United States Solid Waste and
Environmental Protection Emergency Response
Agency (5305W)
EPA745-B-97-004
June 1997
&EPA
RCRA, Superfund & EPCRA
Hotline Training Module
Introduction to:
Toxics Release Inventory:
[Estimating Releases
(EPCRA §313; 40 CFR Part 372)
Updated June 1997
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DISCLAIMER
This document was developed by Booz-Allen & Hamilton Inc. under contract 68-WO-0039 to EPA. It is
intended to be used as a training tool for Hotline specialists and does riot represent a statement of EPA
policy. . ' .
The information in this document is not by any means a complete representation of EPA's regulations or
policies. This document is used only in the capacity of the Hotline training and is not used as a reference
tool on Hotline calls. The Hotline revises and updates this document as regulatory program areas change.
The .information in this document may not necessarily reflect the current position of the Agency. This
document is not intended and cannot be relied upon to create any rights, substantive or procedural,
enforceable by any party in litigation with the United States.
RCRA, Superfund & EPCRA Hotline Phone Numbers:
National toll-free (outside of DC area) (800) 424-9346
Local number (within DC area) (703)412-9810
National toll-free for the hearing impaired (TDD) (800)553-7672
The Hotline is open from 9 am to 6 pm Eastern Time,
Monday through Friday, except for federal holidays.
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TOXICS RELEASE INVENTORY:
ESTIMATING RELEASES
CONTENTS
1. Introduction
2. Regulatory Surnmary ... ........ : ............ . ......... . ........ ............ ... .............. .......... .............. . ........ 3
2.1 Release Reporting Requirements ....... ............................... . ......... ..... ................... .... 3
2.2 Analysis of Monitoring Data ..... ................. . ........... ........ ........ . ...... ......................... 4
2.3 Mass Balances ..... ..... ...... ............. ....... ............. ....... ....................... . ............ ....... ........... 7
2.4 Emission Factors ....... ..................... -. ..................... .'; .................... . ....... .... ....... . ............. 5
2.5 Engineering Calculations........ .............. .. ........ . ........................ . .......... ....; ........... ....... 10
2.6 Models and Computer Programs ..... .... ................. . ...... '. ................. ...... ......... , ........ ...14
2.7 Applicability of Estimating Methods ....... .............. , .................. . ....... .,.' ......... . .......... 15
2.8 Significant Figures... ................... ............'............ .................... . ......... 1........ ........... ..... 16
3. Module Summary..... ............... . .......... :...... .................. . ...................................... ................ 19
4. Review Exercises ........ . ........ ? ............. ........... .\.. ........ ............................................... . .......... 21
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TJRI: Estimating Releases - 1
1. INTRODUCTION
Section 313 of the Emergency Planning and Community Right-to-Know Act of 1986
(EPCRA) and the Pollution Prevention Act (PPA) of 1990 mandate the development
of a national inventory of releases of and other waste management activities
involving certain toxic chemicals into the environment. Under this section,
owners and operators of certain facilities that manufacture, process, or otherwise use
listed toxic chemicals must annually report releases and transfers of, and waste
management activities involving, these chemicals using the Form R or Form A.
Specifically, facilities must provide information on fugitive and point source air
emissions, water discharges, land disposal activities, and off-site chemical transfers.
Owners and operators of covered facilities must also include any on-site or off-site
recycling, energy recovery, or treatment of reportable chemicals. Completed forms
are then sent to both EPA and the designated state agency (i.e., the State Emergency
Response Commission (SERC)), through which the information is made available
to the general public and to Federal, state, and local government entities.
" * "' ' - -.''''
This module provides an overview of general techniques that owners and operators
of reporting facilities may use to estimate their toxic chemical releases. Although
the guidance on estimation techniques is provided primarily for calculating release
quantities, it can also be used to determine the amount of toxic chemical involved
in recycling, treatment, or energy recovery activities.. Hotline callers often need
assistance not only in determining if they have to'report, but also determining how
to report. This module will identify some of the resources that owners and
operators can use to estimate releases for Form R reporting. It also familiarizes
EPCRA Information Specialists with common estimation methods.
When you have completed this module you will be able to:
.Explain the basic release estimation techniques used to determine the
chemical quantities reported on the Form R -
Use those techniques, along with fundamental chemical; or physical
principles and.properties, to estimate releases of, and other waste
management activities involving, listed toxic chemicals
Convert units of mass, volume, and time
State the rules governing significant figures and rounding techniques
Reference the general and industry-specific guidance documents.
Use this list of objectives to check your knowledge of this topic after you complete
the training session.
1 ne information in this document is not by any means a complete representation of EPA's regulations or polici
but is an introduction used for Hotline training purposes.
.cies,
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2-TRI: Estimating Releases
The information in this document is not by any means a complete representation of EPA s regulations or policies,
but is an introduction used for Hotline training purposes.
