Subpart DD—National Emission Standards for Hazardous 

Air Pollutants from Off-Site Waste and Recovery 

Operations

Contents

§63.680 Applicability and designation of affected sources.

§63.681 Definitions.

§63.682 [Reserved]

§63.683 Standards: General.

§63.684 Standards: Off-site material treatment.

§63.685 Standards: Tanks.

§63.686 Standards: Oil-water and organic-water separators.

§63.687 Standards: Surface impoundments.

§63.688 Standards: Containers.

§63.689 Standards: Transfer systems.

§63.690 Standards: Process vents.

§63.691 Standards: Equipment leaks.

§63.692 [Reserved]

§63.693 Standards: Closed-vent systems and control devices.

§63.694 Testing methods and procedures.

§63.695 Inspection and monitoring requirements.

§63.696 Recordkeeping requirements.

§63.697 Reporting requirements.

§63.698 Implementation and enforcement.

Table 1 to Subpart DD of Part 63—List of Hazardous Air Pollutants (HAP) for Subpart DD 

Table 2 to Subpart DD of Part 63—Applicability of Paragraphs in Subpart A of This Part 63—

General Provisions to Subpart DD 

Table 3 to Subpart DD of Part 63—Tank Control Levels for Tanks at Existing Affected Sources 

as Required by 40 CFR 63.685(b)(1)(i)

Table 4 to Subpart DD of Part 63—Tank Control Levels for Tanks at Existing Affected Sources 

as Required by 40 CFR 63.685(b)(1)(ii)

Table 5 to Subpart DD of Part 63—Tank Control Levels for Tanks at New Affected Sources as 

Required by 40 CFR 63.685(b)(2)

§63.680 Applicability and designation of affected sources.

(a) The provisions of this subpart apply to the owner and operator of a plant site for 

which both of the conditions specified in paragraphs (a)(1) and (a)(2) of this section are 

applicable. If either one of these conditions does not apply to the plant site, then the owner and 

operator of the plant site are not subject to the provisions of this subpart. 
(1) The plant site is a major source of hazardous air pollutant (HAP) emissions as defined 

in 40 CFR 63.2. 

(2) At the plant site is located one or more of operations that receives off-site materials as 

specified in paragraph (b) of this section and the operations is one of the following waste 

management operations or recovery operations as specified in paragraphs (a)(2)(i) through 

(a)(2)(vi) of this section.

(i) A waste management operation that receives off-site material and the operation is 

regulated as a hazardous waste treatment, storage, and disposal facility (TSDF) under either 40 

CFR part 264 or part 265. 

(ii) A waste management operation that treats wastewater which is an off-site material 

and the operation is exempted from regulation as a hazardous waste treatment, storage, and 

disposal facility under 40 CFR 264.1(g)(6) or 40 CFR 265.1(c)(10). 

(iii) A waste management operation that treats wastewater which is an off-site material 

and the operation meets both of the following conditions: 

(A) The operation is subject to regulation under either section 402 or 307(b) of the Clean 

Water Act but is not owned by a “state” or “municipality” as defined by section 502(3) and 

502(4), respectively, of the Clean Water Act; and 

(B) The treatment of wastewater received from off-site is the predominant activity

performed at the plant site.

(iv) A recovery operation that recycles or reprocesses hazardous waste which is an offsite material and the operation is exempted from regulation as a hazardous waste treatment, 

disposal, and storage facility under 40 CFR 264.1(g)(2) or 40 CFR 265.1(c)(6). 

(v) A recovery operation that recycles or reprocesses used solvent which is an off-site 

material and the operation is not part of a chemical, petroleum, or other manufacturing process 

that is required to use air emission controls by another subpart of 40 CFR part 63 or 40 CFR part 

61.

(vi) A recovery operation that re-refines or reprocesses used oil which is an off-site 

material and the operation is regulated under 40 CFR 279 subpart F—Standards for Used Oil 

Processors and Refiners. 

(b) For the purpose of implementing this subpart, an off-site material is a material that 

meets all of the criteria specified in paragraph (b)(1) of this section but is not one of the materials 

specified in paragraph (b)(2) of this section. 

(1) An off-site material is a material that meets all of the criteria specified in paragraphs 

(b)(1)(i) through (b)(1)(iii) of this section. If any one of these criteria do not apply to the 

material, then the material is not an off-site material subject to this subpart. 
(i) The material is a waste, used oil, or used solvent as defined in §63.681 of this subpart;

(ii) The waste, used oil, or used solvent is not produced or generated within the plant site, 

but the material is delivered, transferred, or otherwise moved to the plant site from a location 

outside the boundaries of the plant site; and 

(iii) The waste, used oil, or used solvent contains one or more of the hazardous air 

pollutants (HAP) listed in Table 1 of this subpart based on the composition of the material at the 

point-of-delivery, as defined in §63.681 of this subpart.

(2) For the purpose of implementing this subpart, the following materials are not off-site 

materials: 

(i) Household waste as defined in 40 CFR 258.2. 

(ii) Radioactive mixed waste managed in accordance with all applicable regulations 

under Atomic Energy Act and Nuclear Waste Policy Act authorities. 

(iii) Waste that is generated as a result of implementing remedial activities required under 

the Resource Conservation and Recovery Act (RCRA) corrective action authorities (RCRA 

sections 3004(u), 3004(v), or 3008(h)), Comprehensive Environmental Response, Compensation, 

and Liability Act (CERCLA) authorities, or similar Federal or State authorities. 

(iv) Waste containing HAP that is generated by residential households (e.g., old paint, 

home garden pesticides) and subsequently is collected as a community service by government 

agencies, businesses, or other organizations for the purpose of promoting the proper disposal of 

this waste. 

(v) Waste that is transferred from a chemical manufacturing plant or other facility for 

which the owner or operator of the facility from which the waste is transferred has complied with 

the provisions of the air emission control standards for process wastewater specified by another 

40 CFR part 63 subpart. This exemption does not apply to a source which complies with another 

40 CFR part 63 subpart by transferring its wastewater off-site for control.

(vi) Waste that is transferred from a chemical manufacturing plant, petroleum refinery, or 

coke by-product recovery plant which is subject to 40 CFR part 61, subpart FF—National 

Emission Standards for Benzene Waste Operations, and for which both of the following 

conditions apply to the waste:

(A) The waste is generated at a facility that is not exempted under the provisions of 40 

CFR 61.342(a) from meeting the air emission control standards of 40 CFR part 61, subpart FF; 

and 

(B) The owner or operator of the facility from which the waste is transferred has 

complied with the provisions of 40 CFR 61.342(f)(2).
(vii) Ship ballast water pumped from a ship to an onshore wastewater treatment facility. 

(viii) Hazardous waste that is stored for 10 days or less at a transfer facility in compliance 

with the provisions of 40 CFR 263.12.

(c) Affected sources—(1) Off-site material management units. For each operation 

specified in paragraphs (a)(2)(i) through (a)(2)(vi) of this section that is located at the plant site, 

the affected source is the entire group of off-site material management units associated with the 

operation. An off-site material management unit is a tank, container, surface impoundment, oilwater separator, organic-water separator, or transfer system used to manage off-site material. For 

the purpose of implementing the standards under this subpart, a unit that meets the definition of a 

tank or container but also is equipped with a vent that serves as a process vent for any of the 

processes listed in paragraphs (c)(2)(i) through (c)(2)(vi) of this section is not an off-site material 

management unit but instead is a process vent and is to be included in the appropriate affected 

source group under paragraph (c)(2) of this section. Examples of such a unit may include, but are 

not limited to, a distillate receiver vessel, a primary condenser, a bottoms receiver vessel, a surge 

control tank, a separator tank, and a hot well.

(2) Process vents. For each operation specified in paragraphs (a)(2)(i) through (a)(2)(vi) 

of this section that is located at the plant site, the affected source is the entire group of process 

equipment associated with the process vents for the processes listed in paragraphs (c)(2)(i) 

through (c)(2)(vi) of this section.

(i) Distillation process used for the treatment, recycling, or recovery of off-site material. 

Distillation means a process, either batch or continuous, separating one or more off-site material 

feed streams into two or more exit streams having different component concentrations from 

those in the feed stream or streams. The separation is achieved by the redistribution of the 

components between the liquid and vapor phases as they approach equilibrium within the 

distillation unit.

(ii) Fractionation process used for the treatment, recycling, or recovery of off-site 

material. Fractionation means a liquid mixture separation process or method used to separate a 

mixture of several volatile components of different boiling points in successive stages, each stage

removing from the mixture some proportion of one of the components.

(iii) Thin-film evaporation process used for the treatment, recycling, or recovery of offsite material. Thin-film evaporation means a liquid mixture separation process or method that 

uses a heating surface consisting of a large diameter tube that may be either straight or tapered, 

horizontal or vertical. Liquid is spread on the tube wall by a rotating assembly of blades that 

maintain a close clearance from the wall or actually ride on the film of liquid on the wall.

(iv) Solvent extraction process used for the treatment, recycling, or recovery of off-site 

material. Solvent extraction means a separation process or method in which a solid or a solution 

is contacted with a liquid solvent (the material and the solvent being relatively insoluble in each 

other) to preferentially dissolve and transfer one or more components into the solvent.
(v) Steam stripping process used for the treatment, recycling, or recovery of off-site 

material. Steam stripping means a liquid mixture separation process or method in which 

vaporization of the volatile components of a liquid mixture occurs by the introduction of steam 

directly into the process.

(vi) Gas stripping process used for the treatment, recycling, or recovery of off-site 

material. Gas stripping means a desorption process or method used to transfer one or more 

volatile components from a liquid mixture into a gas stream either with or without the 

application of heat to the liquid. Packed towers, spray towers, and bubble-cap, sieve, or valvetype plate towers are examples of the process configurations used for contacting the gas and a 

liquid.

(3) Equipment leaks. For each operation specified in paragraphs (a)(2)(i) through 

(a)(2)(vi) of this section that is located at the plant site, the affected source is the entire group of 

equipment components for which each component meets all of the conditions specified in 

paragraphs (c)(3)(i) through (c)(3)(iii) of this section. If any one of these conditions do not apply

to an equipment component, then that component is not part of the affected source for equipment 

leaks.

(i) The equipment component is a pump, compressor, agitator, pressure relief device, 

sampling connection system, open-ended valve or line, valve, connector, or instrumentation 

system;

(ii) The equipment component contains or contacts off-site material having a total HAP 

concentration equal to or greater than 10 percent by weight; and 

(iii) The equipment component is intended to operate for 300 hours or more during a 

calendar year in off-site material service, as defined in §63.681 of this subpart.

(d) Facility-wide exemption. The owner or operator of affected sources subject to this 

subpart is exempted from the requirements of §§63.682 through 63.699 of this subpart in 

situations when the total annual quantity of the HAP that is contained in the off-site material 

received at the plant site is less than 1 megagram per year. For a plant site to be exempted under 

the provisions of this paragraph (d), the owner or operator must meet the requirements in 

paragraphs (d)(1) through (d)(3) of this section.

(1) The owner or operator must prepare an initial determination of the total annual HAP 

quantity in the off-site material received at the plant site. This determination is based on the total 

quantity of the HAP listed in Table 1 of this subpart as determined at the point-of-delivery for 

each off-site material stream.

(2) The owner or operator must prepare a new determination whenever the extent of 

changes to the quantity or composition of the off-site material received at the plant site could 

cause the total annual HAP quantity in the off-site material received at the plant site to exceed 

the limit of 1 megagram per year.
(3) The owner or operator must maintain documentation to support the owner's or 

operator's determination of the total annual HAP quantity in the off-site material received at the 

plant site. This documentation must include the basis and data used for determining the HAP 

content of the off-site material.

(e) Compliance dates—(1) Existing sources. The owner or operator of an affected source 

that commenced construction or reconstruction before October 13, 1994, must achieve 

compliance with the provisions of this subpart on or before the date specified in paragraph 

(e)(1)(i),(ii) or (iii) of this section as applicable to the affected source.

(i) For an affected source that commenced construction or reconstruction before October 

13, 1994 and receives off-site material for the first time before February 1, 2000, the owner or 

operator of this affected source must achieve compliance with the provisions of the subpart 

(except §§ 63.685(b)(1)(ii), 63.691(b)(2), and 63.691(c)(3)(i) and (ii) of this subpart) on or 

before February 1, 2000 unless an extension has been granted by the Administrator as provided 

in 40 CFR 63.6(i). These existing affected sources shall be in compliance with the tank

requirements of § 63.685(b)(1)(ii) of this subpart two years after the publication date of the final 

amendments on [DATE OF PUBLICATION OF THE FINAL RULE IN THE FEDERAL 

REGISTER], the equipment leak requirements of § 63.691(b)(2) of this subpart one year after 

the publication date of the final amendments on [DATE OF PUBLICATION OF THE FINAL 

RULE IN THE FEDERAL REGISTER], and the pressure relief device monitoring requirements 

of § 63.691(c)(3)(i) and (ii) of this subpart three years after the publication date of the final 

amendments on[DATE OF PUBLICATION OF THE FINAL RULE IN THE FEDERAL 

REGISTER].

(ii) For an affected source that commenced construction or reconstruction before October 

13, 1994, but receives off-site material for the first time on or after February 1, 2000, but before 

[DATE OF PUBLICATION OF THE FINAL RULE IN THE FEDERAL REGISTER], the 

owner or operator of the affected source must achieve compliance with the provisions of this 

subpart (except §§ 63.685(b)(1)(ii), 63.691(b)(2), and 63.691(c)(3)(i) and (ii) of this subpart)

upon the first date that the affected source begins to manage off-site material. These existing 

affected sources shall be in compliance with the tank requirements of § 63.685(b)(1)(ii) of this 

subpart two years after the publication date of the final amendments on [DATE OF 

PUBLICATION OF THE FINAL RULE IN THE FEDERAL REGISTER], the equipment leak 

requirements of §63.691(b)(2) of this subpart one year after the publication date of the final 

amendments on [DATE OF PUBLICATION OF THE FINAL RULE IN THE FEDERAL 

REGISTER], and the pressure relief device monitoring requirements of § 63.691(c)(3)(i) and (ii)

of this subpart three years after the publication date of the final amendments on [DATE OF 

PUBLICATION OF THE FINAL RULE IN THE FEDERAL REGISTER].

(iii) For an affected source that commenced construction or reconstruction before 

October 13, 1994, but receives off-site material for the first time on or after [DATE OF 

PUBLICATION OF THE FINAL RULE IN THE FEDERAL REGISTER], the owner or 

operator of the affected source must achieve compliance with the provisions of this subpart

(except §§ 63.685 (b)(1)(ii), 63.691(b)(2), and 63.691(c)(3)(i) and (ii) of this subpart) upon the 

first date that the affected source begins to manage off-site material. These existing affected 
sources shall be in compliance with the tank requirements of § 63.685(b)(1)(ii) of this subpart

two years after the publication date of the final amendments [DATE OF PUBLICATION OF 

THE FINAL RULE IN THE FEDERAL REGISTER], the equipment leak requirements of 

§ 63.691(b)(2) of this subpart one year after the publication date of the final amendments on 

[DATE OF PUBLICATION OF THE FINAL RULE IN THE FEDERAL REGISTER], and the

pressure relief device monitoring requirements of § 63.691(c)(3)(i) and (ii) of this subpart three

years after the publication date of the final amendments on [DATE OF PUBLICATION OF THE 

FINAL RULE IN THE FEDERAL REGISTER].(2) New sources. The owner or operator of an 

affected source for which construction or reconstruction commences on or after October 13, 

1994, must achieve compliance with the provisions of this subpart (except §§ 63.685(b)(2), 

63.691(b)(2), and 63.691(c)(i) and (ii) of this subpart) on or before July 1, 1996, or upon initial 

startup of operations, whichever date is later as provided in 40 CFR 63.6(b). New affected 

sources that commenced construction or reconstruction after October 13, 1994, but on or before 

July 2, 2014, shall be in compliance with the tank requirements of § 63.685(b)(2) of this subpart

two years after the publication date of the final amendments, the equipment leak requirements of 

§ 63.691(b)(2) of this subpart one after the publication date of the final amendments, and the 

pressure relief device monitoring requirements of §63.691(c)(3)(i) and (ii) of this subpart three

years after the effective date of the final amendments. New affected sources that commence 

construction or reconstruction after July 2, 2014, shall be in compliance with the tank

requirements of § 63.685(b)(2) of this subpart, the equipment leak requirements of §

63.691(b)(2) of this subpart, and the pressure relief device monitoring requirements of §

63.691(c)(3)(i) and (ii) of this subpart upon initial startup or by the effective date of the final 

amendments, whichever is later.

(f) The provisions of 40 CFR part 63, subpart A—General Provisions that apply and 

those that do not apply to this subpart are specified in Table 2 of this subpart. 

(g) Applicability of this subpart. (1) The emission limitations set forth in this subpart and 

the emission limitations referred to in this subpart shall apply at all times except during periods 

of non-operation of the affected source (or specific portion thereof) resulting in cessation of the 

emissions to which this subpart applies.

(2) The owner or operator shall not shut down items of equipment that are required or 

utilized for compliance with this subpart during times when emissions are being routed to such 

items of equipment, if the shutdown would contravene requirements of this subpart applicable to 

such items of equipment.

§63.681 Definitions.

All terms used in this subpart shall have the meaning given to them in this section, 40 CFR 63.2 

of this part, and the Act. 

Boiler means an enclosed combustion device that extracts useful energy in the form of steam and 

is not an incinerator or a process heater. 

Bypass means diverting a process vent or closed vent system stream to the atmosphere such that 

it does not first pass through an emission control device.
Closed-vent system means a system that is not open to the atmosphere and is composed of hardpiping, ductwork, connections, and, if necessary, fans, blowers, or other flow-inducing devices 

that conveys gas or vapor from an emission point to a control device. 

Closure device means a cap, hatch, lid, plug, seal, valve, or other type of fitting that prevents or 

reduces air pollutant emissions to the atmosphere by blocking an opening in a cover when the 

device is secured in the closed position. Closure devices include devices that are detachable from 

the cover (e.g., a sampling port cap), manually operated (e.g., a hinged access lid or hatch), or 

automatically operated (e.g., a spring-loaded pressure relief valve). 

Container means a portable unit used to hold material. Examples of containers include but are 

not limited to drums, dumpsters, roll-off boxes, bulk cargo containers commonly known as 

“portable tanks” or “totes”, cargo tank trucks, and tank rail cars. 

Continuous record means documentation of data values measured at least once every 15 minutes 

and recorded at the frequency specified in this subpart.

Continuous recorder means a data recording device that either records an instantaneous data 

value at least once every 15 minutes or records 15-minutes or more frequent block averages. 

Continuous seal means a seal that forms a continuous closure that completely covers the space 

between the edge of the floating roof and the wall of a tank. A continuous seal may be a vapormounted seal, liquid-mounted seal, or metallic shoe seal. A continuous seal may be constructed 

of fastened segments so as to form a continuous seal. 

Control device means equipment used for recovering, removing, oxidizing, or destroying organic 

vapors. Examples of such equipment include but are not limited to carbon adsorbers, condensers, 

vapor incinerators, flares, boilers, and process heaters.

Cover means a device or system that provides a continuous barrier over the material managed in 

an off-site material management unit to prevent or reduce air pollutant emissions to the 

atmosphere. A cover may have openings needed for operation, inspection, sampling, 

maintenance, and repair of the unit provided that each opening is closed when not in use (e.g., 

access hatches, sampling ports). A cover may be a separate piece of equipment which can be 

detached and removed from the unit or a cover may be formed by structural features permanently 

integrated into the design of the unit.

Emission point means an individual tank, surface impoundment, container, oil-water or organicwater separator, transfer system, process vent, or enclosure. 

Enclosure means a structure that surrounds a tank or container, captures organic vapors emitted 

from the tank or container, and vents the captured vapor through a closed vent system to a 

control device. 

External floating roof means a pontoon-type or double-deck type cover that rests on the liquid 

surface in a tank with no fixed roof. 
Fixed roof means a cover that is mounted on a unit in a stationary position and does not move 

with fluctuations in the level of the liquid managed in the unit. 

Flame zone means the portion of the combustion chamber in a boiler or process heater occupied 

by the flame envelope. 

Floating roof means a cover consisting of a double deck, pontoon single deck, or internal 

floating cover which rests upon and is supported by the liquid being contained, and is equipped 

with a continuous seal. 

Flow indicator means a device that indicates whether gas is flowing, or whether the valve 

position would allow gas to flow in a bypass line.

Hard-piping means pipe or tubing that is manufactured and properly installed in accordance with 

relevant standards and good engineering practices. 

Hazardous air pollutants or HAP means the specific organic chemical compounds, isomers, and 

mixtures listed in Table 1 of this subpart.

Hazardous waste means a waste that is determined to be hazardous under the Resource 

Conservation and Recovery Act (PL 94-580) (RCRA), as implemented by 40 CFR parts 260 and 

261.

In gas/vapor service means that a piece of equipment in off-site material service contains or 

contacts a gas or vapor at operating conditions.

In heavy liquid service means that a piece of equipment in off-site material service is not in 

gas/vapor service or in light liquid service.

In light liquid service means that a piece of equipment in off-site material service contains or 

contacts a liquid that meets the following conditions:

(1) The vapor pressure of one or more of the organic compounds is greater than 0.3 kilopascals at 

20 °C,

(2) The total concentration of the pure organic compounds constituents having a vapor pressure 

greater than 0.3 kilopascals at 20 °C is equal to or greater than 20 percent by weight of the total 

process stream, and

(3) The fluid is a liquid at operating conditions.

NOTE: Vapor pressures may be determined by the methods described in 40 CFR 60.485(e)(1).

In liquid service means that a piece of equipment in off-site material service is not in gas/vapor 

service.
Individual drain system means a stationary system used to convey wastewater streams or 

residuals to a waste management unit or to discharge or disposal. The term includes hard-piping, 

all drains and junction boxes, together with their associated sewer lines and other junction boxes 

(e.g., manholes, sumps, and lift stations) conveying wastewater streams or residuals. For the 

purpose of this subpart, an individual drain system is not a drain and collection system that is 

designed and operated for the sole purpose of collecting rainfall runoff (e.g., stormwater sewer 

system) and is segregated from all other individual drain systems.

Internal floating roof means a cover that rests or floats on the liquid surface (but not necessarily 

in complete contact with it inside a tank that has a fixed roof).

Light-material service means the container is used to manage an off-site material for which both 

of the following conditions apply: the vapor pressure of one or more of the organic constituents 

in the off-site material is greater than 0.3 kilopascals (kPa) at 20 °C; and the total concentration 

of the pure organic constituents having a vapor pressure greater than 0.3 kPa at 20 °C is equal to 

or greater than 20 percent by weight.

Liquid-mounted seal means a foam- or liquid-filled continuous seal mounted in contact with the 

liquid in a unit.

Maximum HAP vapor pressure means the sum of the individual HAP equilibrium partial 

pressure exerted by an off-site material at the temperature equal to either: the local maximum 

monthly average temperature as reported by the National Weather Service when the off-site 

material is stored or treated at ambient temperature; or the highest calendar-month average 

temperature of the off-site material when the off-site material is stored at temperatures above the 

ambient temperature or when the off-site material is stored or treated at temperatures below the 

ambient temperature. For the purpose of this subpart, maximum HAP vapor pressure is 

determined using the procedures specified in §63.694(j) of this subpart.

Metallic shoe seal means a continuous seal that is constructed of metal sheets which are held 

vertically against the wall of the tank by springs, weighted levers, or other mechanisms and is 

connected to the floating roof by braces or other means. A flexible coated fabric (envelope) 

spans the annular space between the metal sheet and the floating roof.

No detectable organic emissions means no escape of organics to the atmosphere as determined 

using the procedure specified in §63.694(k) of this subpart.

Off-site material means a material that meets all of the criteria specified in paragraph 

§63.680(b)(1) of this subpart but is not one of the materials specified in §63.680(b)(2) of this 

subpart.

Off-site material management unit means a tank, container, surface impoundment, oil-water 

separator, organic-water separator, or transfer system used to manage off-site material. 
Off-site material service means any time when a pump, compressor, agitator, pressure relief 

device, sampling connection system, open-ended valve or line, valve, connector, or 

instrumentation system contains or contacts off-site material.

Off-site material stream means an off-site material produced or generated by a particular process 

or source such that the composition and form of the material comprising the stream remain 

consistent. An off-site material stream may be delivered, transferred, or otherwise moved to the 

plant site in a continuous flow of material (e.g., wastewater flowing through a pipeline) or in a 

series of discrete batches of material (e.g., a truckload of drums all containing the same off-site 

material or multiple bulk truck loads of an off-site material produced by the same process). 

Oil-water separator means a separator as defined for this subpart that is used to separate oil from 

water. 

Operating parameter value means a minimum or maximum value established for a control 

device or treatment process parameter which, if achieved by itself or in combination with one or 

more other operating parameter values, determines that an owner or operator has complied with 

an applicable emission limitation or standard. 

Organic-water separator means a separator as defined for this subpart that is used to separate 

organics from water. 

Plant site means all contiguous or adjoining property that is under common control including 

properties that are separated only by a road or other public right-of-way. Common control 

includes properties that are owned, leased, or operated by the same entity, parent entity, 

subsidiary, or any combination thereof. A unit or group of units within a contiguous property that 

are not under common control (e.g., a wastewater treatment unit or solvent recovery unit located 

at the site but is sold to a different company) is a different plant site. 

