ARTICLE VI.
ENVIRONMENTAL PERFORMANCE STANDARDS.
ENVIRONMENTAL PERFORMANCE STANDARDS.
The following definitions are applicable to the environmental performance standards in this article:
(1) A-WEIGHTED SOUND LEVEL means the sound pressure level in decibels as measured on a sound level meter using the A-weighing network. The level so read is designated dB(A) or dBA.
(2) BACKGROUND NOISE means noise from all sources other than that under specific consideration including traffic operating on public thoroughfares, and is established by measuring the noise level over an eight-minute period of time.
(3) BOUNDING LOT LINE means the far side of any street, alley, stream or other permanently dedicated open space from the stationary source when such open space exists between the lot line of the stationary source and adjacent property. When no such open space exists, the common line between two parcels of property shall be interpreted as the bounding lot line.
(4) CONSTRUCTION means any phase of the on-site erection, including excavation, demolition, alteration, or repair, of any building or structure which is designed to be used on that site.
(5) DAYTIME means the hours between 7:00 a.m. and 10:00 p.m. on any given day.
(6) DECIBEL (dB) means a unit for measuring the volume of a sound, equal to 20 times the logarithm to the base 10 of the ratio of the pressure of the sound measured to the reference pressure, which is 20 micropascals (20 Micronewtons per square meter).
(7) EQUIVALENT SOUND PRESSURE LEVEL (Leg) means the time weighted, mean square, A-weighted sound pressure level.
(7.1) LEGAL HOLIDAY means New Year’s Day (January 1), Memorial Day (observed date), Fourth of July (July 4), Labor Day (observed date), Thanksgiving Day (observed date), and Christmas Day (December 25).
(8) MOBILE SOURCE means sound pressure created by motorized vehicles designed to operate on public rights-of-way, including, but not limited to, automobiles and aircraft.
(9) NOISE means any sound which annoys or disturbs humans or which causes or tends to cause an adverse psychological or physiological effect on humans.
(10) NOISE DISTURBANCE means any sound which (a) endangers or injures the safety or health of humans or animals, or (b) annoys or disturbs a reasonable person of normal sensitivities, or (c) endangers or injures personal or real property.
(11) PERMISSIBLE SOUND PRESSURE LEVEL means the equivalent sound pressure level (Leg) averaged over an eight-minute period of time.
(12) PERSON means any individual, association, partnership, or corporation, and includes any officer, employee, department, agency, or instrumentality of a state or any political subdivision of a state.
(13) PROPERTY means all contiguous land and any fixed or moveable object on such land, under common ownership, irrespective of leasehold or other interest.
(14) RETAIL DISTRICTS means the NS, SC, and GR districts.
(15) SOUND means the weighted sound pressure level obtained by the use of a sound level meter and frequency weighting network, such as A, B, or C, as specified in American National Standards Institute specifications for sound level meters (ANSI S1.4-1971, or the latest approved revision thereof). If the frequency weighting employed is not indicated, the A-weighting shall apply.
(16) SOUND LEVEL METER means an instrument which includes a microphone, amplifier, RMS detector, integrator or time averager, output meter, and weighting networks used to measure sound pressure levels.
(17) SOUND PRESSURE means the instantaneous difference between the actual pressure and the average or barometric pressure at a given point in space, as produced by sound energy.
(19) SPECIAL EVENTS means all public and private school related activities and all events where a special events permit is issued by the city of Dallas.
(20) STATIONARY SOURCE means the point of origin of any noise emitted from a property. Multiple sources on a property shall be treated as a single source.
(21) TIME WEIGHTED means an established period of time during which the sound pressure levels are averaged. (Ord. Nos. 17501; 18849; 19995; 29424)
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(a) General provisions.
(1) A person may not conduct a use that creates a noise level that exceeds the levels established in Subsections (b) through (e) or that exceeds the background level by five dB(A), whichever is greater.
(2) A sound level meter that meets the standards of the American Standards Association must be used to determine whether the level of noise violates this section. The instrument must be maintained in good working order. A calibration check should be made prior to and following any noise investigation.
(3) Traffic, aircraft, and other background noises are not considered in measuring noise levels except when the background noise level is being determined.
(4) For purposes of this section, any identifiable portion of a planned development (PD) district governed by a distinct set of use regulations is considered to be a separate zoning district. If the PD district or a portion of the district is limited to uses permitted in an expressly stated zoning district, the PD district or portion of the district is considered to be that zoning district; otherwise it is considered to be:
(A) an MF-3 zoning district if it is restricted to residential uses and those nonresidential uses permitted in a residential district; otherwise
(B) an I-3 zoning district if it allows one or more uses that are only permitted in that district; otherwise
(C) an I-2 zoning district if it allows one or more uses that are only permitted in an LC, HC, or industrial district; otherwise
(D) if it does not fit into one of the above categories, a GR district.
(5) The requirements of this section do not apply to:
(A) mobile sources;
(B) construction/demolition activities regulated by Chapter 30;
(C) special events for which a special events permit is issued under Chapter 42A;
(D) sound generating equipment or apparatus to warn the public of an emergency or for public safety;
(E) noise from use-related loading/unloading operations that impact residential areas when conducted during daytime hours; or
(F) the following activities, as long as they are conducted between the hours of 7:00 a.m. and 10:00 p.m., Monday through Friday, and between the hours of 8:00 a.m. and 7:00 p.m. on Saturday, Sunday, and legal holidays as a normal function of a permitted use and the equipment is maintained in proper working condition:
(i) Lawn maintenance.
