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Air Pollution 12-67

Particulate Dispersion

The double normal Gaussian model just discussed is valid for gases and suspended particulate matter.

In addition, the model can be modiﬁed to handle settleable particulate matter. This is usually deﬁned as

those particles greater than 40 microns in diameter. (A typeset period on this page is about 1000 microns

in diameter.) We are interested in having a model consider particulate settling because in some instances

surface deposition of a toxic particle from an elevated plume is very important to know. Instead of the

model calculating pollutant concentration, we may be more interested in mass of deposition per unit

area per unit time.

Examining the dynamics of particles settling out of an elevated plume, we can differentiate the

centerline of the gaseous portion of the plume from the centerline of the settleable particulate portion

of the plume. Considering only the settleable particulate plume centerline, we note that for each size

class of particle there is a distance downwind beyond which no more particles of that size will be found

because they have all settled to the ground. In other words, the plume centerline for that particle size

has disappeared. We can represent the disappearance of that particle size class with a plume centerline

that tilts downward from near the top of the stack and eventually disappears downwind into the surface.

This type Gaussian model is referred to as a tilted plume model.

The amount of plume tilt is determine from the terminal settling velocities of the various sizes of

particles in the plume, the distance downwind where they have settled out, and the mean wind speed.

If the terminal settling velocity of the particle is deﬁned as V

, the downwind distance as x, and the wind

speed as u, the ratio V

x/u can be used to shift the plume centerline downward. Equation (12.53) is the

familiar Gaussian model with the plume-shift term incorporated.

(12.53)

Additionally, the mass deposition rate of particulate in a given area can be determined by multiplying

the concentration deposited by the terminal settling velocity. This is given by the following equation.

(12.54)

Regulatory Air Models

From the ﬁrst basic Gaussian air models, an entire library of models has developed with each new model

being employed for new uses or being a reﬁnement of an existing model. As a result of continuous

updating and advancement of air models, the use of speciﬁc models in regulatory applications changes

as new models become available.

In regulatory efforts the use of a speciﬁc model is based on the desired result of the modeling. For

example, the use of a simple Gaussian model to describe the impact of a major source in complex terrain

is beyond the capabilities of the model and is therefore not recommended. However, if only rough

estimates are required for a single source on open terrain, the simple Gaussian model would probably

sufﬁce. Because of the existence of these types of situations, individual models are recommended for

speciﬁc applications. Tables 12.18 and 12.19 are a listing of the regulatory air models and their applications

currently preferred or recommended as alternatives by the U.S. EPA.

Cx yz

zHVxu

syz y

,, exp

()

[]

pss s s

xyz

zHVxu

syz y

,, exp

()

[]

12-68 The Civil Engineering Handbook, Second Edition

TA BLE 12.18 Preferred Air Quality Models

Preferred Models

Buoyant line and point source dispersion model

(BLP)

BLP is a Gaussian plume dispersion model for plume rise and

downwash effects from stationary line sources.

CALINE3 CALINE3 is used to estimate the concentrations of nonreactive

pollutants emanating from highway trafﬁc.

Climatological dispersion model (CDM 2.0) CDM is a climatological steady-state Gaussian plume model for

seasonal or annual arithmetic average pollutant concentrations in an

urban area.

Gaussian-plume multiple source air quality

algorithm (RAM)

RAM is a Gaussian plume model for estimating relatively stable

pollutants from point and area sources in level terrain.

Industrial source complex model (ISC3) ISC3 is a Gaussian plume model to describe an industrial source

complex in either short- or long-term models with limited terrain

adjustment.

Urban airshed model (UAM) UAM is a three-dimensional urban simulation model for estimating

ozone concentrations from short-term conditions.

Offshore and coastal dispersion model (OCD) OCD is a Gaussian model developed to estimate the effect of offshore

sources on coastal regions.

