Optimizing treatment processes to meet DBP limits
The City of Athens, Texas’ distribution system exceeded disinfection by-products (DBPs) limits, which prompted the City to review the coagulation/sedimentation and disinfection processes in the water treatment plant (WTP). The City received a notice from the Texas Commission on Environmental Quality (TCEQ) requiring additional sampling to characterize the raw water to comply with the City’s Long-Term 2 (LT2) Rule. So, Garver developed the City’s LT2 Sampling Plan with the LT2 Source Worksheet and sampling schematics indicating where the samples should be taken.
The second project phase involved evaluating the WTP’s current disinfection process, determining any available adjustments to the chlorine injection point or clearwell baffling, identifying multiple contact time strategies for plant operation, and designing new chemical feed systems.
The final program aspect involved bench-scale testing to select and optimize coagulant dosing, which included evaluation of improvements to the existing disinfection process. This would reduce distribution system DBP formation and address previous HAA5 exceedances.