§63.484. Storage vessel provisions. — Inbound Citations

(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. However, if a period of non-operation of one portion of an affected source does not affect the ability of a particular emission point to comply with the emission limitations to which it is subject, then that emission point shall still be required to comply with the applicable emission limitations of this subpart during the period of non-operation. For example, if there is an overpressure in the reactor area, a storage vessel that is part of the affected source would still be required to be controlled in accordance with the emission limitations in § 63.484.

(b) All other terms used in this subpart shall have the meaning given them in this section. If a term is defined in a subpart referenced in this section, it shall have the meaning given in this section for purposes of this subpart.

Affected source is defined in § 63.480(a).

Affirmative defense means, in the context of an enforcement proceeding, a response or a defense put forward by a defendant, regarding which the defendant has the burden of proof, and the merits of which are independently and objectively evaluated in a judicial or administrative proceeding. Beginning on July 15, 2024, this definition of affirmative defense no longer applies.

Aggregate batch vent stream means a gaseous emission stream containing only the exhausts from two or more batch front-end process vents that are ducted, hard-piped, or otherwise connected together for a continuous flow.

Annual average batch vent concentration is determined using Equation 17, as described in § 63.488(h)(2) for halogenated compounds.

Annual average batch vent flow rate is determined by the procedures in § 63.488(e)(3).

Annual average concentration, as used in the wastewater provisions, means the flow-weighted annual average concentration, as determined according to the procedures specified in § 63.144(b), with the exceptions noted in § 63.501, for the purposes of this subpart.

Annual average flow rate, as used in the wastewater provisions, means the annual average flow rate, as determined according to the procedures specified in § 63.144(c), with the exceptions noted in § 63.501, for the purposes of this subpart.

Average batch vent concentration is determined by the procedures in § 63.488(b)(5)(iii) for HAP concentrations and is determined by the procedures in § 63.488(h)(1)(iii) for organic compounds containing halogens and hydrogen halides.

Average batch vent flow rate is determined by the procedures in § 63.488(e)(1) and (2).

Back-end refers to the unit operations in an EPPU following the stripping operations. Back-end process operations include, but are not limited to, filtering, coagulation, blending, concentration, drying, separating, and other finishing operations, as well as latex and crumb storage. Back-end does not include storage and loading of finished product or emission points that are regulated under § 63.484, § 63.501, or § 63.502.

Batch cycle means the operational step or steps, from start to finish, that occur as part of a batch unit operation.

Batch emission episode means a discrete emission venting episode associated with a single batch unit operation. Multiple batch emission episodes may occur from a single batch unit operation.

Batch front-end process vent means a process vent with annual organic HAP emissions greater than 225 kilograms per year from a batch unit operation within an affected source and located in the front-end of a process unit. Annual organic HAP emissions are determined as specified in § 63.488(b) at the location specified in § 63.488(a)(2).

Batch mass input limitation means an enforceable restriction on the total mass of HAP or material that can be input to a batch unit operation in one year.

Batch mode means the discontinuous bulk movement of material through a unit operation. Mass, temperature, concentration, and other properties may vary with time. For a unit operation operated in a batch mode (i.e., batch unit operation), the addition of material and withdrawal of material do not typically occur simultaneously.

Batch process means, for the purposes of this subpart, a process where the reactor(s) is operated in a batch mode.

Batch unit operation means a unit operation operated in a batch mode.

Block polymer means a polymer where the polymerization is controlled, usually by performing discrete polymerization steps, such that the final polymer is arranged in a distinct pattern of repeating units of the same monomer.

Butyl rubber means a copolymer of isobutylene and other monomers. Typical other monomers include isoprene and methylstyrene. A typical composition of butyl rubber is approximately 85- to 99-percent isobutylene, and 1- to 15-percent other monomers. Most butyl rubber is produced by precipitation polymerization, although other methods may be used. Halobutyl rubber is a type of butyl rubber elastomer produced using halogenated copolymers.

