AWWA ACE95106

Virtually all water treatment plants that treat surface waters utilize clearwells. A continuing challenge in the design of these units is to prevent short circuiting--the almost direct flow between the inlet and outlet piping that decreases the final contact period between the water and disinfectant. Two 1-million-gallon ribbon-flow clearwells at the new Carbondale, Illinois, water treatment plant use an innovative ribbon-flow design to increase CT values and improve disinfection. This design also reduced the cost of structural strengthening required to meet potential seismic loading. Carbondale is located in Southern Illinois, 80 miles north of the New Madrid Seismic Zone. According to standards of the Building Officials Code Administrators International, Inc. (BOCA), the ground acceleration coefficient in Carbondale was estimated to be 0.15g, with a response modification factor of 4.0. Traditional baffle construction in such an area requires extensive support of concrete block walls or steel plates throughout the unit to ensure integrity of the baffle during a seismic event. Because of its simplicity, the ribbon-flow baffle can be made resistant to seismic events at a fraction of the cost of traditional baffle systems. Because the clearwells operate to the equivalent of a well-baffled tank, operators maximize contact time with the disinfectant and minimize the need for adding more chlorine earlier in the process. The Carbondale facility is thus able to achieve the following: continue using the less expensive disinfectant chlorine; strip disinfection byproducts from the treated water prior to distribution; and remain assured that they meet the mandated levels of disinfection and residual throughout the distribution system.

Product Details

Published:

01/01/1995

ISBN(s):

0898678358

Number of Pages:

10

File Size:

1 file , 340 KB