Emissions and dispersion modeling system

(EDMS)

EDMS is a combined emissions/dispersion model for assessing

pollution at civilian airports and military air bases.

Complex terrain dispersion model plus algorithms

for unstable conditions (CTDMPLUS)

CTDMPLUS is a reﬁned point source Gaussian air quality model for

use in all stability conditions for complex terrain situations.

Source: 40 CFR 51 Appendix A to Appendix W.

TA BLE 12.19 Alternative Air Quality Models

Alternative Models

AVACTA II Model AVACTA II is a Gaussian model that describes atmospheric dispersion in

terms of segment or puff elements. It is particularly suited to simulations

of sulfur species but can simulate virtually any pair of primary-secondary

pollutants.

Dense Gas Dispersion Model DEGADIS DEGADIS is used to model the transport of toxic chemical releases in to

the atmosphere.

ERT Visibility Model The ERT visibility model is designed to address visibility impairment for

arbitrary lines of sight.

HGSYSTEM HGSYSTEM is a system of linked models that estimate near and fair-ﬁeld

dispersion from spills of either two-phase, nonreactive multi-compound

mixtures or hydrogen ﬂuoride with reactions.

Higher Order Turbulence Model for

Atmospheric Circulation/Random Puff

Tr ansport and Diffusion HOTMAC/

RAPTAD

HOTMAC/RAPTAD combines an Eulerian mesoscale weather prediction

model with a Lagrangian random puff model to forecast transport and

diffusion over complex terrain. It is signiﬁcantly different in its physics

and modeling system than most regulatory models presented here.

LONGZ LONGZ is a steady-state Gaussian plume model for urban and rural areas

that estimates annual average concentrations of pollutants from up to

14,000 sources.

Maryland Power Plant Siting Program

(PPSP) Model

PPSP is a Gaussian plume model applicable to tall stacks in either rural or

urban areas with simple terrain.

Mesoscale Puff Model (MESOPUFF II) MESOPUFF II is a short-term, regional scale puff model used to estimate

concentrations of up to ﬁve pollutant species.

Mesoscale Transport Diffusion and

Deposition Model for Industrial Sources

(MTDDIS)

MTDDIS is a variable trajectory Gaussian puff model for long-range

transport of point source emissions over level or rolling terrain.

Multi-Source (SCSTER) Model SCSTER is a steady state, Gaussian dispersion model for multiple sources

in urban or rural terrain. SCSTER is a modiﬁed version of the EPA

CRSTER model.

Air Pollution 12-69

References

Calvert, S., Goldschmid, J., Leith, D., and Mehta, D. 1972. Wet scrubber system study. Scrubber Handbook,

Vo lume I. U.S. Department of Commerce, NTIS. PB-213016.

Cooper, C. D. and Alley, F. C. 1990. Air Pollution Control: A Design Approach. Waveland Press, Prospect

Heights, IL.

Environmental Resources Management. 1992. Clean Air Act Primer.

Frizzola, J. A., et al. 1979. Calculation of effective stick height. In Recommended Guide for the Prediction

of the Dispersion of Airborne Efﬂuents, ed. J. R. Martin, pp. 38–44. The American Society of

Mechanical Engineers, New York.

Hansen, L. D. 1994. A critical evaluation of the Nextel advantage. Class Report, C.E. 457, Purdue

University.

Leonard, R. L. 1977. Air Quality Permitting. Lewis Publishers, Boca Raton, FL.

Lodge, J. R. Jr., ed. 1989. Methods of Air Sampling and Analysis. Lewis Publishers, Chelsea, MI.

Makansi, J. 1988. Reducing NO

emissions: A special report. Power. September.

Nagy, G. Z. 1991. The odor impact model. J. Air Waste Manage. Assoc. 41 (10):1360–1362.

Pack, D. H. and Halitsky, J. 1979. Behaviour of airborne efﬂuents. In Recommended Guide for the Prediction

of the Dispersion of Airborne Efﬂuents, ed. J. R. Martin, pp. 16–37. The American Society of

Mechanical Engineers, New York.

