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Kimley»>Horn PARAMETERS AT POE Page 12 Hobart and Oslo provide finished water that is characteristically higher in hardness and alkalinity concentrations for a Floridan membrane plant, this is primarily due to the quality of source water and IRCU's ability to blend. Alkalinity in the finished water provides resistance to pH changes in the system, whether it be from age, temperature, loss of residual, etc. Historically, both WTPs have shown to exhibit a degree of pH fluctuation at POE which operations has primarily attributed to the added turbidity from lime slurry feed or the SCADA's system ability to respond to set point ratios and pH trim functions. IRCU desires to maintain finished water turbidity of approximately 1 ntu and pH of 8.3. Operations has noted difficulty in achieving this target with the lime slurry system, as the pH adjustment after carbonic acid solution system results in variable turbidity values in the finished water. Furthermore, based on differing qualities of the lime slurry that is delivered, operations has had a difficult time "dialing in" a specific flow setpoint and achieving consistent pH and turbidity. Based on operational data, these values can vary from 1 - 4 ntu, all while the system is working to achieve the same pH setpoint value. This problem is exacerbated at Hobart, where operations has to essentially run two separate WTP processes with each bank of four NF trains tied to a specific clearwell. To counteract the water quality variation at Hobart, IRCU had implemented caustic feed to supplement the pH and alkalinity increase exhibited by the Cal-flo system, without the added turbidity. This process change was completed in 2016 (during Phase C of the corrosion investigation). Figures 1 and 2 demonstrate a tighter window of pH ranges at Hobart primarily due to the consistent results of caustic feed. Conversely, these figures show that Oslo is able to sustain tighter window for alkalinity and hardness, primarily because the lime slurry system is the sole source of pH adjustment. The following graphs display calcium, alkalinity, and pH values from both facilities at POE: 72