Industrial Zoning Standards

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Industrial Zoning Standards

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At the end of World War II an era of unprecedented industrial expansion opened in the United States. In their efforts to find suitable sites for new plants, industrialists soon found themselves faced with a great shortage of industrial land. By 1946 most of the land in cities and much of the land in the periphery of cities was zoned. And almost without exception industrial expansion was left with the dirty end of the zoning stick.

The problem was so serious that in 1950 six national organizations established an inter-group committee to do something about it. (They include the American Society of Civil Engineers, the American Institute of Planning, the Association of State Planning and Development Agencies, the American Railway Development Association, the American Industrial Development Council, and the Society of Industrial Realtors. Later, when the secretariat of ASPDA was established as a separate office, the American Society of Planning Officials joined the group.) The new group was named the National Industrial Zoning Committee (NIZC). The first action of NIZC was to prepare and issue a pamphlet, Principles of Industrial Zoning. The NIZC pamphlet contains 12 precepts to guide planning and zoning commissioners, professional planners, and city councilmen when they come to adopting or revising zoning ordinances. The pamphlet was printed in large quantity and was distributed widely through the efforts of the constituent members of the NIZC.

Principle six for the industrial zone reads as follows: "There is a need for a reclassification of industry based on modern manufacturing processes and the prevailing policy of plant construction so as to determine the desirability or lack of desirability for inclusion in a given area."

At the National Planning Conference of the American Society of Planning Officials, held in Pittsburgh in 1951, principle six was expanded in a paper delivered at one of the sessions.* In brief, the thesis of the paper was this: zoning ordinances generally attempt to classify industries by name. With the rapid changes in industrial processes, such classification quickly becomes obsolete, if the classification is meant to keep similar industries together in the conventional "light" and "heavy" industrial districts. It is not the name of an industry that determines whether it is more or less obnoxious (the original basis tor segregation) but is rather the external effects of the industrial operations.

Therefore, it was proposed that industries be classified and grouped solely on the basis of external effects. Zoning districts would be described by listing the measurable limits of noise, smoke, odor, vibration, glare, etc. that would be permitted for any industrial use in that particular district but the uses would not be listed by name.

By analogy to similar objective descriptions in building codes, these limiting measurements were called "performance standards."

The basic idea of leaving a group or industries unnamed and, instead, setting limits to the obnoxious effects they might create was essentially the purpose of a catchall provision that appeared quite widely in zoning ordinances — "Any other lawful use which is not obnoxious by reason of its creation of noise, odor, glare. dust, or excessive vibration." This phrase frequently was put at the end of the list of specific uses permitted in the least restricted industrial district. The refinement introduced by performance standards was to substitute objective measurements for the idea of "obnoxious." Then description by measurement is extended to all industrial districts.

In this report we discuss in general terms the progress thus far in the use of standards for the control of uses placed in industrial districts. The comments will be based on a detailed analysis of 11 zoning ordinances either adopted or proposed in cities throughout the United States that introduce this concept.

What was actually the first zoning ordinance to use a performance standard would probably be difficult to uncover. Certainly one of the earliest was the ordinance for Niagara Falls, New York (1951), prepared by Hugh Pomeroy. In this ordinance the uses permitted in the M-1 industrial zoning district were described as:

Any manufacturing or other industrial operation from which no dust, smoke, fumes, gas, noxious odor or other atmospheric effluence is disseminated beyond the boundaries of the M-1 district in which such use is located, and which produces no noise exceeding in intensity at the boundary of such M-1 district the average intensity of noise of street traffic at that point: ...

Another ordinance that introduced several new ideas in zoning was the proposed New York zoning resolution published in 1950. Although the New York proposal did not go all the way to a substitution of performance standards for lists, it was designed specifically with the idea that numerical standards could be easily introduced later as simple amendments.

The first two ordinances to attempt to use performance standards in the manner envisioned by the NIZC were the ordinances for Warren Charter Township, Wayne County, Michigan, and Parsippany-Troy Hills Township, Morris County, New Jersey. Warren Township is in the metropolitan Detroit area, and already contains quite a bit of industry. Parsippany-Troy Hills Township is primarily a residential area in the New York metropolitan region.

Several other ordinances have been written since the Warren and -Parsippany-Troy Hills ordinances but a quite significant step was taken by the city of Chicago in 1954. In that year the city (which was completely revising its zoning ordinance) appropriated $12,000 for research to establish appropriate standards. The contract was awarded to Armour Research Foundation, an affiliate of Illinois Institute of Technology. The proposals for control of industrial zoning districts were made public late in 1955.

There has been general endorsement of the theory of performance standards in zoning. At the same time there have been serious practical questions on administration. The questions have been directed toward these points:

l – What are reasonable standards?

2 – How can you tell prior to actual construction whether or not the plant, when it is built and operating, will comply with the standards?

3 – Can you train the ordinary building inspector to make the necessary and quite complex measurements used?

4 – How will you handle future violations by a plant that originally complied with all regulations?

5 – How will you handle existing uses that do not comply with new standards (uses nonconforming as to noise or smoke, etc.)?

The experience in administering performance standards zoning as of today is practically nil, so the final answers to these questions are not available. The best one can do is to try to discover, from the texts, how the writers of the zoning ordinances propose to answer these questions, if they do.

Effects Regulated

In Performance Standards in Industrial Zoning, 11 effects are discussed and the possibilities of establishing numerical standards for each of them briefly explored. With three exceptions — traffic, aesthetics, and psychological effects — each of these is included in one or more of the performance standards ordinances analyzed here. In addition to those effects listed in the 1951 discussion, three other sources of annoyance — vibration, electromagnetic interference, and radioactive emissions — are listed in some of the ordinances.

Table 1 shows a breakdown of the subjects covered in the performance standards ordinances to date. The table also distinguishes between those effects for which numerical standards are given and those which are completely prohibited. Of course, the complete prohibition of an emission can also be stated as placing a maximum of zero units (whatever the suitable unit might be) on the emission. However, in some cases complete prohibition has been used because the writer of the ordinance could not find satisfactory units of measurement or numerical standards for that particular effect.

TABLE 1. STANDARDS USED FOR INDUSTRIAL ZONES

KEY:

# – Numerical standards used

P – Included as a separate standard but numerical limits not used

* – Bulk sub-districts used to make a total of 11 different types of industrial zones

Number of Zones

One basic weakness of industrial zoning has been the use of the terms "light" and "heavy" industry. Planners could get together and agree that watch manufacturing was definitely "light" and blast furnaces definitely "heavy" but there was no agreement on the exact point at which "light" changed to "heavy." Besides, industries that might have been considered "heavy" ten years ago had changed their processes and cleaned up their operations until they were no more obnoxious than industries once classed as "light."

Table 2 shows, in an abbreviated version, the manner in which the various districts are differentiated from one another. Thus, the two industrial districts in the Parsippany-Troy Hills ordinance differ in these respects: in the second zone, plants are permitted to create more noise and more smoke and are required to have larger lots. All other regulations are the same for the two districts.

TABLE 2. DIFFERENTIATION BETWEEN ZONING DISTRICTS

In two ordinances, only one industrial district is established. In another, the standards apply to all zones —residential and commercial, as well as industrial. This raises a question on a fundamental point in zoning. Is the use of standards in these cases a proper function of a zoning ordinance? Or should this type of regulation be the subject of separate ordinances?

This is more than an academic question. There is evidence that some planners have seized on the idea of performance standards as an opportunity to introduce a type of regulation that has not previously been acceptable to the city council.

As an example: a zoning ordinance establishes Ringelmann No. 2 as the limit of permissible smoke in its industrial zone. This is a reasonable maximum for smoke for the entire city. But for one reason or another the city has not been able to adopt a general smoke abatement ordinance. so that in all other districts, residential and commercial, smoke can go to any density to Ringelmann No. 5, 100 per cent opaque, with no legal sanctions forthcoming. There are certainly temptations for the zealous planner to see performance standards as a vehicle by which he can introduce reforms that could not yet stand alone.

On the other hand, the planner may reason that smoke abatement must come some day to every city. It is much less expensive to build smoke control into the plant at the time it is originally constructed than it is to add the necessary equipment later.

