(a) Conditions exist that are beyond the control of the persons applying for the variance;

(b) Special circumstances render strict compliance unreasonable, unduly burdensome or impractical due to special physical conditions or cause;

(c) Strict compliance would result in substantial curtailment or closing down of a business, plant or operation; or

(d) No other alternative facility or method of operating is yet available.

(2) The commission by rule may delegate to the Department of Environmental Quality, on such conditions as the commission may find appropriate, the power to grant variances and to make the finding required by subsection (1) of this section to justify any such variance.

(3) In determining whether or not a variance shall be granted, the commission or the department shall consider the equities involved and the advantages and disadvantages to residents and to the person conducting the activity for which the variance is sought.

(4) A variance may be revoked or modified by the commission. The commission may revoke or modify a variance if it finds:

(a) Violation of one or more conditions of the variance;

(b) Material misrepresentation of fact in the variance application or other representations of the variance holder;

(c) Material change in any of the circumstances relied upon by the commission or department in granting the variance; or

(d) A material change or absence of any of the circumstances set forth in subsection (1)(a) to (d) of this section.

(5) The procedure for denial, modification, or revocation of a variance shall be the procedure for a contested case as provided in ORS chapter 183. [1977 c.511 §2]