet, 2018). The report concludes that “it appears that there is little risk that site contaminants will affect drinking water from the reservoir. However, 1,4-dioxane contamination is not properly defined in the deep bedrock and it is not clear whether it extends off site.” This is because it is unknown whether even the furthest well (RW-15D) goes deep enough to allow for testing in the deep bedrock groundwater. The September 2018 report by Cornerstone suggests that “Monitored Natural Attenuation” (MNA) would be enough to deal with this deep problem. MNA includes routine, active monitoring of groundwater quality and the natural attenuation processes that are expected to reduce chemical concentrations in groundwater over time. They claim MNA would be an effective solution since there is “no significant potential risk to human health” from water on the site since it currently is not used as a potable water supply, and there is “no unacceptable ecological risk to surface water based on COC concentrations in comparison to EBSLs [Ecologically-based screening levels] …”(2018, p.39).