October 16, 1991


MEMORANDUM

SUBJECT:  Dade County, Florida, Stack Height Increase

FROM:     Gwen Jacobs 
          SO2/Particulate Matter Programs Branch, AQMD  (MD-15)

TO:       Lew Nagler, Regional Meteorologist
          Air Programs Branch, Region IV


     I have received your October 1, 1991 memorandum regarding
the requested credit for a stack height increase at the Dade
County, Florida, Resource Recovery Facility.  Specifically, you
asked:

     Can the GEP regulations be interpreted to allow an increase
     in stack height up to GEP if plant-wide SO2 emissions are
     not more than 5000 tons per year, SO2 pollution control
     equipment will be installed, and actual emissions will be
     decreased?

     The answer is no; beyond the 65 meter threshold, there is
currently no other de minimis exemption for stack height
increases.  The important thing to note here is that 40 CFR, Part
51.100(hh)(2)(C)(v), or the discussion of sources emitting less
than 5000 tons per year, applies to other dispersion techniques. 
Stack height increases must still be justified either through
fluid modeling or through demonstration of a local nuisance
during periods of downwash conditions.  Likewise, the addition of
pollution controls will not exempt a stack height increase from
justifying that increase through the measures stated in the
previous sentence.  As a result, the proposed stack height
increase in Dade County must be justified through either fluid
modeling or demonstration of a local nuisance. 

     Please do not hesitate to call if you would like additional
clarification on this issue.  I may be reached at (FTS) 629-5295.

cc:  Gary Blais, MD-15
     Patricia Embrey, LE-132A
     Eric Ginsburg, MD-15
     Dean Wilson, MD-14