The Administration of the Ordinance

It is believed that in large cities it will be relatively simple to employ inspectors with enough technical training and skill to make the rather complex measurements necessary to determine compliance with performance standards. In Chicago, for example, there is a department of smoke abatement with a trained inspection staff competent to carry out the very complicated measurements of particulate matter proposed in the new zoning ordinance.

But for smaller cities, the Chicago provisions will certainly look forbidding. To forestall anxiety concerning an ordinance he was preparing for Kettering, Ohio (population 28,000) Ladislas Segoe wrote:

A preliminary investigation made by us indicates that certain of the industrial research organizations in southern Ohio do consider themselves capable of performing the measurements and evaluations required by the proposed ordinance. Where such services are required, the cost of hiring the research firm is paid by the industry desiring to locate in the city.

The Parsippany-Troy Hills and Penn Township ordinances place the burden of proof on the applicant for proving that he will meet the standards. In these townships, all applications for industrial use occupancy permits are reviewed by the boards of adjustment.

An application for a Certificate of Occupancy for a building or land use in any Industrial Zone shall be accompanied by:

(1) A plot plan of the lot showing the location of all present and proposed buildings, drives, parking lots, waste disposal fields and other constructional features on the lot; and all buildings, streets, alleys, highways, streams and other topographical features outside of the lot and within 200 feet of any lot line;

(2) Architectural plans for any proposed buildings;

(3) A description of the industrial operations proposed in sufficient detail to indicate the effects of those operations in producing traffic congestion, noise, glare, air pollution, water pollution, fire hazards or safety hazards;

(4) Engineering and architectural plans for the treatment and disposal of sewage and industrial waste;

(5) Engineering and architectural plans for the handling of any excess traffic congestion, noise, glare, air pollution, water pollution, fire hazard or safety hazard;

(6) Designation of the fuel proposed to be used and any necessary architectural and engineering plans for controlling smoke;

(7) The proposed number of shifts to be worked and the maximum number of employees on each shift;

(8) Any other data or evidence that the Board of Adjustment may require. (Parsippany-Troy Hills)

These ordinances go further for certain industries. They recognize that it is unfair to judge the possible annoyance of a new plant by the annoyance created by the same kind of industry in an old plant operated somewhere else. At the same time, the governing body knows that just because it is possible to minimize noise, odor, smoke. etc., there is no certainty that the proper control devices will be installed. Therefore, the ordinances list groups or uses that have a reputation for unpleasant emissions and require applicants for these uses to submit detailed plans of their proposed control methods. But the ordinances go further and require a public hearing on an application so that the citizens can also be assured of the inoffensive nature of the proposed operation.

While it may be practical to call in outside experts to review original applications, it may not be so convenient to use such consultants for routine inspections after the plant is operating. The Parsippany-Troy Hills ordinance attempts to meet this problem by allowing the board of appeals to require automatic recording devices.

...Where appropriate, the Board may require the installation, maintenance and operation by the applicant of continuous recording instruments to demonstrate the operation or effect of operation of any machines or devices used to control or lessen noise, glare, air pollution, water pollution, fire hazards or safety hazards.

*****

The detailed analysis of the standards used in the 11 zoning ordinances follows below. Again, it should be emphasized that there has been practically no experience in administering these provisions. The analysis is based on the text of the ordinances, together with some experience in enforcing related ordinances, such as those for citywide noise abatement.

Noise

In all of the ordinances, noise is one of the effects mentioned, and in all but one, numerical standards limiting noise are given. In three ordinances, the unit of measurement is the sone. In all of the others, the unit used is the decibel. Only in the Chicago and Clarkstown ordinances is there a breakdown of intensity limits for different portions of the sound spectrum.

TABLE 3. STANDARDS FOR NOISE LIMITS

The sone is a unit of loudness, an explanation of which is beyond the scope of this report.** It does give a reasonably accurate measurement of the annoyance created by various sounds but it does not have general acceptance among acoustical scientists yet. Also, it cannot be measured directly by any instrument so that it does not lend itself to the establishment of a standard easily administered. However, we can probably say that the ordinances using sones to measure noise limits are reasonable.

The decibel is a measure of sound pressure. Low-pitched sounds are considerably less annoying than those of high pitch. Therefore, greater intensity of sound can be permitted in the low end of the noise spectrum than in the high end. There is no instrument available that automatically takes into account this subjective psychological characteristic of noise. The practical way to handle it at present is through the establishment of decibel limits for the sound levels at each of several frequencies. The only ordinances that thus far do set up various limitations for the several parts of the sound spectrum are those for Chicago and Clarkstown.

The Chicago ordinance establishes standards in terms of sound levels for the several audible s. Table 4 gives the standards proposed for Chicago. The ordinance does not differentiate among the five industrial zones as to permissible noise; there is one maximum.

TABLE 4. PROPOSED NOISE STANDARDS, CHICAGO AND CLARKSTOWN ZONING ORDINANCES

The Clarkstown ordinance establishes two sets of noise limits — one for noises between the hours of 7 a.m. and 10 p.m., the other for the hours between 10 p.m. and 7 a.m. Actually, the ordinance lists only the nighttime limits, allowing five decibels greater pressure for each octave band during the rest of the day.

The Chicago ordinance allows greater noise at business district boundaries than at residence district boundaries and, by inference, unlimited noise within the industrial districts themselves. This differentiation according to the use of adjacent property is carried into much more detail in the Rye ordinance, shown below, and in the Southfield ordinance, shown in the Appendix.

TABLE 5. PROPOSED NOISE STANDARDS, RYE ZONING ORDINANCE

A limitation on intensity alone does not guarantee that a noise will not annoy, since intermittence also annoys. This is handled in several ordinances by a provision similar to the following:

Objectionable noises, due to intermittence, beat frequency, or shrillness, shall be muffled so as not to become a nuisance to adjacent uses. (Southfield Township)

Requirements on instrument standards are used in the Chicago, Southfield Township, and Rye ordinances, while the latter two allow for temporary violations of the noise limits.

Sound levels shall be measured with a sound level meter and associated octave band filter manufactured according to standards prescribed by the American Standards Association. (Chicago)

The Clarkstown ordinance applies a correction factor for any "noise of impulsive character (hammering, etc.)" and for any "noise of periodic character (hum, screech, etc.)." The permissible limit for each octave band is reduced five decibels.

Comments: A noise limit specified only by a single decibel figure with no mention of octave bands, of instrument standards, or of a frequency weighting network is meaningless under strict interpretation. It is possible that a liberal court might read into the figures a proper adjustment. But in view of the quite precise nature of the term "decibel" this is doubtful.

The sone is also a clearly (although not easily) defined term and actually needs no further elaboration in the ordinance. However, because the sone is not directly measurable by simple instruments, it is not the most practical unit to describe noise.

The standards proposed for Chicago and Clarkstown are without doubt the most scientifically prepared of any to date. Consultants for the Chicago standards were scientists from Armour Research Foundation; for the Clarkstown standards the consultants were Bolt, Baranek and Newman, acoustical consulting firm. For a large city, where it is financially practical to use highly trained technicians, these two sets of standards are in the most usable form. This statement should also apply to the smaller city that intends to use consultants.

In general, it would seem that the use of the decibel unit of noise, specifying measurement by a standard weighted instrument, will be the easiest to understand and to administer. It is also quite probable that this type of limit and measurement will parallel the limits and instruments used in citywide noise abatement ordinances. Nevertheless, acoustical scientists are skeptical of the value of frequency-weighting as an effective method for measuring the disturbance created by noise. It is even possible that the American Standards Association will drop it from its instrument specifications.

A provision on intermittent noises seems to be an advisable safeguard.

The best location at which to take noise measurements and a variation of permissible limits according to adjacent uses are subjects on which we must await experience. A limit based on measurement at any property line is the simplest to write and to administer. It may not be as realistic or equitable as varying the limit according to the adjacent use. Setting no limit on noise within a district might lead to abuses difficult to correct, since any industry itself has a reciprocal right to protection from annoyance by its neighbors, no matter what they are.

