[Federal Register Volume 67, Number 128 (Wednesday, July 3, 2002)]
[Proposed Rules]
[Pages 44672-44713]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-15873]



[[Page 44671]]

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Part II





Environmental Protection Agency





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40 CFR Part 63



National Emission Standards for Hazardous Air Pollutants: Mercury 
Emissions From Mercury Cell Chlor-Alkali Plants; Proposed Rules

  Federal Register / Vol. 67, No. 128 / Wednesday, July 3, 2002 / 
Proposed Rules  

[[Page 44672]]


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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 63

[FRL-7236-6]
RIN 2060-AE85


National Emission Standards for Hazardous Air Pollutants: Mercury 
Emissions From Mercury Cell Chlor-Alkali Plants

AGENCY: Environmental Protection Agency (EPA).

ACTION: Proposed rule.

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SUMMARY: This action proposes national emission standards for hazardous 
air pollutants (NESHAP) for mercury cell chlor-alkali plants. The 
proposed standards would limit mercury air emissions from these plants. 
The proposed standards would implement section 112(d) of the Clean Air 
Act (CAA) which requires all categories and subcategories of major 
sources and area sources listed in section 112(c) to meet hazardous air 
pollutant emission standards reflecting the application of the maximum 
achievable control technology (MACT). The proposed standards would 
reduce nationwide mercury emissions from these sources by about 4,100 
kilograms per year (kg/yr) (9,100 pounds per year (lb/yr)) from the 
levels allowed by the existing mercury NESHAP.
    Mercury is a neurotoxin that accumulates, primarily in the 
especially potent form of methylmercury, in aquatic food chains. The 
highest levels are reached in predator fish species. Mercury emitted to 
the air from various types of sources (usually in the elemental or 
inorganic forms) transports through the atmosphere and eventually 
deposits onto land or water bodies. When mercury is deposited to 
surface waters, natural processes (bacterial) can transform some of the 
mercury into methylmercury that accumulates in fish. The health effect 
of greatest concern due to methylmercury is neurotoxicity, particularly 
with respect to fetuses and young children.

DATES: Comments. Submit comments on or before September 3, 2002.
    Public Hearing. If anyone contacts the EPA requesting to speak at a 
public hearing by July 23, 2002, a public hearing will be held on 
August 2, 2002.

ADDRESSES: Docket. Docket No. A-2000-32 contains supporting information 
used in developing the proposed standards for the mercury cell chlor-
alkali plant source category. The docket is located at the U.S. EPA, 
401 M Street, SW., Washington, DC 20460 in Room M-1500, Waterside Mall 
(ground floor), and may be inspected from 8:30 a.m. to 5:30 p.m., 
Monday through Friday, excluding legal holidays.

FOR FURTHER INFORMATION CONTACT: Mr. Iliam Rosario, Metals Group, 
Emission Standards Division (C439-02), U.S. EPA, Research Triangle 
Park, North Carolina 27711, telephone number: (919) 541-5308, 
facsimile: (919) 541-5600, electronic mail address: 
[email protected].

SUPPLEMENTARY INFORMATION:
    Comments. Comments and data may be submitted by electronic mail (e-
mail) to: [email protected]. Electronic comments must be submitted 
as an ASCII file to avoid the use of special characters and encryption 
problems and will also be accepted on disks in WordPerfect[reg] format. 
All comments and data submitted in electronic form must note the docket 
number: Docket No. A-2000-32. No confidential business information 
(CBI) should be submitted by e-mail. Electronic comments may be filed 
online at many Federal Depository Libraries.
    Commenters wishing to submit proprietary information for 
consideration must clearly distinguish such information from other 
comments and clearly label it as CBI. Send submissions containing such 
proprietary information directly to the following address, and not to 
the public docket, to ensure that proprietary information is not 
inadvertently placed in the docket: OAQPS Document Control Office 
(C404-02) Attention: Iliam Rosario, Metals Group, Emission Standards 
Division, U.S. EPA, Research Triangle Park, NC 27711. The EPA will 
disclose information identified as CBI only to the extent allowed by 
the procedures set forth in 40 CFR part 2. If no claim of 
confidentiality accompanies a submission when it is received by the 
EPA, the information may be made available to the public without 
further notice to the commenter.
    Public Hearing. Persons interested in presenting oral testimony or 
inquiring as to whether a hearing is to be held should contact Cassie 
Posey, telephone number: (919) 541-0069. Persons interested in 
attending the public hearing must also call Cassie Posey to verify the 
time, date, and location of the hearing. The public hearing will 
provide interested parties the opportunity to present data, views, or 
arguments concerning the proposed emission standards.
    Docket. The docket is an organized and complete file of all the 
information considered by the EPA in rule development. The docket is a 
dynamic file because material is added throughout the rulemaking 
process. The docketing system is intended to allow members of the 
public and industries involved to readily identify and locate documents 
so that they can effectively participate in the rulemaking process. 
Along with the proposed and promulgated standards and their preambles, 
the contents of the docket will serve as the record in the case of 
judicial review. (See section 307(d)(7)(A) of the CAA.) The regulatory 
text and other materials related to this rulemaking are available for 
review in the docket or copies may be mailed on request from the Air 
Docket by calling (202) 260-7548. A reasonable fee may be charged for 
copying docket materials.
    World Wide Web Information. In addition to being available in the 
docket, an electronic copy of today's proposed rule will also be 
available through EPA's World Wide Web site. Following signature, a 
copy of the rule will be posted on our policy and guidance page for 
newly proposed or promulgated rules: http://www.epa.gov/ttn/oarpg. The 
web site provides information and technology exchange in various areas 
of air pollution control. If more information regarding the web site is 
needed, call our web site help line at (919) 541-5384.
    Regulated entities. Entities potentially affected by this action 
include plants engaged in the production of chlorine and caustic in 
mercury cells. Regulated categories and entities include those sources 
listed in the primary Standard Industrial Classification code 2812 or 
North American Information Classification System code 325181.
    This description is not intended to be exhaustive, but rather 
provides a guide for readers regarding entities likely to be regulated 
by this action. To determine whether your facility, company, business, 
organization, etc., is regulated by this action, you should carefully 
examine Sec. 63.8182 of the proposed rule. If you have questions 
regarding the applicability of this action to a particular entity, 
consult the person listed in the preceding FOR FURTHER INFORMATION 
CONTACT section.
    Outline. The information presented in this preamble is organized as 
follows:

I. Background
    A. What is the source of authority for development of NESHAP?
    B. What criteria are used in the development of NESHAP?
    C. What is a mercury cell chlor-alkali plant?
    D. What are the health effects associated with mercury?

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    E. How does this action relate to the part 61 Mercury NESHAP?
II. Summary of Proposed Standards
    A. What is the source category?
    B. What are the affected sources and emission points to be 
regulated?
    C. What are the emission limitations?
    D. What are the work practice standards?
    E. What are the operation and maintenance requirements?
    F. How are initial and continuous compliance with the emission 
limitations to be demonstrated?
    G. How are initial and continuous compliance with the work 
practice standards to be demonstrated?
    H. What are the notification and reporting requirements?
    I. What are the recordkeeping requirements?
III. Rationale for Selecting the Proposed Standards
    A. How did we select the source category?
    B. How did we select the affected sources and emission points to 
be regulated?
    C. How did we select the form of the standards?
    D. How did we determine the basis and level of the proposed 
standards for existing sources?
    E. How did we determine the basis and level of the proposed 
standards for new sources?
    F. How did we select the testing and initial compliance 
requirements?
    G. How did we select the continuous compliance requirements?
    H. How did we select the notification, recordkeeping, and 
reporting requirements?
IV. Summary of Environmental, Energy, Cost, and Economic Impacts
    A. What are the air emission impacts?
    B. What are the non-air health, environmental, and energy 
impacts?
    C. What are the cost and economic impacts?
V. Solicitation of Comments and Public Participation
VI. Administrative Requirements
    A. Executive Order 12866, Regulatory Planning and Review
    B. Executive Order 13132, Federalism
    C. Executive Order 13175, Consultation and Coordination with 
Indian Tribal Governments
    D. Executive Order 13045, Protection of Children from 
Environmental Health Risks and Safety Risks
    E. Unfunded Mandates Reform Act of 1995
    F. Regulatory Flexibility Act (RFA), as amended by the Small 
Business Regulatory Enforcement Fairness Act of 1996 (SBREFA)
    G. Paperwork Reduction Act
    H. National Technology Transfer and Advancement Act
    I. Executive Order 13211, Actions Concerning Regulations that 
Significantly Affect Energy Supply, Distribution, or Use

I. Background

A. What Is the Source of Authority for Development of NESHAP?

    Section 112 of the CAA contains our authorities for reducing 
emissions of hazardous air pollutants (HAP). Section 112(d) requires us 
to promulgate regulations establishing emission standards for each 
category or subcategory of major sources and area sources of HAP listed 
pursuant to section 112(c). Section 112(d)(2) specifies that emission 
standards promulgated under the section shall require the maximum 
degree of reductions in emissions of the HAP subject to section 112 
that are deemed achievable considering cost and any non-air quality 
health and environmental impacts and energy requirements.
    Each national emission standard for hazardous air pollutants 
(NESHAP) established reflects the maximum degree of reduction in 
emissions of HAP that is achievable. This level of control is commonly 
referred to as maximum achievable control technology (MACT).
    Section 112(c)(6) requires us to list source categories and 
subcategories assuring that sources accounting for not less than 90 
percent of the aggregate emissions of each of seven specific pollutants 
(including mercury) are subject to standards under section 112(d) of 
the CAA.
    Mercury cell chlor-alkali plants are among the sources listed to 
achieve the 90 percent goal for mercury.

B. What Criteria Are Used in the Development of NESHAP?

    Section 112(d)(2) specifies that NESHAP for new and existing 
sources must reflect the maximum degree of reduction in HAP emissions 
that is achievable, taking into consideration the cost of achieving the 
emissions reductions, any non-air quality health and environmental 
benefits, and energy requirements. This level of control is commonly 
referred to as MACT.
    Section 112(d)(3) defines the minimum level of control or floor 
allowed for NESHAP. In essence, the MACT floor ensures that the 
standard is set at a level that assures that all affected sources 
achieve the level of control at least as stringent as that already 
achieved by the better-controlled and lower-emitting sources in each 
source category or subcategory. For new sources, the MACT floor cannot 
be less stringent than the emission control that is achieved in 
practice by the best-controlled similar source. The MACT standards for 
existing sources cannot be less stringent than the average emission 
limitation achieved by the best-performing 12 percent of existing 
sources in the category or subcategory (or the best-performing five 
sources for categories or subcategories with fewer than 30 sources).
    In developing MACT, we also consider control options that are more 
stringent than the floor. We may establish standards more stringent 
than the floor based on the consideration of cost of achieving the 
emissions reductions, any non-air quality health and environmental 
impacts, and energy impacts.

C. What Is a Mercury Cell Chlor-alkali Plant?

1. Mercury Cell Chlor-Alkali Production Facilities
    At a mercury cell chlor-alkali plant, mercury cell chlor-alkali 
production facilities are used to manufacture chlorine and caustic as 
co-products and hydrogen as a by-product through the electrolytic 
decomposition of brine in mercury cells. The central unit is the 
mercury cell which is a device comprised of an electrolyzer 
(electrolytic cell) and decomposer with one or more end boxes and other 
components linking them. While each mercury cell is an independent 
production unit, numerous cells are connected electrically in series to 
form a cell circuit. Cells are situated in a cell room and typically 
arranged in two rows separated by a center aisle. The cell room is 
generally a two-story structure in which mercury cells are housed on 
the upper floor. The lower floor houses various process and 
housekeeping functions. The number of mercury cells at a given plant 
ranges from 24 to 116 and averages 56. A mercury cell involves two 
distinct reactions which occur in separate vessels. The electrolyzer 
produces chlorine gas, and the decomposer produces hydrogen gas and 
caustic solution (sodium hydroxide or potassium hydroxide). The 
electrolyzer can be described as an elongated, shallow steel trough 
enclosed by side panels and a top cover. A typical electrolyzer 
measures about 15 meters (about 50 feet) in length and 1.5 meters 
(about 5 feet) in width and holds about 3,600 kilograms (around 8,000 
pounds) of mercury. The decomposer is a 4-to-5 feet high cylindrical 
vessel located at the outlet end of the electrolyzer and is usually 
oriented vertically. The electrolyzer and the decomposer are typically 
linked by an inlet end box and an outlet end box.
    A shallow stream of liquid mercury flows continuously between the

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electrolyzer and the decomposer. The mercury enters the cell at the 
inlet end box and flows down a slight grade to the outlet end box, 
where it flows out of the cell into the decomposer. After being 
processed in the decomposer, the mercury is pumped back to the inlet 
end box of the cell.
    Saturated brine (sodium chloride solution or potassium chloride 
solution) is fed to the electrolytic cell via the inlet end box and 
flows toward the outlet end box above the shallow layer of mercury. 
Both brine and mercury flow beneath dimensionally stable metal anodes, 
typically made of a titanium substrate with a metal catalyst that are 
suspended in the electrolyzer top. The flowing mercury serves as the 
cathode.
    Electric current applied between the anodes and the mercury cathode 
causes a reaction that produces chlorine at the anode, while an alkali 
metal (sodium or potassium) binds with the mercury as an amalgam at the 
cathode. The chlorine gas is collected at the top of the cell and 
transported to an ancillary gas purification system followed in most 
cases by a liquefaction facility. The alkali metal/mercury amalgam 
exits via the outlet end box and enters the decomposer. The brine, 
whose salt content has been partially depleted in the reaction, also 
exits the cell via the outlet end box and is transferred to an 
ancillary brine preparation system.
    The decomposer functions as a packed bed reactor in which the 
alkali metal/mercury amalgam contacts deionized water in the presence 
of a catalyst. The amalgam reacts with the water, liberating the 
mercury and yielding caustic soda (sodium hydroxide) or caustic potash 
(potassium hydroxide) and hydrogen. The caustic and mercury are 
separated in a trap at the end of the decomposer. The caustic and 
hydrogen are each transferred to ancillary treatment, and the mercury 
is pumped back to the inlet end of the cell.
    As previously noted, end boxes serve as connections between the 
electrolyzer and decomposer in a mercury cell. The inlet end box 
collects and combines raw materials at the inlet end of the cell, and 
the outlet end box separates and directs various materials out of the 
cell. An end-box ventilation system, which is present at most but not 
all plants, evacuates the vapor spaces of the end boxes. The end-box 
ventilation system also commonly evacuates the vapor space of other 
vessels and process equipment, such as pump seals, wash water tanks, 
and caustic tanks and headers. In most cases, mercury contained in this 
equipment is covered with a layer of water or other aqueous liquid so 
the air being pulled into the end-box ventilation system is not in 
direct contact with mercury. However, due to the elevated temperatures 
in this equipment, particularly end boxes, mercury diffuses through the 
liquid and is present in the vapor spaces. The concentration of mercury 
in end-box ventilation systems before any steps are taken to remove 
mercury varies greatly depending on the vacated equipment. The 
collected gases are usually cooled and then treated in a mist 
eliminator and other control equipment prior to being discharged to the 
atmosphere. It is the mercury remaining in the treated stream that 
causes the end-box ventilation system vent to be a point source of 
mercury air emissions for plants that have these systems.
    Important ancillary operations at a mercury cell chlor-alkali plant 
include chlorine purification and liquefaction, brine preparation, 
caustic purification, by-product hydrogen cleaning, and wastewater 
treatment.
    Chlorine gas is collected under vacuum from each mercury cell and 
fed into a header system leading out of the cell room. The chlorine 
then undergoes cooling, mist elimination, and drying. Only trace 
amounts of mercury remain in the product chlorine gas, typically less 
than 0.03 parts per million (ppm). Thus, limited mercury emissions are 
associated with the chlorine purification operation, as this level is 
achieved without any steps for mercury removal and is consistent with 
final mercury concentrations for well-controlled gaseous by-product 
hydrogen streams. In most instances, further cooling, compression, and 
liquefaction are conducted to obtain liquid chlorine.
    Brine flows in a continuous loop through the mercury cells and the 
brine preparation system which provides clean saturated brine for 
electrolysis. An important function of the brine system is the removal 
of impurities naturally associated with salt such as calcium, iron, and 
aluminum. The presence of these elements can adversely affect cell 
efficiency. These impurities are removed by the addition of caustic and 
sodium carbonate which react to form metal precipitates that are 
removed by filtration. Subsequently, the brine is acidified to remove 
excess caustic, subjected to heat exchange for temperature adjustment, 
and returned to the mercury cells as clean saturated brine. Mercury 
exists in the brine system in the form of dissolved mercuric chloride 
and on the order of 3 to 25 ppm. The low vapor pressure of mercuric 
chloride, which is approximately 30 times lower than that of elemental 
mercury at 35 deg.C, limits the potential for emissions of mercury from 
the brine system.
    Because the caustic solution produced directly from the decomposer 
is commercial grade, the only additional treatment needed is mercury 
removal. The concentration of mercury in the caustic stream leaving the 
decomposer ranges from about 3 to 15 ppm. Mercury is removed by cooling 
and filtration. Residual mercury contained in the caustic product is 
typically around 0.06 ppm.
    Hydrogen gas exiting a decomposer contains mercury vapor. A 
mercury-saturated hydrogen gas stream typically leaves a decomposer at 
a temperature over 200 deg.F. The mercury concentration of this stream 
can be as high as 3,500 milligrams per cubic meter (mg/m3). 
Accordingly, in most situations, each decomposer is equipped with an 
adjacent cooler through which the hydrogen gas stream is routed to 
condense mercury and return it to the mercury cell. After initial 
cooling, the hydrogen gas from each decomposer is collected into a 
common header. The combined gas is then treated for mercury with 
additional cooling and adsorption (or absorption) control equipment. 
The cleaned hydrogen gas is then either burned as fuel in a boiler, 
transferred to another process as a raw material, or vented directly to 
the atmosphere. Due to the mercury remaining in the treated stream, the 
by-product hydrogen stream is a point source of mercury air emissions.
    Mercury cell chlor-alkali plants generate a variety of aqueous 
waste streams that contain mercury and are treated in a wastewater 
treatment system. These wastewaters originate from a variety of 
sources, ranging from wastewaters produced from cell room washdowns and 
cleanup activities to liquids or slurries produced from purged brine 
from the brine system and backwash water from the filtration equipment 
used for caustic purification.
    Wastewater treatment applied at most mercury cell chlor-alkali 
plants entails three basic steps. First, sodium hydrosulfide is added 
to the wastewater (which contains both elemental mercury and mercury 
compounded as mercuric chloride) to form mercuric sulfide. This 
compound has a very low vapor pressure which practically eliminates the 
potential for mercury air emissions from wastewater treatment. Next, 
the mercuric sulfide is removed through precipitation and filtration 
which results in a liquid fraction and a mercuric sulfide filter cake. 
Any dissolved mercury contained in the liquid is removed by treatment 
in a carbon adsorber prior to being

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discharged in accordance with a plant's discharge permit. The 
wastewater treatment sludges produced, which consist mainly of the 
mercuric sulfide filter cake, are classified as hazardous under 
Resource Conservation and Recovery Act (RCRA) regulations (40 CFR part 
261, subpart D). This waste, designated as K106, must be treated for 
mercury removal prior to disposal or landfilling which generally means 
high temperature treatment.
2. Mercury Recovery Facilities
    Nine mercury cell chlor-alkali plants have mercury recovery 
facilities on-site to recover elemental mercury from mercury-containing 
wastes. The wastes treated include those considered K106 wastes, as 
cited above, and debris and nondebris D009 wastes. The D009 wastes, as 
classified under RCRA regulations (40 CFR part 261, subpart D), are 
nonspecific mercury-containing wastes. Debris wastes include any 
contaminated material or item greater than 2\1/2\ inches in any one 
dimension, such as hardware, protective gear, piping, and equipment. 
Nondebris wastes include graphite from decomposers, cell room sump 
sludges, spent carbon media from carbon adsorption control devices, and 
other small solids.
    The most commonly used process is thermal recovery (retorting), 
where mercury-containing wastes are heated to volatilize the mercury 
which is then condensed and recovered. Six plants each operate a 
mercury thermal recovery unit. In such a unit, mercury in wastes is 
driven to the vapor phase at temperatures over 1,000 deg.F inside one 
or more retorts. The retort off-gas, which is rich in mercury vapor, is 
routed through cooling equipment to condense the mercury for recovery. 
However, because it is not possible to condense all of the mercury, the 
off-gas is typically routed through polishing control equipment to 
further reduce mercury before the stream is discharged to the 
atmosphere. This causes the mercury thermal recovery unit vent to be a 
point source of mercury air emissions. Mercury that never vaporizes and 
subsequently is neither condensed nor emitted remains in the retort 
ash, whose mercury content is limited by RCRA land disposal 
restrictions (40 CFR part 268, subpart E).
    Mercury thermal recovery units can be classified, based on the type 
of retort used, as oven type units and non-oven type units. Three 
plants have batch oven retorts, and three plants have non-oven retorts 
(rotary kiln or single hearth). There are differences between the two 
types related to operating temperature and residence time. Oven retorts 
have lower operating temperatures (around 1,000 deg.F) and 
substantially longer residence times (24 to 54 hours) than do kilns 
which operate at around 1,375 deg.F with residence times approaching 3 
hours.
    Noteworthy among all six thermal recovery units is the relatively 
small volume of exhaust gas generated. Volumetric flow rates range from 
around 50 standard cubic feet per minute (scfm) on one oven type unit 
to 1,200 scfm on one non-oven type unit. Non-oven type units have 
higher volumetric flow rates with an average flow rate of 1,000 scfm 
and a median of 1,075 scfm than oven type units with an average of 130 
scfm and a median of 100 scfm.
    Two of the nine plants use a chemical process in which mercuric 
sulfide and elemental mercury in wastes are chemically transformed to 
mercuric chloride from which elemental mercury is then precipitated. 
This process differs from mercury thermal recovery in that it is an 
entirely liquid-phase operation. Moreover, owing to the low vapor 
pressure of mercuric chloride, the potential for mercury air emissions 
from this process is limited. Mercury that is not converted and 
recovered remains in the processed waste materials whose mercury 
content is limited by RCRA land disposal restrictions for nonthermal 
mercury recovery processes (40 CFR part 268, subpart E).
    The ninth plant uses a batch purification still for recovering 
elemental mercury only from end-box residues which are high in mercury 
content. The system involves heating small batches of end-box residues 
to volatilize the mercury contained followed by a condenser for mercury 
recovery. This contrasts with thermal recovery units that treat large 
volumes of low mercury content wastes. The still is operated under 
vacuum such that the gas stream after the condenser is routed through 
two carbon adsorption beds in series to limit mercury air emissions. 
The system is used only a few times per year for 1 to 2 days at a time. 
Due to the small volumetric flow rate and mercury concentration of the 
vented stream and limited operation of the still, mercury air emissions 
are very low from recovery in the batch purification still.
    Fugitive mercury emissions can occur due to leaking equipment, 
liquid mercury spills, or accumulations in many locations throughout 
mercury cell chlor-alkali production facilities and mercury recovery 
facilities, including areas of maintenance activities, liquid mercury 
collection and handling, and storage for mercury-containing wastes. 
Most of these sources are associated with cell rooms. Liquid mercury 
exposed to the atmosphere evaporates at a rate depending on 
temperature, air flow, and other variables. Methods of controlling 
fugitive mercury emissions include the containment of liquid mercury 
leaks, clean up of liquid mercury spills and accumulations, repair of 
equipment leaking liquid mercury, and containment of mercury-containing 
wastes under an aqueous liquid or in closed containers. Since liquid 
mercury can be visually identified, routine visual inspections are an 
effective method to detect these problems. Mercury vapor leaks, by 
comparison, are much more difficult to detect and typically result in 
higher emissions. Vapor leaks occur mostly at the decomposer and in the 
hydrogen system.

D. What are the Health Effects Associated With Mercury?

    Mercury is highly toxic, persistent, and bioaccumulates in the food 
chain. Most people have some exposure to mercury as a result of normal 
daily activities. People may be exposed to mercury through inhalation 
of ambient air; consumption of contaminated food, water, or soil; and/
or dermal exposure to substances containing mercury. Also, exposures 
occur as the result of dental amalgams and from various other sources.
    Mercury is a naturally occurring element that is found in air, 
water, and soil in various inorganic and organic forms. The three 
primary forms of interest are elemental mercury, inorganic mercury, and 
methylmercury. As mercury moves through environmental media, it 
undergoes complex transformations.
    Mercury emitted to the air from various types of sources (usually 
in elemental or inorganic forms) transports through the atmosphere and 
eventually deposits onto land or water bodies. Once deposited, natural 
processes can transform some of the mercury into methylmercury which is 
a highly toxic, more bioavailable form that biomagnifies in the aquatic 
food chain (such as in fish). Generally, fish consumption dominates the 
pathway for human and wildlife exposure to mercury.
    Inhalation is the primary direct exposure route of concern for 
elemental mercury because this form strongly partitions to air. 
Absorption of elemental mercury vapor occurs rapidly through the lungs. 
Once absorbed, elemental mercury is readily distributed throughout the 
body; it crosses both placental and blood-brain barriers. The

[[Page 44676]]

elemental mercury is oxidized to divalent mercury in most body tissues. 
Once elemental mercury crosses these barriers and is oxidized to 
divalent mercury, return to the general circulation is impeded, and 
mercury can be retained in brain tissue. Effects on the nervous system 
appear to be the most sensitive toxicological endpoint following 
exposure to elemental mercury. Exposures above the threshold level can 
result in tremors, nervousness, insomnia, neuromuscular changes (such 
as weakness, muscle atrophy, and muscle twitching), headaches, 
polyneuropathy, and memory loss.
    Inhalation and ingestion exposure routes are of interest for 
inorganic mercury because this form is found in air and other media 
such as soils and water. There is some limited information suggesting 
that about 40 percent of the inhaled inorganic mercury is absorbed. 
Absorption of inorganic mercury through the gastrointestinal tract 
varies with the particular mercuric salt involved. The portion that is 
absorbed remains in the body for a considerable length of time. The 
reported half-life of inorganic mercury in blood is about 20 to 66 
days. There is no evidence that inorganic mercury is methylated to form 
methylmercury in the human body. The inorganic mercury has a limited 
capacity for penetrating the blood-brain or placental barriers. Limited 
data suggest that inorganic mercury is a possible human carcinogen. The 
most sensitive general systemic adverse effect due to exposure to 
inorganic mercury is the formation of autoimmune glomerulonephritis 
(that is, inflammation of the kidney).
    Ingestion is the primary exposure route of interest for 
methylmercury. Dietary methylmercury is almost completely absorbed into 
the blood and distributed to all tissues, including the brain. It also 
readily passes through the placenta to the fetus and fetal brain. 
Methylmercury has a relatively long half-life in the human body (about 
70 to 80 days). Neurotoxicity is the health effect of greatest concern 
with methylmercury exposure. The developing fetus is considered most 
sensitive to the effects from methylmercury. Therefore, women of child-
bearing age are the population of greatest concern. During several 
poisoning incidents in Minamata, Japan, in the 1950's and Iraq in the 
1970's, children born of women who were exposed to high doses of 
methylmercury during pregnancy through ingestion of contaminated fish 
or grain suffered neurological harms. These harms included death, 
cerebral palsy, or delayed onset of walking and talking. Also, lower in 
utero exposures have resulted in delays and deficits in learning 
abilities.

E. How Does This Action Relate to the Part 61 Mercury NESHAP?

    We promulgated the National Emission Standard for Mercury on April 
6, 1973 (40 CFR part 61, subpart E).\1\ Those standards (hereafter 
referred to as the Mercury NESHAP) limit mercury emissions from mercury 
cell chlor-alkali plants as well as mercury ore processing facilities 
and sludge incineration and drying plants. Specifically, the Mercury 
NESHAP limits mercury emissions from mercury cell chlor-alkali plants 
to 2,300 grams per day and requires that mercury emissions be measured 
(in a one-time test) from hydrogen streams, end-box ventilation 
systems, and the cell room ventilation system. As an alternative to 
measuring ventilation emissions from the cell room to demonstrate 
compliance, the Mercury NESHAP allows an owner or operator to assume a 
ventilation emission value of 1,300 grams per day of mercury providing 
the owner/operator adheres to a suite of approved design, maintenance 
and housekeeping practices. Every mercury cell chlor-alkali plant 
currently in operation in the United States complies with the cell room 
ventilation provisions by carrying out these practices rather than by 
measuring mercury emissions discharged from the cell room. Since every 
plant uses the 1,300 grams per day assumed value for its cell room 
ventilation emissions, subtracting the 1,300 grams per day cell room 
value from the 2,300 grams per day plantwide standard effectively 
creates an emission limit for the combined emissions from hydrogen 
streams and end-box ventilation systems of 1,000 grams per day.
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    \1\ This regulatory program was originally set forth at 38 FR 
8826, April 6, 1973; and amended at 40 FR 48302, October 14, 1975; 
47 FR 24704, June 8, 1982; 49 FR 35770, September 12, 1984; 50 FR 
46294, November 7, 1985; 52 FR 8726, March 19, 1987; and 53 FR 
36972, September 23, 1988.
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    The requirements in today's proposed standards are more stringent 
than the requirements in the Mercury NESHAP. Using the 1,000 grams per 
day value as the baseline, we estimate that the mercury emissions would 
be reduced to less than 60 grams per day (on average) by the proposed 
rule. This represents about 94 percent reduction from the Mercury 
NESHAP baseline for vents. In addition, the work practice standards in 
today's proposal represent the most explicit compilation of practices 
currently employed by the industry, along with detailed recordkeeping 
and reporting requirements and requirements that supplement existing 
RCRA provisions for the storage of mercury-containing wastes. While we 
cannot quantify the mercury emissions reductions that would be achieved 
by the proposed work practice standards, we are confident that their 
implementation would result in additional reductions in mercury 
emissions beyond that currently achieved by the existing Mercury 
NESHAP.
    We believe that every aspect of the Mercury NESHAP that applies to 
mercury cell chlor-alkali plants is addressed in today's proposed 40 
CFR part 63, subpart IIIII. In fact, as discussed above, the proposed 
requirements are more stringent than the respective requirements in the 
Mercury NESHAP. Consequently, we believe that when mercury cell chlor-
alkali plants are required to comply with the proposed rule as the 
promulgated, the requirements of the Mercury NESHAP that apply to them 
will no longer be relevant or applicable. Therefore, upon the proposed 
compliance date as indicated in Sec. 63.8186 of the proposed rule, 
mercury cell chlor-alkali plants will no longer have any obligation to 
comply with the Mercury NESHAP, nor will they be allowed to comply with 
the Mercury NESHAP instead of the applicable provisions in the proposed 
40 CFR part 63, subpart IIIII. Specifically, we are proposing that 
affected sources subject to the proposed rule would no longer be 
subject to Secs. 61.52(a), 61.53(b) and (c), and 61.55(b), (c) and (d) 
of 40 CFR part 61, subpart E, after the compliance date which is 
proposed to be 2 years following the promulgation of the final rule.