Point-of-delivery means the point at the boundary or within the plant site where the owner or 

operator first accepts custody, takes possession, or assumes responsibility for the management of 

an off-site material stream managed in a waste management operation or recovery operation 

specified in §63.680 (a)(2)(i) through (a)(2)(vi) of this subpart. The characteristics of an off-site 

material stream are determined prior to combining the off-site material stream with other off-site 

material streams or with any other materials. 

Point-of-treatment means a point after the treated material exits the treatment process but before 

the first point downstream of the treatment process exit where the organic constituents in the 

treated material have the potential to volatilize and be released to the atmosphere. For the 

purpose of applying this definition to this subpart, the first point downstream of the treatment 

process exit is not a fugitive emission point due to an equipment leak from any of the following 

equipment components: pumps, compressors, valves, connectors, instrumentation systems, or 

pressure relief devices.
Pressure release means the emission of materials resulting from the system pressure being 

greater than the set pressure of the pressure relief device. This release can be one release or a 

series of releases over a short time period.

Pressure relief device or valve means a safety device used to prevent operating pressures from 

exceeding the maximum allowable working pressure of the process equipment. A common 

pressure relief device is a spring-loaded pressure relief valve. Devices that are actuated either by

a pressure of less than or equal to 2.5 pounds per square inch gauge or by a vacuum are not 

pressure relief devices.

Process heater means an enclosed combustion device that transfers heat released by burning fuel 

directly to process streams or to heat transfer liquids other than water. 

Process vent means an open-ended pipe, stack, or duct through which a gas stream containing 

HAP is continuously or intermittently discharged to the atmosphere from any of the processes 

listed in §63.680(c)(2)(i) through (vi) of this subpart. For the purpose of this subpart, a process 

vent is none of the following: a pressure relief device; an open-ended line or other vent that is 

subject to the equipment leak control requirements under §63.691 of this subpart; or a stack or 

other vent that is used to exhaust combustion products from a boiler, furnace, process heater, 

incinerator, or other combustion device.

Recovery operation means the collection of off-site material management units, process vents, 

and equipment components used at a plant site to manage an off-site material stream from the 

point-of-delivery through the point where the material has been recycled, reprocessed, or rerefined to obtain the intended product or to remove the physical and chemical impurities of 

concern. 

Separator means a waste management unit, generally a tank, used to separate oil or organics 

from water. A separator consists of not only the separation unit but also the forebay and other 

separator basins, skimmers, weirs, grit chambers, sludge hoppers, and bar screens that are located 

directly after the individual drain system and prior to any additional treatment units such as an air 

flotation unit clarifier or biological treatment unit. Examples of a separator include, but are not 

limited to, an API separator, parallel-plate interceptor, and corrugated-plate interceptor with the 

associated ancillary equipment. 

Single-seal system means a floating roof having one continuous seal. This seal may be vapormounted, liquid-mounted, or a metallic shoe seal. 

Surface impoundment means a unit that is a natural topographical depression, man-made 

excavation, or diked area formed primarily of earthen materials (although it may be lined with 

man-made materials), which is designed to hold an accumulation of liquids. Examples of surface 

impoundments include holding, storage, settling, and aeration pits, ponds, and lagoons. 
Tank means a stationary unit that is constructed primarily of nonearthen materials (such as wood, 

concrete, steel, fiberglass, or plastic) which provide structural support and is designed to hold an 

accumulation of liquids or other materials. 

Transfer system means a stationary system for which the predominant function is to convey

liquids or solid materials from one point to another point within a waste management operation 

or recovery operation. For the purpose of this subpart, the conveyance of material using a 

container (as defined for this subpart) or a self-propelled vehicle (e.g., a front-end loader) is not a 

transfer system. Examples of a transfer system include but are not limited to a pipeline, an 

individual drain system, a gravity-operated conveyor (such as a chute), and a mechanicallypowered conveyor (such as a belt or screw conveyor).

Temperature monitoring device means a piece of equipment used to monitor temperature and 

having an accuracy of ±1 percent of the temperature being monitored expressed in degrees 

Celsius (°C) or ±1.2 degrees °C, whichever value is greater. 

Treatment process means a process in which an off-site material stream is physically, 

chemically, thermally, or biologically treated to destroy, degrade, or remove hazardous air 

pollutants contained in the off-site material. A treatment process can be composed of a single 

unit (e.g., a steam stripper) or a series of units (e.g., a wastewater treatment system). A treatment 

process can be used to treat one or more off-site material streams at the same time. 

Used oil means any oil refined from crude oil or any synthetic oil that has been used and as a 

result of such use is contaminated by physical or chemical impurities. This definition is the same 

definition of “used oil” in 40 CFR 279.1. 

Used solvent means a mixture of aliphatic hydrocarbons or a mixture of one and two ring 

aromatic hydrocarbons that has been used as a solvent and as a result of such use is contaminated 

by physical or chemical impurities.

Vapor-mounted seal means a continuous seal that is mounted such that there is a vapor space 

between the liquid in the unit and the bottom of the seal. 

Volatile organic hazardous air pollutant concentration or VOHAP concentration means the 

fraction by weight of those compounds listed in Table 1 of this subpart that are in an off-site 

material as measured using Method 305 in appendix A of this part and expressed in terms of 

parts per million (ppm). As an alternative to using Method 305, an owner or operator may

determine the HAP concentration of an off-site material using any one of the other test methods 

specified in §63.694(b)(2)(ii) of this subpart. When a test method specified in §63.694(b)(2)(ii) 

of this subpart other than Method 305 is used to determine the speciated HAP concentration of 

an off-site material, the individual compound concentration may be adjusted by the 

corresponding fm305 value listed in Table 1 of this subpart to determine a VOHAP concentration.

Waste means a material generated from industrial, commercial, mining, or agricultural operations 

or from community activities that is discarded, discharged, or is being accumulated, stored, or 

physically, chemically, thermally, or biologically treated prior to being discarded or discharged. 
Waste management operation means the collection of off-site material management units, 

process vents, and equipment components used at a plant site to manage an off-site material 

stream from the point-of-delivery to the point where the waste exits or is discharged from the 

plant site or the waste is placed for on-site disposal in a unit not subject to this subpart (e.g., a 

waste incinerator, a land disposal unit). 

Waste stabilization process means any physical or chemical process used to either reduce the 

mobility of hazardous constituents in a waste or eliminate free liquids as determined by Test 

Method 9095—Paint Filter Liquids Test in “Test Methods for Evaluating Solid Waste, 

Physical/Chemical Methods,” EPA Publication No. SW-846, Third Edition, September 1986, as 

amended by Update I, November 15, 1992. (As an alternative, an owner or operator may use any 

more recent, updated version of Method 9095 approved by the EPA.) A waste stabilization 

process includes mixing the waste with binders or other materials and curing the resulting waste 

and binder mixture. Other synonymous terms used to refer to this process are “waste fixation” or 

“waste solidification.” A waste stabilization process does not include the adding of absorbent

materials to the surface of a waste, without mixing, agitation, or subsequent curing, to absorb 

free liquid.

§63.682 [Reserved]

§63.683 Standards: General.

(a) The general standards under this section apply to owners and operators of affected sources as 

designated in §63.680(c) of this subpart.

(b) Off-site material management units. (1) For each off-site material management unit that is 

part of an affected source, the owner or operator must meet the requirements in either paragraph 

(b)(1)(i), (b)(1)(ii), or (b)(1)(iii) of this section except for those off-site material management 

units exempted under paragraph (b)(2) of this section.

(i) The owner or operator controls air emissions from the off-site material management unit in 

accordance with the applicable standards specified in §§63.685 through 63.689 of this subpart.

(ii) The owner or operator removes or destroys HAP in the off-site material before placing the 

material in the off-site material management unit by treating the material in accordance with the 

standards specified in §63.684 of this subpart.

(iii) The owner or operator determines before placing off-site material in the off-site material 

management unit that the average VOHAP concentration of the off-site material is less than 500 

parts per million by weight (ppmw) at the point-of-delivery. The owner or operator must perform 

an initial determination of the average VOHAP concentration of the off-site material using the 

procedures specified in §63.694(b) of this subpart. This initial determination must be performed 

either before the first time any portion of the off-site material stream is placed in the unit or by

the compliance date, whichever date is later. Thereafter, the owner or operator must review and 
update, as necessary, this determination at least once every calendar year following the date of 

the initial determination for the off-site material stream.

(2) An off-site material management unit is exempted from the requirements in paragraph (b)(1) 

of this section when the owner or operator meets one of the exemptions provided in paragraphs 

(b)(2)(i) through (b)(2)(iv) of this section as applicable to the unit.

(i) An off-site material management unit is exempted from the requirements in paragraph (b)(1) 

of this section if the off-site material management unit is also subject to another subpart under 40 

CFR part 63 or 40 CFR part 61, and the owner or operator is controlling the HAP listed in Table 

1 of this subpart that are emitted from the unit in compliance with the provisions specified in the 

other applicable subpart under part 61 or part 63.

(ii) At the discretion of the owner or operator, one or a combination of off-site material 

management units may be exempted from the requirements in paragraph (b)(1) of this section 

when these units meet the condition that the total annual quantity of HAP contained in the offsite material placed in the units exempted under this paragraph (b)(2)(ii) is less than 1 megagram 

per year. For the off-site material management units selected by the owner or operator to be 

exempted from the requirements in paragraph (b)(1) of this section, the owner or operator must 

meet the requirements in paragraphs (b)(2)(ii)(A) and (b)(2)(ii)(B) of this section. An owner or 

operator may change the off-site material management units selected to be exempted under this 

paragraph (b)(2)(ii) by preparing a new designation for the exempt-units as required by 

paragraph (b)(2)(ii)(A) of this section and performing a new determination as required by

paragraph (b)(2)(ii)(B) of this section.

(A) The owner or operator must designate each of the off-site material management units 

selected by the owner or operator to be exempt under paragraph (b)(2)(ii) of this section by either 

submitting to the Administrator a written notification identifying the exempt-units or 

permanently marking the exempt-units at the plant site. If an owner or operator chooses to 

prepare and submit a written notification, this notification must include a site plan, process 

diagram, or other appropriate documentation identifying each of the exempt-units. If an owner or 

operator chooses to permanently mark the exempt-units, each exempt-unit must be marked in 

such a manner that it can be readily identified as an exempt-unit from the other off-site material 

management units located at the plant site.

(B) The owner or operator must prepare an initial determination of the total annual HAP quantity

in the off-site material placed in the units exempted under this paragraph (b)(2)(ii). This 

determination is based on the total quantity of the HAP listed in Table 1 of this subpart as 

determined at the point where the off-site material is placed in each exempted unit. The owner or 

operator must perform a new determination whenever the extent of changes to the quantity or 

composition of the off-site material placed in the exempted units could cause the total annual 

HAP content in the off-site material to exceed 1 megagram per year. The owner or operator must 

maintain documentation to support the most recent determination of the total annual HAP 

quantity. This documentation must include the basis and data used for determining the HAP 

content of the off-site material.
(iii) A tank or surface impoundment is exempted from the requirements in paragraph (b)(1) of 

this section if the unit is used for a biological treatment process that meets the requirements in 

either paragraph (b)(2)(iii)(A) or (b)(2)(iii)(B) of this section and the owner or operator complies 

with the monitoring requirements in §63.684(e)(4) of this subpart.

(A) The HAP biodegradation efficiency (Rbio) for the biological treatment process is equal to or 

greater than 95 percent. The HAP biodegradation efficiency (Rbio) shall be determined in 

accordance with the requirements of §63.694(h) of this subpart.

(B) The total actual HAP mass removal rate (MRbio) for the off-site material treated by the 

biological treatment process is equal to or greater than the required HAP mass removal rate 

(RMR) for the off-site material. The total actual HAP mass removal rate (MRbio) must be 

determined in accordance with the requirements of §63.694(i) of this subpart. The required HAP 

mass removal rate (RMR) must be determined in accordance with the requirements of §63.694(e) 

of this subpart.

(iv) An off-site material management unit is exempted from the requirements in paragraph (b)(1) 

of this section if the off-site material placed in the unit is a hazardous waste that meets the 

conditions specified in either paragraph (b)(2)(iv)(A) or (b)(2)(iv)(B) of this section.

(A) The hazardous waste meets the numerical organic concentration limits, applicable to the 

hazardous waste, as specified in 40 CFR part 268—Land Disposal Restrictions, listed in the 

table, “Treatment Standards for Hazardous Waste” in 40 CFR 268.40.

(B) The organic hazardous constituents in the hazardous waste have been treated by the 

treatment technology established by the EPA for the hazardous waste in 40 CFR 268.42(a), or 

have been removed or destroyed by an equivalent method of treatment approved by the EPA 

under 40 CFR 268.42(b).

(v) A tank used for bulk feed of off-site material to a waste incinerator is exempted from the 

requirements specified in paragraph (b)(1) of this section if the tank meets all of the conditions 

specified in paragraphs (b)(2)(v)(A) through (b)(2)(v)(C) of this section.

(A) The tank is located inside an enclosure vented to a control device that is designed and 

operated in accordance with all applicable requirements specified under 40 CFR part 61, subpart 

FF—National Emission Standards for Benzene Waste Operations for a facility at which the total 

annual benzene quantity from the facility waste is equal to or greater than 10 megagrams per 

year;

(B) The enclosure and control device serving the tank were installed and began operation prior to 

July 1, 1996; and

(C) The enclosure is designed and operated in accordance with the criteria for a permanent total 

enclosure as specified in “Procedure T—Criteria for and Verification of a Permanent or 

Temporary Total Enclosure” under 40 CFR 52.741, appendix B. The enclosure may have 

permanent or temporary openings to allow worker access; passage of material into or out of the 
enclosure by conveyor, vehicles, or other mechanical or electrical equipment; or to direct air 

flow into the enclosure. The owner or operator must annually perform the verification procedure 

for the enclosure as specified in Section 5.0 to “Procedure T—Criteria for and Verification of a 

Permanent or Temporary Total Enclosure.”

(c) Process vents. (1) For each process vent that is part of an affected source, the owner or 

operator must meet the requirements in either paragraph (c)(1)(i) or (c)(1)(ii) of this section 

except for those process vents exempted under paragraph (c)(2) of this section.

(i) The owner or operator controls air emissions from the process vent in accordance with the 

standards specified in §63.690 of this subpart.

(ii) The owner or operator determines before placing off-site material in the process equipment 

associated with the process vent that the average VOHAP concentration of the off-site material is 

less than 500 ppmw at the point-of-delivery. The owner or operator must perform an initial 

determination of the average VOHAP concentration of the off-site material using the procedures 

specified in §63.694(b) of this subpart before any portion of the off-site material stream is placed 

in the unit. Thereafter, the owner or operator must review and update, as necessary, this 

determination at least once every calendar year following the date of the initial determination for 

the off-site material stream.

(2) A process vent is exempted from the requirements of paragraph (c)(1) of this section when 

the owner or operator meets one of the exemptions provided in paragraphs (c)(2)(i) through 

(c)(2)(iii) of this section.

(i) A process vent is exempted from the requirements in paragraph (c)(1) of this section if the 

process vent is also subject to another subpart under part 63 or 40 CFR part 61, and the owner or 

operator is controlling the HAP listed in Table 1 of this subpart that are emitted from the process 

vent in compliance with the provisions specified in the other applicable subpart under part 61 or 

part 63.

(ii) A process vent is exempted from the requirements specified in paragraph (c)(1) of this 

section if the owner or operator determines that the process vent stream flow rate is less than 

0.005 cubic meters per minute (m3/min) at standard conditions (as defined in 40 CFR 63.2). The 

process vent stream flow rate shall be determined in accordance with the procedures specified in 

§63.694(m) of this subpart. Documentation must be prepared by the owner or operator and 

maintained at the plant site to support the determination of the process vent stream flow rate. 

This documentation must include identification of each process vent exempted under this 

paragraph and the test results used to determine the process vent stream flow rate.

(iii) A process vent is exempted from the requirements specified in paragraph (c)(1) of this 

section if the owner or operator determines that the process vent stream flow rate is less than 6.0 

m

3

/min at standard conditions (as defined in 40 CFR 63.2) and the total HAP concentration is 

less than 20 ppmv. The process vent stream flow rate and total HAP concentration shall be 

determined in accordance with the procedures specified in §63.694(m) of this subpart. 

Documentation must be prepared by the owner or operator and maintained at the plant site to 
support the determination of the process vent stream flow rate and total HAP concentration. This 

documentation must include identification of each process vent exempted under this paragraph 

(c)(2)(iii) and the test results used to determine the process vent stream flow rate and total HAP 

concentration. The owner or operator must perform a new determination of the process vent 

stream flow rate and total HAP concentration when the extent of changes to operation of the unit 

on which the process vent is used could cause either the process vent stream flow rate to exceed 

the limit of 6.0 m3/min or the total HAP concentration to exceed the limit of 20 ppmv.

(d) Equipment leaks. The owner or operator must control equipment leaks from each equipment 

component that is part of the affected source specified in §63.680(c)(3) of this subpart by

implementing leak detection and control measures in accordance with the standards specified in 

§63.691 of this subpart.

(e) General Duty. At all times, the owner or operator must operate and maintain any affected 

source, including associated air pollution control equipment and monitoring equipment, in a 

manner consistent with safety and good air pollution control practices for minimizing emissions. 

The general duty to minimize emissions does not require the owner operator to make any further 

efforts to reduce emissions if levels required by the applicable standard have been achieved. 

Determination of whether a source is operating in compliance with operation and maintenance 

requirements will be based on information available to the Administrator, which may include, 

but is not limited to, monitoring results, review of operation and maintenance procedures, review 

of operation and maintenance records, and inspection of the source.

(f) In addition to the cases listed in § 63.695(e)(4) of this subpart, deviation means any of the 

cases listed in paragraphs (f)(1) through (6) of this section.

(1) Any instance in which an affected source subject to this subpart, or an owner or operator of 

such a source, fails to meet any requirement or obligation established by this subpart, including, 

but not limited to, any emission limit, operating limit or work practice standard.

(2) When a performance test indicates that emissions of a pollutant in Table 1 to this subpart are 

exceeding the emission standard for the pollutant specified in Table 1 to this subpart.

(3) When the average value of a monitored operating parameter, based on the data averaging 

period for compliance specified in § 63.695 of this subpart, does not meet the operating limit 

specified in § 63.693 of this subpart.

(4) When an affected source discharges directly into the atmosphere from any of the sources 

specified in paragraphs (f)(4)(i) and (ii) of this section.

(i) A pressure relief device, as defined in § 63.681 of this subpart.

(ii) A bypass, as defined in § 63.681 of this subpart.
(5) Any instance in which the affected source subject to this subpart, or an owner or operator of 

such a source, fails to meet any term or condition specified in paragraph (f)(5)(i) or (ii) of this 

section.

(i) Any term or condition that is adopted to implement an applicable requirement in this subpart.

(ii) Any term or condition relating to compliance with this subpart that is included in the 

operating permit for an affected source to obtain such a permit.

(6) Any failure to collect required data, except for periods of monitoring system malfunctions, 

repairs associated with monitoring system malfunctions, and required monitoring system quality 

assurance or quality control activities (including, as applicable, calibration checks and required 

zero and span adjustments).

§63.684 Standards: Off-site material treatment.

(a) The provisions of this section apply to the treatment of off-site material to remove or destroy

HAP for which §63.683(b)(1)(ii) of this subpart references the requirements of this section for 

such treatment.

(b) The owner or operator shall remove or destroy the HAP contained in off-site material streams 

to be managed in the off-site material management unit in accordance with §63.683(b)(1)(ii) of 

this subpart using a treatment process that continuously achieves, under normal operations, one 

or more of the performance levels specified in paragraphs (b)(1) through (b)(5) of this section (as 

applicable to the type of treatment process) for the range of off-site material stream compositions 

and quantities expected to be treated.

(1) VOHAP concentration. The treatment process shall reduce the VOHAP concentration of the 

off-site material using a means, other than by dilution, to achieve one of the following 

performance levels, as applicable: 

(i) In the case when every off-site material stream entering the treatment process has an average 

VOHAP concentration equal to or greater than 500 ppmw at the point-of-delivery, then the 

VOHAP concentration of the off-site material shall be reduced to a level that is less than 500 

ppmw at the point-of-treatment. 

(ii) In the case when off-site material streams entering the treatment process are a mixture of offsite material streams having an average VOHAP concentration equal to or greater than 500 

ppmw at the point-of-delivery with off-site material streams having average VOHAP 

concentrations less than 500 ppmw at the point-of-delivery, then the VOHAP concentration of 

the off-site material must be reduced to a level at the point-of-treatment that meets the 

performance level specified in either paragraph (b)(1)(ii)(A) or (B) of this section.

(A) Less than the VOHAP concentration limit (CR) established for the treatment process using 

the procedure specified in §63.694(d); or
(B) Less than the lowest VOHAP concentration determined for each of the off-site material 

streams entering the treatment process as determined by the VOHAP concentration of the off-site 

material at the point-of-delivery.

(2) HAP mass removal. The treatment process shall achieve a performance level such that the 

total quantity of HAP actually removed from the off-site material stream (MR) is equal to or 

greater than the required mass removal (RMR) established for the off-site material stream using 

the procedure specified in §63.694(e) of this subpart. The MR for the off-site material streams 

shall be determined using the procedures specified in §63.694(f) of this subpart. 

(3) HAP reduction efficiency. For any treatment process except a treatment process that uses 

biological degradation and is performed in an open tank or surface impoundment, the treatment 

process must achieve the applicable performance level specified in either paragraph (b)(3)(i) or 

(b)(3)(ii) of this section.

(i) In the case when the owner or operator determines that off-site material stream entering the 

treatment process has an average VOHAP concentration less than 10,000 ppmw at the point-ofdelivery, then the treatment process shall achieve a performance level such that the total quantity

of HAP in the off-site material stream is reduced by 95 percent or more. The HAP reduction 

efficiency (R) for the treatment process shall be determined using the procedure specified in 

§63.694(g) of this subpart. The average VOHAP concentration of the off-site material stream at 

the point-of-delivery shall be determined using the procedure specified in §63.694(b) of this 

subpart. 

(ii) In the case when the off-site material stream entering the treatment process has an average 

VOHAP concentration equal to or greater than 10,000 ppmw at the point-of-delivery, then the 

treatment process shall achieve a performance level such that the total quantity of HAP in the 

off-site material stream is reduced by 95 percent or more, and the average VOHAP concentration 

of the off-site material at the point-of-treatment is less than 100 parts per million by weight 

(ppmw). The HAP reduction efficiency (R) for the treatment process shall be determined using 

the procedure specified in §63.694(g) of this subpart. The average VOHAP concentration of the 

off-site material stream at the point-of-treatment shall be determined using the procedure 

specified in §63.694(c) of this subpart. 

(4) Biological degradation performed in an open tank or surface impoundment. A treatment 

process using biological degradation and performed in an open tank or surface impoundment 

must achieve the performance level specified in either paragraph (b)(4)(i) or (b)(4)(ii) of this 

section.

(i) The HAP reduction efficiency (R) for the treatment process is equal to or greater than 95 

percent, and the HAP biodegradation efficiency (Rbio) for the treatment process is equal to or 

greater than 95 percent. The HAP reduction efficiency (R) shall be determined using the 

procedure specified in §63.694(g) of this subpart. The HAP biodegradation efficiency (Rbio) shall 

be determined in accordance with the requirements of §63.694(h) of this subpart. 
(ii) The total quantity of HAP actually removed from the off-site material stream by biological 

degradation (MRbio) shall be equal to or greater than the required mass removal (RMR) 

established for the off-site material stream using the procedure specified in §63.694(e) of this 

subpart. The MRbio of the off-site material stream shall be determined using the procedures 

specified in §63.694(i) of this subpart. 

(5) Incineration. The treatment process must destroy the HAP contained in the off-site material 

stream using one of the combustion devices specified in paragraphs (b)(5)(i) through (b)(5)(v) of 

this section.

(i) An incinerator for which the owner or operator has been issued a final permit under 40 CFR 

part 270, and the incinerator is designed and operated in accordance with the requirements of 40 

CFR part 264, subpart O—Incinerators, or

(ii) An incinerator for which the owner or operator has certified compliance with the interim 

status requirements of 40 CFR part 265, subpart O—Incinerators.

(iii) A boiler or industrial furnace for which the owner or operator has been issued a final permit 

under 40 CFR part 270, and the combustion unit is designed and operated in accordance with the 

requirements of 40 CFR part 266, subpart H—Hazardous Waste Burned in Boilers and Industrial 

Furnaces.

(iv) A boiler or industrial furnace for which the owner or operator has certified compliance with 

the interim status requirements of 40 CFR part 266, subpart H Hazardous Waste Burned in 

Boilers and Industrial Furnaces.

(v) An incinerator, boiler, or industrial furnace for which the owner or operator has submitted a 

Notification of Compliance under 40 CFR 63.1207(j) and 63.1210(d) and complies with the 

requirements of 40 CFR part 63, subpart EEE at all times (including times when non-hazardous 

waste is being burned).

