November 28, 1988







MEMORANDUM

SUBJECT:  Request for Use of ISCST and ISCLT Version 6.2 in 
          Formosa Plastics PSD Application

FROM:     Dean A. Wilson
          Techniques Evaluation Section, SRAB (MD-14)

TO:       James W. Yarbrough, Air Modeling Contact
          Region VI (6T-AN)


     In response to your request, the Model Clearinghouse has
reviewed your November 19, 1988, draft letter to Formosa Plastics
where you indicate that the Company may use ISC UNAMAP 6, Change
2 for its PSD modeling, since this modeling is to be essentially
completed by December 10.  We agree with your position and with
your draft letter; you have appropriately caveated the approval
to use Change 2.

     If you have any further questions, please contact me.

cc:  D. deRoeck, MD-15
     S. Reinders, MD-14
     Regional Modeling Contact, Regions I-V, VII-X (with incoming
       request and list of FY-89 Clearinghouse memoranda)