Your Poop Next to Fibre Loop

David Slížek
August 2, 2022
Author: David Slížek

“They told me that it was impossible,” says Michal Najman during a demonstration of laying fibre optic lines into the sewer. It took him six years of painstaking development to prove that it is possible to bring fibre optics through the sewer pipes to the houses. On a cold February afternoon in the North Moravian town of Ludgerovice, he is now demonstratin gthe first installation at local new buildings. This method is unique in the world.

Najman runs the local operator Why did he go through the trouble of inventing a new way to connect? "We wanted to move from Wi-Fi to fibre optics. I found out that stretching overhead lines on poles is unrealistic, no mayor wants to do that. And digging up streets that have recently been repaired, for example, is not an option," he explains.

So he began looking if there was a better solution somewhere in the world. "I found out on the internet that fibre optic lines can be run through sewers. So I went to a Swiss company that had done it years ago. But they only ran cables in the main line - they connected government offices or hospitals. Any connections were then made by micro-milling - they cut the asphalt and put a protector in it," he says.

The problem is that while the main line is usually wide (pipes are 250 mm or more in diameter) and straight, the sewer hooks are narrower and they bend. They tend to have 30-, 60- or 90-degree elbows that the Swiss robot couldn't get through with the cable. "They told us that they had already put several million euros into the development of laying in the connections, but they couldn't figure it out. And that they wished us good luck," Najman laughs.

He decided to turn the Swiss dead end into a Czech novelty. "First, we made a robotic snake mechanism that could install clips in the 150 mm diameter pipe used for the connections. It could navigate the bends in the pipe," he says. "It was a turning point, I could see the path we were going to take," he adds.

But the road from prototype to live deployment was a long one. "It took six years to develop," Najman admits. During that time, he created a number of models, which he 3D printed. All the while, his company operated essentially without a boss, who, he says, could play around. And it wasn't playing cheap. "The materials for our PolyJet 3D printer alone cost half a million," Najman calculates.

‎The first prototype of the robot mechanism, printed on a 3D printer
Author: David Slížek

Robots in the pipeline

The robot prototypes
Author: David Slížek

How does it all work? The basis is a few robots that look like small train sets. One robot installs special clips at one-metre intervals in the main line, to which a protector is then attached. These are strips thatwrap around the inside wall of the pipe and have a clip attached at the top. "Here is the installation head and here is the tray from which the robot feeds the clips," Najman demonstrates.

Another robot then attaches a protector to the clips. "It has a pivoting arm in the front that it uses to prepare and align the protector. It is also equipped with an auxiliary laser to see exactly where to snap it," the inventor shows.

A robot also takes care of the connection from the main pipe to the connection leading to the house. "It is designed like a snake and is introduced into the connection manually for the time being. It is turned so that the clip is on top, and then the mechanism installs it into the pipe." On the prototype, it took about 20 minutes to install a single clamp; on the new robot model, where slow servo motors have been replaced by pneumatic controls, it takes about 10 to 15 seconds.

Najman's company uses original Swiss know-how, adapted to Czech conditions, to control the main line. However, the installation in the connections is its own invention, which the company has patented. "We have already been granted two patents and are preparing another one," says Najman.

Interest in optics

On both sides of the street in Ludgeřovice there are new family houses. Most of them don't even have a lawn yet, it's still a bit of a construction site. Residents have the option of connecting to the internet via one of several Wi-Fi providers or DSL.

"When we built a new sewage system in the village seven years ago, we tried to put protectors in the trenches because we were counting on the fact that we wanted to extend fiber optics throughout the village. However, the conditions of the subsidy at that time did not allow us to place them in the same trench," explains the local mayor Daniel Havlík.

Mayor of Ludgeřovice
Author: David Slížek

"In terms of cost, putting it in the ground means an insane amount of money completely beyond the current capabilities of the municipality. Running fibre optic lines overhead would probably be as expensive or slightly cheaper than sewers, but it's impractical," he adds. It's the perfect place for a pilot project to test the viability of the Czech idea of fibre optics in sewers.

The operator in Ludgerovice has been providing connectivity for over 10 years and experience was one of the deciding aspects when discussing the project. But the municipality still needs cover at all times, so the company put down a security deposit before the installation began, in case something serious happened, for example. "From the principal, the municipality can cover all the costs of restoration, such as digging up the original sewer and laying a new one," Najman explains.

But the company is prepared for most problems, he says. "In sewers, you always have to be able to bleed the equipment and pack it in an emergency package so you can pull it out if you need to. The alternative is an excavator, which of course is expensive and unpopular," he laughs.

The installation process
Author: David Slížek

Last August, the company installed its first sewer connection, and earlier this year it completed the first 300 meters in the mainline and connected its first customers. The connection ceremony took place on February 11, symbolically at 11:02 a.m. If the novelty proves itself in a one-year test run, it is expected to get the green light for the rest of the village. More than 5,000 inhabitants live in about 1,600 houses. Almost all of the houses are connected to the sewage system and the municipality is planning to connect another 120 houses in the part that is also covered by that system.

"There is a lot of interest in fibre optics everywhere," says the mayor, adding that the pilot project does not entail any costs for the municipality. Nor does he anticipate any problems with the maintenance of the sewage system, which is under the municipality's control. "There shouldn't be a problem with the protectors in the sewers. Fat plugs may form in the manholes, we may have to check them more often," he admits.

How to connect the house

"This is our sewer inspection robot," Najman demonstrates the equipment, which he reeled down into the main line a short time ago. "It has a professional camera that allows us to see how the installation is going. It can also use a laser to measure the so-called ovality of the pipe," he boasts.