(c) For a treatment process that removes the HAP from the off-site material by a means other 

than thermal destruction or biological degradation to achieve one of the performances levels 

specified in paragraph (b)(1), (b)(2), or (b)(3) of this section, the owner or operator shall manage 

the HAP removed from the off-site material in such a manner to minimize release of these HAP 

to the atmosphere, to the extent practical. Examples of HAP emission control measures that meet 

the requirements of this paragraph include managing the HAP removed from the off-site material 

in units that use air emission controls in accordance with the standards specified in §§63.685 

through 63.689 of this subpart, as applicable to the unit. 

(d) When the owner or operator treats the off-site material to meet one of the performance levels 

specified in paragraphs (b)(1) through (b)(4) of this section, the owner or operator shall 

demonstrate that the treatment process achieves the selected performance level for the range of 

expected off-site material stream compositions expected to be treated. An initial demonstration 

shall be performed as soon as possible but no later than 30 days after first time an owner or 

operator begins using the treatment process to manage off-site material streams in accordance 
with the requirements of either §63.683(b)(1)(ii) or §63.683(b)(2)(ii) of this subpart as applicable 

to the affected off-site material management unit or process equipment. Thereafter, the owner or 

operator shall review and update, as necessary, this demonstration at least once every calendar 

year following the date of the initial demonstration.

(e) When the owner or operator treats the off-site material to meet one of the performance levels 

specified in paragraphs (b)(1) through (b)(4) of this section, the owner or operator shall ensure 

that the treatment process is achieving the applicable performance requirements by continuously 

monitoring the operation of the process when it is used to treat off-site material by complying 

with paragraphs (e)(1) through (e)(3) or, for biological treatment units, paragraph (e)(4) of this 

section:

(1) A continuous monitoring system shall be installed and operated for each treatment that 

measures operating parameters appropriate for the treatment process technology. This system 

shall include a continuous recorder that records the measured values of the selected operating 

parameters. The monitoring equipment shall be installed, calibrated, and maintained in 

accordance with the equipment manufacturer's specifications. The continuous recorder shall be a 

data recording device that is capable of recording either an instantaneous data value at least once 

every 15 minutes or an average value for intervals of 15 minutes or less.

(2) For each monitored operating parameter, the owner or operator shall establish a minimum 

operating parameter value or a maximum operating parameter value, as appropriate, to define the 

range of conditions at which the treatment process must be operated to continuously achieve the 

applicable performance requirements of this section.

(3) When the treatment process is operating to treat off-site material, the owner or operator shall 

inspect the data recorded by the continuous monitoring system on a routine basis and operate the 

treatment process such that the actual value of each monitored operating parameter is greater 

than the minimum operating parameter value or less than the maximum operating parameter 

value, as appropriate, established for the treatment process.

(4) When the treatment process is a biological treatment process that is complying with 

paragraph (b)(4) of this section, the owner or operator must establish and implement a written 

procedure to monitor the appropriate parameters that demonstrate proper operation of the 

biological treatment unit in accordance with the evaluation required in §63.694(h) of this 

subpart. The written procedure must list the operating parameters that will be monitored and 

state the frequency of monitoring to ensure that the biological treatment unit is operating 

between the minimum operating parameter values and maximum operating parameter values to 

establish that the biological treatment unit is continuously achieving the performance 

requirement.

(f) The owner or operator must maintain records for each treatment process in accordance with 

the requirements of §63.696(a) of this subpart.

(g) The owner or operator must prepare and submit reports for each treatment process in 

accordance with the requirements of §63.697(a) of this subpart.
(h) The Administrator may at any time conduct or require that the owner or operator conduct 

testing necessary to demonstrate that a treatment process is achieving the applicable performance 

requirements of this section. The testing shall be conducted in accordance with the applicable 

requirements of this section. The Administrator may elect to have an authorized representative 

observe testing conducted by the owner or operator. 

§63.685 Standards: Tanks.

(a) The provisions of this section apply to the control of air emissions from tanks for which 

§63.683(b)(1)(i) of this subpart references the use of this section for such air emission control. 

(b) According to the date an affected source commenced construction or reconstruction and the 

date an affected source receives off-site material for the first time as established in § 63.680(e)(i)

through (iii) of this subpart, the owner or operator shall control air emissions from each tank 

subject to this section in accordance with either paragraph (b)(1)(i) or (ii) of this section.

(1) (i) For a tank that is part of an existing affected source but the tank is not used for a waste 

stabilization process as defined in § 63.681 of this subpart, the owner or operator shall determine 

whether the tank is required to use either Tank Level 1 controls or Tank Level 2 controls as 

specified for the tank by Table 3 of this subpart based on the off-site material maximum HAP 

vapor pressure and the tank's design capacity. The owner or operator shall control air emissions 

from a tank required by Table 3 to use Tank Level 1 controls in accordance with the 

requirements of paragraph (c) of this section. The owner or operator shall control air emissions 

from a tank required by Table 3 to use Tank Level 2 controls in accordance with the 

requirements of paragraph (d) of this section.

(ii) For a tank that is part of an existing affected source but the tank is not used for a waste 

stabilization process as defined in § 63.681 of this subpart, the owner or operator shall determine 

whether the tank is required to use either Tank Level 1 controls or Tank Level 2 controls as 

specified for the tank by Table 4 of this subpart based on the off-site material maximum HAP 

vapor pressure and the tank's design capacity. The owner or operator shall control air emissions

from a tank required by Table 4 to use Tank Level 1 controls in accordance with the 

requirements of paragraph (c) of this section. The owner or operator shall control air emissions

from a tank required by Table 4 to use Tank Level 2 controls in accordance with the 

requirements of paragraph (d) of this section.

(2) For a tank that is part of a new affected source but the tank is not used for a waste 

stabilization process as defined in §63.681 of this subpart, the owner or operator shall determine 

whether the tank is required to use either Tank Level 1 controls or Tank Level 2 controls as 

specified for the tank by Table 5 of this subpart based on the off-site material maximum HAP 

vapor pressure and the tank's design capacity. The owner or operator shall control air emissions 

from a tank required by Table 5 to use Tank Level 1 controls in accordance with the 

requirements of paragraph (c) of this section. The owner or operator shall control air emissions 

from a tank required by Table 5 to use Tank Level 2 controls in accordance with the 

requirements of paragraph (d) of this section.
(3) For a tank that is used for a waste stabilization process, the owner or operator shall control 

air emissions from the tank by using Tank Level 2 controls in accordance with the requirements 

of paragraph (d) of this section.

(c) Owners and operators controlling air emissions from a tank using Tank Level 1 controls shall 

meet the following requirements: 

(1) The owner or operator shall determine the maximum HAP vapor pressure for an off-site 

material to be managed in the tank using Tank Level 1 controls before the first time the off-site 

material is placed in the tank. The maximum HAP vapor pressure shall be determined using the 

procedures specified in § 63.694(j) of this subpart. Thereafter, the owner or operator shall 

perform a new determination whenever changes to the off-site material managed in the tank 

could potentially cause the maximum HAP vapor pressure to increase to a level that is equal to 

or greater than the maximum HAP vapor pressure limit for the tank design capacity category 

specified in Table 3, Table 4 or Table 5 of this subpart, as applicable to the tank. 

(2) The owner or operator must control air emissions from the tank in accordance with the 

requirements in either paragraph (c)(2)(i), (c)(2)(ii), or (c)(2)(iii) of this section, as applicable to 

the tank.

(i) The owner or operator controls air emissions from the tank in accordance with the provisions 

specified in subpart OO of 40 CFR part 63—National Emission Standards for Tanks—Level 1, 

except that 40 CFR 63.902(c)(2) and (3) shall not apply for the purposes of this subpart.

(ii) As an alternative to meeting the requirements in paragraph (c)(2)(i) of this section, an owner 

or operator may control air emissions from the tank in accordance with the provisions for Tank 

Level 2 controls as specified in paragraph (d) of this section.

(iii) As an alternative to meeting the requirements in paragraph (c)(2)(i) of this section when a 

tank is used as an interim transfer point to transfer off-site material from containers to another 

off-site material management unit, an owner or operator may control air emissions from the tank 

in accordance with the requirements in paragraphs (c)(2)(iii)(A) and (c)(2)(iii)(B) of this section. 

An example of such a tank is an in-ground tank into which organic-contaminated debris is 

dumped from roll-off boxes or dump trucks, and then this debris is promptly transferred from the 

tank to a macroencapsulation unit by a backhoe.

(A) During those periods of time when the material transfer activity is occurring, the tank may be 

operated without a cover.

(B) At all other times, air emissions from the tank must be controlled in accordance with the 

provisions specified in 40 CFR part 63, subpart OO—National Emission Standards for Tanks—

Level 1, with the exceptions specified in paragraphs (c)(2)(iii)(B)(1) and (2) of this section.

(1) Where 40 CFR 63.902(c)(2) provides an exception for a spring-loaded pressure-vacuum 

relief valve, conservation vent, or similar type of pressure relief device which vents to the 
atmosphere, only a conservation vent shall be eligible for the exception for the purposes of this 

subpart.

(2) 40 CFR 63.902(c)(3) shall not apply for the purposes of this subpart.

(d) Owners and operators controlling air emissions from a tank using Tank Level 2 controls shall 

use one of the following tanks: 

(1) A fixed-roof tank equipped with an internal floating roof in accordance with the requirements 

specified in paragraph (e) of this section; 

(2) A tank equipped with an external floating roof in accordance with the requirements specified 

in paragraph (f) of this section; 

(3) A tank vented through a closed-vent system to a control device in accordance with the 

requirements specified in paragraph (g) of this section; 

(4) A pressure tank designed and operated in accordance with the requirements specified in 

paragraph (h) of this section; or 

(5) A tank located inside an enclosure that is vented through a closed-vent system to an enclosed 

combustion control device in accordance with the requirements specified in paragraph (i) of this 

section. 

(e) The owner or operator who elects to control air emissions from a tank using a fixed-roof with 

an internal floating roof shall meet the requirements specified in paragraphs (e)(1) through (e)(3) 

of this section. 

(1) The tank shall be equipped with a fixed roof and an internal floating roof in accordance with 

the following requirements: 

(i) The internal floating roof shall be designed to float on the liquid surface except when the 

floating roof must be supported by the leg supports. 

(ii) The internal floating roof shall be equipped with a continuous seal between the wall of the 

tank and the floating roof edge that meets either of the following requirements: 

(A) A single continuous seal that is either a liquid-mounted seal or a metallic shoe seal, as 

defined in §63.681 of this subpart; or 

(B) Two continuous seals mounted one above the other. The lower seal may be a vapor-mounted 

seal. 

(iii) The internal floating roof shall meet the following specifications: 
(A) Each opening in a noncontact internal floating roof except for automatic bleeder vents 

(vacuum breaker vents) and the rim space vents is to provide a projection below the liquid 

surface. 

(B) Each opening in the internal floating roof shall be equipped with a gasketed cover or a 

gasketed lid except for leg sleeves, automatic bleeder vents, rim space vents, column wells, 

ladder wells, sample wells, and stub drains. 

(C) Each penetration of the internal floating roof for the purpose of sampling shall have a slit 

fabric cover that covers at least 90 percent of the opening. 

(D) Each automatic bleeder vent and rim space vent shall be gasketed. 

(E) Each penetration of the internal floating roof that allows for passage of a ladder shall have a 

gasketed sliding cover. 

(F) Each penetration of the internal floating roof that allows for passage of a column supporting 

the fixed roof shall have a flexible fabric sleeve seal or a gasketed sliding cover. 

(2) The owner or operator shall operate the tank in accordance with the following requirements:

(i) When the floating roof is resting on the leg supports, the process of filling, emptying, or 

refilling shall be continuous and shall be accomplished as soon as practical. 

(ii) Automatic bleeder vents are to be set closed at all times when the roof is floating, except 

when the roof is being floated off or is being landed on the leg supports. 

(iii) Prior to filling the tank, each cover, access hatch, gauge float well or lid on any opening in 

the internal floating roof shall be bolted or fastened closed (i.e., no visible gaps). Rim spaces 

vents are to be set to open only when the internal floating roof is not floating or when the 

pressure beneath the rim exceeds the manufacturer's recommended setting. 

(3) The owner or operator shall inspect the internal floating roof in accordance with the 

procedures specified in §63.695(b) of this subpart. 

(f) The owner or operator who elects to control tank emissions by using an external floating roof 

shall meet the requirements specified in paragraphs (f)(1) through (f)(3) of this section. 

(1) The owner or operator shall design the external floating roof in accordance with the 

following requirements: 

(i) The external floating roof shall be designed to float on the liquid surface except when the 

floating roof must be supported by the leg supports. 
(ii) The floating roof shall be equipped with two continuous seals, one above the other, between 

the wall of the tank and the roof edge. The lower seal is referred to as the primary seal, and the 

upper seal is referred to as the secondary seal. 

(A) The primary seal shall be a liquid-mounted seal or a metallic shoe seal, as defined in §63.681 

of this subpart. The total area of the gaps between the tank wall and the primary seal shall not 

exceed 212 square centimeters (cm2) per meter of tank diameter, and the width of any portion of 

these gaps shall not exceed 3.8 centimeters (cm). If a metallic shoe seal is used for the primary

seal, the metallic shoe seal shall be designed so that one end extends into the liquid in the tank 

and the other end extends a vertical distance of at least 61 centimeters (24 inches) above the 

liquid surface.

(B) The secondary seal shall be mounted above the primary seal and cover the annular space 

between the floating roof and the wall of the tank. The total area of the gaps between the tank 

wall and the secondary seal shall not exceed 21.2 square centimeters (cm2) per meter of tank 

diameter, and the width of any portion of these gaps shall not exceed 1.3 centimeters (cm). 

(iii) The external floating roof shall be meet the following specifications: 

(A) Except for automatic bleeder vents (vacuum breaker vents) and rim space vents, each 

opening in a noncontact external floating roof shall provide a projection below the liquid surface. 

(B) Except for automatic bleeder vents, rim space vents, roof drains, and leg sleeves, each 

opening in the roof shall be equipped with a gasketed cover, seal, or lid. 

(C) Each access hatch and each gauge float wells shall be equipped with covers designed to be 

bolted or fastened when the cover is secured in the closed position. 

(D) Each automatic bleeder vent and each rim space vents shall be equipped with a gasket. 

(E) Each roof drain that empties into the liquid managed in the tank shall be equipped with a 

slotted membrane fabric cover that covers at least 90 percent of the area of the opening. 

(F) Each unslotted and slotted guide pole well shall be equipped with a gasketed sliding cover or 

a flexible fabric sleeve seal. 

(G) Each unslotted guide pole shall be equipped with a gasketed cap on the end of the pole. 

(H) Each slotted guide pole shall be equipped with a gasketed float or other device which closes 

off the surface from the atmosphere. 

(I) Each gauge hatch and each sample well shall be equipped with a gasketed cover. 

(2) The owner or operator shall operate the tank in accordance with the following requirements:
(i) When the floating roof is resting on the leg supports, the process of filling, emptying, or 

refilling shall be continuous and shall be accomplished as soon as practical. 

(ii) Except for automatic bleeder vents, rim space vents, roof drains, and leg sleeves, each 

opening in the roof shall be secured and maintained in a closed position at all times except when 

the closure device must be open for access. 

(iii) Covers on each access hatch and each gauge float well shall be bolted or fastened when 

secured in the closed position. 

(iv) Automatic bleeder vents shall be set closed at all times when the roof is floating, except 

when the roof is being floated off or is being landed on the leg supports. 

(v) Rim space vents shall be set to open only at those times that the roof is being floated off the 

roof leg supports or when the pressure beneath the rim seal exceeds the manufacturer's 

recommended setting. 

(vi) The cap on the end of each unslotted guide pole shall be secured in the closed position at all 

times except when measuring the level or collecting samples of the liquid in the tank. 

(vii) The cover on each gauge hatch or sample well shall be secured in the closed position at all 

times except when the hatch or well must be opened for access. 

(viii) Both the primary seal and the secondary seal shall completely cover the annular space 

between the external floating roof and the wall of the tank in a continuous fashion except during 

inspections. 

(3) The owner or operator shall inspect the external floating roof in accordance with the 

procedures specified in §63.695(b) of this subpart. 

(g) The owner or operator who controls tank air emissions by venting to a control device shall 

meet the requirements specified in paragraphs (g)(1) through (g)(3) of this section. 

(1) The tank shall be covered by a fixed roof and vented directly through a closed-vent system to 

a control device in accordance with the following requirements: 

(i) The fixed roof and its closure devices shall be designed to form a continuous barrier over the 

entire surface area of the liquid in the tank. 

(ii) Each opening in the fixed roof not vented to the control device shall be equipped with a 

closure device. If the pressure in the vapor headspace underneath the fixed roof is less than 

atmospheric pressure when the control device is operating, the closure devices shall be designed 

to operate such that when the closure device is secured in the closed position there are no visible 

cracks, holes, gaps, or other open spaces in the closure device or between the perimeter of the 

cover opening and the closure device. If the pressure in the vapor headspace underneath the fixed 
roof is equal to or greater than atmospheric pressure when the control device is operating, the 

closure device shall be designed to operate with no detectable organic emissions. 

(iii) The fixed roof and its closure devices shall be made of suitable materials that will minimize 

exposure of the off-site material to the atmosphere, to the extent practical, and will maintain the 

integrity of the equipment throughout its intended service life. Factors to be considered when 

selecting the materials for and designing the fixed roof and closure devices shall include: organic 

vapor permeability, the effects of any contact with the liquid and its vapor managed in the tank; 

the effects of outdoor exposure to wind, moisture, and sunlight; and the operating practices used 

for the tank on which the fixed roof is installed. 

(iv) The closed-vent system and control device shall be designed and operated in accordance 

with the requirements of §63.693 of this subpart. 

(2) Whenever an off-site material is in the tank, the fixed roof shall be installed with each closure 

device secured in the closed position and the vapor headspace underneath the fixed roof vented 

to the control device except that venting to the control device is not required, and opening of 

closure devices or removal of the fixed roof is allowed at the following times: 

(i) To provide access to the tank for performing routine inspection, maintenance, or other 

activities needed for normal operations. Examples of such activities include those times when a 

worker needs to open a port to sample liquid in the tank, or when a worker needs to open a hatch 

to maintain or repair equipment. Following completion of the activity, the owner or operator 

shall promptly secure the closure device in the closed position or reinstall the cover, as 

applicable, to the tank. 

(ii) To remove accumulated sludge or other residues from the bottom of the tank.

(3) The owner or operator shall inspect and monitor the air emission control equipment in 

accordance with the procedures specified in §63.695 of this subpart. 

(h) The owner or operator who elects to control tank air emissions by using a pressure tank shall 

meet the following requirements. 

(1) The tank shall be designed not to vent to the atmosphere as a result of compression of the 

vapor headspace in the tank during filling of the tank to its design capacity. 

(2) All tank openings shall be equipped with closure devices designed to operate with no 

detectable organic emissions as determined using the procedure specified in §63.694(k) of this 

subpart.

(3) Whenever an off-site material is in the tank, the tank shall be operated as a closed system that 

does not vent to the atmosphere except at those times when purging of inerts from the tank is 

required and the purge stream is routed to a closed-vent system and control device designed and 

operated in accordance with the requirements of § 63.693 of this subpart. 
(i) The owner or operator who elects to control air emissions by using an enclosure vented 

through a closed-vent system to an enclosed combustion control device shall meet the 

requirements specified in paragraphs (i)(1) through (3) of this section.

(1) The tank shall be located inside an enclosure. The enclosure shall be designed and operated 

in accordance with the criteria for a permanent total enclosure as specified in “Procedure T—

Criteria for and Verification of a Permanent or Temporary Total Enclosure” under 40 CFR 

52.741, appendix B. The enclosure may have permanent or temporary openings to allow worker 

access; passage of material into or out of the enclosure by conveyor, vehicles, or other 

mechanical means; entry of permanent mechanical or electrical equipment; or to direct airflow 

into the enclosure. The owner or operator shall perform the verification procedure for the 

enclosure as specified in Section 5.0 to “Procedure T—Criteria for and Verification of a 

Permanent or Temporary Total Enclosure” initially when the enclosure is first installed and, 

thereafter, annually. 

(2) The enclosure shall be vented through a closed-vent system to an enclosed combustion 

control device that is designed and operated in accordance with the standards for either a vapor 

incinerator, boiler, or process heater specified in §63.693 of this subpart. 

(3) The owner or operator shall inspect and monitor the closed-vent system and control device as 

specified in § 63.693.

§63.686 Standards: Oil-water and organic-water 

separators.

(a) The provisions of this section apply to the control of air emissions from oil-water separators 

and organic-water separators for which §63.683(b)(1)(i) of this subpart references the use of this 

section for such air emission control. 

(b) The owner or operator shall control air emissions from each separator subject to this section 

by using one of the following:

(1) A floating roof in accordance with all applicable provisions specified in 40 CFR 63 subpart 

VV—National Emission Standards for Oil-Water Separators and Organic-Water Separators, 

except that §§ 63.1043(c)(2), 63.1044(c)(2) and 63.1045(b)(3)(i) shall not apply for the purposes 

of this subpart. For portions of the separator where it is infeasible to install and operate a floating 

roof, such as over a weir mechanism, the owner or operator shall comply with the requirements 

specified in paragraph (b)(2) of this section. 

(2) A fixed-roof that is vented through a closed-vent system to a control device in accordance 

with all applicable provisions specified in 40 CFR 63 subpart VV—National Emission Standards 

for Oil-Water Separators and Organic-Water Separators, except that §§ 63.1043(c)(2), 

63.1044(c)(2) and 63.1045(b)(3)(i) shall not apply for the purposes of this subpart. 
(3) A pressurized separator that operates as a closed system in accordance with all applicable 

provisions specified in 40 CFR part 63, subpart VV—National Emission Standards for Oil-Water 

Separators and Organic-Water Separators, except that §§ 63.1043(c)(2), 63.1044(c)(2) and 

63.1045(b)(3)(i) shall not apply for the purposes of this subpart.

§63.687 Standards: Surface impoundments.

(a) The provisions of this section apply to the control of air emissions from surface 

impoundments for which §63.683(b)(1)(i) of this subpart references the use of this section for 

such air emission control. 

(b) The owner or operator shall control air emissions from each surface impoundment subject to 

this section by using one of the following:

(1) A floating membrane cover in accordance with the applicable provisions specified in 40 CFR 

63 subpart QQ—National Emission Standards for Surface Impoundments, except that 

§§ 63.942(c)(2) and (3) and 63.943(c)(2) shall not apply for the purposes of this subpart; or 

(2) A cover that is vented through a closed-vent system to a control device in accordance with all 

applicable provisions specified in 40 CFR 63 subpart QQ—National Emission Standards for 

Surface Impoundments, except that §§ 63.942(c)(2) and (3) and 63.943(c)(2) shall not apply for 

the purposes of this subpart. 

§63.688 Standards: Containers.

(a) The provisions of this section apply to the control of air emissions from containers for which 

§63.683(b)(1)(i) of this subpart references the use of this section for such air emission control. 

(b) The owner or operator shall control air emissions from each container subject to this section 

in accordance with the following requirements, as applicable to the container, except when the 

special provisions for waste stabilization processes specified in paragraph (c) of this section 

apply to the container.

(1) For a container having a design capacity greater than 0.1 m3and less than or equal to 0.46 m3, 

the owner or operator must control air emissions from the container in accordance with the 

requirements in either paragraph (b)(1)(i) or (b)(1)(ii) of this section.

(i) The owner or operator controls air emissions from the container in accordance with the 

standards for Container Level 1 controls as specified in 40 CFR part 63, subpart PP—National 

Emission Standards for Containers, except that §§ 63.922(d)(4) and (5) and 63.923(d)(4) and (5) 

shall not apply for the purposes of this subpart.

(ii) As an alternative to meeting the requirements in paragraph (b)(1)(i) of this section, an owner 

or operator may choose to control air emissions from the container in accordance with the 

standards for either Container Level 2 controls or Container Level 3 controls as specified in 
subpart PP of this part 63—National Emission Standards for Containers, except that

§§ 63.922(d)(4) and (5) and 63.923(d)(4) and (5) shall not apply for the purposes of this subpart.

(2) For a container having a design capacity greater than 0.46 m3 and the container is not in lightmaterial service as defined in §63.681 of this subpart, the owner or operator must control air 

emissions from the container in accordance with the requirements in either paragraph (b)(1)(i) or 

(b)(1)(ii) of this section.

(3) For a container having a design capacity greater than 0.46 m3and the container is in lightmaterial service as defined in §63.681 of this subpart, the owner or operator must control air 

emissions from the container in accordance with the requirements in either paragraph (b)(3)(i) or 

(b)(3)(ii) of this section.

(i) The owner or operator controls air emissions from the container in accordance with the 

standards for Container Level 2 controls as specified in 40 CFR part 63, subpart PP—National 

Emission Standards for Containers, except that §§ 63.922(d)(4) and (5) and 63.923(d)(4) and (5) 

shall not apply for the purposes of this subpart.

(ii) As an alternative to meeting the requirements in paragraph (b)(3)(i) of this section, an owner 

or operator may choose to control air emissions from the container in accordance with the 

standards for Container Level 3 controls as specified in 40 CFR part 63, subpart PP—National 

Emission Standards for Containers.

(c) When a container subject to this subpart and having a design capacity greater than 0.1 m3is 

used for treatment of an off-site material by a waste stabilization process as defined in §63.681 

of this subpart, the owner or operator shall control air emissions from the container at those times 

during the process when the off-site material in the container is exposed to the atmosphere in 

accordance with the standards for Container Level 3 controls as specified in 40 CFR part 63, 

subpart PP—National Emission Standards for Containers.

