A lesson about the way sludge works in a landfill was brought before the County Commission in a special work session to cap off the month of July, this time with a focus on how the byproduct of wastewater treatment is impacting the Grady Road facility.

County officials sought out their expert witness and consultant Kent McCormick to help provide information.

McCormick admitted right off that he knew some about sludge with his experience over the years in landfill operations, but he knew someone that would be able to help explain it all better than he.

His former business partner Wes Hulsey of Hulsey, McCormick and Wallace was brought in to provide a presentation on the interaction of various sludge and landfills, and give commissioners the opportunity to ask questions to help better understand this specific side of operations at the Grady Road Landfill.

The short answer is the experts think the small percentage of sludge buried with the trash over the past five years is only a small portion of the overall amount within. But the issue as a whole is more complicated than that, and requires some explanation on the differences between sludge that went into the landfill prior to the injunction put in place in the opening rounds of the lawsuit between Polk County and ETC of Georgia, a subsidiary of Waste Industries.

Hulsey — who started in wastewater treatment at an early age in a family pumping business — now spends his days helping municipal and industrial customers design, permit and implement treatment plants across the southeast.

“After this presentation, more about wastewater treatment and sludge than 99 percent of people,” he told commissioners before he delved into the topic of the night.

He started by pointing out that technically, sludge isn’t what people think it is at all. Most sludge that is generated happens right in the backyards of people living in Polk County who have their toilets within tied to a septic system, which generates it as a byproduct of breaking down wastewater.

Others have it in the form of aerated lagoons, which pump wastewater into a central point and break it down in an open pond full of the same kind of bacteria used in a septic system, writ larger with water pumped to keep the flow moving and break down materials faster.

The most common kind of sludge people generate — the stuff mostly buried within the Grady Road Landfill — is created from municipal wastewater systems breaking down materials within the sewer system to put back out as clean water into tributaries across the country.

Hulsey let videos from the Rural Community Assistance Partnership (RCAP) explain the basics of wastewater treatment from the time a plant receives the water, to the time the sludge ends up in a place like the landfill. Basically, water comes into a wastewater treatment plant and goes through a series of processes and tanks — screens, breakdown in holding tanks and processed with microbes that break down waste while moving water all the while — that when completed comes out as the dead bacteria that is dried as much as possible and then disposed of as solid waste.

That sludge is mostly the remains of dead bacteria, with only about 20 to 30% of the water squeezed out through various processes at a wastewater treatment plant which then in past years was trucked out to a farm field and spread out as fertilizer. That practice was also only done for non-human food crops, like hay or pine tree farms.

Other manure sludge — say chicken litter — has traditionally been used this way as well.

Then there’s the other side of sludge, the stuff created in food and manufacturing process. Industrial sludge that in most cases is pre-treated at factories across the country before ending up in places like the Grady Road Landfill.

One of the rules is that sludge has to be disposed in lined municipal solid waste landfill if not land applied in an agricultural setting. Utilities that have inadequate sludge treatment, or lower levels of treatment that don’t have adequate processes also end up in landfills as well, Hulsey explained.

Hulsey went into additional detail about one particular type of sludge that no one wants to take: grease, fats and oils. It is hard to process, it smells to high heaven and is also difficult to handle overall. In a scale of 1 to 10, with 10 being the highest, the grease, fats and oils generated through cooking processes sit at a 10.

By comparison, municipal wastewater sludge sits at about a 5 on that scale with what was going into the landfill locally prior to the order from Grubbs curtailing some of the operations. Class A, the sludge generated from plants in places like metro Atlanta, Chattanooga and larger cities sit at a 3 on the scale.

Previously, the municipal wastewater sludge would have been applied to farm land, thanks to 1993 regulations promoting the use of sludge as a fertilizer for non-human crops. There were problematic outcomes from the practice, for one the increasing spread of the urban into the rural and thus decreasing the amount of available close land to use farm distribution.

Utilizing on-hand manures like chicken litter in rural areas for grazing and hay land makes more sense than to spend additional money trucking in sludge from metro areas, which because of the water weight costs more the additional mileage. Other problems like odors and pests, accumulation of metals in the soil over time, public perception have curtailed some of the practice as well.

So in response, sludge began being buried in landfills instead because the cost of dumping was lower than spreading it on farm fields.

Hulsey and McCormick both discussed some of the problems that go along with including sludge within a landfill. For one, landfills are taking in a lot more sludge than ever before which increases the amount of airspace being taken up at one time.

Grady Road Landfill isn’t one of those taking in a growing amount of coal combustion residual, or coal ash, but other municipal solid waste landfills have been. The two also talked about concerns of how because not all sludge is created equal, it can cause problems within the landfill itself and bring about a slope failure.

They specifically showed off how a landfill in Pennsylvania suffered a slope failure that spent thousands of cubic yards of material down a slope into a landfill, caused because too much coal ash went into the facility. McCormick said that became a greater concern over time if a landfill contained more than 15 percent of its airspace in sludge.

Grady Road Landfill, on the other hand, has only over the past five years used about 5% of the airspace on sludge based on the data McCormick reviewed. He said that he wasn’t immediately concerned with the sludge within the facility at this time.

”Up until the last five years, landfill use was expensive,” Hulsey said. “Back in the 90s, the counties used to be in the landfill business... the Waste Managements, the Republics and Waste Industries saw the opportunity.”

Those companies offered good bargains at the time to operate the landfills, which brought the prices down.

”Ten years ago, there was a lot of airspace and the prices dropped,” Hulsey said.

McCormick said the companies that now run landfills are in the business of selling their airspace, and that it isn’t want to consume it fast but because the volume provides more dollars to the bottom line.

”They want as compactable, as dense a material they can charge the most money for in the landfill,” Hulsey added.

They are concerned more about the sludge increasing the amount of leachate and methane gas within the landfill, which can cause breakouts of liquid and gas that can cause additional environmental problems.

”From a stability standpoint, I don’t see sludge as being a problem at your landfill. From a stability standpoint,” McCormick said.

He added that “The concern is and what we’ve been looking at — I’m really not that concerned from an enviornmental standpoint. We’ve been trying to identify areas of concern is for odors... (we were trying) to get a handle on odors and you know, that seemed to be a potential smoking gun.”

With the temporary injunction in place from Judge Grubbs’ order keeping sludge out of the landfill and requiring daily cover, no immediate action was needed in regulation of sludge at the landfill.

However, Hulsey and McCormick did discuss potential regulation coming down the line from the Georgia Environmental Protection Division on sludge being included in landfills.

”I know that Georgia EPD has sent out surveys over the past few years, and they are collecting data and analyzing how much sludge they will allow in a landfill,” McCormick said.