October 4, 2006

Sent via E-Mail

McDonald.Randy@epa.com

Regarding: Vapor Balancing Provisions of the National Emission Standards for Hazardous 

Air pollutants from the Synthetic Organic Chemical Manufacturing Industry and Other 

Processes Subject to the Negotiated Regulation for Equipment Leaks 

Related to: Docket ID Number EPA-HQ-OAR-2005-0475; National Emission Standard for 

Hazardous Air Pollutants for Organic Hazardous Air Pollutants from the Synthetic Organic 

Chemical Manufacturing Industry

Dear Mr. McDonald:

On December 23, 2004, EPA issued direct final rule amendments to the National Emission 

Standards for Hazardous Air pollutants from the Synthetic Organic Chemical Manufacturing 

Industry (HON) and Other Processes Subject to the Negotiated Regulation for Equipment Leaks. 

Specifically, EPA adopted amendments that allowed the use of vapor balancing as a control 

technique for storage tanks. In doing so, EPA also required that certain actions were required of 

facilities that are neither subject to the HON nor any other Maximum Achievable Control 

Technology standard. 

The Dow Chemical Company (Dow), as an owner and operator of numerous synthetic organic 

chemical facilities throughout the United States (US), is hereby submitting comments concerning 

the vapor balancing provisions of the HON. Although not directly related to the HON Residual 

Risk Rule proposal, the timing for making changes to the HON regulation is appropriate while 

the rule is being addressed. If EPA cannot address these comments as part of the residual risk 

amendments, it may be feasible and acceptable for EPA to address these vapor balancing 

comments as a direct final rule as was done when the vapor balancing provisions were first 

promulgated in the December 23, 2004 amendments.

Dow believes that vapor balancing emissions generated during storage tank filling operations 

back to the delivery vehicle (rail car, tank truck, marine vessel) is an effective “control 

technology” for controlling storage tank working loss emissions. There are virtually no 

emissions generated at the source during vapor balancing. The owner or operator of storage 

tanks in which working loss emissions are controlled via vapor balancing should be exempt from 

any further control, recordkeeping or reporting requirements in the rule applicable to that storage 

tank. In addition, EPA should not impose any further emission reduction, recordkeeping or 

reporting requirements on reloading / cleaning facilities. 

For this reason, Dow recommends that EPA eliminate the vapor balancing provisions in 

63.119(g) all together and not impose any additional requirements on the vapors remaining in the 

delivery vehicle, either at the time of transfer or when the vehicle leaves the HON process unit to 

be returned to the reloading / cleaning facility.
The Dow Chemical Company Page 2 of 12 Comments Concerning HON Vapor Balancing 

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The attached comments further explain Dow’s position on this issue. Should EPA choose to 

keep the vapor balancing provisions in HON, Dow is suggesting alternative language to improve 

the usability and flexibility of these provisions. 

Thank you in advance for your consideration of our comments. If you have questions, 

concerning the following comments, please contact me at (225) 353-8844 or email me at 

balexius@dow.com.

Sincerely,

Bruce J. Alexius

EH&S Operations Regulatory Management

The Dow Chemical Company

P. O. Box 150, Building 3502

Plaquemine, LA 70765-0150
The Dow Chemical Company Page 3 of 12 Comments Concerning HON Vapor Balancing 

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Vapor Balancing Provisions of the National Emission Standard for Hazardous Air 

Pollutants for Organic Hazardous Air Pollutants from the Synthetic Organic Chemical 

Manufacturing Industry

The Dow Chemical Company (Dow) thanks EPA for consideration of comments relative to the 

vapor balancing provisions of the National Emission Standard for Hazardous Air Pollutants for 

Organic Hazardous Air Pollutants from the Synthetic Organic Chemical Manufacturing Industry. 

Dow strongly believes that reducing regulatory burden or eliminating regulatory hurdles

associated with emission controls is a highly effective way of promoting the employment of 

emission reduction strategies. 

