(1) A subprevailing wage certificate shall specify, among other things, the name of the worker with a disability, the name of the employer, the duties to be performed by the worker with a disability, the percentage of the prevailing rate authorized to be paid, and the period of time during which that percentage of the prevailing rate may be paid. A certificate shall also indicate that the percentage of the prevailing rate to be paid a worker with a disability shall change to reflect an increase or decrease in the worker's productivity when the worker's productivity is determined to change.

(2) A subprevailing wage certificate shall be effective for a period of one year or less as designated by the director or an authorized representative of the director. A worker with a disability employed under such certificate may be paid at the specified percentage of the prevailing rate only during the effective period of the certificate.

(3) Notwithstanding the requirements of chapter 49.46 RCW and its administrative regulations, the percentage of the prevailing rate authorized to be paid shall be fixed at a figure designed to reflect adequately the percentage of productivity at which the worker with a disability functions.

(4) Any money received by a worker with a disability by reason of any state or federal pension or compensation program for persons with a disability shall not be considered as offsetting any part of the wage or remuneration due the worker with a disability by the employer.

(5) A worker with a disability shall be paid not less than one and one-half times the rate specified in the subprevailing wage certificate for hours worked in excess of forty hours per workweek or eight hours per day.

(6) The terms of any subprevailing wage certificate, including the percentage of the prevailing rate authorized to be paid, may be amended by the director or an authorized representative of the director upon written notice to the parties concerned, if the facts justify such amendment.