The $138-million Johns Creek Environmental Campus on the Chattahoochee River in Roswell, Ga., employs membrane-bioreactor technology to treat wastewater to levels suitable for reuse water distribution.

Photo Courtesy Archer Western Contractors

Archer Western Contractors built the 15-million-gallon-per-day, completely enclosed plant, which features architectural elements giving it the appearance of a historic mill complex. The design addressed the typical opposition to a wastewater plant being built in the community. The site includes a new shared-use park and interpretive natural trail system, including a covered bridge, cascading stream and pond.

The design-build team, which included The Architecture Group, Long Engineering and Brown & Caldwell, designed, permitted, built and completed a 120-day commissioning period within 40 months, starting the project in July 2006 and completing it in November 2009.

Brown and Caldwell and Archer Western worked together so that construction methods that accelerated the schedule could be incorporated into the design. Precast beams, columns and “IDecks” were used in lieu of cast-in-place concrete for the most of the buildings.

The new facility uses green, low-impact design elements and incorporates sophisticated technologies to eliminate noise and odor issues. All equipment is housed indoors, and sound enclosures were installed around the majority of the equipment. Air intake and exhaust plenums, acoustical louvers, sound-attenuation block, high-performance windows and concrete and brick construction helped meet the county’s noise requirement. Tankage is covered and provided with odor control that treats any air that comes in contact with the wastewater or sludge.

The biological treatment process design, with swing tanks, gives maximum flexibility to the operations staff. In addition, the facility can be operated in two different modes.

The first uses biological nutrient removal with acetic acid addition as a carbon source for denitrification, producing less sludge and requiring less caustic addition. The second operating mode uses chemical phosphorus removal, in which ferric chloride is added for chemical precipitation.

Flexibility also is in place to allow ferric chloride to be used as a polishing step for biological treatment, if desired.

The plant effluent discharges into the Chattahoochee River and is now the largest membrane bioreactor plant in operation in the United States. Since beginning operations in July 2009, the facility has produced effluent that is of significantly better quality than the stringent contractual requirements.

In addition, an educational facility with a lecture hall, classroom and teaching lab will help educate local schoolchildren about the impact of water quality on the local environment.

Key Players

Owner: Fulton County, Ga. - Department of Public Works
Contractor: Archer Western Contractors
Architects: The Architecture Group
Engineers: Long Engineering, Brown & Caldwell