Combined vent stream, as used in reference to batch front-end process vents, continuous front-end process vents, and aggregate batch vent streams, means the emissions from a combination of two or more of the aforementioned types of process vents. The primary occurrence of a combined vent stream is as combined emissions from a continuous front-end process vent and a batch front-end process vent.

Combustion device burner means a device designed to mix and ignite fuel and air to provide a flame to heat and oxidize waste organic vapors in a combustion device.

Compounding unit means a unit operation which blends, melts, and resolidifies solid polymers for the purpose of incorporating additives, colorants, or stabilizers into the final elastomer product. A unit operation whose primary purpose is to remove residual monomers from polymers is not a compounding unit.

Construction means the on-site fabrication, erection, or installation of an affected source. Construction also means the on-site fabrication, erection, or installation of a process unit or combination of process units which subsequently becomes an affected source or part of an affected source, due to a change in primary product.

Continuous front-end process vent means a process vent located in the front-end of a process unit and containing greater than 0.005 weight percent total organic HAP from a continuous unit operation within an affected source. The total organic HAP weight percent is determined after the last recovery device, as described in § 63.115(a), and is determined as specified in § 63.115(c).

Continuous mode means the continuous movement of material through a unit operation. Mass, temperature, concentration, and other properties typically approach steady-state conditions. For a unit operation operated in a continuous mode (i.e., continuous unit operation), the simultaneous addition of raw material and withdrawal of product is typical.

Continuous process means, for the purposes of this subpart, a process where the reactor(s) is operated in a continuous mode.

Continuous record means documentation, either in hard copy or computer readable form, of data values measured at least once every 15 minutes and recorded at the frequency specified in § 63.506(d) or (h).

Continuous recorder means a data recording device that either records an instantaneous data value at least once every 15 minutes or records 1—hour or more frequent block average values.

Continuous unit operation means a unit operation operated in a continuous mode.

Control device is defined in § 63.111, except that the term “continuous front-end process vent” shall apply instead of the term “process vent,” for the purpose of this subpart.

Crumb rubber dry weight means the weight of the polymer, minus the weight of water and residual organics.

Dioxins and furans means total tetra- through octachlorinated dibenzo-p-dioxins and dibenzofurans.

Drawing unit means a unit operation which converts polymer into a different shape by melting or mixing the polymer and then pulling it through an orifice to create a continuously extruded product.

Elastomer means any polymer having a glass transition temperature lower than −10 °C, or a glass transition temperature between −10 °C and 25 °C that is capable of undergoing deformation (stretching) of several hundred percent and recovering essentially when the stress is removed. For the purposes of this subpart, resins are not considered to be elastomers.

Elastomer product means one of the following types of products, as they are defined in this section:

(1) Section 63.484 for storage vessels;

(2) When the storage vessel requirements contained in §§ 63.119 through 63.123 are referred to in §§ 63.132 through 63.149, §§ 63.119 through 63.123 are applicable, with the exception of the differences referred to in § 63.484, for the purposes of this subpart.

(a) The owner or operator of each affected source, shall comply with the requirements of subpart H of this part, with the exceptions noted in paragraphs (a)(1) through (7), and (b) through (m) of this section. Except as specified in § 63.170(b), surge control vessels required to be controlled by subpart H may, alternatively, comply with the Group 1 storage vessel provisions specified in § 63.484.

(1) Substitute “For each affected source as described in § 63.480, on and after July 15, 2027,” for each occurrence of “For each source as defined in § 63.101, and for each source as defined in § 63.191, on and after July 15, 2027,”.

(2) Substitute “For each affected source as described in § 63.480, beginning no later than the compliance dates specified in § 63.481(n),” for each occurrence of “For each source as defined in § 63.101, and for each source as defined in § 63.191, beginning no later than the compliance dates specified in § 63.100(k)(10),”.

(3) Substitute “For each affected source as described in § 63.480, beginning no later than the compliance dates specified in § 63.481(o),” for each occurrence of “For each source as defined in § 63.101, and for each source as defined in § 63.191, beginning no later than the compliance dates specified in § 63.100(k)(11),”.

