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"Good Neighbors Keep Their Noise to Themselves"

St. Mary's County, MD Noise Ordinance
(NPC posted this April 2004)

St. Mary's County Comprehensive Zoning Ordinance


61.1 Specific Purposes and Applicability.
61.2 Exceptions to Height Limits.
61.3 Lighting Standards.
61.4 Noise Standards.
61.5 Refuse Storage Areas.
61.6 Screening of Mechanical Equipment.
61.7 Yards Requirement.
61.8 Site Access Criteria.

61.1. Specific Purposes and Applicability.

This chapter contains supplemental land use and use-specific site development requirements that are applicable to development in all zoning districts and for all use categories except for single-family detached dwellings, unless otherwise stated. References to buffer yards are to the types and specifications established in Schedule 63.4.3,, Landscaping and Buffer Yards.

61.2. Exceptions to Height Limits.

Except for height limitations imposed in the AICUZ/AE overlay districts in Article 4, height limitations of this Ordinance shall not apply to:

Public monuments Chimneys Standpipes Cooling towers
Commercial television antenna Belfries Conveyors Smoke stacks
Stage towers or scenery lots Church spires Water towers Elevator bulkheads
Ornamental towers and spires Silos Water tanks Flag poles
Commercial public radio antenna Fire towers Public communication towers, Public communication Antenna

61.3. Lighting Standards.

1. General Requirements. Exterior lighting will be evaluated in the site plan review process to ensure that functional and security needs of the project are met in a way that does not adversely affect adjacent properties or neighborhoods. The degree to which exterior night lighting affects the project, and adjacent properties or the neighborhood will be evaluated considering the light source, level of illumination, hours of illumination, and need for illumination.
a. Maximum on-site lighting levels must not exceed 10 foot-candles, except for loading and unloading platforms where the maximum lighting level must not exceed 20 foot-candles.
b. Light levels measured at any property line shall be measured at a height of six feet and not cause illnmination in excess of 0.5 foot-candle above the background level present when all on-site lights are turned off.
c. Light levels measured one foot above any exterior light fixture shall not cause illumination in excess of 0.5-foot candle above the background level present when all onsite lights are turned off.
d. Light levels measured three feet to the side (toward the nearest property line) and even with the bottom of any exterior light fixture shall not cause illumination in excess of 0.5 foot-candles above the background level present when all on-site lights are turned off.
2. Design Standards. The proposed lighting must also comply with the following design standards:
a. Site lighting that may be confused with warning, emergency or traffic signals is prohibited.
b. Areas, such as parking lots, must be illuminated as unobtrusively as possible to meet the functional needs of safe circulation and protecting people and property. Areas, such as building entrances and plaza seating areas must use local lighting that defines the space without glare.
c. Light sources must be concealed or shielded to the maximum extent feasible to minimize the potential for glare and unnecessary diffusion on adjacent properties and to eliminate to the maximum extent possible illumination of the night sky.
d. Flickering or intense sources of light shall be controlled so as not to cause a nuisance across any lot lines.

61.4. Noise Standards.

1. Except for emergency service land uses, and in the event of loss of utility service, no use shall create ambient noise levels that exceed the following standards:
Zone of Property Receiving Noise Maximum Noise Level Ldn or CNEL, dB
Residential Districts:RL, RH, RMX, and RNC 60
Commercial and Mixed Use Districts: CC, DMX, CMX, TMX, VMX, RCL, and RSC 65
Office, Business Park: OBP 65
Industrial and Marine Districts: I, CM 70
Planned Development In accordance with base district
2. Duration and Timing. The noise standards above shall be modified as follows to account for the effects of time and duration on the impact of noise levels:
a. In residential districts, the noise standards shall be 5 dB lower between 10:00 p.m. and 7:00 a.m.
b. Noise that is produced for no more than a cumulative period of five minutes in any hour may exceed the standards above by 5 dB.
c. Noise that is produced for no more than a cumulative period of five minutes in any hour may exceed the standards above by 10 dB.
3. Acoustic Study. The Planning Director may require an acoustic study. The Planning Director may require an acoustic study for any proposed project that could have or create a noise exposure exceeding the standards above. For any study required, noise shall be measured with a sound level meter that meets the standards of the American National Standards Institute (ANSI Section S1.4-1979, Type 1 or Type 2). Noise levels shall be measured in decibels from the property line. The unit of measurement shal l be designated as dB. A calibration check shall be made of the instrument at the time any noise measurement is made.
4. Noise Attenuation Measures. The Planning Director may require the incorporation into a project of any noise attenuation measures deemed necessary to ensure that noise standards are not exceeded.

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