Shutting Down Inflow

Georgia utility finds a watertight manhole solution that puts an end to chronic SSO problems

Shutting Down Inflow

Heavy equipment operators Jonas Tobler (left) and Jerry Jones remove one of the new watertight manhole covers from Composite Access Products. Fulton county replaced 19 old manholes in Azalea Park to eliminate inflow and infiltration. (Photography by Kaylinn Gilstrap)

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In early May, Fulton County (Georgia) Public Works had its first true test.

A storm hit the area, producing 6 inches of rain over the course of a couple days — the type of rain event that for years consistently caused sanitary sewer overflow problems for the utility. But this time was different. In the storm’s aftermath, the utility had zero SSOs to report and deal with.

“It was the first time in the history of the county that we had no reported spills,” says Roy Barnes, deputy director of sewer and wastewater treatment operations for the utility. “Normally when we have rain events of 3 to 4 inches or more, we typically have a lot of SSOs.”

The secret to Fulton County’s sudden turnaround is fairly straightforward: a manhole rehab program using a combination of fiberglass inserts and composite rings and covers that create a watertight seal, eliminating inflow that was at the root of the SSO issues.

“We’ve had really good success with it,” Barnes says.

Searching for a solution

Fulton County Public Works covers a 285-square-mile area and serves 86,500 customers among North and South Fulton and Sandy Springs in North Central Georgia near Atlanta. The collections system consists of five treatment plants, 2,300 miles of pipe, 45 lift stations and about 70,000 manholes. The system already handles 51 mgd on average, so the extra inflow produced during heavy rainstorms frequently overwhelmed the system.

Barnes arrived at Fulton County Public Works in 2018, and the chronic problem of SSOs after those heavy rains immediately stuck out to him as something that needed to be addressed.

“It’s very disturbing to the citizens when you have a lot of SSOs, and then you have to go through the whole cleaning and notification process, the standard SSO procedures. I said, ‘We have to fix this,’” recalls Barnes.

Prior to that, Fulton County’s attempt at a solution, knowing that inflow during large rain events was the primary issue, had been to raise problem manholes so that they would not become submerged. Barnes instead focused on sealing the manholes so they wouldn’t allow inflow into the system, even when submerged.

“We had a bad inflow problem because the standard, iron manholes are not watertight,” Barnes says.

In doing his research, Barnes came across composite manhole rings and covers from Composite Access Products.

“I saw this product and it was sitting in a tank full of water and underneath the tank it was dry. It had been sitting in there for two weeks or something to that effect,” Barnes says. “When I saw that, I said, ‘That’s what we need.’ So we bought some and started to implement them into our system.”

Chad Nunnery, president of CAP, explains how his product works.

“The CAP composite manhole cover and frame make a more tightly mated assembly because composites remove the corrosion that fuses cover to frame,” he says. “Also, because the compression-molded composites have one mold for every cover and frame, the CAP system eliminates the higher part-to-part variation inherent in a different sand cast for each iron cover and each frame.”

To pair with the composite rings and covers, Fulton County also started approaching full rehabs of manholes in a different way. After seeing fiberglass inserts at a trade show, Barnes started having utility crews use them on manholes that required more than just the ring and cover upgrade.

“You slide them into a manhole and you rehab the manhole instantly,” Barnes says.

Crews then use a high-performance epoxy foam to fill in the annular space.

“We combined these solutions, and after we’re done, we now have a rehabbed manhole that can be submerged without any water getting into the system,” says Barnes.

A critical test

Since launching the new manhole rehab methodology a year and a half ago, Fulton County has tackled about 200 manholes, prioritizing those located near waterways and in low-lying areas.

One of the biggest problem areas in the past had been a riverside park along the Chattahoochee River that contained 19 manholes, all of which would allow considerable inflow during heavy rain when a dam upstream released water and the river would breach its banks.

“The manholes were in fairly good shape, so all we did was replace the rings and covers with the watertight options,” Barnes says. “Normally during large rain events, it was almost like clockwork. Those were 19 manholes we consistently had SSOs coming out of.”

That was why the heavy rain in early May proved to be a good test. It was the first rain event of that magnitude to occur after that park area along the Chattahoochee River had been completed.

“Typically that would’ve resulted in large sewer spill in that area,” Barnes says. “But we had zero spills. Back in 2019, we had a lot of rain, and unfortunately in that area we had a spill around 30 million gallons. It was every year. That area just gets inundated with river water and causes a lot of spills. But since making the manholes watertight, that has stopped. And it reduces the amount of flow going to our wastewater treatment plants, which helps the process.”

Growing the program

Fulton County has already made good progress with its new manhole rehab program, but there is still plenty of work left to do. There are 70,000 manholes in the system and Barnes estimates that about 30% of them are located in low-lying areas or near waterways. He’s had the utility’s GIS department help identify those priority manholes, and the GIS department’s efforts have been paired with data provided by Fulton County’s flow monitoring crew.

“They’re able to say which lines fill up first or the fastest or have an increase in flow after we have major rain events. That gives us an idea of which lines are suffering from I&I and which manholes to check,” Barnes says.

Fulton County’s system is separated into different sewer basins, and at the moment, the utility is taking the manhole work basin by basin, not maintaining any specific schedule. Street manholes will get the same treatment in time, but first Fulton County is prioritizing carefully.

“Our system is a pretty good size. We’re the largest county in Georgia,” Barnes says. “So we’re identifying all the low-hanging fruit. The areas that we know get submerged when we have heavy rains and addressing all those first.”

Spreading the word

Fulton County is using its success story to try to help educate other utilities that may be experiencing similar I&I issues.

Barnes along with Nunnery filmed a segment for Viewpoint, a show hosted by actor Dennis Quaid that airs on PBS, focusing specifically on the 19 manholes in the park alongside the Chattahoochee River that had been so problematic in the past — the most successful application of the new manhole rehab method Fulton County has had to date. Barnes says the plan is to also do a formal presentation about the utility’s work at the Water Environment Federation’s Technical Exposition and Conference in the future.

“What we’ve learned is you definitely need to address the low-hanging fruit, the known areas of I&I. That’s kind of common sense, but it’s important. If you interview your frontline staff, they’ll show you the problem areas,” Barnes says. “If you do have flow monitoring, look at the data. Try to address the areas where you know there is a lot of inflow.”

And from there, CAP’s composite rings and covers have Barnes’ endorsement as a solution to putting an end to that inflow, the cause of so many problems like chronic SSOs. His crews like them too.

“They’re much lighter, they’re easier to work with, and they do what they are supposed to do. They keep the water out,” Barnes says. 


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