This is an appropriate point to comment on one of the dangers in performance standards. Unless a standard is written with the help of a competent expert in the field, it is possible to incorporate incorrect — even ludicrous — provisions in the ordinance. For example, the following provision appears in one ordinance:

Method of Measurement: The sound level, in decibels, measured at the points adjacent to the various use districts shall meet the established levels ninety (90) per cent of the time, and shall at no time exceed the established sound levels by more than ten (10) per cent. The sound levels shall be measured with an approved standard sound-level meter incorporating a 40db frequency-weighing network, or by any method subsequently approved by the U.S. Bureau of Standards.

There are at least three errors in this provision: (1) To exceed a sound level by "10 per cent" is a peculiar concept. Does this mean that for a limit of 60 decibels, occasional noises up to 66 decibels will be permitted? If so, the additional 6 decibels represent an increase, not of 10 per cent, but of about 400 per cent in sound pressure. Ten per cent excess of sound pressure would permit approximately 60.3 decibels, an accuracy that is impractical for field measurements of noise. (2) The proper term is "frequency-weighting" not "frequency-weighing." (3) The U.S. Bureau of Standards establishes no standards for acoustical instruments. The proper organization is the American Standards Association. (The best specification for instruments is that in the Clarkstown ordinance.)

This is a serious problem. The improper use of one standard can cast discredit on the entire ordinance, leaving the city with less land use regulation than when there was no zoning.

Smoke

All ordinances except that for Penn Township establish numerical standards governing the emission of smoke. In every case the Ringelmann chart was specified as the measuring instrument. In the Southfield Township ordinance, the umbrascope was listed as an optional measuring device.

The limits vary from the requirement that only smokeless fuel be used, to a limitation of Ringelmann No. 3 (60 per cent density) as shown in Table 6. In line with customary smoke abatement standards, each ordinance also permits the maximum to be exceeded for short periods.

TABLE 6. SMOKE

Note: limits smoke in the C3 unlimited commercial districts to "10% blackness, as measured by the Ringelmann chart" and in the M1 and M2 industrial districts to "20% blackness as measured by the Ringelmann chart...up to 30% blackness...6 minutes in any hour": This is quite obviously an error, since the intervals between Ringelmann numbers are all 20 per cent and there is no way of measuring either 10 or 30 per cent densities with the chart.

As an example of a complete provision, the following is quoted:

Smoke: It shall be unlawful for a person, firm or corporation to permit the emission of any smoke from any source whatever to a density greater than that density described as No. 1 on the Ringlemann Chart; provided that the following exceptions shall be permitted: smoke, the shade or appearance of which is equal to but not darker than No. 2 of the Ringlemann Chart for a period, or periods, aggregating four minutes in any 30 minutes.

Method of Measurement: For the purpose of grading the density of smoke, the Ringlemann Chart, as published and used by the United States Bureau of Mines, which is hereby made a part of this Ordinance, shall be the standard. However, the Umbrascope readings of smoke densities may be used when correllated with Ringlemann's Chart. (Southfield Township)

Comments: Standards for limiting smoke emission have probably been the easiest of all to determine because of the extensive experience with smoke abatement ordinances. A simple measuring device has been developed and is readily available.

An important consideration in establishing smoke standards is whether the control is consistent with over-all municipal smoke control. Any mention of smoke was probably omitted from the Penn Township ordinance because of the excellent smoke abatement ordinance and administration for all of Allegheny County. No attempt has been made in this study to determine how the zoning standards fitted with the general smoke control ordinance, nor even whether there was general smoke control.

It can be claimed that setting limits on industrial smoke emission without similar limits for other uses is discriminatory. In answer, it can be said that eventually all municipalities will have strong smoke control programs and that it is more economical to introduce prevention at the time of new construction.

Dust and Dirt

Each of the 11 ordinances introduces a provision to limit dirt and dust emission. In three of them such emission is flatly prohibited. A typical provision limiting dust, dirt, and fly ash reads about as follows:

Shall not exceed .3 grains per cubic foot of flue gas at stack temperature of 500 degrees Fahrenheit, of which amount, not to exceed .2 of a grain per cubic foot shall be of such size as to be retained on a 325 mesh U.S. standard sieve. The conditions are to be conformed to when the percentage of excess air in the stack does not exceed 50 per cent at full load.

The provisions on smoke and particulate matter in the Chicago ordinance, however, are quite detailed, running to some seven and one-half pages in the mimeographed draft. The ordinance sets up a rather complicated method of calculating emission, including tables allowing for different heights, velocities, and temperatures of the emission. Then the limitation is stated in pounds of particulate matter per acre of lot area during any one hour. In the three manufacturing zones the limitations are 1 pound, 3 pounds, and 8 pounds, respectively.

For economy of space, the very elaborate Chicago provisions are reproduced only once, in the Appendix. These standards were established by scientists at Armour Research Foundation and undoubtedly represent the most careful approach to the problem of all the ordinance provisions on dust and dirt examined. To explain the reason for such detailed standards, we quote from the paper delivered by Jack Smith, senior planner with the Chicago Plan Commission, at the 1954 National Planning Conference.

Smoke, dust and other types of particulate matter. A third major field of concentrated research was smoke and particulate matter. We are considering smoke, dust, and other forms of solid and liquid particulate matter as falling under one interrelated system of standards. The emission of particulate matter results from the combustion of solid fuel, from wind-borne dust, and from industrial operations creating dust, sprays, mists, and other finely divided materials.

If only one type of pollution control were possible, this control should be imposed upon particulate matter. Particulate matter is a nuisance in the forms of cinders in the eyes, soot on shirt collars, dirt and dust on the furniture. Particulate matter is the major air pollution problem in Chicago. It is estimated that approximately 58 per cent of Chicago's monthly dust fall of 55 to 60 tons a square mile are from commercial and industrial sources. The average citywide dust fall is approximately 6 pounds an acre a day, while the average daily emission for an industrial acre is 50 pounds. Our performance standards contain these primary devices: (l) The Ringelmann Chart to limit the density of visible emissions. (2) Limits on the size of particulate matter. (The collection of particulate matter as large as 44 microns is now technologically feasible and relatively inexpensive.) (3) Limits on the total weight of particulate matter discharge for each acre of property area. (We feel that this is a much fairer method of regulating air pollution. The actual limits for the three industrial zones were established on the basis of the analysis of emission from various types of industrial operations and types of fuel burning equipment.) (4) Formulae for computing additional permitted discharge on the basis of (a) height of stack, (b) emission velocity, and (c) temperature of emission. These factors are important in assessing nuisance creation. For example, high stacks and high temperatures tend to cause the waste to travel greater distances and become quite dilute before reaching the ground.

It is quite probable that the provisions on particulate matter in the Chicago ordinance are the most equitable of any analyzed in this report. Again, however, measurement would not be easy, especially for small cities. The simple provisions from the other ordinances have much to recommend them. There is evidence that the writers of some of the other ordinances may have copied something about which they knew little and because of this lack of knowledge the results are garbled. The provisions that refer to standardized methods of measurement are likely to be the most satisfactory to administer.

Odor

The control of odor is provided for in each ordinance. In no ordinance are numerical standards given directly but the Clarkstown ordinance does include numerical measurements by reference. The Clarkstown provision is the most complete regulation of odors in any of the 11 ordinances.

Odors. No emission of odorous gases or other odorous matter in such quantities as to be offensive at the specified points of measurement. Any process which may involve the creation or emission of any odors shall be provided with a secondary safeguard system, so that control will be maintained if the primary safeguard system should fail. There is hereby established as a guide in determining such quantities of offensive odors Table III (Odor Thresholds) in Chapter 5 "Air Pollution Abatement Manual" copyright 1951 by Manufacturing Chemists' Association. Inc., Washington, D.C.

The provision in the Anne Arundel County ordinance is typical of the other ordinances. Any use shall "emit no objectionable odors outside the lot lines of the tract."

The Rye ordinance contains a brief description of measurement or odor:

Method of Measurement: A noxious concentration shall be deemed to be the point at which the measurement of the threshold of smell can be achieved, and shall be measured in ounces per thousand cubic feet of air.

The Southfield Township ordinance contains a similar provision on measurement.

