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EXHIBIT A <br /> SCOPE OF WORK <br /> INDIAN RIVER COUNTY, FL <br /> LIFT STATION PRECIPITATION STUDY <br /> GENERAL <br /> Indian River County (County) owns and operates two reverse osmosis (RO ] water treatment <br /> plants . Through the course of operation, the formation of precipitant has been observed in the <br /> odor control lift station at both facilities . This precipitation has also formed inside of the <br /> downstream lift station force mains and if left untreated has the potential to block future flow . <br /> The County has directed CDM to prepare this work order to perform a study to identify the <br /> chemistry responsible for the lift station precipitation and recommend a possible solution . <br /> SCOPE OF SERVICES <br /> The following individual tasks comprise the scope of services for this project. <br /> Task 1 — Data Request and Review <br /> Upon receipt of written authorization for the precipitation study, CDM will provide the County <br /> with a letter detailing the data requirements for laboratory chemical analysis on the flow <br /> streams into the lift stations . After reviewing the data, CDM will identify any additional data <br /> requirements, if necessary . In order to minimize cost of this project, the chemical laboratory <br /> analysis will be performed by Indian River County ' s contract laboratory services provider and <br /> paid for by the County . <br /> Task 2 — Perform Chemistry Analyses <br /> In order to determine the potential sources of this mineral precipitation, CDM will develop a <br /> mixing model using the geochemical model PHREEQC and site specific water-quality data . The <br /> PHREEQC model is a thermodynamic equilibrium program designed to model chemical <br /> speciation in aqueous solutions, determine the saturation states of solutions with minerals and <br /> gases, and predict the results of various reactions, such as dissolution of minerals and oxidation . <br /> PHREEQC Interactive Version 2 . 15 . 0, released February 2008 , will be used to evaluate the <br /> characteristics of various mixtures of blow - down water, process water and wastewater . <br /> The primary focus of this evaluation will be to determine if the mixing ratios of blow- down <br /> water, RO reject water, raw water, and wastewater in the collection system are the root cause of <br /> mineral precipitation . Based upon the results of this analysis, additional modeling will be <br /> conducted to evaluate the viability of potential engineering solutions . Potential solutions that <br /> may be evaluated , based on preliminary model runs, will include pH adjustment, feed of <br /> precipitation control compounds, and adjusting discharge feed rates to minimize the saturation <br /> indices of minerals identified as having a high precipitation potential . <br /> Task 3 — Memorandum <br /> CDM will prepare a memorandum describing the data and modeling approach . The <br /> memorandum will summarize the findings of the chemistry analyses with recommendations for <br /> remediation . The memorandum will provide a chemical perspective to the issue, but will not be <br /> an engineering design for the recommended solution or solutions . <br /> A4 j12347. docx <br />