(Adopted: December 3, 1976)

                                       Rule 901

          (a)  AFFECTED FACILITY means any apparatus to which a standard is
               applicable.  An  existing  facility,  upon   reconstruction,
               becomes an affected facility, irrespective of  any change in
               emission rate.

          (b)  COMMENCED  means that an owner or operator has undertaken  a
               continuous program  of  construction or modification or that
               an  owner  or  operator  has   entered  into  a  contractual
               obligation to undertake and complete,  within  a  reasonable
               time, a continuous program of construction or modification.

          (c)  CONSTRUCTION means fabrication, erection, or installation of
               an affected facility.

          (d)  FIXED  CAPITAL COST means the capital needed to provide  all
               the depreciable components.

          (e)  MALFUNCTION  means any sudden and unavoidable failure of air
               pollution control  equipment  or  process  equipment or of a
               process  to  operate in a normal or usual manner.   Failures
               that are caused  entirely  or  in  part by poor maintenance,
               careless operation, or any other preventable upset condition
               or preventable equipment breakdown shall  not  be considered

          (f)  MODIFICATION means any physical change in, or change  in the
               method of operation of, an existing facility which increases
               the  amount  of  any  air  pollutant  (to  which  a standard
               applies)  emitted  into  the atmosphere by that facility  or
               which results in the emission of any air pollutant (to which
               a  standard  applies)  into the  atmosphere  not  previously
               emitted, except that:

               (1)  Routine maintenance,  repair, and replacement shall not
                    be considered physical changes, and

               (2)  The following shall not  be  considered a change in the
                    method of operation unless such changes are contrary to
                    the provisions of a permit:

                    (A)  An  increase  in  the  production  rate,  if  that
                         increase  can be accomplished  without  a  capital
                         expenditure  on  the  stationary source containing
                         that facility;

                    (B)  An increase in hours of operation.

          (g)  OWNER  OR  OPERATOR  means  any  person  who  owns,  leases,
               operates, controls, or supervises  an affected facility or a
               stationary source of which an affected facility is a part.

          (h)  RECONSTRUCTION means the replacement  of  components  of  an
               existing facility to such an extent that:

               (1)  The fixed capital cost of the new components exceeds 50
                    percent  of  the  fixed  capital  cost  that  would  be
                    required   to   construct  a  comparable  entirely  new
                    facility, and

               (2)  It is technologically and economically feasible to meet
                    the applicable standards set forth in this part.

          (i)  SHUTDOWN means the cessation  of  operation  of  an affected
               facility for any purpose.

          (j)  STARTUP  means  the  setting  in  operation  of any affected
               facility for any purpose.