A publication of *Work On Waste USA, Inc.*, 82 Judson, Canton,
NY 13617 315-379-9200 **April 18, 1991**

Kay H. Jones worked for the consulting firm of **Roy F. Weston
**until early 1990 and now is the president of **Zephyr Consulting**
in Seattle, Washington. Jones was **Weston’s** consultant
for several incinerator projects including Detroit; South Philadelphia;
Preston, CT; Spokane, WA; Conshohocken, PA; and many others.**
**In a 4-8-91 letter to Scott Weiner, Commissioner of the
Department of Environmental Protection (DEP) in New Jersey, Dr.
John Healy, (PhD in statistics from Purdue U.) and Dr. Jerome
Stanshine (PhD in mathematics from MIT) identify a serious mathematical
error in a risk assessment performed by Kay Jones for the **Westinghouse**
incinerator proposed for Tinton Falls in Monmouth County. They
write:

“The mathematical error that has been identified results
in serious underestimates of the risks from incinerators. Dr.
Kay H. Jones, the expert hired by Monmouth County to lead the
risk assessment effort, has indicated that this error is part
of a standard way to do risk assessments.** Therefore, it is
likely that some, and perhaps all, of the incinerator risk assessments
previously filed with the state of New Jersey have been affected
by the technical error that we uncovered. Therefore, we recommend
that the DEP re-open all previously filed incinerator risk assessments
to determine if they have been contaminated by the technical error,
and correct for the error wherever it has been made.”**

**“**There are serious flaws in the risk assessment process.
These flaws have a large impact on a risk analysis and the conclusions
that might be drawn from a risk analysis. A risk analysis should
provide the community with a realistic assessment of the risks
of an incinerator. A major result of a risk analysis are estimates
of the chances of a dangerous amount of toxic emissions. In summary:

*** The current process could underestimate the risks by a factor
of 5, 10 or more.**

*** For risk assessment, the incinerator emissions should be
assumed to be at a high enough level so that very few incinerators
(perhaps 5 percent) emit higher levels than the ones used in
the calculations.**

**“Current Process.**** **No one knows in advance
how well an incinerator will perform, and exactly how much of
various toxins and carcinogens will be emitted into the air by
an incinerator. This can only be determined by taking measurements
after the incinerator is operational. Nonetheless, in order to
conduct a risk assessment, some estimates of performance of the
unbuilt incinerator must be made. These estimates are based on
historical data. Our understanding of the current process for
generating the estimates is based on a paper entitled *Review
of Analysis of Worldwide Resource Recovery Emissions Data and
the Implications for Risk Assessment* by Paul C. Siebert, Denise
Alston-Guiden, and Kay H. Jones and on comments by Dr. Jones to
the Monmouth County Risk Assessment Committee.

“In the above-mentioned paper, Dr. Jones calculates geometric
means and 95 percent confidence intervals for emissions of several
kinds of pollutants from incinerators. He assumes that geometric
mean is the best estimate of emissions, and that the 95 percent
confidence interval for the median is a conservative worst-case
estimate. This upper 95% confidence interval is used to bound
the risks of toxic emissions.**** ** However, what he refers
to as the ‘upper 95 percent confidence interval’ is
not the 95th percentile, and **this is a serious error. **The
following example may serve to illustrate the nature and seriousness
of the error.

__ “Example. __ Dr. Jones starts with the EPA Toxic
Equivalency Factors (TEFs) for twelve operational incinerators
with acid gas controls (see Table 2 in his paper):

0.050 0.178 1.716*

0.058 0.330 4.705*

0.067 0.354 7.524*

“He then calculates the ‘Upper 95% Confidence Interval’ for the EPA TEF (see his table 4) for these incinerators:

“Three of the twelve incinerators (twenty-five percent) have Toxic Equivalency Factors that are two, five and eight times Dr. Jones’ calculated ‘Upper 95% Confidence Interval.’ (Incinerators marked with asterisk). The upper limit of a 95% confidence interval does not represent a worst-case.

**“Dr. Jones’ ‘Upper 95% Confidence Interval’
does not provide a conservative estimate of how badly an incinerator
can perform. A quarter of the incinerators performed worse, one
of them eight times worse. They cannot be ignored. Dr. Jones’
analysis gives the wrong answer, not by a little, but by a lot.**

**“Better Analysis.**** **A better ‘worst-case’
estimate is easy to calculate. Dr. Jones uses a set of lognormal
distributions to model the collected incinerator emissions data.
We recommend using the same distributions. However, instead
of using his ‘upper 95 percent confidence interval’
for those distributions, we recommend using the 95th percentile.
For the twelve Toxic Equivalency Factors in the example cited
above, the estimate of the 95th percentiles comes out to be 5.58,
rather than 0.88 that Dr. Jones uses. With the 95th percentile,
we expect about 5% of the incinerators to have Toxic Equivalency
Factors worse than (greater than) 5.58. It is unlikely that a
new incinerator will have a Toxic Equivalency Factor substantially
greater than 5.58, and this number realistically bounds the risks.
Note that it is over 6 times the value used in the current process.

**“For risk assessment, the incinerator emissions (including
Toxic Equivalency Factors) should be assumed to be at a high enough
level so that very few incinerators (perhaps 5 percent) emit**
**higher levels than the ones uses in the calculation.”**

Video now available from Video-Active Productions

Route 2, Box 322, Canton, NY 13617 - 50 minutes, Cost: $25

Community composting is elegant, simple, successful, and replicable.
Filmed by Roger Bailey in Zurich, Switzerland, in February 1991,
Paul Connett interviews Thomas Waldmeir who heads up Zurich’s
community compost program initiated by the City of Zurich five
years ago. Currently there are 482 community composts in Zurich
which serve between 3 to 200 householders. The second part of
this video is a tour through a centralized 200 ton per day yard
waste compost facility run by the City of Zurich. Marcus Neiderman,
the director of the yard waste composting, stresses the importance
of source separation of materials by the customer bringing material
to the facility. He emphasizes that a compost that you can use
with a **“good conscience” **for garden plants, etc.,
**has to have up-front source separation **of plastic, metals,
“and anything that cannot be used for a good soil.”