Recently some friends of mine posted on their blog about ripping out plants. In one of the photo’s Megan is smiling as she lovingly shoves an armful of gorgeous, blooming poppies into the curbside compost bin. At first I was thinking how sad to see the happy flowers being discarded, even though I do it all the time. But I take solace in knowing they will find their way back to the soil soon enough. It’s all just a constant cycling of minerals after all, when it really comes down to it. It occurs to me that not everyone knows just what happens to our green bins here in SF after they take it all away.
So, where do they take it? Who are “they”, anyway? One of my favorite authors, Anne Tyler, ruminates on this question in one of her books (can’t remember if it was Searching for Caleb or The Clock Winder). In her cogitations, the proverbial “they” is eight grandmothers in pink flannel nighties and bunny slippers. Makes for quite a mental picture when you put it into the context of “they put in a new stoplight yesterday.” 🙂 Just what are the grannies doing with our compost, I wonder?
Here in SF we diligently sort our leftovers into various bins – black for landfill, blue for recycle, and green for compost. Recology (formerly Sunset Scavenger) hauls it off to South SF to sort it further. (Regardless of our in-home sorting, they still have to contend with street garbage cans and such.) Recycling goes off to the recycley people, but the rest goes off to glorious Vacaville, California. Apparently, Vacaville is more exciting than I was aware, at least according to their official website. My only experience was with the trash facilities, so my POV is a bit tainted. 🙂
A couple of years ago, I had the pleasure of following the green-bin trail with a Soils Management class at CCSF. It really was a hoot to get to see where it all goes and what happens to it. It’s a remarkable story. In Vacaville it goes to Jepson Prairie Organics, where it’s all sorted again. True landfill goes into a big heap, landfill-style, and gets buried until it’s the tallest geographic feature on the horizon. Western Gulls love it, so Jepson Prairie actually has a falconer on staff to control the gull population! The green waste gets minimally sorted into food versus garden waste, since the food is wetter and takes longer to process.
When we visited them, they were a few months from starting a pilot program that changes they way they process the compost. That should have transitioned by now, but the pix below show their previous method. Really, the only major change is the type of tarp being used. The old ones were $900 each and lasted 12 uses. The new ones are $4500, but last five years.
Naturally, composting puts out tons of VOC’s (Volatile Organic Compounds.) Basically, gasses that add to Global Warming. The legal limit is 1562 tons/year, but their old method was only producing 15 tons! And these new tarps reduce that another 85%! Holy methane! Not to mention, another pilot program captures the methane and uses it provide power to EBMUD (the East Bay’s utilities district).
The method involves laying out the compost in long wind-rows, which are then covered in tarps. An enormous machine (several stories tall), churns the rows every three days and injects water into the yard waste piles or sawdust into the food waste piles. The result is that in 60 days (45 for the yard waste), they have a high-quality, OMRI-certified-organic compost ready for market. They produce about 75,000 cubic yards a year. Much is sold to organic farmers, and even more goes right to the wine industry. Some gets sold and bagged for retail.
San Francisco’s compost is not alone in this endeavor. Aside from our yard debris, Jepson Prairie also processes and combines our food with that of Oakland, Richmond, Vacaville prison, Folsom prison, UC Davis, Vallejo, and Dixon. Our tour guide said the best quality, best-sorted stuff is the prison scraps! They’ve got plenty of labor to make sure it’s all properly sorted. 😉
They also do Biodynamic compost, and will custom blend compost to order (high shellfish content for the wineries, for example.) Back to the Earth!
One note of major interest: Biobags. They have to spend over $1/4 million a year picking those bags out of their machinery. Unfortunately, the decomposition time on those is too long for the 60-day max turnaround at Jepson. In my own experience, they are still in your garden compost for at least two years, but in the trash they will at least break down eventually.