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[greenyes] Set Out and Participation Rates
Jeff Aluotto asks:

"Has anyone done any work comparing curbside recycling set-out rates to
actual participation rates?  Specifically, I'm wondering if anyone has
developed a rough way of estimating program participation rates by measuring
set-outs (the idea being that not everyone participating in a program sets
their bin out each week)."

This is actually a more complicated question than immediately meets the eye.

The three factors are the setout rate, the participation rate -- both of
which you refer to -- AND also the setout INTERVAL, which is the average
time between setouts by those who participate.

The setout INTERVAL is not fixed, but varies with local conditions, most
particularly the size of the recycle receptacle.  This is the case because
the typical container setout volumes do not fill a standard bin in a week,
but on the other hand, are not large enough to hold two weeks, resulting in
people setting out more frequently than they really need to.  Consequently,
in small bin programs (12-18 gallons), the average setout interval is
theoretically only 1.54 weeks between setout, which is not optimal. A survey
that we did of 8 such programs found 1.4 weeks between setouts, and one done
by the American Plastics Council found 1.6 weeks between setout. Larger
receptacle programs (such as large 24 gallon bags) theoretically could have
2.8 weeks between setouts, and our field observations found 2.3 weeks
between setouts.

I mention this digression because it is very important for system
savings...the longer the setout interval, the more payload per stop and the
fewer stops per ton collected, all of which produce a significantly lower
cost operation.  Our detailed studies found that 1.5 week setout interval
programs would on average require 13.3 truck routes for a 35,000 household
community, and only 10.3 trucks in a 2.3 week setout interval program, a 23%
reduction in collection costs.

You can find a fuller write up of it in an article we wrote for Resource
Recycling, "Improving the Efficiency of Curbside Recycling Collection,"
(April 1994).

But, to answer your question more directly, the conversion formula, once you
have a bead on your local setout interval is:

        Setout Interval X Setout Rates = Participation Rates

Using this formula, though, as noted above, demands an informed answer to
the setout interval question, rather than just grabbing a quick national
multiplier as is all too often done, such as the number 2 that is most often
given, but which I would strongly discourage.

(There are more subtleties to doing this right, but to avoid number
overload, let me stop this here and suggest that you pick up that article.)


Peter Anderson
4513 Vernon Blvd. Suite 15
Madison, WI 53705
Ph:    (608) 231-1100
Fax:   (608) 233-0011
Cell    (608) 438-9062
email: anderson@no.address

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