By Emily Meza, Nicholas School of the Environment ’18

The most interesting discussion I had during my group’s three-day trip to Lowndes County, Alabama, was over lunch. One interested resident- who I’ll refer to as J.S.- was curious as to what brought our unlikely group to such an out of the way location. We stuck out as a mixture of 5 local volunteers and 8 students and professors from Duke.  After a bit of cajoling, he got it out of us that we were in Lowndes to study the “lack of access to wastewater infrastructure,” or more simply, the failing septic systems that have gotten many residents in trouble with the health department. J.S. had much to say on that subject.

In Lowndes County, Alabama, traditional septic systems with a simple leach field just don’t work. The soil is clay-based and the water table is high, giving the effluent nowhere to drain.

It turns out J.S. had recently installed his own version of a septic system with a raised bed at his parent’s house. The needed capacity was small, only two adults. But their house was going to be condemned, so he started digging and installed a system that he priced out around $2,300. Of course, this wasn’t an “engineered system” – there was no stamp by a professional – so his improvement is not to Alabama health code standards. However, according to J.S. it has stopped wastewater from backing up into his parent’s yard, alleviating the problem.

J.S.’s understanding of what needed to go into the system to make it work was quite sophisticated. I handed over my notebook so he could sketch what he was explaining to us. His design used sloped sand and gravel bed for drainage, complete with overflow ditch.

His hypothesis is that it is all about heat and oxygen– the water isn’t percolating down; it is evaporating up. The gravel absorbs heat over the day, getting quite hot, helping effluent steam off. The size of the gravel is also key – you need to use # 57 gravel. Peat gravel wouldn’t work because it gets clogged. The coarser # 57 allows for air pockets.

After hearing the specificity of the #57 gravel, I asked J.S. what the slope of the bed – 10 degrees? 15 degrees? His response was that he didn’t know fancy things like degrees. But he did. I asked him to draw it, and he could. All that need to happen then was to translate what he drew.

I don’t have the engineering background to know if J.S.’s explanation is how the system truly performs. To some extent it doesn’t matter if the water evaporates up or has time to percolate down through the sand, since it works. My personal guess is that it is probably a bit of both.

My conversation with J.S. showed me that there is deep local knowledge of local problems. As an architect, my job was to translate from the engineers to the clients and back. In Lowndes, the people living with the problem aren’t at the table with the engineers. As the larger Duke –ACRE partnership continues, I hope local citizens will have a chance to team up with engineers to share their lived knowledge.