(4) Substitute “For each affected source as described in § 63.480, beginning no later than the compliance dates specified in § 63.481(p),” for each occurrence of “For each source as defined in § 63.101, and for each source as defined in § 63.191, beginning no later than the compliance dates specified in § 63.100(k)(12),”.

(5) Substitute “§ 63.508” for each occurrence of “§ 63.108”.

(7) If an affected source uses, produces, stores, or emits chloroprene, the action level for chloroprene in § 63.184(d)(3) is 0.3 µg/m 3 on an annual average basis for the purposes of this subpart. Additionally, the sampling period Δc in § 63.184(e)(4)(iii) and (f)(1)(iii) is 0.3 µg/m 3 instead of 0.8 µg/m 3 for the purposes of this subpart.

(a) This section applies to owners or operators of existing affected sources who seek to comply with § 63.483(b) by using emissions averaging rather than following the provisions of §§ 63.484, 63.485, 63.486, 63.494, and 63.501.

(i) All emission points included in an emissions average shall be from the same affected source. There may be an emissions average for each individual affected source located at a plant site.

(A) If a plant site has only one affected source for which emissions averaging is being used to demonstrate compliance, the number of emission points allowed to be included in the emission average is limited to twenty. This number may be increased by up to five additional points if pollution prevention measures are used to control five or more of the emission points included in the emissions average.

(B) If a plant site has two or more affected sources for which emissions averaging is being used to demonstrate compliance, the number of emission points allowed in the emissions average for those affected sources is limited to twenty. This number may be increased by up to five additional emission points if pollution prevention measures are used to control five or more of the emission points included in the emissions averages.

(2) Compliance with the provisions of this section may be based on either organic HAP or TOC.

(3) For the purposes of the provisions in this section, whenever Method 18 of appendix A-6 to 40 CFR part 60 is specified within the paragraphs of this section or is specified by reference through provisions outside this section, Method 18 or Method 25A of appendices A-6 and A-7 to 40 CFR part 60, respectively, may be used. ASTM D6420-18 (incorporated by reference, see § 63.14) may also be used in lieu of Method 18, if the target compounds are all known and are all listed in Section 1.1 of ASTM D6420-18 as measurable; ASTM D6420-18 must not be used for methane and ethane; and ASTM D6420-18 may not be used as a total VOC method. The use of Method 25A, must conform with the requirements in paragraphs (a)(3)(i) and (ii) of this section.

(i) The organic HAP used as the calibration gas for Method 25Aof appendix A-7 to 40 CFR part 60 must be the single organic HAP representing the largest percent by volume of the emissions.

(ii) The use of Method 25A of appendix A-7 to 40 CFR part 60, is acceptable if the response from the high-level calibration gas is at least 20 times the standard deviation of the response from the zero calibration gas when the instrument is zeroed on the most sensitive scale.

(a) Performance testing shall be conducted in accordance with § 63.7(a)(1), (a)(3), (d), (e)(1) and (2), (e)(4), (g), and (h), with the exceptions specified in paragraphs (a)(1) through (5) of this section and the additions specified in paragraph (b) of this section. Sections 63.484 through 63.501 also contain specific testing requirements. Beginning no later than the compliance dates specified in § 63.481(n), conduct subsequent performance tests no later than 60 calendar months after the previous performance test.

(1) Except as specified in paragraph (a)(1)(iii) of this section, performance tests shall be conducted at maximum representative operating conditions achievable during one of the time periods described in paragraph (a)(1)(i) of this section, without causing any of the situations described in paragraph (a)(1)(ii) of this section to occur. 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.

(i) The 6-month period that ends 2 months before the Notification of Compliance Status is due, according to § 63.506(e)(5); or the 6-month period that begins 3 months before the performance test and ends 3 months after the performance test.

(ii) Causing damage to equipment; necessitating that the owner or operator make product that does not meet an existing specification for sale to a customer; or necessitating that the owner or operator make product in excess of demand.