II. Summary of the Proposed Standards

A. What Is the Source Category?

    The source category is Chlorine Production. However, this proposal 
only applies to one type of chlorine production process--the mercury 
cell chlor-alkali process. Today's proposal applies to all plants 
engaged in the manufacture of chlorine and caustic in mercury cells. 
Other chlor-alkali cell types used to produce chlorine and caustic, 
such as diaphragm cell and membrane cell technologies, would not be 
covered by this proposed rule because they do not emit mercury. 
Emissions of chlorine and HCL from all chlorine production facilities 
are addressed in a separate action elsewhere in today's Federal 
Register.

[[Page 44677]]

B. What Are the Affected Sources and Emission Points To Be Regulated?

    The proposed rule defines two affected sources: mercury cell chlor-
alkali production facilities and mercury recovery facilities. The 
former includes all cell rooms and ancillary operations used in the 
manufacture of chlorine, caustic, and by-product hydrogen at a plant 
site. The latter includes all processes and associated operations 
needed for mercury recovery from wastes.
    Emission points addressed within mercury cell chlor-alkali 
production facilities include each mercury cell by-product hydrogen 
stream, each mercury cell end-box ventilation system vent, and fugitive 
emission sources throughout each cell room and various areas. Emission 
points addressed within mercury recovery facilities include each 
mercury thermal recovery unit vent and fugitive emission sources 
associated with storage areas for mercury-containing wastes.

C. What Are the Emission Limitations?

    For new or reconstructed mercury cell chlor-alkali production 
facilities, the proposed rule would prohibit mercury emissions.
    For existing mercury cell chlor-alkali production facilities with 
end-box ventilation systems, we are proposing that aggregate mercury 
emissions from all by-product hydrogen streams and end-box ventilation 
system vents not exceed 0.067 grams of total mercury emitted per 
megagram of chlorine produced (grams Hg/Mg Cl2), or 1.3 x 
10-4 pounds of total mercury per ton of chlorine produced 
(lb Hg/ton Cl2). For existing mercury cell chlor-alkali 
production facilities without end-box ventilation systems, we are 
proposing that mercury emissions from all by-product hydrogen streams 
not exceed 0.033 grams Hg/Mg Cl2, or 0.66 x 10-4 
lb Hg/ton Cl2. In addition, we are proposing that separate 
mercury concentration operating limits be established for each affected 
by-product hydrogen stream and each affected end-box ventilation system 
vent. The mercury concentration operating limits would be based only on 
elemental mercury, and each vent stream outlet would be continuously 
monitored for elemental mercury to show relative changes in mercury 
levels.
    For new, reconstructed, or existing mercury recovery facilities 
with oven type mercury thermal recovery units, we are proposing that 
total mercury emissions not exceed 23 milligrams per dry standard cubic 
meter (mg/dscm) from each oven type unit vent. For new, reconstructed, 
or existing mercury recovery facilities with non-oven type mercury 
thermal recovery units, the proposed limit is 4 mg/dscm. Additionally, 
we are proposing that a mercury concentration operating limit (based on 
elemental mercury) be established concurrent with the initial 
performance test for each mercury thermal recovery unit vent.

D. What Are the Work Practice Standards?

    We are proposing a set of work practice standards to address and 
mitigate fugitive mercury releases at mercury cell chlor-alkali plants. 
These provisions include specific equipment standards such as the 
requirement that end boxes either be closed (that is, equipped with 
fixed covers), or that end-box headspaces be routed to a ventilation 
system. Other examples include requirements that piping in liquid 
mercury service have smooth interiors, that cell room floors be free of 
cracks and spalling and coated with a material that resists mercury 
absorption, and that containers used to store liquid mercury have 
tight-fitting lids. The proposed work practice standards also include 
operational requirements. Examples of these include requirements to 
allow electrolyzers and decomposers to cool before opening, to keep 
liquid mercury in end boxes and mercury pumps covered by an aqueous 
liquid at a temperature below its boiling point at all times, to 
maintain end-box access port stoppers in good sealing condition, and to 
rinse all parts removed from the decomposer for maintenance prior to 
transport to another work area.
    A cornerstone of the proposed work practice standards is the 
inspection program for equipment problems, leaking equipment, liquid 
mercury accumulations and spills, and cracks or spalling in floors and 
pillars and beams. Specifically, the proposed rule would require that 
visual inspections for equipment problems, such as end-box access port 
stoppers not securely in place, liquid mercury in open containers not 
covered by an aqueous liquid, or leaking vent hoses, be conducted twice 
each day (once every 12 hours). If a problem is found during an 
inspection, the owner or operator would need to take immediate action 
to correct the problem. Monthly inspections for cracking or spalling in 
cell room floors would also be required as well as semiannual 
inspections for cracks and spalling on pillars and beams. Any cracks or 
spalling found would need to be corrected within 1 month.
    Visual inspections for liquid mercury spills or accumulations would 
be required twice per day. If a liquid mercury spill or accumulation is 
identified during an inspection, the owner or operator would need to 
initiate cleanup of the liquid mercury within 1 hour of its detection. 
Acceptable cleanup methods would include wet vacuum cleaning, washing 
to a trench or canal with an aqueous liquid cover, or a suitable 
alternative method approved upon petition.
    In addition to cleanup, the proposed rule would require that an 
inspection of equipment in the area of the spill or accumulation be 
conducted to identify the source of the liquid mercury. If the source 
is found, the owner or operator would be required to repair the leaking 
equipment as discussed below. If the source is not found, the owner or 
operator would be required to reinspect the area every 6 hours until 
the source is identified or until no additional liquid mercury is found 
at that location.
    Inspections of specific equipment for liquid mercury leaks would be 
required once per day. If leaking equipment is identified, the proposed 
rule would require that any dripping mercury be contained and covered 
by an aqueous liquid, and that a first attempt to repair leaking 
equipment be made within 1 hour of the time it is identified. The 
proposed rule would require that leaking equipment be repaired within 4 
hours of the time it is identified, although there are provisions for 
delaying repair of leaking equipment for up to 48 hours.
    Inspections for hydrogen gas leaks would be required twice per day 
(once each 12 hours). For a hydrogen leak at any location upstream of a 
hydrogen header, a first attempt at repair would be required within 1 
hour of detection of the leaking equipment, and the leaking equipment 
would need to be repaired within 4 hours (with provisions for delay of 
repair if the leaking equipment is isolated). For a hydrogen leak 
downstream of the hydrogen header but upstream of final control, a 
first attempt at repair would be required within 4 hours, and complete 
repair would be required within 24 hours (with delay provisions if the 
header is isolated).
    As a complement to the inspection program, the proposed rule also 
includes a requirement to institute a cell room monitoring program 
whereby owners and operators would continuously monitor mercury 
concentration in the upper portion of each cell room and take 
corrective actions as soon as practicable when elevated mercury vapor 
levels are

[[Page 44678]]

detected. The proposed rule does not include detailed requirements for 
this program. However, we do plan to develop specific criteria for such 
a program which would be issued either as guidance outside of the final 
rule or as an amendment to the final rule.
    The program would not be a continuous monitoring system inasmuch as 
the results would be used only to determine relative changes in mercury 
vapor levels rather than compliance with a cell room emission or 
operating limit. Generally, the owner or operator would need to 
establish an action level for each cell room which would be based on 
preliminary monitoring to determine normal baseline conditions. The 
action level, or levels if appropriate, would then be established as a 
yet to be determined multiple of the baseline values. Once the action 
level(s) is established, continuous monitoring would need to be 
conducted. If an action level is exceeded, actions to correct the 
situation would need to be initiated as soon as possible. If the 
elevated mercury vapor level is due to a maintenance activity, the 
owner or operator would need to ensure that all work practices related 
to that maintenance activity are followed. If a maintenance activity is 
not the cause, inspections and other actions would be needed to 
identify and correct the cause of the elevated mercury vapor level.
    For fugitive mercury emissions associated with storage areas for 
mercury-containing waste, the proposed rule would require that carbon 
media from decomposers and cell room sludges either be stored in closed 
containers or be stored in open containers under a layer of aqueous 
liquid that is replenished at least once per week. For all other 
mercury-containing wastes, the proposed rule would require that the 
wastes either be washed or chemically decontaminated to remove visible 
mercury or be stored in closed containers.
    Finally, the proposed rule would establish the duty for owners and 
operators to routinely wash surfaces throughout the plant where liquid 
mercury could accumulate. Owners and operators would be required to 
prepare and follow a written washdown plan detailing how and how often 
specific areas specified in the proposed rule would be washed down to 
remove any accumulations of liquid mercury.

E. What Are the Operation and Maintenance Requirements?

    We are proposing that each owner and operator would always operate 
and maintain affected source(s), including air pollution control and 
monitoring equipment, in a manner consistent with good air pollution 
control practices at least to the levels required by the proposed rule, 
as required under Sec. 63.6(e)(1)(i) of the NESHAP General Provisions. 
The proposed rule would require each owner and operator to prepare and 
implement a written startup, shutdown, and malfunction plan according 
to the operation and maintenance requirements in Sec. 63.6(e)(3) of the 
NESHAP General Provisions.

F. How Are Initial and Continuous Compliance With the Emission 
Limitations To Be Demonstrated?

    The proposed rule would require compliance with emission 
limitations within 2 years from [DATE OF PUBLICATION OF THE FINAL RULE 
IN THE Federal Register].
    To demonstrate initial compliance with the proposed emission limits 
for by-product hydrogen streams and end-box ventilation system vents, 
we are proposing that each owner and operator would conduct performance 
tests and perform specified calculations. A test would be needed for 
each by-product hydrogen stream using 40 CFR part 61, appendix A, 
Method 102. A test would also be required for each end-box ventilation 
system vent using 40 CFR part 61, appendix A, Method 101 or 101A. Each 
performance test would be conducted in accordance with a site-specific 
test plan prepared pursuant to the performance test quality assurance 
program requirements in Sec. 63.7(c)(2) of the NESHAP General 
Provisions. Each performance test would be comprised of at least three 
runs, each lasting 2 hours at a minimum. Concurrent with each test run, 
the quantity of chlorine produced would need to be determined according 
to an equation contained in the proposed rule that calculates chlorine 
production based on cell line electric current load. Then, the mass of 
mercury emitted per unit mass of chlorine produced would be calculated 
for each test run, and the runs would be averaged for each tested vent. 
Initial compliance would be achieved if the sum of the average mass of 
mercury emitted per mass of chlorine produced of all by-product 
hydrogen streams and all end-box ventilation system vents is less than 
0.067 gm Hg/Mg Cl2 for plants with end-box ventilation 
systems, or if the sum of the average mass of mercury emitted per mass 
of chlorine produced of all by-product hydrogen streams is less than 
0.033 gm Hg/Mg Cl2 for plants without end-box ventilation 
systems.
    To demonstrate initial compliance with the mercury thermal recovery 
unit emission limits, we are proposing that a performance test be 
conducted for each vent using Method 101 or 101A. Once again, the 
performance test would need to follow a site-specific test plan 
developed by the owner and operator according to Sec. 63.7(c)(2) of the 
NESHAP General Provisions. The proposed rule would require that during 
the test, the type of waste resulting in the highest mercury 
concentration in the mercury thermal recovery unit vent be processed. 
Documentation of the mercury content of this type of waste and an 
explanation of why it results in the highest mercury concentration 
would be required as part of the site-specific test plan. Three test 
runs would need to be conducted at a point after the last control 
device for each vent. Initial compliance would be achieved if the 
average vent mercury concentration is less than 23 mg/dscm for each 
oven type vent or 4 mg/dscm for each non-oven type vent.
    To continuously comply with the emission limit for each by-product 
hydrogen stream, end-box ventilation system vent, and mercury thermal 
recovery unit, we are proposing that each owner and operator would 
continuously monitor outlet elemental mercury concentration and compare 
the daily average results with a mercury concentration operating limit 
for the vent. This operating limit would be established during the 
required performance tests, as explained later in this section. 
Continuous compliance would be demonstrated by collecting outlet 
elemental mercury concentration data using a continuous mercury vapor 
monitor, calculating daily averages, and documenting that the 
calculated daily average values are no higher than established 
operating limits. Each daily average vent elemental mercury 
concentration greater than the established operating limit would be 
considered a deviation.
    The proposed rule would require that each continuous mercury vapor 
monitor be installed, operated, and maintained in accordance with a 
site-specific monitoring plan. For each monitor, this plan would need 
to address installation and siting, monitor performance specifications, 
performance evaluation procedures and calibration criteria, ongoing 
operation and maintenance procedures, ongoing data assurance 
procedures, and ongoing recordkeeping and reporting procedures.
    Owners or operators would establish a mercury concentration 
operating limit for each by-product hydrogen stream, end-box 
ventilation system vent, and mercury thermal recovery unit vent as part 
of the initial compliance demonstration. During each

[[Page 44679]]

performance test, the proposed rule would require that a continuous 
mercury vapor monitor be used to measure elemental mercury 
concentration in the vent stream at least once every 15 minutes for the 
entire duration of each performance test run. The average elemental 
mercury concentration measured during any valid test run conducted 
during the performance test in which mercury emissions did not exceed 
the applicable emission limit would then be established as the mercury 
concentration operating limit.

G. How Are Initial and Continuous Compliance With the Work Practice 
Standards To Be Demonstrated?

    The proposed rule would require compliance with the work practice 
standards within 2 years from [DATE OF PUBLICATION OF THE FINAL RULE IN 
THE Federal Register]. The proposed work practice standards would 
primarily be requirements for ongoing operational activities. For these 
activities, there is no specific action called for to demonstrate 
initial compliance, other than a commitment by the owner or operator 
that the work practices standards will be met. Therefore, the major 
component of the initial compliance demonstration for the work practice 
standards would be a certification by the owner or operator that the 
work practice standards will be met. In addition, there are a few 
requirements that could cause an owner or operator to install new 
equipment or upgrade existing equipment. Documentation of any such 
actions would also be required in the initial compliance demonstration.
    The proposed rule contains specific recordkeeping requirements 
related to the work practice standards. These include records of when 
inspections were conducted, problems identified, and actions taken to 
correct problems. Continuous compliance with work practice standards 
would be demonstrated by maintaining these required records.
    Initial compliance with the washdown plan would be demonstrated by 
submission of the plan by the owner or operator and certification that 
they operate according to, or will operate according to, the plan. 
Continuous compliance with the plan would be demonstrated by 
maintaining related records. Records would also be required to 
demonstrate compliance with the cell room monitoring program.

H. What Are the Notification and Reporting Requirements?

    The proposed rule would require that owners or operators submit the 
following notifications and reports:
     Initial Notification
     Notification of Intent to conduct a performance test
     Notification of Compliance Status (NOCS)
     Compliance reports.
    For the Initial Notification, we are proposing that each owner or 
operator notify us that their plant is subject to the NESHAP for 
mercury cell chlor-alkali plants, and that they provide other basic 
information about the plant. For existing sources, this notification 
would need to be submitted no later than [DATE 120 CALENDAR DAYS AFTER 
PUBLICATION OF THE FINAL RULE IN THE Federal Register].
    For the Notification of Intent report, we are proposing that each 
owner or operator notify us in writing of the intent to conduct a 
performance test at least 60 days before the performance test is 
scheduled to begin.
    The Notification of Compliance Status for the work practice 
standards would be due [DATE 30 DAYS AFTER THE PUBLICATION OF THE FINAL 
RULE IN THE Federal Register] for existing sources. In this 
notification, the owner or operator would need to certify that the work 
practice standards are being or will be met. Furthermore, we are 
proposing that the washdown plan be submitted as part of this 
notification, and that the owner or operator certify that they operate 
or will operate according to the plan.
    For the emission limits where a performance test is required to 
demonstrate initial compliance (that is, the emission limits for by-
product hydrogen streams and end-box ventilation system vents and the 
mercury thermal recovery unit vent limits), the tests would have to be 
conducted within 180 days after the compliance date, and the 
Notification of Compliance Status would be due 60 days after the 
completion of the performance test. We are proposing that the site-
specific plan addressing the use of continuous mercury vapor monitors 
for vents be submitted as part of this notification.
    Reporting on continuous compliance would be required semiannually, 
with the first report due within the first 6 months after initial 
compliance.

I. What Are the Recordkeeping Requirements?

    Records required by the proposed rule related to by-product 
hydrogen streams, end-box ventilation system vents, and mercury thermal 
recovery unit vents include the following: performance test results, 
records showing the establishment of the applicable mercury 
concentration operating limits (including records of the mercury 
concentration monitoring conducted during the performance tests), 
records of the continuous mercury concentration monitoring data, 
records of the daily average elemental mercury concentration values, 
and records associated with site-specific monitoring plans.
    With regard to the work practice standards, the proposed rule would 
require that records be maintained to document when each required 
inspection was conducted and the results of each inspection. Records 
noting equipment problems (such as end-box cover stoppers not securely 
in place or mercury in an open container not covered by an aqueous 
liquid) identified during a required inspection and the corrective 
action taken would also be required. If equipment that is leaking 
mercury liquid or hydrogen/mercury vapor is identified during a 
required inspection or at any other time, the proposed rule would 
require records of when the leak was identified and when it was 
repaired. Similarly, if a mercury spill or accumulation is identified 
at any time, the proposed rule would require records of when the spill 
or accumulation was found and when it was cleaned up.
    A copy of the current version of the washdown plan would need to be 
kept on-site and be available for inspection. Records of when washdowns 
were conducted would be required.
    The proposed rule would require that copies of each notification 
and report that is submitted to comply with this subpart be kept and 
maintained for 5 years, the first 2 of which must be on-site.

III. Rationale for Selecting the Proposed Standards

A. How Did We Select the Source Category?

    The mercury cell chlor-alkali production portion of the chlorine 
production source category was among the categories and subcategories 
of major and area sources listed for regulation under section 112(c)(6) 
of the CAA (63 FR 17838, April 10, 1998) to assure that sources 
accounting for not less than 90 percent of the aggregate mercury 
emissions nationwide are subject to standards under section 112(d). We 
estimate that mercury cell chlor-alkali production accounts for

[[Page 44680]]

over 5 percent of all stationary source emissions of mercury and over 
25 percent of the emissions from stationary noncombustion sources. The 
Chlorine Production source category is comprised of 43 facilities 
engaged in the manufacture of chlorine and caustic in electrolytic 
cells. Cell types employed include the diaphragm cell, membrane cell, 
and mercury cell. Of these, only the mercury cell process has the 
potential to emit mercury. For the 1997 base year of the MACT analysis, 
twelve facilities employed mercury cells. We are aware that one of the 
twelve facilities ceased operations permanently in September 2000. 
Nonetheless, we considered it to be part of the source category for the 
development of MACT since it was in operation in 1997.

B. How Did We Select the Affected Sources and Emission Points To Be 
Regulated?

    For the purposes of implementing NESHAP, an affected source is 
defined to mean the stationary source, the group of stationary sources, 
or the portion of a stationary source that is regulated by relevant 
standards or other requirements established under section 112 of the 
CAA. An affected source specifies the group of unit operations, 
equipment, and emission points that are subject to the standards. We 
can define an affected source as narrowly as a single piece of 
equipment or as broadly as all equipment at a plant site.
    We decided to separate the unit operations and emission points 
related to the production of chlorine and caustic from the unit 
operations and emissions points related to mercury recovery. Mercury 
cell chlor-alkali production facilities include a number of integrated 
operations dedicated to the production, storage, and transfer of 
product chlorine, product caustic, and by-product hydrogen. In 
contrast, mercury recovery facilities are operations dedicated to the 
recovery of mercury from mercury-containing wastes. These operations 
are independent of the chlor-alkali process and are thus not integral 
to production. As a result, the proposed rule addresses emissions from 
two separate affected sources: mercury cell chlor-alkali production 
facilities and mercury recovery facilities.
    Unit operations and emission points grouped within the mercury cell 
chlor-alkali production facilities affected source are by-product 
hydrogen streams, end-box ventilation system vents, and fugitive 
mercury emissions associated with cell rooms, hydrogen systems, caustic 
systems, and storage areas for mercury-containing wastes. As described 
previously, each is a potentially significant source of mercury 
emissions. Chlorine purification, brine preparation, and wastewater 
treatment operations are believed to have low mercury emissions to the 
air. Accordingly, today's proposal contains no requirements for these 
operations.
    Unit operations and emission points grouped within the mercury 
recovery facilities affected source include all mercury thermal 
recovery unit vents and fugitive mercury emissions associated with 
mercury-containing waste storage areas. Chemical mercury recovery and 
recovery in a batch purification still are believed to have low mercury 
emissions to the air. Accordingly, today's proposal contains no 
requirements for these operations.

C. How Did We Select the Form of the Standards?

    Section 112 of the CAA requires that standards be specified as 
numerical emission standards, whenever possible. However, if it is 
determined that it is not feasible to prescribe or enforce a numerical 
emission standard, section 112(h) indicates that a design, equipment, 
work practice, or operational standard may be specified.
    With the exception of standards for fugitive emission sources, we 
are proposing numerical emission limits for all other mercury emission 
sources. Specifically, the proposed standards include numerical 
emission limits for by-product hydrogen streams, end-box ventilation 
system vents, and mercury thermal recovery unit vents.
    Cell rooms bring together mercury, a large electrical load, and hot 
production equipment. Accordingly, most fugitive mercury emission 
sources at mercury cell chlor-alkali plants are associated with cell 
rooms. Reliable quantification of these cell room fugitive emissions 
would be costly, owing to the need to measure both mercury vapor 
concentration and air flow rate at ceiling apertures with sophisticated 
equipment. Some plants have many separate ceiling apertures, and plants 
in warm climates tend to be little enclosed on the sides. Moreover, 
levels of fugitive mercury vary with cell room operations, precluding 
the setting of a numerical limit.
    Mercury cell chlor-alkali plant fugitive mercury emission sources 
are also associated with storage areas for mercury-containing wastes. 
The measurement of mercury emissions from mercury-containing waste 
storage areas is also impracticable as these are usually located in 
several places throughout a plant, many of which are open areas.
    Not unexpectedly, emissions data on cell room and waste storage 
emissions are very limited as in the case of cell rooms, or nonexistent 
as in the case of waste storage areas. As such, we believe that it is 
not feasible to either prescribe or enforce numerical emission limit(s) 
for fugitive mercury emissions from cell rooms and waste storage areas. 
Consequently, today's proposed standards address fugitive emission 
sources at mercury cell chlor-alkali plants through the establishment 
of work practice standards.

D. How Did We Determine the Basis and Level of the Proposed Standards 
for Existing Sources?

    Section 112 of the CAA establishes a minimum baseline or ``floor'' 
for MACT standards. For new sources, the standards for a source 
category or subcategory cannot be less stringent than the emission 
control that is achieved in practice by the best-controlled similar 
source. The standards for existing sources may be less stringent than 
standards for new sources, but they cannot be less stringent than the 
average emission limitation achieved by the best-performing 12 percent 
of existing sources for categories and subcategories with 30 or more 
sources, or the average emission limitation achieved by the best-
performing five sources for categories or subcategories with fewer than 
30 sources for which the Administrator has emissions information.
    After the floor has been determined for a category or subcategory, 
the Administrator must set MACT standards that are technically 
achievable and no less stringent than the floor. Such standards must 
then be met by all sources within the category or subcategory. The 
regulatory alternatives selected for new and existing sources may be 
different because of different MACT floors, and separate emission 
limits may be established for new and existing sources.
    The EPA generally determines the MACT floor and then considers 
beyond-the-floor control options. Here, EPA considers the achievable 
reductions in emissions of HAP (and possibly other pollutants that are 
co-controlled), cost and economic impacts, energy impacts, and other 
non-air environmental impacts. The objective is to achieve the maximum 
degree of HAP emission reduction without incurring unreasonable cost or 
other impacts.

[[Page 44681]]

1. By-Product Hydrogen Streams and End-Box Ventilation System Vents
    The fundamental unit in the mercury cell chlor-alkali process is a 
mercury cell. The by-product hydrogen stream and the end-box 
ventilation system vent represent the mercury emission point sources 
that originate from a mercury cell. As discussed earlier, hydrogen gas 
is incidentally produced as a result of the catalyzed reaction of 
sodium/mercury amalgam and deionized water to produce caustic in a 
decomposer. The end-box ventilation stream is a collection of vapors 
from head spaces of end boxes and possibly other vessels, including 
pump tanks and seal legs, wash water tanks, and caustic tanks and 
headers. The mercury content of the by-product hydrogen stream and the 
end-box ventilation stream, prior to control, is a direct function of 
the design of the mercury cell. Ten different mercury cell models are 
used by the twelve mercury cell chlor-alkali plants. Given these 
differences in cell design and their effect on potential vent mercury 
emissions, we opted to develop a cell-wide standard for mercury 
emissions from both points.
    Given the large variation among the plants in terms of production 
capacity (the largest plant is capable of producing over five times as 
much chlorine as the smallest) and mercury emissions potential, we 
concluded that any equitable assessment of MACT should account for this 
disparity. We selected the actual amount of chlorine produced by weight 
as the uniform parameter for our analysis for the following reasons: 
Chlorine is the primary product generated; chlorine production can be 
accurately determined; and chlorine and hydrogen are generated in the 
same stoichiometric quantities, that is one molecule of hydrogen is 
produced for each molecule of chlorine produced.
    We then considered the fact that two plants do not have end-box 
ventilation systems. Both plants operate cells with closed end boxes. 
Consequently, there is no need for end-box ventilation and, therefore, 
no end-box ventilation system emission point. Next, we examined whether 
the mercury cells at the ten plants equipped with end-box ventilation 
systems could be reconfigured with closed end boxes. We concluded that 
the use of an end-box ventilation system is an inherent feature of the 
original design of a cell, and that it is not technically feasible to 
eliminate end-box ventilation systems at these plants. We have, 
therefore, decided to distinguish plants with end-box ventilation 
systems and plants without these systems for purposes of establishing 
MACT.
    Accordingly, we are proposing, for plants with end-box ventilation 
systems, a single emission limit for mercury emissions from all by-
product hydrogen streams and mercury emissions from all end-box 
ventilation system vents in units of mass of mercury emissions per mass 
of chlorine produced. For plants without end-box ventilation systems, 
we are proposing an emission limit for mercury emissions from all by-
product hydrogen streams in units of mass of mercury emissions per mass 
of chlorine produced.
     Emission Limit for Plants With End-Box Ventilation Systems
    In order to establish MACT for the combined mercury emissions from 
by-product hydrogen streams and end-box ventilation system vents, we 
relied on estimates of annual mercury emissions for each vent and 
information on annual chlorine production provided by the ten plants 
with end-box ventilation systems. A total of twenty mercury emission 
estimates were provided, one emission estimate for all by-product 
hydrogen streams and one emission estimate for all end-box ventilation 
system vents at each of the ten plants. Background information on these 
emission estimates is available in the docket to this rulemaking (No. 
A-2000-32).
    Of the twenty emission estimates, fourteen (six for by-product 
hydrogen streams and eight for end-box ventilation system vents) are 
based on stack tests performed in accordance with established EPA 
reference methods specific to chlor-alkali plants. These include Method 
101 for the determination of particulate and gaseous mercury from air 
streams (i.e., end-box ventilation system vents) and Method 102 for the 
determination of mercury in hydrogen streams. We obtained and reviewed 
copies of all available test reports and determined that the tests were 
conducted correctly. Six emission estimates (four for by-product 
hydrogen streams and two for end-box ventilation system vents) are 
based on periodic measurements of mercury concentration in the vent 
streams. The methods used for these periodic measurements are largely 
modifications of EPA reference test methods. As such, we believe that 
they provide reasonably accurate results consistent with what would 
otherwise be obtained with the EPA reference test methods. Our 
conclusion is that these data represent the best information available 
on mercury emissions from these vents, and that they are appropriate 
for use in establishing MACT.
    The MACT floor was calculated as follows. For each plant, we 
divided the sum of the reported annual mercury emissions from all by-
product hydrogen streams and end-box ventilation system vents by the 
annual chlorine production. The chlorine production values used are 
largely representative of actual annual chlorine production levels. We 
then ranked the plants from lowest to highest emitters for combined 
normalized mercury emissions. The normalized mercury emission values 
range from 0.067 grams Hg/Mg Cl2 to 3.41 grams Hg/Mg 
Cl2. We should note that the lowest value, 0.067 grams Hg/Mg 
Cl2, is from the plant that closed permanently in September 
2000. Nonetheless, we believe that it is appropriate to retain it in 
the pool of existing sources used to determine existing source MACT. 
Prior to closure, this plant was the lowest-emitting and best-
performing source. The average (mean) of the best (lowest) five 
normalized values results in a floor value for existing sources of 0.14 
grams Hg/Mg Cl2.
    Of the ten plants with by-product hydrogen streams and end-box 
ventilation systems, we project that seven would need to install 
additional controls or upgrade existing controls to meet the 0.14 grams 
Hg/Mg Cl2 floor level. We assume the following plant-
specific actions: Two plants would need to install new carbon adsorbers 
on their by-product hydrogen streams (one plant would be replacing an 
existing adsorber with a new, larger adsorber); one plant would need to 
install a new packed scrubber on its end-box ventilation system vent; 
three plants would need to install new controls on both their by-
product hydrogen streams and end-box ventilation system vents; and one 
plant would need to both upgrade carbon adsorber control on its by-
product hydrogen stream by switching to impregnated carbon and 
replacing carbon more frequently as well as install a new packed 
scrubber on its end-box ventilation system vent.
    We estimate that the total aggregate installed capital control 
costs needed to meet the existing source MACT floor for the seven 
affected plants to be about $660,000. We estimate total aggregate 
annual control costs, including costs for labor, materials, 
electricity, capital recovery, taxes, insurance, and administrative 
charges (excluding costs for monitoring, reporting, and recordkeeping) 
for the seven affected plants to be about $570,000 per year. Mercury 
emission reductions against actual emissions would total 556 kg/yr 
(1,225 lbs/yr) for the seven affected plants. Mercury emission 
reductions

