Cobb County Government

Washing the waters clean

Above, Lead Operator Mike Roper describes the workings of an aeration basin at the Northwest Water Reclamation Facility. On average, the treatment plant processes 6 million gallons of sewage a day. Below right, Operator Avinash Shah tests a water sample to ensure it meets quality standards. Below left, Maintenance Technician Mike Seabrook conducts preventative maintenance on equipment. (Photos by Gary A. Witte)

By Gary A. Witte
CobbLine Staff

The flow never stops.

On an average day, it might be more than 6 million gallons. On a busy day it can reach up to 12 million gallons. And the Northwest Water Reclamation Facility where this flow goes is the smallest treatment plant of the four in Cobb County.

Cobb County employees work there on 12-hour shifts, every hour of the day, every day of the year.

And the sewage just keeps coming in.

“We have to have coverage all the time,” Northwest Superintendant Bob Herbick said. “Weekends. Holidays. It doesn’t matter.alt

There are millions of dollars in technology and endless hours of work involved in transforming wastewater into clean water.

Dozens of pumps. Dozens of motors. Electrical systems and backups for the electrical systems to run them. Storage basins to hold the wastewater during each stage of the treatment process. Biological containment tanks. Disinfectant systems.

Staff members constantly monitor the equipment, the endless process and the water itself to ensure it gets properly decontaminated. They use preventative maintenance checks on the machines and chemical lab analysis for the water.

“It takes us working as a team for this place to work,” said Maintenance Technician Mike Seabrook, who has spent 27 years performing his job with Cobb County. “It goes hand in hand.”

Once the water is rendered safe, although nonpotable, most of it is pumped into Lake Allatoona. Because the water is sent to a lake, Environmental Protection Division requirements are extremely stringent, Herbick said.

“It has to be very clean,” he said.

The plant itself sits on a 95-acre plot of land off Old U.S. Highway 41 surrounded by trees, which in turn are surrounded by a public park, private homes and businesses. The sewage comes from Northwest Cobb, Acworth, West Kennesaw, and portions of Cherokee and Bartow Counties areas.

Despite the volume of waste that comes through, there are few places in the facility where it smells like what you think a treatment plant would smell like. Throughout the plant are sprayers to help neutralize offensive scents.

“We’re dead in the middle of a community here,” Lead Operator Mike Roper said. “We try to really stay up on our odor control.”

Wastewater treatment begins almost immediately. Metal bar screens and a series of four chambers help remove large items from the sewage, such as rags, trash and even dead animals. These items are compressed and sent to the landfill.

From there, the wastewater is kept in four different equalization basins, each capable of holding a million gallons. For the system to function, the water has to flow, so some is stored to run through during the night.

The circular pools of the primary clarifiers are next, where solids sink to the bottom and grease rises to the top. Lime is added to adjust the alkalinity and get rid of the ammonia.

Then the sewage is pumped to the aeration basin where microorganisms and air are added to help clean the water further. The basins resemble large swimming pools, except the frothing brown water poses a greater hazard that one might thinaltk.

“A lot of the volume in this tank is actually air,” Roper said.

Because of this, a person who falls in wouldn’t float. They would immediately sink to the bottom about 20 feet below the surface, he said. Roper cited a past case in another metro county where a worker died after falling into an aeration basin.

Roper said the workers take these risks seriously. They participate in monthly discussions and training led by the Water System’s safety officer to prevent such accidents.

“We’ve got a very good safety program with the county,” Roper said.

After the water is sent through secondary clarifying pools, the resulting biosolids are sent to the dewatering building. These materials are pressed, compacted and then dropped by a conveyor belt into the covered metal dumpster on the back of a huge truck.

The trucks, which can carry 16 tons each, take the biosolids to be buried at the landfill.

“Our average is three truckloads a day” Superintendant Bob Herbick said.

The water is then filtered through sand and treated with ultraviolet light to kill remaining germs. Lead Operator Mike Roper demonstrated the result by pouring a cup of the now-clear liquid into his hand. There’s no evidence of what it once was. It’s then sent on its way back to Lake Allatoona where it helps maintain flows in the Etowah River ecosystem.

“It’s one of those things people take for granted,” Roper said. “People flush the toilet and forget about it.”