AWWA WQTC59014

Water that is retained longer within storage has been related to taste and odorproblems, loss of disinfectant residual, and increased disinfection byproducts (DBPs).In Champlain Water District's (CWD's) case, an oscillating thermocline at the plant intake introduces buoyant waterinto system storage, possibly displacing the older water from storage into the distributionsystem. CWD modeled and reconfigured a standpipe storage tank to enhance ouroperational approach to retention time and DBP formation management. The project wasintended to model, design, build and test a standpipe mixing system. Contractedcomputational fluid dynamic (CFD) modeling visualized that stratification would occurunder existing negative buoyancy and isothermal conditions with "pockets" of higherDBP and lower disinfectant residual water throughout the tank and indicated theexistence of both a retained zone, and a turnover zone within the tank. A proposed tankmodification was modeled showing that the retained zone would likely be eliminated. Amixing system was retrofitted to the previous single inlet/outlet configuration. A grabsampling plan to investigate and understand any possible turnover zone water qualitychanges was implemented. The testing plan determined HAA5s, TTHMs, anddisinfectant residuals at several tank draw down stages during four separate trials in July2002, before tank modification, and July 2003, after tank modification, under similaroperational and raw water DOC and temperature conditions. Background data wascollected to gauge similarity in before and after tank modification background waterquality conditions. Includes 11 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/02/2003

Number of Pages:

24

File Size:

1 file , 760 KB