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TRI: Estimating Releases - 3
2. REGULATORY SUMMARY
EPCRA §313 (40 CFR Part 372) requires owners and operators of certain
manufacturing facilities to annually report the quantities of listed toxic chemicals
released into the environment, transferred to other locations, recycled, treated, or,
burned for energy recovery. To complete the Form R, the owner or operator must
calculate or estimate the quantity of toxic chemicals involved in each of these waste
handling activities. Several techniques may be used in making this determination,
including analysis of monitoring data, mass balance calculation, use of emission
factors, and calculation based on engineering equations and judgment. All routine
and non-routine sources of releases and waste management activities, including
fugitive and point source air-emissions and liquid sources, should be considered
when estimating the quantity of toxic chemical released or managed as waste. This
module defines and provides examples of each estimation method, and identifies
the suggested applicability of each technique. EPA also prefers that estimates
reported on the Form R be rounded to no more than two significant figures, since
the accuracy of most estimates cannot justify the use of more than one or two
significant figures. This module, therefore, includes guidance on significant figures
and rounding techniques. Finally, this module discusses the general and industry-
specific guidance documents developed by EPA to aid reporting facilities in
completion of the Form R.
2.1 RELEASE REPORTING REQUIREMENTS
Owners/operators must use all readily available data concerning the reportable toxic
chemicals when estimating the releases and transfers of, and other waste
management activities involving, a toxic chemical. Monitoring quantities or
concentrations of toxic chemicals is not specifically required for the purpose of
completing the Form R, although such information can be extremely helpful in-
quantifying chemical activities. When relevant data are not readily available, the
reporting facility must make reasonable estimates of reportable toxic chemical
quantities using one or a combination of four basic techniques: analysis of
monitoring data, mass balance, emission factors, and engineering calculations. All
quantities calculated or estimated for reporting on the Form R must satisfy two *
requirements. First, all figures must be specific to the listed toxic chemical rather
than to the wastestream as a whole. Second, all quantities must be reported as
pounds per year. It may be necessary for the facility owner/operator to make
reasonable assumptions and manipulate available data to meet these criteria. The
methods for estimating releases and examples of such.calculations, are presented
throughout this module. It is important to note, however, that many types of
releases may require case-by-case analysis and simply cannot be covered in this
module.
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes:
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4-TRI: Estimating Releases
2.2 ANALYSIS OF MONITORING DATA
The most straightforward method of estimating releases for the Form R is to
calculate the amounts of listed toxic chemicals using actual measurements made
during the reporting year. Although monitoring data are not specifically required
under EPCRA §313, pertinent information may be coincidentally generated as part of
routine plant operations or to meet other environmental requirements. If
monitoring data are available for releases of a given toxic chemical, simple
calculations may yield an acceptable estimate. The facility purchasing department
may maintain inventory information. Waste disposal records may be available in
the accounts payable or environmental management offices. The facility may
generate monitoring data for permitting purposes (e.g., the National Pollutant
Discharge Elimination System and the National Emission Standards for Hazardous
Air Pollutant permits), or to demonstrate compliance with Clean Air Act emission
standards and Resource Conservation Recovery Act land disposal restrictions. All
dafa used in release calculations should be representative of the facility as it operated
during the reporting year. Sample results outside the normal range of operations
should be disregarded in favor of more accurate data from other sources or from
other testing periods. Whenever monitoring data are used as the primary tool in
estimating releases, the code "M" should be reported as the basis of estimate on the
Form R.
As stated previously, all data on the Form R must be reported as pounds per year,
but measurements may only be available for the wastestream by volume (e.g.,
gallons per hour) or as chemical concentrations (e.g., parts per million, milligrams
per liter). Thus, before monitoring data can be reported on the Form R, they may
have to be manipulated into the proper format. In such cases, it is necessary for the
owner/operator to convert the original data into pounds per year using density
information and other appropriate conversion factors from Estimating Releases and
Waste Treatment Efficiencies for the Toxic Chemical Release Inventory Form.
Example 1 illustrates how these conversions are made.
EXAMPLE 1 - DIRECT MEASUREMENT
<'.; i .,''
A wastewater stream containing five parts per million (ppm) lead is discharged to
the local publicly-owned treatment works (POTW). Monitoring data indicate an
average wastewafer flow rate of 10 gallons per minute. The density of the
wastewater is the same as that of water, 8.34 Ib/gallon. If the plant operates 24 hours
a day, 330 days a year, how much lead is discharged to the POTW in this
wastestream?
The information In this document is not by any means a complete representation ot bFA s regulations or policies,
but is an introduction used for Hotline training purposes.
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TRI: Estimating- Releases - 5
KNOWN QUANTITIES;
Concentration lead in wastewater = 5 ppm
Wastewater flowrate = 10 gallons/minute
; Hours of operation per day = 24 hours/day
Days of operation = 330 days/year
Density of wastewater = 8.34 pounds/gallon
STEP 1: Convert the measured volumetric flow rate from gallons/minute to
pounds/year. ':-.-
Convert the volumetric flow rate (V) to a mass flow rate:
mass flow rate (Ibs/min) = V (gal/min) x density (Ibs/gal)
= (10 gal/min)(8.34 Ibs/gal)
= 83.4 Ibs/min
Now, convert the mass flow rate to an annual mass flow rate:
annual mass flow rate (Ibs/yr) = (83.4 lbs/min)(60 min/hr)(24 hr/day)(330
days/yr) ,
= 3.96 x 107 Ibs wastewater discharged per year
STEP 2: Using concentration information, determine the quantity of lead
discharged in wastewater per year.