[[Page 44682]]

against the potential-to-emit baseline, as represented by the allowable 
emissions under the Mercury NESHAP, would total over 3,400 kg/yr (over 
7,500 lbs/yr) for the seven affected plants. The associated annual cost 
per unit of mercury emission reduction values would be approximately 
$465 per pound (actuals baseline) and under $80 per pound (potential-
to-emit baseline), respectively.
    Water pollution impacts due to the increased use of packed bed 
scrubbers involving aqueous hypochlorite scrubbing solution on end-box 
ventilation systems are estimated to total 1.2 million liters (320 
thousand gallons) of additional wastewater. Impacts on solid waste due 
to increased use of carbon adsorption for by-product hydrogen streams 
are estimated to total 17 megagrams per year (Mg/yr), 19 tons per year 
(tpy), of mercury-containing spent carbon. Energy requirements are 
estimated to total an additional 878 thousand kilowatt-hours per year 
(kW-hr/yr). Estimated secondary air pollution impacts due to heightened 
energy consumption total 282 Mg/yr (311 tpy), with carbon dioxide 
emissions comprising 99 percent of the estimate.
    We then examined beyond-the-floor MACT options. We selected the 
lowest normalized value among the ten plants, namely 0.067 grams Hg/Mg 
Cl2, as a beyond-the-floor option. As noted above, this 
0.067 grams Hg/Mg Cl2 value is from a plant that is now 
closed. Nonetheless, as stated previously, we believe it is appropriate 
to retain it in the pool of existing sources and to include it in the 
beyond-the-floor assessment.
    The 0.067 grams Hg/Mg Cl2 value corresponds to 0.05 
grams Hg/Mg Cl2 from the by-product hydrogen stream 
controlled by a condenser coupled with a molecular sieve adsorber, and 
0.017 grams Hg/Mg Cl2 from the end-box ventilation system 
vent, also controlled by a condenser coupled with a molecular sieve 
adsorber. It is our understanding that molecular sieve technology for 
mercury vapor emission control is no longer commercially available. We, 
thus, acknowledge some uncertainty associated with the achievability of 
this level of control. However, for the reasons set forth below, we 
believe that other technologies and operating practices exist that can 
achieve this level of emissions control.
    Due to the very low volumetric flow rates associated with both by-
product hydrogen streams and end-box ventilation system vents 
(typically less than 5,000 scfm and 4,500 scfm, respectively), we 
believe that the retrofit of control equipment to reduce mercury 
emissions is both practical and reasonable. We project that the nine 
plants with baseline emissions greater than 0.067 grams Hg/Mg 
Cl2 would meet the 0.067 grams Hg/Mg Cl2 beyond-
the-floor option through the installation of new controls or the 
upgrading of existing controls. We assume the following plant-specific 
actions: two plants would need to install new carbon adsorbers on their 
by-product hydrogen streams (one plant would be replacing an existing 
adsorber with a new, larger adsorber); three plants would need to 
install a new packed scrubber on their end-box ventilation system 
vents; three plants would need to install new controls on both their 
by-product hydrogen streams and end-box ventilation system vents; and 
one plant would need to both upgrade existing carbon adsorber control 
on its by-product hydrogen stream by switching to impregnated carbon 
and replacing carbon more frequently as well as install a new packed 
scrubber on its end-box ventilation system vent. We project that the 
five new carbon adsorbers would need to accommodate a 25 percent higher 
carbon charge than assumed to meet the floor option. Upgrades to 
existing carbon adsorber control would involve more frequent carbon 
replacement than that assumed to meet the floor option. Five of the 
seven new packed scrubbers on end-box ventilation systems would need to 
be operated more efficiently than assumed to meet the floor option.
    In evaluating regulatory options that are more stringent than the 
floor, we must consider the cost of achieving such emission reductions, 
and any non-air quality health and environmental impacts and energy 
requirements. The beyond-the-floor option would result in an additional 
76 kg/yr (168 lb/yr) of total mercury emission reductions for the nine 
affected plants (a 48 percent incremental reduction from the floor 
option). For the nine affected plants, the incremental installed 
capital costs are estimated to total around $210,000, and the 
incremental annual costs are estimated to total around $150,000 per 
year. The incremental cost per unit of incremental mercury emission 
reduction is $900 per pound.
    The incremental water pollution impacts are estimated to total 550 
thousand liters (145 thousand gallons) of additional wastewater. The 
incremental solid waste impacts are estimated as 5.1 Mg/yr (5.6 tpy) of 
mercury-containing spent carbon in total. The incremental energy 
impacts are estimated as 110 thousand kW-hr/yr in total. The 
incremental secondary air pollution impacts are estimated to total 35 
Mg/yr (39 tpy), with carbon dioxide emissions comprising 99 percent of 
the estimate.
    We believe the additional emission reductions that would be 
achieved by the beyond-the-floor option are warranted. Further, we 
believe that the incremental costs of achieving such emission 
reductions, as well as incremental non-air environmental impacts and 
energy requirements, are reasonable for mercury. Therefore, we selected 
the 0.067 grams Hg/Mg Cl2 beyond-the-floor option as MACT 
for plants with end-box ventilation systems.
    If comments are received on this proposal that lead us to conclude 
that this level of control is unachievable, we retain the option of 
setting the standard at the next lowest normalized emission value. 
Accordingly, we have evaluated the impacts of an alternative 0.076 
grams Hg/Mg Cl2 mercury emission limit for plants with end-
box ventilation systems.
    We project that the eight plants with baseline emissions greater 
than 0.076 grams Hg/Mg Cl2 would need to install new 
controls or upgrade existing controls to meet this level. This would 
result in an additional 65 kg/yr (143 lb/yr) of total mercury emission 
reductions for the eight affected plants (a 41 percent incremental 
reduction) from the floor option. We assume the same plant-specific 
actions as those assumed to meet the 0.067 grams Hg/Mg Cl2 
value, given the small difference in emission reductions at the two 
levels. For the eight affected plants, the incremental installed 
capital costs are estimated to total around $197,000, and the 
incremental annual costs are estimated to total around $125,000 per 
year. The incremental cost per unit of incremental mercury emission 
reduction is $875 per pound.
    The incremental water pollution impacts are estimated to total 317 
thousand liters (84 thousand gallons) of additional wastewater. The 
incremental solid waste impacts are estimated as 5.1 Mg/yr (5.6 tpy) of 
mercury-containing spent carbon in total. The incremental energy 
impacts are estimated as 105 thousand kW-hr/yr in total. The 
incremental secondary air pollution impacts are estimated to total 34 
Mg/yr (37 tpy), with carbon dioxide emissions comprising 99 percent of 
the estimate.
     Emission Limit for Plants Without End-Box Ventilation 
Systems
    In order to establish MACT for mercury emissions from by-product 
hydrogen streams for the two plants without end-box ventilation 
systems, we used estimates of annual mercury

[[Page 44683]]

emissions from by-product hydrogen streams and information on actual 
chlorine production provided by the two plants for 1997. Both emission 
estimates are based on periodic measurements of mercury concentration 
in the vent streams obtained using methods that are largely 
modifications of EPA reference test methods. Background information on 
these emission estimates is available in the docket to this rulemaking 
(No. A-2000-32).
    For each plant, we divided the reported annual mercury emissions 
from by-product hydrogen streams by the annual chlorine production. The 
normalized values are 0.033 grams Hg/Mg Cl2 and 0.17 grams 
Hg/Mg Cl2. Although there are fewer than five sources from 
which to constitute a MACT floor, we opted to take the average (mean) 
of the two normalized values, resulting in 0.10 grams Hg/Mg 
Cl2 as the floor value for existing sources. We project that 
the higher emitting plant would need to upgrade existing controls to 
meet the 0.10 grams Hg/Mg Cl2 floor level. Specifically, the 
carbon in its existing carbon adsorbers would need to be replaced more 
frequently. There would be no capital costs as more frequent carbon 
media replacement is only a recurring annual cost estimated at $13,000 
per year. Mercury emission reductions against actual emissions would 
total 6 kg/yr (14 lbs/yr). Mercury emission reductions against the 
potential-to-emit baseline, as represented by the allowable emissions 
under the Mercury NESHAP, would total over 600 kg/yr (over 1,300 lbs/
yr). The associated annual cost per unit of mercury emission reduction 
values would be approximately $940 per pound and less than $10 per 
pound, respectively. There are no associated secondary air pollution, 
water pollution, or energy impacts. Estimated solid waste impacts due 
to increased use of carbon adsorption total 1.0 Mg/yr (1.1 tpy).
    We then examined beyond-the-floor MACT options. We selected the 
lowest normalized value among the two plants, namely 0.033 grams Hg/Mg 
Cl2, as a beyond-the-floor option. Controls applied to 
achieve this value include a condenser coupled with a carbon adsorber. 
For purposes of estimating impacts, we assumed that the higher-emitting 
plant would replace its existing carbon adsorber with a new, larger 
adsorber to meet the 0.033 grams Hg/Mg Cl2 level.
    In evaluating regulatory options that are more stringent than the 
floor, we must consider the cost of achieving such emission reduction, 
and any non-air quality health and environmental impacts and energy 
requirements. The beyond-the-floor option would result in an additional 
6 kg/yr (14 lb/yr) of total mercury emission reductions (a 47 percent 
incremental reduction from the floor option). The incremental installed 
capital costs are estimated to total around $182,000. The incremental 
annual costs are estimated to total around $126,000 per year. The 
incremental cost per unit of incremental mercury emission reduction is 
approximately $9,000 per pound. There are no associated incremental 
water pollution impacts. The estimated incremental solid waste impacts 
total an additional 5.3 Mg/yr (5.8 tpy) of mercury-containing spent 
carbon. The incremental energy impacts are estimated as 252 thousand 
kW-hr/yr in total. The incremental secondary air pollution impacts are 
estimated to total 81 Mg/yr (89 tpy), with carbon dioxide emissions 
comprising 99 percent of the estimate.
    We believe the additional emission reductions that would be 
achieved by the beyond-the-floor option are warranted. Further, we 
believe that the incremental costs of achieving such emission 
reductions as well as incremental non-air environmental impacts and 
energy requirements are reasonable for mercury. Therefore, we selected 
the 0.033 grams Hg/Mg Cl2 level as MACT for plants without 
end-box ventilation systems, which is approximately half the level 
selected for plants with end-box ventilation systems.
2. Sources of Fugitive Mercury Emissions
    As explained above, we have determined that work practice standards 
provide the most appropriate approach for addressing fugitive mercury 
emissions at mercury cell chlor-alkali plants. Every mercury cell 
chlor-alkali plant is currently subject to the Mercury NESHAP and 
implements the design, maintenance, and housekeeping practices 
referenced in the NESHAP to control fugitive cell room emissions. We 
believe that these existing requirements represent the MACT floor for 
existing mercury fugitive emission sources. Since these floor 
requirements are currently observed at each existing plant, a standard 
based on this floor level of control would not be expected to reduce 
mercury emissions from current levels or produce any associated cost, 
non-air environmental or energy impacts.
    We then examined beyond-the-floor options. We noted that many of 
the existing work practice requirements are general in nature and 
nonspecific relative to the frequency and scope of inspections, as well 
as recordkeeping and reporting. We decided that clarification and 
elaboration on these general practices was warranted to make them more 
explicit and to improve assurance of compliance. Accordingly, we 
initiated a thorough examination of specific measures employed across 
the industry to limit fugitive mercury emissions.
    In the summer of 1998, we conducted site visits to five mercury 
cell chlor-alkali plants to observe and document their design, 
operational, maintenance, housekeeping, and recordkeeping practices. 
The five plants were selected to provide a broad representation of 
ownership (the five plants are owned by five different companies) and 
different mercury cell models (mercury cells made by all three 
manufacturers and of varying sizes are represented). We also selected 
plants in different areas of the United States (U.S.) to account for 
geographical variations such as climate. In addition to the site 
visits, we obtained current standard operating procedures for 
mitigating sources of fugitive mercury emissions from all twelve 
plants. We used this knowledge and information to develop a detailed 
compilation of practices currently used across the industry to control 
fugitive mercury emissions.
    We used this compilation to identify explicit practices for each 
individual plant area, equipment type, and inspection procedure and 
assembled them as beyond-the-floor work practice requirements. We feel 
that the resulting work practice standards represent the most stringent 
practices applied in the industry.
    The types of enhancements from the MACT floor level requirements 
that are included in the beyond-the-floor option may be generally 
classified in three categories. First, the beyond-the-floor 
requirements add considerable specificity. The equipment and areas to 
be inspected are identified along with the required frequency of the 
inspections and the conditions that trigger corrective action. Response 
time intervals for when the corrective actions must occur are also 
included. Second, some types of inspections are required at more 
frequent intervals than required by the Mercury NESHAP (e.g., 
inspecting decomposers for hydrogen leaks once each 12 hours rather 
than once each day). Third, the beyond-the-floor option includes 
additional requirements not included in the floor level. The two most 
obvious examples are the detailed recordkeeping procedures and 
reporting provisions which are more fully developed than

[[Page 44684]]

those in the Mercury NESHAP and the requirements for storage of 
mercury-containing wastes.
    Also included in the beyond-the-floor option is a requirement for 
owners and operators to develop and implement a plan for the routine 
washdown of accessible surfaces in the cell room and other areas. All 
plants currently wash down cell room surfaces regularly. However, due 
to plant-specific considerations, we are uncomfortable with issuing a 
specific set of requirements for washdowns that would apply at all 
plants. As a result, the beyond-the-floor option establishes the duty 
for owners or operators to prepare and implement a written plan for 
washdowns and identifies elements to be addressed in the plan. Although 
washdowns are an ongoing practice at all plants, we believe that 
including such a requirement in the beyond-the-floor option will 
elevate the importance of washdowns as part of an overall approach to 
reducing cell room fugitive emissions.
    As a final element of the beyond-the-floor option, we considered 
the extent to which measurement of ambient mercury levels in the cell 
room air should be incorporated. Currently, all mercury cell chlor-
alkali plants periodically monitor mercury vapor levels at the cell 
room floor plane, in keeping with Occupational Safety and Health 
Administration (OSHA) standards for worker exposure to mercury. 
Typically, on a daily basis, a plant operator measures and records the 
mercury vapor level in the cell room. Some plants use technologies that 
measure the mercury vapor level at a single point, such as portable 
mercury vapor analyzers based on ultraviolet light absorption or gold 
film amalgamation detection. Plant operators using these technologies 
take readings at specified locations in the cell room. Other plants 
utilize procedures that provide an aggregate reading, such as chemical 
absorption into potassium permanganate solution followed by separate 
cold vapor atomic absorption analysis in a laboratory setting. This 
composite sample is most often obtained by a plant operator walking 
through the cell room with a small sampling pump.
    When a mercury vapor level above the OSHA personal exposure limit 
is measured, plant operators require the use of respirators in the 
area. They also take action to determine and eliminate the cause of the 
elevated mercury level.
    Given the fact that all plants conduct cell room mercury vapor 
measurements, we determined that it was appropriate to include 
requirements to conduct cell room monitoring as a means to identify and 
correct situations resulting in elevated mercury levels (and obviously, 
increased mercury emissions) as part of the beyond-the-floor option for 
fugitive mercury emission sources. We considered basing such a program 
on periodic measurement, which would correspond to the programs 
currently in place at mercury cell chlor-alkali plants. We also 
considered basing such a program on the continuous measurement of 
mercury vapor levels in the upper portions of the cell room. We are 
aware of technologies, including extractive, cold vapor spectroscopy 
systems and open-path, differential optical absorption spectroscopy 
systems, designed for such continuous monitoring applications. In 
August of 2000, we studied cell room mercury vapor levels at a U.S. 
mercury cell chlor-alkali plant using both extractive and open-path 
technologies. In addition, we are aware of extractive systems currently 
in use in Europe for this purpose.
    Upon consideration of the benefits of periodic versus continuous 
monitoring of the cell room mercury vapor levels, we selected 
continuous monitoring as part of the proposed cell room monitoring 
program for the following reasons. First, we believe that continuous 
monitoring would identify hydrogen leaks or other situations that 
result in elevated mercury levels in the cell room much more promptly 
than periodic monitoring. If periodic monitoring was conducted on a 
daily basis, hours could pass before such a leak was detected. We also 
believe that the continuous monitoring of mercury vapor levels during 
maintenance activities would provide information to help plant 
operators refine and improve such maintenance activities to reduce 
mercury emissions.
    Finally, we believe that the monitoring on the cell room floor 
plane could fail to detect hydrogen leaks or other situations resulting 
in mercury vapor leaks that may occur at higher elevations. Continuous 
monitoring in the upper portion of the cell room would provide a 
representation of all areas of the cell room at all levels.
    Therefore, we have included a program involving the continuous 
monitoring of mercury vapor levels in the cell room as part of the 
beyond-the-floor option. We envision the basic elements for this 
program to be as follows. Each owner or operator would be required to 
install a mercury monitoring system in each cell room and continuously 
monitor the elemental mercury concentration in the upper portion of the 
cell room. The type of technology, whether an extractive, cold vapor 
spectroscopy system or an open-path, differential optical absorption 
spectroscopy system, would be at the discretion of the owner or 
operator, provided that performance criteria, such as a minimum 
detection limit, were met. A sampling configuration would be specified 
to acquire a composite measurement representative of the entire cell 
room air. For example, the sampling configuration may involve sampling 
at least three points along the center aisle of the cell room and above 
the mercury cells at a height sufficient to ensure representative 
readings.
    For each cell room, the owner or operator would need to establish 
an action level which would be based on preliminary monitoring to 
determine normal baseline conditions. The onset and duration of this 
preliminary monitoring would be specified as well as guidelines for 
setting the action level. Continuous monitoring would commence after a 
specified time period following establishment of the action level and 
its documentation in a notification to us. A minimum data acquisition 
requirement would be established, such as a requirement to collect and 
record data for at least a certain percent of the time in any 6-month 
period.
    Actions to correct the situation as soon as possible would be 
required when measurements above the action level were obtained over a 
defined duration, such as a certain number of consecutive measurements 
or an average over a certain time period above the action level. If the 
elevated mercury vapor level was due to a maintenance activity, the 
owner or operator would need to keep records describing the activity 
and verifying that all work practices related to that maintenance 
activity are followed. If a maintenance activity was not the cause, 
then inspections and other actions would need to be conducted within 
specific time periods to identify and correct the cause of the elevated 
mercury vapor level.
    In evaluating whether to establish the beyond-the-floor option as 
MACT, we looked at the incremental impacts on emissions, cost, energy, 
and other non-air effects. Relative to emissions, we firmly believe 
that although we are unable to actually quantify the reductions 
expected with the implementation of the beyond-the-floor option, 
substantial reductions would nonetheless occur. We know from experience 
and inference that the added scrutiny inherent in the suite of beyond-
the-floor practices will of necessity result in fewer fugitive 
emissions. In considering the cost impacts of the

[[Page 44685]]

beyond-the-floor option, we attempted to estimate the cost associated 
with the equipment needed to carry out cell room monitoring as well as 
increased demand for labor and overhead needed to fully implement the 
proposed monitoring, inspection, recordkeeping, and reporting 
activities. We estimate the total installed capital costs needed to 
meet the beyond-the-floor option for fugitive mercury emissions to be 
around $663,000. We estimate the total annual costs to be around 
$840,000 per year, consisting of about $94,000 for annualized capital 
expenditure on mercury monitoring systems; about $736,000 per year for 
labor for monitoring, inspections, and recordkeeping, about $2,100 per 
year for mercury monitoring system utilities, and about $7,500 per year 
for mercury monitoring system replacement parts. We are unable to 
estimate increases in wastewater associated with washdown and cleanup 
activities for liquid mercury spills and accumulations as well as 
increases in solid waste since these would be highly plant-specific. 
Energy requirements for mercury monitoring systems are estimated to 
total an additional 53 thousand kW-hr/yr. Estimated secondary air 
pollution impacts due to heightened energy consumption total 17 Mg/yr 
(19 tpy), with carbon dioxide emissions comprising 99 percent of the 
estimate.
    We believe the additional emission reductions that would be 
achieved by the beyond-the-floor option are warranted and that the 
estimated incremental costs to meet this level are reasonable. 
Therefore, we are selecting the beyond-the-floor work practice 
standards as MACT for fugitive mercury emission sources.
    With regard to the cell room monitoring program, we acknowledge 
that there are uncertainties associated with the use of mercury 
monitoring systems for continuous monitoring that can only be addressed 
through actual field validation. We are specifically requesting comment 
on the feasibility of using such systems for continuous monitoring to 
prompt corrective actions for elevated mercury vapor levels in the cell 
room. We are also requesting comment on the detailed elements of the 
cell room monitoring program which we are unable to delineate in its 
entirety at this time.
    Following proposal, we will involve the public in defining this 
program. Specifically, we will enter into a joint effort with industry, 
monitoring instrument suppliers, and other interested parties, to 
detail the elements and requirements of this program. We will take 
additional appropriate rulemaking steps as necessary to fully implement 
this program, including assuring opportunity for industry and the 
public to comment.
3. Mercury Thermal Recovery Unit Vents
    As previously discussed, nine of the twelve mercury cell chlor-
alkali plants have mercury recovery processes. Six of the nine plants 
operate a thermal recovery unit in which mercury-containing wastes are 
heated and the resulting mercury-laden off-gas is cooled and treated 
for mercury removal prior to being discharged to the atmosphere. Two 
plants recover mercury with a chemical process and one plant recovers 
mercury in a purification still; in both cases, mercury air emissions 
are believed to be low.
    In establishing MACT for mercury thermal recovery units, we 
obtained information from all six plants with these units. Each plant 
provided descriptions of its thermal recovery operation, including the 
types of wastes processed and the control devices applied. Where 
available, plants also provided results of performance testing or 
periodic sampling and an estimate of their mercury emissions.
    Each of the six plants operates one or more retorts (as part of its 
mercury thermal recovery unit) in which mercury-containing wastes are 
heated to a temperature sufficient to volatilize the mercury. The off-
gas containing mercury vapor is then cooled in the mercury recovery/
control system, causing the mercury to condense to liquid. The liquid 
mercury condensate is then collected from recovery devices for reuse in 
the mercury cells. The primary emission source is the mercury thermal 
recovery unit vent where off-gas that has passed through the recovery/
control system is discharged to the atmosphere. Retorts used include 
three basic designs: batch oven (three plants), rotary kiln (two 
plants), and single hearth (one plant).
    The batch ovens are D-tube retorts which are so named because each 
resembles an uppercase letter ``D'' on its side. Pans are filled with 
waste, typically around 10 cubic feet, and then placed into an oven. 
After inserting three or four pans, the oven door is closed and the 
retort is indirectly heated to about 1,000 deg.F. The residence time 
varies from about 24 to 48 hours, depending on the type of waste being 
processed. While heating, the oven is kept under a vacuum and the 
mercury vapors are pulled into the mercury recovery/control system. 
After the cycle is completed, the unit is allowed to cool and the pans 
are then removed.
    The rotary kilns are long, refractory-lined rotating steel 
cylinders in which the waste charge to be treated flows counter current 
to hot combustion gases used for heating. Wastes to be treated are 
conveyed into a ram feeder which inserts a waste charge into the kiln 
at regular intervals, typically about every 5 minutes. Each is directly 
fired with natural gas and is heated to over 1,300 deg.F. The rotation 
of the kiln provides for mixing and transfer of the waste to the 
discharge end. The residence time is about 3 hours. The gas stream 
leaving the kiln passes through an afterburner where the temperature is 
increased to around 2,000 deg.F to complete combustion reactions 
involving sulfur and carbon and then to a mercury recovery/control 
system.
    The single hearth retort is comprised of a vertically mounted, 
refractory lined vessel with a single hearth and a rotating rabble. 
Waste is charged onto the hearth through a charge door by way of a 
conveyor. Once charged, the conveyor is withdrawn, the charge door is 
closed, and the heating or treatment cycle begins. The waste is stirred 
by the rabble rake, which turns continuously, and is heated to around 
1,350 deg.F. The residence time, which ranges according to waste type, 
is typically much longer than for rotary kilns. Similar to rotary 
kilns, the gas stream leaving the hearth retort passes through an 
afterburner where the temperature is increased to around 2,000 deg.F to 
complete combustion reactions involving sulfur and carbon and then to a 
mercury recovery/control system.
    As noted above, there are several important differences between the 
oven retorts and the non-oven (rotary kiln and single hearth) retorts 
related to operating temperature and residence time. There are also 
significant differences in the volumetric flow rates produced by the 
oven and the non-oven retorts. Oven retorts typically have volumetric 
flow rates around 100 scfm, which is an order of magnitude lower than 
flow rates for non-oven retorts which are around 1,000 scfm. Together, 
these differences can have a material impact on mercury concentration, 
mass flow rate of mercury, and other factors that influence mercury 
loadings to the recovery/control system. After evaluation of these 
technical and operational differences between oven retorts and non-oven 
retorts and their potential effect on emissions characteristics and 
control device applicability, we are proposing to distinguish between 
retort types for the purpose of establishing MACT.
    With the exception of the plant with a single hearth retort that is 
controlled

[[Page 44686]]

with a scrubber as the final control device, the recovery/control 
system at each plant consists of condensation and carbon adsorption for 
final mercury control. The amount and type of carbon adsorbent used in 
the fixed bed, nonregenerative carbon adsorbers varies among the five 
plants. One plant uses activated carbon, one uses iodine-impregnated 
carbon, and three use sulfur-impregnated carbon. We believe that each 
type is effective in removing mercury provided the adsorbent is 
replaced at a frequency appropriate to prevent breakthrough.
    In contrast, the plant with the single hearth retort utilizes a 
chlorinated brine packed-tower scrubber for final mercury control. In 
this scrubber, elemental mercury vapor is removed by chemically 
reacting with the chlorinated brine solution to form mercuric chloride, 
a nonvolatile mercury salt which is readily soluble in aqueous 
solutions. The resulting scrubber effluent is returned to the brine 
system causing the absorbed mercury to be recycled back to the mercury 
cells. Performance data for this brine scrubber system shows that the 
effectiveness is comparable to that of the condenser/carbon adsorber 
systems used at the other five plants.
    While examining the performance capabilities of the condenser/
carbon adsorber systems, we identified several factors that influence 
performance. We believe that a primary factor affecting mercury 
recovery and control is the temperature to which retort off-gas is 
cooled prior to entering the final control device. Because of the 
volatile nature of elemental mercury, temperature has a direct effect 
on the concentration of mercury vapor that can exist in a gas stream. 
For example, the concentration of mercury vapor that could exist in a 
gas stream at 50 deg.F is 5 mg/m3, while the predicted 
concentration at 85 deg.F is 30 mg/m3, a six-fold increase. 
At 100 deg.F, the concentration could potentially be over 50 mg/
m3.
    A key factor relative to the performance of carbon adsorbers is 
contact time. As noted previously, we believe that generally each of 
the carbon adsorbents presently used in the industry can effectively 
collect mercury vapor. However, it is essential for optimum performance 
that the contact time between the gas stream to be treated and the 
carbon adsorbent be long enough to allow for maximum adsorption. 
Consequently, design and operational factors such as carbon bed depth, 
sorbent particle size, and gas velocity have an appreciable impact on 
collection efficiency. Another key consideration is the frequency at 
which the adsorbent is replaced since the adsorbing capacity of any 
sorbent decreases as saturation and breakthrough are approached.
    In assessing potential formats for a numerical emission limit, we 
considered a limit on emissions in a specified time period, a limit 
normalized on the amount of wastes processed, and an outlet mercury 
concentration limit. The amounts and types of wastes processed at each 
plant and among plants vary considerably. We believe, generally, that 
mercury emissions from the thermal recovery unit vent are proportional 
to the amount of mercury-containing wastes processed and the amount of 
mercury contained in these wastes. Therefore, we concluded that 
limiting emissions over a specified time period would unfairly impact 
plants that process larger amounts of wastes and/or wastes that contain 
more mercury. A mercury emission limit normalized on the amount of 
wastes processed would eliminate this inequity. However, given the wide 
variation in the mercury content of different types of wastes and the 
varying mix of waste types processed at different plants, we concluded 
that setting and enforcing such an emissions limit is impractical.
    Several factors influence the concentration of mercury in the 
thermal recovery unit vent exhaust. The most significant include the 
mercury content of the wastes being processed and the volumetric flow 
rate through the system. Volumetric flow rate is dependent on process 
rate, fuel usage, and the volume of combustion gas generated. The 
mercury concentration may also vary depending on the stage of the 
heating cycle. The mercury content of the exhaust stream leaving the 
condenser(s) or other type of cooling unit should remain relatively 
constant, provided that the outlet temperature is constant and the 
residence time is sufficient. Depending on the effectiveness of the 
carbon adsorber or brine scrubber, the mercury concentration would be 
further reduced. As a result, we conclude that concentration at the 
outlet of the final control device is the most meaningful and practical 
measure of the combined performance of each element of the mercury 
recovery/control system. Therefore, we have selected concentration for 
the format of the MACT standard for mercury thermal recovery units.
    Finally, we evaluated how, or if, the proposed standards should 
address different waste types; that is, should different emission 
limits be set for different waste types or should one limit be set for 
the waste type shown to be the highest emitting. We analyzed all the 
available data but were unable to ascertain any relationship between 
the type of waste (K106, D009 debris, or D009 nondebris) being treated 
during testing or sampling and the outlet mercury concentration 
measured across all plants. As a result, we are proposing an outlet 
mercury concentration limit that is neutral to the type of waste being 
processed. The analysis also influenced our decision on the proposed 
requirements for performance testing. We are proposing that testing be 
conducted during conditions representative of the most extreme, 
relative to potential mercury concentration, expected to occur under 
normal operation. While we would have preferred that the proposed rule 
specify the type of waste to be processed during testing, our inability 
to discern a relationship between waste type and outlet mercury 
concentration across plants prevented us from doing so. Therefore, the 
proposed rule would obligate owners and operators to process mercury-
containing wastes that result in the highest vent mercury concentration 
during performance testing.
    In summary, our review and analysis of all the available 
information on mercury thermal recovery units leads us to the following 
conclusions:
     Separate MACT emission limits should be developed for oven 
type and non-oven (rotary kiln and single hearth) type mercury thermal 
recovery units.
     These emission limits should not distinguish among waste 
types processed.
     Concentration is the appropriate format for the numerical 
emission limits.
    The following describes how we selected the proposed emission 
limits for oven type and non-oven type mercury thermal recovery units.
    There are three plants that use oven retorts. All are owned and 
operated by the same company. One plant operates five ovens, another 
operates three ovens, and the third operates two ovens. Thermal 
recovery at all three plants is conducted between 6,000 to 7,000 hours 
per year. The amounts of waste processed and the amounts of mercury 
recovered range from 90 to almost 300 tpy and from 3 to 20 tpy, 
respectively. At all three plants, the mercury-laden off-gas leaving 
the retort is cooled and treated for particulates and acid gases in a 
wet scrubber with caustic solution, followed by further cooling in a 
condenser. The cooled gas is then routed through one or more fixed-bed, 
nonregenerative carbon adsorbers before being discharged to the 
atmosphere. We conducted an evaluation of the mercury

