In response to public comment on the available options or technologies that may be effective at preventing the transfer of ANS through aquatic pathways in the Chicago Area Waterway System (CAWS), new information was added to the ANS Control Paper, and the final version was released April 18.
USACE received over 190 comments on the initial ANS Control Paper during the 60-day public comment period that ran from Dec. 21, 2011 to Feb. 17, 2012.In the category of "Lethal Temperature", three new control methods are outlined, including: 1) freezing, 2) carbon dioxide pellet blasting and 3) desiccation (drying).
"Carbon dioxide (CO2) pellet blasting is similar to sand blasting," said GLMRIS Technology Team Lead Johnna Potthoff, "except that frozen CO2 pellets are used instead of sand." CO2 pellet blasting leaves no blasting medium residue because the CO2 pellets turn into a gas at room temperature. CO2 pellet blasting works by flash-freezing the target organism, both killing it and making it brittle and easier to remove. This technology may be best applied where vessels can be removed from the waterway, and may not be immediately relevant to in-water applications.
The team has also expanded the discussion of predatory fish in the "Biological Controls" category to include fish that eat mollusks and added a new sub-section to the "Benthic Barriers" category regarding the use of silt as a type of sediment-surface barrier.
Public input is an important element of the GLMRIS study process, and the team is grateful to everyone who took the time to review the draft inventory and submit comments to make this a thorough inventory of potential controls.