Comments: While the complete prohibition of the emission of substances with unpleasant odors may have been the purpose of some of these ordinances, at least some of the provisions were included as temporary controls. There are still no simple and accurate methods for odor measurement. Even a substance of unpleasant odor is harmless in an olfactory sense until it reaches the concentration necessary to pass the threshold of smell. For this reason, complete prohibition is not too logical. Nevertheless, fully satisfactory odor standards are not yet available. The Clarkstown provision refers to Table III, Chapter 5 of the Air Pollution Abatement Manual. While this is probably one of the best compilations of odor thresholds, it is also ambiguous. Four authorities are cited in the table for the odor threshold of hydrogen sulfide and the figures range from 0.025 to 1.0 parts per million (p.p.m.). Six concentrations are given for pyridine from 0.00032 to 10.0 p.p.m. If the table is referred to, the particular value to be used — such as the smallest — should also be indicated.

Toxic Gases

Most of the ordinances contain provisions on toxic gases. As with odors, the provision is merely a prohibition against emission, with one exception. The Penn Township provision is typical of the prohibiting clause: "All industrial uses shall...emit no noxious, toxic or corrosive fumes or gases."

The Center Line ordinance establishes definite standards for certain dangerous gases:

Gases as measured at property line. [Sulfur dioxide] gas shall not exceed an average of .3 p.p.m. over a twenty-four (24) hour period, provided, however, a maximum concentration of .5 p.p.m. will be allowed for a one (1) hour period out of a twenty-four (24) hour period. Hydrogen sulfide shall not exceed .l p.p.m.; Flourine shall not exceed .l p.p.m.; Nitrous fumes shall not exceed 5 p.p.m. [Carbon monoxide] shall not exceed 15 p.p.m.

Comments: Allowable limits for toxic gases present some difficult problems. If, for example, we take sulfur dioxide, one of the gases mentioned in the Center Line ordinance, we find the following limits in the Air Pollution Abatement Manual of the Manufacturing Chemists' Association:

The concentration allowed by the Center Line ordinance is well below all criteria except that for vegetation injury.

Of the limits quoted above, the one most important to human health is the first — Maximum Allowable Concentration (MAC). This limit was established for conditions under which industrial employees work. As shown, it is the danger point for exposure eight out of each 24 hours and five out of each seven days. No determination has yet been made of a maximum allowable concentration for 24 hours a day, 7 days a week, which is the exposure that neighbors might get from industrial emissions. In the example of sulfur dioxide, the MAC is substantially greater than the Center Line zoning ordinance permits. But it will be noted that the concentration injurious to vegetation likewise is for an attenuated period, seven hours, and the Center Line limit is only very slightly below the injurious concentration. The ordinance also permits a greater concentration for a shorter period, the effects of which on vegetation have not been determined.

The Center Line ordinance establishes standards for five toxic gases (considering "nitrous fumes" as one gas). The Air Pollution Abatement Manual lists the MAC for 116 "gases and vapors" and 27 chemical "dusts, fumes, and mists." Among these are many harmful pollutants that have been found and measured in urban atmospheres, such as fluorides, beryllium, copper, lead, and zinc — not mentioned in the Center Line ordinance.

These comments are not intended as a destructive criticism of the Center Line provision. Rather they are meant as a discussion of the extreme difficulty of this particular problem. Air pollution experts are not at all agreed on the acceptable limits in this field of toxic gases, although there is complete agreement that controls and limits must be sought.

Here again we have the question, "Do limits on toxic gases belong in a zoning ordinance?" Once a safe maximum is established, it certainly should not be different in different districts. Since toxic gases are so directly connected with human health and safety, it is not logical to permit continuance of a "legal nonconforming use" that is nonconforming because of its emission of toxic gases in excess of the allowable limit.

A final comment should be made on the administration of a provision on toxic gases. The detection of toxic gases is not easy but it can be done with proper equipment. However, reliable measurements of the quantity of the pollutant are quite difficult to make.

In the present state of knowledge on toxic air pollutants. it would seem that the best provision in a zoning ordinance would be complete prohibition. Perhaps reference could be made to "Table I, Industrial Hygiene Standards, Maximum Allowable Concentration," Chapter 5 of the Air Pollution Abatement Manual, for a list of toxic pollutants to be prohibited but the values for MAC should not be taken as standards for the ordinance. Here again, however, there is a chance for a claim of unreasonableness. The table lists carbon monoxide, a clearly dangerous gas but one that is extremely difficult to eliminate completely. It is apparently reasonably harmless in concentrations that are substantially below the MAC and, most important, is one that is emitted in much greater quantity, with no controls, by motor vehicles.

Glare and Heat

Provisions on glare and heat are contained in seven ordinances but in none of them are there any numerical standards. A typical provision is that for Warren Township:

Glare and heat from arc welding, acetylene torch cutting or similar processes shall be performed so as not to be seen from any point beyond the outside of the property.

The Clarkstown ordinance contains a different wording, one which would undoubtedly exclude Bessemer converters:

Glare. No direct or sky-reflected glare, whether from floodlights or from high temperature processes such as combustion or welding or otherwise, so as to be visible at the specified points of measurement. This restriction shall not apply to signs otherwise permitted by the regulations.

The Penn Township ordinance is somewhat more general:

...all industrial, uses shall...carry on no operation that would produce heat or glare beyond the property line of the lot on which the industrial operation is located;

The Parsippany-Troy Hills and Penn Township ordinances also contain provisions on industrial lighting:

...all industrial uses shall...use industrial and exterior lighting in a manner that produces no glare on public highways and neighboring property;

Comments: There are available adequate units for the measurement of heat (degrees of temperature, calories, B.T.U.) and glare (foot-candles). At the same time, it would seem unnecessary to complicate the zoning ordinance with standards expressed in such units. Prohibition in the simple terms of the quoted provisions is probably entirely satisfactory.

Industrial Sewage Waste

In four ordinances, numerical standards governing industrial wastes are established. In two others, Anne Arundel County and Penn Township, industrial sewage standards are incorporated by reference to the state department of health.

...the written approval of the appropriate Official of the Water Pollution Control Commission and the state Department of Health [shall] be filed with the Zoning Official regarding compliance with their requirements or stream pollution prevention, prior to requesting a building permit or certificate of occupancy for an industrial use. (Anne Arundel County)

The four ordinances with numerical standards are those for Parsippany-Troy Hills, Rye, Southfield Township, and Warren Township. To save space, the provisions are omitted from this section of the report and will be found in the Appendix. The Rye ordinance, which is not included in the Appendix, uses the same standards for industrial wastes as those for Southfield Township.

The standards for industrial waste are those commonly used in sanitary engineering and stream pollution control, One different provision is introduced in the Parsippany-Troy Hills ordinance, which provides that the maximum quantity of effluent shall not exceed 10 per cent of the minimum daily stream flow.

Comments: Jack Smith, in speaking of the consideration of industrial waste in the Chicago ordinance, said:

The analysis of industrial waste disposal as related to industrial plant location in Chicago resulted in the conclusion that this problem was handled adequately by the sanitary district on an individual plant "custom" basis. Therefore, additional zoning controls are considered unnecessary. However, this happy situation probably does not exist in most areas. Fortunately, the basic information is available for writing industrial waste standards for cities needing this control.

The need for industrial waste standards is somewhat different from the need for any of the other standards. In Performance Standards in Industrial Zoning it was described as follows:

A municipal sewerage system is, or should be if it isn't, planned for a long time in the future. In some rare instances it may be possible to expand the system — laterals, mains, interceptors, disposal works — easily for any part of the city. But in the majority of cities, the sewerage system is a miscellany of sections, some of which can handle more sewage than they are taking, others that are up to or over capacity, still other sections that cannot be expanded economically. So it is quite important that we plan our industrial areas with the present and potential sewerage system in mind.

Industrial sewage differs from the other subjects covered thus far, in that it is not necessarily a nuisance. Of course, industrial waste discharged raw into a stream can be a nuisance. However, it is assumed that state and local health laws are effective in preventing this. If they are not, the zoning ordinance cannot be a satisfactory substitute. Delineating industrial zones based on the capacity of the sewerage system is primarily a land planning problem. Still, the principal tool for carrying out the land plan is the zoning ordinance. Industrial sewage standards should be in it.