Pedersen, E. 1993. An analysis of sintamatic baghouse ﬁlter media. Class Report, C.E. 457, Purdue

University.

Prokop, W. H. 1992. Air Pollution Engineering Manual — Odors. Air and Waste Management Association.

Van Nostrand Reinhold, New York.

Smith, D. J. 1993. Low-NO

burners lead technologies to meet CAA’s Title IV. Power Engineering. June.

Smith, M. E., et al. 1979. Calculations of dispersion and deposition. In Recommended Guide for the

Prediction of the Dispersion of Airborne Efﬂuents, ed. J. R. Martin, pp. 43–55. The American Society

of Mechanical Engineers, New York.

PANACHE PANACHE simulates continuous or short term pollution dispersion via

Eulerian or Lagrangian ﬁnite volume ﬂuid mechanics code. Complex

terrain and source, receptor relationships can be modeled.

Plume Visibility Model (PLUVUE II) PLUVUE II is used for estimating visual range reduction and atmospheric

discoloration from a single emission source.

Point, Area, Line-Source Algorithm

(PAL-DS)

PAL-DS is an algorithm for estimating short-term dispersion from line,

point, or area sources based on steady state Gaussian plume assumptions.

Reactive Plume Model (RPM-IV) RPM-IV is used for estimating short-term concentrations of primary and

secondary reactive pollutants from point or area sources.

Shoreline Dispersion Model (SDM) SDM is a multipoint Gaussian model that calculates source impacts from

fumigation events.

SHORTZ SHORTZ uses the steady-state bivariate Gaussian plume model to estimate

ground-level concentrations in urban and rural terrain for both simple

and complex terrain.

Simple Line-Source Model The Simple Line-Source Model is used to determine exhaust concentrations

within 100 meters of a roadway in relatively ﬂat terrain.

SLAB SLAB estimates spatial and temporal distributions of short-term ambient

concentrations resulting from the release of denser than air gases.

WYNDValley Model WYNDValley is a multilayer Eularian grid dispersion model that permits

ﬂexibility in modeling.

Source: 40 CFR 51 Appendix A to Appendix W

TA BLE 12.19 (continued) Alternative Air Quality Models

Alternative Models

12-70 The Civil Engineering Handbook, Second Edition

Tchobanoglous, G. 1979. Wastewater Engineering: Treatment, Disposal, and Reuse. Metcalf and Eddy, Inc.,

McGraw-Hill, New York.

Turner, D. B. 1969. Workbook Atmospheric Dispersion Estimates. U.S. Public Health Service, Cincinnati,

OH.

Turner, D. B. 1979. Meteorological fundamentals. In Recommended Guide for the Prediction of the Dis-

persion of Airborne Efﬂuents, ed. J. R. Martin, pp. 1–15. The American Society of Mechanical

Engineers, New York.

U.S. EPA. 1993. Guidelines on Air Quality Models. Research Triangle Park.

U.S. EPA. 1993. Compilation of Air Pollutant Emission Factors. Research Triangle Park.

Wark, K. and Warner, C. F. 1981. Air Pollution, Its Origin and Control. Harper & Row, New York.

Weber, J. 1972. Adsorption. In Physicochemical Processes for Water Quality Control, pp. 199–259. John

Wiley & Sons, New York.

Incinerators

13.1 Regulations and Regulatory Background

Incineration and Clean Air Laws • Incinerator Regulation

Under the Toxic Substances Control Act • Incinerator

Regulation Under the Resource Conservation and Recovery

Act • Deﬁnition of Solid, Hazardous, and Medical Waste •

Regulation of Incinerators • Oxygen Correction Factors •

Regulatory Requirements for Risk Assessments

13.2 Principles of Combustion and Incineration

Thermodynamics

13.3 Combustion Chemistry

Particulate and Metal Fume Formation • Material and Energy

Balances

13.4 Incineration and Combustion Systems

Nonhazardous Waste Incinerators • Hazardous Waste

Incinerators • Boilers and Industrial Furnaces

13.5 Air Pollution Control and Gas Conditioning Equipment for

Incinerators.

