INNOVATIVE DEWATERING AND WATER TREATMENT TECHNIQUES FOR HYDRAULICALLY DREDGED SEDIMENT

摘要

Bay West, Inc., Stone & Webster, Inc., and the U.S. Army Corps of Engineers (USACE) are currently utilizing innovative dredge carriage water dewa-tering and treatment techniques to remediate more than 66,000 m~3 of mercury-impacted sediment at Grubers Grove Bay (GGB) adjacent to the Badger Army Ammunition Plant (BAAP), Baraboo, Wisconsin, USA. The remedial action consists of hydraulic dredging, treatment, and dewatering of approximately 8.3 m~3/min of sediment-laden dredge carriage water using geotextile tubes, and discharge of filtered water via spray irrigation on agricultural lands. The 12-m circumference, 68-m long geotextile tubes have been particularly effective in dewatering the high water content/low shear strength GGB sediments. A critical element of the sediment dewatering activities was the design and construction of a manifold and pinch-valves system connecting the dredge carriage water pipeline to the geotextile tubes. The manifold and pinch valves provided a means to easily and rapidly redirect flow of the dredge carriage water to the geotextile tubes without impeding the dredging activities. It was also determined that the addition of a cationic flocculating agent was required at concentrations of approximately 60 mg/L, to enhance the geotextile tubes' filtering effect and obtain the required filtrate water quality criteria.