(ii) Repair of personal use vehicles.
(iii) Home repair of place of residence.
(b) Permissible sound pressure level in residential districts. In a residential district, a person may not conduct a use so as to create a sound pressure level on the bounding lot line that exceeds the decibel limits contained in the following table:
Maximum Permissible Daytime Decibel Limits at the Bounding Lot Line of a Residential District | |
A Scale | |
Decibel Limit (dBA re 0.0002 Microbar) | 56 |
(c) Permissible sound pressure level in office, retail, and P districts.
(1) In an office, retail, or P district, a person may not conduct a use so as to create a sound pressure level on the bounding lot line that exceeds the decibel limits contained in the following table:
Maximum Permissible Daytime Decibel Limits at the Bounding Lot Line of an Office, Retail, or P District | |
A Scale | |
Decibel Limit (dBA re 0.0002 Microbar) | 63 |
(2) The sound pressure level at the boundary line between a residential district, as defined both in this chapter and in Chapter 51A, and an office, retail, or P district may not exceed the decibel limits specified in Subsection (b).
(d) Permissible sound pressure level in LC, HC, I-1, and I-2 districts.
(1) In an LC, HC, I-1, or I-2 district, a person may not conduct a use so as to create a sound pressure level on the bounding lot line that exceeds the decibel limits contained in the following table:
Maximum Permissible Daytime Decibel Limits at the Bounding Lot Line of a Use in an LC, HC, I-1, or I-2 District | |
A Scale | |
Decibel Limit (dBA re 0.0002 Microbar) | 65 |
(2) The sound pressure level at the boundary line between a residential district, as defined both in this chapter and in Chapter 51A, and an LC, HC, I-1, or I-2 district may not exceed the decibel limits specified in Subsection (b)(1).
(3) The sound pressure level at the boundary line between an office, retail, mixed use, multiple commercial, or parking district, as defined both in this chapter and in Chapter 51A, and an LC, HC, I-1, or I-2 district may not exceed the decibel limits specified in Subsection (c)(1).
(e) Permissible sound pressure level in an I-3 district.
(1) In an I-3 district, a person may not conduct a use so as to create a sound pressure on the bounding lot line that exceeds the decibel limits contained in the following table:
Maximum Permissible Daytime Decibel Limits at the Bounding Lot Line of a Use in the I-3 District | |
A Scale | |
Decibel Limit (dBA re 0.0002 Microbar) | 70 |
(2) The sound pressure level at the boundary line between a residential district, as defined both in this chapter and in Chapter 51A, and an I-3 district may not exceed the decibel limits specified in Subsection (b)(1).
(3) The sound pressure level at the boundary line between an office, retail, mixed use, multiple commercial, or parking district, as defined both in this chapter and in Chapter 51A, and an I-3 district may not exceed the decibel limits specified in Subsection (c)(1).
(4) The sound pressure level at the boundary line between an LC, HC, CS, LI, IR, I-1, or I-2 district and an I-3 district may not exceed the decibel limits specified in Subsection (d)(1).
(f) Noise level adjustments.
(1) The maximum permissible noise levels contained in Subsections (b)(1), (c)(1), (d)(1), and (e)(1) are subject to the following adjustments:
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Noise is present at nighttime . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Subtract 7db
Noise is impulsive (meter reading changes
at a rate greater than 10 decibels per second). . . . . . . . . . . . . . . . . . . Subtract 7db
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Noise has an “On Time” of no more than: | And an “Off Time” between successive “On Times” of at least: | ||
0.5 Minutes | 1/2 | Hour/ | |
5.0 Minutes | 1 | Hour/ | Add 10 Decibels to permitted level |
10.0 Minutes | 2 | Hours/ | |
20.0 Minutes | 4 | Hours/ | |
(2) “Off-time” is when the level of the primary noise being measured does not exceed that of the background noise by more than five dB(A). (Ord. Nos. 17501; 19455; 19786; 19995; 29424; 30895)
(a) In an I-1 or I-2 district, a person may not conduct a use so as to create earthborn vibrations on the bounding lot line that exceed the displacement contained in the following table:
Allowable Displacement of Earthborn Vibrations in I-1 or I-2 District | |
Frequency in Cycles per Second
| Displacement in Inches
|
0 to 10 | 0.0010 |
10 to 20 | 0.0008 |
20 to 30 | 0.0005 |
30 to 40 | 0.0004 |
40 and over | 0.0003 |
(b) In a I-3 district, a person may not conduct a use so as to create earthborn vibrations on the bounding lot line that exceed the displacement contained in the following table:
Allowable Displacement of Earthborn Vibrations in I-3 District | |
Frequency in Cycles per Second
| Displacement in Inches
|
0 to 10 | 0.0020 |
10 to 20 | 0.0016 |
20 to 30 | 0.0010 |
30 to 40 | 0.0006 |
40 and over | 0.0005 |
(Ord. 19995)
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