In addressing the vapor balancing requirements of the HON, Dow maintains that:

1. Vapor balancing during tank filling operations creates virtually no emissions to the 

atmosphere at the source. Storage tanks using vapor balancing for tank filling operations

should be exempt from the storage tank provisions in the rule and any associated 

recordkeeping and reporting requirements. There is no basis for regulating an activity

that has no associated emissions. Therefore, it is not necessary to include vapor balancing 

in the regulatory text to address working loss emissions. Note: Any breathing losses 

from the storage tank would still be subject to the storage vessel provisions.

2. Reloading / cleaning operations located at areas sources or outside of the United States 

should not be regulated under MACT rules that apply to U.S. plant sites located at major 

sources as defined in section 112(a) of the Act. Reloading / cleaning operations still must 

comply with state and/or local requirements for reloading and cleaning. In addition, 

reloading facilities in the U.S. that are located at major sources are properly regulated 

under the Organic Liquids Distribution source category if reloading an organic liquid 

containing > 5% Table 1 OHAP, as defined in 40 CFR 63 Subpart EEEE. 

3. If EPA chooses to maintain vapor balancing provisions complete with requirements for 

reloading / cleaning facilities, then Dow proposes language that will make the HON, 

Pharma MACT and PAIP MACT more flexible. Please note that several MACT 

standards such as P&R I, P&R IV, Polyether Polyol MACT, etc. reference the HON for 

storage tank control options. The recommendations outlined in these comments will also 

improve the flexibility in these rules.
The Dow Chemical Company Page 4 of 12 Comments Concerning HON Vapor Balancing 

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Discussion

There are virtually no emissions from vapor balancing itself and no additional emissions 

from tank cars as compared to unloading without vapor balancing. Dow maintains that 

whether vapor balancing has been employed or not during an offloading operation, the 

transport vehicle is left with a saturated vapor space that contains the same amount of 

residual HAP content. 

The following illustrations depict normal unloading operations to further demonstrate the point. 

In the illustrations below, a typical unloading operation is depicted. Rather than draw identical 

pictures, one showing a vapor recovery line and one showing a line to a control device such as a 

flare from the top of the storage tank, the lines are depicted on one drawing to be concise. Please 

note that the only difference between Figure 1 and Figure 2 is that the rail car is full in the case 

of Figure 1 and “empty’ in the case of Figure 2.
Rail Car

Storage Tank A

Load Line

Line to Control Device

Vapor Return Line

Pump

Figure 1

Flare
The Dow Chemical Company Page 6 of 12 Comments Concerning HON Vapor Balancing Requirements

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Rail Car

Storage Tank A

Load Line

Line to Control Device

Vapor Return Line

Flare

Pump

Figure 2
When using a standard pump to unload a transport vehicle such as a rail car, the pump will draw 

down the liquid level in the car until the point where the pump no longer has sufficient suction 

head (level of liquid above the pump suction) to continue pumping. At this stage in time, 

pumping is discontinued leaving a slight level of liquid in the transport vehicle. The vapor space 

above the liquid is saturated with the chemical being unloaded and remains saturated unless 

extraordinary means are taken to evacuate or wash the car. In fact, even with a “full” car of 

liquid, there must be a vapor space and this vapor space is saturated with the chemical being 

unloaded. 

It does not matter whether vapors from the storage are being returned to the transport vehicle 

during the unloading process or whether the vapors from the storage tank are being directed to a 

control device. When liquid transfer is complete, regardless of how the vapors were handled 

during transfer, the transport vehicle is left with the same amount of residual chemical in the 

vehicle. The amount in the vapor space is equivalent to how much chemical the vapor space can 

contain at the given pressure and temperature of the vehicle being unloaded. Therefore, there is 

no technical reason for regulatory differentiation between unloading with vapor recovery and 

unloading while directing vapors to a control device. 

Additional certifications required under the current HON language for the cases discussed above 

have no technical basis and only serve to discourage the use of vapor balancing which essentially 

has no emissions during the unloading process. EPA should remove the requirements that may

discourage vapor balancing and actually promote the use of this very effective technology.

Should EPA decide to keep the vapor balancing provisions, then the following changes would 

provide additional flexibility to improve the usability of these provisions.

