March 4, 1991


MEMORANDUM

SUBJECT:  Particulate Matter from Surface Coal Mining

FROM:     Joseph A. Tikvart, Chief
          Source Receptor Analysis Branch (MD-14)

TO:       Steve Rothblatt, Chief
          Regulation Development Branch, Region V


     The Model Clearinghouse has reviewed your issue regarding
the use of ISC for the Vermillion County Indiana PM-10 SIP.  You
point out that a major source of PM-10 in the area is a surface
coal mine and, given the provisions of Section 234 of the CAAA,
you question whether EPA can permit the use of the ISC model for
the SIP.

     Our position has always been that ISC is applicable, as a
refined model (not a screening technique), to fugitive dust
emissions from surface coal mines.  There is a school of thought
that the use of ISC, along with the AP-42 emission factors, for
surface coal mine fugitive emissions may lead to overprediction. 
If this were the case it seems to us that use of the
model/emission factors would still be protective of the NAAQS. 
Thus, from a purely technical standpoint we have no problem with
the use of ISC for regulatory modeling of the surface coal mine
emissions in Vermillion County.    
    
    My understanding of the Vermillion County situation is that
the State would like to use the model.   However, whether or not
Section 234 allows the State the option of using ISC on surface
coal mines until the study mandated by that section is completed
is a legal question.  We recommend that you contact OGC (Vickie
Patton) to seek resolution of this legal aspect of the issue.
      
     If you have any questions please contact Dean Wilson at 629-
5683.

cc:  R. Dunkins
     G. Felix
     V. Patton
     F. Renner
     D. Stonefield