These future considerations are intended to meet client, community and climate benefits. Original designs were for a two-stage carbon diversion process, but that design was altered to a hybrid design to reduce project costs. That change required the use of second stage aeration basins with larger blowers because the loading increased without the carbon diversion, meaning digestion was also changed from anaerobic to aerobic. However, the system is able to adapt to an anaerobic design in the future should conditions change, meaning initial construction would not be abandoned.
The reason for the shift to the hybrid design occurred at 75% of the design stage when environmental impacts and concerns required a change in project location. Ultimately, the city and designer discovered a site acceptable to TCEQ that would also accommodate the ultimate wastewater discharge while ensuring accessibility for trunk sanitary sewers to divert flow to the new plant.
“The site layout/design needed to be revised for the new property and a new discharge location,” Schlafer said. “All of these tasks had to be accomplished in a timely manner to keep the project within budget as delays in construction activities for any extended period of time typically lead to increased costs.”
Schlafer said LAN engaged the local contractors when the site location changed to streamline the process, optimize efficiency and minimize or eliminate the potential for extra costs. In the end, he said the project saved more than $4 million with value engineering principles in the design and bid phases.
“This approach ensured the project remained aligned with the city’s budget and construction was completed with only 0.3% in non-owner directed change orders, demonstrating our team’s commitment to budgetary discipline even amidst unforeseen challenges,” he added.
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