5 ppm lead = 5 parts lead per 1 million parts wastewater
= 5 Ibs lead per 1 million Ibs wastewater
(3.96 x 10? Ibs ww discharged/year)(5 Ibs lead/1 million Ibs ww)
= 198 Ibs lead discharged per year
ANSWER: Accounting for significant figures as discussed in Section 2.7 of this
rnodule, an estimated 200 pounds of lead are discharged annually in the
wastewater transferred to the POTW. ,
In addition t'o manipulating data to reflect the proper units, many manufacturing
facilities must first calculate the amount of toxic chemical in the wastestream. To do
this, the weight of the wastestream, derived from monitoring data, should be
multiplied by the mass fraction of the toxic chemical in that wastestream. The
owner or operator may again have to convert associated units, or may need to
employ basic chemical or physical equations such as the Charles' Law to derive an
appropriate figure. Example 2 details this type of calculation.
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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6-TRI: Estimating Releases
EXAMPLE 2-DIRECT MEASUREMENT
Measurements are taken at the oxychlorination vent of a plant producing
dichioroethylene (DCE) under normal operating conditions. The concentration of
DCE in the gas is 0.22 grams/cubic meter. Based on the size of the vent and the
speed of the waste gas exiting the vent, the owner has calculated the flow rate of the
exiting gas at 59,400 ftVhr. The facility is in operation 2,000 hours each year.
Calculate the annual releases of DCE from this vent.
KNOWN QUANTITIES:
Gas flow rate = 59,400 cubic feet/hour
Concentration DCE in gas = 0.22 grams/cubic meter
Operating hours = 2,000/year
STEP 1: Convert the DCE concentration from metric units (grams per cubic meter)
to English units (pounds per cubic foot).
Measured DCE concentration = 0.22 g/m3
Conversion factors: 1 pound = 454 grams
1 ft3 = 0.028m3
DCE concentration = (0.22 g/m3)(l lb/454 g)(0.028 mVft3)
= 1.36 x ID"5 Ibs DCE per cubic foot of vent gas
STEP 2: Determine the quantity of DCE released per hour.
DCE emission rate
= DCE cone, in waste gas (lbs/ft3) x waste gas flow rate (ftVhr)
= (1.36 x 10-5 ibs DCE/ft3 gas)(59,400 ft3 gas/hr)
= 0.808 pounds DCE released per hour
STEPS: Calculate annual releases of DCE. -
Annual DCE emissions
= DCE flow rate (lbs/hr) x operating time (hr/yr) '
= (0.808 Ibs DCE/hr operation)(2,000 hr of operation/year)
= 1,600 Ibs DCE/year
AMS-WER: 1,600 pounds of DCE were released during the reporting year from the
oxychlorination vent.
The information in this document is not by any means a complete representation of EPA s regulations or policies,
but is an introduction used for Hotline training purposes.
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TRI: Estimating Releases - '7
2.3 MASS BALANCES
The second estimation technique takes into account the law of conservation of
mass, and provides a means of accounting for all the inputs and outputs of a
particular toxic chemical throughout a facility or process. Since mass can be neither
created nor destroyed, the amount of chemical entering the system must equal the
amount of chemical exiting the system in one form or another. The general
equation .for mass balance is:
Input + Generation = Output + Amount Reacted + Accumulation
For the purposes of Form R reporting, input is the total amount of toxic chemical
available at the beginning of the year plus the amount purchased during the year.
Generation is the amount manufactured at the facility. Output is the amount,of
toxic chemical that left the facility as product, was released on site, or was transferred
off site as a waste for treatment/recycling, or disposal. Amount reacted is the
amount of the toxic chemical that was converted into another chemical on site, such
as in waste treatment or as a reactant. Accumulation is the amount of the chemical
left in inventory at the end of the calendar year. Example 3 illustrates how these
pieces can be used in mass balance calculations to estimate releases for the Form R.
The code "C" should be reported as the basis for estimate on Form R for all
quantities derived from mass balance calculations.
EXAMPLE 3 - MASS BALANCE
A specialty steel manufacturer processes nickel in production operations. In a year,
the facility produced 24,000 pounds of product containing 20 percent nickel (Ni) by
weight. During the calendar year, 8,000 pounds of nickel were purchased, and
inventory records show that 4,000 pounds of nickel were left over from the
preceding year. The process generated 10,000 pounds of scrap containing 10 percent
nickel by weight; this waste is sent off site for recycling. At the end of the calendar
year, 2,000 pounds of nickel were left in inventory. An unknown amount of nickel
was disposed of'off site in the facility's solid waste. Using mass balance calculations,
estimate this unknown quantity. . ,
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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8 - TRI: Estimating Releases
KNOWN QUANTITIES;
Amount of product = 24,000 pounds
Concentration Ni in product = 20 percent by weight
Amount Ni purchased = 8,000 pounds
Initial Ni inventory = 4,000 pounds
Amount of scrap = 10,000 pounds by weight
Concentration of Ni in scrap = 10 percent
Final inventory = 2,000 pounds
STEP 1: Input = Amount Ni Purchased + Amount Ni in Inventory
= 8,000 Ibs + 4,000 Ibs
«12,000 IbsNi
STEP 2: Output = (Ni in product) + (Ni in scrap) + (Ni in solid waste)
= 20 wt%(24/000"lbs product) + 10 wt%(10/000 Ibs scrap) + X Ibs in
solid waste
= 5,800 Ibs Ni + X Ibs Ni in solid waste
STEP 3: Accumulation = Amount left in inventory
= 2,000 Ibs Ni
STEP 4: No nickel is reacted or generated at the facility in this scenario. (These
terms are generally not relevant to mass balances for metals.)