An analysis of these several ordinances would indicate that the industrial waste standards were primarily directed toward the prevention of stream pollution, perhaps with the idea of establishing higher standards than those of the state department of health. Or perhaps the standards are inserted in the zoning ordinance to give the local government the power to act quickly and directly to avoid prolonged abuse.

Smith's remarks on the Chicago experience show that the zoning study commission in that city used the other approach, i.e., a study of the capacity of the municipal sewerage system to handle wastes in different parts of the system.

Several of these ordinances have been written presumably for areas as yet undeveloped industrially (for example, Anne Arundel County). The sewerage system is also relatively undeveloped. Probably the writer of this zoning text assumed that there is not yet any limit to the capacity of a system that might be built. It is not yet necessary to make rules to limit sewage discharge on a density basis.

There is little to say either way about the adequacy of the industrial waste standards in ordinances. However, provisions relating the capacity of an existing sewer system to a specific area within a community have yet to be written.

Vibration

"Excessive vibration" is more often than not one of the manifestations forbidden in industrial districts. It appears in five of the ordinances reviewed here.

The proposed Chicago ordinance does not establish objective measurements but it does provide differentiation:

M1 and M2 districts:

...any use creating intense earth-shaking vibration shall be set back at least five hundred feet from the lot lines on all sides, except for lot lines adjoining an M3 District where such setback shall not be required, but in no case shall any such vibration be perceptible along the boundary line of atty other zoning district except M3.

M3 districts:

Any use creating intense earth-shaking vibrations shall be set back at least five hundred feet from the boundary of a Residence, Business, Commercial, M1 or M2 District, but in no case shall any such vibration be perceptible along the boundary of any other zoning district.

An ordinance that contains a numerical limit on vibration is the one for Center Line:

Machines or operations which cause vibration shall be permitted, but no operation shall cause a displacement exceeding .003 of one (1) inch as measured at the property line.

As originally written, the Clarkstown ordinance contained the following provision on vibration:

Vibration. No vibration which is discernible to the human sense of feeling for three minutes or more duration in any one hour of the day between the hours of 7 a.m. and 7 p.m., or of 30 seconds or more duration in any one hour between the hours of 7 p.m. and 7 a.m. No vibration at any time shall produce an acceleration of more than 0.l g or shall result in any combination of amplitudes and frequencies beyond the "safe" range of Table 7, U.S. Bureau of Mines Bulletin No. 442, "Seismic Effects of Quarry Blasting," on any structure. The methods and equations of said Bulletin No. 442 shall be used to compute all values for the enforcement of this Sec.

Before the ordinance was adopted, the first sentence ("No vibration...7 p.m. and 7 a.m.") was deleted because it was felt that discretion would be involved in interpreting the word "discernible."

Comments: If the displacement maximum specified in the Center Line ordinance is equitable, that provision may be the proper approach. The prohibition of large punch presses, etc., by name has been used as a temporary expedient. The Chicago proposal might be reasonable, if one could be sure at what point "earth-shaking" vibrations became "intense" enough to call for the 500-foot setback. The Clarkstown regulation, as amended, would probably prohibit only blasting operations.

Fire and Safety

Standards to reduce fire and safety hazards, while considerably short of the ideal of objective measurement, are improved over the provisions in pre-World War II ordinances. They are customarily tied in with building or fire safety codes.

By far the most complete provision against fire and safety hazard is found in the Chicago ordinance. The Chicago provisions, in brief, are as follows:

M1 districts:

1 – Incombustible to moderate burning materials — permitted freely.

2 – Free or active burning to intense burning materials

(a) enclosed within incombustible walls

(b) 40-foot setback or automatic sprinkler.

3 – Flammable vapors at ordinary temperatures — prohibited.

M2 districts

1 – Free to active burning materials

(a) enclosed within incombustible walls

(b) protected by automatic sprinkler.

2 – Flammable vapors at ordinary temperatures prohibited.

M3 districts:

1 – Fast burning materials.

2 – Flammable vapors at ordinary temperatures permitted except within 600 feet of any other district.

Several of the ordinances include detailed standards regarding the storage of materials, particularly of flammable materials. These are directed for the most part to fire and safety protection.

Comments: The Chicago provisions were prepared with the help of Armour Research Institute fire hazard experts. This group of men has long had a high reputation in the field. If there is a clear method for classifying materials by steps from incombustible to intense burning, the provisions present no particular problems of interpretation or enforcement. Whether they are suitable as they stand for smaller cities may be questionable, so that verbatim copying should be avoided. However, they seem to be a satisfactory form for measuring this hazard. Additional standards on storage maybe desirable. It would also seem desirable to specify fireproof construction tor all buildings in the district if the building code does not do so.

Electromagnetic Interference

One reason for drafting the technical education research district in Southfield Township was to establish a district in which electronic laboratories could locate with assurance that they would be free from outside electromagnetic interference. These standards are quite complex and are undoubtedly incomprehensible to anyone who is not an electronics engineer. These standards are reproduced in the Appendix. They were prepared originally by competent electronics engineers.

Comments: In the ordinary industrial district, standards such as these may be superfluous. With the increase in importance of the field of electronics and the increase in number of laboratories, there may be a wider need for such protection than we now anticipate. The equity of these electromagnetic standards and the problems of measurement and enforcement are subjects on which only electronics experts are qualified to speak.

Radioactive Emissions

The imminence of general use of nuclear reactors as a source of electric power raises the problem of protection from dangerous emissions. These first ordinances using performance standards have not attempted to set up numerical standards for such emissions, although such standards are undoubtedly available. Recognition of the possibility of dangerous radioactive emissions, however, is shown in a few ordinances.

Radioactive materials shall not be emitted to exceed quantities established as safe by the U.S. Bureau of Standards, or as amended from time to time. (Center Line)

The Parsippany-Troy Hills ordinance recognizes "the production of materials by nuclear fission" as a special use requiring a public hearing before a permit can be issued.

Comments: There is probably no immediate need for concern over radioactive emission standards in zoning ordinances. There may be need for concern in the future.

Density and Yard Controls

In Table 7 we have assembled in a much abbreviated form the many controls used to regulate bulk, lot coverage, yards, and density. There are many supplementary provisions affecting these items but little would be gained by trying to list the permissible or required variations.

TABLE 7. DENSITY PROVISIONS

*From center line of street.

**The five bulk zones combine with M1 and M2 zones. M3 has only the one bulk zone.

*** Three inches per foot of distance from front lot line.

Each of the 11 ordinances contains at least one or the forms of density and open-space control.

Perhaps most noteworthy is the fact that controls of this type are being used in industrial districts. In most older ordinances, regulations for industrial districts were confined almost entirely to listing of permitted or prohibited uses. Except where a lot might adjoin a residential district, it was customary to allow construction up to any property line, unlimited height, 100 per cent ground coverage, and to specify no minimum lot area.

Comments: Bulk and density controls such as those shown in Table 7 are not performance standards but are specification standards. Their object, however, is to regulate aspects of industrial development for which we do not now have (and perhaps never will have) suitable objective measurements. These include in particular aesthetics and traffic generation.

Aesthetics. A factory kept to one or two stories and set in a large lot with wide yards is aesthetically pleasing. Several recent court decisions, and in particular, the United States Supreme Court decision in Berman v. Parker, 348 U.S. 26 (1954), show that aesthetics is being recognized as a proper municipal concern. Most industrialists also recognize the importance to themselves of attractive plants, both their own and those of their neighbors.

Traffic Generation. Probably the most disliked effect of industry is the traffic it creates. The only method now known to decrease traffic is to decrease the density of development. If it were possible to set a limit of traffic generation (for example: "no use or density of development that generates in excess of 100 vehicle trips per acre per day will be permitted"), then specification controls such as these would not be needed — at least for the control of traffic. Control of traffic generation by lot area and floor area ratio is far from satisfactory but it can bring a decrease in traffic generation, particularly where a floor area ratio of 0.50 or less is established.

Traffic Noise. Industrial noise limits are applied to the noise from processes and operations of the factory itself. Sometimes these are required only to be kept below the normal street traffic noise, a perfectly logical requirement. If a reduction of density serves to decrease traffic noise, then industrial noise must also be lessened.

