November 4, 1994


MEMORANDUM

SUBJECT:  Model Clearinghouse Review of Modeling Approaches in the
          Steubenville-Follansbee Area

FROM:     Joseph A. Tikvart, Group Leader
          Air Quality Modeling Group (MD-14)

TO:       George Czerniak, Chief
          Air Enforcement Branch, Region V


     In response to your request, we have reviewed your comments
concerning a proposed approach for modeling various fugitive
particulate matter sources in the Steubenville-Follansbee area. 
Also, we have reviewed your alternatives for selected aspects of
the modeling study.  In general, we agree with your comments on the
proposed approach and your alternatives for this particular
modeling application for the Steubenville-Follansbee area only.   
The following are more specific comments concerning your request.

     We agree with your concern regarding the treatment of building
wake effects for the simple terrain modeling.  As you noted, the
proposed approach would potentially reduce the likelihood that
building induced downwash would be invoked for the simple terrain
receptors.  This is especially a concern if the intermediate and
complex terrain features are at a sufficient distance that maximum
predicted concentrations could occur in the simple terrain area. 
Based on previous conversations with you and Region III, we
understand this to be the case.

     We agree with your assessment that because of the distance to
the complex terrain, the proposed approach's failure to include
transitional plume rise should not affect predicted concentrations
in the complex terrain area.  Also, you note that the current
information on the emission release characteristics is inadequate
and that more information would be needed to support the use of the
proposed approach.  It is the Clearinghouse policy to defer to the
Regional Office issues associated with emission characteristics. 
Therefore, we would agree with your assessment that the proposed
approach would be acceptable for the complex terrain modeling
provided that Regions V and III are satisfied that adequate
information on emission release characteristics supports the use of
the proposed approach.

     We also agree with your alternative approach to use the BLP
model in its entirety for the simple terrain receptors for the
appropriate sources.  Again, this would depend on the Regional
Offices' acceptance of the information on the emission release
characteristics and whether this information supports usage of the
BLP model.  Your alternative approach would sum the predicted
concentrations from the ISC model for other nearby sources to
obtain a total concentration for the simple terrain receptors.  We
also agree with this method.

     In summary, we agree with your comments concerning the
proposed modeling approach and your suggested alternative
approaches for this particular application in the Steubenville-
Follansbee area.  As you know, this or any other procedure cannot
be recommended for generic use without more extensive technical
review as well as peer and public review.  

     If you have any additional questions or comments, please
contact me at (919) 541-5562 or Dennis Doll at (919) 541-5693.

cc:  A. Cimorelli, Region III
     D. Doll, OAQPS
     J. Irwin, OAQPS
     W. MacDowell, Region V
     R. Robinson, Region V
     M. Spink, Region III
     J. Summerhays, Region V