[[Page 44687]]

recovery/control systems at all three plants, considering the condenser 
outlet temperature and the amount of carbon in the beds.
    The plant that ranked highest in this evaluation, which we consider 
to be the best-controlled plant, provided mercury emissions data 
(periodic sampling results) over 3 years. The other two plants were 
unable to provide emissions data. Therefore, data from this best-
controlled plant were used to establish MACT. Since an emission limit 
based on the best-controlled plant would obviously be more stringent 
than the floor level, the selection of a level associated with the 
best-performing recovery/control system for this retort type clearly 
meets our statutory requirement regarding the minimum level allowed for 
NESHAP.
    This best-controlled plant has five ovens and two separate but 
identical mercury recovery/control systems. One treats the exhaust gas 
from three ovens while the other services two ovens. Each system is 
comprised of a wet scrubber and condenser, which cool the exhaust gases 
to around 70 deg.F, followed by a carbon adsorber with about 700 pounds 
of activated carbon. Available test data for this plant consist of 
bimonthly measurements for 1997, 1998, and 1999 on each stack. We 
reviewed the sampling method used to obtain these data which are 
largely based on EPA reference methods for mercury emissions from 
mercury cell chlor-alkali plants and concluded that it is capable of 
producing measurements of reasonable accuracy that are suitable for use 
as the basis for MACT. We removed six data points that we determined 
were statistical outliers and combined the data for both control 
systems into one data set comprised of 134 individual measurements.
    We then evaluated options for how these data should be used to 
establish a numerical emission limit to represent MACT. While this 
limit must represent the performance of the controls in place at this 
best-controlled plant, it also must account for variability in outlet 
mercury concentration due to processing different mercury-containing 
waste types and normal variation in recovery/control equipment 
performance. As noted previously, we are proposing that performance 
tests for mercury thermal recovery units be conducted under the most 
challenging conditions, which we are defining as the processing of 
wastes that result in the highest recurring mercury concentration in 
the vent exhaust. Each performance test would consist of at least three 
runs, and the average concentration measured would be compared with the 
emission limit to determine compliance. Given our inability to 
establish a discernible correlation between waste type processed and 
emissions, our obligation to set standards that are achievable under 
the full range of normal acceptable operating conditions and the fact 
that initial performance is based on at least three separate test runs, 
we chose to set the standard based on the average of the three highest 
measured values in the data set of 134 measurements for the best-
controlled plant. The three measured values are 20.4, 22.1, and 26.4 
mg/m3. The average of the three is 23 mg/dscm, which we are 
proposing as the mercury concentration emission limit for oven type 
units.
    Due to the very low volumetric flow rates associated with oven type 
mercury thermal recovery unit exhaust streams (typically less than 300 
scfm), we believe that the retrofit of control equipment to reduce 
mercury emissions is both practical and reasonable. For purposes of 
estimating the impacts of the proposed emission limit, we assumed that 
the two plants with lower-performing control systems would need to 
install new, larger carbon adsorbers to meet the 23 mg/dscm level. The 
total installed capital control costs are estimated to be around 
$217,000 for all three plants, and the total annual control costs are 
estimated to be around $163,000 per year for all three plants. 
Estimated mercury emission reductions against actual baseline emissions 
would total 33 kg/yr (74 lbs/yr) for all three plants. The associated 
annual cost per unit of mercury emission reduction would be 
approximately $2,200 per pound.
    Impacts on solid waste due to increased use of carbon adsorption 
are estimated total 5.2 Mg/yr (5.7 tpy) of mercury-containing spent 
carbon. Energy requirements are estimated to be an additional 473 
thousand kW-hr/yr. Estimated secondary air pollution impacts due to 
heightened energy consumption are 152 Mg/yr (168 tpy), with carbon 
dioxide emissions comprising 99 percent of the estimate.
    As noted previously, three plants operate retorts other than oven-
type retorts. Thermal recovery at these three plants is conducted 
between 1,500 and 5,000 hours per year. The amounts of waste processed 
and the amounts of mercury recovered range from 50 to 500 tpy and from 
3 to 12 tpy, respectively. The mercury recovery/control systems 
operated at the two plants with rotary kiln retorts consist of direct 
contact cooling, particulate and acid gas scrubbing, condensation, and 
carbon adsorption. The retort off-gas at both plants is cooled to a 
temperature of 55 deg. F on average before being routed through two 
fixed-bed, nonregenerative adsorbers containing sulfur-impregnated 
carbon media. The mercury recovery/control system at the plant with a 
single hearth retort employs a direct contact water quench tower, a 
venturi scrubber, and a caustic packed-tower scrubber, which lower the 
retort off-gas temperature to an average of 80 deg. F, and a 
chlorinated brine packed-tower scrubber as the final control device. 
The following summarizes the emissions data available and our approach 
to determining MACT for non-oven type units.
    At one of the plants with a rotary kiln, the mercury concentration 
is determined daily at the outlet of the last carbon adsorber bed using 
a company-developed procedure derived from an OSHA method for 
determining worker exposures in the workplace. When submitting data 
obtained using this method, the company cautioned that although the 
routine sampling with the modified OSHA procedure produces credible 
information on relative changes in performance, it does not produce 
accurate information on actual mercury releases. Specifically, we 
believe the data obtained using this method are biased low. The average 
measured mercury concentration for this plant is an order of magnitude 
lower than averages for the other two plants (discussed below), and the 
minimum measured value is two orders of magnitude lower. It is our 
conclusion that data from this plant are unsuitable for standard 
setting, as they greatly understate emissions and thus overstate the 
performance of the mercury recovery/control system.
    At the other plant with a rotary kiln, concentration measurements 
are made monthly using a method that is a modification of EPA Method 
101 for determining mercury emissions from mercury cell chlor-alkali 
plants. Data were provided for each month in 1998. The measured mercury 
concentrations range from 1.4 mg/m3 to 6.0 mg/m3, 
with a mean of 2.8 mg/m3.
    Personnel at the plant with the single hearth retort conduct 
monthly measurements of the mercury concentration in the brine scrubber 
exhaust gas. The measurement method used is based on an EPA reference 
method and is very similar to the method used at the second rotary kiln 
plant discussed above. Data were provided for 1997, 1998, and 1999. The 
measured mercury concentrations range from 0.2 mg/m3 to 10.8 
mg/m3, with a mean and median value of 1.6 and 2.2 mg/
m3, respectively.

[[Page 44688]]

    In establishing the MACT floor and subsequently MACT, we focused on 
the two plants for which we have credible emissions data. We removed 
two points determined to be statistical outliers from the 3-year data 
set at the plant with the single hearth retort and determined there 
were no statistical outliers in the 1998 data set for the second plant 
with a rotary kiln. These data were used in the MACT determination for 
non-oven thermal recovery unit vents.
    Although there are fewer than five sources from which to constitute 
a MACT floor, we opted to take the mean of the data from these two 
plants as the MACT floor option for existing sources. We averaged the 
three highest concentration data points for each plant and took the 
mean of the two plant averages (3.9 mg/dscm and 5.4 mg/dscm) rounded to 
one significant figure, 5 mg/dscm, as the floor value.
    Of the three plants with non-oven type mercury thermal recovery 
unit vents, we project that only one plant would need to upgrade 
existing controls to meet the 5 mg/dscm floor level, and that this 
could be accomplished by replacing the carbon in its existing carbon 
adsorbers more frequently than current practice. There would be no 
capital costs as more frequent carbon media replacement is only a 
recurring annual cost estimated at $1,200 per year. Mercury emission 
reductions against actual baseline emissions would total about 2 kg/yr 
(5 lbs/yr) for the three plants. The associated annual cost per unit of 
mercury emission reduction would be approximately $240 per pound. With 
the assumption of more frequent carbon media replacement, there are no 
associated secondary air pollution, water pollution, or energy impacts. 
Estimated solid waste impacts due to increased use of carbon adsorption 
total 0.09 Mg/yr (0.1 tpy).
    We then examined beyond-the-floor MACT options. A direct comparison 
of the data for the two plants providing credible data indicates that 
the emission levels recorded at one plant (with mean and median values 
of 1.2 and 0.7 mg/m3, respectively) are about half that 
recorded at the other plant (with mean and median values of 2.8 and 1.9 
mg/m3, respectively). Further, the highest monthly values 
recorded were 4.3 mg/m3 and 5.9 mg/m3, 
respectively. We used the data from the lower-emitting plant to 
establish a beyond-the-floor option. We averaged the three highest 
values for this plant (not including the values determined to be 
outliers) for a beyond-the-floor value of 4 mg/dscm.
    Due to the very low volumetric flow rates associated with non-oven 
type mercury thermal recovery unit exhaust streams (typically less than 
about 2,000 scfm), we believe that the retrofit of control equipment to 
reduce mercury emissions is both practical and reasonable. For purposes 
of estimating impacts, we assumed that one plant would need to upgrade 
its controls, and that it would do this by further increasing its 
carbon replacement frequency to meet the 4 mg/dscm level. We assume 
that the remaining plant would not need to upgrade its existing 
controls to meet the beyond-the-floor level.
    In evaluating regulatory options that are more stringent than the 
floor, we must consider the cost of achieving such emission reduction, 
and any non-air quality health and environmental impacts and energy 
requirements. The beyond-the-floor option would result in an additional 
6 kg/yr (13 lbs/yr) of total mercury emission reductions for the three 
plants (a 10 percent incremental reduction from the floor option). The 
incremental annual costs are estimated to total around $5,800 per year. 
The incremental cost per unit of incremental mercury emission reduction 
is approximately $450 per pound. With the assumption of more frequent 
carbon media replacement, there are no associated incremental secondary 
air pollution, water pollution, or energy impacts. The estimated solid 
waste impacts total an additional 0.4 Mg/yr (0.5 tpy) of mercury-
containing spent carbon.
    We believe the additional emission reductions that would be 
achieved by the beyond-the-floor option are warranted. Further, we 
believe that the incremental costs of achieving such emission 
reductions, as well as incremental non-air environmental impacts and 
energy requirements, are reasonable for mercury. Therefore, we selected 
4 mg/dscm as MACT for non-oven type mercury thermal recovery unit 
vents.
    In summary, the proposed emission limits are 23 mg/dscm and 4 mg/
dscm for oven type mercury thermal recovery unit vents and non-oven 
type mercury thermal recovery unit vents, respectively. We believe that 
both proposed limits are representative of the best-performing systems 
for each retort type based on available data and as such, each limit 
clearly meets our statutory safeguard regarding the minimum level of 
control allowed under the statute.

E. How did We Determine the Basis and Level of the Proposed Standards 
for New Sources?

    Section 112(d)(3) of the CAA specifies that standards for new 
sources cannot be less stringent than the emission control that is 
achieved in practice by the best-controlled similar source, as 
determined by the Administrator.
    In the case of mercury cell chlor-alkali production facilities, of 
the 43 chlor-alkali production facilities in operation in the U.S. at 
the time of this analysis, 32 use cell technologies other than mercury 
(23 use diaphragm cells and 9 use membrane cells). As explained further 
below, we consider these chlor-alkali facilities using non-mercury cell 
technology to be ``similar sources,'' and, as such, a suitable basis 
for the standard for new source MACT. Such a standard would effectively 
eliminate mercury emissions from new source chlor-alkali production 
facilities.
    The impact of such a standard would be negligible given that in 
terms of cost, economic and air and non-air environmental impacts, we 
don't believe that a new mercury cell chlor-alkali plant would 
otherwise ever be constructed. No new mercury cell chlor-alkali plant 
has been constructed in the U.S. in over 30 years, and we have no 
indication of any plans for future construction. In addition, we 
believe that any future demand for new or replacement chlor-alkali 
production capacity would be met easily through the construction of new 
production facilities that do not use or emit mercury. Consequently, we 
believe it is appropriate to consider non-mercury cell facilities as 
similar sources and the prohibition of new mercury cell chlor-alkali 
production facilities achievable. Accordingly, we are proposing a 
complete prohibition on mercury emissions for new source MACT for 
mercury cell chlor-alkali production facilities. We are not proposing 
any initial and continuous compliance requirements related to this 
emission limit as we believe they are unnecessary since the emissions 
prohibition effectively precludes the new construction or 
reconstruction of a mercury cell chlor-alkali production facility.
    As highlighted in the previous discussion on the selection of 
standards for existing sources, the emission levels achieved by the 
best-controlled sources were selected as the proposed existing source 
MACT levels for mercury recovery facilities. These best levels of 
control for point sources are 23 mg/dscm of exhaust from an oven type 
mercury thermal recovery unit vent, and 4 mg/dscm of exhaust from a 
non-oven type mercury thermal recovery unit vent. For fugitive emission 
sources, the best level of control identified is the work practice 
standard represented in

[[Page 44689]]

the beyond-the-floor option selected for proposal for existing sources.
    In the case of mercury recovery facilities, we know of three plants 
that employ low emitting mercury recovery processes. These processes 
include chemical mercury recovery used at two plants and recovery in a 
batch purification still used at a third plant. Unlike thermal recovery 
units which are capable of treating a variety of waste types, the 
chemical recovery and the purification still processes have limited 
application. Both are suitable to treating only certain waste types, 
K106 wastes for the former and end-box residues for the latter. Plants 
using these nonthermal recovery processes transfer their remaining 
wastes off-site for treatment, which typically involves thermal 
recovery. Given this limitation, we do not believe that these 
nonthermal recovery processes qualify as a suitable basis for new 
source MACT. Consequently, for new source MACT for mercury recovery 
facilities, we are proposing numerical mercury emission limits 
consistent with that achieved by the best similar sources, 23 mg/dscm 
for oven type thermal recovery unit vent and 4 mg/dscm for non-oven 
type thermal recovery units.

F. How did We Select the Testing and Initial Compliance Requirements?

    We selected the proposed testing and initial and continuous 
compliance requirements based on requirements specified in the NESHAP 
General Provisions (40 CFR part 63, subpart A). These requirements were 
adopted for mercury cell chlor-alkali plants to be consistent with 
other part 63 NESHAP. These requirements were chosen to ensure that we 
obtain or have access to sufficient information to determine whether an 
affected source is complying with the standards specified in the 
proposed rule.
    The proposed rule would require initial and periodic compliance 
tests for determining compliance with the emission limits for by-
product hydrogen streams and end-box ventilation system vents, and the 
emission limits for oven type and non-oven type mercury thermal 
recovery unit vents. The proposed rule would require the use of 
published EPA methods for measuring total mercury. Specifically, the 
proposed rule would allow the use of Method 101 or 101A (of appendix A 
of 40 CFR part 61) for end-box ventilation system vents and mercury 
thermal recovery unit vents and Method 102 for by-product hydrogen 
streams. Methods 101 and 102 were developed in the 1970's specifically 
for use at mercury cell chlor-alkali plants. Although Method 101A was 
developed to measure mercury emissions from sewage sludge incinerators, 
it is appropriate for use for end-box ventilation system vents and 
mercury thermal recovery unit vents.
    The NESHAP General Provisions specify at Sec. 63.7(e)(3) that each 
test consist of three separate test runs. The proposed rule would adopt 
this requirement. Further, the proposed rule would require that each 
test run be at least 2 hours long. This is the duration specified in 
Method 101 and referenced in Methods 101A and 102.
    In the stack test data that were provided to us, there were 
numerous incidents where the results were reported as ``less than'' a 
certain level. We believe that this is primarily related to the 
sensitivity of the analytical instrument (that is, the absorption 
spectrophotometer) used to measure the amount of mercury in the 
collected sample. Method 101 states that the absorption spectrometer 
must be the ``Perkin Elmer 303, or equivalent, containing a hollow-
cathode mercury lamp and the optical cell * * * .'' It is our 
understanding that this particular model is no longer commercially 
available, and that newer, more sensitive absorption spectrophotometers 
are available. We considered whether it was necessary to specify, 
either in the proposed rule or through a modification to the test 
method, that Perkin Elmer 303 did not have to be used. We concluded 
that the ``or equivalent'' language contained in Method 101 allows for 
the use of newer, more sensitive instruments and as a result, adding 
rule language or amending Method 101 was unnecessary.
    Even with the 2-hour minimum test run period and the clarification 
that newer, more sensitive absorption spectrophotometers are allowed to 
be used, we remain concerned that quantifiable results of mercury 
emissions may not be obtained during performance tests. As a result, 
the proposed rule includes a requirement that the amount of mercury 
collected during each test run be at least 2 times the limit of 
detection for the analytical method used. This will assure that a 
reliably quantifiable amount of mercury is collected for each test run.
    The emission limits for by-product hydrogen streams and end-box 
ventilation system vents are in the form of mass of mercury emissions 
per mass of chlorine produced. Therefore, criteria for the measurement 
of chlorine production during performance testing are also necessary. 
It is our understanding that instrumentation used to measure actual 
chlorine production, as well as the location and frequency of 
measurement, varies from plant to plant. Types of instruments used 
include rail car weigh scales, weigh cells on liquid storage tanks, and 
gas flow meters. Calibration procedures for these instruments are 
plant-specific and dependent on the involvement of third parties 
concerned with quantifying actual chlorine production for billing and 
other purposes. Moreover, at a given plant, an accurate value for 
actual chlorine production based on these measurements is generally 
obtained at the end of an operating month when mass balance 
calculations are performed to verify measurements.
    For a compliance test run on the order of several hours, we, 
therefore, needed to rely on some other reasonable indicator of 
chlorine production. All mercury cell chlor-alkali plants measure the 
electric current through on-line mercury cells, also known as the cell 
line load or cell line current load, with a digital monitor that 
provides readings continuously. This cell line current load measurement 
can be used in conjunction with a theoretical chlorine production rate 
factor to obtain the instantaneous chlorine production rate. The 
theoretical factor is based on a statement of Faraday's Law that 96,487 
Coulombs (Faraday's constant, where a Coulomb is a fundamental unit of 
electrical charge) are required to produce one gram equivalent weight 
of the electrochemical reaction product (chlorine). It is our 
understanding that chlorine production calculated in this manner would 
differ from the actual quantity produced at the plant by about 3 to 7 
percent due to electrical conversion efficiency and reaction efficiency 
determined by equipment characteristics and operating conditions. We 
consider this degree of variability acceptable.
    We, therefore, stipulate in the proposed rule that the cell line 
current load be continuously measured during a performance test run and 
that measurements be recorded at least every 15 minutes over the 
duration of the test run. We further specify equations for computing 
the average cell line current load and for calculating the quantity of 
chlorine produced over the test run.
    In addition to the requirement to conduct performance tests to 
demonstrate compliance with the emission limits, owners or operators 
would be required to establish a mercury concentration operating limit 
for each vent as part of the initial compliance demonstration. Then, at 
least twice a permit term (at mid-term and renewal), they would conduct 
subsequent compliance demonstrations and at the same time reestablish

[[Page 44690]]

operating limit values. The proposed rule would require that these 
mercury concentration operating limits be determined directly from the 
concentration monitoring data collected concurrent with the initial 
performance test.
    For the work practice standards, initial compliance is demonstrated 
by documenting and certifying that the standards are being met or will 
be met by submitting a washdown plan and by certifying that the plan is 
being followed or will be followed. This approach assures initial 
compliance by requiring the owner or operator to submit a certified 
statement in the Notification of Compliance Status report.

G. How Did We Select the Continuous Compliance Requirements?

    For each of the proposed emission limits, which consist of the 
limits on mercury emissions from hydrogen streams, end-box ventilation 
systems, and thermal recovery units, we considered the feasibility and 
suitability of continuous emission monitors (CEM) as the means of 
demonstrating continuous compliance. While we were unable to identify 
any mercury cell chlor-alkali plant currently using a mercury CEM on 
any vent, we did determine that there are mercury CEM commercially 
available that may be suitable for use at mercury cell chlor-alkali 
plants. To date, most of the development work on mercury CEM has 
focused on the development of monitors for the continuous measurement 
of mercury air emissions from either coal-fired utility boilers or 
hazardous waste incinerators. Most mercury CEM are extractive monitors 
which extract a continuous or nearly continuous sample of gas, then 
transfer the gas to an instrument for spectroscopic analysis by way of 
either cold vapor atomic absorption or cold vapor atomic fluorescence.
    These cold vapor techniques have similar limitations. Both detect 
mercury vapor only in its elemental form. To measure other forms of 
mercury vapor (e.g., oxidized/inorganic/divalent mercury, such as 
mercuric chloride), the sampled gases must first pass through a 
converter which reduces any nonelemental mercury vapor present to the 
elemental form prior to analysis. None of the available monitors based 
on the cold vapor techniques are capable of measuring particulate or 
nonvapor phase mercury since the sample gas must be filtered to remove 
any particulate matter present prior to conversion and analysis. This 
would include elemental mercury condensed on particulate matter and any 
mercury compounds in particulate form. Monitors that are capable of 
measuring total vapor phase mercury range in price from $50,000 to 
$80,000. Simpler monitors that measure only elemental mercury vapor 
average about $10,000.
    For the proposed emission limits for by-product hydrogen streams 
and end-box ventilation system vents, which are expressed in grams of 
mercury per megagram of chlorine produced, we evaluated two options: 
continuous compliance against the proposed gram per megagram standards, 
and continuous compliance against plant and vent specific operating 
limits expressed in terms of concentration. In addition to monitoring 
mercury concentration, the first option would require continuous 
monitoring of volumetric flow rate and a continuous, or at least 
periodic, measurement of chlorine production. The operating limits for 
the second option would be set at the time that initial compliance with 
the emission limit is demonstrated.
    Since the predominant form of liquid mercury in mercury cells and 
other production facilities is elemental, we assumed that the mercury 
contained in the vent gas from either by-product hydrogen streams or 
end-box ventilation system vents is similarly largely in the elemental 
vapor form. Thus, the simpler, less expensive monitors for measuring 
elemental mercury vapor only should be suitable.
    We concluded that monitoring only elemental mercury concentration 
provides a simpler, less expensive, and more reliable alternative to 
demonstrating continuous compliance than monitoring against the gram 
per megagram standards. As a result, we are proposing that continuous 
compliance for by-product hydrogen streams and end-box ventilation 
system vents be demonstrated through the continuous monitoring of 
elemental mercury concentration in the vent exhaust.
    To the best of our knowledge, mercury contained in the exhaust gas 
of thermal recovery units, both oven and non-oven types, should exist 
as both vapor (elemental or nonelemental) and fine particulate matter. 
As highlighted above, none of the currently available monitors are 
capable of measuring particulate mercury. Consequently, continuous 
monitoring to demonstrate continuous compliance with the total mercury 
concentration limit would not be possible.
    Similar to the by-product hydrogen streams and end-box ventilation 
system vents, we also considered the feasibility and usefulness of 
monitoring vapor phase mercury, specifically the elemental form. We 
concluded that the continuous monitoring of elemental mercury vapor as 
a surrogate to the total mercury emission limit using the simpler of 
the available monitors provides an acceptable and cost-effective means 
of tracking relative changes in emissions and control device 
performance. Therefore, as proposed for by-product hydrogen streams and 
end-box ventilation system vents, we are proposing for oven type and 
non-oven type mercury thermal recovery units that continuous compliance 
be demonstrated through continuous monitoring of elemental mercury 
concentration against an applicable concentration operating limit 
established as part of the initial compliance demonstration.
    Another important aspect of continuous compliance is the time 
period over which continuous compliance is determined. One option would 
be an instantaneous period, where any measurement outside of the 
established range (that is, above the established concentration limit) 
would constitute a deviation. More commonly, the average of the 
monitoring data over a specified time period, for example an hour, is 
compared to the established limit.
    While mercury cell chlor-alkali production facilities are generally 
operated continuously, there are process fluctuations that impact 
emissions. Mercury recovery facilities are operated intermittently, 
depending on the amount of mercury-containing waste to be treated and 
other factors. We believe that an emissions averaging period is 
necessary for both situations. We considered a daily averaging period 
and concluded that daily averaging would accommodate process variations 
while precluding avoidable periods of high emissions. Therefore, we are 
proposing a daily averaging period for demonstrating continuous 
compliance.
    We also considered how to address monitoring data collected during 
startups, shutdowns, and malfunctions. We believe that it is important 
to continue to monitor the outlet mercury concentration during 
startups, shutdowns, and malfunctions to minimize emissions and to 
demonstrate that the plant's startup, shutdown, and malfunction plan is 
being followed. However, as provided for in the NESHAP General 
Provisions (40 CFR part 63, subpart A), we do not believe that the data 
collected during these periods should be used in calculating the daily 
average values. The emission limits were developed based on normal 
operation, and the performance tests will be conducted during 
representative operating conditions. Therefore, the

[[Page 44691]]

inclusion of monitoring data collected during startups, shutdowns, and 
malfunctions into the daily averages would be inconsistent with the 
data used to develop the emission limits and, subsequently, the mercury 
concentration operating limits.
    While we did not identify situations in the mercury cell chlor-
alkali industry where elemental mercury concentration is being 
continuously monitored, we believe that continuous elemental mercury 
concentration monitoring devices are available for use at mercury cell 
chlor-alkali plants. We recognize that the transfer of this monitoring 
technology to applications at mercury cell chlor-alkali plants will 
introduce uncertainties that can only be addressed through actual field 
demonstration. We are specifically requesting comment on the technical 
feasibility of using continuous elemental mercury concentration 
monitors for indicating relative changes in control system performance. 
We are also requesting comment on the proposed specifications for these 
devices.
    Continuous compliance with the proposed work practice standards for 
the fugitive emission sources would be demonstrated by maintaining the 
required records documenting conformance with the standards and by 
maintaining the required records showing that the washdown plan was 
followed.

H. How Did We Select the Notification, Recordkeeping, and Reporting 
Requirements?

    We selected the proposed notification, recordkeeping, and reporting 
requirements based on requirements specified in the NESHAP General 
Provisions (40 CFR part 63, subpart A). As with the proposed initial 
and continuous compliance requirements, these requirements were adapted 
for mercury cell chlor-alkali plants to be consistent with other part 
63 national emission standards.

IV. Summary of Environmental, Energy, Cost, and Economic Impacts

A. What Are the Air Emission Impacts?

    As discussed previously, the level of mercury emissions allowed by 
the Mercury NESHAP is 2,300 grams per day. If one assumes that all 
twelve plants in the source category emit mercury at this level and 
that each operates 365 days a year, total annual potential-to-emit 
baseline emissions would be 10,074 kg/yr (22,200 lb/yr). Annual 
potential-to-emit baseline emissions for fugitive emission sources 
would be 5,694 kg/yr (12,544 lb/yr), based on 1,300 grams per day 
assumed for each plant's cell room ventilation system when the eighteen 
design, maintenance, and housekeeping practices referenced in the 
Mercury NESHAP are followed. Annual potential-to-emit baseline 
emissions for by-product hydrogen streams, end-box ventilation system 
vents, and mercury thermal recovery unit vents would be 4,380 kg/yr 
(9,656 lb/yr), based on the remaining 1,000 grams per day allowed. We 
estimate that the proposed rule would reduce industrywide mercury 
emissions for by-product hydrogen streams, end-box ventilation system 
vents, and mercury thermal recovery unit vents from this annual 
potential-to-emit baseline to around 245 kg/yr (545 lb/yr), which is 
equivalent to about 94 percent reduction.
    While the level of mercury emissions allowed by the Mercury NESHAP 
defines the potential-to-emit baseline, the sum of annual mercury 
emissions releases from by-product hydrogen streams, end-box 
ventilation system vents, and mercury thermal recovery vents, as 
estimated by mercury cell chlor-alkali plants, defines an annual actual 
baseline for vents of about 935 kg/yr (2,060 lb/yr). We estimate that 
the proposed rule would reduce industrywide mercury emissions for vents 
from this annual actual baseline to around 245 kg/yr (545 lb/yr), which 
is equivalent to about 74 percent reduction.
    We estimate that secondary air pollution emissions would result 
from the production of electricity required to operate new control 
devices and new monitoring equipment assumed for plant vents. Assuming 
electricity production as based entirely on coal combustion for a 
worst-case scenario, we estimated plant-specific impacts for carbon 
dioxide, sulfur dioxide, nitrogen oxides, particulate matter, and 
carbon monoxide emissions. The total estimated secondary air impacts of 
the proposed requirements for point sources at the twelve mercury cell 
chlor-alkali plants is around 554 Mg/yr (611 tpy) for all pollutants 
combined, with carbon dioxide emissions comprising 99 percent of the 
estimate.
    We are unable to quantify the primary air emission impacts 
associated with the proposed work practice standards, so no mercury 
emission reduction is assumed for fugitive emission sources. However, 
we believe strongly that the new and more explicit requirements 
contained in the proposed standards will in fact result in mercury 
emission reductions beyond baseline levels. Relative to secondary 
impacts, we expect that secondary air pollution emissions, principally 
carbon dioxide, would result from the production of electricity 
required to operate new monitoring equipment assumed for plant cell 
rooms. We estimate the secondary air impacts of the proposed rule for 
fugitive sources to be 17 Mg/yr (19 tpy).

