The new 33B pump station involved the construction of a sunk in place caisson for the wet well followed by the adjacent dry well. The first 11 foot tall section of the 18 foot by 22 foot cassion was construction on grade and then the soil was removed beneath of is thus allowing it to sink into position. The next 12 foot tall section of caisson was cast in top of the first section and then the excavation continued until the full height of the caisson was sunk into position. At this time the entire inside of the caisson was filled with ground water as the water table was just a few feet below the original ground surface and the site could not be dewatered due to its proximity to a lake shore. A mud mat and invert slab was then cast underwater, the lid of the wet well was cast above the standing water, and then the wet well was pumped out and the mechanical equipment installed.