The Hidden Engineering of Landfills

There's a lot that goes into them!

Of course, we have a lot of room for improvement in how we think about and manage solid waste in this world. Landfills seem like an environmental blight, but really, properly designed ones play a huge role in making sure waste products don’t end up in our soil or air or water.

Practical Engineering is a YouTube channel about infrastructure and the human-made world around us. It is hosted, written, and produced by Grady Hillhouse. We have new videos posted regularly, so please subscribe for updates. If you enjoyed the video, hit that ‘like’ button, give us a comment, or watch another of our videos!

CONNECT WITH ME
____________________________________

SPONSORSHIP INQUIRIES
____________________________________

DISCLAIMER
____________________________________
This is not engineering advice. Everything here is for informational and entertainment purposes only. Contact an engineer licensed to practice in your area if you need professional advice or services. All non-licensed clips used for fair use commentary, criticism, and educational purposes.

SPECIAL THANKS
____________________________________
This video is sponsored by Nebula.
Thanks to Los Angeles County Sanitation Districts for sharing footage and photos of Puente Hills Landfill.
Stock video and imagery provided by Getty Images and Shutterstock.
Tonic and Energy by Elexive is licensed under a Creative Commons Attribution License
Video by Grady Hillhouse
Edited by Wesley Crump
Produced by Ralph Crewe
Graphics by Nebula Studios

[MadNitr]

im a heavy equipment mechanic at a local landfill and this is the most comprehensive explanation of the inner workings of a land fill I've ever seen *standing ovation*

[Joeyzoom]

All those times as a kid that my parents said my room "looked like a dump" were secretly compliments for my curiosity of engineering. Fascinating 💪

[wahkaman]

My 6 year old son sat down to watch this video with me and was mesmerized. He has now been requesting your channel daily. Thank you for presenting these concepts so well. Couldn't be happier to turn this on for him.

[holylandfan]

I always thank the trash truck man & dept, every time I can. Their job may seem degrading to some, but theirs is the most important. You’d notice their absence quickly.

[dancledan]

"I have a scale model of a landfill in my garage"
Me: Me, too! ...Oh... that's what he meant.

[chrisgotski]

I've been a Garbageman for 22 years, and I personally pick up 30 tons of trash a day. People would be surprised how much waste we as Americans throw out daily. I think it's gotten worse with the poor quality of things we buy. Things just don't last as long these days. I always pay more for Quality so I don't have to add to this problem.

[tfrowlett]

I live near a landfill, most of the time you don’t notice much, but when it rains you can smell an acrid aroma depending on which way the wind blows. I’ve often salvaged a lot of interesting things, mostly tools or machine parts. The landfill collects the methane produced by the waste and uses it to generate electricity for the site. The sad thing is the road leading to the landfill (which is a major highway) is constantly littered with trash, mainly from trucks but also from illegal dumping.

[RobertChurch-cu]

I was involved in the siting, design, and construction of landfills for 35 years as an engineer. This is one of the best non technical descriptions I have seen. Thank you

[CB-sree]

My dad passed away almost 15 years ago. He owned a hazardous waste company and one day when we went to the dump he gave me this very interesting in depth overview of how it all worked. The first few times you said “garbage juice” I was like “but there’s a name for that…what is it?” Thanks for sneaking “leachate” in there. What a funny topic to make me think of my dad and our nerdy conversations today. Thank you for this. ❤

[tomatoanus]

I used to be a GCCS engineer (gas collection and control systems). I designed the “pipe system” inside landfills that led to and from the wells. They’re only briefly mentioned in this video but they’re critical to a landfill’s maintenance through their whole life! Some interesting things is that as a landfill is filled, naturally the weight pressing down on piping increases. We want to avoid a pinch in lines running to wells since that would lead to a pressure buildup and no suction at the well. Because of this, the pipe systems were cut and abandoned in place every >20’ of fill on top. We would often have to extend wells as well to reach the surface when there was fill on them. The pipes also need to run at a minimum grade (angle) to ensure any condensation flows downhill to a sump! If there are valleys, the condensation will pool and create another blockage. Super interesting stuff!

[pilotpear]

One of the most fascinating things about landfills, that was briefly touched in here but goes much deeper, is that the internal chemistry has an entire lifecycle that has been very thoroughly studied and modeled. You can actually predict the volume and composition of leachate and gas discharge to astonishing accuracy based on just the size and what phase of "life" the landfill is in. It even informs things like what can be placed together and what has to be segregated into seperate cells, for example construction/demolition waste and food waste have to be kept as far apart as possible because the gypsum in building waste acts as a rich sulphur source that the microbes in food waste will convert to hydrogen sulphide, at certain life phases of the landfill, which is an odour hazard but more importantly is extremely toxic when concentrations get higher, like in the case of combined food-building waste!. I can honestly say, after studying landfill chemistry, I see them as essentially giant bioreactors for processing waste, rather than a static graveyard of trash.

[LucasGarcez-qu]

My father is a sanitary engineer and worked a lot with landfills. I grew up listening to him explaining how complex and actually how amazing they are. Cool video! Reminds me of good times with my father!

[ocko]

Thank you for covering landfills and solid waste management!

Some other current issues facing landfills include (that could be followed up in another video): PFOS, hydrogen sulfide, "black goo" (largely from diapers), lithium batteries, deep-well leachate injections, siting of new landfills vs. changing consumer disposal habits.

Also there has been more investigation of resource reclamation of buried waste. Think mining of landfills.

Lastly, having been a geotechnical engineer in the solid waste industry, this video just scratches the surface of the mountain of engineering that goes into landifll permitting, design, construction and operation.

[jamesvanantwerp]

My hometown (in Kent County, MI), had only 2 years of life left on its landfill. So they built a comprehensive waste sorting facility, where municipal waste could be sorted into combustible and recyclable waste. By burning much of the waste before it was landfilled, the county is able to generate power and increased the lifespan of the landfill to 20 years, since now it just takes in ash.

[lebowski]

I’m a landfill design / CQA Engineer, and this guy has bloody nailed it! Appreciate the content mate 👍

[Loxie]

I am a Leachate tech and worked in the industry for 15+ years. Nice simple video to explain this type of landfill. You should have a look at hydraulically contained landfills, by far the safest type and the most interesting. Also not mentioned but a real problem in landfill is fires, and how we fight them is really cool.

[TTVToxic-yuov]

I'm a truck driver and can't say enough how much I love this channel!! Driving through, over, under, and around infrastructure every day and because of this channel I understand more and more. I love it

[tacticalguy]

I'm a Regional Manager for a company that designs and operates Renewable Gas plants. We specialize in landfill to natural gas and landfill to energy facilities. The amount of engineers and thought that goes into a trash mountain is crazy. This is a great video that goes over the inner workings of a landfill. I'd love the chance to run you through the system of scrubbing the raw gas from the landfill to heat homes and such. At a plant in NC, we also use a "virtual pipeline". AKA we truck the processed gas to a utility pipeline.

[nunbub]

I'm a civil engineer that has worked with dozens of landfills. This is a fantastic explanation of landfill construction, operations, and maintenance. Well done and you earned a subscription from me!

[clarkfluegel]

In Michigan, a retired landfill near me was turned into a park, including a full disc golf course... I believe there are others that were turned into snow sking hills.