STEPS: Complete the mass balance equation, solving for X.
Input + Generation = Output + Amount Reacted + Accumulation
12,000 Ibs + 0 = 5,800 Ibs + X + 0 + 2,000 Ibs
X = 4,200 Ibs Ni
AMSWER: Accounting for significant figures, 4,200 pounds of nickel are sent off-
* site for disposal.
* * * * *
2.4 EMISSION FACTORS
An emission factor is an average value that describes the quantity of a chemical
released to the atmosphere as a function of the specific process or equipment used at
a facility. Emission factors are frequently expressed as a ratio of chemical released to
chemical throughput or amount of product produced. Depending on the exact
measurements being compared, emission factors can be expressed in various units
(e.g., pounds of chemical released per pound of product output, pounds of chemical
released per hour of operation, or pounds of chemical released per pound of
chemical circulating in the system).
The Information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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TRI: Estimating' Releases - 9
Emission factors are derived from monitoring data on chemical operations. To
calculate an emission factor, data are collected on both the amount of toxics being
processed through the system and the amount of chemical being released. From
these data, a ratio (emission factor) is created. Emission factors are based on the
assumption that similar operations will have approximately the same ratio of
releases to throughput of a given chemical, even though the operations may be on a
different scale. Factors have been developed for specific volatile organic compounds
(VOCs), particulates, and some specific toxic chemicals. These commonly used
emission factors are found within the guidance document Compilation of Air
Pollutant Emission Factors (AP-42). This document can be downloaded through the
Clearinghouse for Inventories and Emission Factors (CHIEF) bulletin board system
by calling (919) 541-5742, or may be downloaded from the Technology Transfer
Network (TTN) on the World Wide Web. AP-42 is also available through Fax
CHIEF at (919) 541-0548.
Example 4 employs a chemical-specific emission factor to estimate releases from a
process. Facilities using this estimation technique would choose code "E" as the
basis of estimate on Form R. .
EXAMPLE 4 - EMISSION FACTOR
Air emissions from the blast furnace at a primary lead smelting facility are
controlled by a fabric filter system. This specific industry is.discussed in section 7.6 of
the document Compilation of Air Pollutant Emission Factors (AP-42). Data listed in
this section include an emission factor for uncontrolled particulate releases from a
blast furnace of 361 pounds per ton of lead produced. A particulate removal
efficiency range of 95-99 percent is also given for fabric filter air pollution control
devices, which are used in many primary lead smelting operations.
Calculate the total releases of lead from the particulate emissions, assuming, that the
particulates are 30.7 percent lead, that 31,500 tons of lead are produced-annually, and
that a fabric filter control device is used.
KNOWN QUANTITIES:
Particulate emission factor = 361 pounds of particulate/ton of lead (Pb) produced
Efficiency range of fabric filter control device = 95-99%
Concentration of lead in particulate = 30.7 percent'dry weight
Annual production of lead = 31,500 tons/year
STEP 1: Adjust uncontrolled emission factor to account for air pollution control
device. ,
Adjusted emission factor . ,
= original emission factor (Ibs/ton) x average efficiency of fabric filters (%)
= 361 Ibs total particulates/ton Pb produced x 3% uncontrolled emissions
The information, in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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10 -TRI: Estimating Releases
= 10.83 Ibs uncontrolled particulates released /ton Pb produced
STEP 2: Calculate poundage of uncontrolled particulates released per year
Uncontrolled particulate emission rate
= adjusted emission factor (Ibs/ton) x amount produced per year (tons/year)
= (10.83 Ibs/ton Pb produced)(31/500 tons Pb produced/year)
= 341,145 Ibs uncontrolled particulates released/year
STEP3: Calculate quantity of lead in particulate emissions.
Uncontrolled lead emissions
= annual particulate emission rate (Ibs/yr) x percent Pb in particulates
= (341,145 Ibs particulates/year)(30.7% Pb in particulates)
= 104,731.5 Ibs Pb released/year
ANSWER: Accounting for significant figures, 105,000 pounds of lead are estimated to
be released to air annually as particulates from the facility's blast furnace.
* * * *
2.5 ENGINEERING CALCULATIONS
1
Specific data required to estimate releases will sometimes be unavailable or
unreliable. Sometimes parameters related to emissions cannot be directly
measured. In these situations, estimates may be based on best engineering
judgment or calculations. For example, facility operators may use physical and
chemical properties of the materials involved, equipment design information, or
emission information from similar processes to estimate the releases of a toxic
chemical. Engineering calculations are generally used to supplement the
information needed for one of the other release estimation techniques. EPA
guidance indicates that estimates based on nonchemical-specific factors should be
considered as engineering calculations with the code of "O" (Question 364, EPCRA
Section 313 Questions and Answers, November 1997). Use of unpublished or
facility-specific factors would also fall under the category of engineering calculations.
The following examples illustrate engineering calculations that incorporate some of
the concepts, such as air emission factors and monitoring data, discussed previously
in this module.