B. What Are the Non-Air Health, Environmental, and Energy Impacts?

    We do not expect that there will be any significant adverse non-air 
health impacts associated with the proposed standards for mercury-cell 
chlor-alkali plants.
    We estimate that an increase in the amount of mercury-containing 
waters would result from the heightened use of packed tower scrubbing 
assumed for several plant vents. The total estimated water pollution 
impact of the proposed rule for point sources is about 1.8 million 
liters (466 thousand gallons) of additional wastewater per year. We 
estimate that an increase in the amount of mercury-containing solid 
wastes would result with the heightened use of carbon adsorption 
assumed for several plant vents. The total estimated solid waste impact 
of the proposed rule for point sources is about 34 Mg/yr (38 tpy) of 
additional mercury-containing spent carbon.
    We are unable to quantify non-air environmental impacts associated 
with the proposed work practice standards, so no wastewater and solid 
waste impacts are assumed for fugitive emission sources.
    We estimate that the proposed requirements for point sources would 
result in increased energy consumption, specifically additional fan 
power in conveying gas streams through new carbon adsorbers and new 
packed scrubbers assumed for certain plant vents and additional power 
consumed by new vent monitoring equipment. The total estimated energy 
impacts of the proposed requirements for point sources is about 1,724 
thousand kW-hr/yr.
    We estimate that the proposed requirements for fugitive sources 
would result in increased energy consumption required to operate new 
monitoring equipment assumed for plant cell rooms. The total estimated 
energy impacts of the proposed requirements for fugitive sources is 
about 53 thousand kW-hr/yr.

C. What Are the Cost and Economic Impacts?

    For projecting cost impacts of the proposed rule on the mercury 
cell chlor-alkali industry, we estimate that all twelve plants would 
incur costs to meet the proposed work practice standards and the 
proposed monitoring,

[[Page 44692]]

recordkeeping, and reporting requirements. We estimate that ten plants 
would incur costs to meet the proposed emission limits for by-product 
hydrogen streams and end-box ventilation system vents, and three plants 
would incur costs to meet the proposed emission limits for mercury 
thermal recovery units. The total estimated capital cost of the 
proposed rule for the twelve mercury cell chlor-alkali plants is around 
$2.5 million, and the total estimated annual cost is about $2.2 million 
per year. Plant-specific annual costs in our estimate range from about 
$91,000 for the least-impacted plant to about $375,000 for the worst-
impacted plant.
    The purpose of the economic impact analysis is to estimate the 
market response of chlor-alkali production facilities to the proposed 
standards and to determine the economic effects that may result due to 
the proposed NESHAP. Chlor-alkali production jointly creates both 
chlorine and caustic, usually sodium hydroxide, in fixed proportions. 
Being joint commodities, the economic analysis considers the impacts of 
the proposed NESHAP on both the chlorine and sodium hydroxide markets.
    The chlorine production source category contains 43 facilities, but 
only twelve facilities using mercury cells are directly affected by the 
proposed standards. These twelve facilities are located at twelve 
plants that are owned by eight companies. Although one of these twelve 
plants permanently closed due to reasons unrelated to this rulemaking, 
the following impacts are based on the twelve plants in operation at 
the time the analysis was conducted.
    Chlor-alkali production in mercury cells leads to potential mercury 
emissions from hydrogen streams, end-box ventilation system vents, 
mercury thermal recovery units, and fugitive emission sources. The 
compliance costs for the proposed standards, therefore, relate to the 
purchase, installation, operation, and maintenance of pollution control 
equipment at the point sources, as well as the labor costs and 
overheads associated with observing work practices addressing fugitive 
emissions. The estimated total annual costs for the proposed NESHAP are 
$1.8 million. This cost estimate represents about 0.38 percent of the 
1997 chlorine sales revenue for the twelve mercury cell chlor-alkali 
production facilities. Furthermore, the total annual costs represent 
only 0.01 percent of the revenues of owning the directly affected 
mercury cell chlor-alkali plants.
    The economic analysis predicts minimal changes in industry outputs 
and the market prices of chlorine and sodium hydroxide as a result of 
the estimated control costs. The new market equilibrium quantities of 
chlorine and sodium hydroxide decrease by less than 0.1 percent. 
Equilibrium prices of chlorine and sodium hydroxide both rise by less 
than 0.1 percent due to the proposed standards. Based on these 
estimates, we conclude that the proposed standards are not likely to 
have a significant economic impact on the chlorine production industry 
as a whole or on secondary markets such as the labor market and foreign 
trade.
    We perform an economic analysis to determine facility- and company-
specific impacts. These economic impacts are measured by calculating 
the ratio of the estimated annualized compliance costs of emissions 
control for each entity to its revenues (i.e., cost-to-sales ratio). 
After the cost-to-sales ratio is calculated for each entity, it is then 
multiplied by 100 to convert the ratio into percentages. Actual 
revenues at the facility level are not available, therefore, estimated 
facility revenues received from the sale of chlorine are used. Some of 
these facilities also produce caustic as potassium hydroxide, but the 
revenues from the sale of this product are not estimated. The twelve 
mercury cell chlor-alkali plants have positive cost-to-sales ratios. 
The ratio of costs to estimated chlorine sales revenue for these 
facilities range from a low of 0.16 percent to a high of 1.00 percent. 
The average cost-to-sales ratio for the twelve mercury process chlorine 
production facilities is 0.46 percent. More detailed economic analysis 
predicted minimal changes in chlorine production at each facility. 
Thus, overall, the economic impact of the proposed standards is minimal 
for the facilities producing chlorine.
    The share of compliance costs to company sales are calculated to 
determine company level impacts. Since eight companies own the twelve 
affected facilities, all eight firms face positive compliance costs 
from the proposed NESHAP. The ratio of costs to estimated revenues 
range from a low of less than 0.01 percent to a high of 0.22 percent, 
and the average ratio of costs to company revenues is 0.06 percent. 
Again, more detailed economic analysis at the company level predicts 
little change in company output or revenues. So, at the company level, 
the proposed standards are not anticipated to have a significant 
economic impact on companies that own and operate the chlorine 
production facilities.
    No facility or company is expected to close as a result of the 
proposed standards, and the economic impacts to consumers are 
anticipated to be minimal. The generally small scale of the impacts 
suggests that there will also be no significant impacts on markets for 
the products made using chlorine or sodium hydroxide. For more 
information, consult the economic impact analysis report entitled 
``Economic Impact Analysis for the Proposed Mercury Cell Chlor-Alkali 
Production NESHAP,'' which is available in the docket to this 
rulemaking.

V. Solicitation of Comments and Public Participation

    We seek full public participation in arriving at final decisions 
and encourage comments on all aspects of the proposed standards from 
all interested parties. You need to submit appropriate supporting data 
and analyses with your comments to allow us to make the best use of 
them. Be sure to direct your comments to the Air and Radiation Docket 
and Information Center, Docket No. A-2000-32 (see ADDRESSES).

VI. Administrative Requirements

A. Executive Order 12866, Regulatory Planning and Review

    Under Executive Order 12866 (58 FR 51735, October 4, 1993), the EPA 
must determine whether the regulatory action is ``significant'' and, 
therefore, subject to review by the Office of Management and Budget 
(OMB) and the requirements of the Executive Order. The Executive Order 
defines ``significant regulatory action'' as one that OMB determines is 
likely to result in a rule that may:
    (1) Have an annual effect on the economy of $100 million or more or 
adversely affect in a material way the economy, a sector of the 
economy, productivity, competition, jobs, the environment, public 
health or safety, or State, local, or Tribal governments or 
communities;
    (2) Create a serious inconsistency or otherwise interfere with an 
action taken or planned by another agency;
    (3) Materially alter the budgetary impact of entitlements, grants, 
user fees, or loan programs or the rights and obligations of recipients 
thereof; or
    (4) Raise novel legal or policy issues arising out of legal 
mandates, the President's priorities, or the principles set forth in 
this Executive Order.
    Pursuant to the terms of Executive Order 12866, it has been 
determined that the proposed rule is not a ``significant regulatory 
action'' because none of the listed criteria apply to this action. 
Consequently, this action was not submitted to OMB for review under 
Executive Order 12866.

[[Page 44693]]

B. Executive Order 13132 (Federalism)

    Executive Order 13132, entitled ``Federalism'' (64 FR 43255, August 
10, 1999), requires the EPA to develop an accountable process to ensure 
``meaningful and timely input by State and local officials in the 
development of regulatory policies that have federalism implications.'' 
``Policies that have federalism implications'' is defined in the 
Executive Order to include rules that have ``substantial direct effects 
on the States, on the relationship between the national government and 
the States, or on the distribution of power and responsibilities among 
the various levels of government.'' Under section 6 of Executive Order 
13132, the EPA may not issue a rule that has federalism implications, 
that imposes substantial direct compliance costs, and that is not 
required by statute, unless the Federal government provides the funds 
necessary to pay the direct compliance costs incurred by State and 
local governments, or the EPA consults with State and local officials 
early in the process of developing the rule. The EPA also may not issue 
a rule that has federalism implications and that preempts State law 
unless the Agency consults with State and local officials early in the 
process of developing the rule.
    If the EPA complies by consulting, Executive Order 13132 requires 
the EPA to provide to OMB, in a separately identified section of the 
preamble to the rule, a federalism summary impact statement (FSIS). The 
FSIS must include a description of the extent of the EPA's prior 
consultation with State and local officials, a summary of the nature of 
their concerns and the Agency's position supporting the need to issue 
the rule, and a statement of the extent to which the concerns of State 
and local officials have been met. Also, when the EPA transmits a draft 
final rule with federalism implications to OMB for review pursuant to 
Executive Order 12866, the EPA must include a certification from the 
Agency's Federalism Official stating that the EPA has met the 
requirements of Executive Order 13132 in a meaningful and timely 
manner.
    The proposed rule will not have substantial direct effects on the 
States, on the relationship between the national government and the 
States, or on the distribution of power and responsibilities among the 
various levels of government, as specified in Executive Order 13132. 
The proposed rule is mandated by statute and does not impose 
requirements on States; however, States will be required to implement 
the rule by incorporating the rule into permits and enforcing the rule 
upon delegation. States will collect permit fees that will be used to 
offset the resource burden of implementing the rule. Thus, the 
requirements of section 6 of the Executive Order do not apply to the 
proposed rule. Although section 6 of Executive Order 13132 does not 
apply to the proposed rule, the EPA did consult with State and local 
officials in developing the proposed rule.

C. Executive Order 13175, Consultation and Coordination with Indian 
Tribal Governments

    Executive Order 13175, entitled ``Consultation and Coordination 
with Indian Tribal Governments'' (65 FR 67249, November 6, 2000), 
requires the EPA to develop an accountable process to ensure 
``meaningful and timely input by tribal officials in the development of 
regulatory policies that have tribal implications.'' ``Policies that 
have tribal implications'' is defined in the Executive Order to include 
regulations that have ``substantial direct effects on one or more 
Indian tribes, on the relationship between the Federal government and 
the Indian tribes, or on the distribution of power and responsibilities 
between the Federal government and Indian tribes.''
    The proposed rule does not have tribal implications. It will not 
have substantial direct effects on tribal governments, on the 
relationship between the Federal government and Indian tribes, or on 
the distribution of power and responsibilities between the Federal 
government and Indian tribes, as specified in Executive Order 13175. 
Thus, Executive Order 13175 does not apply to the proposed rule.
    In the spirit of Executive Order 13175 and consistent with EPA 
policy to promote communications between EPA and tribal governments, 
EPA specifically solicits additional comment on the proposed rule from 
tribal officials.

D. Executive Order 13045, Protection of Children From Environmental 
Health Risks and Safety Risks

    The Executive Order 13045 applies to any rule (1) that OMB 
determines is ``economically significant,'' as defined under Executive 
Order 12866, and (2) the EPA determines that the environmental health 
or safety risk addressed by the rule has a disproportionate effect on 
children. If the regulatory action meets both criteria, the EPA must 
evaluate the environmental, health, or safety aspects relevant to 
children and explain why the rule is preferable to other potentially 
effective and reasonably feasible alternatives considered by the EPA.
    As with most rulemakings developed under section 112(d) of the CAA, 
today's proposal is based on MACT. Risks to public health and impacts 
on the environment are not typically considered in the development of 
emissions standards under section 112(d). Rather, these risks and 
impacts are considered later (within 8 years after promulgation of the 
MACT rule) under the residual risk program as required by section 
112(f) of the CAA. While we do not believe the proposed rule to be 
``economically significant,'' as defined under Executive Order 12866, 
we do believe that it addresses environmental health or safety risks 
that may have a disproportionate effect on children.
    Mercury has been identified as a priority pollutant under EPA's 
National Agenda to Protect Children's Health from Environmental Threats 
and by the Federal Children's Health Protection Advisory Committee 
(CHPAC). The CHPAC was formed to advise, consult with, and make 
recommendations to the EPA on issues associated with the development of 
regulations to address the prevention of adverse health effects to 
children. One of the CHPAC's primary missions was to identify five 
existing EPA regulations, which if reevaluated, could lead to better 
protection for children. The CHPAC recommended the Mercury NESHAP for 
chlor-alkali plants as one of the regulations to be reevaluated 
considering impacts on children. We adopted the CHPAC recommendation. 
Therefore, we have considered the impacts on children in the 
development of the proposed rule. A qualitative assessment of the 
potential impacts on children's health due to mercury emissions from 
chlor-alkali plants is presented here.
1. What Is Mercury and How Is It Transported in the Environment?
    Mercury is a naturally occurring element found in air, water and 
soil. Mercury is found in various inorganic and organic forms in the 
environment. The three primary forms of interest for this assessment 
are: elemental mercury, inorganic or divalent mercury, and 
methylmercury. Based on available information, it appears that most of 
the mercury emitted from chlor-alkali plants is in the elemental form, 
and a small percentage is in the divalent form. The air transport and 
deposition patterns of mercury emissions depend on various factors 
including the chemical form of mercury emitted, stack height, 
characteristics of the area surrounding the site, topography, and

[[Page 44694]]

meteorology. As it moves through environmental media (e.g., air, 
sediments, water), mercury undergoes complex transformations.
    Mercury is highly toxic, persistent, and bioaccumulates in the food 
chain. The mercury emitted to the air from various types of sources 
(usually in elemental or divalent forms) transports through the 
atmosphere and eventually deposits onto land or water bodies. The 
deposition can occur locally near the source or at long distances 
(e.g., hundreds or thousands of miles away). Once deposited, the 
chemical form of mercury can change (through a methylation process) 
into methylmercury (MeHg), which biomagnifies in the aquatic food 
chain. As reported in the 1997 EPA Mercury Study, nearly all of the 
mercury that accumulates in fish is MeHg. Generally, fish consumption 
dominates the pathway for human and wildlife exposure to mercury. As of 
July 2000, 40 States have issued fish advisories for mercury. Thirteen 
of these States have issued advisories for all water bodies in their 
State, and the other 27 States have issued advisories for over 1,900 
specific water bodies.
2. What Are the Health Effects of the Various Mercury Compounds?
    The health effects of the various mercury compounds were discussed 
earlier. Methylmercury is discussed further in this section because it 
is the primary form for which the general U.S. population is exposed.
    Neurotoxicity is the health effect of greatest concern with MeHg 
exposure. The developing fetus is considered most sensitive to the 
effects from MeHg. Therefore, women of child-bearing age are the 
population of greatest concern. Some offspring born of women exposed to 
relatively high doses of MeHg during pregnancy exhibited a variety of 
developmental neurological abnormalities, including delayed onset of 
walking and talking, cerebral palsy, and reduced neurological test 
scores. Far lower in utero exposures have resulted in delays and 
deficits in learning abilities. It is also possible that children 
exposed after birth are also potentially more sensitive to the toxic 
effects of MeHg than adults because their nervous systems are still 
developing.
    Extrapolating from high-dose exposure incidents, we derived a 
reference dose (RfD) for MeHg of 0.1 microgram per kilogram body weight 
per day (0.1 ug/kg/day) based on developmental neurological effects 
observed in children born to mothers who were exposed to MeHg during 
pregnancy. The RfD is an estimated daily ingestion level anticipated to 
be without adverse effect to persons, including sensitive 
subpopulations, over a lifetime. At the RfD or below, exposures are 
expected to be safe. The risks following exposures above the RfD are 
uncertain, but the potential for adverse health effects increases as 
exposures to MeHg increase. The National Academy of Sciences (NAS), in 
its July 2000 report ``Toxicological Effects of Methylmercury'' (NAS, 
2000), affirmed our assessment of MeHg toxicity and the level of our 
RfD.
3. What Are the Human Exposures to MeHg and the Potential Health 
Impacts?
    The results of dietary surveys indicate that most of the U.S. 
population consumes fish and is exposed to some MeHg as a result. The 
typical fish consumer (who eats moderate amounts of fish from 
restaurants and grocery stores) in the U.S. is not likely to be at risk 
of consuming harmful levels of MeHg; however, people who eat more fish 
than is typical or eat fish that are more contaminated than typical 
fish may be at risk. Furthermore, certain groups, such as pregnant 
women and their fetuses, young children, and subsistence fish-eating 
populations may be at particular risk.
    Based on an exposure assessment presented in the 1997 EPA Mercury 
Study, we estimate that about 7 percent of women of childbearing age 
(i.e., between the ages of 15 and 44 years) in the U.S. are exposed to 
MeHg at levels exceeding the RfD, and about 1 percent of women have 
MeHg exposures 3 to 4 times this level. Moreover, the NAS estimated in 
their recent report that over 60,000 children born each year in the 
U.S. are at risk for adverse neurological effects due to in utero 
exposure to MeHg (NAS, 2000). These exposure estimates are also 
supported by a recent study by the U.S. Center's for Disease Control 
and Prevention (CDC) on mercury levels in women of childbearing age as 
measured in hair and blood. The results of that study (which were 
published in the CDC's Morbidity and Mortality Weekly Report on March 
2, 2001) show that about 10 percent of women of childbearing age in the 
U.S. are exposed to mercury at levels above the EPA's RfD.
    Methylmercury exposure rates on a per body weight basis among 
children are predicted to be higher than for adults. The EPA estimates 
that about 25 percent of children are exposed to MeHg through 
consumption of fish at levels exceeding the RfD, and 5 percent of 
children have MeHg exposures 2 to 3 times this level (EPA, 1997).
    Most of the mercury currently entering U.S. water bodies and 
contaminating fish is the result of air emissions which, following 
atmospheric transport, deposit onto watersheds or directly to water 
bodies. We have concluded that there is a plausible link between 
emissions of mercury from anthropogenic sources (including chlor-alkali 
plants) and MeHg in fish. Waste water discharges also contribute to 
environmental loadings, but to a much lesser degree than air emissions. 
Based on modeling conducted for the 1997 EPA Mercury Study, we estimate 
that roughly 60 percent of the total mercury deposited in the U.S. 
comes from U.S. anthropogenic air emission sources; this percentage is 
estimated to be even higher in certain regions (e.g., Northeast U.S.). 
The remainder of the deposited mercury comes from natural emission 
sources, re-emissions of historic global anthropogenic mercury 
releases, and from current anthropogenic sources outside the U.S.
    We predict that increased mercury deposition will lead to increased 
levels of MeHg in fish, and that increased levels in fish will lead to 
toxicity in fish-eating birds and mammals, including humans. The NAS, 
in its July 2000 report, stated that ``because of the beneficial 
effects of fish consumption, the long-term goal needs to be a reduction 
in the concentrations of methylmercury in fish.'' We agree with this 
goal and believe that reducing emissions of mercury from various 
anthropogenic sources is an important step toward achieving this goal.
4. What Is the Effect of Mercury Emissions From Chlor-Alkali Plants?
    The majority of the mercury emitted from chlor-alkali plants is in 
the elemental form, with a much smaller percent in the divalent form. 
As stated above, fish consumption generally dominates the pathway for 
human and wildlife exposure to mercury. However, for people living 
close to chlor-alkali plants, other exposure pathways may be 
significant. Appreciable exposures to elemental mercury and divalent 
mercury may occur through inhalation. Likewise, exposures to divalent 
mercury and MeHg may occur through ingestion of contaminated soils or 
plants. Based on modeling conducted for the 1997 EPA Mercury Study, we 
estimate that mercury levels in multiple environmental media (air, 
soil, water, plants, and fish) near a typical chlor-alkali plant could 
be elevated above background levels. We also estimate that exposures 
for people living near these facilities could be higher than for people 
living further away. The extent of

[[Page 44695]]

exposures for people living near these plants will depend on various 
factors, including local terrain and meteorology, personal life style, 
activity patterns, and consumption patterns.
    We admit there are uncertainties regarding the extent of the risks 
due to mercury emissions from specific anthropogenic cources. For 
example, there is no quantification of how much of the MeHg in fish 
consumed by the U.S. population is due to emissions from chlor-alkali 
plants relative to other mercury sources e.g., natural and other 
anthropogenic sources--. Nonetheless, chlor-alkali plants re 
significant sources of mercury emissions which contribute to the 
environmental loadings and to the exposures for humans.
5. What Are the Effects of Aggregate Exposures?
    People living lcose to chlor-alkali plants could be exposed to 
elemental or divalent at elevated levels through inhalation f 
contaminated air and exposed to some divalent mercury and MeHg through 
ingestion of home grown plants. If these same people consumed fish from 
local ponds, they would be exposed to additional quantities of MeHg. 
These exposure pathways could be additional to those exposures more 
commonly experienced in the general U.S. populations such as through 
the consumption of various commercial fish (e.g., tuna, pollack, 
swordfish) and from dental fillings containing mercury amalgams. These 
exposures are also, because of mercury's half-life in the human body, 
additional to some portion of a person's previous mercury exposures. 
For people living close to chlor-alkali plants, this combination f 
sources may lead to elevated mercury exposures and body burdens. The 
degree or extent to which this occurs will largely depend on 
lifestyles, consumption patterns and other characteristics of this 
population.
6. What are the Exposures and Risks For Children?
    Exposures for children could be greater than exposures for adults 
because children consume more food and breathe more air per body weight 
than adults. Children are also potentially more sensitive to the toxic 
effects of mercury than adults because their nervous systems are still 
developing. In addition, exposures to MdHg for women who are pregnant, 
or who may become pregnant, are of particular concern because of 
potential effects on the developing fetus.
7. How Do Chlor-Alkali Plant Emissions Contribute to Global Mercury 
levels?
    Mercury is a globa pollutant. Emissions, expecially those in the 
elemental form, can transport very long distances and become part of 
the global pool. In addition to their potential contributions to 
mercury exposures locally, chlor-alkali plants are one of the many 
sources contributing to the global pool and to overall mercury levels 
in the environment.
8. How Did the EPA Consider Impacts on Children's Health in the 
Development of Today's Proposed Rule?
    Partly due to our concerns for children's health protection, we 
have strived to develop the proposed rule such that it will result in 
the greatest emissions reductions that are, consistent with section 
112(d) of the CAA, currently technically and economically feasible. 
Today's proposed rule is based on the best available control 
technologies and stringent management practices. The emissions 
reductions achieved through the proposed rule will help reduce the 
mercury exposures to humans, including children.

E. Unfunded Mandates Reform Act of 1995

    Title II of the Unfunded Mandates Reform Act of 1995 (UMRA), Public 
Law 104-4, establishes requirements for Federal agencies to assess the 
effects of their regulatory actions on State, local, and tribal 
governments and the private sector. Under section 202 of the UMRA, the 
EPA generally must prepare a written statement, including a cost-
benefit analysis, for proposed and final rules with ``Federal 
mandates'' that may result in expenditures by State, local, and Tribal 
governments, in aggregate, or by the private sector, of $100 million or 
more in any 1 year. Before promulgating an EPA rule for which a written 
statement is needed, section 205 of the UMRA generally requires the EPA 
to identify and consider a reasonable number of regulatory alternatives 
and adopt the least costly, most cost-effective, or least burdensome 
alternative that achieves the objectives of the rule. The provisions of 
section 205 do not apply when they are inconsistent with applicable 
law. Moreover, section 205 allows the EPA to adopt an alternative other 
than the least costly, most cost-effective, or least burdensome 
alternative if the Administrator publishes with the final rule an 
explanation as to why that alternative was not adopted. Before the EPA 
establishes any regulatory requirements that may significantly or 
uniquely affect small governments, including Tribal governments, it 
must have developed under section 203 of the UMRA, a small government 
agency plan. The plan must provide for notifying potentially affected 
small governments, enabling officials of affected small governments to 
have meaningful and timely input in the development of EPA regulatory 
proposals with significant Federal intergovernmental mandates, and 
informing, educating, and advising small governments on compliance with 
the regulatory requirements.
    The EPA has determined that the proposed rule does not contain a 
Federal mandate that may result in expenditures of $100 million or more 
for State, local, and Tribal governments, in the aggregate, or the 
private sector in any 1 year. The maximum total annual cost of the 
proposed rule for any year has been estimated to be less than about 
$2.5 million. Thus, today's proposed rule is not subject to the 
requirements of sections 202 and 205 of the UMRA. In addition, the EPA 
has determined that the proposed rule contains no regulatory 
requirements that might significantly or uniquely affect small 
governments because it contains no requirements that apply to such 
governments or impose obligations upon them. Therefore, today's 
proposed rule is not subject to the requirements of section 203 of the 
UMRA.
    Because the proposed rule does not include a Federal mandate and is 
estimated to result in expenditures less than $100 million in any 1 
year by State, local, and Tribal governments, the EPA has not prepared 
a budgetary impact statement or specifically addressed the selection of 
the least costly, most cost-effective, or least burdensome alternative. 
In addition, because small governments will not be significantly or 
uniquely affected by the proposed rule, the EPA is not required to 
develop a plan with regard to small governments. Therefore, the 
requirements of the UMRA do not apply to this action.

F. Regulatory Flexibility Act (RFA), as Amended by the Small Business 
Regulatory Enforcement Fairness Act of 1996 (SBREFA)

    The RFA generally requires that an agency conduct a regulatory 
flexibility analysis of any rule subject to notice and comment 
rulemaking requirements under the Administrative Procedure Act or any 
other statute unless the agency certifies that the rule will not have a 
significant economic impact on a substantial number of small entities. 
Small entities include small businesses,

[[Page 44696]]

small organizations, and small governmental jurisdictions.
    For purposes of assessing the impacts of today's proposed rule on 
small entities, small entity is defined as: (1) A small business with 
less than 1,000 employees, (according to the Small Business 
Administration definition of a small business in SIC 2812); (2) a small 
governmental jurisdiction that is a government of a city, county, town, 
school district, or special district with a population of less than 
50,000; or (3) a small organization that is any not-for-profit 
enterprise which is independently owned and operated and is not 
dominant in its field.
    After considering the economic impact of today's proposed rule on 
small entities, I certify that this action will not have a significant 
impact on a substantial number of small entities. In accordance with 
the RFA, we conducted an assessment of the proposed standards on small 
businesses within the chlorine manufacturing industry. Based on 
definition of a small entity explained above, we identified three of 
the eight companies that own mercury cell chlor-alkali plants as small. 
Although small businesses represent 30 percent of the companies within 
the source category, they are expected to incur only 18 percent of the 
total industry annual compliance costs. There are no companies with 
compliance costs equal to or greater than 1 percent of their sales. No 
firms are expected to close rather than incur the costs of compliance 
with the proposed rule. Furthermore, firms are not projected to shut 
down their facilities due to the proposed rule.
    Although the proposed rule will not have a significant economic 
impact on a substantial number of small entities, we have nonetheless 
worked aggressively to minimize the impact of the proposed rule on 
small entities, consistent with our obligation under the CAA.
    In summary, this analysis supports today's certification under the 
RFA because no firms experience a significant impact due to the 
proposed rule. For more information, consult the docket for the 
proposed rule.