More important than traffic noise as the criterion with which to compare industrial noise is the effect of traffic noise itself on neighboring property. Several studies have shown that industrial process noise is a relatively minor offender. All studies have shown traffic noise to be a major offender.

Many of the industrial annoyances for which performance standards are used have the same effects that traffic produces, and for which, when they are caused by traffic, no limits are set. Besides noise, these would include dust and dirt, vibration, carbon monoxide gas, safety, odors, and glare. For this reason, density controls, insofar as they are effective in reducing traffic, may be the most important of all industrial zoning controls.

While it would not be practical to try to describe the density and yard provisions in detail, we can note some of the ranges that are used in the 11 ordinances.

Where minimum lot area has been specified, it various among the different ordinances from 5,000 square feet to 7 acres.

Minimum front yards run from 30 feet to 200 feet. Minimum side yards run from 25 feet to 100 feet.

One ordinance specifies the maximum height of the building to be equal to the street width and this ordinance also calls for a 35-foot front yard. Other maxima run from 25 feet to 75 feet.

In the three ordinances that have specified a maximum lot coverage, one permits a maximum of 30 per cent, another of 35 per cent, and the third of 50 per cent.

Floor area ratios (except for that proposed in the Chicago ordinance) vary from 0.2 up to 2.0.

The Chicago ordinance has three industrial districts and within each industrial district there is assigned one of five different bulk maxima. These vary from 2 times the lot area up to 7.0 times the lot area. This seems to be the weakest part of the entire Chicago proposal.

There should be no fear that reputable industrialists would object to reasonable density standards. Most of the plants constructed recently could easily comply with standards as severe as the most strict of these ordinances. It is probable, however, that some of the more extreme yard provisions would be considered unreasonable.

Use Lists

The goal of performance standards was the complete elimination of all lists of uses. Any use that met the standards for a district was automatically permitted to locate in that district. But there were several questions left unanswered and it was recognized that the goal might never be reached. Several of the ordinances do list uses and the purpose of these lists is analyzed.

In these ordinances there are two quite different methods of applying performance standards. The more common method is to apply the standards to the zoning district regulation: a use to be permitted in a district must meet the standards of the district. In the second method, the performance standards are applied to the description of the uses.

The second method, standards applied to uses, also retains the use lists to a great extent. This is the method used in the Bismarck and Clarkstown ordinances, although there are differences between the two ordinances.

The Bismarck ordinance establishes two manufacturing districts — MA and MB. The major difference between the two districts is that in the MA district the principal uses are "Industrial Group A," while the principal permitted uses in MB districts are "Industrial Group B."

Industries in the two groups correspond generally to the conventional "light" and "heavy" groupings. But in addition they are required to conform to certain performance standards. A brief comparison of the two lists is shown in Table 8.

On objective of performance standards is to permit an industry to locate in any zone if it conforms with the standards set for that zone. The Bismarck ordinance does not provide for Group B uses in a MA district but it does relegate Group A uses to the MB district under the following circumstances.

Industrial Group B ... [shall include] the following uses:

1. Any use listed in Industrial Group A, and involving the use of a punch press over 20 tons rated capacity, a drop hammer, or an automatic screw machine, provided that all other requirements of Industrial Group B uses are complied with.

2. Any use listed under Industrial Group B which cannot comply with the requirements of an Industrial Group A use, provided that all requirements for an Industrial Group B use are complied with.

The Bismarck ordinance was intended as a compromise between true performance standards and the conventional use lists. Insofar as Group B uses cannot be located in the MA district, it fails to meet the objectives of performance standards.

TABLE 8. INDUSTRIAL USES IN BISMARCK ZONING ORDINANCE

Paragraph 4.11 of the Clarkstown ordinance states, "...any non-residential use except those expressly prohibited by this ordinance in Sec. 4.4 may be undertaken and maintained if it conforms to the district Regulations, and the Regulations of this Sec. 4.1, referred to herein as 'Performance Standards,' limiting Dangerous and Objectionable Elements at the point of determination of their existence as provided in this Sec."

The uses prohibited under section 4.4 of the Clarkstown ordinance are the typical list of prohibited uses appearing in earlier ordinances, i.e., asphalt, cement, acid, fertilizer manufacture, lead smelting, slaughterhouses, etc. In other words, the industries generally considered highly objectionable, even though they are able to meet the standards, are still prohibited.

The use of performance standards proposed in the Clarkstown ordinance is somewhat difficult to follow through the text of the ordinance but in brief it is as follows:

All new nonresidential uses must conform to the standards, no matter where they are located.

Certain specific uses must go through performance standards procedure in order to get a building permit or certificate of occupancy. Performance standards procedure requires a hearing before the board of appeals.

Performance standards procedure is required for stated uses in the specific zones as follows:

RO (Residence-Office) district:

"Light" manufacturing

Research, experimental, and testing laboratories

C-2 (Highway Commerce) district: ·

"Light" manufacturing

Dry cleaning, rug cleaning

Laundry plants

Laboratories

M-1 (Light Manufacturing) district:

All manufacturing

Dry cleaning, rug cleaning

Laundry plants

M-2 (General Manufacturing) district:

Same uses as in M-1

Concrete and pavement mixing plants

Junk yards and auto-wrecking yards

Gas-holders, coal yards, and refrigerating plants

Storage and baling of papers within a completely enclosed building

Incineration of waste materials, except garbage, offal, and dead animals

Quarries, stone crushers, screening plants, and storage of quarry screenings.

The building inspector, if he has any doubts, can require any nonresidential use to go through performance standards procedure.

Another ordinance resembles the Clarkstown ordinance in permitting certain uses only after review by a board of appeals.

The Parsippany-Troy Hills Township ordinance contains a list of uses that it terms "special uses ... in which industrial operations are customarily such as to produce traffic congestion, noise, glare, air pollution, water pollution, fire hazards or safety hazards exceeding the standards and limitations established by this Ordinance, ..." The list includes notorious industries such as soap manufacture, acid manufacture, petroleum refining, etc. In general, these would correspond to the prohibited uses in the Clarkstown ordinance.

All certificates of occupancy for industries in Parsippany-Troy Hills must be issued by the board of adjustment after it is satisfied that the industry can and will comply with the standards. For "special uses," however, the board must hold a legal public hearing before issuing its permit.

This provision for public hearing has a two-fold purpose. The first reason for the list is to tackle the problem of psychological effects. If some of these industries, which are so often feared by people, are able to make their operations unobjectionable, then it is better that the public be given a chance to be convinced of this fact. Perhaps, in this manner, the emotional block can be removed.

The second purpose of the public hearing is to eliminate the need for prohibiting any industry by name. Much as we might wish it otherwise, there are still a number of industries that have not found an economical method to clean up their operations. We can be quite certain that such industries will not be willing to face a public hearing or would not survive one if they did.

Most of the ordinances have adhered to the principal of admitting any use in an industrial district if it can meet the standards. The Bismarck and Clarkstown exceptions have been described above. The Anne Arundel County ordinance has a short list that includes the bottling of liquified petroleum gas and the products of nuclear fission, which are permitted only after review by the board of adjustment. The Chicago ordinance contains a list of explosive products that are permitted if licensed by the fire prevention bureau. Penn and Parsippany-Troy Hills townships list no prohibited industrial uses.

The Rye and Southfield Township provisions are for districts that are not strictly industrial. The performance standards in Rye are directed toward laboratories; in Southfield Township the uses are confined to those "charged with the principal function of basic research and technical training" plus accessory dormitory and housing uses.

Off-Street Parking and Loading

Each of the ordinances contains requirements for off-street parking and loading for industrial uses. They are not analyzed here because much more complete analyses of such provisions are available elsewhere.

General Conclusions

There is no reason to believe that the theory behind performance standards for industrial zoning is not still valid. Some major steps have been made toward putting that theory into practice. At the same time, the first handful of ordinances using performance standards exhibit some serious weaknesses.

Probably the most serious weakness is that planners may have ventured into highly technical fields to adopt standards and measurements about which they know very little. This is particularly well illustrated in the standards for noise. For example, one ordinance permits in the industrial district a noise of "85 decibels." This is a rather high level for frequencies under 150 cycles per second but it is probably bearable. However, in the higher ranges, especially above 4,000 cycles, an 85 decibel sound level would be practically insufferable.

