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Kim ey>>> Horn Page 8 compliance with respect to the lead and copper testing regimes, confirm treatment operating protocols are working and determine, what, if any, protocol changes are needed. Indian River County Utilities (IRCU) owns and operates a consolidated water system that treats and pumps potable water to customers from two regional membrane softening water treatment plants (WTPs). The southern portion of the County is served by the South Oslo Road WTP currently has a capacity rating of 8.57 MGD, consisting of 6 MGD nanofiltration (NF) permeate and 2.57 MGD of raw water bypass blend. There are four (4) NF trains that treat brackish groundwater from seven (7) Upper Floridan Aquifer (UFA) wells. Post-treatment stabilization is achieved through combination of raw water blend and chemical addition, utilizing carbonic acid solution and lime slurry addition. Caustic feed for pH and alkalinity adjustment is in place but not currently in service. Fluoride is also added to the finished water for consumer health benefits and free chlorine is utilized for disinfection. Oslo has historically operated with a raw water blend of 30 percent of the plant's capacity; however, due to formation potential of disinfection by-products (DBPs), particularly of bromide species, this blend ratio has been reduced over time, further reducing the contribution of hardness and alkalinity from the raw water. This reduction in blend flow rate, although beneficial to finished water quality, results inadvertently in treatment capacity reduction. IRCU has an active project to increase WTP capacity to 9 MGD with 7.5 MGD of NF permeate and 1.5 MGD of raw water bypass, reducing the blend ratio to 17% blend. This project will include multiple improvements to the WTP, most notably to the membrane softening trains, process piping, high service pumps, and chemical systems. Project is anticipated to be completed by winter 2024. The northern portion of the county is served by the North Hobart WTP which has a capacity rating of 17.14 MGD. Due to permitted limitations associated with concentrate disposal to Spoonbill Marsh, the WTP is truly limited to 11.44 MGD capacity. Hobart consists of eight (8) NF trains that treat brackish water from nine (9) Upper Floridan Aquifer (UFA) wells. Similar to Oslo, post-treatment stabilization consists of raw water blend, and chemical addition of carbonic acid, lime slurry and sodium hydroxide addition. The plant is configured such that there are two banks of NF trains (North and South) and two clearwells (East & West), where each bank is dedicated to a specific clearwell. This configuration has let to operational hurdles towards maintaining a finished water quality. Hobart has historically maintained a raw water blend of 30 percent of the plant's capacity but has reduced blend flow percentages to reduce DBP formation potential in the finished water. The existing post-treatment stabilization system serves to supplement the reduction in hardness and alkalinity otherwise gained through raw water blend. The goal of the membrane softening water treatment process is to produce water that is free of salts, low in hardness and organics. In doing so, other more desirable constituents, such as hardness and alkalinity, are removed from the water, leading to a less stable finished water quality. These types of characteristics in membrane permeate water quality warrant post-treatment stabilization processes which add chemicals back into the water to produce a less corrosive, slightly scale -forming and aesthetically pleasing water to consumers. Post-treatment of nanofiltration (NF) permeate is especially necessary for compliance with the United States Environmental Protecticn Agency's (USEPA) Lead and Copper Rule (LCR). The LCR establishes action levels of 0.015 mg/L for lead and 1.3 mg/L for copper at consumer's taps and requires corrosion control measures be implemented if more than 10 percent of the tap water samples collected during any monitoring period exceed these levels. Post-treatment stabilization is therefore necessary to inhibit corrosion and preserve the distribution system. mm