It is recommended that the definitions of technical terms used in the performance standards be listed in the section in which the terms are used; thus they are as follows:
(A) Noise.
AMERICAN NATIONAL STANDARDS INSTITUTE, INC. A national organization dedicated to the promulgation of the authoritative standards in many technical fields.
dB(A). Decibels as read on the sound level meter when set for the A-weighted filter. The A-weighted filter approximates the sensitivity of the human ear as to frequency response.
DECIBEL (dB). A unit which describes the sound pressure level or intensity of sound. A sound level meter is calibrated in decimals.
IMPACT NOISE. A short duration sound such as those from a foregoing hammer or punch press.
OCTAVE BAND. A prescribed interval of sound frequencies which classifies sound according to its pitch.
PREFERRED FREQUENCY OCTAVE BANDS. A standardized series of octave bands prescribed by the American Standards Association in S1.6-1960, Preferred Frequencies for Acoustical Measurements.
SOUND LEVEL METER. An electronic instrument which includes a microphone, an amplifier and an output meter which measures noise and the sound pressure levels in a specified manner. It may be used with the octave band analyzer that permits measuring the sound pressure level in discrete octave bands.
SOUND PRESSURE LEVEL. The intensity of a sound measured in decibels, mathematically described as 20 times the logarithm to the base 10 of the ratio of the pressure of the sound to a reference pressure of 0.0002 microbar.
(B) Vibration.
THREE-COMPONENT RECORDING SYSTEM. A complement of instruments or seismograph which can record simultaneously vibrating vectors in three mutually-perpendicular directions.
VIBRATION. The periodic displacement or oscillation of the earth.
(C) Smoke and particulate matter.
PARTICULATE MATTER. Material other than water which is suspended in or discharged into the atmosphere in a finely divided form as a liquid or solid.
RINGELMANN NUMBER. The shade of smoke as it appears on the Standard Ringelmann Chart published by the U.S. Bureau of Mines Information Circular No. 8333 (1967).
SMOKE. Small gas-borne particles other than water that form a visible plume in the air.
(D) Odor.
ODOR THRESHOLD. The lowest concentration of odorous matter in air that will produce an olfactory response in a human being.
(E) Toxic matter.
THRESHOLD LIMIT VALUE. The maximum allowable airborne concentration of a toxic material, as established by the American Conference of Governmental Industrial Hygienists.
TOXIC MATTER. Materials which are capable of causing injury to living organisms by chemical means when present in relatively small amounts.
(F) Fire and explosive hazards.
ACTIVE TO INTENSE BURNING. A rate of combustion described by material that burns with a high degree of activity and is consumed rapidly. Examples include sawdust, powdered magnesium, pyroxylin and other solids deemed by the Fire Department to have equivalent burning characteristics.
DETONABLE MATERIALS. Materials which decompose by detonation. Such materials include explosives, unstable compounds and fissionable matter.
FLASHPOINT. The lowest temperature at which a flammable liquid will momentarily burn under prescribed conditions. The closed cup flash point shall be authoritative and the test shall be run in accordance with the appropriate ASTM procedure.
SCF. Standard cubic feet, which is the measure of the volume of a gas reduced to 14.73 pounds per square inch pressure absolute and 60°F.
(G) Glare.
FOOT CANDLE. A unit of illumination. Technically, the illumination at all points one-foot distance from a uniform point source of one candle power.
(H) Noise. Noise shall be measured at any adjacent lot line and/or district boundary, as indicated in Table 1. At the specified points of measurement, the sound pressure level of any activity or operation (except those not under direct control of the industrial use, such as transportation facilities) shall not exceed the values tabulated in Tables 1, 2, 3 and 4 between the hours of 7:00 a.m. and 7:00 p.m. The instruments used for these measurements shall conform to all current and American National Standards Institute specifications. Impact noises shall be measured by means of an impact noise analyzer. Impact noises are those whose peak values are more than 3 dB higher on the fast response than the r.m.s. values indicated on the sound level meter.
(1) Table 1.
TABLE 1 | |||
Manufacturing District | Adjacent Lot Line | Commercial District Boundary | Residential District Boundary |
M-1 | A | B | C |
Between the hours of 7:00 p.m. and 7:00 a.m. the permissible sound levels across residential district boundaries shall be reduced by 5 dB in each octave band, or in the overall band for impact noise. | |||
(2) Table 2.
TABLE 2 MAXIMUM PERMITTED SOUND LEVELS, PREFERRED FREQUENCY OCTAVE BAND, DECIBELS | |||
Preferred Center Frequency, Cycles/Second | A | B | C |
31.5 | 88 | 86 | 83 |
63 | 79 | 75 | 71 |
125 | 69 | 64 | 59 |
TABLE 2 MAXIMUM PERMITTED SOUND LEVELS, PREFERRED FREQUENCY OCTAVE BAND, DECIBELS | |||
Preferred Center Frequency, Cycles/Second | A | B | C |
250 | 62 | 57 | 52 |
500 | 58 | 53 | 47 |
1,000 | 54 | 49 | 44 |
2,000 | 51 | 46 | 40 |
4,000 | 49 | 44 | 37 |
8,000 | 47 | 41 | 35 |
Measurement of the sounds levels may also be made by using a weighted scale sound level meter. The levels in Table 2 shall be considered to have been met if the weighted levels are no greater than the following:
(3) Table 3.
TABLE 3 MAXIMUM PERMITTED SOUND LEVELS, dB(A), FOR SCREENING PURPOSES | |
Required Level | Sound Level, dB(A) |
A | 60 |
B | 55 |
C | 50 |
(4) Table 4.
TABLE 4 | |||
Manufacturing District | Adjacent Lot Line | Commercial District Boundary | Residential District Boundary |
M-1 | A | B | C |
(5) Table 5.
(a) Particle velocity as specified below may be measured directly, or if computed on the basis of displacement and frequency, measurements shall be computed from the formula 6.28D, where F is the frequency of the vibration in cycles per second and D is the single amplitude displacement of the vibration in inches.
(b) The maximum permissible particle velocity of the ground vibration specified above shall be:
TABLE 5 PARTICLE VELOCITY | ||
Applicable Limit | Steady State, Inches/Second | Impact Inches/Second |
A | 0.10 | 0.20 |
B | 0.02 | 0.04 |
(c) The maximum particle velocity shall be the vector sum of three simultaneous mutually perpendicular components.
(d) For the purpose of this subchapter, STEADY STATE VIBRATIONS are vibrations which are continuous, or vibrations in discrete impulses more frequent than 100 per minute. Discrete impulses which do not exceed 100 per minute shall be considered impact vibrations.
(1983 Code, § 9-9-2) (Ord. 09-07, passed 9-8-2009)