TAI updated the City of Harvard’s Facility Plan, which was last updated in 2005. At that time growth projections for the City were robust, largely because of the new Motorola facility constructed in the late 1990’s on the north side of town. Motorola has since vacated the property, and as a result growth has been stagnant. The previous projections for growth became obsolete and the facility plan needed to be updated to reflect more realistic expectations for the future. Additionally, Harvard’s wastewater treatment plant is aging and much of the equipment is in need of repair or replacement. A phased implementation plan was needed to keep the facility functioning efficiently. Finally, Harvard’s anticipates that ammonia-nitrogen and phosphorus effluent limits will become more stringent in the future. All of these factors led to the City requesting that TAI update it facility plan.
The existing treatment facility includes influent screening, grit removal, primary clarification, attached growth biological treatment using rotating biological contactors and a packed tower, chemical phosphorus removal, final clarification, and chlorine disinfection. Primary sludge is anaerobically digested and the waste activated sludge is digested aerobically. Sludge dewatering is accomplished on drying beds. A large excess flow storage lagoon is located across Route 173 from the plant site.
The facility planning efforts included a conditions assessment of the entire Harvard collection system, each of its lift stations, and a process by process evaluation of the wastewater treatment facility. Several alternatives were evaluated to meet the City’s current and future wastewater treatment needs, including de-rating of the plant, reclamation and reuse (slow rate land application), a new activated sludge treatment plant (oxidation ditch), or a 5-stage biological nutrient removal Bardenpho process. The construction of a new oxidation ditch was found to be the preferred, cost-effective alternative.