Each day, or part thereof, that dense smoke
is emitted in violation of this article shall be deemed to be a separate
violation, unless an extension of time to continue such violation
is granted by the Board therefor based upon a factually supported
claim that extensive alterations are required for the purpose of complying
with the provisions of this article and based further upon the promise
that such alterations will be made within such time as the Board may
determine to be reasonable. The granting or denial of such extension
of time shall, at all times, be discretionary with the Board.