Change ahead

Harold Laurence and Behdad Yazdani, Trinity Consultants, USA,

explain the EPA’s proposed revisions to emission standards for the gasoline distribution industry, and the implications for the storage sector.

On 10 June 2022, the US Environmental Protection Agency (EPA) proposed revisions to emission standards for the gasoline distribution industry.1 These standards affect storage tanks, loading racks, and equipment components in gasoline service at thousands of gasoline distribution terminals, bulk plants, and pipeline stations.2 The proposed revisions include several important increases in stringency, such as lower numeric emission limits, additional monitoring, and shorter averaging periods.

Background

The EPA has regulated volatile organic compound (VOC) emissions from the gasoline distribution sector under its New Source Performance Standards (NSPS) regulatory programme since the 1983 promulgation of ‘Standards of Performance for Bulk Gasoline Terminals’, Subpart XX.3 The NSPS requires most new and modified gasoline truck loading racks to meet an emission standard of 35 milligrams of total organic compounds (TOC) per litre of gasoline loaded (mg/L TOC).4 The NSPS requires monthly monitoring of loading rack equipment for leaks, by audio, visual, and olfactory (AVO), or ‘sight/sound/smell’ means.5 NSPS XX also

introduced vapour tightness requirements for gasoline tank trucks.6

In 1994, the EPA promulgated an emission standard regulating hazardous air pollutant (HAP) emissions from major source gasoline terminals and pipeline breakout stations: ‘National Emission Standards for Gasoline Distribution Facilities (Bulk Gasoline Terminals and Pipeline Breakout Stations)’, Subpart R.7 This subpart required gasoline truck and rail loading racks to meet 10 mg/L TOC.8 It required gasoline storage vessels (storage tanks) to install an internal floating roof (IFR) meeting most requirements of the storage tank NSPS,9 and to retrofit certain deck fittings on existing gasoline storage vessels with external floating roofs (EFRs).10 Subpart R required monthly AVO leak inspections, but the scope included all gasoline-service equipment at the terminal or breakout station.

Subpart R only affected larger terminals and breakout stations, those that met the EPA’s HAP major source threshold. By 1999, the EPA had indicated its intent to regulate gasoline distribution facilities that did not rise to the HAP major source threshold.11 In 2008, EPA promulgated ‘National Emission Standards for Hazardous Air Pollutants for Source Category: Gasoline Distribution Bulk Terminals, Bulk Plants, and Pipeline Facilities’, Subpart BBBBBB (Subpart 6B).12 Subpart 6B contained different sets of requirements for four source categories: bulk gasoline terminals, bulk gasoline plants (a throughput of less than 20 000 gal./d, pipeline pump stations, and pipeline breakout stations. Table 1 presents some key requirements of Subpart 6B.

Summary of revisions

EPA is required to review NSPS, such as Subpart XX, and National Emission Standards for Hazardous Air Pollutants (NESHAP), such as Subparts R and 6B, at least every eight years.13 If needed, the EPA must revise the subparts to reflect the best demonstrated system of emission reduction (for NSPS) or to take developments in control technology into account (for NESHAP, a ‘technology review’). Table 2 presents the EPA’s key proposed revisions of the three subparts. New or more stringent requirements for loading racks, storage tanks, and gasoline-service equipment are proposed. Finalised rule revisions, which may differ from the proposed revisions, are expected on or about June 2023. A three-year timeframe to reach compliance with Part 63 rules means that the Part 63, Subparts R and 6B changes would apply on or about 1 June 2026. Performance testing would occur within 180 days from that date.14

Certain aspects of the revisions to 40 CFR Part 60, Subpart XX, and 40 CFR Part 63, Subpart 6B merit further discussion.

