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What does an 80% diversion rate REALLY mean? Taking a closer look at San Francisco’s landfill discards.This entry was posted
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You may have heard that San Francisco diverts 80% of its discards from landfills. Jeremy Irons calls this statistic, and the city it applies to, a “source of hope” in his documentary, Trashed, which is about the ravages of global waste. Journalists around the world cite the 80% as a beacon, an exemplar, a benchmark, and a vision for the future.
Make no mistake, San Francisco is a source of inspiration in that it offers a robust, mandatory, and centrally organized system of recycling and composting to its citizens, on a large scale. While the city boasts many community based activities organized around reuse and backyard composting, the mass of what is called “diversion” from disposal in San Francisco is handled through one large, private sector program serving residents and businesses with recycling and organics collections. Because of these efforts, hundreds of thousands of tons of material are kept out of landfills each year.
But San Francisco’s famous 80% statistic has taken on a larger meaning in the imagination of urban sustainability, a meaning that transcends San Francisco’s smart approach to waste management. The 80% is mentioned as evidence of approaching zero waste, a metric of what can be done to reduce disposal in present day, and a benchmark upon which other cities’ efforts should be measured. Given its iconic status, and the frequency with which it is invoked, it is important to understand the anatomy of this 80%.
In contrast, a common statistic lamenting the wastefulness of Americans notes that “the average person generates over 4 pounds of trash every day.” This figure, which comes from the US EPA, is actually 4.4 pounds per day presently as of 2011, the most recent year for which statistics are published (US EPA 2013). Of that 4.4 pounds, 1.5 pounds per day is recycled or composted, and 2.9 pounds per day goes to disposal in landfills or incinerators. The US’s paltry diversion rate, by these measures, is 35% (US EPA 2013).
Might the 80% statistic mean that in San Francisco, 80% of 4.4 pounds, i.e. 3.5 pounds, is reused, composted or recycled each day, leaving a mere 0.9 pounds going to disposal? You might logically think that, but you’d be wrong. In fact, in San Francisco, the average person sends about 2.7 pounds per day to landfills. On per person basis, it would seem that record-setting San Franciscans send roughly the same quantities to the dump as their friends in other places in the US.
San Francisco’s 80% diversion rate is, in fact, a unique reflection of what the San Francisco Department of Environment counts, and how it calculates and publicizes what it counts. I present details below, but the bottom line is this. San Francisco’s diversion rate is so high because the city includes large quantities of very heavy construction materials (such as excavated fill and rubble, which are reused as infill and road base ) and biosolids (applied to agricultural land) as “diversion”. These materials, along with smaller (though very respectable) quantities of paper, metal, glass, and plastic recycling; and organics composting, total, on a per capita basis, nearly 12 pounds of stuff per person per day!
Other cities and countries don’t compile their municipal solid waste (MSW) diversion statistics this way. They typically only count reuse and recycling of post-consumer commodities (paper/cardboard, metal, glass, plastics, e-waste, textiles, furniture, etc.), along with composting, in their diversion rate calculation. Disposal and recycling of construction materials are accounted for separately, as are the fate of biosolids – aka sewage sludge.
It’s not that San Francisco’s recycling or composting achievements aren’t fantastic in and of themselves, but it is also not the case that its 80% rate really reflects 80% of garbage being kept out of landfills in the way that zero waste aspirants think of it. This paradox suggests, at the very least, that this 80% should not simplistically be held up as a metric of success to which others cities should be compared. In short, we need to think beyond the invocation of one rate, to ask tough, detailed questions about how waste generation and disposal are measured, how much Americans consume, and how knowledge is framed to occlude important details.
