Cabot Wastewater Treatment Plant

Location: Cabot, Ark.

Client: City of Cabot, Ark.

Completion Date: Design: May 2007; Construction: December 2008 (est.)

Burns & McDonnell, performing as a subconsultant to USI-Arkansas, is designing significant improvements to the City of Cabot, Ark., wastewater treatment facilities. The existing treatment plant consists of a single bar screen, a Biolac biological treatment system installed in an earthen aeration basin, chlorine disinfection and an anaerobic sludge storage lagoon.

The system was designed for an average flow of 1.8 million gallons per day (MGD), but currently experiences average flows near 2.5 MGD. In addition, mechanical problems, structural deficiencies and hydraulic problems have prevented a normal expansion of the plant to accommodate larger flows.

  • Facility plan
  • Sludge disposal study
  • Conceptual design
  • Final design
  • Construction services

Because construction of new structures is severely limited due to a lack of land, additional construction space is to be reclaimed from a portion of the adjacent sludge storage basin. Detailed geotechnical investigations are being performed to determine the best method of reclaiming the area and establishing an appropriate engineered fill.

Stored sludge to be displaced by engineered fill will be disposed of based on the recommendations of a sludge disposal study as part of the current contract, which will include a present worth analysis of several disposal options, including land disposal of liquid sludge, dewatering on-site and land disposal, and direct landfill disposal of dewatered sludge.

New wastewater treatment facilities will include a new influent pump station with submersible pumps, a pair of fine screens, an oxidation ditch capable of nitrogen removal, two final clarifiers with rapid sludge removal, and an ultraviolet disinfection system. The new facilities will be designed to treat an average flow of 6 MGD and a peak flow of 16.4 MGD. Peak flows beyond 16.4 MGD will be diverted into the existing peak flow basin.

Burns & McDonnell is designing the architectural, electrical and mechanical engineering portions for the entire facility, and also performing the structural and process design for the headworks and biological treatment system. Additional studies for future management of wastewater sludge are to be included in the conceptual design, with final design and construction of these facilities to be performed at a later date.