London Womack, Division Director, Plant Operations, Hillsborough County Public Utilities
Hillsborough County, Florida, is one of the fastest growing counties in the United States.
As neighborhoods pop up closer and closer to a wastewater treatment plant in northwest Hillsborough County, new residents in new communities have complained about the facility’s unpleasant smell. So public utilities officials devised a creative solution to freshen things up.
When airports, wastewater treatment plants, and other senses-stimulating facilities are built, they tend to be far from communities. But as land availability decreases and property values rise, new neighborhoods edge closer and closer to these public facilities that were intended to be out of the way.
Operations and Maintenance staffers proposed retooling a facility to treat primary sludge before it gets piped to the Northwest Regional Water Reclamation Facility (NWRWRF). Their hope was that treatment of the primary sludge generated at the River Oaks Advanced Wastewater Treatment Facility (AWWTF) on-site would help eliminate the odiferous problem until the Northwest Regional Water Reclamation Facility could expand to handle the new volume.
Modifying a wastewater treatment plant is not routine, though. Engineers needed analytics to know for sure that River Oaks AWWTF could be modified safely, and that piping approximately 150,000 gallons of treated, waste activated sludge rather than a mixture of waste activated sludge and primary sludge, daily would help alleviate the objectionable smell at the Northwest Regional Water Reclamation Facility’s biosolids management operations.
The County hired a consultant to analyze the project using business intelligence and a thorough examination of available data. The consultant’s subsequent report showed that, indeed, retooling River Oaks AWWTF to treat its primary sludge would work with minimal impact on the overall treatment plant process.
The plant would have to work harder, but it could handle it. The quality of the treated wastewater would be good.
AWWTF slightly modified its sampling schedule to ensure operational consistency and compliance following the modifications. The River Oaks AWWTF adjusted the frequency of the process control samples from three times per week to daily. With daily reports on the waste activated sludge (WAS), the team was confident in how the River Oaks facility was performing and the number of digesters in service at BMF was reduced from three to one.
The delivery schedule of WAS to the sludge holding tank and digesters was modified from sending all WAS to the sludge holding tank to bypassing the sludge holding tank and delivering NWRWRF WAS to the digester during a four-hour timeframe Monday through Friday. This schedule change had a dramatic impact on the odor. Complaints from residents near the NWRWRF biosolids management operation ceased.
Business intelligence also gave Hillsborough County Public Utilities a better idea of the cost of modifying the River Oaks AWWTF. River Oaks showed a peak energy cost increase of about $10,000 due to increased use of blowers in aeration basins. But River Oaks had significant decreases in export volume—about 100,000 gallons per day. Thus, Public Utilities’ net operating costs were about the same after the modifications.
It was the first time the department used business intelligence tools to confirm an expectation of what might happen. Sure, officials previously have looked closely at state-mandated data before taking action. But not to this extent.
The County now is exploring other means of using data analysis to test the effectiveness of projects.
It’s kind of a canary-in-the-coal-mine approach. If a deep assessment of data shows something might not work, it’s wise to change course.
Piping treated, waste activated sludge from River Oaks to the northwest plant is a temporary fix. It will be unnecessary when the expanded northwest plant is completed. At that point, the County will decommission River Oaks AWWTF.
Business intelligence practices were indispensable in helping us set up these temporary and long-term strategies.
Pleased with the outcome in this case, Hillsborough County Public Utilities looks forward to using business intelligence tools, when appropriate, to direct and support decision-making.