Howard F. Curren Advanced Wastewater Treatment Plant
City of Tampa, Florida

The Early Years: Since the late 1940's, Greeley and Hansen has been the City of Tampa's primary engineering consultant for design and planning at the Howard F. Curren Advanced Wastewater Treatment Plant (formerly Hookers Point AWT Plant). As the City itself grew into a major metropolitan area, we have provided assistance to the City's Sanitary Sewer Department in many ways. In the early years, Greeley and Hansen provided not only planning and design services, but also organizational strategies that have developed into the present Sewer Department. In the late 1940's a series of designs were completed to provide the City with their first treatment plant on a partly man-made peninsula named Hookers Point. The first plant was a primary treatment plant with anaerobic digestion that grew to a capacity of 36 mgd.

Urbanization Begins: In the 1970's, urbanization and growth was on the move and, as a result, the water quality within Tampa Bay was deteriorating and the primary treatment plant was no longer adequate. Studies showed that nutrients from the treatment plant were a significant factor to the degradation of water quality. As a result, the City called upon Greeley and Hansen to provide engineering services to expand a 36-mgd primary treatment plant to a 60-mgd advanced wastewater treatment. These services included design, inspection, and full construction services. The resulting plant featured a two-stage activated sludge system using pure oxygen and deep-bed denitrification filters. Greeley and Hansen worked with a manufacturer to develop and test the denitrification filter process prior to the full-scale design. The result of the upgraded facility was that Tampa Bay realized a significant environmental improvement. Ecosystems of this once stressed bay began to flourish as effluent levels of BOD, suspended solids, and total nitrogen, have been consistently in the 3 mg/1 range or better.

Continued Growth: Even during expansion of the plant to 60 mgd, Greeley and Hansen prepared a Facility Plan in 1980 that remains the planning model used by the City for determining where major force mains and pumping stations should be located. In 1989 Greeley and Hansen supplemented the Facility Plan with what was called the Master Plan. Both plans recommended expansion of the plant to 96 mgd. As growth caused the flow to the plant to approach 60 mgd in the late 1980's, Greeley and Hansen provided design and construction services for an expanded AWT plant. The resulting facilities include the following:

  • Pre-aeration for hydrogen sulfide stripping and odor control. Hydrogen sulfide levels influent to the odor control system sometimes approach 1200 mg/L.
  • Step-feed improvements to oxygen activated sludge reactors and conversion of the facilities to the first stage of a two-stage system.
  • Conversion of aerobic digestion tanks to wastewater reactors using fine bubble diffusers. The converted tanks serve as the nitrification stage following carbonaceous treatment in the first-stage, oxygen system.
  • New deep-bed denitrification filters.
  • A major expansion to the plant's maintenance building.
  • A new 27,000-sf administration building to house laboratories and plant administrative offices.
  • A standby power facility with four 2000-KW engine generators.
  • Co-generation facilities featuring five 500-KW engine generators using sludge gas as the fuel.
  • Digested sludge is dewatered using belt filter presses and converted to biosolids using heat drying.

One of the key design features of the plant is the philosophy of providing flexibility. For example, the oxygen activated sludge system can be operated in parallel or in series with the conventional activated sludge system. Also, denitrification at the filters can be supplemented by denitrification in the activated sludge system. This flexibility allows the operators the tools to adjust to various conditions.

Other Services: The City has selected Greeley and Hansen to design major portions of the collection and transmission system, from collector sewers to key pumping stations. Greeley and Hansen assisted the City in development of budgets and rates, including special user charges. Greeley and Hansen recently assisted them in permit negotiations with the state. Recently we also participated in a study for the City with regional significance to determine if the reclaimed water from the Howard F. Curren AWT plant could be further treated and discharged to the City's potable water supply. This project was carried out through preliminary design. Through the years, Greeley and Hansen has provided planning, design and construction engineering services that has helped the City of Tampa become one of the finest wastewater departments in the Country.

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