As with any survey, the more samples the greater the confidence level in the final product.
The noted
garbologist William Rathje wrote a story about a study involving a dietary
survey of people who lived in a retirement community located in Arizona. As with
any Neilson-type survey, researchers provided the members of the community with
a diary to log all food and beverage consumed within a specific time period. The
researchers, however, took the added step of taking the garbage generated at
homes of these survey subjects during that same time frame and segregated,
weighed, and logged all categories. When the researchers compared the diaries
with the results of the waste characterization, they found that the survey
subjects had drastically underestimated the amount of alcohol consumed and
seriously overestimated the amount of vegetables eaten. Here was a case where
the characterization of the waste from these survey subjects acted as a check
and balance to the subjective traits of human nature. There is an objective
quality to the makeup of trash that speaks volumes to the social habits of waste
generators. The best solid waste employees, whether formally educated or not,
tend to be self-taught sociologists estimating the social traits of their
customers.
Waste
characterization studies define the composition of a wastestream and tell us
what type of items we discard. These studies can take a bead on specific waste
generation events, such as a music concert, or all that is generated in a
specific geographic area known, by some, as “waste sheds.” The items studied can
range from the delicate to the indestructible, from the ugly grime of the
indeterminable to such precious bounty as aluminum. These studies are what we
make of them—to be used, hopefully, for the better management of waste or,
unfortunately, to sit upon a shelf as a memento to an unfulfilled hope used
sparingly as a statistical resource when answering questions from the public,
the press, or a political body.
Professionals
in the field of waste characterization may start at one of two conceptual
methodological ends and ease toward the center, depending upon the size,
complexity, and funding available to complete the objective. At one end of the
scale, a modeling strategy sits that extrapolates the details of a wastestream
from broad economic indicators and manufacturing statistics to estimate waste
generation for a specific jurisdiction. The EPA and its consultant, Franklin
Associates, call this method a “materials flow methodology” that uses “data
gathered from industry associations, key businesses . . . and supported by
governmental data from sources such as the Department of Commerce and the US
Census Bureau.” The flow of goods, allowing for adjustments in imports and
exports, is estimated, as is the life expectancy of such goods. These variables
are calculated so as to take a broad swipe of the brush upon the national canvas
of waste, defining an order of magnitude. This “top-down” view of waste
generation and flow has its roots with the Public Health Service and its
successor, the EPA’s Office of Solid Waste (Municipal Solid Waste In The
United States: 2005 Facts And Figures, Environmental Protection Agency,
pages 2 and 23).
 |
| Waste characterization studies define the content of the wastestream. |
On the other
end of the methodological scale, men and women in Tyvek suits wearing latex
gloves and breathing through respirators spend their time sifting among 200- to
200-pound sections from truckloads of trash, filling buckets of predetermined
categories, weighing them, and carefully inputting the data for further
statistical analysis. This method builds a picture of the wastestream a pixel at
a time so that the image ultimately drawn has a defined and supported definition
to its shape that will instill a high level of confidence in the picture the
numbers paint. This “bottom-up” approach consumes more time and labor than the
“top-down” methodology.
The city of
Seattle has been doing the bottom-up methodological approach since 1988 on three
substreams: commercial, residential, and self-haul. Table 1 is taken from the
city’s 2006 “Residential Waste Stream” study done with the assistance of
Cascadia Consulting Group Inc. The table shows the number of samples for each of
the waste characterization studies of the three substreams of waste. The Seattle
Public Utilities, the agency overseeing these studies, has maintained a strong
commitment to this activity since 1988.
However, not
all solid waste managers may be employed by an agency or jurisdiction that has
either the commitment or the funds to support a waste characterization study
with a high level of sampling. Financial pressures on governments appear to be
increasing at an exponential rate, causing policymakers to look for creative
ways to estimate the character of their waste.
