(A) It shall be unlawful to operate, cause, suffer or allow, the operation of any source of sound or to project a sound or noise across a real property boundary in such a manner as to create an L50 A-weighted sound level which exceeds the limits set forth for the receiving land use designation in Table 1 when measured at or within the property line of the receiving land use designation.
(B) Such a sound source would constitute a noise disturbance. For the purposes of this chapter, the L50 shall be the sound, which exceeded for more than 50% of any measurement period which shall be not less than ten minutes when measured at or within the boundary of a property within the receiving land use district and as a result of a source of sound being located on some other property.
(C) For the purposes of this chapter, the L50 may be established by recording the instantaneous A-weighted sound level using the slow meter response at equal intervals of ten seconds. The resulting sound level sample that exceeds half the samples will be taken as the L50. Equally, for the purposes of this chapter, unless otherwise established by measurements, if the Leq is measured instead of the L50, the L50 shall be taken to be two decibels less than the measured equivalent sound level of Leq.
Exterior Sound Level Limits for L50 Sound Levels by Receiving Property
Receiving Property Designation | Time | L50 Sound Level Limit (dBA) |
Institutional Includes the following designations: Community Facilities, Recreational, Agricultural and Open Space | 7:00 a.m. -10:00 p.m. | 65 dBA |
10:00 p.m. -7:00 a.m. | 60 dBA | |
Residential Includes all Residential Multi- Family, PUD and MXD | 7:00 a.m. -10:00 p.m., Sunday through Thursday 7:00 a.m. -11:00 p.m., Friday, Saturday, legal holidays 7:00 a.m. on New Year’s Eve -12:30 a.m. New Year’s Day. | 65 dBA |
10:00 p.m. -7:00 a.m., Sunday through Thursday 11:00 p.m. -7:00 a.m., Friday, Saturday, legal holidays 12:30 a.m. -7:00 a.m., New Year’s Day | 60 dBA | |
Commercial Includes all business districts | 7:00 a.m. -10:00 p.m. | 70 dBA |
10:00 p.m. -7:00 a.m. | 65 dBA | |
Industrial | 7:00 a.m. -10:00 p.m. | 80 dBA |
10:00 p.m. -7:00 a.m. | 80 dBA | |
(D) The maximum exterior A-weighted sound level or Lmax measured during a period of not less than ten minutes using the slow meter response shall not exceed the L50 sound level limits specified in Table 1 by more than ten dBA.
(E) Within a multifamily dwelling, it shall be unlawful to create or permit any noise that exceeds the L50 and/or Lmax sound level limits specified in Table 1 and division (D) reduced by ten dBA.
(F) In addition to the limits of Table 1 and division (E), for any sound source which impacts residential, public space, or institutional property, the maximum (Lmax) allowable exterior sound level limits for the individual unweighted octave bands measured using the slow meter response whose centers are 63, 125, 250 and 500 Hertz shall not exceed 65 dBA.
(G) District boundaries. When a noise source can be identified and its noise measured in more than one land use designation, the pressure level limits of the most restrictive use district shall apply at that designation boundary.
(H) The burden shall be on any person contesting the equivalent sound levels to establish the actual equivalent noise level by clear and convincing evidence.
(Ord. 1486, passed 6-16-04)