Re: scheme: fly ash in concrete

["Alex J. Sagady & Associates" <ajs@sagady.com>]

At 12:16 AM 8/4/1998 -0400, you wrote:
>>       I'll put in my 2c here. Sam, the point is that the fly ash FROM
>> INCINERATORS is some of the most toxic crap on earth. It's loaded with
>> dioxin, mercury, cadmium, lead, arsenic, and a host of other super-toxins,
>> both soluble and non-soluble. Fly-ash usage schemes all share the same
>> problem as all toxic waste usage schemes: 1. It justifies and cheapens the
>> disposal of toxic waste and 2. It appears to hide the toxic waste but the
>> toxins eventually leach out.
>

First, power plant fly ash being used as part of the cement making
process is extremely common.   One potential problem  with it, however, 
is increasing the amount of radioactive radium and thorium that is 
incorporated into cement used in buildings, and subsequent emissions
of radioactive decay products to interior spaces.

For dry scrubber controlled power plants that get some reduction of 
mercury emissions by virtue of collection in baghouse dust, and for 
MSW incinerator ash, the use of these materials in cement kilns will 
likely cause cross media transfer of mercury and subsequent emissions
from kiln stacks.

To the extent that metal toxicants  introduced in fly ash are volatilized
and end up in kiln dust, you will again introduce the potential to 
exacerbate and/or transfer problems in the case of 
semi-volatile metals.

Although the hi pH of cement and cement kiln dust tends to reduce
much of the potential leaching problem, I understand that lead 
chlorides have a  leaching window at high pHs but I don't have 
any details.    All discussion of metals in cement that deals only
with leachaete related issues completely discounts other 
pathways of exposure, including inhalation and occupationally
related exposure pathways.  EPA presently does not have
adequate or approved protocals for determining risks from 
inhalation exposures to metals in hazardous and industrial wastes
including cement kiln dusts.   In general, risk assessments in EPA's
permitting of 
cement kiln hazardous waste combustors has ignored 
risks associated with cement kiln dust management and disposal.

In addition, physical transport of 
particles contain toxics into water ways is also a mode for 
transport into aqueous systems.

>My 2 cents worth -> cement already contains all of this: metals, dioxins, etc.
>When you add a few pounds of ash per hour to something drawing 200 tons per
>hour or more, you are not impacting the overall makeup of  the cement and any
>significant fashion.  And since I don't see a whole bunch of leachate horror
>stories from cement (some but few), just as with glass and chromates, then what
>

Up in Alpena, MI, Lafarge Corporation has completely replace shale use
with very large amounts of power plant fly ash at addition rates which are
much larger than you cite.


>are we talking about?   The justification of disposal that will have to done
>anyway, in a concentrated area, susceptible to leaking? That we have
>alternatives that somehow overlook recycling problems or long-range transport
>for disposal?  ????
>
>Sam
>

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Alex J. Sagady & Associates        Email:  ajs@sagady.com
Environmental Consulting and Database Systems
PO Box 39  East Lansing, MI  48826-0039  
(517) 332-6971 (voice); (517) 332-8987 (fax)