(A) The HON should be updated to exclude off-site reloading / cleaning facilities from 

additional notification and reporting obligation. 

Section 63.119(g)(7)(ii) of HON requires compliance with §§63.119 through 63.123 of HON. 

Section 63.122(c) requires submittal of a Notification of Compliance Status and 63.122(g) 

contains periodic reporting requirements for storage tanks using a closed vent system and control 

device. Therefore, if the reloading / cleaning facility chooses to use a closed vent system and 

control device to reduce emissions of HAP by 95% by weight or greater in accordance with 

63.119(g)(6)(i), then Dow assumes that the reloading / cleaning facility will be subject to all 

notification and reporting obligations contained or referenced within §§63.119 through 63.123. 

Both the MON and the OLD MACT were recently amended to exclude the owner or operator of 

the reloading / cleaning facility from any notification or periodic reporting obligation other than 

the initial certification.

 The MON was amended on July 14, 2006 [71 FR 40316]. In the Preamble on page 40318, 

EPA states: The final amendments eliminate reporting requirements for offsite cleaning and 

reloading facilities that control emissions from rail cars and tank trucks that are used in 

vapor balancing for storage tanks at the affected source. Section 63.2470(e)(2)(i) states that 
The Dow Chemical Company Page 8 of 12 Comments Concerning HON Vapor Balancing 

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“The reporting requirements in 63.2520 do not apply to the owner or operator of the offsite 

cleaning or reloading facility.”

 The vapor balancing option was recently added to the OLD MACT as part of the July 28, 

2006 amendments [71 FR 42898]. The OLD MACT excludes the owner or operator of the 

offsite reloading / cleaning facility from the notification requirements and the reporting 

requirements. Section 63.2346(a)(4)(vii)(B) states: “(B) If complying with paragraph 

(a)(4)(vi)(A) of this section, comply with the requirements for a closed vent system and 

control device as specified in this subpart EEEE. The notification requirements in §63.2382 

and the reporting requirements in §63.2386 do not apply to the owner or operator of the 

offsite cleaning or reloading facility.”

Therefore, Dow requests that EPA waive all notification / reporting obligations referenced in 

§63.122 imposed on the facilities reloading and/or cleaning transport vehicles that have been 

vapor balanced at process units subject to HON.

Dow recommends that the following language be added to 63.119(g)(7)(ii) that states: 

“(7) The owner or operator of the facility where the railcar, tank truck, or barge is reloaded or 

cleaned must comply with paragraphs (g)(7)(i) through (iii) of this section.

(i)...

(ii) If complying with paragraph (g)(6)(i) of this section, comply with the 

requirements for a closed vent system and control device specified in §§63.119 

through 63.123. The notification and reporting requirements in §63.122 do not 

apply to the owner or operator of the offsite cleaning or reloading facility.”

(B) The HON should be updated to allow off-site reloading / cleaning facilities to comply 

with other Part 63 standards.

The MON and the OLD MACT also now allow the reloading / cleaning facility to comply with 

other applicable Part 63 NESHAPs - and not just the MON or OLD MACT.

 In the final amendments to the MON promulgated on July 14, 2006, EPA states in the 

Preamble: “The final amendments eliminate reporting requirements for offsite cleaning 

and reloading facilities that control emissions from rail cars and tank trucks that are used 

in vapor balancing for storage tanks at the affected source. For an offsite cleaning or 

reloading facility that is subject to any other NESHAP under 40 CFR part 63, the final 

amendments specify that compliance with the monitoring, recordkeeping, and reporting 

requirements in the other rule demonstrates compliance with the requirements in subpart 

FFFF of 40 CFR part 63. [71 FR 40318]

Section 63.2535(a)(2) of the MON states: “2) After the compliance dates specified in 

§63.2445, at an offsite reloading or cleaning facility subject to §63.1253(f), as referenced 

from §63.2470(e), compliance with the monitoring, recordkeeping, and reporting 

provisions of any other subpart of this part 63 constitutes compliance with the 
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monitoring, recordkeeping, and reporting provisions of §63.1253(f)(7)(ii) or 

§63.1253(f)(7)(iii). You must identify in your notification of compliance status report 

required by §63.2520(d) the subpart of this part 63 with which the owner or operator of 

the offsite reloading or cleaning facility complies.