Quench • Heat Recovery Systems • Electrostatic Precipitators •

Fabric Filters • High-Efﬁciency Particulate Absolute Filters •

Gas Atomized (Venturi) Scrubbers • Hydrosonics™ Scrubber •

Ionizing Wet Scrubbers • Packed Bed and Tray Tower Scrubbers •

Dry Scrubbing Systems • Compliance Test for Hazardous Waste

Incinerators • POHC Selection — Incinerability Ranking

Many types of devices are used for incineration. The most obvious are incinerators, which are furnaces

especially designed and built to burn wastes. However, wastes, especially hazardous wastes, are also burned

in boilers and industrial furnaces, mainly cement and aggregate kilns. Approximately 50% of the incin-

erable hazardous wastes produced in the United States in 1993 were burnt in cement kilns. Irrespective

of the type of furnace used, as soon as it burns wastes, it becomes subject to all appropriate laws and

regulations that govern the handling, storage, and combustion of wastes.

When properly performed, incineration is highly efﬁcient, destroying virtually all organic contami-

nants, reducing the volume of material to be landﬁlled, and producing extremely low levels of air

emissions. Incineration facilities frequently encounter opposition from neighbors and from political

groups, and it can be argued that such opposition represents the greatest barrier to its widespread use.

Incineration is also heavily regulated by federal, state, and local statutes and regulations. The regulations

govern every facet of the design, construction, testing, and operation of all waste combustion facilities,

and a thorough understanding of the legal aspects is essential to successful operation of an incineration

facility. The regulatory requirements are brieﬂy discussed below, but because of their complexity and the

fact that they are subject to frequent changes, the reader is strongly urged to contact all appropriate

regulatory agencies to obtain the latest regulatory standards and requirements before proceeding with

any facet of waste management. A convenient development of the last 10 years is the posting of regulations,

Leo Weitzman

LVW Associates, Inc.

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The Civil Engineering Handbook, Second Edition

guidance documents, test methods, and other information on the World Wide Web. The text includes

references to websites containing detailed information. The websites are operated by the various govern-

ment agencies and are generally kept up-to-date; however, with time, addresses may change.

The following discussion restricts itself to the law currently in the U.S. Virtually every environmental

law in effect can apply to

an incineration facility. Many facilities are subject to state and local statutes

that, in the U.S., are usually similar, and often identical, to the federal laws. Throughout the world,

environmental requirements for incinerators set different limits on allowable releases, but the types of

contaminants that are regulated are generally similar. As a result, all environmental laws have an inherent

similarity that makes an understanding of one set of comprehensive laws applicable to an understanding

of any other set. The discussion is to be considered descriptive of the general concepts of the laws.

13.1 Regulations and Regulatory Background

The following four laws in the U.S. are the most important to waste combustion:

1. The Clean Air Act of 1972 and its subsequent amendments and reauthorizations (most recent being

1990) specify ambient concentrations of a variety of air pollutants and limit the emissions of

hazardous or toxic air pollutants from all sources, including some nonhazardous waste incinerators.

2. The Toxic Substances Control Act (TSCA) bans the use of polychlorinated biphenyls (PCB) and

sets strict regulations for their incineration and disposal by other means. This law only impacts

incinerators burning polychlorinated biphenyls, PCBs.

3. The Resource Conservation and Recovery Act (RCRA) of 1976 and its successors, the Hazardous

and Solid Waste Amendments (HSWA), are the basis for regulation of all wastes, and speciﬁcally,

of incineration.

