The Army has released its long-anticipated groundwater study for Badger Army Ammunition Plant, comparing possible cleanup remedies based on risk to public health. An initial review of the draft 717-page document by CSWAB quickly reveals that the study design underestimates these risks.
As part of its calculation of risk, the Army proposes an arbitrary distinction between onsite and offsite groundwater. When making its risk management decisions, the Army said it considered a cumulative cancer risk above 1×10-6 (one in a million) for offsite groundwater and a less protective 1×10-4 (one in ten thousand) risk for onsite groundwater.
However, the aquifers under and around Badger function as unified hydrogeological units and groundwater is not a static system. Contaminants found at source areas inside Badger will eventually move with prevailing groundwater flows to the surrounding community, unimpeded by the Army’s barbed-wire fence.
For two of the four groundwater contaminant plumes originating from Badger, the Army included only one form (isomer) of the explosive DNT (2,6-DNT) in its health risk calculations – however, all six isomers of DNT are found at Badger.
This omission is significant as toxicological studies indicate that when both 2,4-DNT and 2,6-DNT are present, their combined ability to increase cancer risk is more than just additive, and may be synergistic or multiplicative, according to state health officials. The federal EPA cancer slope factor for mixtures of 2,4- and 2,6-DNT takes into account this effect and results in an even more protective concentration than either isomer individually or added together.
Also missing in the Army study are DNT break-down products, actual soil data for all forms of DNT and the pending PFAS investigation.
Collectively, all of these factors contribute to the underestimation of risk to environmental health and ultimately, the amount money that the military will be required to invest in cleanup.
PUBLIC MEETING:
The Army is hosting a public meeting of the Badger Restoration Advisory Board (RAB) on Thursday, December 5, at 6 p.m. in the River Arts Center Theater at the Sauk Prairie High School at 105 Ninth Street in Prairie du Sac. The community is invited to attend.
REFERENCES:
Badger Army DRAFT Groundwater Remedy Study Nov 2019 (large file)
DNT in Private Wells Badger AAP Health Consultation WDOPH 30 Sept 2016
Public Notice on Draft Groundwater Study RI/FS Badger Dec 2019
WDOH Drinking Water Advisories HALs for all 6 isomers of DNT 2007