At the City of Oklahoma City's Hefner Water Treatment Plant, our team developed an innovative solution for the processing of lime sludge produced as part of the water purification of drinking water at the City’s Hefner Water Treatment Plant (WTP). Prior to the construction of the project, the City owned and operated a lagoon system for lime sludge with a maximum capacity of 100 million gallons per day (MGD). Due to the high costs to maintain the lagoons, the landlocked location of the plant, and the operational issues experienced as plant flows approached 75 MGD, the City sought a solution that would allow for the abandonment of the lagoons.

Through an initial evaluation of multiple dewatering alternatives at the plant, it was determined that converting to a belt filter press mechanical dewatering system was the best solution when treatment capacity was expanded to over 100 MGD. Maintaining the current lagoon system required a 30-Year NPV of approximately $82 million; in contrast, the selected mechanical dewatering alternative produced a 30-Year NPV of approximately $62 million. The mechanical dewatering system is designed for a water treatment flow of 150 MGD with the ability to be easily expanded to 200 MGD in the future.

With an accelerated design schedule of nine months to complete construction documents, a construction contract was awarded in May of 2016. Our team provided construction administration services throughout the 24 months of construction. We were responsible for the timely review of over 400 submittals and O&M manuals, 100 requests for information, and 24 pay claims. Construction was completed in May of 2018 with final acceptance by the City in June of 2018.

The Hefner Water Treatment Plant is pivotal to the Oklahoma City Water Utilities Trust and its goal of providing
quality drinking water to the residents of the City of Oklahoma City. As part of the treatment process, lime and polymer are added in reactor clarifiers to settle out unwanted solids in the raw water. Given the existing water characteristics, it was determined that up to 430,000 pounds per day of solids could be generated at treated flows of 150 MGD. The City’s forward-thinking decision to mechanically dewater solids residuals with belt filter presses created the largest lime solids dewatering installation in the State of Oklahoma.

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Services Provided:

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• Evaluation of Multiple Dewatering Alternatives

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• Preparation of Construction Plans

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• Construction Phase Services

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