Geneva’s aging sanitary sewer system could use $12.33M upgrade

GENEVA – Geneva’s aging sanitary sewer system would need a $12.33 million upgrade in order to address ongoing storm water infiltration and flooding, according to a presentation to the City Council this week.

The amount would cover several fiscal years through 2026 to address rehabilitating the city’s public and private collection systems and a second sewer crossing under the Fox River, the results of years-long study by Deuchler Engineering.

Deuchler engineer Christopher DeSilva said in order to address sanitary sewer overflows, one of their recommendations is to rehabilitate private lateral sewer connections – that is, the sanitary sewer connections that go from homes to the street.

“They don’t examine it unless something is wrong,” Deuchler engineer Bobby Peters said. “Typically, 15 to 20% of unwanted stormwater peak flows come from public sector and probably 30 to 40% come from the private sector.”

Because publicly owned systems are examined more frequently, problems can be identified sooner and addressed with preventive maintenance, Peters said.

Old sanitary sewer pipes are often breached by roots that block the flow and reduce the pipe capacity, DeSilva said.

“The more we can keep out of the sanitary system, the better,” DeSilva said.

When roots breach a sanitary sewer, they create openings where storm water leaks in during heavy rain events causing sewers to back up.

Also pipe seals wear out and leaks come in through there as well, DeSilva said.

“We have several … locations of the reported sanitary sewer overflows in the city,” DeSilva said.

DeSilva said he and other engineers structured how they’ve been working on Geneva’s system, starting on the outside and working their way inside – and have just started on the city’s downtown area.

Several industry standards to address these leaks include cured-in-place pipe lining that is essentially a pipe within a pipe, grouting is cheaper, but you can still have infiltration, Peters said.

Digging up sewers to replace them is costly and a last resort if the other two solutions are not feasible, Peters said.

Manholes can be rehabilitated with lid replacement, resetting the frame, grouting and using a cementitious coating, Peters said.

Geneva East

In the Geneva East area, engineers performed air pressure tests on 215 mainline public sector grouts.

The results were a 19% failure rate – which means the joints did not hold the air pressure, meaning storm water could infiltrate, Peters said.

But when they air-tested the private sector grouts within the first five feet of the connection, 143 of 145 connections failed, “a 99% failure rate,” Peters said.

“That percentage jumps out,” DeSilva said. “Not only do we have the knowledge that they’re old or not maintained, but we have a pretty big indication – specifically in that area – of what we’re dealing with.”

The length of the public sewer system in Geneva is 120 miles.

The estimated private lateral length is 120 to 175 miles, making the private connections 50 to 60% of the total, DeSilva said.

“We don’t think we can ignore the private laterals (connections) any more,” DeSilva said. “We think that they are a significant contributing source of storm water getting into the sanitary system. We think it’s worth doing a pilot test on small area … to see … if we are right and will this keep the water out.

The recommendation is to seal up public sewers, public manholes and private connections, DeSilva said.

Pilot study recommendation

The engineers recommend that a pilot study on private sewer connections be done in a small area of 100 homes by Wheeler Park just east of the Fox River.

The problem is that the area has an eight-inch pipe for its sewage to cross the river to the treatment plant.

“Whenever the storm water in these hundred houses area exceeds the capacity, it overflows into the river,” DeSilva said. “This is the most frequent area of overflows in your system.”

The area has had 11 sanitary system overflows in five years – after 83% of the public part of the system was fixed – prompting involvement by the Illinois Environmental Protection Agency, DeSilva said.

“This is a situation where we’ve already spent a fair amount of money on the public side and the problem is still there,” DeSilva said.

The recommendation is for the city to seal the leaks in the remaining 17% of the public system and the manholes, then grout or line the private connections DeSilva said.

“If it works, we’ll know,” DeSilva said.

The cost estimate is $530,000 for manhole rehabilitation, public and private sewer grouting or pipe-within-a-pipe lining.

However, Geneva Water and Wastewater Superintendent Bob Van Gyseghem said Deuchler’s estimate of $3,500 to $5,000 per house is based on whether the city could get a per-unit bid for all the work,

The city has a reimbursement program to assist homeowners who would reline their connections, but Van Gyseghem said the cost would be $7,000 to $10,000.

A single 20-inch pipe

The biggest challenge in the city’s sewer collection system is that a single 20-inch pipe – that is about 50 years old – goes under the Fox River to connect the area west of the river to the treatment plant.

In other words, about 80% of the city’s entire sanitary sewage passes through a pipe under the river that is less than two feet in diameter, DeSilva said.

“It doesn’t take an engineer to figure out that could be an issue,” DeSilva said. “There’s only one pipe. Anything ever happens to that pipe, that sewer’s got nowhere to go. … It’s just a risk in and of itself. Even if we didn’t have overflow issues, I would say it’s the single biggest flaw in the collection system’s design.”

The cost of another river crossing is estimated at $4.2 million.

Adding another sewer connection crossing the river would add safety and resiliency to the city’s system, he said.

Aldermen are to consider options and actions to take at a later date.

Deuchler cost estimates

For 2022 construction:

• Public collection system rehabilitation - $1.1 million

• New river crossing design and permitting- $400,000

• Private lateral lateral rehabilitation in pilot test area – $420,000

For 2023 construction:

• Public collection system rehabilitation- $1.1 million

• New river crossing - $4.2 million

For 2024 construction:

• Public collection system rehabilitation - $1.1 million

• Private lateral rehabilitation with hydraulic improvements in Geneva East - $1.37 million

For 2025 construction:

• Public collection system rehabilitation - $1.1 million

• Private lateral rehabilitation in Fargo area - $440,000

For 2026 construction:

• Public collection system rehabilitation - $1.1 million