4. The Clean Water Act applies to all efﬂuents to any waterway or wastewater treatment plant.

An incineration facility includes units for receiving, storing, pretreating (if necessary), transferring,

and burning of the wastes. It usually also includes laboratory facilities for testing wastes received and

samples of discharge streams, and other facilities related to recordkeeping. The laws require that extensive

and detailed records be kept. Most of these activities, including incineration of hazardous and medical

wastes, are regulated under solid waste (in the U.S. RCRA) laws. The incineration of nonhazardous waste

is regulated under the clean air laws as well as under RCRA and, in the U.S., the incineration of PCB

wastes is regulated under TSCA. The application of the clean water legislation to incinerators is equivalent

to that for any wastewater discharge and is not covered further herein.

Incineration and Clean Air Laws

The ﬁrst signiﬁcant environmental regulations for incinerators in the United States were promulgated

under the Clean Air Act (CAA) of 1972. The CAA required that states set up regulatory programs to

reduce the ambient concentrations of the following ﬁve general categories of air pollution, called criteria

pollutants:

•Particulate

•Sulfur oxides (SO

and SO

)

•Nonmethane hydrocarbons (HC)

•Nitrogen oxides (NO

)

•Carbon monoxide (CO)

All sources of air pollution, including incinerators, are required to meet emission standards for

particulate. While in theory all sources were also required to meet hydrocarbon and CO standards, the

CO limits in many cases were set at levels greater than typically found in most incinerators. Note that

more recently, waste combustion laws have set more stringent limits on CO emissions.

Incinerators

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The limits on SO

and NO

and total hydrocarbons are generally imposed only when the facility is in

an area that does not meet the ambient air quality standards speciﬁed by the CAA — termed a “nonat-

tainment” area — and when the potential emissions of these contaminants exceeds a speciﬁed value.

Many large incinerators, boilers, cement kilns, and other industrial furnaces used for hazardous waste

destruction can be major sources of contaminants; hence, CAA regulations inﬂuence their normal

operation. Some of the regulatory restrictions under the CAA and subsequent amendments established

that may impact incinerators and BIFs include:

•The Prevention of Signiﬁcant Deterioration (PSD) requires that any major emission source in an

area where the ambient air quality is currently being met must have sufﬁciently low emissions so

that it will not signiﬁcantly worsen it. The intent was to assure that the facility not degrade the

air quality in areas that had better than the minimum speciﬁed by the CAA up to the maximum.

All new major sources built in nonattainment areas are subject to New Source Reviews (NSR) to

assure that they will not contribute to a signiﬁcant further decrease in ambient air quality.

•National emission standard hazardous air pollutant (NESHAP) regulations regulate the emissions

of speciﬁc, toxic pollutants.

• State and local governments place restrictions on the emission of speciﬁc compounds and sub-

stances classiﬁed as toxic.

•Restrictions on the emissions of metals, HC1, and toxic organics are made based on risk to health

and the environment (as determined by a risk assessment) in addition to the limits speciﬁed in

regulations.

The Clean Air Act was extensively amended and expanded in its 1990 reauthorization (PL0101–549,

101

Congress, Nov. 15, 1990). These amendments resulted in major changes to the types of contaminants

regulated and to the procedures to be followed for their regulation.

Emission standards for municipal waste combustors under the Clean Air Act are published in 40 CFR

§60, subpart Ca, 40 CFR §60.30a through §60.39a. These standards place limits on the emissions of

particulate and the other criteria pollutants, acid gas (especially hydrogen chloride), chlorodibenzodioxins

(CDDs), and chlorodibenzofurans (CDFs). They also specify the procedures for compliance testing,

operator training, and reporting and recordkeeping.

Virtually all boilers and industrial furnaces, whether they burn hazardous waste or not, are subject to

signiﬁcant regulation under the Clean Air Act. These regulations still apply even when the units burn

wastes or engage in other activities that are subject to RCRA standards. When more than one law applies,

the more stringent of the applicable regulations must be obeyed.

