10.01.070 Noise prevention.
(1) Applicants for permits for the building of new commercial or industrial structures shall be advised by the Department of Planning and Development Services that Snohomish County has passed and enforces a noise ordinance. The department shall provide them with information regarding chapter 10.01 SCC. Persons building new commercial or industrial structures are urged to plan to address noise issues in their building and site design, particularly when the noise will impact residential areas in the evening and at night.
(2) The standards provided in chapter 10.01 SCC represent the minimum protections for citizens from noise which are deemed appropriate. The county is aware of technologies and techniques which would reduce the impact of noise on citizens even further, but has chosen not to require them due to the impact on existing commercial and industrial uses. The fact that a new commercial or industrial use will meet the requirements of this code does not preclude other steps for noise abatement being required by the county when considering Conditional Use Permits and making SEPA determinations.
(3) New Residential Structures. In situations where the general conditions within a residential plat or short plat applied for after the effective date of this chapter indicate that noise from existing airports or interstate freeways may cause the exterior noise level anywhere within the proposed plat to exceed an Ldn of 60 dB(A), buffering or other mitigating measures may, prior to the approval of the preliminary plat, be required to be incorporated into the design and construction plans of the site and structure which are capable of reducing sound inside each home (with windows closed) to a level no higher than a Ldn of 40 dB(A). The following factors shall be considered in making a determination to require such mitigation measures:
(a) Whether reasonable noise mitigation measures are available, and
(b) Whether the financial impacts of the mitigation measures are disproportionate to the overall cost of the project, and
(c) Whether the benefit outweighs the cost.
(4) Arterial Street Improvements. In residential districts where arterial street improvements will be constructed in a new location or there is physical alteration of an existing arterial which significantly changes either the horizontal or vertical alignment or increases the number of through-traffic lanes, the county shall consider having a noise analysis done by a qualified person if, when measured:
(a) The existing noise level (maximum hourly Leq) exceeds 67dBA, or
(b) The projected noise level (maximum hourly Leq) is expected to increase beyond 67dBA, or
(c) The exterior noise level is expected to increase by 10 dBA or more as a result of the project.
In determining and measuring noise impacts, measurements should be taken from those exterior areas where frequent human use occurs.
(5) In deciding whether spending on noise mitigation measures related to arterial street improvements will be approved, the council and county administrative agencies shall consider the following factors:
(a) Whether reasonable noise mitigation measures are available, and
(b) Whether the financial impacts of the mitigation measures are disproportionate to the overall cost of the arterial improvement project, and
(c) Whether benefited property owners contribute to the cost, and
(d) Whether the benefited community is supportive of mitigation measures, and
(e) Whether the existing noise level was near or above 67dB(A) before or after the proposed arterial street improvements, and
(f) Whether a cost-benefit analysis shows the benefit to outweigh the cost.
(6) Violations of this section shall not be subject to enforcement under SCC 10.01.080(2) and (3). (Added by Ord. 97-023 § 1, June 4, 1997, Eff date Jan. 1, 1998).