(1) In establishing the extraordinary volume adjustment, unless the site operator and generator of the extraordinary volume agree to a contract disposal rate, one-half of the extraordinary volume delivery shall be priced at the maximum disposal rate and one-half shall be priced at the site operator's incremental cost to receive the delivery. Such incremental cost shall be determined in the initial rate proceeding.

(2) For purposes of the subsequent calculation of the volume adjustment, one-half of the total extraordinary volume shall be included in the calculation.

(3) This section shall only take effect following a finding that the site operator is a monopoly pursuant to RCW 81.108.100.