Hot Sludge Sundays and Landfill LeachAde

09 Jul

Mmm, mmm good.

I hosted a group of high school science teachers and some sustainability interns on a garbage and recycling learning journey yesterday. It was great, and exhausting for some reason. We hit a high school lunch room, the hazardous waste facility, Millennium Recycling, a couple of green buildings downtown (this one and that one), and the big ugly Landfill. We also toured the City of Sioux Falls’ Wastewater Treatment Facility, where we learned what’s green in the sewage business, and were introduced to a little taste of heaven: “Hot Sludge.”

The Hot Sludge Lake Boat.

The Hot Sludge Lake Boat.

After the little micro-organisms eat up the poo and other nasties in an anaerobic digester, the remaining “solids” (which the dudes at the wastewater plant affectionately call hot sludge) get pumped over to Hot Sludge Lake–a settling pool. On this yummy lake is a boat, which operates a dredge that stirs up the hot sludge (which by this time is now just your average warm and soupy sludge) and scrapes some off the bottom to be turned into SiouxperGrow. Yes, the sludge eventually becomes a brand-named fertilizer for Minnehaha County corn and soybean fields. It’s injected by a fleet of honey wagons. Oh, one more thing: not only is there a guy who’s job it is to drive the Hot Sludge lake boat, but they also have to do maintenance on that sucker. Underneath the boat. While it’s still floating on Hot Sludge Lake…

And at  the landfill–which I learned is not a hole at all, but a gigantic mountain of compacted, decomposing garbage and earth that rises from the prairie at an alarming rate–we were shown the “Leachite Pond” (which for quite a few minutes, our group thought was called the “Leachade pond”). This is the holding pool for the “solids” left over from a literal mountain of decomposing garbage. The hot sludge of the landfill, if you will. It’s one of two byproducts (other than the mountain). The other is methane gas, which the Sioux Falls Sanitary Landfill is now piping to a nearby Poet ethanol plant to be used to make corn fuel.

Beautiful compost in the making.

Beautiful compost in the making.

The pipeline thing is pretty cool, and of course I was fascinated by the stretching piles of composting grass and leaves (get yourself some free compost–all you can scoop). But overall, the Landfill sucked all the energy out of me.  Witnessing rolling cornfields and precious wetlands in the process of becoming a giant garbage mound the size of Madison is tough stuff for me. Imagine this: you take the valley that Montrosians call home, and you fill it to the top with layers of garbage and dirt. Then you continue building up a mound that buries the water tower on the hilltop. Do that from the ballpark north of town to the south end of the Horstman Addition out by I-90. Now you’re mental visual is close to the real thing.  At least our tour guide Pearl was shining with hope and enthusiasm.

There are a couple of new “cells” ready to be filled up and mounded, with plans for up to five more on the land the Landfill already owns. These cells are about the size of Montrose, and take 5-7 years to fill up, based on the current five-county population the Landfill serves (which is estimated to more than double in the next 20 years).

We are wasteful creatures. But hey, we’re really getting good at helping nature make hot sludge and leachade.


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One response to “Hot Sludge Sundays and Landfill LeachAde

  1. Nathan Schock

    July 9, 2009 at 9:03 pm

    Wow! Who knew there was so much to learn about garbage?


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