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ATTACHMENT A INDIAN RIVER COUNTY DEPARTMENT OF UTILITY SERVICES HOBART WTP POST FILTRATION IMPROVEMENTS, ALTERNATIVE ANALYSIS IRCDUS PROJECT ID 12.24.504 I. BACKGROUND Indian River County Department of Utility Services (County) operates the Hobart Water Treatment Plant (WTP) to provide potable water service to its customers. The WTP has a capacity of 11.4 MGD and an average daily flow of approximately 7.0 MGD. The raw water source for the WTP is groundwater from the Upper Floridian Aquifer. At the Hobart WTP, it undergoes pretreatment, membrane treatment (nanofiltration), degasification and the addition of chemicals for stabilization, disinfection, remineralization, and pH and alkalinity control of the treated water. The Hobart WTP is configured such that there are two (2) sets of process equipment which mirror each other ("north" and "south" systems). Each set consists of four (4) nanofiltration skids, dedicated to a specific clearwell, for a total of eight (8) nanofiltration skids and two (2) clearwells at the WTP. A bottleneck has been created with the operation of the Hobart WTP when maintenance or downtime of one of the clearwells is required. The transfer pumps for the Hobart WTP are all situated on the south clearwell, which does not allow individual operation of the north system if the south system requires maintenance. Individual clearwells cannot be cleaned if required without impacting operation and system downtime. Another operational concern with the existing configuration of the Hobart WTP is that the north and south systems do not allow for individual operation of nanofiltration skids on either side of the system without having to run the entire post treatment system, including the degasifiers, transfer pumps, chemical feed systems and other related equipment. The County has a desire to combine the operation of the north and south systems into one, integrated WTP. This includes, but is not limited to, simplifying maintenance (clean either clearwell without having to shutdown the entire system), operating all nanofiltration skids together as one WTP, and having the ability to control both systems from SCADA. The County would also like to optimize the efficiency of the existing scrubbers and add instrumentation and control improvements to the chemical feed systems (carbon dioxide, lime, caustic and sulfuric acid). The County has requested an alternatives analysis from Tetra Tech, where different alternatives will be presented in a technical memorandum format to the County for consideration of implementation at the Hobart WTP. The alternatives analysis will include evaluations from different disciplines including civil, process, structural, electrical and instrumentation and controls. The professional services described herein will be performed in accordance with the Continuing Contract Agreement for Engineering Services, dated May 2nd, 2023 between Indian River County and Tetra Tech, Inc. JCR/pt/IRCDUS Project ID 12.24.504 Tt #200613 Indian River 1 11/12/24 OTETRATEGH