A Physical Model Study of the Fairfax Off- Shore Intake in the Potomac River

To withdraw better water quality from the Potomac River for a water treatment plant during low flow conditions, Fairfax Water in VA had an off-shore river intake built in 2004. The intake was comprised of a 36-ft diameter hexagon concrete structure sitting on the bed of the river and a 10×8 ft vertical shaft connected to a 10-ft diameter pipe under the river bed. In addition, a sand barrier was built around the intake to minimize the sand withdrawal. The sand barrier is a nonagon concrete structure with approximately a 54 ft diameter.