Subpart XXa applicability date

Subpart XXa proposes much more stringent requirements for emission control devices on gasoline loading racks than the current Subpart XX. When such NSPS rules are revised, existing facilities come into compliance with the new rule only after the first time they are modified, or reconstructed, after the rule proposal date. Under NSPS rules, most changes to a facility that cause emissions to increase are ‘modification,’ and most changes that are more than 50% of the cost Table 1. Selected requirements of current Subpart 6B of an equivalent new Affected source type Equipment type Emission standard Subpart 6B facility are reference ‘reconstruction.’15 Most Bulk gasoline terminals, importantly, since the EPA published the proposed Pipeline breakout stations, Subpart XXa on Pipeline pumping stations 10 June 2022, a loading rack project that takes place after this date may cause the loading rack to become subject to the final rule text of Subpart XXa, even though the rule is not yet final at present. Terminal operators should carefully consider the effects and schedules of capital projects affecting their loading racks, to assess if those projects will cause the racks to be subject to Subpart XXa’s stringent new standards.

Gasoline storage vessel, either > 151 m3 (39 900 gal.), or 75 to 151 m3 (19 800 to 39 900 gal.) and throughput > 480 gpd Floating roof. IFR or EFR design. See Subpart 6B for detailed requirements Subpart 6B Table 1 Item 2

Other gasoline storage vessels Fixed roof tank. Maintain openings closed when not in use Table 1 Item 1

Gasoline loading racks, throughput > 250 000 gpd Vapour collection system. Reduce emissions to ≤ 80 mg/L TOC. Cargo tanks must be vapour tight Table 2 Item 1

Other gasoline loading racks Submerged filling Table 2 Item 2

Equipment in gasoline service Monthly AVO leak inspection §63.11086(c)

Bulk gasoline plant Gasoline storage vessel > 250 gal. Submerged fill pipe §63.11086(a)

Equipment in gasoline service General Monthly AVO leak inspection Spill minimisation; open container covering §63.11086(c)

§63.11086(d)

Instrument monitoring

Each of the proposed revised rules includes an

instrument monitoring programme to detect leaks from equipment in gasoline service. None of the current rules for gasoline distribution facilities require instrument monitoring. Even bulk gasoline plants with throughput less than 20 000 gal./d would be required to conduct instrument monitoring.16

The proposed programme includes two options. One option is a Leak Detection and Repair (LDAR) programme using EPA Method 21 to detect leaks as is common at petroleum refineries or chemical plants. The other option is to use Optical Gas Imaging (OGI) to detect leaks. OGI technology creates images of hydrocarbon gases, such as gasoline vapours. The proposed rules only differ in frequency of monitoring, as shown in Table 2.

First-time implementation of an instrument monitoring LDAR programme requires advance consideration of several factors. Inspection logs required under current rules must be replaced with detailed, individually identified components. Typically, component identifiers and monitoring results are stored in a dedicated LDAR compliance tool. A decision must also be made between selecting a contractor or training a terminal’s staff to provide routine monitoring. This decision would consider availability of contractors and of monitoring equipment.

Loading rack emission control device changes

The EPA’s proposed emission standard revisions to Subpart 6B are substantial for loading racks and associated vapour control systems at gasoline distribution facilities. According to the EPA, there are presently more than 9250 facilities in the US that are subject to Subpart 6B provisions.17

The current Subpart 6B specifies that bulk gasoline terminals loading racks with gasoline throughput of 250 000 gal./d or greater must reduce the emissions of TOC to less than or equal to 80 mg/L TOC. This emission

Table 2. Selected proposed requirements for Subpart XXa and Subparts R and 6B, for equipment at bulk gasoline terminals, pipeline pump stations, and pipeline breakout stations

Affected source type

Subpart a Current requirements (summary)

Vapour combustion units (VCUs) b XX, XXa XX: 35 mg/L TOC for truck racks new/modified after 17 December 1980 80 mg/L existing 6 hr avg

Vapour recovery units (VRUs) c R

6B

10 mg/L TOC 6 hr avg 80 mg/L TOC for racks > 250 000 gpd 6 hr avg XX, XXa Same as VCUs