§63.689 Standards: Transfer systems.

(a) The provisions of this section apply to the control of air emissions from transfer systems for 

which §63.683(b)(1)(i) of this subpart references the use of this section for such air emission 

control. 

(b) For each transfer system that is subject to this section and is an individual drain system, the 

owner or operator shall control air emissions in accordance with the standards specified in 40 

CFR part 63, subpart RR—National Emission Standards for Individual Drain Systems.

(c) For each transfer system that is subject to this section but is not an individual drain system, 

the owner or operator shall control air emissions by using one of the transfer systems specified in 

paragraphs (c)(1) through (c)(3) of this section.

(1) A transfer system that uses covers in accordance with the requirements specified in paragraph 

(d) of this section.
(2) A transfer system that consists of continuous hard-piping. All joints or seams between the 

pipe sections shall be permanently or semi-permanently sealed (e.g., a welded joint between two 

sections of metal pipe or a bolted and gasketed flange).

(3) A transfer system that is enclosed and vented through a closed-vent system to a control 

device in accordance with the requirements specified in paragraphs (c)(3)(i) and (c)(3)(ii) of this 

section.

(i) The transfer system is designed and operated such that an internal pressure in the vapor 

headspace in the enclosure is maintained at a level less than atmospheric pressure when the 

control device is operating, and 

(ii) The closed-vent system and control device are designed and operated in accordance with the 

requirements of §63.693 of this subpart.

(d) Owners and operators controlling air emissions from a transfer system using covers in 

accordance with the provisions of paragraph (c)(1) of this section shall meet the requirements 

specified in paragraphs (d)(1) through (d)(6) of this section.

(1) The cover and its closure devices shall be designed to form a continuous barrier over the 

entire surface area of the off-site material as it is conveyed by the transfer system except for the 

openings at the inlet and outlet to the transfer system through which the off-site material passes. 

The inlet and outlet openings used for passage of the off-site material through the transfer system 

shall be the minimum size required for practical operation of the transfer system. 

(2) The cover shall be installed in a manner such that there are no visible cracks, holes, gaps, or 

other open spaces between cover section joints or between the interface of the cover edge and its 

mounting. 

(3) Except for the inlet and outlet openings to the transfer system through which the off-site 

material passes, each opening in the cover shall be equipped with a closure device designed to 

operate such that when the closure device is secured in the closed position there are no visible 

cracks, holes, gaps, or other open spaces in the closure device or between the perimeter of the 

opening and the closure device. 

(4) The cover and its closure devices shall be made of suitable materials that will minimize 

exposure of the off-site material to the atmosphere, to the extent practical, and will maintain the 

integrity of the equipment throughout its intended service life. Factors to be considered when 

selecting the materials for and designing the cover and closure devices shall include: organic 

vapor permeability; the effects of any contact with the material or its vapors conveyed in the 

transfer system; the effects of outdoor exposure to wind, moisture, and sunlight; and the 

operating practices used for the transfer system on which the cover is installed. 

(5) Whenever an off-site material is in the transfer system, the cover shall be installed with each 

closure device secured in the closed position, except the opening of closure devices or removal 

of the cover is allowed to provide access to the transfer system for performing routine inspection, 
maintenance, repair, or other activities needed for normal operations. Examples of such activities 

include those times when a worker needs to open a hatch or remove the cover to repair 

conveyance equipment mounted under the cover or to clear a blockage of material inside the 

system. Following completion of the activity, the owner or operator shall promptly secure the 

closure device in the closed position or reinstall the cover, as applicable. . 

(6) The owner or operator shall inspect the air emission control equipment in accordance with 

the requirements specified in §63.695 of this subpart. 

§63.690 Standards: Process vents.

(a) The provisions of this section apply to the control of air emissions from process vents for 

which §63.683(c)(1)(i) of this subpart references the use of this section for such air emission 

control.

(b) The owner or operator must route the vent stream from each affected process vent through a 

closed-vent system to a control device that meets the standards specified in §63.693 of this 

subpart. For the purpose of complying with this paragraph (b), a primary condenser is not a 

control device; however, a second condenser or other organic recovery device that is operated 

downstream of the primary condenser is considered a control device.

§63.691 Standards: Equipment leaks.

(a) The provisions of this section apply to the control of air emissions from equipment leaks for 

which §63.683(d) references the use of this section for such air emissions control.

(b) According to the date an affected source commenced construction or reconstruction and the 

date an affected source receives off-site material for the first time, as established in 

§ 63.680(e)(i) through (iii) of this subpart, the owner or operator shall control the HAP emitted 

from equipment leaks in accordance with the applicable provisions specified in either paragraph 

(b)(1) or (b)(2) of this section.

(1) (i) The owner or operator controls the HAP emitted from equipment leaks in accordance with 

§§ 61.241 through 61.247 in 40 CFR part 61, subpart V—National Emission Standards for 

Equipment Leaks, with the difference noted in paragraphs (b)(1)(iii) and (iv) of this section for 

the purposes of this subpart; or ii) The owner or operator controls the HAP emitted from 

equipment leaks in accordance with §§ 63.161 through 63.182 in 40 CFR part 63, subpart H—

National Emission Standards for Organic Hazardous Air Pollutants from Equipment Leaks, with 

the differences noted in paragraphs (b)(2)(i) through (iv) of this section for the purposes of this 

subpart.

(iii) On or after [DATE OF PUBLICATION OF THE FINAL RULE AMENDMENTS IN THE 

FEDERAL REGISTER], for the purpose of complying with the requirements of 40 CFR 

61.242-6(a)(2) or the requirements of 40 CFR 63.167(a)(2), the open end is sealed when 
instrument monitoring of the open-ended valve or line conducted according to Method 21 of 40 

CFR part 60, appendix A indicates no readings of 500 ppm or greater.

(iv) On or after [DATE OF PUBLICATION OF THE FINAL RULE AMENDMENTS IN THE 

FEDERAL REGISTER], for the purpose of complying with the requirements of 40 CFR 

61.242-6(d) or the requirements of 40 CFR 63.167(d), open-ended valves or lines in an 

emergency shutdown system which are designed to open automatically in the event of a process 

upset and that are exempt from the requirements in 40 CFR 61.242-6(a), (b), and (c) or 40 CFR 

63.167(a), (b) and (c) must comply with the requirements in § 63.693(c)(2) of this subpart.

(2) The owner or operator controls the HAP emitted from equipment leaks in accordance with §§

63.161 through 63.183 in 40 CFR part 63, subpart H – National Emission Standards for Organic 

Hazardous Air Pollutants for Equipment Leaks, with the differences noted in paragraphs (b)(2)(i)

through (v) of this section for the purposes of this subpart. (i) For each valve in gas/vapor or in 

light liquid service, as defined in § 63.681 of this subpart, that is part of an affected source under 

this subpart, an instrument reading that defines a leak is 500 ppm or greater as detected by 

Method 21 of 40 CFR part 60, appendix A.

(ii) For each pump in light liquid service, as defined in § 63.681 of this subpart, that is part of an 

affected source under this subpart, an instrument reading that defines a leak is 1,000 ppm or 

greater as detected by Method 21 of 40 CFR part 60, appendix A. Repair is not required unless 

an instrument reading of 2,000 ppm or greater is detected.

(iii) On or after [DATE OF PUBLICATION OF THE FINAL RULE IN THE FEDERAL 

REGISTER], for the purpose of complying with the requirements of 40 CFR 63.167(a)(2), the 

open end is sealed when instrument monitoring of the open-ended valve or line conducted 

according to Method 21 of 40 CFR part 60, appendix A indicates no readings of 500 ppm or 

greater.

(iv) On or after [DATE OF PUBLICATION OF THE FINAL RULE IN THE FEDERAL 

REGISTER], for the purpose of complying with the requirements of 40 CFR 63.167(d), openended valves or lines in an emergency shutdown system which are designed to open 

automatically in the event of a process upset and that are exempt from the requirements in 40 

CFR 63.167(a), (b) and (c) must comply with the requirements in § 63.693(c)(2) of this subpart.

(v) For the purposes of this subpart, the pressure relief device requirements of § 63.691(c) of this 

subpart rather than those of 40 CFR 63.165 or of 40 CFR 61.242-4, as applicable, shall apply. 

The pressure relief device requirements of § 63.691(c)(3) and (4) of this subpart apply in 

addition to the requirements of 40 CFR 63.169 or of 40 CFR 61.242-8, as applicable , for 

pressure relief devices in liquid service.

(c) Requirements for pressure relief devices. Except as provided in paragraph (c)(4) of this 

section, the owner or operator must comply with the requirements specified in paragraphs (c)(1) 

through (3) of this section for pressure relief devices in off-site material service.
(1) Operating requirements. Except during a pressure release event, operate each pressure relief 

device in gas/vapor service with an instrument reading of less than 500 ppm above background 

as detected by Method 21 of 40 CFR part 60, appendix A.

(2) Pressure release requirements. For pressure relief devices in gas/vapor service, the owner or 

operator must comply with either paragraph (c)(2)(i) or (ii) of this section following a pressure 

release, as applicable.

(i) If the pressure relief device does not consist of or include a rupture disk, the pressure relief 

device shall be returned to a condition indicated by an instrument reading of less than 500 ppm 

above background, as detected by Method 21 of 40 CFR part 60, appendix A, no later than 5 

calendar days after the pressure release device returns to off-site material service following a 

pressure release, except as provided in 40 CFR 63.171. 

(ii) If the pressure relief device consists of or includes a rupture disk, except as provided in 40 

CFR 63.171, install a replacement disk as soon as practicable but no later than 5 calendar days 

after the pressure release.

(3) Pressure release management. Except as provided in paragraph (c)(4) of this section, 

emissions of HAP listed in Table 1 of this subpart may not be discharged directly to the 

atmosphere from pressure relief devices in off-site material service, and according to the date an 

affected source commenced construction or reconstruction and the date an affected source

receives off-site material for the first time, as established in § 63.680(e)(i) through (iii) of this 

subpart, the owner or operator must comply with the requirements specified in paragraphs 

(c)(3)(i) and (ii) of this section for all pressure relief devices in off-site material service.

(i) The owner or operator must equip each pressure relief device in off-site material service with 

a device(s) or use a monitoring system. The device or monitoring system may be either specific 

to the pressure release device itself or may be associated with the process system or piping, 

sufficient to indicate a pressure release to the atmosphere. Examples of these types of devices 

include, but are not limited to a rupture disk indicator, magnetic sensor, motion detector on the 

pressure relief valve stem, flow monitor, pressure monitor, or parametric monitoring system. The 

devices or monitoring systems must be capable of meeting the requirements specified in 

paragraphs (c)(3)(i)(A) through (C) of this section.

(A) Identifying the pressure release; 

(B) Recording the time and duration of each pressure release; and 

(C) Notifying operators immediately that a pressure release is occurring. 

(ii) If any pressure relief device in off-site material service releases directly to the atmosphere as 

a result of a pressure release event, the owner or operator must calculate the quantity of HAP

listed in Table 1 of this subpart released during each pressure release event and report this 

quantity as required in § 63.697(b)(5) of this subpart. Calculations may be based on data from 
the pressure relief device monitoring alone or in combination with process parameter monitoring 

data and process knowledge. 

(4) Pressure relief devices routed to a drain system, fuel gas system, process or control device. If 

a pressure relief device in off-site material service is designed and operated to route all pressure 

releases through a closed vent system to a control device or to a drain system, fuel gas system, 

process or control device, paragraphs (c)(1), (2), and (3) of this section do not apply. The fuel 

gas system or closed vent system and the process or control device (if applicable) must meet the 

requirements of § 63.693 of this subpart. The drain system (if applicable) must meet the 

requirements of § 63.689 of this subpart.

§63.692 [Reserved]

§63.693 Standards: Closed-vent systems and control 

devices.

(a) The provisions of this section apply to closed-vent systems and control devices used to 

control air emissions for which another standard references the use of this section for such air 

emission control.

(b) For each closed-vent system and control device used to comply with this section, the owner 

or operator shall meet the following requirements:

(1) The owner or operator must use a closed-vent system that meets the requirements specified in 

paragraph (c) of this section.

(2) The owner or operator must use a control device that meets the requirements specified in 

paragraphs (d) through (h) of this section as applicable to the type and design of the control 

device selected by the owner or operator to comply with the provisions of this section.

(3) Whenever gases or vapors containing HAP are routed from a tank through a closed-vent 

system connected to a control device used to comply with the requirements of 

§ 63.685(b)(1), (2) or (3) of this subpart, the control device must be operating except as provided 

for in paragraphs (b)(3)(i) and (b)(3)(ii) of this section.

(i) The control device may only be bypassed for the purpose of performing planned routine 

maintenance of the closed-vent system or control device in situations when the routine 

maintenance cannot be performed during periods that tank emissions are vented to the control 

device.

(ii) On an annual basis, the total time that the closed-vent system or control device is bypassed to 

perform routine maintenance shall not exceed 240 hours per each calendar year.

(4) The owner or operator must inspect and monitor each closed-vent system in accordance with 

the requirements specified in either paragraph (b)(4)(i) or (b)(4)(ii) of this section.
(i) The owner or operator inspects and monitors the closed-vent system in accordance with the 

requirements specified in §63.695(c) of this subpart, and complies with the applicable 

recordkeeping requirements in §63.696 of this subpart and the applicable reporting requirements 

in §63.697 of this subpart.

(ii) As an alternative to meeting the requirements specified in paragraph (b)(4)(i) of this section, 

the owner or operator may choose to inspect and monitor the closed-vent system in accordance 

with the requirements under 40 CFR part 63, subpart H—National Emission Standards for 

Organic Hazardous Air Pollutants for Equipment Leaks as specified in 40 CFR 63.172(f) through 

(h), and complies with the applicable recordkeeping requirements in 40 CFR 63.181 and the 

applicable reporting requirements in 40 CFR 63.182.

(5) The owner or operator must monitor the operation of each control device in accordance with 

the requirements specified in paragraphs (d) through (h) of this section as applicable to the type 

and design of the control device selected by the owner or operator to comply with the provisions 

of this section.

(6) The owner or operator shall maintain records for each control device in accordance with the 

requirements of §63.696 of this subpart.

(7) The owner or operator shall prepare and submit reports for each control device in accordance 

with the requirements of §63.697 of this subpart.

(8) In the case when an owner or operator chooses to use a design analysis to demonstrate 

compliance of a control device with the applicable performance requirements specified in this 

section as provided for in paragraphs (d) through (g) of this section, the Administrator may

require that the design analysis be revised or amended by the owner or operator to correct any

deficiencies identified by the Administrator. If the owner or operator and the Administrator do 

not agree on the acceptability of using the design analysis (including any changes required by the 

Administrator) to demonstrate that the control device achieves the applicable performance 

requirements, then the disagreement must be resolved using the results of a performance test 

conducted by the owner or operator in accordance with the requirements of §63.694(l) of this 

subpart. The Administrator may choose to have an authorized representative observe the 

performance test conducted by the owner or operator. Should the results of this performance test 

not agree with the determination of control device performance based on the design analysis, 

then the results of the performance test will be used to establish compliance with this subpart.

(c) Closed-vent system requirements.

(1) The vent stream required to be controlled shall be conveyed to the control device by either of 

the following closed-vent systems:

(i) A closed-vent system that is designed to operate with no detectable organic emissions using 

the procedure specified in §63.694(k) of this subpart; or 
(ii) A closed-vent system that is designed to operate at a pressure below atmospheric pressure. 

The system shall be equipped with at least one pressure gauge or other pressure measurement 

device that can be read from a readily accessible location to verify that negative pressure is being 

maintained in the closed-vent system when the control device is operating.

(2) In situations when the closed-vent system includes bypass devices that could be used to 

divert a vent stream from the closed-vent system to the atmosphere at a point upstream of the 

control device inlet, each bypass device must be equipped with either a flow indicator as 

specified in paragraph (c)(2)(i) of this section or a seal or locking device as specified in 

paragraph (c)(2)(ii) of this section, except as provided for in paragraph (c)(2)(iii) of this 

section:(i) If a flow indicator is used, the indicator must be installed at the entrance to the bypass 

line used to divert the vent stream from the closed-vent system to the atmosphere. The flow 

indicator must indicate a reading at least once every 15 minutes. The owner or operator must 

maintain records of the following information: hourly records of whether the flow indicator was 

operating and whether flow was detected at any time during the hour; and records of all periods 

when flow is detected or the flow indicator is not operating.

(ii) If a seal or locking device is used to comply with paragraph (c)(2) of this section, the device 

shall be placed on the mechanism by which the bypass device position is controlled (e.g., valve 

handle, damper lever) when the bypass device is in the closed position such that the bypass 

device cannot be opened without breaking the seal or removing the lock. Examples of such 

devices include, but are not limited to, a car-seal or a lock-and-key configuration valve.

(iii) Equipment needed for safety reasons, including low leg drains, open-ended valves and lines 

not in emergency shutdown systems, and pressure relief devices subject to the requirements of 

§ 63.691(c) of this subpart are not subject to the requirements of paragraphs (c)(2)(i) and (ii) of 

this section.

(d) Carbon adsorption control device requirements.

(1) The carbon adsorption system must achieve the performance specifications in either 

paragraph (d)(1)(i) or (d)(1)(ii) of this section.

(i) Recover 95 percent or more, on a weight-basis, of the total organic compounds (TOC), less 

methane and ethane, contained in the vent stream entering the carbon adsorption system; or

(ii) Recover 95 percent or more, on a weight-basis, of the total HAP listed in Table 1 of this 

subpart contained in the vent stream entering the carbon adsorption system.

(2) The owner or operator must demonstrate that the carbon adsorption system achieves the 

performance requirements in paragraph (d)(1) of this section by either performing a performance 

test as specified in paragraph (d)(2)(i) of this section or a design analysis as specified in 

paragraph (d)(2)(ii) of this section.

(i) An owner or operator choosing to use a performance test to demonstrate compliance must 

conduct the test in accordance with the requirements of §63.694(l) of this subpart.
(ii) An owner or operator choosing to use a design analysis to demonstrate compliance must 

include as part of this design analysis the information specified in either paragraph (d)(2)(ii)(A) 

or (d)(2)(ii)(B) of this section as applicable to the carbon adsorption system design.

(A) For a regenerable carbon adsorption system, the design analysis shall address the vent stream 

composition, constituent concentrations, flow rate, relative humidity, and temperature and shall 

establish the design exhaust vent stream organic compound concentration, adsorption cycle time, 

number and capacity of carbon beds, type and working capacity of activated carbon used for 

carbon beds, design total regeneration steam flow over the period of each complete carbon bed 

regeneration cycle, design carbon bed temperature after regeneration, design carbon bed 

regeneration time, and design service life of the carbon.

(B) For a nonregenerable carbon adsorption system (e.g., a carbon canister), the design analysis 

shall address the vent stream composition, constituent concentrations, flow rate, relative 

humidity, and temperature and shall establish the design exhaust vent stream organic compound 

concentration, carbon bed capacity, activated carbon type and working capacity, and design 

carbon replacement interval based on the total carbon working capacity of the control device and 

emission point operating schedule.

(3) The owner or operator must monitor the operation of the carbon adsorption system in 

accordance with the requirements of §63.695(e) using one of the continuous monitoring systems 

specified in paragraphs (d)(3)(i) through (iii) of this section. Monitoring the operation of a 

nonregenerable carbon adsorption system (e.g., a carbon canister) using a continuous monitoring 

system is not required when the carbon canister or the carbon in the control device is replaced on 

a regular basis according to the requirements in paragraph (d)(4)(iii) of this section.

(i) For a regenerative-type carbon adsorption system:

(A) A continuous parameter monitoring system to measure and record the average total 

regeneration stream mass flow or volumetric flow during each carbon bed regeneration cycle. 

The integrating regenerating stream flow monitoring device must have an accuracy of ±10 

percent; and

(B) A continuous parameter monitoring system to measure and record the average carbon bed 

temperature for the duration of the carbon bed steaming cycle and to measure the actual carbon 

bed temperature after regeneration and within 15 minutes of completing the cooling cycle. The 

accuracy of the temperature monitoring device must be ±1 percent of the temperature being 

measured, expressed in degrees Celsius or ±5 °C, whichever is greater.

(ii) A continuous monitoring system to measure and record the daily average concentration level 

of organic compounds in the exhaust gas stream from the control device. The organic monitoring 

system must comply either with Performance Specification 8 or 9 in 40 CFR part 60, appendix 

B. The relative accuracy provision of Performance Specification 8, Sections 2.4 and 3 need not 

be conducted.
(iii) A continuous monitoring system that measures other alternative operating parameters upon 

approval of the Administrator as specified in 40 CFR 63.8(f)(1) through (f)(5) of this part.

(4) The owner or operator shall manage the carbon used for the carbon adsorption system, as 

follows:

(i) Following the initial startup of the control device, all carbon in the control device shall be 

replaced with fresh carbon on a regular, predetermined time interval that is no longer than the 

carbon service life established for the carbon adsorption system. The provisions of this paragraph 

(d)(4)(i) do not apply to a nonregenerable carbon adsorption system (e.g., a carbon canister) for 

which the carbon canister or the carbon in the control device is replaced on a regular basis 

according to the requirements in paragraph (d)(4)(iii) of this section.

(ii) The spent carbon removed from the carbon adsorption system must be either regenerated, 

reactivated, or burned in one of the units specified in paragraphs (d)(4)(ii)(A) through 

(d)(4)(ii)(G) of this section.

(A) Regenerated or reactivated in a thermal treatment unit for which the owner or operator has 

been issued a final permit under 40 CFR part 270 that implements the requirements of 40 CFR 

part 264, subpart X.

(B) Regenerated or reactivated in a thermal treatment unit equipped with and operating air 

emission controls in accordance with this section.

(C) Regenerated or reactivated in a thermal treatment unit equipped with and operating organic 

air emission controls in accordance with a national emission standard for hazardous air pollutants 

under another subpart in 40 CFR part 63 or 40 CFR part 61.

(D) Burned in a hazardous waste incinerator for which the owner or operator has been issued a 

final permit under 40 CFR part 270 that implements the requirements of 40 CFR part 264, 

subpart O.

(E) Burned in a hazardous waste incinerator for which the owner or operator has designed and 

operates the incinerator in accordance with the interim status requirements of 40 CFR part 265, 

subpart O.

(F) Burned in a boiler or industrial furnace for which the owner or operator has been issued a 

final permit under 40 CFR part 270 that implements the requirements of 40 CFR part 266, 

subpart H.

(G) Burned in a boiler or industrial furnace for which the owner or operator has designed and 

operates the unit in accordance with the interim status requirements of 40 CFR part 266, subpart 

H.

(iii) As an alternative to meeting the requirements in paragraphs (d)(3) and (d)(4)(i) of this 

section, an owner or operator of a nonregenerable carbon adsorption system may choose to 
replace on a regular basis the carbon canister or the carbon in the control device using the 

procedures in either paragraph (d)(4)(iii)(A) or (d)(4)(iii)(B) of this section. For the purpose of 

complying with this paragraph (d)(4)(iii), a nonregenerable carbon adsorption system means a 

carbon adsorption system that does not regenerate the carbon bed directly onsite in the control 

device, such as a carbon canister. The spent carbon removed from the nonregenerable carbon 

adsorption system must be managed according to the requirements in paragraph (d)(4)(ii) of this 

section.

(A) Monitor the concentration level of the organic compounds in the exhaust vent from the 

carbon adsorption system on a regular schedule, and when carbon breakthrough is indicated, 

immediately replace either the existing carbon canister with a new carbon canister or replace the 

existing carbon in the control device with fresh carbon. Measurement of the concentration level 

of the organic compounds in the exhaust vent stream must be made with a detection instrument 

that is appropriate for the composition of organic constituents in the vent stream and is routinely 

calibrated to measure the organic concentration level expected to occur at breakthrough. The 

monitoring frequency must be daily or at an interval no greater than 20 percent of the time 

required to consume the total carbon working capacity established as a requirement of paragraph 

(d)(2)(ii)(B) of this section, whichever is longer.

(B) Replace either the existing carbon canister with a new carbon canister or replace the existing 

carbon in the control device with fresh carbon at a regular, predetermined time interval that is 

less than the design carbon replacement interval established as a requirement of paragraph 

(d)(2)(ii)(B) of this section.

(e) Condenser control device requirements.

(1) The condenser must achieve the performance specifications in either paragraph (e)(1)(i) or 

(e)(1)(ii) of this section.

(i) Recover 95 percent or more, on a weight-basis, of the total organic compounds (TOC), less 

methane and ethane, contained in the vent stream entering the condenser; or

(ii) Recover 95 percent or more, on a weight-basis, of the total HAP, listed in Table 1 of this 

subpart, contained in the vent stream entering the condenser.

(2) The owner or operator must demonstrate that the condenser achieves the performance 

requirements in paragraph (e)(1) of this section by either performing a performance test as 

specified in paragraph (e)(2)(i) of this section or a design analysis as specified in paragraph 

(e)(2)(ii) of this section.

(i) An owner or operator choosing to use a performance tests to demonstrate compliance must 

conduct the test in accordance with the requirements of §63.694(l) of this subpart.