G. Paperwork Reduction Act

    The information collection requirements in this proposed rule will 
be submitted for approval to OMB under the Paperwork Reduction Act, 44 
U.S.C. 3501 et seq. An information collection request (ICR) document 
has been prepared by the EPA for mercury cell chlor-alkali plants (ICR 
No. 2046.01), and a copy may be obtained from Sandy Farmer by mail at 
the Office of Environmental Information, Collection Strategies Division 
(2822), U.S. EPA, 1200 Pennsylvania Avenue, NW., Washington, DC 20460, 
by email at [email protected], or by calling (202) 260-2740. A copy 
may also be downloaded off the internet at http://www.epa.gov/icr. The 
information requirements are not effective until OMB approves them.
    The information requirements are based on notification, 
recordkeeping, and reporting requirements in the NESHAP General 
Provisions (40 CFR part 63, subpart A), which are mandatory for all 
operators subject to national emission standards. These recordkeeping 
and reporting requirements are specifically authorized by section 114 
of the CAA (42 U.S.C. 7414). All information submitted to the EPA 
pursuant to the recordkeeping and reporting requirements for which a 
claim of confidentiality is made is safeguarded according to Agency 
policies set forth in 40 CFR part 2, subpart B.
    The proposed rule contains monitoring, inspection, recordkeeping, 
and reporting requirements. The monitoring requirements are associated 
with the use of control devices to observe operating limits for by-
product hydrogen streams, end-box ventilation system vents, and mercury 
thermal recovery unit vents. The inspection requirements are associated 
with the observation of work practice standards for cell rooms, 
hydrogen systems, caustic systems, and the storage of mercury-
containing wastes. The recordkeeping and reporting requirements are the 
means of complying with emission limitations and work practice 
standards in the proposed rule.
    The respondent universe consists of twelve existing mercury cell 
chlor-alkali plants in the U.S. which would need to comply with 
requirements within 2 years of the effective date of the subpart. The 
annual respondent monitoring, inspection, recordkeeping, and reporting 
burden for this collection of information (averaged over the first 3 
years after the effective date of the subpart) is estimated to total 
about 14,000 labor hours at a total annual cost of about $630,000. This 
estimate includes rule review and planning; initial notification (one-
time) to the EPA; one-time preparation of a startup, shutdown, and 
malfunction plan with semiannual reports if procedures in the plan were 
followed or immediate reporting if they were not followed; one-time 
preparation of a site-specific monitoring plan addressing performance 
and equipment specifications as well as procedures for performance 
evaluation, ongoing operation and maintenance, ongoing data quality 
assurance, and ongoing recordkeeping and reporting for continuous 
mercury vapor monitors for vents; acquisition and installation of vent 
monitors; performance testing for each vent (one time in the 3 year 
period), including notification of intent to conduct testing and 
establishment of vent mercury concentration operating limits; reporting 
of test results, including one-time preparation of notification of 
compliance status for vents; one-time preparation of a washdown plan; 
one-time preparation of notification of compliance status for work 
practice standards; continuous monitoring of vent outlet elemental 
mercury concentration and recording of data; recording of information 
related to the washdown plan; inspections and keeping records related 
to equipment problems, deficiencies in floors, pillars, and beams, 
caustic leaks, liquid mercury spills and accumulations, liquid mercury 
leaks, and hydrogen/mercury vapor leaks; keeping records related to 
liquid mercury collection; keeping records related to storage of 
mercury-containing wastes; and preparation of semiannual compliance 
reports.
    Burden means the total time, effort, or financial resources 
expended by persons to generate, maintain, retain, or disclose or 
provide information to or for a Federal agency. This includes the time 
needed to review instructions; develop, acquire, install, and utilize 
technology and systems for the purposes of collecting, validating, and 
verifying information, processing and maintaining information, and 
disclosing and providing information; adjust the existing ways to 
comply with any previously applicable instructions and requirements; 
train personnel to be able to respond to a collection of information; 
search data sources; complete and review the collection of information; 
and transmit or otherwise disclose the information.
    An Agency may not conduct or sponsor, and a person is not required 
to respond to, a collection of information unless it displays a 
currently valid OMB control number. The OMB control numbers for our 
rules are listed in 40 CFR part 9 and 48 CFR chapter 15.
    Comments are requested on EPA's need for this information, the 
accuracy of the burden estimates, and any suggested methods for 
minimizing respondent burden, including through the use of automated 
collection techniques. Send comments on the ICR to the Director, 
Collection Strategies

[[Page 44697]]

Division (2822), U.S. EPA (2136), 1200 Pennsylvania Avenue, NW, 
Washington, DC 20460; and to the Office of Information and Regulatory 
Affairs, Office of Management and Budget, 725 17th Street, NW, 
Washington, DC 20503, marked ``Attention: Desk Office for EPA.'' 
Include the ICR number in any correspondence. Because OMB is required 
to make a decision concerning the ICR between 30 and 60 days after July 
3, 2002, a comment to OMB is best assured of having its full effect if 
OMB receives it by August 2, 2002. The final rule will respond to any 
OMB or public comments on the information collection requirements 
contained in the proposed rule.

H. National Technology Transfer and Advancement Act

    Section 12(d) of the National Technology Transfer and Advancement 
Act (NTTAA) of 1995 (Public Law No. 104-113; 15 U.S.C. 272 note) 
directs the EPA to use voluntary consensus standards in their 
regulatory and procurement activities unless to do so would be 
inconsistent with applicable law or otherwise impractical. Voluntary 
consensus standards are technical standards (e.g., materials 
specifications, test methods, sampling procedures, business practices) 
developed or adopted by one or more voluntary consensus bodies. The 
NTTAA directs the EPA to provide Congress, through annual reports to 
OMB, with explanations when an agency does not use available and 
applicable voluntary consensus standards.
    The proposed rule involve technical standards. The EPA proposes in 
the proposed rule to use EPA Methods 1, 1A, 2, 2A, 2C, 2D, 3, 3A, 3B, 
4, 5, 101, 101A, and 102. Consistent with the NTTAA, the EPA conducted 
searches to identify voluntary consensus standards in addition to these 
EPA methods. No applicable voluntary consensus standards were 
identified for EPA Methods 1A, 2A, 2D, and 102. The search and review 
results have been documented and are placed in the docket (No. A-2000-
32) for the proposed rule.
    This search for emissions monitoring procedures identified 14 
voluntary consensus standards and 5 draft standards. The EPA determined 
that the 14 standards were impractical alternatives to EPA test methods 
for the purposes of the proposed rule. Therefore, the EPA does not 
propose to adopt these 14 voluntary consensus standards in the proposed 
rule. The detailed EPA review comments for these 14 standards are in 
the docket for the proposed rule (Please see docket No. A-2000-32).
    The 14 voluntary consensus standards are as follows: ASME C00031 or 
PTC 19-10-1981, ``Part 10 Flue and Exhaust Gas Analyses,'' for EPA 
Method 3; ASME PTC-38-80 R85 or C00049, ``Determination of the 
Concentration of Particulate Matter in Gas Streams,'' for EPA Method 5; 
ASTM D3154-91 (1995), ``Standard Method for Average Velocity in a Duct 
(Pitot Tube Method),'' for EPA Methods 1, 2, 2C, 3, 3B, and 4; ASTM 
D3464-96, ``Standard Test Method Average Velocity in a Duct Using a 
Thermal Anemometer,'' for EPA Method 2; ASTM D3685/D3685M-98, ``Test 
Methods for Sampling and Determination of Particulate Matter in Stack 
Gases,'' for EPA Method 5; ASTM D3796-90 (1998), ``Standard Practice 
for Calibration of Type S Pitot Tubes,'' for EPA Method 2; ASTM D5835-
95, ``Standard Practice for Sampling Stationary Source Emissions for 
Automated Determination of Gas Concentration,'' for EPA Methods 3A; 
ASTM E337-84 (Reapproved 1996), ``Standard Test Method for Measuring 
Humidity with a Psychrometer (the Measurement of Wet- and Dry-Bulb 
Temperatures),'' for EPA Method 4; CAN/CSA Z223.1-M1977, ``Method for 
the Determination of Particulate Mass Flows in Enclosed Gas Streams,'' 
for EPA Method 5; CAN/CSA Z223.2-M86 (1986), ``Method for the 
Continuous Measurement of Oxygen, Carbon Dioxide, Carbon Monoxide, 
Sulphur Dioxide, and Oxides of Nitrogen in Enclosed Combustion Flue Gas 
Streams,'' for EPA Methods 3A; CAN/CSA Z223.26-M1987, ``Measurement of 
Total Mercury in Air Cold Vapour Atomic Absorption Spectrophotometeric 
Method,'' for EPA Methods 101 and 101A; ISO 9096:1992 (in review 2000), 
``Determination of Concentration and Mass Flow Rate of Particulate 
Matter in Gas Carrying Ducts--Manual Gravimetric Method,'' for EPA 
Method 5; ISO 10396:1993, ``Stationary Source Emissions: Sampling for 
the Automated Determination of Gas Concentrations,'' for EPA Method 3A; 
ISO 10780:1994, ``Stationary Source Emissions--Measurement of Velocity 
and Volume Flowrate of Gas Streams in Ducts,'' for EPA Method 2.
    Five of the standards identified in this search were not available 
at the time the review was conducted for the purposes of the proposed 
rule because they are under development by a voluntary consensus body: 
ASME/BSR MFC 12M, ``Flow in Closed Conduits Using Multiport Averaging 
Pitot Primary Flowmeters,'' for EPA Method 2; ASME/BSR MFC 13M, ``Flow 
Measurement by Velocity Traverse,'' for EPA Method 2 (and possibly 1); 
ISO/DIS 12039, ``Stationary Source Emissions--Determination of Carbon 
Monoxide, Carbon Dioxide, and Oxygen--Automated Methods,'' for EPA 
Method 3A; PREN 13211 (1998), ``Air Quality--Stationary Source 
Emissions--Determination of the Concentration of Total Mercury,'' for 
EPA Methods 101, 101A (and mercury portion of EPA Method 29); and ASTM 
Z6590Z, ``Manual Method for Both Speciated and Elemental Mercury'' is a 
potential alternative for portions of EPA Methods 101A and Method 29 
(mercury portion only).
    We are not proposing to include these five draft voluntary 
consensus standards in the proposed rule. The EPA, however, will review 
the standards when they are final. The review comments for these five 
standards are in the same docket entry as cited above.
    The EPA takes comment on the compliance demonstration requirements 
in the proposed rule and specifically invites the public to identify 
potentially-applicable voluntary consensus standards. Commenters should 
also explain why the proposed rule should adopt these voluntary 
consensus standards in lieu of or in addition to EPA's standards. 
Emission test methods submitted for evaluation should be accompanied 
with a basis for the recommendation, including method validation data 
and the procedure used to validate the candidate method (if a method 
other than Method 301, 40 CFR part 63, appendix A was used).
    Section 63.8232 of the proposed standards lists the EPA testing 
methods included in the proposed rule. Under Sec. 63.8 of the NESHAP 
General Provisions, a source may apply to the EPA for permission to use 
alternative monitoring in place of any of the EPA testing methods.

I. Executive Order 13211, Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use

    The proposed rule is not subject to Executive Order 13211 (66 FR 
28355, May 22, 2001) because it is not a significant regulatory action 
under Executive Order 12866.

List of Subjects in 40 CFR Part 63

    Environmental protection, Air emissions control, Hazardous air 
pollutants, Reporting and recordkeeping requirements.


[[Page 44698]]


    Dated: June 17, 2002.
Christine Todd Whitman,
Administrator.
    For the reasons stated in the preamble, title 40, chapter I, part 
63 of the Code of the Federal Regulations is proposed to be amended as 
follows:

PART 63--[AMENDED]

    1. The authority citation for part 63 continues to read as follows:

    Authority: 42 U.S.C. 7401, et seq.
    2. Part 63 amended by adding Subpart IIIII to read as follows:

Subpart IIIII--National Emission Standards for Hazardous Air 
Pollutants for Mercury Cell Chlor-Alkali Plants

Sec.

What This Subpart Covers

63.8180  What is the purpose of this subpart?
63.8182  Am I subject to this subpart?
63.8184  What parts of my plant does this subpart cover?
63.8186  When do I have to comply with this subpart?

Emission Limitations and Work Practice Standards

63.8190  What emission limitations must I meet?
63.8192   What work practice standards must I meet?

Operation and Maintenance Requirements

63.8222  What are my operation and maintenance requirements?

General Compliance Requirements

63.8226  What are my general requirements for complying with this 
subpart?

Initial Compliance Requirements

63.8230  By what date must I conduct performance tests or other 
initial compliance demonstrations?
63.8231  When must I conduct subsequent performance tests?
63.8232  What test methods and other procedures must I use to 
demonstrate initial compliance with the emission limits?
63.8234  What equations and procedures must I use?
63.8236  How do I demonstrate initial compliance with the emission 
limitations and work practice standards?

Continuous Compliance Requirements

63.8240  What are my monitoring requirements?
63.8242  What are the installation, operation, and maintenance 
requirements for my mercury concentration continuous monitoring 
systems?
63.8244  How do I monitor and collect data to demonstrate continuous 
compliance?
63.8246  How do I demonstrate continuous compliance with the 
emission limitations and work practice standards?
63.8248  What other requirements must I meet to demonstrate 
continuous compliance?

Notifications, Reports, and Records

63.8252  What notifications must I submit and when?
63.8254  What reports must I submit and when?
63.8256  What records must I keep?
63.8258  In what form and how long must I keep my records?

Other Requirements and Information

63.8262  What parts of the General Provisions apply to me?
63.8264  Who implements and enforces this subpart?
63.8266  What definitions apply to this subpart?

Tables to Subpart IIIII of Part 63

Table 1 to Subpart IIIII of Part 63--Work Practice Standards--
Design, Operation, and Maintenance Requirements
Table 2 to Subpart IIIII of Part 63--Work Practice Standards--
Required Inspections
Table 3 to Subpart IIIII of Part 63--Work Practice Standards--
Required Actions for Liquid Mercury Spills and Accumulations and 
Hydrogen and Mercury Vapor Leaks
Table 4 to Subpart IIIII of Part 63--Work Practice Standards--
Requirements for Mercury Liquid Collection
Table 5 to Subpart IIIII of Part 63--Work Practice Standards--
Requirements for Handling and Storage of Mercury-Containing Wastes
Table 6 to Subpart IIIII of Part 63--Required Elements of Washdown 
Plans
Table 7 to Subpart IIIII of Part 63--Examples of Techniques for 
Equipment Problem Identification, Leak Detection and Mercury Vapor 
Measurements
Table 8 to Subpart IIIII of Part 63--Required Records for Work 
Practice Standards
Table 9 to Subpart IIIII of Part 63--Applicability of General 
Provisions to Subpart IIIII

Subpart IIIII--National Emission Standards for Hazardous Air 
Pollutants for Mercury Cell Chlor-Alkali Plants

What This Subpart Covers


Sec. 63.8180  What is the purpose of this subpart?

    This subpart establishes national emission standards for hazardous 
air pollutants (NESHAP) for sources of mercury emissions at mercury 
cell chlor-alkali plants. This subpart also establishes requirements to 
demonstrate initial and continuous compliance with all applicable 
emission limitations and work practice standards in this subpart.


Sec. 63.8182  Am I subject to this subpart?

    (a) You are subject to this subpart if you own or operate a mercury 
cell chlor-alkali plant.
    (b) You are required to obtain a title V permit for each source 
subject to this subpart, whether your source is (or is part of) a major 
source of hazardous air pollutant (HAP) emissions or an area source of 
HAP emissions. A major source of HAP is a plant site that emits or has 
the potential to emit any single HAP at a rate of 10 tons or more per 
year or any combination of HAP at a rate of 25 tons or more per year. 
An area source of HAP is a plant site that has the potential to emit 
HAP but is not a major source.
    (c) Beginning on [DATE 2 YEARS FROM THE DATE OF PUBLICATION OF THE 
FINAL RULE IN THE Federal Register], the provisions of subpart E of 40 
CFR part 61 that apply to mercury chlor-alkali plants, which are listed 
in paragraphs (c)(1) through (3) of this section, are no longer 
applicable.
    (1) 40 CFR 61.52(a).
    (2) 40 CFR 61.53 (b) and (c).
    (3) 40 CFR 61.55 (b), (c) and (d).


Sec. 63.8184  What parts of my plant does this subpart cover?

    (a) This subpart applies to each affected source at a plant site 
where chlorine and caustic are produced in mercury cells. This subpart 
applies to two types of affected sources: the mercury cell chlor-alkali 
production facility, as defined in paragraph (a)(1) of this section; 
and the mercury recovery facility, as defined in paragraph (a)(2) of 
this section.
    (1) The mercury cell chlor-alkali production facility designates an 
affected source consisting of all cell rooms and ancillary operations 
used in the manufacture of product chlorine, product caustic, and by-
product hydrogen at a plant site. This subpart covers mercury emissions 
from by-product hydrogen streams, end-box ventilation system vents, and 
fugitive emission sources associated with cell rooms, hydrogen systems, 
caustic systems, and storage areas for mercury-containing wastes.
    (2) The mercury recovery facility designates an affected source 
consisting of all processes and associated operations needed for 
mercury recovery from wastes at a plant site. This subpart covers 
mercury emissions from mercury thermal recovery unit vents and fugitive 
emission sources associated with storage areas for mercury-containing 
wastes.
    (b) An affected source at your mercury cell chlor-alkali plant is 
existing if you commenced construction of the affected source before 
July 3, 2002.
    (c) A mercury recovery facility is a new affected source if you 
commence construction or reconstruction of the affected source after 
July 3, 2002. An affected source is reconstructed if it

[[Page 44699]]

meets the definition of ``reconstruction'' in Sec. 63.2.


Sec. 63.8186  When do I have to comply with this subpart?

    (a) If you have an existing affected source, you must comply with 
each emission limitation, work practice standard, and recordkeeping and 
reporting requirement in this subpart that applies to you no later than 
[DATE 2 YEARS FROM THE DATE OF PUBLICATION OF THE FINAL RULE IN THE 
Federal Register].
    (b) If you have a new or reconstructed mercury recovery facility 
and its initial startup date is on or before [DATE OF PUBLICATION OF 
THE FINAL RULE IN THE Federal Register], you must comply with each 
emission limitation, work practice standard, and recordkeeping and 
reporting requirement in this subpart that applies to you by [DATE OF 
PUBLICATION OF THE FINAL RULE IN THE FEDERAL REGISTER].
    (c) If you have a new or reconstructed mercury recovery facility 
and its initial startup date is after [DATE OF PUBLICATION OF THE FINAL 
RULE IN THE FEDERAL REGISTER], you must comply with each emission 
limitation, work practice standard, and recordkeeping and reporting 
requirement in this subpart that applies to you upon initial startup.
    (d) You must meet the notification and schedule requirements in 
Sec. 63.8252. Several of these notifications must be submitted before 
the compliance date for your affected source(s).

Emission Limitations and Work Practice Standards


Sec. 63.8190  What emission limitations must I meet?

    (a) Emission limits. You must meet each emission limit in 
paragraphs (a)(1) through (3) of this section that applies to you.
    (1) New or reconstructed mercury cell chlor-alkali production 
facility. Emissions of mercury are prohibited from a new or 
reconstructed mercury cell chlor-alkali production facility.
    (2) Existing mercury cell chlor-alkali production facility. You 
must not discharge to the atmosphere aggregate mercury emissions in 
excess of the applicable limit in paragraph (a)(2)(i) or (ii) of this 
section.
    (i) 0.067 grams of mercury per megagram of chlorine produced (1.3 x 
10-4 pounds of mercury per ton of chlorine produced) from 
all by-product hydrogen streams and all end-box ventilation system 
vents when both types of emission points are present.
    (ii) 0.033 grams of mercury per megagram of chlorine produced (6.59 
x 10-5 pounds of mercury per ton of chlorine produced) from 
all by-product hydrogen streams when there are no end-box ventilation 
systems.
    (3) New, reconstructed, or existing mercury recovery facility. You 
must not discharge to the atmosphere mercury emissions in excess of the 
applicable limit in paragraph (a)(3)(i) or (ii) of this section.
    (i) 23 milligrams per dry standard cubic meter from each oven type 
mercury thermal recovery unit vent.
    (ii) 4 milligrams per dry standard cubic meter from each non-oven 
type mercury thermal recovery unit vent.
    (b) Operating limits. You must meet each operating limit in 
paragraphs (b)(1) and (2) of this section that applies to you.
    (1) Existing mercury cell chlor-alkali production facility. You 
must maintain the daily average mercury concentration in each by-
product hydrogen stream no higher than the level established during the 
initial performance test. You must maintain the daily average mercury 
concentration in each end-box ventilation system vent exhaust no higher 
than the level established during the initial performance test.
    (2) New, reconstructed, or existing mercury recovery facility. You 
must maintain the daily average mercury concentration in each oven type 
mercury thermal recovery unit vent exhaust no higher than the level 
established during the initial performance test. You must maintain the 
daily average mercury concentration in each non-oven type mercury 
thermal recovery unit vent exhaust no higher than the level established 
during the initial performance test.


Sec. 63.8192  What work practice standards must I meet?

    (a) You must meet the work practice standards in Tables 1 through 5 
to this subpart.
    (b) You must adhere to the response intervals specified in Tables 1 
through 5 to this subpart at all times. Nonadherence to the intervals 
in Tables 1 through 5 to this subpart constitutes a deviation and must 
be documented and reported in the compliance report, as required by 
Sec. 63.8254(c), with the date and time of the deviation, cause of the 
deviation, a description of the conditions, and time actual compliance 
was achieved.
    (c) As provided in Sec. 63.6(g), you may request to use an 
alternative to the work practice standards in Tables 1 through 5 to 
this subpart.
    (d) You must prepare, submit, and operate according to a written 
washdown plan designed to minimize fugitive mercury emissions through 
routine washing of surfaces where liquid mercury could accumulate. The 
written plan must address the elements contained in Table to this 
subpart.
    (e) You must institute a cell room monitoring program to 
continuously monitor the elemental mercury vapor concentration in the 
upper portion of each cell room against a predetermined site-specific 
action level(s). When a mercury concentration is detected that exceeds 
the established action level(s), you must identify the cause of the 
elevated concentration and take corrective action as quickly as 
possible. At a minimum, these follow-up activities should include the 
relevant work practices in Tables 1 through 5 to this subpart. You must 
also keep records related to the inspections and corrective actions 
performed.

Operation and Maintenance Requirements


Sec. 63.8222  What are my operation and maintenance requirements?

    As required by Sec. 63.6(e)(1)(i), you must always operate and 
maintain your affected source(s), including air pollution control and 
monitoring equipment, in a manner consistent with good air pollution 
control practices for minimizing emissions at least to the levels 
required by this subpart.

General Compliance Requirements


Sec. 63.8226  What are my general requirements for complying with this 
subpart?

    (a) You must be in compliance with the emission limitations 
(including operating limits) for by-product hydrogen streams, end-box 
ventilation system vents, and mercury thermal recovery unit vents in 
Sec. 63.8190 at all times, except during periods of startup, shutdown, 
and malfunction. You must be in compliance with the applicable work 
practice standards in Sec. 63.8192 at all times, except during periods 
of startup, shutdown, and malfunction.
    (b) During the period between the compliance date specified for 
your affected source in Sec. 63.8186 and the date upon which mercury 
concentration continuous monitoring systems (CMS) have been installed 
and certified and any applicable operating limits have been set, you 
must maintain a log detailing the operation and maintenance of the 
process and emissions control equipment.
    (c) You must develop and implement a written startup, shutdown, and

[[Page 44700]]

malfunction plan (SSMP) according to the provisions in Sec. 63.6(e)(3).

Initial Compliance Requirements


Sec. 63.8230  By what date must I conduct performance tests or other 
initial compliance demonstrations?

    (a) As required in Sec. 63.7(a)(2), you must conduct a performance 
test within 180 calendar days of the compliance date that is specified 
in Sec. 63.8186 for your affected source to demonstrate initial 
compliance with the emission limits in Sec. 63.8190(a)(2) for by-
product hydrogen streams and end-box ventilation system vents and the 
emission limits in Sec. 63.8190(a)(3) for mercury thermal recovery unit 
vents.
    (b) For each work practice standard in Sec. 63.8192 where initial 
compliance is not demonstrated using a performance test, you must 
demonstrate initial compliance within 30 calendar days after the 
compliance date that is specified for your affected source in 
Sec. 63.8186.
    (c) If you commenced construction or reconstruction of a mercury 
recovery facility between July 3, 2002 and [DATE OF PUBLICATION OF THE 
FINAL RULE IN THE Federal Register, you must demonstrate initial 
compliance with either the proposed emission limit or the promulgated 
emission limit no later than [DATE 180 DAYS AFTER THE DATE OF 
PUBLICATION OF THE FINAL RULE IN THE Federal Register] or no later than 
180 days after startup of the source, whichever is later, according to 
Sec. 63.7(a)(2)(ix).
    (d) If you commenced construction or reconstruction of a mercury 
recovery facility between July 3, 2002 and [INSERT DATE OF PUBLICATION 
OF THE FINAL RULE IN THE Federal Register], and you chose to comply 
with the proposed emission limit when demonstrating initial compliance, 
you must conduct a second performance test to demonstrate compliance 
with the promulgated emission limit by [DATE 3 YEARS AND 180 DAYS AFTER 
THE DATE OF PUBLICATION OF THE FINAL RULE IN THE Federal Register], or 
after startup of the source, whichever is later, according to 
Sec. 63.7(a)(2)(ix).


Sec. 63.8231  When must I conduct subsequent performance tests?

    You must conduct subsequent performance tests to demonstrate 
compliance with the emission limits in Sec. 63.8190(a)(2) for by-
product hydrogen streams and end-box ventilation system vents and the 
emission limits in Sec. 63.8190(a)(3) for mercury thermal recovery unit 
vents no less frequently than twice (at mid-term and renewal) during 
each term of each title V permit.


Sec. 63.8232  What test methods and other procedures must I use to 
demonstrate initial compliance with the emission limits?

    You must conduct a performance test for each by-product hydrogen 
stream, end-box ventilation system vent, and mercury thermal recovery 
unit vent according to the requirements in Sec. 63.7(e)(1) and the 
conditions detailed in paragraphs (a) through (f) of this section.
    (a) You may not conduct performance tests during periods of 
startup, shutdown, or malfunction, as specified in Sec. 63.7(e)(1).
    (b) For each performance test, you must develop a site-specific 
test plan in accordance with Sec. 63.7(c)(2).
    (c) You must conduct at least three valid test runs in order to 
comprise a performance test, as specified in Sec. 63.7(e)(3). To be 
considered a valid test run, the sampling time must be at least 2 hours 
and the mercury concentration in the field sample must be at least 2 
times the limit of detection for the analytical method.
    (d) You must use the test methods specified in paragraphs (d)(1) 
through (4) of this section and the applicable test methods in 
paragraphs (d)(5) through (7) of this section.
    (1) Method 1 or 1A in appendix A of 40 CFR part 60 to determine the 
sampling port locations and the location and required number of 
sampling traverse points.
    (2) Method 2, 2A, 2C, or 2D in appendix A of 40 CFR part 60 to 
determine the stack gas velocity and volumetric flow rate.
    (3) Method 3, 3A, or 3B in appendix A of 40 CFR part 60 to 
determine the stack gas molecular weight.
    (4) Method 4 in appendix A of 40 CFR part 60 to determine the stack 
gas moisture content.
    (5) For each by-product hydrogen stream, Method 102 in appendix A 
of 40 CFR part 61 to measure the mercury emission rate after the last 
control device.
    (6) For each end-box ventilation system vent, Method 101 or 101A in 
appendix A of 40 CFR part 61 to measure the mercury emission rate after 
the last control device.
    (7) For each mercury thermal recovery unit vent, Method 101 or 101A 
in appendix A of 40 CFR part 61 to measure the mercury emission rate 
after the last control device.
    (e) During each test run for a by-product hydrogen stream and each 
test run for an end-box ventilation system vent, you must continuously 
measure the electric current through the operating mercury cells and 
record a measurement at least once every 15 minutes.
    (f) During each test run for a mercury thermal recovery unit vent, 
the mercury-containing waste processed in the retort must be the type 
of waste that results in the highest mercury concentration in the 
mercury thermal recovery unit vent. You must document the mercury 
content of this type of waste and an explanation of why it results in 
the highest mercury concentration in the site-specific test plan 
required in Sec. 63.8232(b).


Sec. 63.8234  What equations and procedures must I use?

    (a) To determine the grams of mercury discharged per megagram 
(grams Hg/Mg Cl2) of chlorine produced from all by-product 
hydrogen streams and all end-box ventilation system vents, if 
applicable, at a mercury cell chlor-alkali production facility, you 
must follow the procedures in paragraphs (a)(1) through (6) of this 
section.
    (1) Determine the mercury emission rate for each test run, 
Rrun, in grams per day for each by-product hydrogen stream 
and for each end-box ventilation system vent, if applicable, from 
Method 101, 101A, or 102 (40 CFR part 61).
    (2) Calculate the average measured electric current through the 
operating mercury cells during each test run for each by-product 
hydrogen stream and for each end-box ventilation system vent, if 
applicable, using Equation 1 of this section as follows:
[GRAPHIC] [TIFF OMITTED] TP03JY02.000


Where:

CLavg,run = Average measured cell line current load during 
the test run, amperes;
CLi,run = Individual cell line current load measurement 
(i.e., 15 minute reading) during the test run, amperes; and
n = Number of cell line current load measurements taken over the 
duration of the test run.

    (3) Calculate the amount of chlorine produced during each test run 
for each by-product hydrogen stream and for each end-box ventilation 
system vent, if applicable, using Equation 2 of this section as 
follows:

[[Page 44701]]

[GRAPHIC] [TIFF OMITTED] TP03JY02.001


Where:

PCl2, run = Amount of chlorine produced during the test run, 
megagrams chlorine (Mg Cl2) ;
1.3x10-6 = Theoretical chlorine production rate factor, Mg 
Cl2 per hour per ampere per cell;
CLavg, run = Average measured cell line current load during 
test run, amperes, calculated using Equation 1 of this section;
ncell, run = Number of cells on-line during the test run; 
and
trun = Duration of test run, hours.
    (4) Calculate the mercury emission rate in grams of mercury per 
megagram of chlorine produced for each test run for each by-product 
hydrogen stream and for each end-box ventilation system vent, if 
applicable, using Equation 3 of this section as follows:
[GRAPHIC] [TIFF OMITTED] TP03JY02.002


Where:

EHg, run = Mercury emission rate for the test run, grams Hg/
Mg Cl2;
Rrun = Measured mercury emission rate for the test run from 
paragraph (a)(1) of this section, grams Hg per day;
trun = Duration of test run, hours;
24 = Conversion factor, hours per day; and
PCl2, run = Amount of chlorine produced during the test run, 
calculated using Equation 2 of this section, Mg Cl2.

    (5) Calculate the average mercury emission rate for each by-product 
hydrogen stream and for each end-box ventilation system vent, if 
applicable, using Equation 4 of this section as follows:
[GRAPHIC] [TIFF OMITTED] TP03JY02.003


Where:

EHg,avg = Average mercury emission rate for the by-product 
hydrogen stream or the end-box ventilation system vent, if applicable, 
grams HMg Cl2;
EHg,run = Mercury emission rate for each test run for the 
by-product hydrogen stream or the end-box ventilation system vent, if 
applicable, grams Hg/Mg Cl2, calculated using Equation 3 of 
this section; and
n = Number of test runs conducted for the by-product hydrogen stream or 
the end-box ventilation system vent, if applicable.

    (6) Calculate the total mercury emission rate from all by-product 
hydrogen streams and all end-box ventilation system vents, if 
applicable, at the mercury cell chlor-alkali production facility using 
Equation 5 of this section as follows:
[GRAPHIC] [TIFF OMITTED] TP03JY02.004


Where:

EHg,H2EB = Total mercury emission rate from all by-product 
hydrogen streams and all end-box ventilation system vents, if 
applicable, at the affected source, grams Hg/Mg Cl2;
EHg,avg = Average mercury emission rate for each by-product 
hydrogen stream and each end-box ventilation system vent, if 
applicable, grams Hg/Mg Cl2, determined using Equation 4 of 
this section; and
n = total number of by-product hydrogen streams and end-box ventilation 
system vents at the affected source.

