Thread by @emilygrubert

Managing stormwater is a huge challenge, and climate change isn't making it any easier. If you've ever been to a wastewater plant, you've probably heard about some of the bonkers challenges that excess stormwater can cause.

In today's edn of "You did what in Excel??": new tool!

Just got notification that our first paper on the cost model we built for @iDST_Team was accepted, so I wanted to do a little thread on the model.

Basic point: distributed stormwater infrastructure (like swales) can help a lot. But it's really hard to tell how much it costs.

Big issue: people can be hesitant to commit to infra like bioswales, raingardens, and porous pavements if they don't have a good idea of how it will perform.

Doubly true when 1) using public money for 2) safety-critical infrastructure that 3) replaces something they understand

"I know the pipes + wastewater treatment plant approach fails sometimes, but it works / fails in predictable ways, and no one will judge me too harshly if I do what we usually do"

[should that be true? different convo]

"I don't really know how a rain garden is going to do in my climate, my soils, my city.

And I extra don't know how much it will cost over the decades it will be in place, especially if this is the first one I'm installing."

I built the French drain for my last house myself.

I have very little recollection of how much it cost or how long it took. That's tricky bc now the next person has very little go on.

We need some way to estimate costs across v different situations.

We put together a life cycle cost tool for 16 classes of distributed stormwater control measures (SCMs), looking at grayer (e.g., above ground storage tanks) to greener (e.g., bioswales) approaches in the US.

Model and its user guide are here, paper soon:
smartech.gatech.edu/handle/1853/62…

We use a bottom up quantity estimation approach to calculate how much each SCM will cost over its whole life cycle, which means there's a cost database (high, medium, low) embedded, plus neat features like the ability to regionalize and escalate costs.

Yes! It's in Excel. Also a true model, though: estimates update when you change the assumed size of the SCM in question, there's a ton of scenario analysis built in, etc.

We also estimate and calculate monetized environmental impact -- ping if you want to discuss that decision.

Ultimately this will integrate with the full release of the @iDST_Team decision support tool, with tons of hydrologic detail and all that good stuff as well.

For now: download! Use! Really proud of this work + my student Jenna Krieger. Hope it's helpful!