(iii) Beginning no later than the compliance dates specified in § 63.481(n), paragraphs (a)(1)(i) and (ii) of this section no longer applies and instead the owner or operator must conduct performance tests under such conditions as the Administrator specifies based on representative performance of the affected source for the period being tested. Representative conditions exclude periods of startup and shutdown. You may not conduct performance tests during periods of malfunction. You 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, you must make available to the Administrator such records as may be necessary to determine the conditions of performance tests.

(2) References in § 63.7(g) to the Notification of Compliance Status requirements in § 63.9(h) shall refer to the requirements in § 63.506(e)(5).

(3) Because the site-specific test plans in § 63.7(c)(3) are not required, § 63.7(h)(4)(ii) is not applicable.

(4) The owner or operator shall notify the Administrator of the intent to conduct a performance test at least 30 days before the performance test is scheduled, to allow the Administrator the opportunity to have an observer present during the test. If after 30 days notice for an initially scheduled performance test, there is a delay (due to operational problems, etc.) in conducting the scheduled performance test, the owner or operator of an affected facility shall notify the Administrator as soon as possible of any delay in the original test date, either by providing at least 7 days prior notice of the rescheduled date of the performance test, or by arranging a rescheduled date with the Administrator by mutual agreement.

(5) Performance tests shall be performed no later than 150 days after the compliance dates specified in this subpart (i.e., in time for the results to be included in the Notification of Compliance Status), rather than according to the time periods in § 63.7(a)(2).

(i) The results of any emission point group determinations, process section applicability determinations, performance tests, inspections, any other information used to demonstrate compliance, values of monitored parameters established during performance tests, and any other information required to be included in the Notification of Compliance Status under §§ 63.122 and 63.484 for storage vessels, § 63.117 for continuous front-end process vents, § 63.492 for batch front-end process vents, § 63.499 for back-end process operations, § 63.146 for process wastewater, and § 63.503 for emission points included in an emissions average. In addition, the owner or operator of an affected source shall comply with paragraphs (e)(5)(i)(A) and (B) of this section.

(A) For performance tests, group determinations, and process section applicability determinations that are based on measurements, the Notification of Compliance Status shall include one complete test report, except as specified in paragraph (e)(5)(i)(B) of this section, for each test method used for a particular kind of emission point. For additional tests performed for the same kind of emission point using the same method, the results and any other information, from the test report, that is requested on a case-by-case basis by the Administrator shall be submitted, but a complete test report is not required.

(B) If the performance test results have been submitted electronically via the Compliance and Emissions Data Reporting Interface (CEDRI) in accordance with paragraph (i) of this section, the unit(s) tested, the pollutant(s) tested, and the date that such performance test was conducted may be submitted in the Notification of Compliance Status in lieu of the performance test report. The performance test results must be submitted to CEDRI by the date the Notification of Compliance Status is submitted. A complete test report shall include a brief process description, sampling site description, description of sampling and analysis procedures and any modifications to standard procedures, quality assurance procedures, record of operating conditions during the test, record of preparation of standards, record of calibrations, raw data sheets for field sampling, raw data sheets for field and laboratory analyses, documentation of calculations, and any other information required by the test method.

(1) Approval of alternatives to the requirements in §§ 63.480 through 63.481, 63.483(a) through (c), 63.484, 63.485(a) through (k), (m) through (s), (u), 63.486 through 63.487, 63.488(a), (b)(1) through (4), (5)(iv) through (v), (6) through (7), (c) through (i), 63.493 through 63.494, 63.500(a)(1) through (3), (b), 63.501, 63.502(a) through (f), (i), (k) through (m), and 63.503. Where these standards reference another subpart, the cited provisions will be delegated according to the delegation provisions of the referenced subpart. Where these standards reference another subpart and modify the requirements, the requirements shall be modified as described in this subpart. Delegation of the modified requirements will also occur according to the delegation provisions of the referenced subpart.

(b) Storage vessels described in paragraphs (b)(1) through (b)(7) of this section are exempt from the storage vessel requirements of this section.

