Re: scheme: fly ash in concrete

[Sam McClintock <mac@ensanity.com>]

> 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.

Agreed, but for MSW and similar ash use, I have yet to see anything remotely
approaching a large increase (some change, but small).  The bigger problem and
threat are still the emissions from any cement plant, regardless of applications and
uses.  Have a long way to go, despite new rules, before these sources are adequately
controlled.

>  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.

I would also add that cement dust in general has little risk studies associated from
that perspective alone, and again, cement dust already, with no help from fly ash,
already contains these things.

> 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.

I have seen similar elsewhere, but: a) power plant vs MSW or Haz waste ash,
different perspective and then some.  Similar pollutants, but much different levels.
b) oddly enough, sometimes the shale sources have large trace pollutant problems,
such as arsenic. Just trading one pig for a larger pig - the meal is still the same
and not a lot of difference.

I, for one, would be much happier if the force of law (and concern) were placed on
upgrading air pollution control equipment in cement kilns, not what is fed into
them.  Regardless of feed, they are dirty sources.

Regards, Sam