(ii) An owner or operator choosing to use a design analysis to demonstrate compliance must 

include as part of this design analysis the following information: description of the vent stream 

composition, constituent concentrations, flow rate, relative humidity, and temperature; and 
specification of the design outlet organic compound concentration level, design average 

temperature of the condenser exhaust vent stream, and the design average temperatures of the 

coolant fluid at the condenser inlet and outlet.

(3) The owner or operator must monitor the operation of the condenser in accordance with the 

requirements of §63.695(e) of this subpart using one of the continuous monitoring systems 

specified in paragraphs (e)(3)(i) through (e)(3)(iii) of this section.

(i) A continuous parameter monitoring system to measure and record the daily average 

temperature of the exhaust gases from the control device. The accuracy of the temperature 

monitoring device shall be ±1 percent of the temperature being measured, expressed in degrees 

Celsius or ±5 °C, whichever is greater. 

(ii) A continuous monitoring system to measure and record the daily average concentration level 

of organic compounds in the exhaust gas stream from the control device. The organic monitoring 

system must comply either with Performance Specification 8 or 9 in 40 CFR part 60, appendix 

B. The relative accuracy provision of Performance Specification 8, Sections 2.4 and 3 need not 

be conducted.

(iii) A continuous monitoring system that measures other alternative operating parameters upon 

approval of the Administrator as specified in 40 CFR 63.8(f)(1) through (f)(5) of this part.

(f) Vapor incinerator control device requirements.

(1) The vapor incinerator must achieve the performance specifications in either paragraph 

(f)(1)(i), (f)(1)(ii), or (f)(1)(iii) of this section.

(i) Destroy the total organic compounds (TOC), less methane and ethane, contained in the vent 

stream entering the vapor incinerator either:

(A) By 95 percent or more, on a weight-basis, or

(B) To achieve a total incinerator outlet concentration for the TOC, less methane and ethane, of 

less than or equal to 20 ppmv on a dry basis corrected to 3 percent oxygen.

(ii) Destroy the HAP listed in Table 1 of this subpart contained in the vent stream entering the 

vapor incinerator either:

(A) By 95 percent or more, on a total HAP weight-basis, or

(B) To achieve a total incinerator outlet concentration for the HAP, listed in Table 1 of this 

subpart, of less than or equal to 20 ppmv on a dry basis corrected to 3 percent oxygen.

(iii) Maintain the conditions in the vapor incinerator combustion chamber at a residence time of 

0.5 seconds or longer and at a temperature of 760°C or higher.
(2) The owner or operator must demonstrate that the vapor incinerator achieves the performance 

requirements in paragraph (f)(1) of this section by conducting either a performance test as 

specified in paragraph (f)(2)(i) of this section or a design analysis as specified in paragraph 

(f)(2)(ii) of this section, except as provided for in paragraph (f)(2)(iii) of this section.

(i) An owner or operator choosing to use a performance test to demonstrate compliance must 

conduct the test in accordance with the requirements of §63.694(l) of this subpart.

(ii) An owner or operator choosing to use a design analysis to demonstrate compliance must 

include as part of this design analysis the information specified in either paragraph (f)(2)(ii)(A) 

or (f)(2)(ii)(B) of this section as applicable to the vapor incinerator design.

(A) For a thermal vapor incinerator, the design analysis shall address the vent stream 

composition, constituent concentrations, and flow rate and shall establish the design minimum 

and average temperatures in the combustion chamber and the combustion chamber residence 

time.

(B) For a catalytic vapor incinerator, the design analysis shall address the vent stream 

composition, constituent concentrations, and flow rate and shall establish the design minimum 

and average temperatures across the catalyst bed inlet and outlet, and the design service life of 

the catalyst.

(iii) An owner or operator is not required to conduct a performance test or design analysis if the 

incinerator has been issued a final permit under 40 CFR part 270 and complies with the 

requirements of 40 CFR part 264, subpart O, or has certified compliance with the interim status 

requirements of 40 CFR part 265, subpart O. 

(3) The owner or operator must monitor the operation of the vapor incinerator in accordance with 

the requirements of §63.695(e) of this subpart using one of the continuous monitoring systems 

specified in paragraphs (f)(3)(i) through (f)(3)(iv) of this section as applicable to the type of 

vapor incinerator used.

(i) For a thermal vapor incinerator, a continuous parameter monitoring system to measure and 

record the daily average temperature of the exhaust gases from the control device. The accuracy 

of the temperature monitoring device must be ±1 percent of the temperature being measured, 

expressed in degrees Celsius of ±0.5 °C, whichever is greater.

(ii) For a catalytic vapor incinerator, a temperature monitoring device capable of monitoring 

temperature at two locations equipped with a continuous recorder. One temperature sensor shall 

be installed in the vent stream at the nearest feasible point to the catalyst bed inlet and a second 

temperature sensor shall be installed in the vent stream at the nearest feasible point to the catalyst 

bed outlet.

(iii) For either type of vapor incinerator, a continuous monitoring system to measure and record 

the daily average concentration of organic compounds in the exhaust vent stream from the 

control device. The organic monitoring system must comply either with Performance 
Specification 8 or 9 in 40 CFR part 60, appendix B. The relative accuracy provision of 

Performance Specification 8, Sections 2.4 and 3 need not be conducted.

(iv) For either type of vapor incinerator, a continuous monitoring system that measures 

alternative operating parameters other than those specified in paragraph (f)(3)(i) or (f)(3)(ii) of 

this section upon approval of the Administrator as specified in 40 CFR 63.8(f)(1) through (f)(5) 

of this part.

(g) Boilers and process heaters control device requirements.

(1) The boiler or process heater must achieve the performance specifications in either paragraph 

(g)(1)(i), (g)(1)(ii), (g)(1)(iii), (g)(1)(iv), or (g)(1)(v) of this section.

(i) Destroy the total organic compounds (TOC), less methane and ethane, contained in the vent 

stream introduced into the flame zone of the boiler or process heater either:

(A) By 95 percent or more, on a weight-basis, or 

(B) To achieve in the exhausted combustion gases a total concentration for the TOC, less 

methane and ethane, of less than or equal to 20 parts ppmv on a dry basis corrected to 3 percent 

oxygen.

(ii) Destroy the HAP listed in Table 1 of this subpart contained in the vent stream entering the 

vapor incinerator either:

(A) By 95 percent or more, on a total HAP weight-basis, or 

(B) To achieve in the exhausted combustion gases a total concentration for the HAP, listed in 

Table 1 of the subpart, of less than or equal to 20 ppmv on a dry basis corrected to 3 percent 

oxygen.

(iii) Introduce the vent stream into the flame zone of the boiler or process heater and maintain the 

conditions in the combustion chamber at a residence time of 0.5 seconds or longer and at a 

temperature of 760°C or higher.

(iv) Introduce the vent stream with the fuel that provides the predominate heat input to the boiler 

or process heater (i.e., the primary fuel); or

(v) Introduce the vent stream to a boiler or process heater for which the owner or operator either 

has been issued a final permit under 40 CFR part 270 and complies with the requirements of 40 

CFR part 266, subpart H; or has certified compliance with the interim status requirements of 40 

CFR part 266, subpart H; or has submitted a Notification of Compliance under 40 CFR 

63.1207(j) and 63.1210(d) and complies with the requirements of 40 CFR part 63 subpart EEE at 

all times (including times when non-hazardous waste is being burned).
(2) The owner or operator must demonstrate that the boiler or process heater achieves the 

performance specifications in paragraph (g)(1) of this section chosen by the owner or operator 

using the applicable method specified in paragraph (g)(2)(i) or (g)(2)(ii) of this section.

(i) If an owner or operator chooses to comply with the performance specifications in either 

paragraph (g)(1)(i), (g)(1)(ii), or (g)(1)(iii) of this section, the owner or operator must 

demonstrate compliance with the applicable performance specifications by conducting either a 

performance test as specified in paragraph (g)(2)(i)(A) of this section or a design analysis as 

specified in paragraph (g)(2)(i)(B) of this section, except as provided for in paragraph 

(g)(2)(i)(C) of this section.

(A) An owner or operator choosing to use a performance test to demonstrate compliance must 

conduct the test in accordance with the requirements of §63.694(l) of this subpart.

(B) An owner or operator choosing to use a design analysis to demonstrate compliance must 

include as part of this design analysis the following information: description of the vent stream 

composition, constituent concentrations, and flow rate; specification of the design minimum and 

average flame zone temperatures and combustion zone residence time; and description of the 

method and location by which the vent stream is introduced into the flame zone.

(C) An owner or operator is not required to conduct a performance test or design analysis if the 

boiler or process heater has been issued a final permit under 40 CFR part 270 and complies with 

the requirements of 40 CFR part 266, subpart H; or has certified compliance with the interim 

status requirements of 40 CFR part 266, subpart H.

(ii) If an owner or operator chooses to comply with the performance specifications in either 

paragraph (g)(1)(iv) or (g)(1)(v) of this section, the owner or operator must demonstrate 

compliance by maintaining the records that document that the boiler or process heater is 

designed and operated in accordance with the applicable requirements of this section.

(3) For a boiler or process heater complying with the performance specifications in either 

paragraph (g)(1)(i), (g)(1)(ii), or (g)(1)(iii) of this section, the owner or operator must monitor 

the operation of a boiler or process heater in accordance with the requirements of §63.695(e) of 

this subpart using one of the continuous monitoring systems specified in paragraphs (g)(3)(i) 

through (g)(3)(iii) of this section.

(i) A continuous parameter monitoring system to measure and record the daily average 

combustion zone temperature. The accuracy of the temperature sensor must be ±1 percent of the 

temperature being measured, expressed in degrees Celsius or ±0.5 °C, whichever is greater;

(ii) A continuous monitoring system to measure and record the daily average concentration of 

organic compounds in the exhaust vent stream from the control device. The organic monitoring 

system must comply either with Performance Specification 8 or 9 in 40 CFR part 60, appendix 

B. The relative accuracy provision of Performance Specification 8, Sections 2.4 and 3 need not 

be conducted.
(iii) A continuous monitoring system that measures alternative operating parameters other than 

those specified in paragraph (g)(3)(i) or (g)(3)(ii) of this section upon approval of the 

Administrator as specified in 40 CFR 63.8(f)(1) through (f)(5) of this part.

(h) Flare control device requirements.

(1) The flare must be designed and operated in accordance with the requirements in 40 CFR 

63.11(b).

(2) The owner or operator must demonstrate that the flare achieves the requirements in paragraph 

(h)(1) of this section by performing the procedures specified in paragraph (h)(2)(i) of this 

section. A previous compliance demonstration for the flare that meets all of the conditions 

specified in paragraph (h)(2)(ii) of this section may be used by an owner or operator to 

demonstrate compliance with this paragraph (h)(2).

(i) To demonstrate that a flare achieves the requirements in paragraph (h)(1) of this section, the 

owner or operator performs all of the procedures specified in paragraphs (h)(2)(i)(A) through 

(h)(2)(i)(C) of this section.

(A) The owner or operator conducts a visible emission test for the flare in accordance with the 

requirements specified in 40 CFR 63.11(b)(4).

(B) The owner or operator determines the net heating value of the gas being combusted in the 

flare in accordance with the requirements specified in 40 CFR 63.11(b)(6); and 

(C) The owner or operator determines the flare exit velocity in accordance with the requirements 

applicable to the flare design as specified in 40 CFR 63.11(b)(7) or 40 CFR 63.11(b)(8).

(ii) A previous compliance demonstration for the flare may be used by an owner or operator to 

demonstrate compliance with paragraph (h)(2) of this section provided that all conditions for the 

compliance determination and subsequent flare operation are met as specified in paragraphs 

(h)(2)(ii)(A) and (h)(2)(ii)(B) of this section.

(A) The owner or operator conducted the compliance determination using the procedures 

specified in paragraph (h)(2)(i) of this section.

(B) No flare operating parameter or process changes have occurred since completion of the 

compliance determination which could affect the compliance determination results.

(3) The owner or operator must monitor the operation of the flare using a heat sensing 

monitoring device (including but not limited to a thermocouple, ultraviolet beam sensor, or 

infrared sensor) that continuously detects the presence of a pilot flame. The owner or operator 

must record, for each 1-hour period, whether the monitor was continuously operating and 

whether a pilot flame was continuously present during each hour as required in §63.696(b)(3) of 

this subpart.
§63.694 Testing methods and procedures.

(a) This section specifies the testing methods and procedures required for this subpart to perform 

the following: 

(1) To determine the average VOHAP concentration for off-site material streams at the point-ofdelivery for compliance with standards specified §63.683 of this subpart, the testing methods and 

procedures are specified in paragraph (b) of this section. 

(2) To determine the average VOHAP concentration for treated off-site material streams at the 

point-of-treatment for compliance with standards specified §63.684 of this subpart, the testing 

methods and procedures are specified in paragraph (c) of this section. 

(3) To determine the treatment process VOHAP concentration limit (CR) for compliance with 

standards specified §63.684 of this subpart, the testing methods and procedures are specified in 

paragraph (d) of this section. 

(4) To determine treatment process required HAP removal rate (RMR) for compliance with 

standards specified §63.684 of this subpart, the testing methods and procedures are specified in 

paragraph (e) of this section. 

(5) To determine treatment process actual HAP removal rate (MR) for compliance with 

standards specified §63.684 of this subpart, the testing methods and procedures are specified in 

paragraph (f) of this section. 

(6) To determine treatment process required HAP reduction efficiency (R) for compliance with 

standards specified in §63.684 of this subpart, the testing methods and procedures are specified 

in paragraph (g) of this section. 

(7) To determine treatment process required HAP biodegradation efficiency (Rbio) for compliance 

with standards specified in §63.684 of this subpart, the testing methods and procedures are 

specified in paragraph (h) of this section. 

(8) To determine treatment process required actual HAP mass removal rate (MRbio) for 

compliance with standards specified in§63.684 of this subpart, the testing methods and 

procedures are specified in paragraph (i) of this section. 

(9) To determine maximum organic HAP vapor pressure of off-site materials in tanks for 

compliance with the standards specified in §63.685 of this subpart, the testing methods and 

procedures are specified in paragraph (j) of this section. 

(10) To determine no detectable organic emissions, the testing methods and procedures are 

specified in paragraph (k) of this section. 
(11) To determine closed-vent system and control device performance for compliance with the 

standards specified in §63.693 of this subpart, the testing methods and procedures are specified 

in paragraph (l) of this section. 

(12) To determine process vent stream flow rate and total organic HAP concentration for 

compliance with the standards specified in §63.693 of this subpart, the testing methods and 

procedures are specified in paragraph (m) of this section.

(b) Testing methods and procedures to determine average VOHAP concentration of an off-site 

material stream at the point-of-delivery. 

(1) The average VOHAP concentration of an off-site material at the point-of-delivery shall be 

determined using either direct measurement as specified in paragraph (b)(2) of this section or by

knowledge as specified in paragraph (b)(3) of this section. 

(2) Direct measurement to determine VOHAP concentration—(i) Sampling. Samples of the offsite material stream shall be collected from the container, pipeline, or other device used to 

deliver the off-site material stream to the plant site in a manner such that volatilization of 

organics contained in the sample is minimized and an adequately representative sample is 

collected and maintained for analysis by the selected method. 

(A) The averaging period to be used for determining the average VOHAP concentration for the 

off-site material stream on a mass-weighted average basis shall be designated and recorded. The 

averaging period can represent any time interval that the owner or operator determines is 

appropriate for the off-site material stream but shall not exceed 1 year. 

(B) A sufficient number of samples, but no less than four samples, shall be collected to represent 

the complete range of HAP compositions and HAP quantities that occur in the off-site material 

stream during the entire averaging period due to normal variations in the operating conditions for 

the source or process generating the off-site material stream. Examples of such normal variations 

are seasonal variations in off-site material quantity or fluctuations in ambient temperature. 

(C) All samples shall be collected and handled in accordance with written procedures prepared 

by the owner or operator and documented in a site sampling plan. This plan shall describe the 

procedure by which representative samples of the off-site material stream are collected such that 

a minimum loss of organics occurs throughout the sample collection and handling process and by 

which sample integrity is maintained. A copy of the written sampling plan shall be maintained 

on-site in the plant site operating records. An example of an acceptable sampling plan includes a 

plan incorporating sample collection and handling procedures in accordance with the 

requirements specified in “Test Methods for Evaluating Solid Waste, Physical/Chemical 

Methods,” EPA Publication No. SW-846 or Method 25D in 40 CFR part 60, appendix A. 

(ii) Analysis. Each collected sample must be prepared and analyzed in accordance with one of the 

following methods as applicable to the sampled off-site material for the purpose of measuring the 

HAP listed in Table 1 of this subpart:
(A) Method 305 in 40 CFR part 63, appendix A.

(B) Method 25D in 40 CFR part 60, appendix A.

(C) Method 624 in 40 CFR part 136, appendix A. If this method is used to analyze one or more 

compounds that are not on the method's published list of approved compounds, the Alternative 

Test Procedure specified in 40 CFR 136.4 and 40 CFR 136.5 must be followed.

(D) Method 625 in 40 CFR part 136, appendix A. For the purpose of using this method to 

comply with this subpart, the owner or operator must perform corrections to these compounds 

based on the “accuracy as recovery” using the factors in Table 7 of the method. If this method is 

used to analyze one or more compounds that are not on the method's published list of approved 

compounds, the Alternative Test Procedure specified in 40 CFR 136.4 and 40 CFR 136.5 must 

be followed.

(E) Method 1624 in 40 CFR part 136, appendix A.

(F) Method 1625 in 40 CFR part 136, appendix A.

(G) Method 8260 in “Test Methods for Evaluating Solid Waste, Physical/Chemical Methods,” 

EPA Publication No. SW-846, Third Edition, September 1986, as amended by Update I, 

November 15, 1992. As an alternative, an owner or operator may use any more recent, updated 

version of Method 8260 approved by the EPA. For the purpose of using Method 8260 to comply

with this subpart, the owner or operator must maintain a formal quality assurance program 

consistent with section 8 of Method 8260, and this program must include the following elements 

related to measuring the concentrations of volatile compounds:

(1) Documentation of site-specific procedures to minimize the loss of compounds due to 

volatilization, biodegradation, reaction, or sorption during the sample collection, storage, and 

preparation steps.

(2) Documentation of specific quality assurance procedures followed during sampling, sample 

preparation, sample introduction, and analysis.

(3) Measurement of the average accuracy and precision of the specific procedures, including 

field duplicates and field spiking of the off-site material source before or during sampling with 

compounds having similar chemical characteristics to the target analytes.

(H) Method 8270 in “Test Methods for Evaluating Solid Waste, Physical/Chemical Methods,” 

EPA Publication No. SW-846, Third Edition, September 1986, as amended by Update I, 

November 15, 1992. As an alternative, an owner or operator may use any more recent, updated 

version of Method 8270 approved by the EPA. For the purpose of using Method 8270 to comply

with this subpart, the owner or operator must maintain a formal quality assurance program 

consistent with Method 8270, and this program must include the following elements related to 

measuring the concentrations of volatile compounds:
(1) Documentation of site-specific procedures to minimize the loss of compounds due to 

volatilization, biodegradation, reaction, or sorption during the sample collection, storage, and 

preparation steps.

(2) Documentation of specific quality assurance procedures followed during sampling, sample 

preparation, sample introduction, and analysis.

(3) Measurement of the average accuracy and precision of the specific procedures, including 

field duplicates and field spiking of the off-site material source before or during sampling with 

compounds having similar chemical characteristics to the target analytes.

(I) Any other analysis method that has been validated in accordance with the procedures 

specified in section 5.1 and section 5.3 and the corresponding calculations in section 6.1 or 

section 6.3 of Method 301 in appendix A in 40 CFR part 63. The data are acceptable if they meet 

the criteria specified in section 6.1.5 or section 6.3.3 of Method 301. If correction is required 

under section 6.3.3 of Method 301, the data are acceptable if the correction factor is within the 

range of 0.7 to 1.30. Other sections of Method 301 are not required.

(iii) Calculations. The average VOHAP concentration (C) on a mass-weighted basis shall be 

calculated by using the results for all samples analyzed in accordance with paragraph (b)(2)(ii) of 

this section and the following equation. An owner or operator using a test method that provides 

species-specific chemical concentrations may adjust the measured concentrations to the

corresponding concentration values which would be obtained had the off-site material samples 

been analyzed using Method 305. To adjust these data, the measured concentration for each 

individual HAP chemical species contained in the off-site material is multiplied by the 

appropriate species-specific adjustment factor (fm305) listed in Table 1 of this subpart. 

Where: 

C = Average VOHAP concentration of the off-site material at the point-of-delivery on a massweighted basis, ppmw.

i = Individual sample “i” of the off-site material.

n = Total number of samples of the off-site material collected (at least 4) for the averaging period 

(not to exceed 1 year). 

Qi = Mass quantity of off-site material stream represented by Ci, kg/hr. 

QT = Total mass quantity of off-site material during the averaging period, kg/hr. 

Ci = Measured VOHAP concentration of sample “i” as determined in accordance with the 

requirements of §63.694(a), ppmw.
(3) Knowledge of the off-site material to determine VOHAP concentration. 

(i) Documentation shall be prepared that presents the information used as the basis for the 

owner's or operator's knowledge of the off-site material stream's average VOHAP concentration. 

Examples of information that may be used as the basis for knowledge include: material balances 

for the source or process generating the off-site material stream; species-specific chemical test 

data for the off-site material stream from previous testing that are still applicable to the current 

off-site material stream; previous test data for other locations managing the same type of off-site 

material stream; or other knowledge based on information in documents such as manifests, 

shipping papers, or waste certification notices.

(ii) If test data are used as the basis for knowledge, then the owner or operator shall document 

the test method, sampling protocol, and the means by which sampling variability and analytical 

variability are accounted for in the determination of the average VOHAP concentration. For 

example, an owner or operator may use HAP concentration test data for the off-site material 

stream that are validated in accordance with Method 301 in 40 CFR part 63, appendix A of this 

part as the basis for knowledge of the off-site material. 

(iii) An owner or operator using species-specific chemical concentration test data as the basis for 

knowledge of the off-site material may adjust the test data to the corresponding average VOHAP 

concentration value which would be obtained had the off-site material samples been analyzed 

using Method 305. To adjust these data, the measured concentration for each individual HAP 

chemical species contained in the off-site material is multiplied by the appropriate speciesspecific adjustment factor (fm305) listed in Table 1 of this subpart. 

(iv) In the event that the Administrator and the owner or operator disagree on a determination of 

the average VOHAP concentration for an off-site material stream using knowledge, then the 

results from a determination of VOHAP concentration using direct measurement as specified in 

paragraph (b)(2) of this section shall be used to establish compliance with the applicable 

requirements of this subpart. The Administrator may perform or require that the owner or 

operator perform this determination using direct measurement. 

(c) Determination of average VOHAP concentration of an off-site material stream at the pointof-treatment.

(1) Sampling. Samples of the off-site material stream shall be collected at the point-of-treatment 

in a manner such that volatilization of organics contained in the sample is minimized and an 

adequately representative sample is collected and maintained for analysis by the selected 

method.

(i) The averaging period to be used for determining the average VOHAP concentration for the 

off-site material stream on a mass-weighted average basis shall be designated and recorded. The 

averaging period can represent any time interval that the owner or operator determines is 

appropriate for the off-site material stream but shall not exceed 1 year.
(ii) A sufficient number of samples, but no less than four samples, shall be collected to represent 

the complete range of HAP compositions and HAP quantities that occur in the off-site material 

stream during the entire averaging period due to normal variations in the operating conditions for 

the treatment process. Examples of such normal variations are seasonal variations in off-site 

material quantity or fluctuations in ambient temperature.

(iii) All samples shall be collected and handled in accordance with written procedures prepared 

by the owner or operator and documented in a site sampling plan. This plan shall describe the 

procedure by which representative samples of the off-site material stream are collected such that 

a minimum loss of organics occurs throughout the sample collection and handling process and by 

which sample integrity is maintained. A copy of the written sampling plan shall be maintained 

on-site in the plant site operating records. An example of an acceptable sampling plan includes a 

plan incorporating sample collection and handling procedures in accordance with the 

requirements specified in “Test Methods for Evaluating Solid Waste, Physical/Chemical 

Methods,” EPA Publication No. SW-846 or Method 25D in 40 CFR part 60, appendix A.

(2) Analysis. Each collected sample must be prepared and analyzed in accordance with one of the 

methods specified in paragraphs (b)(2)(ii)(A) through (b)(2)(ii)(I) of this section, as applicable to 

the sampled off-site material, for the purpose of measuring the HAP listed in Table 1 of this 

subpart.

(3) Calculations. The average VOHAP concentration (C̅ ) a mass-weighted basis shall be 

calculated by using the results for all samples analyzed in accordance with paragraph (c)(2) of 

this section and the following equation. An owner or operator using a test method that provides 

species-specific chemical concentrations may adjust the measured concentrations to the 

corresponding concentration values which would be obtained had the off-site material samples 

been analyzed using Method 305. To adjust these data, the measured concentration for each 

individual HAP chemical species contained in the off-site material is multiplied by the 

appropriate species-specific adjustment factor (fm305) listed in Table 1 of this subpart.

Where: 

C̅ = Average VOHAP concentration of the off-site material on a mass-weighted basis, ppmw.

i = Individual sample “i” of the off-site material.

n = Total number of samples of the off-site material collected (at least 4) for the averaging period 

(not to exceed 1 year).

