The words from above came from this person's mouth.

After the Sword Cultivator came up, Xu Yun took the initiative to hand him a cigarette—Xu Yun himself doesn't smoke, but he has a habit of carrying a pack just in case:

"Sir, is there anything unusual in that pipeline?"

"Tsk, Tsk, Yuxi, thanks man."

The maintenance worker took off his gloves, grabbed the cigarette, tucked it behind his ear, and then said:

"Unusual? Nothing unusual, just that one section of the pipeline smells much less than the other areas."

Xu Yun instantly became interested:

"Smells much less?"

The maintenance worker nodded and stretched out his calloused left hand, pointing to the manhole cover:

"The pipelines under the basketball court are 1800mm in size...that is 1.8 meters, and further ahead there are some 2400mm ones and a main external one that's 3000mm."

"There's one section...oh, about under the basketball court you mentioned, where the smell is a bit weaker than the surroundings. I figured it might be because there's less accumulated garbage."

Saying this, the maintenance worker laughed:

"After all, it's a sewage pipeline. With water flowing, the amount of garbage at each point is certainly different..."

The saying goes.

He speaks unintentionally, but the listener takes it to heart.

Xu Yun is not a student in urban planning or engineering design, if he had heard this on a normal day, he might just nod and accept it vaguely.

But today is different.

Xu Yun is very clear that there must be something unusual with that basketball court area:

Either the air above it is special, or there is something underground.

Given this premise.

The maintenance worker's words that the smell is fainter in that area couldn't help but make him think deeply.

Then Xu Yun thought for a moment, turned to Guo Yuting, and asked:

"By the way, Xiaoguo, how do you conduct soil sampling?"

Guo Yuting bent down, took a form out of a backpack on the ground, and handed it to Xu Yun:

"If there's sludge inside the pipeline, we would definitely scrape the sludge. If a significant cockroach congregation phenomenon is found near the pipeline—for example, when detecting a large amount of cockroach excrement, then you can fill out this form to report it, and then have the engineering team drill down quantitatively."

"Once it's reached a certain depth, then just go and sample the soil."

"The school's support is very strong this time, after all, such specimens are indeed rare."

Xu Yun nodded knowingly, understanding the procedure of Guo Yuting and her team.

Anyone who cares about cockroaches should know.

Cockroach excrement contains a type of ester called ezoria, which can be detected with special NAC test paper.

Moreover, the higher the concentration, the faster the reaction, and it is still quite simple to detect.

Therefore, the step that Guo Yuting and her team follow is to scrape off sludge if possible, if not, use test paper instead.

Once signs of significant cockroach activity are detected, then it's time for the digger to go doo-doo-doo,

The large sewage pipeline cannot be more than 0.7 meters from the ground, and the pipes within the university usually range from 1.5 to 5 meters deep.

The largest external main pipeline is around 3 to 7 meters deep, varying depending on the university.

This depth is not very deep, usually reachable by vehicle equipped with a drill; the key is the operator's technical skills.

Although this way, the cost will definitely be higher than with pure manual digging.

But as Guo Yuting said.

In a school like Ke Da that has eradicated 99.99% of cockroaches, leaving only the main nest unhandled, it's almost a rare spectacle not seen in decades.

In the face of potential returns, what does spending some excavation cost matter?

Therefore, from the school's perspective, Ke Da's support for soil sampling is still very strong.

Then Xu Yun thought for a moment, a bit of determination flashed across his mind, and he asked Guo Yuting:

"Xiaoguo, did you guys bring protective gear today?"

"Protective gear?"

Guo Yuting was slightly taken aback, then quickly replied:

"Yes, we did...why, God Xu, do you intend to..."

Xu Yun nodded heavily:

"I'm planning to go down and have a look first. If not, then use the drill—I always feel like there's something good down there."

Guo Yuting hesitated for a moment, turned to look at her two companions, and slowly said:

"Alright then..."

The maintenance worker has already checked the internal condition of the pipeline, and the pipeline is currently in a drainage state.

Unless Ke Da was formerly known as Hogwarts, and there's a chamber under the girls' bathroom with a Snake Monster that likes to wander along the sewer, Xu Yun shouldn't have any safety issues.

Also, with Xu Yun's current influence within Ke Da, mobilizing a drill first and reporting afterward is no problem at all.

Thus, Xu Yun quickly changed into a set of protective gear.

This set of hazmat suits is custom equipment by Ke Da, very durable, and of much higher quality than what is commonly available in the market.

The head area is covered by a gas mask, capable of filtering a considerable portion of harmful gases.

There's an oxygen cylinder on the back similar in size to an insecticide can—this item is mainly equipped as a backup for special situations and might never be used even a hundred times in practice.

A simple tool kit, with items like a wrench and screwdriver, is attached at the waist.

Once everything was ready.

With a headlamp on, Xu Yun went down the manhole alone.

Paris has a well-known sewer museum, with a tunnel-like interior that has an arch shape, leaving a lot of space even for adults walking in.

The sewage system of Ke Da is somewhat similar to the German-built sewer in Jiaoao, designed as an inverted V shape, and it's one of the few universities in China with a ∧ sewer.

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