EXAMPLE 5 - ENGINEERING CALCULATION
A chemical plant uses benzene in its production operations. Benzene is a light
liquid with a vapor pressure greater than two pounds per square inch (psia). Process
equipment at the facility includes six pipe valves, three open-end valves, four
flanges, two pumps, one compressor, and one pressure-relief valve. During the
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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TRI: Estimating Releases - 11
reporting year, the facility operated 24 hours a day for a total of 250 days.
Estimate fugitive emissions to air from equipment leaks using emission factors
KNOWN QUANTITIES: -
Operating hours = 24 hours/day
: Operating days = 250 days/year
STEP 1: Compile appropriate emission factors for the process units.
All equipment is subject to leakage, especially at places such as connection
points, seals, and valves. The quantity of chemical released in this
manner is dependent upon the quality and frequency of equipment
maintenance. Poorly maintained equipment has higher leakage rates and ,
higher emission factors than well-maintained equipment. To estimate the
releases due to leakage, we have chosen to use average fugitive emission
factors for the synthetic organic chemicals manufacturing industry
, (SOCMI). These emission factors represent the quantity of chemical
released to air from leaks in process components such as valves, seals, and
flanges. The following SOCMI emission factors may be found in
Apppndiy D of Estimating Releases and Waste Treatment Efficiencies for
the Toxic Chemical Release Inventory Form.
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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12-TRI: Estimating Releases
SQCMI EMISSION FACTORS (as listed in Appendix D);
6 Pipe valves (in light liquid service) = 0.016 pounds/hour each
3 Open-end valves = 0.0037 pounds/hour each
4 Flanges = 0.0018 pounds/hour each
2 Pump seals (in light liquid service) = 0.11 pounds/hour each
1 Compressor seal = 0.50 pounds/hour
1 Pressure-relief valve = 0.23 pounds/hour
STEP 2: Each emission factor above represents pounds of leakage per unit.
Since some components are present at several points in the process, it is
necessary to calculate the aggregate emission factor.
Total fugitive emission factor from process
- (6 x 0.016) + (3 x 0.0037) + (4 x 0.0018) + (2 x 0.11) + (0.50) + (0.23)
= 1.064 Ibs/hr
STEP 3: Calculate annual releases of benzene.
Annual emission rate
= (1.064 lbs/hr)(24 hr/day)(250 days/year)
= 6,385.8 Ibs/year
ANSWER: Rounding off to 2 significant figures, 6,400 pounds of benzene are
released to air annually in fugitive emission leaks from process
equipment at the chemical plant.
*****
When making engineering calculations, the facility owner or operator will often
incorporate some monitoring data, and it may be unclear which code should be
reported on the Form R as the basis of the estimate. In most cases, analysis of
monitoring data primarily involves manipulation of direct measurements to extract
data in the proper units or on a particular chemical. For quantities derived in this
manner, "M" is the estimate code that should be used. Alternatively, when the
focus of the estimation is on chemical or physical principles, regardless of the use of
measured data, the basis of estimate should be reported as "O." The following
scenario provides an example of engineering calculations supplemented by
monitoring data.
EXAMPLE 6 - ENGINEERING CALCULATION
A facility had an episodic event during which a wastestream containing nitric acid
(HNOs) fell from a typical pH of 6.0 to an average pH of 1.6. During the 10-minute
episode, the wastewater was discharged to a river at a rate of 106 gallons per minute.
Estimate the quantity of HNOs discharged to the river during this episodic release.
KNOWN QUANTITIES:
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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TRI: Estimating Releases - i3
pH of discharge = 1.6
Length of episode = 10 minutes
Rate of discharge = 106 gallons/minute
STEP 1: Explain the chemical relationship between hydrogen ion,
concentration [H+] and the nitric acid concentration [HNOs]. (The symbol
,[H+] indicates hydrogen ion concentration, and [HNOs] represents nitric
acid concentration, both expressed in moles/liter.)
Nitric acid dissociates according to the equation:
[HNOs] <- ------- > [H+] + [NOsI
Although the equation indicates an equilibrium between HNOs, hydrogen
ions, and nitrate ions, since HNOs is a strong acid, the equilibrium
actually lies far to the right, this means that in a solution, most of the
acid will readily dissociate into the individual ions and thus, the total
molar concentration of nitric acid is equal to the hydrogen ion
concentration.
STEP 2: Explain the chemical relationship between pH and hydrogen ion
concentration.
. pH is a logarithmic measure of the hydrogen ion concentration in a
solution. As the pH drops, the solution becomes more acidic. As the pH-
rises, the solution becomes more basic. The mathematical relationship is:
= -logio[H+] '
. [H+] = 10-PH = [HNOs]
STEP 3: .Calculate the wastestream concentration of nitric acid in pounds per
gallon using a pH of 1.6.
[HNOs] = 10'1-6 = 0,025 moles HNOs per liter
Molecular weight: 63.01 grams HNOs per mole
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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14-TRI: Estimating Releases
Conversion factors: 3.784 liters per gallon
1000 grams per kilogram
2.205 pounds per kilogram
[HNOsJinlbs/gallon
= (0.025 mol/L)(63 g/mol)(3.784 L/gal)(l kg/1000 g)(2.205 Ibs/kg)
= 0.0131 Ibs/gal
Mote: Although the calculation above is presented for clarification, Table 1 of
Estimating Releases for Mineral Acid Discharges Using pH
Measurements can be used to directly match pH values with [HNOs]
in pounds per gallon. Information is also provided for other mineral
acids.