Incinerator Regulation Under the Toxic Substances Control Act

The Toxic Substances Control Act (TSCA) governs the incineration of polychlorinated biphenyls (PCBs).

PCBs are a class of compounds that was used extensively for many industrial applications, especially as

dielectric ﬂuids, and which were banned under TSCA. Such separation of PCB handling from the handling

of other wastes is unique to the U.S. The PCB incinerator regulations are codiﬁed in 40 CFR §761.70,

Annex I, which requires the following:

•For a solids incinerator, PCB emissions are not to exceed 1 mg per kg of PCB fed to the incinerator —

this corresponds to a destruction and removal efﬁciency (DRE) of 99.9999%.

•Particulate emissions must be controlled to a level speciﬁed by the EPA Regional Administrator

or, for systems to be operated in more than one region, the Director, Exposure Evaluation Division

of Ofﬁce of Pesticides and Toxic Substances (OPTS) of the EPA.

•The HCl must be controlled, and the level of control for each facility must be speciﬁed by the

EPA Regional Administrator or, for systems to be operated in more than one region, the Director,

Exposure Evaluation Division of OPTS.

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The Civil Engineering Handbook, Second Edition

•The incinerator must satisfy the following combustion conditions 40 CFR §761.70:

• 1200°C (±100°C) with 3% oxygen and a 2-sec gas residence time in the combustion chamber

• 1600°C (±100°C) with 2% oxygen and a 1-sec gas residence time in the combustion chamber.

•A combustion efﬁciency, CE, greater than 99% as calculated by the following equation:

(13.1)

•where CO

is the molar or volume fraction of carbon dioxide in the exit gas from the com-

bustion chamber, and CO is the molar or volume fraction of carbon monoxide in the exit gas

from the combustion chamber.

•The incinerator must be tested (trial burn) prior to use, and it must contain sufﬁcient monitors

and safety interlocks to automatically shut off the PCB feed if minimum operating conditions are

not met.

Incineration is regulated under TSCA for wastes containing more than 500 ppm PCB. Wastes con-

taining more than 500 ppm PCB may only be destroyed in an approved incinerator or equivalent pursuant

to 40 CFR §761.60(e). The TSCA Regulations for PCB waste allow the disposal of “mineral oil dielectric

ﬂuid” and other liquids contaminated with less than 500 ppm PCB in a “high efﬁciency boiler” deﬁned

as one meeting the following requirements 40 CFR §761.60:

1. The boiler is rated at a minimum of 50 MMBtu/hr (Million Btu/hr).

2. For natural gas and oil-ﬁred boilers, the concentration of CO

50 ppm and O

≥

3%.

3. For coal-ﬁred boilers, the concentration of CO

100 ppm and O

≥

3%.

4. The PCB-contaminated ﬂuid does not comprise more than 10% on a volume basis of the fuel

feed rate.

5. The boiler must be at operating temperature when the PCB-contaminated material is fed. No

waste feed is permitted during startup or shutdown.

6. The owner and operator must comply with monitoring and recordkeeping requirements described

in 40 CFR § 760.60(6).

Since, approximately, 1999, the regulation of PCB incinerators has been consolidated under the RCRA

hazardous waste combustion program that is discussed in the following section.

Incinerator Regulation Under the Resource Conservation and Recovery Act

The “Resource Conservation and Recovery Act” of 1976 (RCRA) as amended in 1986 under the name

“Hazardous and Solid Waste Amendments” (HSWA) requires that the EPA promulgate regulations

governing the handling of all wastes. The term RCRA is commonly used to refer to RCRA, HSWA, and

subsequent amendments, and it will be similarly used herein.

In the U.S., the RCRA regulations are given in the Code of Federal Regulations, 40 CFR §260 through

§280, which set design and performance standards for waste generation, storage, transport, disposal, and

treatment. The RCRA regulations set standards for all aspects of waste management, including standards

for the following:

•Generators and transporters of hazardous wastes

•Owners and operators of treatment, storage, and disposal facilities

•Waste combustion devices also fall under this heading.