It is my hope that journalists and others reading this posting will take the time to understand the statistics, as opposed to repeating pre-packaged sound bites as erroneous facts. The future of urban sustainability depends on realistically understanding and carefully measuring flows of tonnages of different materials that are disposed of, or that can be reclaimed. Reuse, recycling, and composting are good but end of pipe methods of reclamation. Less cultivated, but potentially rich alternatives include laws to ban certain substances and assess fees or taxes on others; programs to reduce waste through product redesign; and even (in my opinion much less effective) voluntary efforts by consumers to buy less crap. Each of these approaches has its own difficulties, characteristics, economies, and ecologies. We need to understand them. The stakes are too high to leave to one towering, poorly comprehended percentage.
Where These Numbers Come From
San Francisco regularly publicizes its 80% diversion rate, as well as how much it sends to landfill. The latter statistic is required to be reported to the California state agency that regulates waste, Calrecycle. Aside from that, one must look far and wide for additional detail about materials and tonnages that make up this 80% diversion. Waste and Recycling News was an industry trade journal that sadly folded earlier this year. Before their demise, they conducted an annual survey of large US cities, asking questions that no other federal or state agency does. In 2013, their last Municipal Recycling Survey reported the following statistics for San Francisco:
A scan of Waste and Recycling News’s last Municipal Recycling Survey.
Detail on San Francisco from Waste and Recycling News’s Municipal Recycling Survey. Numbers show annual US tons.
You will note that these statistics list the diversion rate (80% combined residential and commercial) and the tonnages of different materials diverted (last six lines in the extract above). They also confirm San Francisco’s population (812,826). What they don’t show is how much was disposed of, but that is calculable from the data given. The figures show a total of 1,575,500 tons diverted. That is 80% of 1,969,375 tons of total generation, with 393,875 tons per year (the difference) representing the total waste going to disposal.
On a per person basis, this translates to 2.7 pounds per person per day of trash. If New York City sent the equivalent to disposal, it would be dumping nearly 4 million tons a year. In reality the tonnage is more like 6 million tons of commercial and residential trash combined (not counting construction and demolition waste), higher, but not as far apart as the NYC-sucks/SF-shines discourse, well-worn in the media, would lead you to believe.
You will also note that the nature of the very large category, called “other”, totaling 1,028,550 tons per year, is not detailed. I emailed the San Francisco Department of Environment to ask them about the composition of this very large category. They confirmed, by phone, that it was largely what is called in the waste business “inerts”, meaning rock, dirt, sand, and crushed concrete that is used in fill and basic construction operations, with some biosolids as well. They gave me a rough percentage attribution which I apply in the summary table below. According to the SF Department of Environment, the contribution of sexy types of diversion such as e-waste, textiles, mattresses, or furniture to this “other” category was negligible, not even amounting to a percentage point of diversion.
Table 1: Calculated by the author.
San Francisco is doing a great job of diverting a lot of stuff, of construction origin or otherwise, from the landfill. Why rain on this parade? The answer has to do with the potency that the 80% has in comparisons and applications far afield. The 80% has become a touchstone and a symbol. Yet it is, at least in part, a product of a certain approach to counting and classification that mobilizes the heaviest fractions of urban discards to tip the scales. As I detail in the calculations below, if we remove this massive quantity of sand, earth, rock, rubble, and sludge, it is probable that San Francisco is keeping 60% of its residential and commercial trash out of landfills, about half from composting , and the other half through traditional recycling. A great achievement in its own right.
This is an important figure, especially in conjunction with the still relatively high per capita disposal rate that abides, even with a lot of active recycling and composting. It is possible that this disposal rate includes some landfilled construction material. The calculations below remove the “other” diversion, and discount disposal by 12.2%, the fraction of disposed waste that was classified as construction and demolition debris in San Francisco’s 2006 Waste Characterization Study (City and County of San Francisco 2006). Reduced by this percentage, San Franciscans are trashing 2.3 pounds per person per day.
Table 2: calculated by the Author.
In fact, for a city diverting 80%, or even 60%, of its waste, even this discounted disposal rate is still pretty high. Let’s compare this disposal rate, which translates into 386 kg per person per year, to some other nations in the European Union, including a few looked to from the US as shining exemplars of sustainability (Germany, the Netherlands, Norway and Sweden) and a few not so shiny places (Malta, Iceland, Greece, Cyprus, and Portugal).
