The City of Dallas Water Utilities is a not-for-profit department of the City of Dallas, providing water and wastewater services to about 2.4 million people in Dallas and 27 nearby communities. Its operations are funded solely by the water and wastewater rates paid by customers. One of the principles of the utility’s mission is to ‘continuously plan for the future.’ With doing so, the capacity of the wastewater system is regularly being upgraded and re-assessed to improve the ability of the utility to meet customers’ needs by replacing aging infrastructure.
Turn the page back to 2002. That year brought about the start of a system design upgrade process. The Dallas Water Utilities teamed up with Freese & Nichols and Odessa Pumps to evaluate options and begin to plan and design a solution for aging infrastructure and to hydraulically connect both the Dallas and thee White Rock plants, located inside the Central WWTP, to provide treatment flexibility. Over the next couple years, the groups launched a collaborative effort to analyze the features and benefits of the traditional dry well/wet well, dry pit station versus a vertical turbine solids handling (VTSH) pump layout.
Based on the calculations of initial capital cost, cost of operation and overall cost of ownership, the decision was made to go with six (6) Fairbanks Nijhuis® VTSH® pumps (2 x 1000HP and 4 x 800HP).The decision to go with the VTSH pumps meant that only a new wet well would be required, thus saving approximately $6 million in construction costs. In addition to the direct construction cost savings, installation of the Fairbanks Nijhuis pumps meant the Utility would be able to take two pump stations off line when the new influent station was commissioned.
The Fairbanks Nijhuis pumps have successfully been in operation for more than two years, and the Dallas Water Utilities treatment plants now have the capacity to pump 425 million gallons per day with a firm pumping capacity of 360 million gallons per day. Back in 2002, when the utility began planning a preliminary infrastructure upgrade, no one could have imagined that in 2015, ten years after the final design was completed, the city would be hit with a deluge that would drop more than 62 inches of rain. This would turn out to be the highest total experienced this decade, and nearly three times more than each of the previous four years.