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Another week, another A2CA session, this time, at Ann Arbor's Wastewater Treatment plant.

If you ask Google Maps for transit directions there, it tells you to take the 3 to Geddes and Dixboro, walk along Geddes to Parker Mill County Park, then walk south through the park to the plant.

So, that's what I did. The walk through the park, alongside Fleming Creek, was lovely. At the end of it, I could see the treatment plant--just on the other side of some fences and a railroad track.

So much for Google Maps.

So, I walked west along the path, across a bridge over the Huron River, to Old Dixboro Rd, where I thought I saw a railroad crossing. Alas, it was behind a locked gate. By this time it was getting dark, and I was getting discouraged, so I texted a fellow A2CA participant for help. That was when my phone died.

So, it was cold, and dark, I was on the wrong side of some railroad tracks, and I had no working phone (or map).

Anyway, it took a little more trial and error, but I did make it, about 20 minutes late.

I was a little miffed, after all that, that we spent the whole session in a conference room. I'll have to go back for an actual plant tour.

Earl Kenzie, the plant manager, is an affable and interesting guy. His presentation is here and includes some cool historic photographs of the plant being constructed in the 1930's, so you should go look at it now.

As it turns out, maybe my walk there did help my appreciate one of their challenges: the plant is locked in by a triangle of the active railroad, the Huron River, and Fleming Creek, which limits expansion.

When you flush the toilet, this is where it eventually ends up, after a trip through a sewer network that serves 130,000 people in the city of Ann Arbor and in Ann Arbor, Scio, and Pittsfield Townships. By the time it gets here, apparently it's basically a lot of grey water--18.4 million gallons a day of it on average, but it can go much higher during storms, and part of the plant is taken up by a huge system that can hold the surge when the plant temporarily can't keep up. Treated liquids are eventually released back into the Huron River, and solids go to either landfill or farm fields (where, for fear of contamination, they can only be used for crops like animal feed which don't go directly to humans).

Our sewer system is entirely separate from our storm water system--the latter is what handles water, for example, collected from storm drains in our roads. But during a big storm some storm water still can make it into the sewer system.

The annual budget is 15 million, which I believe is mainly from user fees. The city is required to base utility fees on costs (it can't use them as a way to raise general fund revenue), and to charge by use, as best it can. But of course our houses don't have sewage meters. So, if you've seen a bill, you probably know that your wastewater charges are based on your water meter--what comes in is a good approximation to what goes out.

We also heard from the Systems Planning and Engineering departments (roads!). That'll have to wait for another day....