STEP 4: Determine total quantity of nitric acid released during the reporting year.
Release of HNOs during the episode
= (Effluent flow rate) (HNOs in effluent) (Flow duration)
= (106 gal/min)(0.0131 lbs/gal)(10 min)
= 13.9 Ibs/episode
ANSWER: If this is the only episode during the reporting year, the facility should
report a total annual discharge of HNOs to the river of 14 pounds (after
rounding to significant figures). Although a small amount of nitric
acid is released in wastewater at pH 6, the Form R instructions (p. 25)
state that a facility can report "0" for discharges of neutralized mineral
acids (pH 6 or above).
2.6 MODELS AND COMPUTER PROGRAMS
Various models and computer programs may be used by facilities to estimate
releases or waste generation sources. These models and programs include, but are
not limited to, CHEMDAT8, TANKS, TSCREEN, and WATERS. These four models
and programs are specifically mentioned in EPA's industry-specific guidance for
newly added facilities under the Toxic Release Inventory phase 2 expansion.
Facilities can download all four models and programs, along with a corresponding
users manual, from the World Wide Web.
i
CHEMDAT8
Consisting of several analytical models assembled into a spreadsheet, CHEMDAT8
estimates organic compound emissions via various pathways from water and waste
management units. Facilities may also use the models to estimate the magnitude of
site air emissions for regulatory purposes. Several area emission sources are
incorporated into the analytical models. Area emission sources include non-aerated
The Information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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TRI: Estimating Releases - 15
impoundments (e.g., surface impoundments and open top wastewater treatment
tanks),, aerated impoundments (e.g., Surface impoundments and wastewater
treatment tanks), disposal impoundments (e.g., non-aerated disposal
impoundments), land treatment, and landfills.
TANKS '" " '. '
The TANKS program estimates organic chemical emissions from several types of
storage tanks on an annual or partial year basis. The program relies on a chemical
database of over 100 organic liquids arid a meteorological database which includes
over 250 cities within the United States. The calculations within the program are
performed according to AP-42. Facilities within SIC code 5171 (i.e., petroleum bulk
storage facilities) and other facilities storing EPCRA Section 313 toxic chemicals in
underground and aboveground storage tanks may benefit from using TANKS.
TSCREEN "','' ...'''. .
The TSCREEN model which includes the TSCREEN computer program used in
conjunction with the EPA document entitled Workbook of Screening Techniques
for Assessing Impacts of Toxic Air Pollutants (Revised. 1992a1. estimates emissions
from tailing piles, as well as other types of possible releases. Facilities within SIC
code 10 (i.e., metal mining facilities) may benefit from using the TSCREEN model.
WATERS
WATERS, a DOS computer program, estimates the fate of organic compounds in
various wastewater treatment units, including collection systems, aerated basins,
and other units. The computer program links treatment units to form a treatment
system, considers recycling among units, and generates and saves site-specific
compound properties. .
2.7 APPLICABILITY OF ESTIMATING METHODS
Although any technique described in this module can be used to estimate releases
for the Form R, all methods may not be applicable to or appropriate for all types of
releases. The approach selected will be based on the type of release involved (i.e.,
the medium to which the chemical is released), and to a lesser extent, the specific
toxic chemical being released.
Fugitive Air Emissions
Measurement data on fugitive air emissions will rarely be available. Furthermore,
fugitive emissions from most sources are small compared to the total amount of
chemical handled during the year, and these losses are difficult to estimate.
The information in this document is not by any means a complete representation ot fcJfA s regulations or policies,
but is an introduction used for Hotline training purposes.
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16-TRI: Estimating Releases
accurately if mass balance techniques are attempted. For these reasons, the use of
emission factors and engineering calculations are the most widely used method for
determining fugitive releases to air. Emission factors are available for many specific
chemicals/ processes, and types of equipment. Of course, if these data are
unavailable for the particular chemical or unit involved, another estimation
technique must be chosen.
Point Source Air Emissions
Since point source air emissions are enclosed, these releases are more likely than
fugitive emissions to have been measured and quantified. Analysis and
manipulation of monitoring data (e.g., chemical concentrations and exhaust gas
flow rates) is thus a common method for estimating these types of releases. If
monitoring data are unavailable or do not represent normal operations at the
facility, emission factors may be used. When these approaches are not possible,
point source release estimates can be based on mass balance equations. As with
fugitive emissions, however, the toxic chemical quantities released may be
insignificant when compared to the total throughput at the facility, and mass
balance techniques may provide somewhat inaccurate estimates.
Releases to Water
Many of the listed toxic chemicals under EPCRA §313 are also subject to a variety of
other federal, state, and local environmental laws. To ensure compliance with these
programs, water discharges are often monitored, and releases can be calculated using
these data. If no monitoring is conducted, the facility can use either mass balance
calculations or engineering calculations. The mass balance technique is an option
for water releases if there are not too many input and output streams.
Releases to Land
Land disposal of waste is typically regulated under RCRA, and requires the
preparation and maintenance of shipment records. These records or manifests
should contain information on the quantity and type of waste transferred off site, as
well as the location to which the wastes were sent. For purposes of hazardous waste
identification, the concentration of certain chemicals in the waste may have been
measured. Mass balance calculations or monitoring data analysis can be used to
estimate releases when appropriate records are available.