    (b) To determine the milligrams of mercury per dry standard cubic 
meter exhaust discharged from mercury thermal recovery unit vents, you 
must follow the procedures in paragraphs (b)(1) and (2) of this 
section.
    (1) Calculate the concentration of mercury in milligrams of mercury 
per dry standard cubic meter of exhaust for each test run for each 
mercury thermal recovery unit vent using Equation 6 of this section as 
follows:
[GRAPHIC] [TIFF OMITTED] TP03JY02.005

    Where:

CHg, run = Mercury concentration for the test run, 
milligrams of mercury per dry standard cubic meter of exhaust;
mHg = Mass of mercury in test run sample, from Method 101, 
101A, or 102, micrograms;
    10-3 = Conversion factor, milligrams per microgram; and
Vm(std) = Dry gas sample volume at standard conditions, from 
Method 101, 101A, or 102, dry standard cubic meters.

    (2) Calculate the average concentration of mercury in each mercury 
thermal recovery unit vent exhaust using Equation 7 of this section as 
follows:
[GRAPHIC] [TIFF OMITTED] TP03JY02.006


Where:

CHg,avg = Average mercury concentration for the mercury 
thermal recovery unit vent, milligrams of mercury per dry standard 
cubic meter exhaust;
CHg,run = Mercury concentration for each test run, 
milligrams of mercury per dry standard cubic meter of exhaust, 
calculated using Equation 6 of this section; and
n = Number of test runs conducted for the mercury thermal recovery unit 
vent.

    (c) For each by-product hydrogen stream, each end-box ventilation 
system vent, and each mercury thermal recovery unit vent, you must 
establish a site-specific mercury concentration operating limit 
according to the procedures in paragraphs (c)(1) and (2) of this 
section.
    (1) Using a mercury concentration CMS required in Sec. 63.8240, 
measure and record the elemental mercury concentration after the last 
control device at least once every 15 minutes for the entire duration 
of each performance test run.
    (2) Calculate the mercury concentration operating limit based on 
the mercury concentration monitoring data obtained during each valid 
test run of the performance test during which the mercury emissions did 
not exceed the applicable mercury emission limit in Sec. 63.8190(a)(2) 
through (3) using Equation 8 of this section as follows:
[GRAPHIC] [TIFF OMITTED] TP03JY02.007


Where:

OLHgconc = Mercury concentration operating limit, ppmv or 
concentration units selected by the owner/operator;
CHg,i = Concentration of elemental mercury measured at the 
interval i (i.e., 15 minute reading) during each valid test run of the 
performance test during which the mercury emissions did not exceed the 
applicable mercury emission

[[Page 44702]]

limit in Sec. 63.8190(a)(2) through (3) using a mercury concentration 
CMS, ppmv or concentration units selected by the owner/operator; and
n = Number of concentration measurements taken during all test runs of 
the performance test.

    (d) You may change a mercury concentration operating limit by 
following the requirements in paragraphs (d)(1) through (3) of this 
section.
    (1) Submit a written notification to the Administrator of your 
intent to conduct a new performance test to revise the mercury 
concentration operating limit at least 60 calendar days before the test 
is scheduled to begin.
    (2) Conduct a performance test and demonstrate compliance with the 
applicable emission limit.
    (3) Establish a revised mercury concentration operating limit 
according to the procedures in paragraph (c) of this section.
    (e) You must calculate the daily average elemental mercury 
concentration using Equation 9 of this section as follows:
[GRAPHIC] [TIFF OMITTED] TP03JY02.008


Where:

CHg,dailyavg = Average elemental mercury concentration for 
the operating day, ppmv or concentration units selected by the owner/
operator;
CHg,i = Concentration of elemental mercury measured at the 
interval i (i.e., 15 minute reading) using a mercury concentration CMS, 
ppmv or concentration units selected by the owner/operator; and
n = Number of concentration measurements taken during the operating 
day.


Sec. 63.8236  How do I demonstrate initial compliance with the emission 
limitations and work practice standards?

    (a) For each mercury cell chlor-alkali production facility, you 
have demonstrated initial compliance with the emission limits for by-
product hydrogen streams and end-box ventilation system vents in 
Sec. 63.8190(a)(2) if:
    (1) Total mercury emission rate from all by-product hydrogen 
streams and all end-box ventilation system vents, if applicable, at the 
affected source, determined in accordance with Secs. 63.8232 and 
63.8234(a), did not exceed the applicable emission limit in 
Sec. 63.8190(a)(2)(i) or (ii); and
    (2) You have established a mercury concentration operating limit 
for each by-product hydrogen stream and each end-box ventilation system 
vent, if applicable, in accordance with Sec. 63.8234(c), and have a 
record of all mercury concentration monitoring data used to establish 
the limit.
    (b) For each mercury recovery facility, you have demonstrated 
initial compliance with the emission limits for mercury thermal 
recovery unit vents in Sec. 63.8190(a)(3) if:
    (1) Mercury concentration in each mercury thermal recovery unit 
vent exhaust, determined in accordance with Secs. 63.8232 and 
63.8234(b), did not exceed the applicable emission limit in 
Sec. 63.8190(a)(3)(i) or (ii); and
    (2) You have established a mercury concentration operating limit 
for each mercury thermal recovery unit vent in accordance with 
Sec. 63.8234(c) and have a record of all mercury concentration 
monitoring data used to establish the limit.
    (c) For each affected source, you have demonstrated initial 
compliance with the work practice standards in Sec. 63.8192 if you 
certify in your Notification of Compliance Status that you meet or will 
meet each of the work practice standards, if you prepare the washdown 
plan and mercury vapor measurement plan and submit them as part of your 
Notification of Compliance Status, and if you certify in the 
notification that you operate according to or will operate according to 
the plan.
    (d) You must submit the Notification of Compliance Status 
containing the results of the initial compliance demonstration 
according to the requirements in Sec. 63.8252(e).

Continuous Compliance Requirements


Sec. 63.8240  What are my monitoring requirements?

    For each by-product hydrogen stream, each end-box ventilation 
system vent, and each mercury thermal recovery unit vent, you must 
continuously monitor the elemental mercury concentration using a 
mercury concentration CMS monitor according to the requirements in 
Sec. 63.8242.


Sec. 63.8242  What are the installation, operation, and maintenance 
requirements for my mercury concentration continuous monitoring 
systems?

    You must install, operate, and maintain each mercury concentration 
CMS according to paragraphs (a) through (e) of this section.
    (a) Each mercury concentration CMS must sample, analyze, and record 
the concentration of elemental mercury at least once every 15 minutes.
    (b) Each mercury concentration CMS analyzer must have a detector 
with the capability to detect an elemental mercury concentration at or 
below 0.5 times the mercury concentration operating limit established 
in Sec. 63.8234(c).
    (c) In lieu of a promulgated performance specification as required 
in Sec. 63.8(a)(2), you must develop a site-specific monitoring plan 
that addresses the elements in paragraphs (c)(1) through (6) of this 
section.
    (1) Installation and measurement location downstream of the last 
control device for each by-product hydrogen stream, end-box ventilation 
system vent, and mercury thermal recovery unit vent.
    (2) Performance and equipment specifications for the sample 
interface, the pollutant concentration analyzer, and the data 
collection and reduction system.
    (3) Performance evaluation procedures and acceptance criteria 
(i.e., calibrations).
    (4) Ongoing operation and maintenance procedures in accordance with 
the requirements of Sec. 63.8(c)(1), (3), and (4)(ii).
    (5) Ongoing data quality assurance procedures in accordance with 
the requirements of Sec. 63.8(d).
    (6) Ongoing recordkeeping and reporting procedures in accordance 
the general requirements of Sec. 63.10(c), (e)(1), and (e)(2)(i).
    (d) You must conduct a performance evaluation of each mercury 
concentration CMS in accordance with your site-specific monitoring 
plan.
    (e) You must operate and maintain each mercury concentration CMS in 
continuous operation according to the site-specific monitoring plan.


Sec. 63.8244  How do I monitor and collect data to demonstrate 
continuous compliance?

    (a) Except for monitor malfunctions, associated repairs, and 
required quality assurance or control activities (including, as 
applicable, calibration checks and required zero and span adjustments), 
you must monitor elemental mercury concentration continuously (or 
collect data at all required intervals) at all times that the affected 
source is operating.
    (b) You may not use data recorded during monitoring malfunctions, 
associated repairs, and required quality assurance or control 
activities in data averages and calculations used to report emission or 
operating levels or to fulfill a minimum data availability requirement, 
if applicable. You must use all the data collected during all other 
periods in assessing compliance.
    (c) A monitoring malfunction is any sudden, infrequent, not 
reasonably

[[Page 44703]]

preventable failure of the monitoring to provide valid data. Monitoring 
failures that are caused in part by poor maintenance or careless 
operation are not malfunctions.


Sec. 63.8246  How do I demonstrate continuous compliance with the 
emission limitations and work practice standards?

    (a) For each by-product hydrogen stream, each end-box ventilation 
system vent, and each mercury thermal recovery unit vent, you must 
demonstrate continuous compliance with each mercury concentration 
operating limit by:
    (1) Collecting mercury concentration data according to 
Sec. 63.8244(a), representing at least 90 percent of the 15 minute 
periods in the operating day (with data recorded during monitoring 
malfunctions, associated repairs, and required quality assurance or 
control activities not counting toward the 90 percent requirement);
    (2) Reducing the mercury concentration data to daily averages using 
Equation 9 of Sec. 63.8234(e), not including data recorded during 
monitoring malfunctions, associated repairs, and required quality 
assurance or control activities;
    (3) Maintaining the daily average elemental mercury concentration 
no higher than the mercury concentration operating limit established in 
Sec. 63.8234(c); and
    (4) Maintaining records of mercury concentration monitoring and 
daily average values, as required in Sec. 63.8256(b)(3) and (4).
    (b) You must demonstrate continuous compliance with the work 
practice standards in Sec. 63.8192 by maintaining records in accordance 
with Sec. 63.8256(c).


Sec. 63.8248  What other requirements must I meet to demonstrate 
continuous compliance?

    (a) Deviations. You must report each instance in which you did not 
meet each emission limitation in Sec. 63.8190 that applies to you. This 
includes periods of startup, shutdown, and malfunction. You also must 
report each instance in which you did not meet each work practice 
standard in Sec. 63.8192 that applies to you. These instances are 
deviations from the emission limitations and work practice standards in 
this subpart. These deviations must be reported according to the 
requirements in Sec. 63.8254.
    (b) Startups, shutdowns, and malfunctions. During periods of 
startup, shutdown, and malfunction, you must operate in accordance with 
your startup, shutdown, and malfunction plan required in 
Sec. 63.8226(c).
    (1) Consistent with Secs. 63.6(e) and 63.7(e)(1), deviations that 
occur during a period of startup, shutdown, or malfunction are not 
violations if you demonstrate to the Administrator's satisfaction that 
you were operating in accordance with the startup, shutdown, and 
malfunction plan.
    (2) The Administrator will determine whether deviations that occur 
during a period of startup, shutdown, or malfunction are violations, 
according to the provisions in Sec. 63.6(e).

Notification, Reports, and Records


Sec. 63.8252  What notifications must I submit and when?

    (a) You must submit all of the notifications in Secs. 63.7(b) and 
(c), 63.8(e), (f) and 63.9(b) through (h) that apply to you by the 
dates specified.
    (b) As specified in Sec. 63.9(b)(2), if you start up your affected 
source before [DATE OF PUBLICATION OF THE FINAL RULE IN THE Federal 
Register], you must submit your initial notification not later than 
[DATE 120 DAYS AFTER THE DATE OF PUBLICATION OF THE FINAL RULE IN THE 
Federal Register].
    (c) As specified in Sec. 63.9(b)(3), if you start up your new or 
reconstructed mercury recovery facility on or after [DATE OF 
PUBLICATION OF THE FINAL RULE IN THE Federal Register], you must submit 
your initial notification not later than 120 days after you become 
subject to this subpart.
    (d) For each performance test that you are required to conduct for 
by-product hydrogen streams and end-box ventilation system vents and 
for mercury thermal recovery unit vents, you must submit a notification 
of intent to conduct a performance test at least 60 calendar days 
before the performance test is scheduled to begin as required in 
Sec. 63.7(b)(1).
    (e) You must submit a Notification of Compliance Status in 
accordance with paragraphs (e)(1) and (2) of this section.
    (1) For each initial compliance demonstration that does not include 
a performance test, you must submit the Notification of Compliance 
Status before the close of business on the 30th calendar day following 
the completion of the initial compliance demonstration. This 
Notification of Compliance Status must certify that you meet or will 
meet each work practice standard in Sec. 63.8192. The washdown plan 
must also be submitted, and the Notification of Compliance Status must 
certify that you operate according to or will operate according to the 
plan.
    (2) For each initial compliance demonstration that does include a 
performance test, you must submit the Notification of Compliance 
Status, including the performance test results, before the close of 
business on the 60th calendar day following the completion of the 
performance test according to Sec. 63.10(d)(2). The Notification of 
Compliance Status must contain the information in 
Sec. 63.9(h)(2)(ii)(A) through (G). The site-specific monitoring plan 
required in Sec. 63.8242(c) must also be submitted.


Sec. 63.8254  What reports must I submit and when?

    (a) Compliance report due dates. Unless the Administrator has 
approved a different schedule, you must submit a semiannual compliance 
report to your permitting authority according to the requirements in 
paragraphs (a)(1) through (5) of this section.
    (1) The first compliance report must cover the period beginning on 
the compliance date that is specified for your affected source in 
Sec. 63.8186 and ending on June 30 or December 31, whichever date comes 
first after the compliance date that is specified for your affected 
source in Sec. 63.8186.
    (2) The first compliance report must be postmarked or delivered no 
later than July 31 or January 31, whichever date comes first after your 
first compliance report is due.
    (3) Each subsequent compliance report must cover the semiannual 
reporting period from January 1 through June 30 or the semiannual 
reporting period from July 1 through December 31.
    (4) Each subsequent compliance report must be postmarked or 
delivered no later than July 31 or January 31, whichever date comes 
first after the end of the semiannual reporting period.
    (5) For each affected source, if your title V permitting authority 
has established dates for submitting semiannual reports pursuant to 40 
CFR 70.6(a)(3)(iii)(A) or 40 CFR 71.6(a)(3)(iii)(A), you may submit the 
first and subsequent compliance reports according to the dates the 
permitting authority has established instead of according to the dates 
in paragraphs (a)(1) through (4) of this section.
    (b) Compliance report contents. Each compliance report must contain 
the information in paragraphs (b)(1) through (3) of this section, and 
as applicable, paragraphs (b)(4) through (8) of this section.
    (1) Company name and address.
    (2) Statement by a responsible official, with that official's name, 
title, and signature, certifying the truth, accuracy, and completeness 
of the content of the report.

[[Page 44704]]

    (3) Date of report and beginning and ending dates of the reporting 
period.
    (4) If you had a startup, shutdown or malfunction during the 
reporting period and you took actions consistent with your startup, 
shutdown, and malfunction plan, the compliance report must include the 
information in Sec. 63.10(d)(5)(i).
    (5) If there were no deviations from the continuous compliance 
requirements in Sec. 63.8246 that apply to you, a statement that there 
were no deviations from the emission limitations and work practice 
standards during the reporting period.
    (6) If there were no periods during which the mercury concentration 
CMS was out-of-control as specified in Sec. 63.8(c)(7), a statement 
that there were no periods during the which the mercury concentration 
CMS was out-of-control during the reporting period.
    (7) For each deviation from the requirements for work practice 
standards in Tables 1 through 5 to this subpart that occurs at an 
affected source (including deviations where the response intervals were 
not adhered to as described in Sec. 63.8192(c)), the compliance report 
must contain the information in paragraphs (b)(1) through (4) of this 
section and the information in paragraphs (b)(7)(i) and (ii) of this 
section. This includes periods of startup, shutdown, and malfunction.
    (i) The total operating time of each affected source during the 
reporting period.
    (ii) Information on the number, duration, and cause of deviations 
(including unknown cause, if applicable), as applicable, and the 
corrective action taken.
    (8) For each deviation from an emission limitation (emission limit 
and operating limit) occurring at an affected source where you are 
using a mercury concentration CMS, in accordance with the site-specific 
monitoring plan required in Sec. 63.8242(c), to comply with the 
emission limitation in this subpart, you must include the information 
in paragraphs (b)(1) through (4) of this section and the information in 
paragraphs (b)(8)(i) through (xii) of this section. This includes 
periods of startup, shutdown, and malfunction.
    (i) The date and time that each malfunction started and stopped.
    (ii) The date and time of each instance in which a continuous 
monitoring system was inoperative, except for zero (low-level) and 
high-level checks.
    (iii) The date, time, and duration of each instance in which a 
continuous monitoring system was out-of-control, including the 
information in Sec. 63.8(c)(8).
    (iv) The date and time that each deviation started and stopped, and 
whether each deviation occurred during a period of startup, shutdown, 
or malfunction or during another period.
    (v) A summary of the total duration of the deviation during the 
reporting period and the total duration as a percent of the total 
source operating time during that reporting period.
    (vi) A breakdown of the total duration of the deviations during the 
reporting period including those that are due to startup, shutdown, 
control equipment problems, process problems, other known causes, and 
other unknown causes.
    (vii) A summary of the total duration of continuous monitoring 
system downtime during the reporting period and the total duration of 
monitoring system downtime as a percent of the total source operating 
time during the reporting period.
    (viii) An identification of each hazardous air pollutant that was 
monitored at the affected source.
    (ix) A brief description of the process units.
    (x) A brief description of the continuous monitoring system.
    (xi) The date of the latest continuous monitoring system 
certification or audit.
    (xii) A description of any changes in monitoring system, processes, 
or controls since the last reporting period.
    (c) Immediate startup, shutdown, and malfunction report. If you had 
a startup, shutdown, or malfunction during the semiannual reporting 
period that was not consistent with your startup, shutdown, and 
malfunction plan required in Sec. 63.8226(c), you must submit an 
immediate startup, shutdown, and malfunction report according to the 
requirements in Sec. 63.10(d)(5)(ii).
    (d) Part 70 monitoring report. For each affected source, you must 
report all deviations as defined in this subpart in the semiannual 
monitoring report required by 40 CFR 70.6(a)(3)(iii)(A) or 40 CFR 
71.6(a)(3)(iii)(A). If you submit a compliance report for an affected 
source along with, or as part of, the semiannual monitoring report 
required by 40 CFR 70.6(a)(3)(iii)(A) or 40 CFR 71.6(a)(3)(iii)(A), and 
the compliance report includes all required information concerning 
deviations from any emission limitation and work practice standard in 
this subpart, submission of the compliance report satisfies any 
obligation to report the same deviations in the semiannual monitoring 
report. However, submission of a compliance report does not otherwise 
affect any obligation you may have to report deviations from permit 
requirements for an affected source to your permitting authority.


Sec. 63.8256  What records must I keep?

    (a) General records. You must keep the records in paragraphs (a)(1) 
and (2) of this section.
    (1) A copy of each notification and report that you submitted to 
comply with this subpart, including all documentation supporting any 
initial notification or notification of compliance status that you 
submitted, according to the requirements in Sec. 63.10(b)(2)(xiv).
    (2) The records in Sec. 63.6(e)(3)(iii) through (v) related to 
startup, shutdown, and malfunction.
    (b) Records associated with the by-product hydrogen stream and end-
box ventilation system vent emission limitations and the mercury 
thermal recovery unit vent emission limitations. You must keep the 
records in paragraphs (b)(1) through (5) of this section related to the 
emission limitations in Sec. 63.8190(a)(2) through (3) and (b).
    (1) Records of performance tests as required in 
Sec. 63.10(b)(2)(viii).
    (2) Records of the establishment of the applicable mercury 
concentration operating limits, including records of the mercury 
concentration monitoring conducted during the performance tests.
    (3) Records of the continuous mercury concentration monitoring 
data.
    (4) Records of the daily average elemental mercury concentration 
values.
    (5) Records associated with your site-specific monitoring plan 
required in Sec. 63.8242(c) (i.e., results of inspections, 
calibrations, and validation checks of each mercury concentration CMS).
    (c) Records associated with the work practice standards. You must 
keep the records specified in Table 8 to this subpart related to the 
work practice standards in Tables 1 through 5 to this subpart. You must 
also maintain a copy of your current washdown plan and records of when 
each washdown occurs.


Sec. 63.8258  In what form and how long must I keep my records?

    (a) Your records must be in a form suitable and readily available 
for expeditious review, according to Sec. 63.10(b)(1).
    (b) As specified in Sec. 63.10(b)(1), you must keep each record for 
5 years following the date of each occurrence, measurement, 
maintenance, corrective action, report, or record.
    (c) You must keep each record on site for at least 2 years after 
the date of each occurrence, measurement, maintenance, corrective 
action, report, or record,

[[Page 44705]]

according to Sec. 63.10(b)(1). You can keep the records offsite for the 
remaining 3 years.

Other Requirements and Information


Sec. 63.8262  What parts of the General Provisions apply to me?

    Table 9 to this subpart shows which parts of the General Provisions 
in Secs. 63.1 through 63.13 apply to you.


Sec. 63.8264  Who implements and enforces this subpart?

    (a) This subpart can be implemented and enforced by us, the United 
States Environmental Protection Agency (U.S. EPA), or a delegated 
authority such as your State, local, or tribal agency. If the U.S. EPA 
Administrator has delegated authority to your State, local, or tribal 
agency, then that agency has the authority to implement and enforce 
this subpart. You should contact your U.S. EPA Regional Office to find 
out if this subpart is delegated to your State, local, or tribal 
agency.
    (b) In delegating implementation and enforcement authority of this 
subpart to a State, local, or tribal agency under subpart E of this 
part, the authorities contained in paragraph (c) of this section are 
retained by the Administrator of U.S. EPA and are not transferred to 
the State, local, or tribal agency.
    (c) The authorities in paragraphs (c)(1) through (4) of this 
section will not be delegated to State, local, or tribal agencies.
    (1) Approval of alternatives under Sec. 63.6(g) to the non-opacity 
emission limitations in Sec. 63.8190 and work practice standards in 
Sec. 63.8192.
    (2) Approval of major alternatives to test methods under 
Sec. 63.7(e)(2)(ii) and (f) and as defined in Sec. 63.90.
    (3) Approval of major alternatives to monitoring under Sec. 63.8(f) 
and as defined in Sec. 63.90.
    (4) Approval of major alternatives to recordkeeping and reporting 
under Sec. 63.10(f) and as defined in Sec. 63.90.


Sec. 63.8266  What definitions apply to this subpart?

    Terms used in this subpart are defined in the Clean Air Act, in 
Sec. 63.2, and in this section as follows:
    Aqueous liquid means a liquid mixture in which water is the 
predominant component.
    Brine means an aqueous solution of alkali metal chloride, as sodium 
chloride salt solution or potassium chloride salt solution, that is 
used in the electrolyzer as a raw material.
    By-product hydrogen stream means the hydrogen gas from each 
decomposer that passes through the hydrogen system and is burned as 
fuel, transferred to another process as raw material, or discharged 
directly to the atmosphere.
    Caustic means an aqueous solution of alkali metal hydroxide, as 
sodium hydroxide or potassium hydroxide, that is produced in the 
decomposer.
    Caustic basket means a fixture adjacent to the decomposer that 
contains a serrated funnel over which the caustic from the decomposer 
passes, breaking into droplets such that electric current is 
interrupted.
    Caustic system means all vessels, piping, and equipment that convey 
caustic and remove mercury from the caustic stream. The caustic system 
begins at the decomposer and ends after the primary filters.
    Cell room means a building or other structure in which one or more 
mercury cells are located.
    Control device means a piece of equipment (such as condensers, 
coolers, chillers, heat exchangers, mist eliminators, absorption units, 
and adsorption units) that removes mercury from gaseous streams.
    Decomposer means the component of a mercury cell in which mercury 
amalgam and water react in bed of graphite packing (within a 
cylindrical vessel), producing caustic and hydrogen gas and returning 
mercury to its elemental form for re-use in the process.
    Deviation means any instance in which an affected source subject to 
this subpart, or an owner or operator of such a source:
    (1) Fails to meet any requirement or obligation established by this 
subpart including, but not limited to, any emission limitation 
(including any operating limit) or work practice standard;
    (2) Fails to meet any term or condition that is adopted to 
implement an applicable requirement in this subpart and that is 
included in the operating permit for any affected source required to 
obtain such a permit; or
    (3) Fails to meet any emission limitation (including any operating 
limit) or work practice standard in this subpart during startup, 
shutdown, or malfunction, regardless or whether or not such failure is 
permitted by this subpart.
    Electrolyzer means the main component of the mercury cell that 
consists of an elongated, shallow steel trough that holds a layer of 
mercury as a flowing cathode. The electrolyzer is enclosed by side 
panels and a top that suspends metal anodes. In the electrolyzer, brine 
is fed between a flowing mercury cathode and metal anodes in the 
presence of electricity to produce chlorine gas and an alkali metal-
mercury amalgam (mercury amalgam).
    Emission limitation means any emission limit or operating limit.
    End box means a component of a mercury cell for transferring 
materials between the electrolyzer and the decomposer. The inlet end 
box collects and combines raw materials at the inlet end of the cell, 
and the outlet end box separates and directs various materials either 
into the decomposer or out of the cell.
    End-box ventilation system means all vessels, piping, and equipment 
that evacuate the head space of each mercury cell end box (and possibly 
other vessels and equipment) to the atmosphere. The end-box ventilation 
system begins at the end box (and other vessel or equipment which is 
being evacuated) and terminates at the end-box ventilation system vent. 
The end-box ventilation system includes all control devices.
    End-box ventilation system vent means the discharge point of the 
end-box ventilation system to the atmosphere after all control devices.
    Hydrogen leak means hydrogen gas (containing mercury vapor) that is 
escaping from the decomposer or hydrogen system.
    Hydrogen system means all vessels, piping, and equipment that 
convey a by-product hydrogen stream. The hydrogen system begins at the 
decomposer and ends at the point where the by-product hydrogen stream 
is either burned as fuel, transferred to another process as raw 
material, or discharged directly to the atmosphere. The hydrogen system 
includes all control devices.
    In liquid mercury service means containing or coming in contact 
with liquid mercury.
    Liquid mercury accumulation means one or more liquid mercury 
droplets, or a pool of liquid mercury, present on the floor or other 
surface exposed to the atmosphere.
    Liquid mercury leak means the liquid mercury that is dripping or 
otherwise escaping from process equipment.
    Liquid mercury spill means a liquid mercury accumulation resulting 
from a liquid mercury that leaked from process equipment or that 
dripped during maintenance or handling.
    Mercury cell means a device consisting of an electrolyzer and 
decomposer, with one or more end boxes, a mercury pump, and other 
components linking the electrolyzer and decomposer.
    Mercury cell amalgam seal pot means a compartment through which 
mercury amalgam passes from an outlet end box to a decomposer.

[[Page 44706]]

    Mercury cell chlor-alkali plant means all contiguous or adjoining 
property that is under common control, where mercury cells are used to 
manufacture product chlorine, product caustic, and by-product hydrogen 
and where mercury may be recovered from wastes.
    Mercury cell chlor-alkali production facility means an affected 
source consisting of all cell rooms and ancillary operations used in 
the manufacture of product chlorine, product caustic, and by-product 
hydrogen at a mercury cell chlor-alkali plant.
    Mercury concentration CMS, or mercury concentration continuous 
monitoring system, means a CMS, as defined in Sec. 63.2, that 
continuously measures the concentration of mercury.
    Mercury-containing wastes means waste materials containing mercury, 
which are typically classified under Resource Conservation and Recovery 
Act (RCRA) solid waste designations. K071 wastes are sludges from the 
brine system. K106 are wastewater treatment sludges. D009 wastes are 
non-specific mercury-containing wastes, further classified as either 
debris or nondebris (i.e., cell room sludges and carbon from 
decomposers).
    Mercury pump means a component of a mercury cell for conveying 
elemental mercury re-created in the decomposer to the beginning of the 
mercury cell. A mercury pump is typically found either as an in-line 
mercury pump (near a mercury suction pot or mercury seal pot) or 
submerged mercury pump (within a mercury pump tank or mercury pump 
seal).
    Mercury recovery facility means an affected source consisting of 
all processes and associated operations needed for mercury recovery 
from wastes at a mercury cell chlor-alkali plant.
    Mercury thermal recovery unit means the retort(s) where mercury-
containing wastes are heated to volatilize mercury and the mercury 
recovery/control system (control devices and other equipment) where the 
retort off-gas is cooled, causing mercury to condense and liquid 
mercury to be recovered.
    Mercury thermal recovery unit vent means the discharge point of the 
mercury thermal recovery unit to the atmosphere after all recovery/
control devices. This term encompasses both oven type vents and non-
oven type vents.
    Mercury vacuum cleaner means a cleanup device used to draw a liquid 
mercury spill or accumulation (via suction pressure) into a closed 
compartment.
    Non-oven type mercury thermal recovery unit vent means the 
discharge point to the atmosphere after all recovery/control devices of 
a mercury thermal recovery unit in which the retort is either a rotary 
kiln or single hearth retort.
    Open-top container means any container that does not have a tight-
fitting cover that keeps its contents from being exposed to the 
atmosphere.
    Oven type mercury thermal recovery unit vent means the discharge 
point to the atmosphere after all recovery/control devices of a mercury 
thermal recovery unit in which each retort is a batch oven retort.
    Responsible official means responsible official as defined in 40 
CFR 70.2.
    Retort means a furnace where mercury-containing wastes are heated 
to drive mercury into the gas phase. The types of retorts used as part 
of mercury thermal recovery units at mercury cell chlor-alkali plants 
include batch oven retorts, rotary kilns, and single hearth retorts.
    Spalling means fragmentation by chipping.
    Sump means a large reservoir or pit for wastewaters (primarily 
washdown waters).
    Trench means a narrow channel or depression built into the length 
of a cell room floor that leads washdown materials to a drain.
    Vent hose means a connection for transporting gases from the 
mercury cell.
    Washdown means the act of rinsing a floor or surface with a stream 
of aqueous liquid to cleanse it of a liquid mercury spill or 
accumulation, generally by driving it into a trench.
    Work practice standard means any design, equipment, work practice, 
or operational standard, or combination thereof, that is promulgated 
pursuant to section 112(h) of the Clean Air Act.