 Section 63.2346(a)(4)(vii)(D) of the OLD MACT states: “After the compliance dates 

specified in §63.2342, at an offsite reloading or cleaning facility subject to 

§63.2346(a)(4), compliance with the monitoring, recordkeeping, and reporting provisions 

of any other subpart of this part 63 that has monitoring, recordkeeping, and reporting 

provisions constitutes compliance with the monitoring, recordkeeping and reporting 

provisions of §63.2346(a)(4)(vii)(B) or §63.2346(a)(4)(vii)(C). You must identify in your 

notification of compliance status report required by §63.2382(d) the subpart of this part 

63 with which the owner or operator of the offsite reloading or cleaning facility

complies.” [Added July 28, 2006, 71 FR 42908]

Therefore, Dow requests that EPA add a similar overlap provision to HON to allow the reloading 

/ cleaning facility to comply with other Part 63 standards in lieu of the HON or the subpart 

referencing HON.

Dow recommends that EPA add the following paragraph as a new section in 63.119(g)(7)(iv) 

that states: 

“After the compliance dates specified in §63.100(k) or the referencing Part 63 

NESHAP at a reloading or cleaning facility subject to §63.119(g)(6)-(g)(7), compliance 

with the monitoring, recordkeeping, and reporting provisions of any other subpart of 

this part 63 that has monitoring, recordkeeping, and reporting provisions constitutes 

compliance with the monitoring, recordkeeping and reporting provisions of 

§63.119(g)(7)(ii) or §63.119(g)(7)(iii). You must identify in your notification of 

compliance status report required by §63.152(b) or notification of compliance status 

report of the Part 63 NESHAP referencing Subpart G, the Part 63 subpart with which 

the owner or operator of the reloading or cleaning facility complies.”

(C) Flexibility should be written into the HON concerning U.S. Department of 

Transportation certifications of railcars and tank trucks.

The vapor balancing provisions of HON, Section 63.119(g)(2) requires that (2) Tank trucks and 

railcars must have a current certification in accordance with the U.S. Department of 

Transportation pressure test requirements of 49 CFR part 180 for tank trucks and 49 CFR 173.31 

for railcars. Barges must have a current certification of vapor-tightness through testing in 

accordance with 40 CFR 63.565.
The Dow Chemical Company Page 10 of 12 Comments Concerning HON Vapor Balancing 

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Section 63.123(i)(1) further requires that: “

(i) An owner or operator who elects to comply with §63.119(g) shall keep the records 

specified in paragraphs (i)(1) through (3) of this section. 

(1) A record of the U.S. Department of Transportation certification required by

§63.119(g)(2).”

The transfer rack provisions of HON have a similar requirement related to DOT certification that 

states: 

“(e) For each Group 1 transfer rack the owner or operator shall load organic HAP's into 

only tank trucks and railcars which: 

(1) Have a current certification in accordance with the U. S. Department of 

Transportation pressure test requirements of 49 CFR part 180 for tank trucks and 

49 CFR 173.31 for railcars; or 

(2) Have been demonstrated to be vapor-tight within the preceding 12 months, as 

determined by the procedures in §63.128(f) of this subpart. Vapor-tight means 

that the truck or railcar tank will sustain a pressure change of not more than 750 

pascals within 5 minutes after it is pressurized to a minimum of 4,500 pascals.”

However, the transfer rack recordkeeping provisions in 63.130(e) provide much greater 

flexibility on the various methods of verification that can be used. Section 63.130(e) 

provides that:

“The owner or operator of a Group 1 transfer rack shall record that the verification of DOT 

tank certification or Method 27 testing, required in §63.126(e) of this subpart, has been 

performed. Various methods for the record of verification can be used, such as: A check off 

on a log sheet; a list of DOT serial numbers or Method 27 data; or a position description for 

gate security, showing that the security guard will not allow any trucks on site that do not 

have the appropriate documentation.

