Teaching and researching disaster sanitation — and designing & building equipment for it — came out of my enduring interests as a family doctor in patient empowerment and infectious disease.

Pardon the dust on this page. It’s temporary. I am reformatting the paragraphs into blog posts to make the material easier to find.

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NET Camp, September 13, 2025

PowerPoint slides

NET Camp this year also included an Advanced Disaster Sanitation Workshop.
The goal of the Workshop is to meet the increasing need for Disaster Sanitation instruction, since more requests for classes and tabling are coming in than I can reasonably cover.
There is also a great need for producing large numbers of alternative sanitation equipment, like handwashing stations. The Workshop covered Teaching and Building.

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Portland NET, June 18 & 25, 2025

Videos of Part I and Part II

Part I PowerPoint

Part II PowerPoint

NETs asked 3 good questions:

• Is cedar – as sawdust, shavings, or chips – good for covering deposits in poo buckets?
• Will bagged, stored poop generate methane, that will be trapped in the plastic bags, and pose a fire or explosion risk?
• Is it safe to dig latrines in areas with so-called “underground streams,” where basements collect water unless they are sealed?

CEDAR

For covering poo bucket deposits?  Answer: It’s okay. Why is there a question? I have been teaching for years that cedar – sawdust, shavings, chips – is too oily to absorb moisture, so should not be used. 

However, Ian shared that he had gotten cedar sawdust from the sawmills that make cedar fence and deck boards on NE Sandy Blvd. Here, and here. There are also many sawmills around Portland that could be sources of sawdust from various wood species. 

Ian’s discovery of a source for cedar sent me digging into my archives and memories, to question how I knew that factoid. Nada. There was nothing in my notes or research archives. A faint memory of a conversation sent me to my original mentor in Disaster Sanitation, Carol McCreary of PHLUSH. Carol didn’t remember saying anything about cedar, but she couldn’t resist some quick research, and reported back that cedar is not great for making compost, because it rots so slowly. That won’t be a problem, because we are unlikely to compost human waste from buckets after a disaster.* (Latrine contents will compost, that’s how they work.) It shouldn’t matter whether cedar absorbs moisture or not, as long as it covers the poo solidly enough to prevent fly landings.

Fortunately, I know two people who have experience with wood products and human waste (There’s a sentence you don’t hear every day.)

Ole Ersson, M.D., leads Kailash Ecovillage in SE Portland, which has a working, legal, up-to-code humanure facility to support its gardens. (Ole, like me, is a retired family doctor.) Residents contribute pee and poo. Arborists regularly deliver mixed wood chips, from cedar and other species, which are used to cover and condition poo deposits. 
Ole writes that “our compost bins don’t have any trouble with it.” 

Kory Russel, Ph.D., is a professor of Architecture and Environmental Studies at University of Oregon, and has a Ph.D. in Civil and Environmental Engineering. He also works with SOIL Haiti, a program that saves lives with dignified, safe household sanitation, and is revolutionizing Haitian agriculture with humanure. Kory also founded CBSA, the Container-Based Sanitation Alliance, which advocates for these sanitation facilities in resource-poor nations. I know him because he’s on the Board of PHLUSH with me.

Kory writes that  “in a disaster situation where the poop and cover material are to be … dumped in a landfill, I see no problem with cedar.”

Does that imply that cedar should not be used in latrines as a cover material? No. Cedar does eventually rot. We will be in no hurry for latrine deposits to compost.  *In a better world, all human excreta would be composted into fertilizer. Using potable water to flush is a terrible waste of an increasingly scarce resource. Some fertilizers are also increasingly scarce resources, so replacing them with composted pee and poo would help. However, poo composting is not something to begin lightly. It takes serious microbiology chops, and the risk if you do it wrong is, well, dysentery. Pee, in contrast, is easy to use in the garden. 

METHANE

Maryellen asked if human waste can produce methane, and pose a risk of fire or explosion.

Answer: No.

Rotting organic materials produce methane and/or carbon dioxide. 

In anaerobic conditions – meaning “without air,” sealed shut from air flow, mostly methane is produced.

