After Barrier I, the demonstration barrier, proved successful, Smith-Root was engaged to design and construct a permanent barrier across the Chicago Sanitary and Ship Canal. The final design split the permanent barrier into two parts IIA and IIB. IIA was funded and began construction in 2006. Electrodes for both IIA and IIB were installed in the 2A contract. They consisted of bundled billets of steel 5 inches x 5 inches flash-butt welded on site, and lowered onto concrete sleepers. IIA has a wide array 66 feet long targeted at large fish, and an adjacent narrow array 38 feet long with a higher field strength for smaller fish. Three pulsators provide redundancy.
Similar to Barrier I, particular challenges were the size of the canal, the need for a long field because of the barges, high and variable conductivity of the canal water, canal water temperatures, and the unavailability of the canal walls because of barge movements. The pulsators required a large power supply system and custom electronic switches that were cooled by water circulated from the canal through heat exchangers.
Essentially complete by 2006, the barrier started regular service in 2009.
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