(1) Storage vessels containing styrene-butadiene latex;

(2) Storage vessels containing latex products other than styrene-butadiene latex, located downstream of the stripping operations;

(3) Storage vessels containing high conversion latex products;

(4) Storage vessels located downstream of the stripping operations at affected sources subject to the back-end residual organic HAP limitation located in § 63.494(a)(1) through (3), that are complying through the use of stripping technology, as specified in § 63.495;

(5) Storage vessels containing styrene;

(6) Storage vessels containing acrylamide; and

(b) Storage vessels described in paragraphs (b)(1) through (b)(7) of this section are exempt from the storage vessel requirements of this section.

(1) Storage vessels containing styrene-butadiene latex;

(2) Storage vessels containing latex products other than styrene-butadiene latex, located downstream of the stripping operations;

(3) Storage vessels containing high conversion latex products;

(4) Storage vessels located downstream of the stripping operations at affected sources subject to the back-end residual organic HAP limitation located in § 63.494(a)(1) through (3), that are complying through the use of stripping technology, as specified in § 63.495;

(5) Storage vessels containing styrene;

(6) Storage vessels containing acrylamide; and

(b) Storage vessels described in paragraphs (b)(1) through (b)(7) of this section are exempt from the storage vessel requirements of this section.

(1) Storage vessels containing styrene-butadiene latex;

(2) Storage vessels containing latex products other than styrene-butadiene latex, located downstream of the stripping operations;

(3) Storage vessels containing high conversion latex products;

(4) Storage vessels located downstream of the stripping operations at affected sources subject to the back-end residual organic HAP limitation located in § 63.494(a)(1) through (3), that are complying through the use of stripping technology, as specified in § 63.495;

(5) Storage vessels containing styrene;

(6) Storage vessels containing acrylamide; and

(b) Storage vessels described in paragraphs (b)(1) through (b)(7) of this section are exempt from the storage vessel requirements of this section.

(1) Storage vessels containing styrene-butadiene latex;

(2) Storage vessels containing latex products other than styrene-butadiene latex, located downstream of the stripping operations;

(3) Storage vessels containing high conversion latex products;

(4) Storage vessels located downstream of the stripping operations at affected sources subject to the back-end residual organic HAP limitation located in § 63.494(a)(1) through (3), that are complying through the use of stripping technology, as specified in § 63.495;

(5) Storage vessels containing styrene;

(6) Storage vessels containing acrylamide; and

(b) Storage vessels described in paragraphs (b)(1) through (b)(7) of this section are exempt from the storage vessel requirements of this section.

(1) Storage vessels containing styrene-butadiene latex;

(2) Storage vessels containing latex products other than styrene-butadiene latex, located downstream of the stripping operations;

(3) Storage vessels containing high conversion latex products;

(4) Storage vessels located downstream of the stripping operations at affected sources subject to the back-end residual organic HAP limitation located in § 63.494(a)(1) through (3), that are complying through the use of stripping technology, as specified in § 63.495;

(5) Storage vessels containing styrene;

(6) Storage vessels containing acrylamide; and

(b) Storage vessels described in paragraphs (b)(1) through (b)(7) of this section are exempt from the storage vessel requirements of this section.

(1) Storage vessels containing styrene-butadiene latex;

(2) Storage vessels containing latex products other than styrene-butadiene latex, located downstream of the stripping operations;

(3) Storage vessels containing high conversion latex products;

(4) Storage vessels located downstream of the stripping operations at affected sources subject to the back-end residual organic HAP limitation located in § 63.494(a)(1) through (3), that are complying through the use of stripping technology, as specified in § 63.495;

(5) Storage vessels containing styrene;

(6) Storage vessels containing acrylamide; and

(b) Storage vessels described in paragraphs (b)(1) through (b)(7) of this section are exempt from the storage vessel requirements of this section.