Even the typographical errors that go unnoticed and get enacted into law are illustrations of the fact that planners may be getting out of their depth. In the Albuquerque ordinance particulate matter was limited to "0.3 grams per cubic foot" rather than "0.3 grains per cubic foot." A gram is equal to about 15.4 grains. This means that this ordinance would permit the emission of dust in some 15 times as great a quantity as normally is considered acceptable.

We still know very little about how to administer performance standards. However, this is something that we are only going to learn by experience. If some of the schemes that have been proposed thus far are unworkable, as they very well may be, we can't criticize planners too severely. Someone has to take the first steps and it will not be surprising if many of the steps are false.

ENDNOTES

* Dennis O'Harrow, "Performance Standards in Industrial Zoning." Planning 1951 (Chicago: American Society of Planning Officials, 1952) pp. 42–45; Performance Standards in Industrial Zoning, PLANNING ADVISORY SERVICE Information Report No. 32, November 1951 (Chicago: ASPO); Performance Standards in Industrial Zoning (Columbus, Ohio: National Industrial Zoning Committee, 820 Huntington Bank Building).

** For an explanation of the use of the sone as a unit of loudness, see "The Measurement of Industrial Noise," G. L. Bonvallet in American Industrial Hygiene Quarterly, September 1952 (reprinted by National Association of Mutual Casualty Companies, 20 North Wacker Drive, Chicago 6).

APPENDIX

Status of Ordinances Used in This Report

Excerpts from Ordinances for:

Chicago

Clarkstown

Parsippany-Troy Hills Township Southfield Township

Warren Township

CHICAGO

ARTICLE 8, MANUFACTURING DISTRICTS

PERMITTED USES

A. The following uses of land. or buildings are permitted in the districts indicated hereafter. With the exception of:

(1) Uses lawfully established on the effective date of this ordinance, or

(2) Special Uses allowed in accordance with the provisions of Section 8.4,

no building or tract of land shall be devoted to any use other than a use permitted hereafter in the zoning district in which such building or tract of land shall be located. Uses already established on the effective date of this ordinance and rendered non-conforming by the provisions thereof shall be subject to the regulations of Article 5 governing non-conforming uses.

B. No activities involving the storage, utilization, or manufacture of materials or products which decompose by detonation shall be permitted within the City of Chicago, except such as are licensed by the Fire Prevention Bureau. The list of such prohibited materials or products shall include, but shall not be limited to, the following:

1. Acetylides.
2. Azides.
3. Chlorates.
4. Dynamite.
5. Blasting Gelatin.
6. Fulminates.
7. Anhydrous Hydrazine.
8. Ammonium Nitrate.
9. Dinitroresorcinol.
10. Dinitrotoluene.
11. Guanidine Nitrate.
12. Guncotton (Cellulose Nitrate or Pyroxylin).
13. Hexamine.
14. Nitroglycerine.
15. Petn (Pentaerythritoltetranitrate).
16. Picric Acid.
17. Tetryl (Trinitrophenylmethyltramine).
18. Cylonite or Hexogen (Trimethylene Trinitramine).
19. Dinol.
20. Petryl.
21. TNT (Trinitrotoluene).
22. Perchlorates (when mixed with carbonaceous materials).
23. Black Powder.
24. Fireworks.
25. Greek Fire.
26. Permanganates.
27. Peroxides.

8.3-1 Permitted Uses – M1-1, M1-2, M1-3, M1-4, and M1-5

The following uses are permitted in the M1-1to M1-5 districts inclusive, provided that all activities shall take place within enclosed buildings, unless otherwise indicated and except for off-street parking and loading as regulated by Article 10.

1. Any production, processing, cleaning, testing, repair, storage or distribution of materials, goods or products which shall conform with the standards of performance set forth in Section 8.5 to 8.11 inclusive (except such uses as are specifically excluded from the City of Chicago in accordance with the provisions of Section 8.3) and which shall not be injurious or offensive to the occupants of adjacent premises by reason of the emission or creation of noise, vibration, smoke, dust or other particulate matter, toxic and noxious materials, odors, fire or explosive hazards, or glare or heat. Within 300 feet of a Residence District all storage, except of motor vehicles under 1½ ton capacity, shall be in completely enclosed buildings, and storage located elsewhere may be out-of-doors but shall be effectively screened by a solid wall or fence (including solid entrance and exit gates) at least eight feet in height but in no case lower in height than the enclosed storage.
2. Automobile Service Stations – Retail sale of gas and oil for motor vehicles, including minor services commonly incidental thereto, may be conducted outside of a building. Lubrication and washing facilities are permitted if completely enclosed in a building.
3. Banks.
4. Barber Shops, Beauty Parlors, Massage or Similar Personal Service Shops.
5. Building Materials Sales.
6. Contractor Offices and Shops, such as:
   1. Building
   2. Cement
   3. Electrical
   4. Heating, Ventilating, and Air Conditioning
   5. Masonry
   6. Painting
   7. Plumbing
   8. Refrigeration
   9. Roofing
7. Currency Exchanges
8. Drug Stores
9. Fuel and Ice Sales located in completely enclosed buildings.
10. Garages and Parking Lots – for motor vehicles.
11. Greenhouses.
12. Lodges and Labor Organization Headquarters
13. Municipal or Privately-owned Recreation Buildings or Community Centers.
14. Public Utility and Public Service Uses, including:
    10. Electric Sub-stations
    11. Water Pumping Stations
    12. Water Reservoirs
    13. Water Filtration Plants
    14. Fire Stations
    15. Police Stations
    16. Railroad Passenger Stations
    17. Railroad Rights-of-way
    18. Telephone Exchanges
    19. Bus Terminals, Bus turn-arounds
15. Radio and Television Towers.
16. Recreation Centers.
17. Restaurants.
18. Signs, as regulated by Article __.
19. Stadiums, Auditoriums and Arenas with a capacity of 2000 seats or less.
20. Taverns.
21. Trade Schools.
22. Dwelling Units for watchmen and their families located on the premises where they are employed in such capacity.
23. Accessory Uses.

8.3-2 Permitted Uses - M2-1, M2-2, M2-3, M2-4, and M2-5

The following uses are permitted in the M2-1 to M2-5 Districts inclusive provided that within 300 feet of a Residence District all activities, including storage, shall take place within enclosed buildings, unless otherwise indicated and except for off-street parking and loading as regulated by Article 10.

1. Any production, processing, cleaning, testing, repair, or storage of materials, goods or products which shall con­ form with the standards of performance set forth in Sections 8.5 to 8.11 inclusive, (except such uses as are specifically excluded from the City of Chicago in accordance with the provisions of Article 8.3) and which shall not be injurious or offensive to the occupants of adjacent premises by reason of the emission or creation of noise, vibration, smoke, dust or other particulate matter, toxic and noxious materials, odors, fire or explosive hazards, or glare or heat.

2. Any other use permitted in the M1-1 to M1-5 Districts inclusive and subject to the same restrictions attaching thereto within 300 feet of a Residence District.

8.3-3 Permitted Uses – M3

The following uses are permitted in the M3 District provided that all activities shall take place within enclosed buildings, unless otherwise indicated and except for off street parking and loading as regulated by Section 10.

1. Any production, processing, cleaning, te1ting, repair or storage of goods or products which shall conform with the standards of performance set forth in Sections 8.5 to 8.11 (except such uses as are specifically excluded from the City of Chicago in accordance with the provisions of Section 8.3.)

2. Any other use permitted in the M1-1 to M1-5 Districts inclusive and subject to the same restrictions attaching thereto within 300 feet of a Residence District.

8.4 SPECIAL USES

The following uses may be allowed as Special Uses in the Districts indicated hereafter by the Zoning Administrator in accordance with the provisions of Section __.

8.4-1 Special Uses – M1-1, M1-2, M1-3, M1-4, and M1-5

1. Airports or Aircraft Landing Fields, Heliports.
2. House Trailer Camps.
3. Parks and Playgrounds.
4. Penal and Correctional Institutions.
5. Planned Large-scale Industrial Developments.
6. Stadiums, Auditoriums, and Arenas with a capacity of over 2000 seats.
7. Theaters, drive-in.