Qi = Mass quantity of off-site material stream represented by Ci, kg/hr.

QT = Total mass quantity of off-site material during the averaging period, kg/hr.
Ci = Measured VOHAP concentration of sample “i” as determined in accordance with the 

requirements of §63.694(a), ppmw.

(d) Determination of treatment process VOHAP concentration limit (CR). (1) All of the off-site 

material streams entering the treatment process shall be identified. 

(2) The average VOHAP concentration of each off-site material stream at the point-of-delivery

shall be determined using the procedures specified in paragraph (b) of this section. 

(3) The VOHAP concentration limit (CR) shall be calculated by using the results determined for 

each individual off-site material stream and the following equation:

where:

CR=VOHAP concentration limit, ppmw. 

x=Individual off-site material stream “x” that has a VOHAP concentration less than 500 ppmw at 

the point-of-delivery. 

y=Individual off-site material stream “y” that has a VOHAP concentration equal to or greater 

than 500 ppmw at the point-of-delivery. 

m=Total number of “x” off-site material streams treated by process. 

n=Total number of “y” off-site material streams treated by process. 

Qx=Total mass quantity of off-site material stream “x”, kg/yr. 

Qy=Total mass quantity of off-site material stream “y”, kg/yr. 

C̅x=VOHAP concentration of off-site material stream “x” at the point-of-delivery, ppmw.

(e) Determination of required HAP mass removal rate (RMR).

(1) Each individual stream containing HAP that enters the treatment process shall be identified.

(2) The average VOHAP concentration at the point-of-delivery for each stream identified in 

paragraph (e)(1) of this section shall be determined using the test methods and procedures 

specified in paragraph (b) of this section.
(3) For each stream identified in paragraph (e)(1) of this section that has an average VOHAP 

concentration equal to or greater than 500 ppmw at the point-of-delivery, the average volumetric 

flow rate and the density of the off-site material stream at the point-of-delivery shall be 

determined.

(4) The required HAP mass removal rate (RMR) shall be calculated by using the average 

VOHAP concentration, average volumetric flow rate, and density determined in paragraph (e)(3) 

of this section for each stream and the following equation:

Where:

RMR = Required HAP mass removal rate, kg/hr.

y = Individual stream “y” that has a VOHAP concentration equal to or greater than 500 ppmw at 

the point-of-delivery as determined in §63.694(b).

n = Total number of “y” streams treated by process.

Vy = Average volumetric flow rate of stream “y” at the point-of-delivery, m3/hr.

ky = Density of stream “y”, kg/m3.

C̅y = Average VOHAP concentration of stream “y” at the point-of-delivery as determined in 

§63.694(b)(2), ppmw.

(f) Determination of actual HAP mass removal rate (MR).

(1) The actual HAP mass removal rate (MR) shall be determined based on results for a minimum 

of three consecutive runs. The sampling time for each run shall be at least 1 hour.

(2) The HAP mass flow entering the process (Eb) and the HAP mass flow exiting the process (Ea) 

shall be determined using the test methods and procedures specified in paragraphs (g)(2) through 

(g)(4) of this section.

(3) The actual mass removal rate shall be calculated using the HAP mass flow rates determined 

in paragraph (f)(2) of this section and the following equation:
MR = Eb−Ea

where:

MR = Actual HAP mass removal rate, kg/hr.

Eb = HAP mass flow entering process as determined in paragraph (f)(2) of this section, kg/hr.

Ea = HAP mass flow exiting process as determined in paragraph (f)(2) of this section, kg/hr.

(g) Determination of treatment process HAP reduction efficiency (R).

(1) The HAP reduction efficiency (R) for a treatment process shall be determined based on 

results for a minimum of three consecutive runs.

(2) Each individual stream containing HAP that enters the treatment process shall be identified. 

Each individual stream containing HAP that exits the treatment process shall be identified. The 

owner or operator shall prepare a sampling plan for measuring the identified streams that 

accurately reflects the retention time of the material in the process.

(3) For each run, information shall be determined for each stream identified in paragraph (g)(2) 

of this section as specified in paragraphs (g)(3)(i) through (g)(3)(iii) of this section.

(i) The mass quantity shall be determined for each stream identified in paragraph (g)(2) of this 

section as entering the process (Qb). The mass quantity shall be determined for each stream 

identified in paragraph (g)(2) of this section as exiting the process (Qa).

(ii) The average VOHAP concentration at the point-of-delivery shall be determined for each 

stream entering the process (Cb) (as identified in paragraph (g)(2) of this section) using the test 

methods and procedures specified in paragraph (b) of this section.

(iii) The average VOHAP concentration at the point-of-treatment shall be determined for each 

stream exiting the process (Ca) (as identified in paragraph (g)(2) of this section) using the test 

methods and procedures specified in paragraph (c) of this section.

(4) The HAP mass flow entering the process (Eb) and the HAP mass flow exiting the process (Ea) 

shall be calculated using the results determined in paragraph (g)(3) of this section and the 

following equations:

Where:
Eb = HAP mass flow entering process, kg/hr.

Ea = HAP mass flow exiting process, kg/hr.

m = Total number of runs (at least 3)

j = Individual run “j”

Qbj = Mass quantity of material entering process during run “j”, kg/hr.

Qaj = Average mass quantity of material exiting process during run “j”, kg/hr.

Caj = Average VOHAP concentration of material exiting process during run “j” as determined in 

§63.694(c), ppmw.

Cbj = Average VOHAP concentration of material entering process during run “j” as determined in 

§63.694(b)(2), ppmw.

(5) The HAP reduction efficiency (R) shall be calculated using the HAP mass flow rates 

determined in paragraph (g)(4) of this section and the following equation:

Where:

R = HAP reduction efficiency, percent.

Eb = HAP mass flow entering process as determined in paragraph (g)(4) of this section, kg/hr.

Ea = HAP mass flow exiting process as determined in accordance with the requirements of 

paragraph (g)(4) of this section, kg/hr.

(h) Determination of HAP biodegradation efficiency (Rbio).

(1) The fraction of HAP biodegraded (Fbio) shall be determined using one of the procedures 

specified in appendix C of this part 63.

(2) The HAP biodegradation efficiency (Rbio) shall be calculated by using the following equation:

Rbio−Fbio×100

where:

Rbio = HAP biodegradation efficiency, percent.
Fbio = Fraction of HAP biodegraded as determined in paragraph (h)(1) of this section.

(i) Determination of actual HAP mass removal rate (MRbio).

(1) The actual HAP mass removal rate (MRbio) shall be determined based on results for a 

minimum of three consecutive runs. The sampling time for each run shall be at least 1 hour.

(2) The HAP mass flow entering the process (Eb) shall be determined using the test methods and 

procedures specified in paragraphs (g)(2) through (g)(4) of this section.

(3) The fraction of HAP biodegraded (Fbio) shall be determined using the procedure specified in 

40 CFR part 63, appendix C of this part.

(4) The actual mass removal rate shall be calculated by using the HAP mass flow rates and 

fraction of HAP biodegraded determined in paragraphs (i)(2) and (i)(3), respectively, of this 

section and the following equation:

MRbio=Eb×Fbio

Where:

MRbio = Actual HAP mass removal rate, kg/hr.

Eb = HAP mass flow entering process, kg/hr.

Fbio = Fraction of HAP biodegraded.

(j) Determination of maximum HAP vapor pressure for off-site material in a tank. (1) The 

maximum HAP vapor pressure of the off-site material composition managed in a tank shall be 

determined using either direct measurement as specified in paragraph (j)(2) of this section or by 

knowledge of the off-site material as specified by paragraph (j)(3) of this section. 

(2) Direct measurement to determine the maximum HAP vapor pressure of an off-site material. 

(i) Sampling. A sufficient number of samples shall be collected to be representative of the offsite material contained in the tank. All samples shall be collected and handled in accordance with 

written procedures prepared by the owner or operator and documented in a site sampling plan. 

This plan shall describe the procedure by which representative samples of the off-site material is 

collected such that a minimum loss of organics occurs throughout the sample collection and 

handling process and by which sample integrity is maintained. A copy of the written sampling 

plan shall be maintained on-site in the plant site operating records. An example of an acceptable 

sampling plan includes a plan incorporating sample collection and handling procedures in 

accordance with the requirements specified in “Test Methods for Evaluating Solid Waste, 

Physical/Chemical Methods,” EPA Publication No. SW-846 or Method 25D in 40 CFR part 60, 

appendix A. 
(ii) Analysis. Any one of the following methods may be used to analyze the samples and 

compute the maximum HAP vapor pressure of the off-site material: 

(A) Method 25E in 40 CFR part 60 appendix A; 

(B) Methods described in American Petroleum Institute Bulletin 2517, “Evaporation Loss from 

External Floating Roof Tanks,”; 

(C) Methods obtained from standard reference texts; 

(D) ASTM Method 2879-83; or 

(E) Any other method approved by the Administrator. 

(3) Use of knowledge to determine the maximum HAP vapor pressure of the off-site material.

Documentation shall be prepared and recorded that presents the information used as the basis for 

the owner's or operator's knowledge that the maximum HAP vapor pressure of the off-site 

material is less than the maximum vapor pressure limit listed in Table 3,Table 4 or Table 5 of 

this subpart for the applicable tank design capacity category. Examples of information that may

be used include: the off-site material is generated by a process for which at other locations it 

previously has been determined by direct measurement that the off-site material maximum HAP 

vapor pressure is less than the maximum vapor pressure limit for the appropriate tank design 

capacity category. In the event that the Administrator and the owner or operator disagree on a 

determination of the maximum HAP vapor pressure for an off-site material stream using 

knowledge, then the results from a determination of HAP vapor pressure using direct 

measurement as specified in paragraph (j)(2) of this section shall be used to establish compliance 

with the applicable requirements of this subpart. The Administrator may perform or require that 

the owner or operator perform this determination using direct measurement.

(k) Procedure for determining no detectable organic emissions for the purpose of complying with 

this subpart.

(1) The test shall be conducted in accordance with the procedures specified in Method 21 of 40 

CFR part 60, appendix A. Each potential leak interface (i.e., a location where organic vapor 

leakage could occur) on the cover and associated closure devices shall be checked. Potential leak 

interfaces that are associated with covers and closure devices include, but are not limited to: the 

interface of the cover and its foundation mounting; the periphery of any opening on the cover 

and its associated closure device; and the sealing seat interface on a spring-loaded pressure relief 

valve.

(2) The test shall be performed when the unit contains a material having a total organic 

concentration representative of the range of concentrations for the materials expected to be 

managed in the unit. During the test, the cover and closure devices shall be secured in the closed 

position.
(3) The detection instrument shall meet the performance criteria of Method 21 of 40 CFR part 

60, appendix A, except the instrument response factor criteria in section 8.1.1 of Method 21 shall 

be for the weighted average composition of the organic constituents in the material placed in the 

unit at the time of monitoring, not for each individual organic constituent.

(4) The detection instrument shall be calibrated before use on each day of its use by the 

procedures specified in Method 21 of 40 CFR part 60, appendix A.

(5) Calibration gases shall be as follows:

(i) Zero air (less than 10 ppmv hydrocarbon in air); and

(ii) A mixture of methane or n-hexane in air at a concentration of approximately, but less than, 

10,000 ppmv.

(6) An owner or operator may choose to adjust or not adjust the detection instrument readings to 

account for the background organic concentration level. If an owner or operator chooses to adjust 

the instrument readings for the background level, the background level value must be determined 

according to the procedures in Method 21 of 40 CFR part 60, appendix A.

(7) Each potential leak interface shall be checked by traversing the instrument probe around the 

potential leak interface as close to the interface as possible, as described in Method 21. In the 

case when the configuration of the cover or closure device prevents a complete traverse of the 

interface, all accessible portions of the interface shall be sampled. In the case when the 

configuration of the closure device prevents any sampling at the interface and the device is 

equipped with an enclosed extension or horn (e.g., some pressure relief devices), the instrument

probe inlet shall be placed at approximately the center of the exhaust area to the atmosphere.

(8) An owner or operator must determine if a potential leak interface operates with no detectable 

emissions using the applicable procedure specified in paragraph (k)(8)(i) or (k)(8)(ii) of this 

section.

(i) If an owner or operator chooses not to adjust the detection instrument readings for the 

background organic concentration level, then the maximum organic concentration value 

measured by the detection instrument is compared directly to the applicable value for the 

potential leak interface as specified in paragraph (k)(9) of this section.

(ii) If an owner or operator chooses to adjust the detection instrument readings for the 

background organic concentration level, the value of the arithmetic difference between the 

maximum organic concentration value measured by the instrument and the background organic 

concentration value as determined in paragraph (k)(6) of this section is compared with the 

applicable value for the potential leak interface as specified in paragraph (k)(9) of this section.

(9) A potential leak interface is determined to operate with no detectable emissions using the 

applicable criteria specified in paragraphs (k)(9)(i) and (k)(9)(ii) of this section.
(i) For a potential leak interface other than a seal around a shaft that passes through a cover 

opening, the potential leak interface is determined to operate with no detectable organic 

emissions if the organic concentration value determined in paragraph (k)(8) is less than 500 

ppmv.

(ii) For a seal around a shaft that passes through a cover opening, the potential leak interface is 

determined to operate with no detectable organic emissions if the organic concentration value 

determined in paragraph (k)(8) is less than 10,000 ppmv.

(l) Control device performance test procedures. Performance tests shall be based on 

representative performance (i.e., performance based on normal operating conditions) and shall 

exclude periods or startup and shutdown unless specified by the Administrator. The owner or 

operator may not conduct performance tests during periods of malfunction. The owner or 

operator must record the process information that is necessary to document operating conditions 

during the test and include in such record an explanation to support that such conditions 

represent normal operation. Upon request, the owner or operator shall make available to the 

Administrator such records as may be necessary to determine the conditions of performance 

tests.

(1) Method 1 or 1A of 40 CFR part 60, appendix A, as appropriate, shall be used for selection of 

the sampling sites at the inlet and outlet of the control device. 

(i) To determine compliance with a control device percent reduction requirement, sampling sites 

shall be located at the inlet of the control device as specified in paragraphs (l)(1)(i)(A) and 

(l)(1)(i)(B) of this section, and at the outlet of the control device. 

(A) The control device inlet sampling site shall be located after the final product recovery device. 

(B) If a vent stream is introduced with the combustion air or as an auxiliary fuel into a boiler or 

process heater, the location of the inlet sampling sites shall be selected to ensure that the 

measurement of total HAP concentration or TOC concentration, as applicable, includes all vent 

streams and primary and secondary fuels introduced into the boiler or process heater. 

(ii) To determine compliance with an enclosed combustion device concentration limit, the 

sampling site shall be located at the outlet of the device. 

(2) The gas volumetric flow rate shall be determined using Method 2, 2A, 2C, 2D, 2F, or 2G of 

40 CFR part 60, appendix A, as appropriate. 

(3) To determine compliance with the control device percent reduction requirement, the owner or 

operator shall use Method 18 of 40 CFR part 60, appendix A to measure the HAP in Table 1 of 

this subpart or Method 25A of 40 CFR 60, appendix A to measure TOC. Method 18 may be used 

to measure methane and ethane, and the measured concentration may be subtracted from the 

Method 25A measurement. Alternatively, any other method or data that has been validated 

according to the applicable procedures in Method 301 in 40 CFR part 63, appendix A may be 

used. The following procedures shall be used to calculate percent reduction efficiency: 
(i) A minimum of three sample runs must be performed. The minimum sampling time for each 

run shall be 1 hour. For Method 18, either an integrated sample or a minimum of four grab 

samples shall be taken. If grab sampling is used, then the samples shall be taken at approximately

equal intervals in time such as 15 minute intervals during the run. 

(ii) The mass rate of either TOC (minus methane and ethane) or total HAP (Ei and Eo

,respectively) shall be computed. 

(A) The following equations shall be used: 

Where: 

Cij, Coj = Concentration of sample component j of the gas stream at the inlet and outlet of the 

control device, respectively, dry basis, parts per million by volume. 

Ei, Eo = Mass rate of TOC (minus methane and ethane) or total HAP at the inlet and outlet of the 

control device, respectively, dry basis, kilogram per hour. 

Mij, Moj = Molecular weight of sample component j of the gas stream at the inlet and outlet of the 

control device, respectively, gram/gram-mole. 

Qi, Qo = Flow rate of gas stream at the inlet and outlet of the control device, respectively, dry 

standard cubic meter per minute. 

K2 = Constant, 2.494×10−6 (parts per million)−1 (gram-mole per standard cubic meter) 

(kilogram/gram) (minute/hour), where standard temperature (gram-mole per standard cubic 

meter) is 20 °C.

(B) When the TOC mass rate is calculated, the average concentration reading (minus methane 

and ethane) measured by Method 25A of 40 CFR part 60, appendix A shall be used in the 

equation in paragraph (l)(3)(ii)(A) of this section. 

(C) When the total HAP mass rate is calculated, only the HAP constituents shall be summed 

using the equation in paragraph (l)(3)(ii)(A) of this section. 

(iii) The percent reduction in TOC (minus methane and ethane) or total HAP shall be calculated 

as follows: 
where: 

Rcd=Control efficiency of control device, percent. 

Ei=Mass rate of TOC (minus methane and ethane) or total HAP at the inlet to the control device 

as calculated under paragraph (l)(3)(ii) of this section, kilograms TOC per hour or kilograms

HAP per hour. 

Eo=Mass rate of TOC (minus methane and ethane) or total HAP at the outlet of the control 

device, as calculated under paragraph (l)(3)(ii) of this section, kilograms TOC per hour or 

kilograms HAP per hour.

(iv) If the vent stream entering a boiler or process heater is introduced with the combustion air or 

as a secondary fuel, the weight-percent reduction of total HAP or TOC (minus methane and 

ethane) across the device shall be determined by comparing the TOC (minus methane and 

ethane) or total HAP in all combusted vent streams and primary and secondary fuels with the 

TOC (minus methane and ethane) or total HAP exiting the device, respectively. 

(4) To determine compliance with the enclosed combustion device total HAP concentration limit 

of this subpart, the owner or operator shall use Method 18 of 40 CFR part 60, appendix A to 

measure the total HAP in Table 1 of this subpart or Method 25A of 40 CFR part 60, appendix A 

to measure TOC. Method 18 may be used to measure methane and ethane and the measured 

concentration may be subtracted from the Method 25A measurement. Alternatively, any other 

method or data that has been validated according to Method 301 in appendix A of this part, may

be used. The following procedures shall be used to calculate parts per million by volume 

concentration, corrected to 3 percent oxygen: 

(i) A minimum of three sample runs must be performed. The minimum sampling time for each 

run shall be 1 hour. For Method 18, either an integrated sample or a minimum of four grab 

samples shall be taken. If grab sampling is used, then the samples shall be taken at approximately

equal intervals in time, such as 15 minute intervals during the run. 

(ii) The TOC concentration or total HAP concentration shall be calculated according to 

paragraph (m)(4)(ii)(A) or (m)(4)(ii)(B) of this section. 

(A) The TOC concentration (CTOC) is the average concentration readings provided by Method 

25A of 40 CFR part 60, appendix A, minus the concentration of methane and ethane.

(B) The total HAP concentration (CHAP) shall be computed according to the following equation:

 = 

∑ 










where:

CHAP = Total concentration of HAP compounds listed in Table 1 of this subpart, dry basis, parts 

per million by volume.

Cij = Concentration of sample components j of sample i, dry basis, parts per million by volume.

n = Number of components in the sample.

x = Number of samples in the sample run.

(iii) The measured TOC concentration or total HAP concentration shall be corrected to 3 percent 

oxygen as follows: 

(A) The emission rate correction factor or excess air, integrated sampling and analysis 

procedures of Method 3B of 40 CFR part 60, appendix A shall be used to determine the oxygen 

concentration (%O2dry). Alternatively, the owner or operator may use Method 3A of 40 CFR part 

60, appendix A to determine the oxygen concentration. The samples shall be collected during the 

same time that the samples are collected for determining TOC concentration or total HAP 

concentration. 

(B) The concentration corrected to 3 percent oxygen (Cc) shall be computed using the following 

equation: 

where:

Cc=TOC concentration or total HAP concentration corrected to 3 percent oxygen, dry basis, parts 

per million by volume. 

Cm=Measured TOC concentration or total HAP concentration, dry basis, parts per million by

volume. 

%O2dry=Concentration of oxygen, dry basis, percent by volume.

(m) Determination of process vent stream flow rate and total HAP concentration.

(1) Method 1 or 1A of 40 CFR part 60, appendix A, as appropriate, must be used for selection of 

the sampling site.
(2) No traverse site selection method is needed for vents smaller than 0.10 meter in diameter. For 

vents smaller than 0.10 meter in diameter, sample at the center of the vent.

(3) Process vent stream gas volumetric flow rate must be determined using Method 2, 2A, 2C, 

2D, 2F, or 2G of 40 CFR part 60, appendix A, as appropriate.

(4) Process vent stream total HAP concentration must be measured using the following 

procedures:

(i) Method 18 of 40 CFR part 60, appendix A, must be used to measure the total HAP 

concentration. Alternatively, any other method or data that has been validated according to the 

protocol in Method 301 of appendix A of this part may be used.

(ii) Where Method 18 of 40 CFR part 60, appendix A, is used, the following procedures must be 

used to calculate parts per million by volume concentration:

(A) The minimum sampling time for each run must be 1 hour in which either an integrated 

sample or four grab samples must be taken. If grab sampling is used, then the samples must be 

taken at approximately equal intervals in time, such as 15 minute intervals during the run.

(B) The total HAP concentration (CHAP) must be computed according to the following equation:

Where:

CHAP = Total concentration of HAP compounds listed in Table 1 of this subpart, dry basis, parts 

per million by volume.

Cji = Concentration of sample component j of the sample i, dry basis, parts per million by

volume.

n = Number of components in the sample.

x = Number of samples in the sample run.

§63.695 Inspection and monitoring requirements.

(a) The owner or operator must install, calibrate, maintain, and operate all monitoring system 

components according to §§ 63.8 of this part, 63.684(e), 63.693(d)(3), (e)(3), (f)(3), (g)(3), and

(h)(3) of this subpart, and paragraph (5) of this section and perform the inspection and 

monitoring procedures specified in paragraphs (a)(1) through (4) of this section.
(1) To inspect tank fixed roofs and floating roofs for compliance with the Tank Level 2 controls 

standards specified in §63.685 of this subpart, the inspection procedures are specified in 

paragraph (b) of this section.

(2) To inspect and monitor closed-vent systems for compliance with the standards specified in 

§63.693 of this subpart, the inspection and monitoring procedures are specified in paragraph (c) 

of this section.

(3) To inspect and monitor transfer system covers for compliance with the standards specified in 

§63.689(c)(1) of this subpart, the inspection and monitoring procedures are specified in 

paragraph (d) of this section.

(4) To monitor and record off-site material treatment processes for compliance with the 

standards specified in 63.684(e), the monitoring procedures are specified in paragraph (e) of this 

section.

(5)(i) Except for periods of monitoring system malfunctions, repairs associated with monitoring 

system malfunctions and required monitoring system quality assurance or quality control 

activities (including, as applicable, calibration checks and required zero and span adjustments), 

the owner or operator must operate the continuous monitoring system at all times the affected 

source is operating. A monitoring system malfunction is any sudden, infrequent, not reasonably 

preventable failure of the monitoring system to provide data. Monitoring system failures that are 

caused in part by poor maintenance or careless operation are not malfunctions. The owner or 

operator is required to complete monitoring system repairs in response to monitoring system 

malfunctions and to return the monitoring system to operation as expeditiously as practicable.

(ii) The owner or operator may not use data recorded during monitoring system malfunctions, 

repairs associated with monitoring system malfunctions, or required monitoring system quality 

assurance or control activities in calculations used to report emissions or operating levels. The 

owner or operator must use all the data collected during all other required data collection periods 

in assessing the operation of the control device and associated control system. The owner or 

operator must report any periods for which the monitoring system failed to collect required data.

(b) Tank Level 2 fixed roof and floating roof inspection requirements.

(1) Owners and operators that use a tank equipped with an internal floating roof in accordance 

with the provisions of §63.685(e) of this subpart shall meet the following inspection 

requirements:

(i) The floating roof and its closure devices shall be visually inspected by the owner or operator 

to check for defects that could result in air emissions. Defects include, but are not limited to, the 

internal floating roof is not floating on the surface of the liquid inside the tank; liquid has 

accumulated on top of the internal floating roof; any portion of the roof seals have detached from 

the roof rim; holes, tears, or other openings are visible in the seal fabric; the gaskets no longer 

close off the waste surfaces from the atmosphere; or the slotted membrane has more than 10 

percent open area.
(ii) The owner or operator shall inspect the internal floating roof components as follows except 

as provided for in paragraph (b)(1)(iii) of this section:

(A) Visually inspect the internal floating roof components through openings on the fixed-roof 

(e.g., manholes and roof hatches) at least once every calendar year after initial fill, and

(B) Visually inspect the internal floating roof, primary seal, secondary seal (if one is in service), 

gaskets, slotted membranes, and sleeve seals (if any) each time the tank is emptied and degassed 

and at least every 10 years. Prior to each inspection, the owner or operator shall notify the 

Administrator in accordance with the reporting requirements specified in §63.697 of this subpart.

