Just two days ago, Trash Talk arrived in the mail. It’s the annual publication sent out by the City detailing what we Portlanders do with all our stuff when we’re done with it. In this city, we clamor for environmental statistics: number of recycling receptacles per family, the tonnage of paper recycled per year, the amount diverted from landfill to recycling center, number of full garbage can loads per family per year. And so it goes.
Test yourself! What can you put in each receptacle? In Portland, we “commingle” our recycling into the blue bin, toss our yard debris into the green bin, carefully place all glass in the yellow bin, and pitch actual waste into the gray-brown tub. Can you spot the garbage can in the photo? (It’s NOT City Hall; though depicted in the background, City Hall is not where we toss garbage. Just our politicians.)
What’s this STELLA diagram look like? Weekly material flow from my household and property (or my neighborhood, or my business) moves into these containers (stocks, of course). Thence? Good question. Who picks up what, and where does it go?
What an interesting game to play with any age children (or adults) that can easily lead to a lesson on system dynamics and sustainability. Very small children can certainly place a boundary around the garbage that emanates from their own house (They likely have to take some of it out!). Where it goes after that really enters upon the territory of older children – and the stamina of the teacher . . . that is, just how broad a boundary is one willing to draw?
Flows entering these four stocks seem readily drawn and properly labeled. As for the flows leaving the stock, well, we’re in for fun and games here. Now, we have to start talking about time frames and rates. If we collect weekly, do we measure the rate of outflow with the same rate? Where do these outflows go? Does not each of these flows lead into differing systems? Most teachers might recognize that we have four teams or four topics or four panels (depending in the teacher’s bent) that correspond to the four differing cycles of paper, metal, and glass recycling; glass recycling; yard debris recycling; and irreducible garbage. Where might this assignment lead?
Perhaps to the local landfill. Riverbend Landfill and Recycling Center is about three miles southwest of McMinnville (about an hour roughly west of Portland) and next to the Yamhill River’s south fork, but about 40 percent of its trash comes from the Portland area. Owner Waste Management wants to expand the landfill so it can accept trash for another 20 to 30 years. OK. Here’s another stock – garbage in. Might there be any outflows?
Before De La Salle North became a Oregon Green School, the Earth Club conducted an audit of our school’s weekly trash and recycling patterns. The lunch garbage audit was a thing to behold: half a dozen students and a few adults laying out a daily dose of yuck on a tarp and then separating and weighing it. In our Urban Planning class (and in the previous year, in system dynamics course), we drew maps of our school’s recycling and garbage methods. Most students did not think about any part of the system, not even the part when each tosses something into a receptacle. But we did find it relatively easy to enumerate the stocks and flows of a simple recycling system that diverts some percentage of waste from the landfill. It was enough to foment discussion and heated, specific debate. Good stuff, that.