(1) Storage vessels containing styrene-butadiene latex;

(2) Storage vessels containing latex products other than styrene-butadiene latex, located downstream of the stripping operations;

(3) Storage vessels containing high conversion latex products;

(4) Storage vessels located downstream of the stripping operations at affected sources subject to the back-end residual organic HAP limitation located in § 63.494(a)(1) through (3), that are complying through the use of stripping technology, as specified in § 63.495;

(5) Storage vessels containing styrene;

(6) Storage vessels containing acrylamide; and

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(d) Owners or operators required to keep continuous records shall keep records as specified in paragraphs (d)(1) through (d)(7) of this section, unless an alternative recordkeeping system has been requested and approved as specified in paragraph (g) of this section, and except as provided in paragraph (h) of this section. If a monitoring plan for storage vessels pursuant to § 63.484(k) requires continuous records, the monitoring plan shall specify which provisions, if any, of paragraphs (d)(1) through (d)(7) of this section apply. As described in § 63.484(k), certain storage vessels are not required to keep continuous records as specified in this paragraph. Owners and operators of such storage vessels shall keep records as specified in the monitoring plan required by § 63.484(k). Paragraphs (d)(8) and (d)(9) of this section specify documentation requirements.

(1) The monitoring system shall measure data values at least once every 15 minutes.

(2) The owner or operator shall record either each measured data value or block average values for 1 hour 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. Owners or operators of batch front-end process vents shall record each measured data value.

(3) Daily average (or batch cycle daily average) values of each continuously monitored parameter shall be calculated for each operating day as specified in paragraphs (d)(3)(i) through (d)(3)(ii) of this section, except as specified in paragraphs (d)(6) and (d)(7) of this section.

(i) The daily average value or batch cycle daily average shall be calculated as the average of all parameter values recorded during the operating day, except as specified in paragraph (d)(7) of this section. For batch front-end process vents, as specified in § 63.491(e)(2)(i), only parameter values measured during those batch emission episodes, or portions thereof, in the batch cycle that the owner or operator has chosen to control shall be used to calculate the average. The calculated average shall cover a 24-hour period if operation is continuous, or the number of hours of operation per operating day if operation is not continuous.

(ii) The operating day shall be the period that the owner or operator specifies in the operating permit or the Notification of Compliance Status for purposes of determining daily average values or batch cycle daily average values of monitored parameters.

(4) -(5) [Reserved]

(6) If all recorded values for a monitored parameter during an operating day are above the minimum level or below the maximum level established in the Notification of Compliance Status or operating permit, the owner or operator may record that all values were above the minimum level or below the maximum level rather than calculating and recording a daily average (or batch cycle daily average) for that operating day.

(7) Monitoring data recorded during periods identified in paragraphs (d)(7)(i) and (ii) of this section shall not be included in any average computed under this subpart. Records shall be kept of the times and durations of all such periods and any other periods during process or control device or recovery device operation when monitors are not operating.

(i) Monitoring system breakdowns, repairs, calibration checks, and zero (low-level) and high-level adjustments; or

(ii) Periods of non-operation of the affected source (or portion thereof), resulting in cessation of the emissions to which the monitoring applies.

(8) For continuous monitoring systems used to comply with this subpart, records documenting the completion of calibration checks, and records documenting the maintenance of continuous monitoring systems that are specified in the manufacturer's instructions or that are specified in other written procedures that provide adequate assurance that the equipment would reasonably be expected to monitor accurately.

(9) The owner or operator of an affected source granted a waiver under § 63.10(f) shall maintain the information, if any, specified by the Administrator as a condition of the waiver of recordkeeping or reporting requirements.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(3) For storage vessels, the requirements specified in § 63.484(t) and § 63.506(e)(4)(ii)(F)(6).

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

(t) Owners and operators of affected sources must make the substitutions as specified in paragraphs (t)(1) through (4) of this section:

(1) Substitute “For each affected source as described in § 63.480” for each occurrence of the phrase “For each source as defined in § 63.101”.

(2) Substitute “beginning no later than the compliance dates specified in § 63.481(n)” for each occurrence of the phrase “beginning no later than the compliance dates specified in § 63.100(k)(10)”.

(3) Substitute “owners and operators of affected sources as described in § 63.480” for each occurrence of the phrase “owners and operators of sources as defined in § 63.101”.

(4) Substitute “§ 63.508” for each occurrence of “§ 63.108”.

