11.125.490 Noise control.
(a) Guidelines for the Design of Noise Control in Facilities of the Washington Suburban Sanitary Commission, revised July 1977, establish the property line goals to “ensure compliance with applicable regulations and to minimize the impact on existing noise environment where such impact could affect the public health and general welfare.” Goals related to achieving this compliance are given in the following table:
|
Zone |
Maximum Daytime Levels |
Maximum Nighttime Levels |
|---|---|---|
|
Residential |
55 dBA |
50 dBA |
|
Commercial |
62 dBA |
62 dBA |
|
Industrial |
62 dBA |
62 dBA |
Note: Ambient conditions may require more stringent goals.
*Maximum levels for noise containing pure tones, hums, whines, or impulses of a periodic character shall be five dBA below values listed in the table.
(b) Workplace noise control goals were established to ensure that WSSC personnel are not subjected to hearing damage risk and that noise levels in work environments are compatible with work activities. Goals related to achieving workplace compliance are given in the following table:
|
Workplace Activity Description |
Noise Goal |
PSIL* |
|---|---|---|
|
Machinery operation and maintenance |
85 dBA |
— |
|
Noisy environment with speech communications required |
85 dBA |
72 dB |
*PSIL is speech interference level equal to the average of the noise levels in the 500, 1,000 and 2,000 Hertz octave bands.
Sources of noise for exterior control are the air intake and exhaust louver systems, generator exhaust, influent control assembly and pump operations. Noise control worksheets shall be completed and submitted for review documenting noise control design data and calculations.
Twenty-four-hour ambient sound level recordings shall be specified to be made at the site prior to starting construction to document existing noise levels, and following construction when the station is operating. (28-ME-DG-02 § 20)