The EPA’s data
predict this very problem: “If resources are not available to adequately
estimate these [waste] materials by other means,” the authors of the study
write, “local planners may turn to the national data” (Municipal Solid
Waste In The United States: 2005 Facts and Figures, page 21). The
authors do point out, however, that this would only be a ballpark estimate that
would not take into account climate variation, scope of the wastestream of
individual facilities, cultural and economic differences in purchase and
disposal practices, commercial activity, and local and state regulations that
may influence the wastestream.
Less-intensive
options, therefore less costly, can be used to estimate the composition of a
wastestream without hand sorting. These include the review of similar studies,
as well as direct inquiry and observation.
Don’t reinvent the
wheel—Other communities have performed waste characterization
studies that could possibly be used to provide an estimate of a different
jurisdiction’s waste-stream. Parameters of the other study and its location must
be carefully reviewed to ensure that one is comparing similar situations. First,
the correct substream must be reviewed. If a solid waste manager is looking to
find out the type of material single-family units are generating, for instance,
then a waste characterization study of commercial waste will not help. Second,
the jurisdiction that performed the study may have advanced recycling programs
that divert considerable material, such as greenwaste, or, for example, has a
bottle bill that transfers plastic and glass bottles out of the disposal stream
and into the recycled stream. Significant programs diverting recyclables out of
the disposal stream will show considerable differences from a jurisdiction that
does not have such programs or vice versa. Third, demographic and cultural
differences can create variations in purchase and disposal habits. Large
immigrant populations, for instance, may have different dietary habits that
could contribute more or less foodwastes to the total waste shed. Fourth,
climate conditions will affect the level of material in the wastestream in terms
of greenwaste and in terms of potentially destructive natural forces. In other
words, Fargo, SD, may not have the same level of greenwaste as Kauai, HI, or
where tornadoes regularly spin through communities ripping trees and bushes out
of the ground as if they were carrots in the garden.
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| Purists may argue that only hand-sorts should be used. |
Look—If
a community does not wish to expend the funds to systematically segregate and
count the waste from a specific or multiple substreams, then one can estimate
the material in loads at the disposal points by visually seeing them dumped and,
if need be, spread out and estimated. Local public waste auditors, who go to
businesses free of charge to help the commercial community lower its disposal
costs and increase its diversion rate, have learned to do quick estimates of
materials in dumpsters and items in the work place so as to provide projections
to business owners on how to cut down on quantity disposed and divert more. This
skill can be expanded to all generators. Getting out of the office to look at
the flow of materials with an eye toward counting the number of trucks and
estimating percentage of material in a load can provide an order of magnitude
that would be helpful in judging the effectiveness of potential waste management
programs.
Ask—The
local waste market, if not the national one, is made up of a close-knit group of
individuals who make it their business to know market share. Asking the owners
and mangers of hauling, disposal, and processing operations what is done with
the material generated in the jurisdiction will unravel a plethora of threads
that need to be followed. Some of these threads will represent nothing more than
a strategy of misdirection, some will end in a tangled web making a Los Angeles
freeway interchange look rational, but others will lead to unknown processors,
to non-permitted disposal and processing facilities, to back-haul operations,
and to once-unknown pilot programs handling a portion of the waste. Telephone
surveys of waste receivers and generators can provide tonnage data that will
help to build a more complete picture of a jurisdiction’s waste flow. Asking
questions can lead to interesting discoveries about the flow of waste.
States Help
States have
attempted to assist localities with waste characterization studies. In 1988, for
instance, the State of Florida passed a solid waste management act setting 30%
as its recycling goal. The state provided up to $20 million a year to help
localities meet this goal and required all of its 67 counties to perform waste
characterization studies in order to develop a baseline for meeting the
recycling goal. The faucet that funded these individual waste characterizations
was wrenched shut, but in 2001 the State of Florida Department of Environmental
Protection gave an Innovative Recycling Grant to Pinellas County, which
partnered with several other jurisdictions. Together they hired the services of
Franklin Associates and Kessler Consulting to create a waste calculator built
upon a merging of a materials flow methodology, top-down, and hand-sorts,
bottom-up, held in four of the participating counties and 10 other Florida
samplings that had already been performed.