(t) Owners and operators of affected sources must make the substitutions as specified in paragraphs (t)(1) through (4) of this section:

(1) Substitute “For each affected source as described in § 63.480” for each occurrence of the phrase “For each source as defined in § 63.101”.

(2) Substitute “beginning no later than the compliance dates specified in § 63.481(n)” for each occurrence of the phrase “beginning no later than the compliance dates specified in § 63.100(k)(10)”.

(3) Substitute “owners and operators of affected sources as described in § 63.480” for each occurrence of the phrase “owners and operators of sources as defined in § 63.101”.

(4) Substitute “§ 63.508” for each occurrence of “§ 63.108”.

(t) Owners and operators of affected sources must make the substitutions as specified in paragraphs (t)(1) through (4) of this section:

(1) Substitute “For each affected source as described in § 63.480” for each occurrence of the phrase “For each source as defined in § 63.101”.

(2) Substitute “beginning no later than the compliance dates specified in § 63.481(n)” for each occurrence of the phrase “beginning no later than the compliance dates specified in § 63.100(k)(10)”.

(3) Substitute “owners and operators of affected sources as described in § 63.480” for each occurrence of the phrase “owners and operators of sources as defined in § 63.101”.

(4) Substitute “§ 63.508” for each occurrence of “§ 63.108”.

(t) Owners and operators of affected sources must make the substitutions as specified in paragraphs (t)(1) through (4) of this section:

(1) Substitute “For each affected source as described in § 63.480” for each occurrence of the phrase “For each source as defined in § 63.101”.

(2) Substitute “beginning no later than the compliance dates specified in § 63.481(n)” for each occurrence of the phrase “beginning no later than the compliance dates specified in § 63.100(k)(10)”.

(3) Substitute “owners and operators of affected sources as described in § 63.480” for each occurrence of the phrase “owners and operators of sources as defined in § 63.101”.

(4) Substitute “§ 63.508” for each occurrence of “§ 63.108”.

(o) All affected sources that commenced construction or reconstruction on or before April 25, 2023, must be in compliance with the chloroprene requirements in §§ 63.484(u), 63.485(y) and (z), 63.487(j), 63.494(a)(7), 63.501(a)(10)(iv), 63.502(a)(3) and (a)(7), 63.509, and 63.510 upon initial startup or on October 15, 2024, whichever is later. All affected sources that commenced construction or reconstruction after April 25, 2023, must be in compliance with the chloroprene requirements in §§ 63.484(u), 63.485(x) and (z), 63.487(j), 63.494(a)(7), § 63.501(a)(10)(iv), 63.502(q), 63.502(a)(3) and (a)(7), 63.509, and 63.510 upon initial startup, or on July 15, 2024, whichever is later.

(a) This section applies to each storage vessel that is assigned to an affected source, as determined by § 63.480(g). Except for those storage vessels exempted by paragraph (b) of this section, the owner or operator of affected sources shall comply with the requirements of §§ 63.119 through 63.123 and 63.148, with the differences noted in paragraphs (c) through (u) of this section, for the purposes of this subpart.

This section applies beginning no later than the compliance dates specified in § 63.481(o). In order to demonstrate compliance with the emission limits and work practice standards specified in § 63.485(y) (for continuous front-end process vents in chloroprene service), § 63.487(j) (for batch front-end process vents in chloroprene service), § 63.494(a)(7) (for back-end process vents in chloroprene service), § 63.484(u) (for storage vessels in chloroprene service), and § 63.501(a)(10)(iv) (for wastewater in chloroprene service), owners and operators must meet the requirements specified in paragraphs (a) and (b) of this section.

(u) For each affected source as described in § 63.480, beginning no later than the compliance dates specified in § 63.481(o), if the storage vessel (of any capacity and vapor pressure) stores liquid containing chloroprene such that the storage vessel is considered to be in chloroprene service, as defined in § 63.482, then the owner or operator must comply with the requirements of paragraphs (u)(1) through (3) of this section in addition to all other applicable requirements specified in § 63.483 and elsewhere in this section.