In aerobic conditions – meaning “with air,” open to air circulation, mostly carbon dioxide is produced. 

Composting, for example, is an aerobic process, and releases mostly carbon dioxide, not methane. However, water-immersed materials rot anaerobically, because free oxygen can’t reach the materials through the water, so more methane is released. 

This difference is used in certain livestock operations, which produce methane in anaerobic conditions for fuel, from liquid manure.

In the Poo Bucket, there will be dry materials, and air circulation, until the bucket is about two-thirds full, and the bag is closed and securely stored. The earliest deposits in the bucket will have more time to complete the aerobic drying and rotting process, releasing carbon dioxide, than the later deposits. We speak of “sealing” the bags, but they won’t be vacuum-sealed. There will be adequate air in the bags to minimize methane production.

Turning to the experts:

Kory writes that “[W]ithout water covering the feces, the methane production inside the center of the feces themselves (where anaerobic conditions are most likely to exist) it is really quite low to almost non-existent in practical terms. It is possible that if you did an amazing job sealing the bucket that some methane could build up but little to no chance it will explode the bags and/or catch fire. …. The concentrations of methane produced at the scale of a bucket or Wheelie bin or dumpster is just too small to create a real risk. Plus methane is wicked good at leaking out of storage containers.”

Ole writes that “The amounts of methane in eventually sealed bags would be very small and would not generally pose a problem of exploding a storage bag. …. In temperate conditions little methane is likely to be produced. …. Indeed, our buckets are stored in an outdoor staging area with lids on top. But they’re not sealed. The lids are only to keep rain out. At outdoor Portland temps they likely produce negligible amounts of methane.”

LATRINES over “Underground streams”?

Vicki asked about the risk of contaminating groundwater by digging latrines in areas, like her neighborhood, with “underground streams,” where basements flood if they’re not sealed tight. This is a common phenomenon on Portland’s West side. I checked the water-table map for her street; It said the water table was hundreds of feet below these flooding basements – so they shouldn’t be flooding. I also checked a section of my neighborhood, South Burlingame, where residents say there are “underground streams,” and basements flood if they aren’t sealed. The water-table topo map said the water table was hundreds of feet under those flooding basements. What’s going on? 

I found two expert sources: 

Daniel T. Snyder, M.S., the hydrologist who built the Portland water-table topographic map that tells you how far above the water table you live. He retired from the USGS Oregon Water Science Center in 2015, but he graciously answered my email with a detailed explanation. Scientists and public servants deserve enormous respect! (I hope someday, someone will have to explain to a young person why a writer would put it that way in 2025.)

Stephen B. Gingerich, Ph.D., a research hydrologist at the USGS Oregon Water Science Center, in the area of groundwater contamination.

Answer: The basic rule for digging latrines still holds, even in those neighborhoods where basements have to be sealed watertight: If you find water in the hole you dig, dig somewhere else. 

If you’re interested in why that is true, read on. I found this question fascinating, but you do you. Let’s dispose of “underground streams” first. I put the words in quotes because they do exist, but they are not the problem. Dan Snyder explains: “[T]here were a number of surface streams in SW and NW Portland that were piped and covered over …” because the city grew on top of them. Okay, done with underground streams. 

Next, we need to know that the geology, and therefore the hydrogeology, of East Portland and West Portland are very different, because of the Missoula Floods – which, as disasters go, were as dramatic and terrifying as Cascadia Subduction earthquakes. I’ll let Dan tell the story: “The Missoula Floods repeatedly inundated the Portland area with up to 400 feet of water some 15,000 years ago. They were caused by the breach of an ice dam holding a glacial lake in Montana.” The lake was full of water from melting Ice Age glaciers. 

“The ice dam would fail, [repeatedly] releasing an incredible quantity of water that washed over eastern Washington and flooded through the Columbia River Gorge to a depth of over 1,000 feet before flowing over Portland” then draining out to the Pacific along the Columbia River.