A Florida
county waste manager can go to and follow the simple instructions to input
demographic, recycling, and total tonnage information and get, in return, a
waste characterization for that county
(www.dep.state.fl.us/wastecalc/fdepcountydata.asp)
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| At one end of the methodoligical scale, men and women in Tyvek suits sift through trash, filing buckets with predetermined categories. |
Georgia’s
Department of Community Affairs also recognized, and says on its Web site, that
“[t]he cost and level of resources associated with conducting these [waste
characterization] studies are prohibitive for many counties.” This state office
hired R.W. Beck to develop a waste composition computer model for local waste
managers to utilize
(
www.gasolidwaste.org/GADCAWebCalc/index.aspx).
As with so many
things waste-related, the California Integrated Waste Management Board (CIWMB)
provides a fairly comprehensive Web site for waste characterization data. Along
with the CIWMB’s waste characterization database, the site includes six pages
and links to more information describing protocols for sampling at landfills and
where the waste is generated.
In 1999, the
CIWMB spent $635,700 for a waste characterization study, followed by $316,650
for another in 2003. The second study was less expensive, in part, because the
CIWMB opted not to hand-sort at the site of the commercial generator of waste.
It chose to do the sorting at the disposal site. Each study focused on three
generators: commercial, residential, and self-haul. The results are shown in
Table 2, as taken from the CIWMB’s “Update of California Waste Characterization
Data” December 2004.
The CIWMB is
currently performing another waste characterization study to update and compare
with those done previously.
Local
Jurisdictions: Seattle
Since 1988,
Seattle’s Public Utilities has performed consistent waste characterization
studies using the bottom-up methodology. It follows a four-step process.
Step 1 is that
of developing a sampling plan dedicating two-thirds of the sampling to
residential single-family waste and one-third to multifamily waste. A schedule
of sampling was developed for the calendar year. During each month there would
be two or three consecutive days of sampling randomly chosen.
Step 2 entails
the random selection of vehicle routes from each of the areas to be sampled. The
hauling contractor would be called on the day of sampling to have a randomly
chosen truck deliver material to the sampling location.
Next, the
collection vehicle chosen goes to the sampling location and is verified as being
the correct truck from the correct route. The material is unloaded onto the
floor and about 250 pounds is separated out into 83 component categories.
Finally, field
researchers build the information into a database and aggregate the sampling
using annual waste tonnages to divine the waste characterization of the targeted
wastestream.
Tables 3 and 4
show the changes in waste characterization of residential disposed over time in
the city of Seattle. The city decided to ban recyclable items, such as fiber,
from the wastestream, based in part on the findings of these waste
characterization studies.
Seattle also
broke down its study to show the disposal habits of single-family as well as
multifamily dwellings. Single-family units, the study found, produced a higher
percentage of foodwaste than did multifamily dwellings. Single families also
doubled the output of disposable diapers but newspapers made the top ten items
disposed by residents of multifamily units only.
Seattle studied
the waste coming from the commercial sector as well. It set up a sampling regime
for loose rolloff trucks, compactor rolloff vehicles, rear-loaders, and
front-loaders. The field researchers worked with the haulers to account for the
type of generator so it could develop composition by generator types, such as
educational institutions, health care facilities, hotels, manufacturing,
offices, retail, transportation industry, wholesale, and mixed commercial
generators. Tables 6 and 7 compare the results of aggregated percentages done in
various years. Construction, demolition and land clearing dropped since the
first study, as did paper, but organics have increased.
City
and County of San Francisco
Whether it is
simply the foreshadowing of expectations or fact, people see the city and county
of San Francisco as pushing the proverbial envelope, whether it is in politics,
in culture, or in trash. The jurisdiction’s relationship with its hauler, Norcal
Waste Systems Inc., is unlike any other in the nation: The jurisdiction’s
long-term disposal contract, based on total volume, creates a financial
incentive for the jurisdiction to divert waste away from burial. The local
culture and political institutions support the aggressive goals of 75% landfill
diversion by 2010 and zero waste by 2020 that the San Francisco Department of
the Environment has advocated.