(iii) As an alternative to performing the inspections specified in paragraph (b)(1)(ii) of this 

section for an internal floating roof equipped with two continuous seals mounted one above the 

other, the owner or operator may visually inspect the internal floating roof, primary and 

secondary seals, gaskets, slotted membranes, and sleeve seals (if any) each time the tank is 

emptied and degassed and at least every 5 years. Prior to each inspection, the owner or operator 

shall notify the Administrator in accordance with the reporting requirements specified in §63.697 

of this subpart.

(iv) In the event that a defect is detected, the owner or operator shall repair the defect in 

accordance with the requirements of paragraph (b)(4) of this section.

(v) The owner or operator shall maintain a record of the inspection in accordance with the 

requirements specified in §63.696 of this subpart.

(2) Owners and operators that use a tank equipped with an external floating roof in accordance 

with the provisions of §63.685(f) of this subpart shall meet the following requirements:

(i) The owner or operator shall measure the external floating roof seal gaps in accordance with 

the following requirements:

(A) The owner or operator shall perform measurements of gaps between the tank wall and the 

primary seal within 60 days after initial operation of the tank following installation of the 

floating roof and, thereafter, at least once every 5 years. Prior to each inspection, the owner or 

operator shall notify the Administrator in accordance with the reporting requirements specified in 

§63.697 of this subpart.

(B) The owner or operator shall perform measurements of gaps between the tank wall and the 

secondary seal within 60 days after initial operation of the separator following installation of the 

floating roof and, thereafter, at least once every year. Prior to each inspection, the owner or 

operator shall notify the Administrator in accordance with the reporting requirements specified in 

§63.697 of this subpart.

(C) If a tank ceases to hold off-site material for a period of 1 year or more, subsequent 

introduction of off-site material into the tank shall be considered an initial operation for the 

purposes of paragraphs (b)(2)(i)(A) and (b)(2)(i)(B) of this section.
(D) The owner shall determine the total surface area of gaps in the primary seal and in the 

secondary seal individually using the following procedure.

(1) The seal gap measurements shall be performed at one or more floating roof levels when the 

roof is floating off the roof supports.

(2) Seal gaps, if any, shall be measured around the entire perimeter of the floating roof in each 

place where a 0.32-centimeter (cm) (1⁄8 -inch) diameter uniform probe passes freely (without 

forcing or binding against the seal) between the seal and the wall of the tank and measure the 

circumferential distance of each such location.

(3) For a seal gap measured under paragraph (b)(2) of this section, the gap surface area shall be 

determined by using probes of various widths to measure accurately the actual distance from the 

tank wall to the seal and multiplying each such width by its respective circumferential distance.

(4) The total gap area shall be calculated by adding the gap surface areas determined for each 

identified gap location for the primary seal and the secondary seal individually, and then dividing

the sum for each seal type by the nominal diameter of the tank. These total gap areas for the 

primary seal and secondary seal are then compared to the respective standards for the seal type as 

specified in §63.685(f)(1) of this subpart.

(E) In the event that the seal gap measurements do not conform to the specifications in 

§63.685(f)(1) of this subpart, the owner or operator shall repair the defect in accordance with the 

requirements of paragraph (b)(4) of this section.

(F) The owner or operator shall maintain a record of the inspection in accordance with the 

requirements specified in §63.696 of this subpart.

(ii) The owner or operator shall visually inspect the external floating roof in accordance with the 

following requirements:

(A) The floating roof and its closure devices shall be visually inspected by the owner or operator 

to check for defects that could result in air emissions. Defects include, but are not limited to: 

holes, tears, or other openings in the rim seal or seal fabric of the floating roof; a rim seal 

detached from the floating roof; all or a portion of the floating roof deck being submerged below 

the surface of the liquid in the tank; broken, cracked, or otherwise damaged seals or gaskets on 

closure devices; and broken or missing hatches, access covers, caps, or other closure devices.

(B) The owner or operator shall perform the inspections following installation of the external 

floating roof and, thereafter, at least once every year.

(C) In the event that a defect is detected, the owner or operator shall repair the defect in 

accordance with the requirements of paragraph (b)(4) of this section.

(D) The owner or operator shall maintain a record of the inspection in accordance with the 

requirements specified in §63.696(d) of this subpart.
(3) Owners and operators that use a tank equipped with a fixed roof in accordance with the 

provisions of §63.685(g) of this subpart shall meet the following requirements:

(i) The fixed roof and its closure devices shall be visually inspected by the owner or operator to 

check for defects that could result in air emissions. Defects include, but are not limited to, visible 

cracks, holes, or gaps in the roof sections or between the roof and the separator wall; broken, 

cracked, or otherwise damaged seals or gaskets on closure devices; and broken or missing 

hatches, access covers, caps, or other closure devices. In the case when a tank is buried partially

or entirely underground, inspection is required only for those portions of the cover that extend to 

or above the ground surface, and those connections that are on such portions of the cover (e.g., 

fill ports, access hatches, gauge wells, etc.) and can be opened to the atmosphere.

(ii) The owner or operator must perform an initial inspection following installation of the fixed 

roof. Thereafter, the owner or operator must perform the inspections at least once every calendar 

year except as provided for in paragraph (f) of this section.

(iii) In the event that a defect is detected, the owner or operator shall repair the defect in 

accordance with the requirements of paragraph (b)(4) of this section.

(iv) The owner or operator shall maintain a record of the inspection in accordance with the 

requirements specified in §63.696(e) of this subpart.

(4) The owner or operator shall repair each defect detected during an inspection performed in 

accordance with the requirements of paragraph (b)(1), (b)(2), or (b)(3) of this section in the 

following manner:

(i) The owner or operator shall within 45 calendar days of detecting the defect either repair the 

defect or empty the tank and remove it from service. If within this 45-day period the defect 

cannot be repaired or the tank cannot be removed from service without disrupting operations at 

the plant site, the owner or operator is allowed two 30-day extensions. In cases when an owner or 

operator elects to use a 30-day extension, the owner or operator shall prepare and maintain 

documentation describing the defect, explaining why alternative storage capacity is not available, 

and specify a schedule of actions that will ensure that the control equipment will be repaired or 

the tank emptied as soon as possible.

(ii) When a defect is detected during an inspection of a tank that has been emptied and degassed, 

the owner or operator shall repair the defect before refilling the tank.

(c) Owners and operators that use a closed-vent system in accordance with the provisions of 

§63.693 of this subpart shall meet the following inspection and monitoring requirements:

(1) Each closed-vent system that is used to comply with §63.693(c)(1)(i) of this subpart shall be 

inspected and monitored in accordance with the following requirements:
(i) At initial startup, the owner or operator shall monitor the closed-vent system components and 

connections using the procedures specified in §63.694(k) of this subpart to demonstrate that the 

closed-vent system operates with no detectable organic emissions.

(ii) After initial startup, the owner or operator shall inspect and monitor the closed-vent system 

as follows:

(A) Closed-vent system joints, seams, or other connections that are permanently or semipermanently sealed (e.g., a welded joint between two sections of hard piping or a bolted and 

gasketed ducting flange) shall be visually inspected at least once per year to check for defects 

that could result in air emissions. The owner or operator shall monitor a component or 

connection using the procedures specified in §63.694(k) of this subpart to demonstrate that it 

operates with no detectable organic emissions following any time the component is repaired or 

replaced (e.g., a section of damaged hard piping is replaced with new hard piping) or the 

connection is unsealed (e.g., a flange is unbolted).

(B) Closed-vent system components or connections other than those specified in paragraph 

(c)(1)(ii)(A) of this section, shall be monitored at least once per year using the procedures 

specified in §63.694(k) of this subpart to demonstrate that components or connections operate 

with no detectable organic emissions.

(C) The continuous monitoring system required by §63.693(b)(4)(i) shall monitor and record 

either an instantaneous data value at least once every 15 minutes or an average value for intervals 

of 15 minutes or less.

(D) The owner or operator shall visually inspect the seal or closure mechanism required by

§63.693(c)(2)(ii) at least once every month to verify that the bypass mechanism is maintained in 

the closed position. 

(iii) In the event that a defect or leak is detected, the owner or operator shall repair the defect or 

leak in accordance with the requirements of paragraph (c)(3) of this section.

(iv) The owner or operator shall maintain a record of the inspection and monitoring in 

accordance with the requirements specified in §63.696 of this subpart.

(2) Each closed-vent system that is used to comply with §63.693(c)(1)(ii) of this subpart shall be 

inspected and monitored in accordance with the following requirements:

(i) The closed-vent system shall be visually inspected by the owner or operator to check for 

defects that could result in air emissions. Defects include, but are not limited to, visible cracks, 

holes, or gaps in ductwork or piping; loose connections; or broken or missing caps or other 

closure devices.

(ii) The owner or operator must perform an initial inspection following installation of the closedvent system. Thereafter, the owner or operator must perform the inspections at least once every

calendar year except as provided for in paragraph (f) of this section.
(iii) In the event that a defect is detected, the owner or operator shall repair the defect in 

accordance with the requirements of paragraph (c)(3) of this section.

(iv) The owner or operator shall maintain a record of the inspection in accordance with the 

requirements specified in §63.696 of this subpart.

(3) The owner or operator shall repair all detected defects as follows:

(i) The owner or operator shall make first efforts at repair of the defect no later than 5 calendar 

days after detection and repair shall be completed as soon as possible but no later than 45

calendar days after detection.

(ii) Repair of a defect may be delayed beyond 45 calendar days if either of the conditions 

specified in paragraph (c)(3)(ii)(A) or (c)(3)(ii)(B) occurs. In this case, the owner or operator 

must repair the defect the next time the process or unit that vents to the closed-vent system is 

shutdown. Repair of the defect must be completed before the process or unit resumes operation.

(A) Completion of the repair is technically infeasible without the shutdown of the process or unit 

that vents to the closed-vent system.

(B) The owner or operator determines that the air emissions resulting from the repair of the 

defect within the specified period would be greater than the fugitive emissions likely to result by

delaying the repair until the next time the process or unit that vents to the closed-vent system is 

shutdown.

(iii) The owner or operator shall maintain a record of the defect repair in accordance with the 

requirements specified in §63.696 of this subpart.

(d) Owners and operators that use a transfer system equipped with a cover in accordance with the 

provisions of §63.689(c)(1) of this subpart shall meet the following inspection requirements:

(1) The cover and its closure devices shall be visually inspected by the owner or operator to 

check for defects that could result in air emissions. Defects include, but are not limited to, visible 

cracks, holes, or gaps in the cover sections or between the cover and its mounting; broken, 

cracked, or otherwise damaged seals or gaskets on closure devices; and broken or missing 

hatches, access covers, caps, or other closure devices. In the case when a transfer system is 

buried partially or entirely underground, inspection is required only for those portions of the 

cover that extend to or above the ground surface, and those connections that are on such portions 

of the cover (e.g., access hatches, etc.) and can be opened to the atmosphere.

(2) The owner or operator must perform an initial inspection following installation of the cover. 

Thereafter, the owner or operator must perform the inspections at least once every calendar year 

except as provided for in paragraph (f) of this section.

(3) In the event that a defect is detected, the owner or operator shall repair the defect in 

accordance with the requirements of paragraph (d)(5) of this section.
(4) The owner or operator shall maintain a record of the inspection in accordance with the 

requirements specified in §63.696 of this subpart.

(5) The owner or operator shall repair all detected defects as follows:

(i) The owner or operator shall make first efforts at repair of the defect no later than 5 calendar 

days after detection and repair shall be completed as soon as possible but no later than 45 

calendar days after detection except as provided in paragraph (d)(5)(ii) of this section.

(ii) Repair of a defect may be delayed beyond 45 calendar days if the owner or operator 

determines that repair of the defect requires emptying or temporary removal from service of the 

transfer system and no alternative transfer system is available at the site to accept the material 

normally handled by the system. In this case, the owner or operator shall repair the defect the 

next time the process or unit that is generating the material handled by the transfer system stops

operation. Repair of the defect must be completed before the process or unit resumes operation.

(iii) The owner or operator shall maintain a record of the defect repair in accordance with the 

requirements specified in §63.696 of this subpart.

(e) Control device monitoring requirements. For each control device required under § 63.693 of 

this subpart to be monitored in accordance with the provisions of this paragraph (e), the owner or 

operator must ensure that each control device operates properly by monitoring the control device 

in accordance with the requirements specified in paragraphs (e)(1) through (e)(5) of this section.

(1) A continuous parameter monitoring system must be used to measure the operating parameter 

or parameters specified for the control device in §63.693(d) through §63.693(g) of this subpart as 

applicable to the type and design of the control device. The continuous parameter monitoring 

system must meet the following specifications and requirements:

(i) The continuous parameter monitoring system must measure either an instantaneous value at 

least once every 15 minutes or an average value for intervals of 15 minutes or less and 

continuously record either:

(A) Each measured data value; or

(B) Each block average value for each 1-hour period or shorter periods calculated from all 

measured data values during each period. If values are measured more frequently than once per 

minute, a single value for each minute may be used to calculate the hourly (or shorter period) 

block average instead of all measured values.

(ii) The monitoring system must be installed, calibrated, operated, and maintained in accordance 

with the manufacturer's specifications or other written procedures that provide reasonable 

assurance that the monitoring equipment is operating properly.

(2) Using the data recorded by the monitoring system, the owner or operator must calculate the 

daily average value for each monitored operating parameter for each operating day. If operation 
of the control device is continuous, the operating day is a 24-hour period. If control device 

operation is not continuous, the operating day is the total number of hours of control device 

operation per 24-hour period. Valid data points must be available for 75 percent of the operating 

hours in an operating day to compute the daily average.

(3) For each monitored operating parameter, the owner or operator must establish a minimum 

operating parameter value or a maximum operating parameter value, as appropriate, to define the 

range of conditions at which the control device must be operated to continuously achieve the 

applicable performance requirements specified in §63.693(b)(2) of this subpart. Each minimum 

or maximum operating parameter value must be established in accordance with the requirements 

in paragraphs (e)(3)(i) and (e)(3)(ii) of this section.

(i) If the owner or operator conducts a performance test to demonstrate control device 

performance, then the minimum or maximum operating parameter value must be established 

based on values measured during the performance test and supplemented, as necessary, by the 

control device design specifications, manufacturer recommendations, or other applicable 

information.

(ii) If the owner or operator uses a control device design analysis to demonstrate control device 

performance, then the minimum or maximum operating parameter value must be established 

based on the control device design analysis and supplemented, as necessary, by the control 

device manufacturer recommendations or other applicable information.

(4) A deviation for a given control device is determined to have occurred when the monitoring 

data or lack of monitoring data result in any one of the criteria specified in paragraphs (e)(4)(i) 

through (e)(4)(iii) of this section being met. When multiple operating parameters are monitored 

for the same control device and during the same operating day more than one of these operating 

parameters meets a deviation criterion specified in paragraphs (e)(4)(i) through (e)(4)(iii) of this 

section, then a single deviation is determined to have occurred for the control device for that 

operating day.

(i) A deviation occurs when the daily average value of a monitored operating parameter is less 

than the minimum operating parameter limit (or, if applicable, greater than the maximum 

operating parameter limit) established for the operating parameter in accordance with the 

requirements of paragraph (e)(3) of this section.

(ii) A deviation occurs when the period of control device operation is 4 hours or greater in an 

operating day and the monitoring data are insufficient to constitute a valid hour of data for at 

least 75 percent of the operating hours. Monitoring data are insufficient to constitute a valid hour 

of data if measured values are unavailable for any of the 15-minute periods within the hour.

(iii) A deviation occurs when the period of control device operation is less than 4 hours in an 

operating day and more than 1 of the hours during the period does not constitute a valid hour of 

data due to insufficient monitoring data. Monitoring data are insufficient to constitute a valid 

hour of data if measured values are unavailable for any of the 15-minute periods within the hour.
(5) For each deviation, except when the deviation occurs during periods of non-operation of the 

unit or the process that is vented to the control device (resulting in cessation of HAP emissions to 

which the monitoring applies), the owner or operator shall be deemed to have failed to have 

applied control in a manner that achieves the required operating parameter limits. Failure to 

achieve the required operating parameter limits is a violation of this standard.

(f) Alternative inspection and monitoring interval. Following the initial inspection and 

monitoring of a piece of air pollution control equipment in accordance with the applicable 

provisions of this section, subsequent inspection and monitoring of the equipment may be 

performed at intervals longer than 1 year when an owner or operator determines that performing 

the required inspection or monitoring procedures would expose a worker to dangerous, 

hazardous, or otherwise unsafe conditions and the owner or operator complies with the 

requirements specified in paragraphs (f)(1) and (f)(2) of this section.

(1) The owner or operator must prepare and maintain at the plant site written documentation 

identifying the specific air pollution control equipment designated as “unsafe to inspect and 

monitor.” The documentation must include for each piece of air pollution control equipment 

designated as such a written explanation of the reasons why the equipment is unsafe to inspect or 

monitor using the applicable procedures under this section.

(2) The owner or operator must develop and implement a written plan and schedule to inspect 

and monitor the air pollution control equipment using the applicable procedures specified in this 

section during times when a worker can safely access the air pollution control equipment. The 

required inspections and monitoring must be performed as frequently as practicable but do not 

need to be performed more frequently than the periodic schedule that would be otherwise 

applicable to the air pollution control equipment under the provisions of this section. A copy of 

the written plan and schedule must be maintained at the plant site.

§63.696 Recordkeeping requirements.

(a) The owner or operator subject to this subpart shall comply with the recordkeeping 

requirements in §63.10 under 40 CFR 63 subpart A—General Provisions that are applicable to 

this subpart as specified in Table 2 of this subpart. 

(b) The owner or operator of a control device subject to this subpart shall maintain the records in 

accordance with the requirements of 40 CFR 63.10 of this part. 

(c) [Reserved] 

(d) Each owner or operator using an internal floating roof to comply with the tank control 

requirements specified in §63.685(e) of this subpart or using an external floating roof to comply
with the tank control requirements specified in §63.685(f) of this subpart shall prepare and 

maintain the following records: 

(1) Documentation describing the floating roof design and the dimensions of the tank. 

(2) A record for each inspection required by §63.695(b) of this subpart, as applicable to the tank, 

that includes the following information: a tank identification number (or other unique 

identification description as selected by the owner or operator) and the date of inspection. 

(3) The owner or operator shall record for each defect detected during inspections required by

§63.695(b) of this subpart the following information: the location of the defect, a description of 

the defect, the date of detection, and corrective action taken to repair the defect. In the event that 

repair of the defect is delayed in accordance with the provisions of §63.695(b)(4) of this section, 

the owner or operator shall also record the reason for the delay and the date that completion of 

repair of the defect is expected. 

(4) Owners and operators that use a tank equipped with an external floating roof in accordance 

with the provisions of §63.685(f) of this subpart shall prepare and maintain records for each seal 

gap inspection required by §63.695(b) describing the results of the seal gap measurements. The 

records shall include the date of that the measurements are performed, the raw data obtained for 

the measurements, and the calculations of the total gap surface area. In the event that the seal gap 

measurements do not conform to the specifications in §63.695(b) of this subpart, the records 

shall include a description of the repairs that were made, the date the repairs were made, and the 

date the separator was emptied, if necessary. 

(e) Each owner or operator using a fixed roof to comply with the tank control requirements 

specified in §63.685(g) of this subpart shall prepare and maintain the following records: 

(1) A record for each inspection required by §63.695(b) of this subpart, as applicable to the tank, 

that includes the following information: a tank identification number (or other unique 

identification description as selected by the owner or operator) and the date of inspection. 

(2) The owner or operator shall record for each defect detected during inspections required by 

§63.695(b) of this subpart the following information: the location of the defect, a description of 

the defect, the date of detection, and corrective action taken to repair the defect. In the event that 

repair of the defect is delayed in accordance with the provisions of §63.695(b)(4) of this section, 

the owner or operator shall also record the reason for the delay and the date that completion of 

repair of the defect is expected. 

(f) Each owner or operator using an enclosure to comply with the tank control requirements 

specified in §63.685(i) of this subpart shall prepare and maintain records for the most recent set 

of calculations and measurements performed by the owner or operator to verify that the 

enclosure meets the criteria of a permanent total enclosure as specified in “Procedure T—Criteria 

for and Verification of a Permanent or Temporary Total Enclosure” under 40 CFR 52.741, 

appendix B. 
(g) An owner or operator shall record, on a semiannual basis, the information specified in 

paragraphs (g)(1) and (g)(2) of this section for those planned routine maintenance operations that 

would require the control device not to meet the requirements of §63.693(d) through (h) of this 

subpart, as applicable. 

(1) A description of the planned routine maintenance that is anticipated to be performed for the 

control device during the next 6 months. This description shall include the type of maintenance 

necessary, planned frequency of maintenance, and lengths of maintenance periods. 

(2) A description of the planned routine maintenance that was performed for the control device 

during the previous 6 months. This description shall include the type of maintenance performed 

and the total number of hours during these 6 months that the control device did not meet the 

requirement of §63.693 (d) through (h) of this subpart, as applicable, due to planned routine 

maintenance. 

(h) An owner or operator shall record the malfunction information specified in paragraphs (h)(1) 

through (h)(3) of this section.

(1) In the event that an affected unit fails to meet an applicable standard, record the number of 

failures. For each failure, record the date, time and duration of the failure.

(2) For each failure to meet an applicable standard, record and retain a list of the affected sources 

or equipment, an estimate of the volume of each regulated pollutant emitted over any emission 

limit and a description of the method used to estimate the emissions. 

(3) Record actions taken to minimize emissions in accordance with § 63.683(e) of this subpart 

and any corrective actions taken to return the affected unit to its normal or usual manner of 

operation.

(i) For pressure relief devices in off-site material service, keep records of the information 

specified in paragraphs (i)(1) through (5) of this section, as applicable.

(1) A list of identification numbers for pressure relief devices that the owner or operator elects to

route emissions through a closed-vent system to a control device, process or drain system under 

the provisions in § 63.691(c)(4) of this subpart.

(2) A list of identification numbers for pressure relief devices that do not consist of or include a 

rupture disk, subject to the provisions in § 63.691(c)(2)(i) of this subpart.

(3) A list of identification numbers for pressure relief devices equipped with rupture disks, 

subject to the provisions in § 63.691(c)(2)(ii) of this subpart.

(4) The dates and results of the Method 21 of 40 CFR part 60, appendix A, monitoring following 

a pressure release for each pressure relief device subject to the provisions in § 63.691(c)(2)(i) of 

this subpart. The results of each monitoring event shall include:
(i) The measured background level.

(ii) The maximum instrument reading measured at each pressure relief device.

(5) For pressure relief devices in off-site material service subject to § 63.691(c)(3) of this 

subpart, keep records of each pressure release to the atmosphere, including the following 

information:

(i) The source, nature, and cause of the pressure release.

(ii) The date, time, and duration of the pressure release.

(iii) An estimate of the quantity of HAP listed in Table 1 of this subpart emitted during the 

pressure release and the calculations used for determining this quantity.

(iv) The actions taken to prevent this pressure release.

(v) The measures adopted to prevent future such pressure releases.

(j) (1) For pressure tank closure devices, as specified in § 63.685(h)(2) of this subpart, keep 

records of each release to the atmosphere, including the information specified in paragraphs

(j)(3) though (7) of this section.

(2) For each closed vent system that includes bypass devices that could divert a stream away

from the control device and into the atmosphere, as specified in § 63.693(c)(2) of this subpart, 

and each open-ended valve or line in an emergency shutdown system which is designed to open 

automatically in the event of a process upset, as specified in 40 CFR 63.167(d) or 40 CFR 

61.242-6(d), keep records of each release to the atmosphere, including the information specified 

in paragraphs (j)(3) though (9) of this section.

(3) The source, nature, and cause of the release.

(4) The date, time, and duration of the release.

(5) An estimate of the quantity of HAP listed in Table 1 of this subpart emitted during the release 

and the calculations used for determining this quantity.

(6) The actions taken to prevent this release.

(7) The measures adopted to prevent future such release.

(8) Hourly records of whether the bypass flow indicator specified under § 63.693(c)(2) of this 

subpart was operating and whether a diversion was detected at any time during the hour, as well 

as records of the times of all periods when the vent stream is diverted from the control device or 

the flow indicator is not operating.
(9) Where a seal mechanism is used to comply with § 63.693(c)(2) of this subpart, hourly records 

of flow are not required. In such cases, the owner or operator shall record that the monthly visual 

inspection of the seals or closure mechanism has been done, and shall record the duration of all 

periods when the seal mechanism is broken, the bypass line valve position has changed, or the 

key for a lock-and-key type lock has been checked out, and records of any car-seal that has 

broken.

§63.697 Reporting requirements.

(a) Each owner or operator of an affected source subject to this subpart must comply with the 

notification requirements specified in paragraph (a)(1) of this section and the reporting 

requirements specified in paragraph (a)(2) and (3) of this section.

(1) The owner or operator of an affected source must submit notices to the Administrator in 

accordance with the applicable notification requirements in 40 CFR 63.9 as specified in Table 2 

of this subpart. For the purpose of this subpart, an owner or operator subject to the initial 

notification requirements under 40 CFR 63.9(b)(2) must submit the required notification on or 

before October 19, 1999.

(i) For pressure relief devices in off-site material service subject to the requirements of §

63.691(c) of this subpart, the owner or operator must submit the information listed in paragraph 

(a)(1)(ii) of this section in the notification of compliance status required under § 63.9(h) of this 

part within 150 days after the first applicable compliance date for pressure relief device 

monitoring.