The general requirements for all treatment, storage, and disposal (TSD or TSDF) facilities are described

in “Standards for Owners of Hazardous Waste Treatment, Storage, and Disposal Facilities,” 40CFR §264,

which specify that an owner or operator satisfy requirements such as the following:

%CE CO CO CO

()

[]

100

Incinerators

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•Construct all facilities such as storage tank farms, drum storage areas, waste receiving areas, and

landﬁlls in a manner that minimizes the environmental impact of routine operations and upset

conditions.

•Develop a contingency plan and emergency procedures to cope with spills, ﬁres, and other accidents.

•Maintain records of waste produced, treated, and disposed, and identify their fate or disposition.

•Develop a closure and postclosure plan, which includes costs, and show that money will be available

to implement the plan.

•Meet ﬁnancial requirements that verify that he has the ability to clean up in case of an accident

or close his facility after its useful life is over.

•Manage containers, tanks, surface impoundments, waste piles, and landﬁlls properly.

The general requirements for all treatment, storage, and disposal (TSD or TSDF) facilities are described

in “Standards for Owners of Hazardous Waste Treatment, Storage, and Disposal Facilities,” 40 CFR §264,

which specify that such facilities meet minimum facility-wide standards. All hazardous waste incinerators

are subject to the general standards for storage and disposal as well as the speciﬁc standards dealing with

the incineration process. For more detailed guidance, consult “Permit Applicants’ Guidance Manual for

the General Facility Standards of 40 CFR §264” SW-968, (EPA, 1983) and “Risk Burn Guidance for

Hazardous Waste Combustion Facilities” (EPA, 2001).

The RCRA regulations require owners and operators of all TSD facilities to obtain an operating permit

from the appropriate regulatory agency, the EPA Regional Ofﬁce, or if authority has been so transferred,

a state agency. To obtain a permit, the applicant submits the following general information as well as

process (e.g., container storage, tank treatment, land disposal, incineration, etc.) information:

•Description of the facility

•Description of the waste

•Security procedures and inspection schedule

•Contingency plan

•Description of preventive maintenance procedures

•Personnel training program

•A closure plan including cost estimates

•Assurance that the operator of the facility is ﬁnancially able to assume this responsibility

Deﬁnition of Solid, Hazardous, and Medical Waste

RCRA classiﬁes a waste as any material that has no value and that is commonly disposed. It further

speciﬁcally excludes from this deﬁnition, any waste material discharged to the air (and regulated under

the Clean Air Act) or to a wastewater treatment plant or waterway (and regulated under the Clean Water

Act). This is a simplistic deﬁnition, but it is reasonably adequate in most circumstances. See 40 CFR

§260.10 for the legal deﬁnitions of the terms related to waste.

A solid waste can be further classiﬁed as a nonhazardous waste, a medical waste, or a hazardous waste.

The classiﬁcation governs the regulations for the waste’s incineration and, hence, deﬁnes the types and

operating conditions for the combustors that may be used. A nonhazardous waste is any solid waste that

does not meet the requirements for a medical waste or a hazardous waste. Certain wastes, such as

household and commercial refuse, are classiﬁed to be nonhazardous by law. Similarly, certain high volume

industrial wastes, such as mine tailings and ash from combustion of coal, are classiﬁed by law as

nonhazardous. Medical wastes are characterized by their potential to contain some form of pathogen.