Robert Haley,
with the city’s department of the environment, uses “these characterization
studies to design programs and policies.” Approximately every seven years, the
department sponsors a study at the cost of about $150,000 for waste disposal
characterizations and $75,000 for diversion characterizations. The most recent
was released in March 2006 and uses a mixture of hand-sort sampling and visual
characterization. Table 8 shows the number of samples from each waste sector
utilizing each method.
The visual
characterization method may sound hokey to those wearing pen protectors in their
breast pockets, but systemizing this art into a skill through standard operating
procedures can provide valuable information at a reduced cost. Field technicians
would have the material dumped, spread out if needed, and volume estimates made.
For instance: “If a 20-cubic-yard load appeared to hold 5 cubic yards of
foodwaste and 15 cubic yards of prunings, then it was recorded as 25% food waste
and 75% prunings. The differing densities of materials were taken into account
in subsequent calculations, not during the actual observations” (San Francisco
Department of the Environment, Waste Characterization Study: Final
Report, March 2006, Appendix C: Waste Sampling and Methodology, page
C-6). If materials were in opaque
bags, the bags were then opened and the contents spread out so they could be
seen.
An interesting
aspect of San Francisco’s waste study is its unflinching look at city
operations. Whether intended or not, waste characterization studies do not
regularly underscore waste from specific operations, especially if those
activities do not have waste management as their primary duty. Yet, the shining
city by the bay does not mitigate when it comes to its own jurisdiction’s
operations. It shows, for instance, that the housing authority disposes of trash
made up of 19% old corrugated containers and kraft bags and another 14% from
prunings. Thirty-one percent of the loads leaving the Muni Yard, for instance,
have low-grade paper, with another 20% made up of old corrugated containers and
kraft. This pinpoint characterization can help to implement in-house recycling
programs.
Policy Makers and Waste Characterization Studies
Rathje’s story
of using waste characterization as a check on human nature is important in this
sense: The characterization of specific wastestreams can be used to check and
balance the effectiveness of programs, policies, and educational outreach. These
studies can provide tangible, not anecdotal, evidence to the effectiveness of
those activities funded with increasingly limited public resources. Yet, the
studies can be done, as San Francisco has shown, by using multiple techniques to
help keep the costs low and still provide valuable information.
Purists may
argue that only hand-sorts should be used in these studies, whereas others will
debate the value of the resources expended for the benefits gained. The battle
between the ideal and the contingent is as old as the debates between Plato, the
teacher of the ideal, and Aristotle, the pesky student who continually reminded
his teacher of everyday human contingencies. The debate will always be there,
and solid waste managers must weigh the benefits versus the costs when
contemplating the strategies to perform a waste characterization study.
Charlie Scott
has been doing waste characterizations for decades and is widely respected by
both his competitors and clients across the country. He advises policymakers to
think through the purpose of these studies before enacting them and to ask
themselves the following questions:
- What are the study’s objectives? Is the success of a program being
measured or are potential programs being discovered?
-
Are there going to be decisions based on such a study? Will facilities,
for instance, be built based on the findings?
The answers to
these questions bring to the fore the level of confidence a policy maker needs
to have in the data. The greater the need for confidence in the numbers the more
precise the study needs to be. Many of the reports that stay closed and on the
shelf are those where the goals were not defined ahead of time.
Scott
also believes that waste managers hinder the project when they stipulate, in the
request for proposals (RFP), the precise methodology to be followed. Sometimes,
he says, the RFP will go so far as to state the number of samples to be
performed. This, he correctly says, squelches possible innovative techniques
that would otherwise be proposed for achieving the objective of the waste
characterization while reducing costs. Such RFPs, Scott believes, should break
out, not jail in, ideas of how best to reach the clear objectives of the waste
characterization study.