(ii) For pressure relief devices in off-site material service, a description of the device or 

monitoring system to be implemented, including the pressure relief devices and process 

parameters to be monitored (if applicable), a description of the alarms or other methods by which 

operators will be notified of a pressure release, and a description of how the owner or operator 

will determine the information to be recorded under § 63.696(i)(5)(ii) through (iii) of this subpart

(i.e., the duration of the pressure release and the methodology and calculations for determining 

the quantity of HAP listed in Table 1 of this subpart emitted during the pressure release).(2) The 

owner or operator of an affected source must submit reports to the Administrator in accordance 

with the applicable reporting requirements in 40 CFR 63.10 as specified in Table 2 of this 

subpart.

(3) Electronic reporting. Within 60 days after the date of completing each performance test (as 

defined in § 63.2 of this part) required by this subpart, the owner or operator must submit the 

results of the performance test according to the manner specified by either paragraph (a)(3)(i) or 

(ii) of this section.

(i) For data collected using test methods supported by the EPA’s Electronic Reporting Tool 

(ERT) as listed on the EPA’s ERT Web site (http://www.epa.gov/ttn/chief/ert/index.html), the 

owner or operator must submit the results of the performance test to the EPA via the Compliance 

and Emissions Data Reporting Interface (CEDRI) accessed through the EPA’s Central Data 

Exchange (CDX) (http://cdx.epa.gov/epa_home.asp). Performance test data must be submitted in 
a file format generated through the use of the EPA’s ERT. Owners or operators who claim that 

some of the performance test information being submitted is confidential business information 

(CBI) must submit a complete file generated through the use of the EPA’s ERT, including

information claimed to be CBI, on a compact disc, flash drive, or other commonly used 

electronic storage media to the EPA. The electronic media must be clearly marked as CBI and 

mailed to U.S. EPA/OAPQS/CORE CBI Office, Attention: Group Leader, Measurement Policy

Group, MD C404-02, 4930 Old Page Road, Durham, NC 27703. The same ERT file with the 

CBI omitted must be submitted to the EPA via the EPA’s CDX as described earlier in this 

paragraph (a)(3)(i).

(ii) For data collected using test methods that are not supported by the EPA’s ERT as listed on 

the EPA’s ERT Web site, the owner or operator must submit the results of the performance test 

to the Administrator at the appropriate address listed in 40 CFR 60.4.(b) The owner or operator 

of a control device used to meet the requirements of §63.693 of this subpart shall submit the 

following notifications and reports to the Administrator:

(1) A Notification of Performance Tests specified in §63.7 and §63.9(g) of this part,

(2) Performance test reports specified in §63.10(d)(2) of this part, and

(3) Reports of malfunctions. If a source fails to meet an applicable standard, report such events in 

the Periodic Report. Report the number of failures to meet an applicable standard. For each 

instance, report the date, time and duration of each failure. For each failure the report must 

include a list of the affected sources or equipment, an estimate of the volume of each regulated

pollutant emitted over any emission limit, and a description of the method used to estimate the 

emissions. 

(4) A summary report specified in § 63.10(e)(3) of this part shall be submitted on a semiannual 

basis (i.e., once every 6-month period). The summary report must include a description of all 

deviations as defined in § 63.683(f) and § 63.695(e) of this subpart that have occurred during the 

6-month reporting period. For each deviation caused when the daily average value of a 

monitored operating parameter is less than the minimum operating parameter limit (or, if 

applicable, greater than the maximum operating parameter limit), the report must include the 

daily average values of the monitored parameter, the applicable operating parameter limit, and 

the date and duration of the period that the deviation occurred. For each deviation caused by lack 

of monitoring data, the report must include the date and duration of period when the monitoring 

data were not collected and the reason why the data were not collected.

(5) For pressure relief devices in off-site material service subject to § 63.691(c) of this subpart, 

Periodic Reports must include the information specified in paragraphs (b)(5)(i) through (iii) of 

this section.

(i) For pressure relief devices in off-site material service subject to § 63.691(c) of this subpart, 

report the results of all monitoring conducted within the reporting period.
(ii) For pressure relief devices in off-site material service subject to § 63.691(c)(2)(i) of this 

subpart, report any instrument reading of 500 ppm above background or greater, if detected more 

than 5 days after the pressure release.

(iii) For pressure relief devices in off-site material service subject to § 63.691(c)(3) of this 

subpart, report each pressure release to the atmosphere, including the following information:

(A) The source, nature, and cause of the pressure release.

(B) The date, time, and duration of the pressure release.

(C) An estimate of the quantity of HAP listed in Table 1 of this subpart emitted during the 

pressure release and the method used for determining this quantity.

(D) The actions taken to prevent this pressure release.

(E) The measures adopted to prevent future such pressure releases.

(6) Pressure tank closure device or bypass deviation report. The owner or operator must submit 

to the Administrator the information specified in paragraph (b)(6)(iv) of this section when any of 

the conditions in paragraphs (b)(6)(i) through (iii) of this section are met. 

(i) Any pressure tank closure device, as specified in § 63.685(h)(2) of this subpart, has released 

to the atmosphere.

(ii) Any closed vent system that includes bypass devices that could divert a vent a stream away

from the control device and into the atmosphere, as specified in § 63.693(c)(2) of this subpart, 

has released directly to the atmosphere.

(iii) Any open-ended valve or line in an emergency shutdown system which is designed to open 

automatically in the event of a process upset, as specified in 40 CFR 63.167(d) or 40 CFR 

61.242-6(d), has released directly to the atmosphere.

(iv) The pressure tank closure device or bypass deviation report must include the information 

specified in paragraphs (b)(6)(iii)(A) through (E) of this section.

(A) The source, nature and cause of the release.

(B) The date, time and duration of the discharge.

(C) An estimate of the quantity of HAP listed in Table 1 of this subpart emitted during the 

release and the method used for determining this quantity.

(D) The actions taken to prevent this release.

(E) The measures adopted to prevent future such releases.
(c) Each owner or operator using an internal floating roof or external floating roof to comply

with the Tank Level 2 control requirements specified in §63.685(d) of this subpart shall notify

the Administrator in advance of each inspection required under §63.695(b) of this subpart to 

provide the Administrator with the opportunity to have an observer present during the inspection. 

The owner or operator shall notify the Administrator of the date and location of the inspection as 

follows: 

(1) Prior to each inspection to measure external floating roof seal gaps as required under 

§63.695(b) of this subpart, written notification shall be prepared and sent by the owner or 

operator so that it is received by the Administrator at least 30 calendar days before the date the 

measurements are scheduled to be performed. 

(2) Prior to each visual inspection of an internal floating roof or external floating roof in a tank 

that has been emptied and degassed, written notification shall be prepared and sent by the owner 

or operator so that it is received by the Administrator at least 30 calendar days before refilling 

the tank except when an inspection is not planned as provided for in paragraph (c)(3) of this 

section. 

(3) When a visual inspection is not planned and the owner or operator could not have known 

about the inspection 30 calendar days before refilling the tank, the owner or operator shall notify

the Administrator as soon as possible, but no later than 7 calendar days before refilling of the 

tank. This notification may be made by telephone and immediately followed by a written 

explanation for why the inspection is unplanned. Alternatively, written notification, including the 

explanation for the unplanned inspection, may be sent so that it is received by the Administrator 

at least 7 calendar days before refilling the tank. 

§63.698 Implementation and enforcement.

(a) This subpart can be implemented and enforced by the U.S. EPA, or a delegated authority

such as the applicable State, local, or Tribal agency. If the U.S. EPA Administrator has delegated 

authority to a State, local, or Tribal agency, then that agency, in addition to the U.S. EPA, has the 

authority to implement and enforce this subpart. Contact the applicable U.S. EPA Regional 

Office to find out if this subpart is delegated to a 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 cannot be transferred to the State, 

local, or Tribal agency.

(c) The authorities that cannot be delegated to State, local, or Tribal agencies are as specified in 

paragraphs (c)(1) through (5) of this section.

(1) Approval of alternatives to the requirements in §§63.680, 63.683 through 63.691, and 63.693. 

Where these standards reference another subpart, the cited provisions will be delegated 

according to the delegation provisions of the referenced subpart.
(2) Approval of major alternatives to test methods under §63.7(e)(2)(ii) and (f), as defined in 

§63.90, and as required in this subpart.

(3) Approval of major alternatives to monitoring under §63.8(f), as defined in §63.90, and as 

required in this subpart.

(4) Approval of major alternatives to recordkeeping and reporting under §63.10(f), as defined in 

§63.90, and as required in this subpart.

(5) Approval of alternatives to the electronic reporting requirements in § 63.697(a)(3).

Table 1 to Subpart DD of Part 63—List of Hazardous Air 

Pollutants (HAP) for Subpart DD 

CAS 

No.a Chemical name fm 305

75-07-0 Acetaldehyde 1.000

75-05-8 Acetonitrile 0.989

98-86-2 Acetophenone 0.314

107-02-

8

Acrolein 1.000

107-13-

1

Acrylonitrile 0.999

107-05-

1

Allyl chloride 1.000

71-43-2 Benzene (includes benzene in gasoline) 1.000

98-07-7 Benzotrichloride (isomers and mixture) 0.958

100-44-

7

Benzyl chloride 1.000

92-52-4 Biphenyl 0.864

542-88-

1

Bis(chloromethyl)etherb0.999

75-25-2 Bromoform 0.998

106-99-

0

1,3-Butadiene 1.000

75-15-0 Carbon disulfide 1.000

56-23-5 Carbon tetrachloride 1.000

43-58-1 Carbonyl sulfide 1.000

133-90-

4

Chloramben 0.633

108-90- Chlorobenzene 1.000
7

67-66-3 Chloroform 1.000

107-30-

2

Chloromethyl methyl etherb1.000

126-99-

8

Chloroprene 1.000

98-82-8 Cumene 1.000

94-75-7 2,4-D, salts and esters 0.167

334-88-

3

Diazomethane

c

0.999

132-64-

9

Dibenzofurans 0.967

96-12-8 1,2-Dibromo-3-chloropropane 1.000

106-46-

7

1,4-Dichlorobenzene(p) 1.000

107-06-

2

Dichloroethane (Ethylene dichloride) 1.000

111-44-

4

Dichloroethyl ether (Bis(2-chloroethyl ether) 0.757

542-75-

6

1,3-Dichloropropene 1.000

79-44-7 Dimethyl carbamoyl chloride

c

0.150

64-67-5 Diethyl sulfate 0.0025

77-78-1 Dimethyl sulfate 0.086

121-69-

7

N,N-Dimethylaniline 0.0008

51-28-5 2,4-Dinitrophenol 0.0077

121-14-

2

2,4-Dinitrotoluene 0.0848

123-91-

1

1,4-Dioxane (1,4-Diethyleneoxide) 0.869

106-89-

8

Epichlorohydrin (1-Chloro-2,3-epoxypropane) 0.939

106-88-

7

1,2-Epoxybutane 1.000

140-88-

5

Ethyl acrylate 1.000

100-41-

4

Ethyl benzene 1.000

75-00-3 Ethyl chloride (Chloroethane) 1.000
106-93-

4

Ethylene dibromide (Dibromoethane) 0.999

107-06-

2

Ethylene dichloride (1,2-Dichloroethane) 1.000

151-56-

4

Ethylene imine (Aziridine) 0.867

75-21-8 Ethylene oxide 1.000

75-34-3 Ethylidene dichloride (1,1-Dichloroethane) 1.000

Glycol ethersdthat have a Henry's Law constant value equal to or greater than 

0.1 Y/X (1.8×10−6 atm/gm-mole/m3) at 25°C

(e)

118-74-

1

Hexachlorobenzene 0.97

87-68-3 Hexachlorobutadiene 0.88

67-72-1 Hexachloroethane 0.499

110-54-

3

Hexane 1.000

78-59-1 Isophorone 0.506

58-89-9 Lindane (all isomers) 1.000

67-56-1 Methanol 0.855

74-83-9 Methyl bromide (Bromomethane) 1.000

74-87-3 Methyl chloride (Choromethane) 1.000

71-55-6 Methyl chloroform (1,1,1-Trichloroethane) 1.000

78-93-3 Methyl ethyl ketone (2-Butanone) 0.990

74-88-4 Methyl iodide (Iodomethane) 1.0001

108-10-

1

Methyl isobutyl ketone (Hexone) 0.9796

624-83-

9

Methyl isocyanate 1.000

80-62-6 Methyl methacrylate 0.916

1634-

04-4

Methyl tert butyl ether 1.000

75-09-2 Methylene chloride (Dichloromethane) 1.000

91-20-3 Naphthalene 0.994

98-95-3 Nitrobenzene 0.394

79-46-9 2-Nitropropane 0.989

82-68-8 Pentachloronitrobenzene (Quintobenzene) 0.839

87-86-5 Pentachlorophenol 0.0898

75-44-5 Phosgenec1.000

123-38- Propionaldehyde 0.999
6

78-87-5 Propylene dichloride (1,2-Dichloropropane) 1.000

75-56-9 Propylene oxide 1.000

75-55-8 1,2-Propylenimine (2-Methyl aziridine) 0.945

100-42-

5

Styrene 1.000

96-09-3 Styrene oxide 0.830

79-34-5 1,1,2,2-Tetrachloroethane 0.999

127-18-

4

Tetrachloroethylene (Perchloroethylene) 1.000

108-88-

3

Toluene 1.000

95-53-4o-Toluidine 0.152

120-82-

1

1,2,4-Trichlorobenzene 1.000

71-55-6 1,1,1-Trichloroethane (Methyl chlorform) 1.000

79-00-5 1,1,2-Trichloroethane (Vinyl trichloride) 1.000

79-01-6 Trichloroethylene 1.000

95-95-4 2,4,5-Trichlorophenol 0.108

88-06-2 2,4,6-Trichlorophenol 0.132

121-44-

8

Triethylamine 1.000

540-84-

1

2,2,4-Trimethylpentane 1.000

108-05-

4

Vinyl acetate 1.000

593-60-

2

Vinyl bromide 1.000

75-01-4 Vinyl chloride 1.000

75-35-4 Vinylidene chloride (1,1-Dichloroethylene) 1.000

1330-

20-7

Xylenes (isomers and mixture) 1.000

95-47-6o-Xylenes 1.000

108-38-

3

m-Xylenes 1.000

106-42-

3

p-Xylenes 1.000

Notes:
fm 305 = Method 305 fraction measure factor.

a. CAS numbers refer to the Chemical Abstracts Services registry number assigned to specific 

compounds, isomers, or mixtures of compounds.

b. Denotes a HAP that hydrolyzes quickly in water, but the hydrolysis products are also HAP 

chemicals.

c. Denotes a HAP that may react violently with water, exercise caustic is an expected analyte.

d. Denotes a HAP that hydrolyzes slowly in water.

e. The fm 305 factors for some of the more common glycol ethers can be obtained by contacting 

the Waste and Chemical Processes Group, Office of Air Quality Planning and Standards, 

Research Triangle Park, NC 27711.

Table 2 to Subpart DD of Part 63—Applicability of 

Paragraphs in Subpart A of This Part 63—General 

Provisions to Subpart DD 

Subpart A 

reference

Applies to 

Subpart 

DD

Explanation

63.1(a)(1) Yes

63.1(a)(2) Yes

63.1(a)(3) Yes

63.1(a)(4) No Subpart DD (this table) specifies applicability of each 

paragraph in subpart A to subpart DD.

63.1(a)(5)-

63.1(a)(9) No

63.1(a)(10) Yes

63.1(a)(11) Yes

63.1(a)(12) Yes

63.1(b)(1) No Subpart DD specifies its own applicability.

63.1(b)(2) No Reserved

63.1(b)(3) No

63.1(c)(1) No Subpart DD explicitly specifies requirements that apply.

63.1(c)(2) No Area sources are not subject to subpart DD.

63.1(c)(3) No Reserved

63.1(c)(4) No Reserved

63.1(c)(5) Yes Except that sources are not required to submit notifications 
overridden by this table.

63.1(d) No

63.1(e) No

63.2 Yes

§63.681 of subpart DD specifies that if the same term is defined 

in subparts A and DD, it shall have the meaning given in 

subpart DD.

63.3 Yes

63.4(a)(1)-(2) Yes

63.4(a)(3) No Reserved

63.4(a)(4) No Reserved.

63.4(a)(5) No Reserved

63.4(b) Yes

63.4(c) Yes

63.5(a)(1) Yes

63.5(a)(2) Yes

63.5(b)(1) Yes

63.5(b)(2) No Reserved.

63.5(b)(3) Yes

63.5(b)(4) Yes Except the cross-reference to §63.9(b) is changed to §63.9(b)(4) 

and (5). Subpart DD overrides §63.9(b)(2) and (b)(3).

63.5(b)(5) No Reserved

63.5(b)(6) Yes

63.5(c) No Reserved.

63.5(d)(1)(i) Yes

63.5(d)(1)(ii) Yes

63.5(d)(1)(iii) Yes

63.5(d)(2) No

63.5(d)(3) Yes

63.5(d)(4) Yes

63.5(e) Yes

63.5(f)(1) Yes

63.5(f)(2) Yes

63.6(a) Yes

63.6(b)(1) No Subpart DD specifies compliance dates for sources subject to 

subpart DD.

63.6(b)(2) No

63.6(b)(3) No

63.6(b)(4) No
63.6(b)(5) No §63.697 of subpart DD includes notification requirements.

63.6(b)(6) No

63.6(b)(7) No

63.6(c)(1) No §63.680 of subpart DD specifies the compliance date.

63.6(c)(2)-

63.6(c)(4) No

63.6(c)(5) Yes

63.6(d) No

63.6(e)(1)(i) No See § 63.683(e) of this subpart for general duty requirement.

63.6(e)(1)(ii) No

63.6(e)(1)(iii) Yes

63.6(e)(2) No Reserved.

63.6(e)(3) No

63.6(f)(1) No

63.6(f)(2)(i) Yes

63.6(f)(2)(ii) Yes Subpart DD specifies the use of monitoring data in determining 

compliance with subpart DD.

63.6(f)(2)(iii) (A), 

(B), and (C) Yes

63.6(f)(2)(iii) (D) No

63.6(f)(2)(iv) Yes

63.6(f)(2)(v) Yes

63.6(f)(3) Yes

63.6(g) Yes

63.6(h) No Subpart DD does not require opacity and visible emission 

standards.

63.6(i) Yes Except for §63.6(i)(15), which is reserved.

63.6(j) Yes

63.7(a)(1) No Subpart DD specifies required testing and compliance 

demonstration procedures.

63.7(a)(2) Yes

63.7(a)(3) Yes

63.7(a)(4) Yes

63.7(b) Yes

63.7(c) Yes

63.7(d) Yes

63.7(e)(1) No See § 63.694(l) of this subpart. 

63.7(e)(2) Yes
63.7(e)(3) No Subpart DD specifies test methods and procedures.

63.7(e)(4) Yes

63.7(f) Yes

63.7(g) Yes

63.7(h)(1) Yes

63.7(h)(2) Yes

63.7(h)(3) Yes

63.7(h)(4) No

63.7(h)(5) Yes

63.8(a) No

63.8(b)(1) Yes

63.8(b)(2) No Subpart DD specifies locations to conduct monitoring.

63.8(b)(3) Yes

63.8(c)(1)(i) Yes

63.8(c)(1)(ii) Yes

63.8(c)(1)(iii) No

63.8(c)(2) Yes

63.8(c)(3) Yes

63.8(c)(4) No Subpart DD specifies monitoring frequency

63.8(c)(5)-

63.8(c)(8) No

63.8(d) No

63.8(e) No

63.8(f)(1) Yes

63.8(f)(2) Yes

63.8(f)(3) Yes

63.8(f)(4)(i) Yes

63.8(f)(4)(ii) Yes

63.8(f)(4)(iii) No

63.8(f)(5)(i) Yes

63.8(f)(5)(ii) No

63.8(f)(5)(iii) Yes

63.8(f)(6) Yes

63.8(g) Yes

63.9(a) Yes

63.9(b)(1)(i) Yes

63.9(b)(1)(ii) No

63.9(b)(2) Yes
63.9(b)(3) No

63.9(b)(4) Yes

63.9(b)(5) Yes

63.9(c) Yes

63.9(d) Yes

63.9(e) Yes

63.9(f) No

63.9(g) Yes

63.9(h) Yes

63.9(i) Yes

63.9(j) No

63.10(a) Yes

63.10(b)(1) Yes

63.10(b)(2)(i) No

63.10(b)(2)(ii) No

See § 63.696(h) of this subpart for recordkeeping of (1) date, 

time and duration; (2) listing of affected source or equipment, 

and an estimate of the volume of each regulated pollutant 

emitted over the standard; and (3) actions to minimize 

emissions and correct the failure.

63.10(b)(2)(iii) Yes

63.10(b)(2)(iv) No

63.10(b)(2)(v) No

63.10(b)(2)(vi)-(ix) Yes

63.10(b)(2)(x)-(xi) Yes

63.10(b)(2) (xii)-

(xiv) No

63.10(b)(3) Yes

63.10(c)(1)-(6) No

63.10(c)(7)-(8) Yes

63.10(c)(9)-(15) No

63.10(d)(1) No

63.10(d)(2) Yes

63.10(d)(3) No

63.10(d)(4) Yes

63.10(d)(5) No See § 63.697(b)(3) of this subpart for reporting of malfunctions.

63.10(e)(1)- (2) No

63.10(e)(3) Yes

63.10(e)(4) No
63.10(f) Yes

63.11-63.15 Yes 

63.16 No

aWherever subpart A specifies “postmark” dates, submittals may be sent by methods other than 

the U.S. Mail (e.g., by fax or courier). Submittals shall be sent by the specified dates, but a 

postmark is not required.

Table 3 to Subpart DD of Part 63—Tank Control Levels for 

Tanks at Existing Affected Sources as Required by 40 CFR 

63.685(b)(1)(i)

Tank design 

capacity (cubic 

meters)

Maximum HAP vapor 

pressure of off-site 

material managed in 

tank (kilopascals) 

Tank control level 

Design capacity

less than 75 m3

Maximum HAP vapor 

pressure less than 76.6 kPa Level 1. 

Design capacity

less than 75 m3

Maximum HAP vapor 

pressure equal to or greater 

than 76.6 kPa

Level 2, except that fixed roof tanks equipped 

with an internal floating roof and tanks 

equipped with an external floating roof as 

provided for in § 63.685(d)(1) and (2) of this 

subpart shall not be used.

Design capacity

equal to or greater 

than 75 m3and less 

than 151 m3

Maximum HAP vapor 

pressure less than 27.6 kPa Level 1. 

Maximum HAP vapor 

pressure equal to or greater 

than 27.6 kPa

Level 2. 

Design capacity

equal to or greater 

than 151 m3

Maximum HAP vapor 

pressure less than 5.2 kPa Level 1. 

Maximum HAP vapor 

pressure equal to or greater 

than 5.2 kPa

Level 2.

Table 4 to Subpart DD of Part 63—Tank Control Levels for 

Tanks at Existing Affected Sources as Required by 40 CFR 

63.685(b)(1)(ii)
Tank design 

capacity (cubic 

meters)

Maximum HAP vapor 

pressure of off-site 

material managed in 

tank (kilopascals) 

Tank control level 

Design capacity

less than 75 m3

Maximum HAP vapor 

pressure less than 76.6 kPa Level 1. 

Design capacity

less than 75 m3

Maximum HAP vapor 

pressure equal to or greater 

than 76.6 kPa

Level 2, except that fixed roof tanks equipped 

with an internal floating roof and tanks 

equipped with an external floating roof as 

provided for in § 63.685(d)(1) and (2) of this 

subpart shall not be used.

Design capacity

equal to or greater 

than 75 m3and less 

than 151 m3

Maximum HAP vapor 

pressure less than 13.1 kPa Level 1. 

Maximum HAP vapor 

pressure equal to or greater 

than 13.1 kPa

Level 2. 

Design capacity

equal to or greater 

than 151 m3

Maximum HAP vapor 

pressure less than 5.2 kPa Level 1. 

Maximum HAP vapor 

pressure equal to or greater 

than 5.2 kPa

Level 2.

Table 5 to Subpart DD of Part 63—Tank Control Levels for 

Tanks at New Affected Sources as Required by 40 CFR 

63.685(b)(2)

Tank design 

capacity (cubic 

meters)

Maximum HAP vapor 

pressure of off-site 

material managed in 

tank (kilopascals) 

Tank control level 

Design capacity

less than 38 m3

Maximum HAP vapor 

pressure less than 76.6 kPa Level 1. 

Design capacity

less than 38 m3

Maximum HAP vapor 

pressure equal to or greater 

than 76.6 kPa

Level 2, except that fixed roof tanks equipped 

with an internal floating roof and tanks 

equipped with an external floating roof as 

provided for in § 63.685(d)(1) and (2) of this 

subpart shall not be used.
Design capacity

equal to or greater 

than 38 m3and less 

than 151 m3

Maximum HAP vapor 

pressure less than 13.1 kPa Level 1.

Maximum HAP vapor 

pressure equal to or greater 

than 13.1 kPa

Level 2.

Design capacity

equal to or greater 

than 151 m3

Maximum HAP vapor 

pressure less than 0.7 kPa Level 1.

Maximum HAP vapor 

pressure equal to or greater 

than 0.7 kPa

Level 2.