2.8 SIGNIFICANT FIGURES
,|n" J *
Most measurements of any physical quantity will have some degree of error. The
size of this errojf will depend on the sensitivity of the tool used to take the
measurement. For example, if a rock weighing exactly 479.555 pounds is measured
on a scale that is calibrated in 1-pound intervals, the scale would read that the rock
The information in this document is not by any means a conroletereprepntationof EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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TRI: Estimating Releases - 17
weighed 480 pounds. If the rock was then measured on a scale calibrated in 0.1-
pound intervals, the weight would then be displayed as 479.6 pounds, the more
sensitive the measuring instrument, the more digits (significant figures) the
instrument will use to express the measured quantity.
To determine ,the number of significant figures in a given value, we count the
digits. All digits other than zero are always considered significant. A zero may. or
may riot be considered significant, depending on its position in the value relative to
other digits and the decimal point. The following rules apply to zeros:
A zero is significant if it is both preceded and followed by a nonzero digit.
According to this rule, the value 10.203 has five significant figures, and 1.002
has four significant figures. V >" :
A zero is not significant if it is not preceded by a nonzero digit. For example,
the first 0 in the value 0.123 is not significant, nor are the zeros in 0.0001.
These zeros are necessary only to indicate where the decimal point lies.
Final zeros to the right of the decimal point are significant. Thus, 1.000 has
four significant figures, and 0.010 has two significant figures.
Final zeros in a whole number may or may not be significant. If the
number is followed by a decimal point, as in 1200., all four digits are counted
as significant. If no decimal point is included, however, the value 1200
would contain only two significant figures.
When completing the Form R, EPA requires a degree of accuracy no greater than
two significant figures (53 PR 4514;.February 16,1988). Even though calculators may
be used .to make release calculations and estimates providing results containing
many digits, such estimates should be rounded off to two significant digits in ordfer
not to imply false accuracy of the reported estimate. If more than two significant
figures are available, the facility may use its best reasonable estimate or degree of
accuracy with which it feels comfortable (within reason). If the facility does not
release a toxic chemical to a specific environmental media or off-site location and
there was no possibility of a release, NA should be reported.. If a release to a specific
medium or off-site location could have occurred, but either did not occur or the
.annual aggregate release is less than 0.5 Ibs., zero should be reported. A facility
reporting zero releases must provide a basis of estimate on the Form R. In sections 5
and 6 of the Form R, a facility can avoid the issue of significant figures altogether by
reporting using range codes (rather than using a specific number1) for releases
between 1 and 1,000 pounds. ~
Before rounding reported quantities, the following rules should be consulted:
If the first digit to be dropped is greater than 5, the last significant figure
should be rounded up. If the digit to be dropped is less than 5, the number
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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18-TRI: Estimating Releases
should be rounded down. According to these rules, 1.62 would be rounded
down to 1.6, while 1.67 would be rounded up to 1.7.
When the first digit to be dropped is 5, always round to the nearest even
number. If the value 1.35 is rounded to two significant figures, the reported
value would be increased to 1.4, but if the value 1.25 is rounded to two
significant figures, the reported value would be decreased to 1.2. The value
0.5 would be rounded down to 0.
In performing a calculation of two or more steps, it is desirable to retain additional
digits for intermediate answers. This ensures that small errors from rounding do
not appear in the final result. Therefore, reported quantities should be rounded
only after all calculations have been made.
ADDING AND SUBTRACTING
When adding and subtracting measured quantities, we should give the same
number of decimal places in the answer as there are in the measurement with the
least number of decimal places. The following example illustrates this technique:
A test tube is weighed on a scale that is calibrated in 0.001 pound intervals.
According to this scale, this test tube weighs 1.225 pounds. Water is weighed on a
scale that is calibrated in 1-pound intervals. A 5-pound sample of the water is placed
in the test tube. If these two quantities were added together, the answer would be
6.225 pounds; however, the final quantity can only be as accurate as the least precise
piece of equipment. Since the scale was calibrated in 1-pound intervals, the answer
must be as well. Therefore, using significant figures, the answer is 6 pounds.
MULTIPLYING AND DIVIDING
When multiplying or dividing measured quantities, we should give as many
significant figures in the answer as there are in the measurement with the least.
number of significant figures. The following examples illustrate this technique:
The area of a rectangular piece of wood would be calculated by multiplying the
piece's width by its length. The width is measured to be 7.9 feet and the length is
measured to be 4.334 feet. Therefore, the area would be calculated to be 34.2386
square feet. The answer seems to have the precision to the 0.0001 feet; however, the
data's precision does not support the answer's precision. The answer needs to be
rounded off to the number of significant figures in the least precise quantity, so the
answer using significant figures is 34 square feet.
Trie information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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TRI: Estimating Releases - 19
3. MODULE SUMMARY
Having completed this module you should now have a basic understanding of the
four techniques used to estimate toxic chemical releases to be reported on the Form
R. The first method covered was the analysis of monitoring data obtained
throughout the reporting year; This technique can be very helpful when estimating
air-emissions, releases to water, and releases to land. The second technique
discussed was mass balance. A mass balance provides a means of accounting for all
the inputs and outputs of a particular toxic chemical throughout a facility or process.