Table 3. Contribution of traditional recycling and composting to European diversion rates. Rates are calculated by the author from per capita kg statistics from Eurostat.
The graph above is compiled from Eurostat data (I have omitted some EU countries to make the graph more readable. Full source data is available here). Unlike the Europeans, who consider incineration (aka waste-to-energy) a form of recovery, I have calculated “disposal” as the sum of landfilling and incineration of municipal solid waste (which excludes inerts and fill). Diversion here is traditional recycling and composting. We see that the closest cousin to San Francisco in per capita disposal (stuff sent to a landfill or an incinerator) is Portugal, which reports a 20% national diversion rate. In Germany, the EU’s recycling superstar, which has a diversion rate of “only” 62%, people are disposing of 223 kg annually, with the Netherlands even lower.
Where does this leave us?
I have used what data is available to calculate a diversion rate for San Francisco that is comparable to a national diversion rate, or to statistics for other cities and towns. By this calculation, we find that San Francisco has a diversion rate of 60%, quite similar to Portland and Seattle (and Germany for that matter), all of whom use conventional methods for rate calculation. About half of this 60% comes from recycling of traditional commodities like paper, metal, glass and plastic; and the other half comes from collecting organics for composting. These achievements reflect the joint efforts of residents and businesses.
The fact still remains, however, that San Francisco is consuming a lot. San Franciscans are diverting a lot, and disposing a lot, all at once. And this brings up another thought to ponder. Success at diversion, at reuse/recycling/composting, can take place alongside rather hefty rates of disposal. Is this how attainment of zero waste should be approached?
Hey wait a minute!
At this point a lot of you may be getting ready to fire back in the comments page. Here are some logical potential responses, with my rejoinders:
1. San Francisco has a lot of commuters who come in from outside the city and thrown stuff away, that’s why the disposal rate is 2.7 pounds per person per day. (2.3 if we follow my method of discounting for estimated construction and demolition waste.)
Fair enough. San Francisco, like Boston, Dallas, Washington DC, and most other large cities in the US has a lot of commuters. So does Berlin, the capitol of the EU’s top recycling nation, Germany. Berlin reports a 40% diversion rate, and a per capita disposal that comes out to 1.7 pounds per person per day (Zhang et. al. 2013). Lower diversion rate, lower rate of disposing of stuff. In my mind this still argues for a critical review of the 80% statistic.
This is probably true. Research carried out by Columbia University and the folks at Biocycle suggests that the EPA undercounts disposal and overcounts diversion. If we go by their numbers, Americans are, on average, sending 5.3 pounds per person per day to the landfill or incinerator, recycling/composting 1.7 pounds, at a rate of 24% (Van Haaren et. al. 2010). There is no arithmetic way of relating the 80%:24% ratio to the 2.7 pound: 5.3 pound ratio, but the fact remains that the 80% statistic still occludes a lot of important information.
3. Celebrate, don’t critique! San Francisco is doing great things, and this type of critique only fuels the enemies of sustainable discards management/zero waste. (Enemies here typically include right-libertarian critics of public subsidy of recycling, ideologically motivated anti-environmentalists, firms in the waste-to-energy/biomass/biofuels industry; and lazy/skeptical/irresponsible/disheartened people, who must be shielded from any critique of recycling lest they “give up” on environmentally responsible activities).
This is an understandable perspective, which deserves consideration, but I disagree. What has driven me to write this essay are inquiries I receive from members of the media asking why we all can’t be like San Francisco, which keeps 80% of its garbage out of landfills, and represents a beacon of hope for the world. This posting is, first and foremost, for those journalists.
In fact, San Francisco would would still be considered a leader in diversion even at the 60% I have calculated; although it would be much harder to argue that they were near to zero waste. The point here is not to discount what San Francisco is doing, but to make the information more transparent – and ultimately more useful – for others to digest and incorporate into their understanding.
Posted by: Betty
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