That's because the pipes, which have tons of soil on them, don't have an ideal circular diameter. "We don't mind the deformation of the pipe; the clamp actually acts as a brace to prevent the pipe from bursting. We struggled with this in the beginning because it turned out that some pipes were not passable by the robot. We had to redesign it to fit everywhere," he recalls.

Sewer inspection robot
Author: David Slížek

What does the connection look like? The provider has its fibre route connected to the backbone in the main line at a certain point. There are then installation boxes in the manholes from which the cables run to the individual customer connections.

Unlike the plastic protector in the connection box, the one in the backbone must be stainless steel. The backbone pipe is cleaned at certain intervals with a pressurised stream of water and the protector must be able to withstand this procedure. "There are small stones in the water, for example, which could damage a standard plastic protector at a pressure of around 200 bar. That's why we use a stainless steel protector in the main line, which is more resistant. It is slightly more expensive, before the current wave of price increases I used to buy it for about 2 euros per meter. We have several suppliers, some from Europe," says Najman.

There's only one thing for the building owner to do - he has to stretch the guard from the house to the sewer manhole that runs on his property. "Our robot can work in pipes as small as 150mm in diameter, so if there's a 150mm pipe leading up to your toilet, we'll climb up next to the bowl," Najman says with a smile. But if someone has installed a 120mmreduction beyond their property line to save orders of magnitude of crowns, they'll have to dig.

Manhole on customer's property. During demonstrations, it is blocked so that the content does not flow out
Author: David Slížek

"The final installation of the connection is simple. A technician arrives in a van, pulls a fiber optic coupler into his car and welds the output of the transit fiber to the fiber that leads into the house,"Najman describes.

The tapes and clips don't interfere with anything in the pipe, he says. "They are intentionally placed at the top of the pipe. With sewers, it is generally assumed that there is no sewer traffic in the top third of the pipe and that part is for connecting the joints," he explains." At the same time, we count on a standard lifetime of 30 years for the fibre optic, then it has to be replaced." The guards and clips should last at least 50 years, more likely much longer, he adds.

15,000 for the connection

Does it all work out economically? According to Najman, yes. "The total cost of a single connection to a family house should be within CZK 15,000," he estimates. If you have a Wi-Fi customer, setting up a connection costs CZK 2 to 3 thousand, plus you have a cost of maybe CZK 15thousand for some part of the antenna that transmits to the client. But after every three or four years you have to upgrade the technology. When you compare that in the long run with the cost of fibre optics over the duct, it makes sense for the operator," Najman says.

A belt with a buckle into which the protector snaps
Autor: David Slížek

According to him, the most suitable sewer method is in municipalities where they have new sewage systems. "It can also be installed in a unified sewage system that carries both sewage and rainwater. But it must always be gravity sewer, where the minimum diameter of the line is 250 mm and the connections 150 mm, according to Czech standards. We can't get into the pressure sewer, which has a pipe diameter of 40 mm," he says.

By the way - there is another method for installing optics in the sewer, which was used in Vienna, for example. It is based on inserting a special sleeve into the pipe when renovating the sewer and pouring a layer of polymer between it and the pipe. A robot with a UV light then passes through the pipe, which hardens the layer and thus gives the sewer a new . A fibre optic protector can be added to this layer before curing. However, it is permanently bonded to the pipe, which may not be practical, for example during repairs.

Made in Czechia

"Your poop next to fibre loop" Najman repeats with a smile the slogan that Mayor Havlík coined for his project. At telecommunications conferences, he presents himself under the name WCnet. But considering the effort and cost he has invested in developing the solution, it is definitely no joke. That's why he is now thinking about how he wants to monetize his solution.

Author: David Slížek

"We have no ambition to become a network construction company. Rather, we want to train other operators how sewer installations work and let them do it themselves. Our business model is based on selling staples, renting robots and paying royalties for the use of the technology. We want to recoup our development costs," Najman says. But his company has not yet started negotiations with any interested parties, and is focusing on a pilot plant in Ludgerovice.

There were a number of moments during development when things looked bad for the project, according to Najman. "When I came to the Ludgerovice company HP Trend with the first design of our clasp, Mr Strachota, who is in charge of the development of plastic moulding tools, looked at it, smiled and said: it's terribly beautiful, but it can't be produced. I had to design it from scratch so that it could be made. Then again, the strength calculations didn't add up, so I had to do it again. And there were many more hiccups like that," he recalls.

While Najman has been ordering parts for the robots mostly from China, where he believes the delivery times are unbeatable, he is counting on the involvement of Czech manufacturers in the serial production. They should make us a chassis on which we will then be able to put different types of robots, depending on what we need."

Author: David Slížek

What else? A Czech inventor is working on speeding up and improving the installation process. "Our goal is to reduce the installation time for one section - that is, the part of the sewer between two channels - from the original two to three days, with the need for five technicians and a specialist to operate the robots, to one day, with the need for three regular technicians without a specialist," Najman says.

"For the connections, we're moving towards having a truck with a hydraulic arm that will pull a 12-metre robot into the 'trunk', launch it into the connection and, once installed, pull it out again, clean the 'snake' with pressurised water and move on. We'll put more electronics back in the main line to make the job even more efficient and not require the kind of knowledge of robot design that only I have. I've already figured out how it's all going to work," he smiles.

Link to the original article
Dmytro Kovtoniuk
Vladimir Pokorny

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