The third technique, as described in the module, was emission factors which are
derived from monitoring data on chemical operations and used primarily to
estimate air emissions. The last technique discussed was engineering calculations.
Engineering calculations are generally used to. "fill in" information needed for one
of the other release estimation techniques.
In addition to being familiar with release estimation techniques, you should also be
aware of the rules governing significant figures and rounding techniques. EPA
requires that release and transfer estimates on the Form R be reported with a degree
of accuracy no greater than two significant figures, but facilities may use estimates
with a higher degree of accuracy. It is also important to remember.that rounding
should occur only after all calculations have been completed.
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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2Q-TRI: Estimating Releases
olicies.
The information in this document is not by any means a complete representation of EPA's regulations or polici
but is an introduction used for Hotline training purposes.
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TRI: Estimating Releases - 21
4. REVIEW EXERCISES
The exercises in this section are designed to help you check your knowledge of the
material in this module. Use any reference materials you need to answer the
questions. Provide complete citations and write your answers in paragraph form.
EXERCISE1
Determine the number of significant figures in each quantity and round to two
significant figures for Form R purposes. What is EPA's policy on significant figures
for the Form R?
1. 2400
2. 2701
'3. 23.003 ' ' . -
4. 0.00305 . . ' ,
5. 235.5 /
EXERCISE2
Convert from one unit to another. Conversion factors are listed in Estimating
Releases and Waste Treatment Efficiencies. Show all work and be sure to round the
result off to two significant figures^ .
1. 411 in = ? meters '
2. 5,150 m3 = ? U.S."gallons
3. 5.7 x ID'3 Ibs. = ? mg . - '
4. 125^0 mm Hg = ? psia
5. 203mph = ?ft/s ' . . , .
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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22 -TRI; Estimating Releases
EXERCISES
Estimating Releases and Waste Treatment Efficiencies contains chemical and
physical properties of §313 toxic chemicals. Using this resource, answer the
following questions.
All data are found in Appendix B.
1. The specific gravity and density of nitrogen mustard. (Follow the
directions on page B-3.)
2. The ambient state of aniline.
3. The molecular weight of benzidine.
4. The vapor pressure of chloroprene. At what temperature?
5. For chemicals newly listed on the EPCRA §313 toxic chemical list, what
resources are available for determining the chemical/physical properties
of the toxic chemicals?
EXERCISE 4
Determine which release estimation technique would generally be applicable in the
following situations. (Note: Depending on case-specific circumstances and
information, any method may be selected for a given situation.) Briefly discuss why
your choice would be selected, and list possible sources of additional information
which may be helpful in making release estimates.
1. Copper is a component of the plating and other process baths at Ebbs
electroplating facility. Copper exits the facility only in the finished product
(e.g., castings) and as a wastewater discharge.
2. A roll coating facility sends a listed hazardous waste generated during
"dry" coating cleanup operations to an off-site landfill. In compliance
with RCRA regulations, a manifest always accompanies the waste
shipment.
3. Release estimates must be made for a one-time accidental spill of a toxic
chemical in the parking lot at Suzie's Colors and Fabrics.
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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TRI: Estimating; Releases - 23
EXERCISES
On July 27, 1998, the operator of a petroleum bulk storage facility pumps an aviation
gasoline liquid mixture containing toluene out on an external floating roof tank
(EFRT). The level of aviation gasoline in the EFRT drops five feet below its original
level once the operator finishes pumping, leaving gasoline exposed on the tank
walls. The residual aviation gasoline evaporates from the tank walls into the
surrounding air., ^
1. Is the petroleum bulk storage facility required to file a Toxic Release Inventory
(TRI) report for the amount of toluene released from the residual aviation gasoline
if the facility repackages 60,000 gallons of aviation gasoline during reporting year
(RY) 1998? Explain how you arrived at your answer. [Note: For question 1., assume
the petroleum bulk storage facility does not have access to any specific concentration
data regarding EPCRA Section 313 chemicals.] -
2. Assume the petroleum bulk storage facility exceeds the 25,000 pound process
threshold for toluene during RY 1998. How would the evaporative loss of toluene
originating from the exposed EFRT walls be reported on the facility's Form. R report
due July 1,1999?
The information in this document is not by any means a complete representation of EPA's regulations or polici
but is an introduction used for Hotline training purposes.
icies,
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24-TRI: Intimating Releases
EXERCISE 6
Using the document Compilation of Air Pollutant Emission Factors (AP-42),
determine the following emission factors.
1. Releases of ammonia from a carbon dioxide regenerator used at synthetic
ammonia plants.
2. Emissions of tetrachloroethylene, a volatile organic compound (VOC), *
from processing southern pine wood in a plywood veneer dryer during
plywood manufacturing operations.
3. Uncontrolled fugitive lead particulate emissions from secondary lead
smelting operations.
4. Uncontrolled releases of lead from the manufacturing of Portland cement
using kilns in the wet process.
5. Emissions resulting from the cleaning of a tank truck which contained
tetrachloroethylene. (You may need to use your Common Synonyms
booklet.)
The information in this document is not by any means a complete representation of EPA's regulations or policies,
but is an introduction used for Hotline training purposes.
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