Tables to Subpart IIIII of Part 63

    As stated in Sec. 63.8192, you must meet the work practice 
standards in the following table:

  Table 1 to Subpart IIIII of Part 63--Work Practice Standards--Design, Operation, and Maintenance Requirements
----------------------------------------------------------------------------------------------------------------
                  For . . .                                             You must . . .
----------------------------------------------------------------------------------------------------------------
1. Cell rooms...............................  a. Construct each cell room interior using materials that are
                                               resistant to absorption of mercury, resistant to corrosion,
                                               facilitate the detection of liquid mercury spills or
                                               accumulations, and are easy to clean.
                                              b. Limit access around and beneath mercury cells in each cell room
                                               to prevent liquid mercury from being tracked into other areas.
                                              c. Provide adequate lighting in each cell room to facilitate the
                                               detection of liquid mercury spills or accumulations.
                                              d. Minimize the number of items stored in each cell room.
2. Mercury cells and electrolyzers..........  a. Operate and maintain each electrolyzer, decomposer, end box,
                                               and mercury pump to minimize leakage of mercury.
                                              b. Prior to opening an electrolyzer for maintenance, do the
                                               following: (1) complete work that can be done before opening the
                                               electrolyzer in order to minimize the time required to complete
                                               maintenance when the electrolyzer is open (e.g., removing bolts
                                               from a side panel while the electrolyzer is cooling); (2) fill
                                               the electrolyzer with an aqueous liquid; (3) allow the
                                               electrolyzer to cool before opening; and (4) schedule and staff
                                               maintenance of the electrolyzer to minimize the time the
                                               electrolyzer is open.
                                              c. When the electrolyzer top is raised and before moving the top
                                               and anodes, thoroughly flush all visible mercury from the top and
                                               the anodes with an aqueous liquid.
                                              d. While an electrolyzer is open, keep the bottom covered with an
                                               aqueous liquid or maintain a continuous flow of aqueous liquid.
                                              e. During an electrolyzer side panel change, take measures to
                                               ensure an aqueous liquid covers or flows over the bottom.
                                              f. Each time an electrolyzer is opened, inspect and replace
                                               components, as appropriate.

[[Page 44707]]

 
                                              g. If you step into an electrolyzer bottom, either remove all
                                               visible mercury from your footwear or replace them immediately
                                               after stepping out of the electrolyzer.
                                              h. If an electrolyzer is disassembled for overhaul maintenance or
                                               for any other reason, chemically clean the bed plate or
                                               thoroughly flush it with an aqueous liquid.
                                              i. Before transporting each electrolyzer part to another work
                                               area, remove all visible mercury from the part or contain the
                                               part to prevent mercury from dripping during transport.
                                              j. After completing maintenance on an electrolyzer, check any
                                               mercury piping flanges that were opened for liquid mercury leaks.
                                              k. If a liquid mercury spill occurs during any maintenance
                                               activity on an electrolyzer, clean it up in accordance with the
                                               requirements in Table 3 to this subpart.
3. Vessels in liquid mercury service........  If you replace a vessel containing mercury that is intended to
                                               trap and collect mercury after [DATE OF PUBLICATION OF THE FINAL
                                               RULE IN THE Federal Register], replace it with a vessel that has
                                               a cone shaped bottom with a drain valve or other design that
                                               readily facilitates mercury collection.
4. Piping and process lines in liquid         a. Use piping with smooth interiors to avoid liquid mercury
 mercury service.                              buildups within the pipe.
                                              b. To prevent mercury buildup after [DATE OF PUBLICATION OF THE
                                               FINAL RULE IN THE Federal Register], equip each new process line
                                               and piping system with adequate low point drains or mercury knock-
                                               out pots to facilitate mercury collection and recovery.
5. Cell room floors.........................  a. Maintain a coating on cell room floors that is resistant to
                                               absorption of mercury and that facilitates the detection of
                                               liquid mercury spills or accumulations.
                                              b. Maintain cell room floors such that they are smooth and free of
                                               cracking and spalling.
                                              c. Maintain troughs and trenches to prevent mercury accumulation
                                               in the corners.
                                              d. Maintain a layer of aqueous liquid on liquid mercury contained
                                               in trenches or drains and replenish the aqueous layer at least
                                               once per day.
                                              e. Keep the cell room floor clean and free of debris.
                                              f. If you step into a liquid mercury spill or accumulation, either
                                               remove all visible mercury from your footwear or replace your
                                               footwear immediately.
6. End boxes................................  a. Either equip each end box with a fixed cover that is leak
                                               tight, or route the end box head space to an end-box ventilation
                                               system.
                                              b. For each end-box ventilation system: (1) maintain a flow of
                                               aqueous liquid over the liquid mercury in the end box and
                                               maintain the temperature of the aqueous liquid below its boiling
                                               point, (2) maintain a negative pressure in the end-box
                                               ventilation system, and (3) maintain the end-box ventilation
                                               system in good condition.
                                              c. Maintain each end-box cover in good condition and keep the end
                                               box closed when the cell is in service and when liquid mercury is
                                               flowing down the cell, except when operation or maintenance
                                               activities require short- term access.
                                              d. Keep all bolts and C-clamps used to hold the covers in place
                                               when the cell is in service and when liquid mercury is flowing
                                               down the cell.
                                              e. Maintain each access port stopper in an end-box cover in good
                                               sealing condition and keep each end-box access port closed when
                                               the cell is in service and when liquid mercury is flowing down
                                               the cell.
7. Decomposers..............................  a. Maintain each decomposer cover in good condition and keep each
                                               decomposer closed and sealed, except when maintenance activities
                                               require the cover to be removed.
                                              b. Maintain leak-tight connections between the decomposer and the
                                               corresponding cell components, hydrogen system piping, and
                                               caustic system piping, except when maintenance activities require
                                               access to these connections.
                                              c. Keep each mercury cell amalgam seal pot closed and sealed,
                                               except when operation or maintenance activities require short-
                                               term access.
                                              d. Prior to opening a decomposer, do the following: (1) fill the
                                               decomposer with an aqueous liquid or drain the decomposer liquid
                                               mercury into a container that meets requirements listed below for
                                               closed containers, (2) allow the decomposer to cool before
                                               opening, and (3) complete work that can be done before opening
                                               the decomposer.
                                              e. Take precautions to avoid mercury spills when changing graphite
                                               grids or balls in horizontal decomposers or graphite packing in
                                               vertical decomposers. If a spill occurs, you must clean it up in
                                               accordance with the requirements in Table 3 to this subpart.
                                              f. After each maintenance activity, use an appropriate technique
                                               (see Table 7 to this subpart) to check for hydrogen leaks.
                                              g. Before transporting any internal part from the decomposer (such
                                               as the graphite basket) to another work area, remove all visible
                                               mercury from the part or contain the part to prevent mercury from
                                               dripping during transport.
                                              h. Store carbon from decomposers in accordance with the
                                               requirements in Table 5 to this subpart until the carbon is
                                               treated or is disposed.
8. Submerged mercury pumps..................  a. Provide a vapor outlet connection from each submerged pump to
                                               an end-box ventilation system. The connection must be maintained
                                               under negative pressure.
                                              b. Keep each mercury pump tank closed, except when maintenance or
                                               operation activities require the cover to be removed.
                                              c. Maintain a flow of aqueous liquid over the liquid mercury in
                                               each mercury pump tank and maintain the aqueous liquid at a
                                               temperature below its boiling point.

[[Page 44708]]

 
9. Containers holding liquid mercury........  Maintain a layer of aqueous liquid over liquid mercury containers
                                               in each open-top container. Replenish the aqueous layer holding
                                               liquid at least once per day and collect the liquid mercury
                                               mercury from the container in accordance with the requirements in
                                               Table 4 to this subpart.
10. Containers used to store liquid mercury.  a. Store liquid mercury in containers with tight fitting covers.
                                              b. Maintain the seals on the covers in good condition.
                                              c. Keep each container securely closed when mercury is not being
                                               added to, or removed from, the container.
11. Caustic systems.........................  a. Maintain the seal between each caustic basket cover and caustic
                                               basket by using gaskets and other appropriate material.
                                              b. Prevent solids and liquids collected from back-flushing each
                                               primary caustic filter to contact floors or run into open
                                               trenches.
                                              c. Collect solids and liquids from back-flushing each primary
                                               caustic filter and store these mercury-containing wastes in
                                               accordance with the requirements in Table 5 to this subpart.
                                              d. Keep each caustic basket closed and sealed, except when
                                               operation or maintenance activities require short term access.
12. Hydrogen systems........................  a. Collect drips from each hydrogen seal pot and compressor seal
                                               in containers meeting the requirements in this table for open
                                               containers. These drips should not be allowed to run on the floor
                                               or in open trenches.
                                              b. Minimize purging of hydrogen from a decomposer into the cell
                                               room by either sweeping the decomposer with an inert gas or by
                                               routing the hydrogen to the hydrogen system.
                                              c. Maintain hydrogen piping gaskets in good condition.
                                              d. After any maintenance activities, use an appropriate technique
                                               (see Table 7 to this subpart) to check all hydrogen piping
                                               flanges that were opened for hydrogen leaks.
----------------------------------------------------------------------------------------------------------------

    As stated in Sec. 63.8192, you must meet the work practice 
standards in the following table:

               Table 2 to Subpart IIIII of Part 63.--Work Practice Standards--Required Inspections
----------------------------------------------------------------------------------------------------------------
                                 At least once
    You must inspect . . .        each . . .          And if you find . . .               You must . . .
----------------------------------------------------------------------------------------------------------------
1. Each vent hose on each      12 hours........  a leaking vent hose............  take action immediately to
 mercury cell.                                                                     correct the leak.
2. Each open-top container     12 hours........  liquid mercury that is not       take action immediately to
 holding liquid mercury.                          covered by an aqueous liquid.    cover the liquid mercury with
                                                                                   an aqueous liquid.
3. Each end box..............  12 hours........  a. an end-box cover not          take action immediately to put
                                                  securely in place.               the end-box cover securely in
                                                                                   place.
                                                 b. an end-box stopper not        take action immediately to put
                                                  securely in place.               the end-box stopper securely
                                                                                   in place.
                                                 c. liquid mercury in an end box  take action immediately to
                                                  that is not covered by an        cover the liquid mercury with
                                                  aqueous liquid at a              an aqueous liquid.
                                                  temperature below boiling.
4. Each mercury amalgam seal   12 hours........  a seal pot cover that is not     take action immediately to put
 pot.                                             securely in place.               the seal pot cover securely
                                                                                   in place.
5. Each mercury seal pot.....  12 hours........  a mercury seal pot stopper not   take action immediately to put
                                                  securely in place.               the mercury seal pot stopper
                                                                                   securely in place.
6. Cell room floors..........  month...........  cracks, spalling, or other       repair the crack, spalling, or
                                                  deficiencies that could cause    other deficiency within 1
                                                  liquid mercury to become         month from the time you
                                                  trapped.                         identify the deficiency.
7. Pillars and beams.........  6 months........  cracks, spalling, or other       repair the crack, spalling, or
                                                  deficiencies that could cause    other deficiency within 1
                                                  liquid mercury to become         month from the time you
                                                  trapped.                         identify the deficiency.
8. Each caustic basket.......  12 hours........  a caustic basket cover that is   take action immediately to put
                                                  not securely in place.           the caustic basket cover
                                                                                   securely in place.
9. All equipment and piping    24 hours........  equipment that is leaking        initiate repair of the leaking
 in the caustic system.                           caustic.                         equipment within 72 hours
                                                                                   from the time that you
                                                                                   identify the caustic leak.
10. All floors and other       12 hours........  a liquid mercury spill or        take the required action
 surfaces where liquid                            accumulation.                    specified in Table 3 to this
 mercury could accumulate in                                                       subpart.
 cell rooms and other
 production facilities and in
 mercury recovery facilities.

[[Page 44709]]

 
11. Each electrolyzer bottom,  24 hours........  equipment that is leaking        take the required action
 electrolyzer side panel, end                     liquid mercury.                  specified in Table 3 to this
 box, mercury amalgam seal                                                         subpart.
 pot, decomposer, mercury
 pump, and hydrogen cooler,
 and all other vessels,
 piping, and equipment in
 liquid mercury service in
 the cell room.
12. Each decomposer and all    12 hours........  equipment that is leaking        take the required action
 hydrogen piping up to the                        hydrogen and/or mercury vapor.   specified in Table 3 to this
 hydrogen header.                                                                  subpart.
13. All equipment in the       3 months........  equipment that is leaking        take the required action
 hydrogen system from the                         hydrogen and/or mercury vapor.   specified in Table 3 to this
 start of the header to the                                                        subpart.
 last control device.
----------------------------------------------------------------------------------------------------------------
Note: See Table 7 of this subpart for examples of techniques for conducting the inspections required in this
  table.

    As stated in Sec. 63.8192, you must meet the work practice 
standards in the following table:

  Table 3 to Subpart IIIII of Part 63.--Work Practice Standards--Required Actions for Liquid Mercury Spills and
                               Accumulations and Hydrogen and Mercury Vapor Leaks
----------------------------------------------------------------------------------------------------------------
During a required inspection or at any other
           time, if you find . . .                                      You must . . .
----------------------------------------------------------------------------------------------------------------
1. A liquid mercury spill or accumulation...  a. Initiate clean up of the liquid mercury spill or accumulation
                                               as soon as possible, but no later than 1 hour from the time you
                                               detect it.
                                              b. Clean up liquid mercury using: (1) a mercury vacuum cleaner,
                                               (2) by washing the mercury to the nearest trench or sump, or (3)
                                               by using an alternative method. If you use an alternative method
                                               to clean up liquid mercury, you must submit a description of the
                                               method to the Administrator in your Notification of Compliance
                                               Status report.
                                              c. If you use a mercury vacuum cleaner: (1) the vacuum cleaner
                                               must be designed to prevent generation of airborne mercury, (2)
                                               you must cap the ends of hoses after each use, and (3) after
                                               vacuuming, you must wash down the area.
                                              d. Inspect all equipment in liquid mercury service in the
                                               surrounding area to identify the source of the liquid mercury
                                               within 1 hour from the time you detect the liquid mercury spill
                                               or accumulation.
                                              e. If you identify leaking equipment as the source of the spill or
                                               accumulation, contain the dripping mercury, stop the leak, and
                                               repair the leaking equipment as specified below.
                                              f. If you cannot identify the source of the liquid mercury spill
                                               or accumulation, re-inspect the area within 6 hours of the time
                                               you detected the liquid mercury spill or accumulation, or within
                                               6 hours of the last inspection of the area.
2. Equipment that is leaking liquid mercury.  a. Contain the liquid mercury dripping from the leaking equipment
                                               by placing a container under the leak within 30 minutes from the
                                               time you identify the liquid mercury leak.
                                              b. The container must meet the requirement for open-top containers
                                               in Table 1 to this subpart.
                                              c. Make a first attempt at stopping the leak within 1 hour from
                                               the time you identify the liquid mercury leak.
                                              d. Stop the leak and repair the leaking equipment within 4 hours
                                               from the time you identify the liquid mercury leak.
                                              e. You can delay repair of equipment leaking liquid mercury if you
                                               either: (1) isolate the leaking equipment from the process so
                                               that it does not remain in mercury service; or (2) determine that
                                               you cannot repair the leaking equipment without taking the cell
                                               off line, provided that you contain the dripping mercury at all
                                               times as described above, and take the cell off line as soon as
                                               practicable, but no later than 48 hours from the time you
                                               identify the leaking equipment. You cannot place the cell back
                                               into service until the leaking equipment is repaired.
3. A decomposer or hydrogen system piping up  a. Make a first attempt at stopping the leak within 1 hour from
 to the hydrogen header that is leaking        the time you identify the hydrogen and/or mercury vapor leak.
 hydrogen and/or mercury vapor.
                                              b. Stop the leak and repair the leaking equipment within 4 hours
                                               from the time you identify the hydrogen and/or mercury vapor
                                               leak.
                                              c. You can delay repair of equipment leaking hydrogen and/or
                                               mercury vapor if you isolate the leaking equipment or take the
                                               cell off line until you repair the leaking equipment.
4. Equipment in the hydrogen system, from     a. Make a first attempt at stopping the leak within 4 hours from
 the start of the hydrogen header to the       the time you identify the hydrogen and/or mercury vapor leak.
 last control device, that is leaking
 hydrogen and/or mercury vapor.
                                              b. Stop the leak and repair the header within 24 hours from the
                                               time you identify the hydrogen and/or mercury vapor leak.

[[Page 44710]]

 
                                              c. You can delay repair of equipment leaking hydrogen and/or
                                               mercury vapor if you isolate the leaking equipment.
----------------------------------------------------------------------------------------------------------------

    As stated in Sec. 63.8192, you must meet the work practice 
standards in the following table:

    Table 4 to Subpart IIIII of Part 63.--Work Practice Standards--Requirements for Mercury Liquid Collection
----------------------------------------------------------------------------------------------------------------
                                                                                  Additional requirements
 You must collect liquid mercury         When                            ---------------------------------------
           from . . .
----------------------------------------------------------------------------------------------------------------
1. Open-top containers..........  a. at least once    i. If you spill     (1) From the time   (A) Within 4 hours
                                   each 72 hours.      liquid mercury      that you collect    from the time you
                                                       during collection   liquid mercury      collect the
                                                       or transport, you   into a temporary    liquid mercury,
                                                       must take the       container until     you must transfer
                                                       action specified    the time that you   it from each
                                                       in Table 3 to       store the liquid    temporary
                                                       this subpart for    mercury, you must   container to a
                                                       liquid mercury      keep it covered     storage container
                                                       spills and          by an aqueous       that meets the
                                                       accumulations.      liquid.             specifications in
                                                                                               Table 1 to this
                                                                                               subpart.
2. Vessels, low point drains,     a. at least once    See 1.a.i. above..  See 1.a.i.(1)       See 1.a.i.(A)
 mercury knock-out pots, and       each week.                              above.              above.
 other closed mercury collection
 points.
3. All other equipment..........  a. whenever         See 1.a.i. above..  See 1.a.i.(1)       See 1.a.i.(A)
                                   maintenance                             above.              above.
                                   activities
                                   require the
                                   opening of the
                                   equipment.
----------------------------------------------------------------------------------------------------------------

    As stated in Sec. 63.8192, you must meet the work practice 
standards in the following table:

      Table 5 to Subpart IIIII of Part 63.--Work Practice Standards--Requirements for Handling and Storage of
                                            Mercury-Containing Wastes
----------------------------------------------------------------------------------------------------------------
                  For . . .                                             You must . . .
----------------------------------------------------------------------------------------------------------------
1. Carbon media from decomposers and cell     a. Store wastes in closed containers, or
 room sludges.
                                              b. Maintain a layer of aqueous liquid over wastes in open-top
                                               containers and replenish the aqueous layer at least once per
                                               week.
2. All other mercury-containing wastes......  a. Wash or chemically decontaminate wastes to remove visible
                                               mercury, or
                                              b. Store wastes in closed containers.
----------------------------------------------------------------------------------------------------------------

    As stated in Sec. 63.8192, your written washdown plan must address 
the elements contained in the following table:

    Table 6 to Subpart IIIII of Part 63.--Required Elements of Washdown
                                  Plans
------------------------------------------------------------------------
                                              You must establish the
 For each of the following areas . . .    following as part of your plan
                                                      . . .
------------------------------------------------------------------------
1. Center aisles of cell rooms.........  A description of the manner of
                                          washdown of the area, and the
                                          washdown frequency for the
                                          area.
2. Electrolyzers.
3. End boxes and areas under end boxes.
4. Decomposers and areas under
 decomposers.
5. Caustic baskets and areas around
 caustic baskets.
6. Hydrogen system piping.
7. Basement floor of cell rooms.
8. Tanks.
9. Pillars and beams in cell rooms.
10. Mercury cell repair areas.
11. Maintenance shop areas.
12. Work tables.
13. Castings.
14. Storage areas for mercury-
 containing wastes.
------------------------------------------------------------------------


[[Page 44711]]

    As stated in Tables 1 and 2 of Subpart IIIII, examples of 
techniques for equipment problem identification, leak detection and 
mercury vapor measurements can be found in the following table:

     Table 7 to Subpart IIIII of Part 63.--Examples of Techniques for Equipment Problem Identification, Leak
                                    Detection and Mercury Vapor Measurements
----------------------------------------------------------------------------------------------------------------
            To Detect . . .                   You could use . . .             Principle of detection . . .
----------------------------------------------------------------------------------------------------------------
1. Leaking vent hoses; liquid mercury   Visual inspections.             ........................................
 that is not covered by an aqueous
 liquid in open-top containers or end
 boxes; end-box covers or stoppers,
 amalgam seal pot stoppers, or caustic
 basket covers not securely in place;
 cracks or spalling in cell room
 floors, pillars, or beams; caustic
 leaks; liquid mercury accumulations
 or spills; and equipment that is
 leaking liquid mercury.
2. Equipment that is leaking hydrogen   a. Auditory and visual          ........................................
 and/or mercury vapor during required    inspections.
 by Table 2 to inspections. this
 subpart.
                                        b. Portable mercury vapor       A sample of gas is drawn through a
                                         analyzer--ultraviolet light     detection cell where ultraviolet light
                                         absorption detector..           at 253.7 nanometers (nm) is directed
                                                                         perpendicularly through the sample
                                                                         toward a photodetector. Mercury absorbs
                                                                         the incident light in proportion to its
                                                                         concentration in the air stream.
                                        c. Portable mercury vapor       A sample of gas is drawn through a
                                         analyzer--gold film             detection cell containing a gold film
                                         amalgamation detector..         detector. Mercury amalgamates with the
                                                                         gold film, changing the resistance of
                                                                         the detector in proportion to the
                                                                         mercury concentration in the air
                                                                         sample.
                                        d. Portable short-wave          Ultraviolet light is directed toward a
                                         ultraviolent light,             fluorescent background positioned
                                         fluorescent background--        behind a suspected source of mercury
                                         visual indication..             emissions. Mercury vapor absorbs the
                                                                         ultraviolet light, projecting a dark
                                                                         shadow image on the fluorescent
                                                                         background.
                                        e. Portable combustible gas     ........................................
                                         meter.
3. Level of mercury vapor in the cell   a. Portable mercury vapor       A sample of gas is drawn through a
 room and other areas.                   analyzer--ultraviolet light     detection cell where ultraviolet light
                                         absorption detector.            at 253.7 nanometers (nm) is directed
                                                                         perpendicularly through the sample
                                                                         toward a photodetector. Mercury absorbs
                                                                         the incident light in proportion to its
                                                                         concentration in the air stream.
                                        b. Portable mercury vapor       A sample of gas is drawn through a
                                         analyzer--gold film             detection cell containing a gold film
                                         amalgamation detector.          detector. Mercury amalgamates with the
                                                                         gold film, changing the resistance of
                                                                         the detector in proportion to the
                                                                         mercury concentration in the air
                                                                         sample.
                                        c. Permanganate impingement     A known volume of gas sample is absorbed
                                                                         in potassium permanganate solution.
                                                                         Mercury in the solution is determined
                                                                         using a cold vapor adsorption analyzer,
                                                                         and the concentration of mercury in the
                                                                         gas sample is calculated.
----------------------------------------------------------------------------------------------------------------

    As stated in Sec. 63.8256(c), you must keep the records (related to 
the work practice standards) specified in the following table:

Table 8 to Subpart IIIII of Part 63.--Required Records for Work Practice
                                Standards
------------------------------------------------------------------------
                                          You must record the following
             For each . . .                     information . . .
------------------------------------------------------------------------
1. Inspection required by Table 2 to     Date and time the inspection
 this subpart.                            was conducted.
2. Of the following situations found     a. Description the condition.
 during an inspection required by Table  b. Location of the condition.
 2 to this subpart: leaking of vent      c. Date and time you identify
 hose; open-top container where liquid    the condition.
 mercury is not covered by an aqueous    d. Description of the
 liquid; end-box cover that is not        corrective action taken.
 securely in place; end-box stopper      e. Date and time you
 that is not securely in place; end box   successfully complete the
 where liquid mercury is not covered by   corrective action.
 an aqueous liquid at a temperature
 below boiling; seal pot cover that is
 not securely in place; open or mercury
 seal pot stopper that is not securely
 in place; crack, spalling, or other
 deficiency in a cell room floor,
 pillar, or beam that could cause
 liquid mercury to become trapped; or
 caustic basket that is not securely in
 place.
3. A caustic leak during an inspection   a. Location of the leak.
 required by Table 2 to this subpart.
                                         b. Date and time you identify
                                          the leak.

[[Page 44712]]

 
                                         c. Date and time you
                                          successfully stop the leak and
                                          repair the leaking equipment.
4. Liquid mercury spill or accumulation  a. Location of the liquid
 identified during an inspection          mercury spill or accumulation.
 required by Table 2 to this subpart or
 at any other time.
                                         b. Estimate of the weight of
                                          liquid mercury.
                                         c. Date and time you detect the
                                          liquid mercury spill or
                                          accumulation.
                                         d. Method you use to clean up
                                          the liquid mercury spill or
                                          accumulation.
                                         e. Date and time when you clean
                                          up the liquid mercury spill or
                                          accumulation.
                                         f. Source of the liquid mercury
                                          spill or accumulation.
                                         g. If the source of the liquid
                                          mercury spill or accumulation
                                          is not identified, the time
                                          when you reinspect the area.
5. Liquid mercury leak or hydrogen leak  a. Location of the leak.
 identified during an inspection
 required by Table 2 to this subpart or
 at any other time.
                                         b. Date and time you identify
                                          the leak.
                                         c. If the leak is a liquid
                                          mercury leak, the date and
                                          time that you successfully
                                          contain the dripping liquid
                                          mercury.
                                         d. Date and time you first
                                          attempt to stop the leak.
                                         e. Date and time you
                                          successfully stop the leak and
                                          repair the leaking equipment.
                                         f. If you take a cell off line
                                          or isolate the leaking
                                          equipment, the date and time
                                          you take the cell off line or
                                          isolate the leaking equipment,
                                          and the date and time you put
                                          the cell or isolated equipment
                                          back into service.
6. Carbon media from decomposers and     a. A statement that these
 cell room sludges..                      wastes are stored in closed
                                          containers, or
                                         b. Date and time you replenish
                                          the aqueous layer over these
                                          wastes stored in open-top
                                          containers.
7. All other mercury-containing wastes.  a. A description of how you
                                          remove visible mercury, or
                                         b. A statement that these
                                          wastes are stored in closed
                                          containers.
------------------------------------------------------------------------

    As stated in Sec. 63.8262, you must comply with the applicable 
General Provisions requirements according to the following table:

           Table 9 to Subpart IIIII of Part 63.--Applicability of General Provisions to Subpart IIIII
----------------------------------------------------------------------------------------------------------------
                                                                  Applies to Subpart
             Citation                         Subject                   IIIII                 Explanation
----------------------------------------------------------------------------------------------------------------
Sec.  63.1........................  Applicability.............  Yes..................
Sec.  63.2........................  Definitions...............  Yes..................
Sec.  63.3........................  Units and Abbreviations...  Yes..................
Sec.  63.4........................  Prohibited Activities.....  Yes..................
Sec.  63.5........................  Construction/               Yes..................
                                     Reconstruction.
Sec.  63.6 (a)-(g), (i), (j)......  Compliance with Standards   Yes..................
                                     and Maintenance
                                     Requirements.
Sec.  63.6(h).....................  Compliance with Opacity     No...................  Subpart IIIII does not
                                     and Visible Emission                               have opacity and visible
                                     Standards.                                         emission standards.
Sec.  63.7........................  Performance Testing         Yes..................  Subpart IIIII specifies
                                     Requirements.                                      additional requirements
                                                                                        related to site-specific
                                                                                        test plans and the
                                                                                        conduct of performance
                                                                                        tests.
Sec.  63.8 (a)(1), (a)(3); (b);     Monitoring Requirements...  Yes..................
 (c)(1)-(4), (6)-(8); (d); (e);
 and (f)(1)-(5).
Sec.  63.8(a)(2)..................  Continuous Monitoring       No...................  Subpart IIIII requires a
                                     System (CMS) Requirements.                         site-specific monitoring
                                                                                        plan in lieu of a
                                                                                        promulgated performance
                                                                                        specification for a
                                                                                        mercury concentration
                                                                                        CMS.
Sec.  63.8(a)(4)..................  Additional Monitoring       No...................  Subpart IIIII does not
                                     Requirements for Control                           require flares.
                                     Devices in Sec.  63.11.
Sec.  63.8(c)(5)..................  COMS Minimum Procedures...  No...................  Subpart IIIII does not
                                                                                        have opacity and visible
                                                                                        emission standards.
Sec.  63.8(f)(6)..................  Alternative to Relative     No...................  Subpart IIIII does not
                                     Accuracy Test.                                     require CEMS.
Sec.  63.8(g).....................  Data Reduction............  No...................  Subpart IIIII specifies
                                                                                        mercury concentration
                                                                                        CMS data reduction
                                                                                        requirements.
Sec.  63.9(a)-(e), (g)-(j)........  Notification Requirements.  Yes..................
Sec.  63.9(f).....................  Notification of VE/Opacity  No...................  Subpart IIIII does not
                                     Test.                                              have opacity and visible
                                                                                        emission standards.
Sec.  63.10(a); (b)(1); (b)(2)(i)-  Recordkeeping/Reporting...  Yes..................
 (xii), (xiv); (b)(3); (c); (d)(1)-
 (2), (4)-(5); (e); (f).
Sec.  63.10(b)(2) (xiii)..........  CMS Records for RATA        No...................  Subpart IIIII does not
                                     Alternative.                                       require CEMS.

[[Page 44713]]

 
Sec.  63.10(d)(3).................  Reporting Opacity or VE     No...................  Subpart IIIII does not
                                     Observations.                                      have opacity and visible
                                                                                        emission standards.
Sec.  63.11.......................  Flares....................  No...................  Subpart IIIII does not
                                                                                        require flares.
Sec.  63.12.......................  Delegation................  Yes..................
Sec.  63.13.......................  Addresses.................  Yes..................
Sec.  63.14.......................  Incorporation by Reference  Yes..................
Sec.  63.15.......................  Availability of             Yes..................
                                     Information.
----------------------------------------------------------------------------------------------------------------

[FR Doc. 02-15873 Filed 7-2-02; 8:45 am]
BILLING CODE 6560-50-P