8.4-2 Special Uses – M2-1, M2-2, M2-3, M2-4, and M2-5

1. Any use allowed as a Special Use in the M1-1 to M1-5 Districts inclusive except House Trailer Camps.
2. Junk Yards.

8.4-3 Special Uses – M3

1. Any use allowed as a Special Use in the M2-1 to M2-5 Districts inclusive.
2. Extraction of Gravel, Sand or Other Raw Materials.
3. Incinerators – municipal.
4. Area for Dumping or Disposal of Garbage, Refuse or Trash.

8.5 PERFORMANCE STANDARDS – NOISE

Any use established in a Manufacturing District after the effective date of this ordinance shall be so operated as to comply with the maximum performance standards governing noise set forth hereinafter for the district in which such use shall be located. No use already established on the effective date or this ordinance shall be so altered or modified as to exceed, or if already exceeding so as to further exceed, the maximum performance standards governing noise established hereinafter for the district in which such use is located. Objectionable sounds of an intermittent nature shall be controlled so as not to become a nuisance to adjacent uses.

Sound levels shall be measured with a sound level meter and associated octave band filter manufactured according to standards prescribed by the American Standards Association.

8.5-1 Performance Standards – Noise – M1-1, M1-2, M1-3, M1-4, and M1-5

1. At no point on the boundary of a Residence or Business District shall the sound pressure level of any operation conducted in the M1-1 to M1-5 Districts (other than the operation of motor vehicles or other transportation facilities) exceed the decibel levels in the designated octave bands shown below for the districts indicated.

8.5-2 Performance Standards – Noise – M2-1, M2-2, M2-3, M2-4, and M2-5

The performance standards governing noise in the M1-1 to M1-5 Districts inclusive shall apply to all uses in the M2-1 to M2-5 Districts inclusive.

8.5-3 Performance Standards – Noise – M3

The performance standards governing noise in the M1-1 to M1-5 Districts inclusive shall apply to all uses in the M3 District.

PERFORMANCE STANDARDS – VIBRATIONS

Any use established in a Manufacturing District after the effective date of this ordinance shall be so operated as to conform with the performance standards governing vibration set forth hereinafter for the district in which such use shall be located. No use already established on the effective date of this ordinance shall be so altered or modified as to conflict with, or if already in conflict with, so as to further conflict with, the performance standards governing vibration established hereinafter far the district in which such use is located.

8.6-1 Performance Standards – Vibration – M1-1, M1-2, M1-3, M1-4, and M1-5

In the M1-1 to M1-5 Districts inclusive any use creating intense earth-shaking vibration shall be set back at least five hundred feet from the lot lines on all sides, except for lot lines adjoining an M3 District where such setback shall not be required, but in no case shall any such vibration be perceptible along the boundary line of any other zoning district except M3.

8.6-2 Performance Standards – Vibration – M2-1, M2-2, M2-3, M2-4, and M2-5

The performance standards governing vibration in the M1-1 to M1-5 Districts inclusive shall apply to all uses located in the M2-1 to M2-5 Districts inclusive.

8.6-3 Performance Standards – Vibrations – M3

Any use creating intense earth-shaking vibrations shall be set back at least five hundred feet from the boundary of a Residence, Business, Commercial, M1 or M2 District, but in no case shall any such vibration be perceptible along the boundary of any other zoning district.

8.7 PERFORMANCE STANDARDS – SMOKE AND PARTICULATE MATTER

1. Any use established in a Manufacturing District after the effective date of this ordinance shall be so operated as to conform with the performance standards governing smoke and particulate matter set forth hereinafter for the district in which such use shall be located. No use already established on the effective date of this ordinance shall be so altered or modified as to conflict with, or if already in conflict with, so as to further conflict with, the performance standards governing smoke and particulate matter established hereinafter for the district in which such use is located.
2. In addition to the performance standards specified hereinafter, the emission of smoke or particulate matter in such manner or quantity as to be detrimental to or endanger the public health, safety, comfort, or welfare is hereby declared to be a public nuisance and shall henceforth be unlawful.
3. For the purpose of grading the density of smoke, the Ringelmann Chart currently published and used by the United States Bureau of Mines shall be employed. The emission of smoke or particulate matter of a density equal to or greater than No. 3 on the Ringelmann Chart is prohibited at all times, except as otherwise provided hereinafter.
4. The emission from all sources within any lot area during any one hour of particulate matter containing more than 10% by weight of particles having a particle density larger than 44 microns is prohibited.
5. Dust and other types of air pollution borne by the wind from such sources as storage areas, yards, roads and so forth within lot boundaries shall be kept to a minimum by appropriate landscaping, paving, oiling, or other acceptable means. Emission of particulate matter from such sources in excess of the weight limitations specified hereinafter is prohibited.

8.7-1 Performance Standards – Smoke and Particulate Matter – M1-1, M1-2, M1-3, M1-4, and M1-5

1. The emission of more than 15 smoke units per hour per stack is prohibited. However, during one l hour period in each 24 hour day, each stack may emit up to 30 smoke units when blowing soot or cleaning fires. Only during fire cleaning periods, however, shall smoke of a density up to Ringelmann No. 3 be permitted and then for not more than 4 minutes.
2. The rate of emission of particulate matter from all sources within the boundaries of any lot shall not exceed a figure of l pound per acre of lot area during any one hour, after deducting from the gross hourly emission per acre the correction factors set forth in Tables 1, 2, and 3 below for height, velocity, and temperature of emission respectively. Determination of the total rate of emission of particulate matter within the boundaries of any lot shall be made as follows:
   1. Determine the maximum emission in pounds per hour from each source of air pollution and divide this figure by the number of acres of lot area – thereby obtaining the gross hourly rate of emission in pounds per acre.
   2. From each gross hourly rate of emission derived in a. above, deduct the appropriate correction factor (interpolating as required) for height, velocity and temperature of emission set forth in Tables l, 2 and 3 which follow – thereby obtaining the net rate of emission in pounds per acre per hour from each source of air pollution.
   3. Add together the individual net rates of emission derived in b. above to obtain the total net rate of emission from all sources of air pollution within the boundaries of the lot. Such total shall not in the M1-1 to M1-5 Districts exceed l pound per acre of lot area during any one hour.

Table 1 Allowance for Height of Emission*

*Interpolate for intermediate values not shown on table.

Table 2 Allowance for Velocity of Emission*

*Interpolate for intermediate values not shown on table.

Table 3 Allowance for Temperature of Emission*

*Interpolate for intermediate values not shown on table.

8.7-2 Performance Standards – Smoke and Particulate Matter – M2-1, M2-2, M2-3, M2-4, and M2-5

1. The emission of more than 30 smoke units per hour per stack is prohibited; including smoke of a density in excess of Ringelmann No. 2. However, during 4 one hour periods in each 24 hour day, each stack my emit up to 45 smoke units, twice for blowing of soot, and twice for cleaning fires. Only during fire cleaning periods smoke of a density up to Ringelmann No. 3 shall be permitted and then for not more than 4 minutes per period.
2. The rate of emission of particulate matter from all sources within the boundaries of any lot shall not exceed a net figure of 3 pounds per acre of lot area during any one hour, after deducting from the gross hourly emission per acre the correction factors set forth in Tables 1, 2 and 3 below for height, velocity, and temperature of emission respectively. Determination of the total net rate of emission of particulate matter within the boundaries of any lot shall be made as follows:
   1. Determine the maximum emission in pounds per hour from each source of air pollution and divide this figure by the number of acres of lot area – thereby obtaining the gross hourly rate of emission in pounds per acre.
   2. From each gross hourly rate of emission derived in a. above, deduct the appropriate correction factor (interpolating when necessary) for height, velocity, and temperature of emission set forth in Tables 1, 2, and 3 which follow – thereby obtaining the net rate of emission in pounds per a ere per hour from each source of emission.
   3. Add together the individual net rates of emission derived in b. above to obtain the total net rate of emission from all sources of air pollution within the boundaries of the lot. Such total shall not in the M2-1 to M2-5 Districts inclusive exceed three pounds per acre of lot area during any one hour.

Table 1 Allowance for Height of Emission*