CDM News - May 2008 - (Page 9) Several other improvements have enhanced operations and saved money. For example, computerized controls streamline everyday functions by automatically monitoring treatment processes, system pressure, and water levels throughout the system. Two modern air-stripping towers and offgas scrubbers, which remove hydrogen sulfide from the water, have reduced tower cleaning from a daily requirement to a seasonal task. A 1.5-milliongallon pre-stressed ground storage tank increased the onsite storage capacity by 50 percent. Two new, high-service pumps enable the plant to handle a higher peak demand for drinking water. Working in tandem with the existing generator, a new electrical standby generator can meet the increased power needs and supply energy with greater efficiency. New computerized controls enhance and automate everyday functions. Comprehensive Improvements City leaders began considering plant expansion in 2002. At the time, the plant’s existing ozone treatment process offered a cost-effective, safe, and non-hazardous method of disinfecting Valdosta’s drinking water. Ozone is produced on demand and onsite, so it does not require transportation or storage of hazardous chemicals. It also leaves no taste or odor in drinking water, as some chemicals do. However, it requires large amounts of electricity, so even small efficiency improvements can yield large cost savings. For these reasons, CDM focused on making plant equipment and operations better—not necessarily bigger. To achieve these improvements, CDM created a computational fluid dynamics model of the existing ozone contact chamber to evaluate ozone diffusion with the increase in the design flow of water. Modeling determined that replacing the three existing ozone generators with two highercapacity, higher-efficiency versions would allow the existing ozone contact chambers to handle a greater amount of water without requiring a larger contact chamber volume or increasing operating expenses. “The benefit of designbuild construction is that you get a very high level of collaboration with the client, in terms of cost, operations, and construction management.” — Donald E. Maurer, P.E., BCEE, CDM vice president and client service manager The design also made sure this latest project would not limit future prospects for the plant—or the city— by including features to allow further capacity expansions up to 45 mgd. “This $19 million investment has met all of our water treatment goals and has placed us way ahead of any other community in our state,” said Valdosta Director of Utilities Leon Weeks. | Charles G. Russo 9
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