Proposed requirements (summary)

• 1 mg/L TOC for new racks 3 hr avg • 10 mg/L for modified/reconstructed racks 3 hr avg

10 mg/L TOC 3 hr avg 35 mg/L TOC for racks > 250 000 gpd 3 hr avg

• 550 ppmv TOC as propane 3 hr avg at new racks • 5500 ppmv for modified/reconstructed racks

R Same as VCUs 5500 ppmv TOC as propane 3 hr avg

Open flares on loading racks d 6B Same as VCUs

XX/XXa, R, 6B General flare standards: §60.18 (XX) or §63.11(b) (R, 6B) 19 200 ppmv TOC as propane 3 hr avg XXa: no flares allowed for new racks Racks modified or reconstructed in XXa, or subject to R or 6B, may meet refinery flare rules at § 63.670(b)

Gasoline storage tanks subject to Subpart R or 6B standards e R, 6B IFR or EFR • See subparts for rim seal and deck fitting requirements • EFR tanks’ deck fittings must fully meet Part 60,

Subpart Kb • IFR tanks must conduct LEL monitoring during annual inspections • LEL threshold is 25%, 5-minute avg LEL data to be collected every 15 seconds for at least 20 minutes

Equipment in gasoline service f (also applies to bulk plants under 6B) XX/XXa, R, 6B Monthly AVO leak inspection, with leaks repaired

Method 21 leak monitoring or Optical Gas Imaging 10 000 ppm leak definition for Method 21 • XXa: Quarterly • R: Semiannual • 6B: Annual a. Subpart XX requirements are not revised in the present rulemaking. Existing loading racks would comply with Subpart XXa after they are modified or reconstructed, and Subpart XX until then. b. Current: §§ 60.502(a)-(b), 63.422(b), Subpart 6B Table 2 Item 1. Proposed: §§ 60.502a(b)(1), (c)(1), 63.422(b)(2), Subpart 6B Table 3 Item 1, docket EPA-HQ-OAR-2020-0371. c. Current: same as VCU. Proposed: §§ 60.502a(b)(2), (c)(2), Subpart 6B Table 3 Item 3, as proposed in docket EPA-HQ-OAR-2020-0371. d. Distinct from VCUs. Current: §§ 60.503(e), 3.425(a)(2), 63.11092(a)(4). Proposed: §§ 60.502a(c)(3), Subpart 6B Table 3 Item 2, docket EPA-HQOAR-2020-0371. e. Under Part 63, Subparts R and 6B, tanks < 75 m3 (19 800 gal.) are exempt. Under Subpart 6B only, tanks from 75 to 151 m3 (19 800 to 39 800 gal.) are also exempt, if the tank’s throughput is 480 gpd (annual average) or less. Current rules: §63.423(a)-(b); Subpart 6B Table 1 Item 2. Proposed: §§ 63.423(c), 63.425(j), Subpart 6B Table 1 Item 2. EPA-HQ-OAR-2020-0371. f. Current: §§ 60.502(j), 63.424, 63.11086(c), 63.11089; Proposed: §§ 60.502a(j), 63.424(c), 63.11089, as proposed in docket EPA-HQ-OAR-2020-0371.

standard is the same regardless of the type of vapour control system used. The standard excludes methane and ethane from TOC measurement.18

By contrast, the proposed Subpart 6B specifies that such bulk gasoline terminals will need to reduce emissions of TOC to the levels listed below, depending on the type of vapour control system used. And the revised standard does not explicitly exclude methane and ethane. n Thermal oxidation system other than a flare (e.g., vapour combustion unit): reduce emissions of

TOC to less than or equal to 35 mg/L TOC, to be operated as specified in the proposed 40 CFR 63.11092(e)(2). n Flare: achieve at least 98% reduction in emissions of

TOC by weight, to be operated as specified in the proposed 40 CFR 60.502a(c)(3). n Vapour recovery system: reduce emissions of TOC to less than or equal to 19 200 parts per million by volume (ppmv) as propane, determined on a 3 hr rolling average.

