(1) The following shall be exempt from the provisions of WAC 173-60-040 between the hours of 7:00 a.m. and 10:00 p.m.:

(a) Sounds originating from residential property relating to temporary projects for the maintenance or repair of homes, grounds and appurtenances.

(b) Sounds created by the discharge of firearms on authorized shooting ranges.

(c) Sounds created by blasting.

(d) Sounds created by aircraft engine testing and maintenance not related to flight operations: Provided, That aircraft testing and maintenance shall be conducted at remote sites whenever possible.

(e) Sounds created by the installation or repair of essential utility services.

(2) The following shall be exempt from the provisions of WAC 173-60-040 (2)(b):

(a) Noise from electrical substations and existing stationary equipment used in the conveyance of water, waste water, and natural gas by a utility.

(b) Noise from existing industrial installations which exceed the standards contained in these regulations and which, over the previous three years, have consistently operated in excess of 15 hours per day as a consequence of process necessity and/or demonstrated routine normal operation. Changes in working hours, which would affect exemptions under this regulation, require approval of the department.

(3) The following shall be exempt from the provisions of WAC 173-60-040, except insofar as such provisions relate to the reception of noise within Class A EDNAs between the hours of 10:00 p.m. and 7:00 a.m.

(a) Sounds originating from temporary construction sites as a result of construction activity.

(b) Sounds originating from forest harvesting and silvicultural activity.

(4) The following shall be exempt from all provisions of WAC 173-60-040:

(a) Sounds created by motor vehicles when regulated by chapter 173-62 WAC.

(b) Sounds originating from aircraft in flight and sounds that originate at airports which are directly related to flight operations.

(c) Sounds created by surface carriers engaged in interstate commerce by railroad.

(d) Sounds created by warning devices not operating continuously for more than five minutes, or bells, chimes, and carillons.

(e) Sounds created by safety and protective devices where noise suppression would defeat the intent of the device or is not economically feasible.

(f) Sounds created by emergency equipment and work necessary in the interests of law enforcement or for health safety or welfare of the community.

(g) Sounds originating from motor vehicle racing events at existing authorized facilities.

(h) Sounds originating from officially sanctioned parades and other public events.

(i) Sounds emitted from petroleum refinery boilers during startup of said boilers: Provided, That the startup operation is performed during daytime hours whenever possible.

(j) Sounds created by the discharge of firearms in the course of hunting.

(k) Sounds caused by natural phenomena and unamplified human voices.

(l) Sounds created by motor vehicles, licensed or unlicensed, when operated off public highways except when such sounds are received in Class A EDNAs.

(m) Sounds originating from existing natural gas transmission and distribution facilities. However, in circumstances where such sounds impact EDNA Class A environments and complaints are received, the director or his designee may take action to abate by application of EDNA Class C source limits to the facility under the requirements of WAC 173-60-050(5).

(6) Nothing in these exemptions is intended to preclude the department from requiring installation of the best available noise abatement technology consistent with economic feasibility. The establishment of any such requirement shall be subject to the provisions of the Administrative Procedure Act, chapter 34.04 RCW.