“And then, after a hundred years or so, the ice dam would re-form, and the lake would refill, and then the dam would fail again.  There is strong evidence that this occurred over 40 times.” Each flood carried silt, and left it behind over East Portland, hundreds of feet deep. Why not West Portland, too? Because West Portland was already hilly before the Missoula Floods. Since the floodwaters only rose to 400 feet, they covered what is now downtown, and stopped there. 

This is what an East Portland water table looks like:

And this is what a West Portland water table looks like:

The “Low permeability rocks” are hard lumps, made of substances that don’t let water through. They could be boulders, slabs of rock, or deposits of hard clay, that settled in the rumpled land mass that is West Portland. The slabs below the current water table are surrounded by water in soil. They only matter to a builder trying to dig through them. 

But if a low-permeability block sits above the water table – it collects water. These water deposits above the water table are called “perched water,” and they are the problem. The amounts of water they hold don’t change much: When rain falls on the ground above the slab, it percolates down through the soil until it stops at the slab. But just as a hand can hold only so many strawberries, each perch can only hold so much water. If water is added from above, some of the collected water will overflow its perch, and resume percolating down through the soil until it reaches the water table. 

Soil changes water passing through it. Soil is an active filter, in which bacteria, fungi, etc., neutralize harmful bacteria before they can reach the water table. We depend on that process when we dig a latrine in deep soil in East Portland. It works in the more complex geology of West Portland, too. Just don’t toss any chemicals in your latrine, Gingerich emphasizes. They could pass through soil intact, and contaminate the water table. 

These perched-water collections would be difficult, if not impossible, to map – like mapping the nuts in a brownie. That’s why certain basements are wet; they were inadvertently built into perched water. 

Clear? No change in instructions for digging latrines. But those of you with wet basements now know why.

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Northeast Village PDX, Oct. 10, 2024

Presentation Slides

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NET Camp 2024, Sept. 14, 2024

People had questions about sewage pumps, and whether they flood houses with sewage in a disaster or a power outage. What’s a sewage pump? It’s a pit where sewage and grey water collect, with an electric pump at the bottom that turns on when the pit reaches a certain level, to pump the sewage and grey water out to the sewer line. (Note: A sewage pump is not a sump pump.)
Sewage pumps are required for houses with bathrooms below the level of the main sewer line.
Houses above the sewer line discharge sewage by gravity.
Here’s a diagram I found:

So the answer depends on the situation, and on how full the sewage pit is at the beginning of the problem:
In a major disaster, sewage will NOT back up into the house, because there will be no incoming water to fill the toilet and add to the sewage in the pit. Sewage will be the least of your problems.
In a power outage, the pump won’t turn on. If sewage and grey water are added to the pit, without a functioning pump, the pit contents could back up into the house, or onto the ground outside.
In the January 2024 ice storm and prolonged power outage, Multnomah NET’s Team Leader, Tom Boeker, went from door to door in his low-lying, sewage-pump-equipped condominium complex, asking neighbors to minimize water use to avoid overfilling the pit. There was no sewage spill.

Presentation Slides

NET Camp 2024 Class Handout link

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Medical Reserve Corps, Regional Conference, April 14, 2024

Presentation Slides

Medical Reserve Corps Class Handout link

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The NET Fair class asked good questions:

“Where in Portland are people too close to the water table to safely dig a latrine?”
Answer: Here’s the map. Land next to bodies of water (rivers, lakes) may have a water table within reach of a shovel, including Hayden Island, the Smith & Bybee Wetlands, and the airport. And obviously, the higher the hill one lives on, the farther down the water table. The vast majority of Portland is at least 20 feet above the water table, too far to reach with a latrine.

My sanitation presentation makes assumptions about gender, as someone pointed out. Gendered anatomy does make a difference for sanitation equipment choices, but obviously not everyone equipped with either gender’s anatomy identifies with that gender.

“What’s a ‘rat-proof enclosure’?”
(Context: for storing bagged poop, to keep rats away.)
I listed roll carts, in a shed or garage reinforced with quarter-inch hardware cloth.
More ideas:
Dumpsters. Make sure the drain in the bottom is capped, and that there are no overhanging trees or nearby buildings that a rat can climb to jump onto the dumpster.
Shipping Containers.

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