Alternative monitoring changes

Gasoline distribution facility operators may face several potential challenges when complying with the proposed Subpart 6B standards. One potential challenge is related to the removal of alternative monitoring provisions in the current Subpart 6B rule for a thermal oxidation system other than a flare, such as a vapour combustion unit (VCU). Presently, monitoring of the presence of a thermal oxidation system pilot flame is allowed as an alternative to measuring the firebox temperature to demonstrate compliance with the monitoring requirements of Subpart 6B.19 Gasoline vapours combust readily; for instance, butane has a net heating value (NHV) of 2985 Btu/ft3 .

20

The proposed rules disallow pilot flame monitoring as a compliance option. New loading racks subject to the proposed Subpart XXa would be required to monitor firebox temperature continuously.21 Loading racks subject to Subpart XXa due to modification or reconstruction, as well as racks subject to Subpart 6B, would have an additional option to monitor the NHV of the gases fed to the VCU. Such VCUs would follow rules for open flares at petroleum refineries.22

A temperature monitoring method could result in the need to combust additional auxiliary fuel during periods of low gasoline loading, to maintain the firebox temperature at or above the level determined during the performance test. Furthermore, some facilities use a VCU as a backup vapour control system to their primary vapour recovery system for when the primary vapour control system is down. If the backup VCU is required to combust additional auxiliary fuel to maintain the firebox temperature, operation of the backup vapour control system may become cost prohibitive.

Facility operators should begin to develop their compliance approaches for thermal oxidation systems such as VCUs. From the more limited options available in the proposed rules, facilities should select a vapour control and compliance demonstration approach that achieves compliance in a cost-effective manner.

Averaging period changes

The proposed rules also reduce the duration of averaging periods for loading rack emission control devices, creating another potential compliance challenge. For thermal oxidation systems other than a flare, the EPA is proposing that combustion zone temperature be maintained at or above the level determined during the performance test on a 3 hr rolling average basis. Similarly, the EPA is proposing a 3 hr rolling average monitoring period for the ppmv emission standards for vapour recovery systems. The current averaging period for performance testing for either type of control device is six hours. The change from a 6 hr to a 3 hr rolling average would impact design and operation of control devices.

In thermal oxidation systems such as VCUs, firebox temperature is related to the volume of gasoline vapours combusted at a given time. At most facilities, loading activities do not occur at a uniform rate throughout the day but are, rather, characterised by periods of higher or lower gasoline demand. On a shorter, 3 hr average, facilities would record greater variability in the VCU temperature. Changes in temperature due to varying gasoline vapour generation rate would not necessarily correlate with control device efficacy. Even so, operators would have a compliance need to stay above the required temperature minimum, such as by adding assist gas, shortening periods of higher loading rates, or smoothing periods of peak and low demand. This compliance need could result in capital costs, truck waiting time, and/or delivery delays.

In vapour recovery systems, a limit expressed as ppmv on a 3 hr basis is more stringent than the same limit expressed on a 6 hr basis. Facilities’ existing vapour recovery systems may need to be redesigned to be able to accommodate the proposed emission limit of 19 200 ppmv as propane on a 3 hr rolling average basis.

Preparing for the changes

The EPA has proposed substantial changes to air emission standards for the gasoline distribution industry. The proposed revisions include instrument monitoring LDAR requirements, revised monitoring requirements for storage vessels, and stricter emission standards for loading racks. The proposed standards may require affected facilities to undertake capital projects, to implement new compliance demonstration programmes, or to conduct internal feasibility studies for compliance planning. Gasoline distribution facilities should begin developing compliance strategies for the revised rules, especially as NSPS rules apply to facilities modified after the proposed rule date.

Note

For a full list of references, please visit www.tanksterminals.com/product-news/01092022/ change-ahead--references/