Wastes from a hospital are an example. As can be seen, the classiﬁcations are generally made on the basis

of exclusions, that is, (1) a waste material is a solid waste if it is not an air pollutant or a wastewater, and

(2) a solid waste is a nonhazardous waste if it does not meet the deﬁnition of a hazardous or medical

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The Civil Engineering Handbook, Second Edition

waste. The deﬁnition of a hazardous waste thus becomes critical to that of the other types of wastes. A

waste is classiﬁed as hazardous under RCRA if:

1. It exhibits any of the following characteristics:

(a)

Ignitability:

It is ignitable, detonates readily, or it is an oxidizing agent, which causes other

materials to ignite or burn as deﬁned in 40 CFR §261.21 (Waste Category D001).

(b)

Corrosivity:

It has a pH of less than 2 or more than 12.5 or is corrosive to steel as deﬁned in

40 CFR §261,22 (Waste Category D002).

(c)

Reactivity:

It is unstable and readily undergoes change without detonating; it will react with

air or water or will spontaneously react under shock or friction as described in 40 CFR §261.23

(Waste Category D003).

(d)

Tox ic ity :

It is toxic, it leaches speciﬁc contaminants at an excessive rate as shown (formerly by

the EP Toxicity 40 CFR §261.24, and Appendix II and now) by the TCLP (40 CFR §261.24

and Appendix II), which has superseded the EP Toxicity test.

2. It is speciﬁcally listed in 40 CFR §261.11 Subpart C as a hazardous waste because of any of the

following:

(a) It exhibits any of the hazardous waste characteristics described above.

(b) It has been found to be fatal to humans in low doses or, in the absence of data on human

toxicity, it has been shown to be toxic to animals at speciﬁed low doses [40CFR §261.11 (a)2].

compounds and classes of compounds, i.e., lead and compounds not otherwise speciﬁed,

which have been determined by the EPA Administrator to be toxic, unless the Administrator

determines that the waste does not pose a present or potential hazard.) (40 CFR §261.111).

Wastes that are classiﬁed as hazardous solely because they are ignitable, reactive, or corrosive (but not

toxic) and contain no Appendix VIII constituents are exempt from those hazardous waste incinerator

regulations that relate to performance; however, they are still subject to waste analysis and closure

requirements of the regulations and must have a permit [40 CFR §264.340(b)].

Regulation of Incinerators

Incinerators burning refuse and other nonhazardous wastes are regulated under RCRA and the Clean

Air Act. The two sets of regulations were consolidated under RCRA as codiﬁed in 40 CFR §240 and for

medical wastes in §259. The regulation of both solid wastes, but especially of medical wastes, requires a

substantial amount of recordkeeping to track the wastes’ ultimate disposal or destruction.

Emission limits on nonhazardous waste incinerators are set on particulate, hydrogen chloride gas,

sulfur dioxide, volatile metals, semivolatile metals, nonvolatile metals, chlorodibenzodioxins, and chlo-

rodibenzofurans. The federal limits on emissions for nonhazardous waste incinerators are now substan-

tially equivalent to those for hazardous waste incinerators and are presented in the discussion of the

regulation of hazardous waste incinerators.

Physically, medical wastes are similar to general refuse, but they may be contaminated with pathogens.

They often also contain large quantities of polyvinyl chloride (PVC) and other chlorinated materials,

which form hydrogen chloride (HCl) on combustion. All of the pertinent environmental laws place limits

on the amount of HCl that may be emitted.

A major concern when operating an incinerator for medical wastes is maintenance of a sufﬁciently

high temperature for a sufﬁciently high solids and gas residence time to assure that the waste is sterilized.

Chlorodibenzo-dioxin and -dibenzofuran emissions are regulated to the lesser of the following two limits:

30 ng/m

or the amount determined to be safe on the basis of a site-speciﬁc risk assessment.

Hazardous wastes compromise the third set of wastes that are commonly incinerated. The treatment,

storage, and disposal of hazardous wastes are regulated under Volume 40, Part 264, Subtitle C of the

Resource Conservation and Recovery Act (RCRA). RCRA was passed by Congress in 1976 and amended

by the Hazardous and Solid Waste Amendments (HSWA) in 1984. Regulations that are new or have not