(1) Reduce emissions of chloroprene by venting emissions through a closed vent system to a non-flare control device that reduces chloroprene by greater than or equal to 98 percent by weight, or to a concentration less than 1 ppmv for each storage vessel vent. If a combustion device is used, the chloroprene concentration of 1 ppmv must be corrected to 3 percent oxygen.

(2) To demonstrate compliance with the emission limits specified in paragraph (u)(1) of this section for storage vessels in chloroprene service, owners and operators must meet the requirements specified in § 63.510.

(3) Owners and operators must keep the records specified in paragraphs (u)(3)(i) and (u)(3)(ii) of this section in addition to those records specified elsewhere in this section.

(i) For storage vessels in chloroprene service, records of the concentration of chloroprene of the fluid stored in each storage vessel.

(ii) The owner or operator must keep records of all periods during which operating values are outside of the applicable operating limits specified in § 63.510(b)(4) through (6) when regulated material is being routed to the non-flare control device. The record must specify the operating parameter, the applicable limit, and the highest (for maximum operating limits) or lowest (for minimum operating limits) value recorded during the period.

(u) For each affected source as described in § 63.480, beginning no later than the compliance dates specified in § 63.481(o), if the storage vessel (of any capacity and vapor pressure) stores liquid containing chloroprene such that the storage vessel is considered to be in chloroprene service, as defined in § 63.482, then the owner or operator must comply with the requirements of paragraphs (u)(1) through (3) of this section in addition to all other applicable requirements specified in § 63.483 and elsewhere in this section.

(1) Reduce emissions of chloroprene by venting emissions through a closed vent system to a non-flare control device that reduces chloroprene by greater than or equal to 98 percent by weight, or to a concentration less than 1 ppmv for each storage vessel vent. If a combustion device is used, the chloroprene concentration of 1 ppmv must be corrected to 3 percent oxygen.

(2) To demonstrate compliance with the emission limits specified in paragraph (u)(1) of this section for storage vessels in chloroprene service, owners and operators must meet the requirements specified in § 63.510.

(3) Owners and operators must keep the records specified in paragraphs (u)(3)(i) and (u)(3)(ii) of this section in addition to those records specified elsewhere in this section.

(i) For storage vessels in chloroprene service, records of the concentration of chloroprene of the fluid stored in each storage vessel.

(ii) The owner or operator must keep records of all periods during which operating values are outside of the applicable operating limits specified in § 63.510(b)(4) through (6) when regulated material is being routed to the non-flare control device. The record must specify the operating parameter, the applicable limit, and the highest (for maximum operating limits) or lowest (for minimum operating limits) value recorded during the period.

(u) For each affected source as described in § 63.480, beginning no later than the compliance dates specified in § 63.481(o), if the storage vessel (of any capacity and vapor pressure) stores liquid containing chloroprene such that the storage vessel is considered to be in chloroprene service, as defined in § 63.482, then the owner or operator must comply with the requirements of paragraphs (u)(1) through (3) of this section in addition to all other applicable requirements specified in § 63.483 and elsewhere in this section.

(1) Reduce emissions of chloroprene by venting emissions through a closed vent system to a non-flare control device that reduces chloroprene by greater than or equal to 98 percent by weight, or to a concentration less than 1 ppmv for each storage vessel vent. If a combustion device is used, the chloroprene concentration of 1 ppmv must be corrected to 3 percent oxygen.

(2) To demonstrate compliance with the emission limits specified in paragraph (u)(1) of this section for storage vessels in chloroprene service, owners and operators must meet the requirements specified in § 63.510.

(3) Owners and operators must keep the records specified in paragraphs (u)(3)(i) and (u)(3)(ii) of this section in addition to those records specified elsewhere in this section.

(i) For storage vessels in chloroprene service, records of the concentration of chloroprene of the fluid stored in each storage vessel.

(ii) The owner or operator must keep records of all periods during which operating values are outside of the applicable operating limits specified in § 63.510(b)(4) through (6) when regulated material is being routed to the non-flare control device. The record must specify the operating parameter, the applicable limit, and the highest (for maximum operating limits) or lowest (for minimum operating limits) value recorded during the period.