AWWA DSS60325

This slide presentation outlines information on maintaining disinfectant residuals in distribution storage tanks. Topics covered include: development of poor water quality in distribution tanks; methods to prevent it; tools including CFD modeling results; 3DLIF modeling results; empirical formulas; types of water storage; short-circuiting; mixing equation and mixing time comparison; velocity vectors - isothermal and negative buoyancy; CFD Model; maximum rise of negatively buoyant jet; terminal rise height of vertical jet; water quality problems and their causes; identifying dead zones by monitoring; temperature and Cl₂ residual data; maintaing water quality in reservoirs; guidelines on water turnover rate; basic principal for optimizing water quality within a storage reservoir; inlet configurations to avoid; inlet/outlet separation; typical duckbill manifold configuration for circular ground level reservoirs; and, hydraulic comparison duckbill to equivalent pipe diameter. Several case studies are outlined that include: Eugene Water and Electric Board, (2) 1mg reservoirs; Mashpee Water District, Massachusetts, 1mg composite elevated tank; Town of Narragansett, Rhode Island, 750,000 gallon fluted hydropillar; Shortsville, New York, 250,000 gallon standpipe; and, Lakeshore Reservoir. Information is also outlined on the 2002 AwwaRF unsolicited research proposal titled, "Physical and Numerical Modeling of Mixing in Water Storage Tanks". The AwwaRF research summary results include: multiple inlets reduce mixing times up to 35% (same momentum);with negative buoyancy, multiple inlets can mix a tank when a single inlet will not; low momentum and buoyant jets (+ or -)may never mix the tank; and,simultaneous fill & draw tanks take longer to mix.

Product Details

Edition:

Vol. - No.

Published:

09/29/2004

Number of Pages:

61

File Size:

1 file , 9.6 MB