Obtaining copies of the actual U.S. DOT certifications from suppliers can be very burdensome 

especially if the rail cars or tank trucks are not dedicated to a particular facility. EPA should add 

flexibility to the vapor balancing provisions of HON in 63.119(g) to allow various methods for 

the record of verification for DOT tank certification.

Dow recommends that amend the language in 63.123(i)(1) as follows:

(i) An owner or operator who elects to comply with §63.119(g) shall record that the 

verification of DOT tank certification, required in §63.119(g)(2) of this subpart, has been 

performed. Various methods for the record of verification can be used, such as: A check 

off on a log sheet; a list of DOT serial numbers or Method 27 data; or a position 
The Dow Chemical Company Page 11 of 12 Comments Concerning HON Vapor Balancing 

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description for gate security, showing that the security guard will not allow any trucks on 

site that do not have the appropriate documentation.

(D) EPA does not have the authority to impose Part 63 NESHAP requirements on a facility 

that is not a major source of HAP emissions, that is not inclusive in a source category being 

addressed by a standard, and that is not a facility located in the United States.

Under 40 CFR § 63.119(g) the owner or an operator of the facility where the railcar or tank truck 

is reloaded or cleaned after vapor balancing is subject to the Maximum Achievable Control 

Technology (“MACT”) requirements under the HON. See 40 CFR §§ 63.119(g)(6) and (7). 

The EPA is also imposing MACT requirements for the same type of facilities under other 

NESHAPs where vapor balancing is a control option. Imposing MACT requirements on these 

sources is outside of EPA’s authority under the Clean Air Act (CAA) for three reasons.

First, the majority of these cleaning or reloading facilities are area sources and EPA doesn’t have 

the authority to impose MACT requirements on area sources. Under §112(d) of the CAA, the 

EPA has the authority to impose on new and existing major sources the maximum degree of 

reduction which for new sources may not be less stringent than the emission control that is 

achieved in practice by the best controlled similar source. This type of emission control 

technology is the MACT. However, for area sources MACT doesn’t apply. EPA only has 

authority under § 112(d)(5) of the CAA to promulgate emission standards for area sources which 

provide for the use of generally available control technologies (GACT) or management practices. 

Applying MACT standards for area sources is outside of EPA CAA authority.

Second, EPA has the authority only to promulgate emission standards under § 112(d) of the 

CAA for sources listed in each category or subcategory identified under § 112(c). Further, EPA 

cannot apply the emissions standards promulgated for one source category to another category of 

sources without performing an additional MACT analysis under §§ 112(d)(2) and (3). However, 

that is exactly what has occurred with the vapor balancing option under the HON and other 

NESHAPs. 

The EPA under the HON vapor balancing option applies the MACT requirements promulgated 

for HON sources to non-HON sources. The HON applies to chemical manufacturing process 

units (CMPUs) that are located at major sources and manufacture as a primary product a SOCMI

chemical. See 40 CFR § 63.100(b). Under the vapor balance option, the EPA has applied the 

HON standards to cleaning or reloading facilities which generally don’t manufacture anything 

much less SOCMI chemicals. Additionally, there is a category for reloading facilities for which 

EPA chose to regulate only major sources, not area sources, for certain HAPs under the OLD 

MACT. EPA, if it wishes to properly regulate area sources that are cleaning and reloading 

facilities, must perform a GACT analysis and propose the rule for public comment. EPA has 

done neither. 

Third, some of the cleaning and reloading facilities used by Dow are located outside of the 

United States. EPA is imposing under the vapor balance option, MACT requirements to area 

sources which are outside of its regulatory reach. The CAA provides a program to enhance and 
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protect the quality of the Nation’s air resources. While Congress has adopted and incorporated 

into the CAA international treaties, such as the Montreal Protocol, it was never Congress’s intent 

to extend its national air program to international borders. Therefore, EPA has no authority to 

require facilities located outside the United States to certify compliance with a § 112(d) emission 

standard. 

(E) Reloading / cleaning facilities should not have to amend their Title V permits to 

indicate that they are now subject to the vapor balancing provisions of a Part 63 NESHAP 

applicable to their customers.

Many reloading / cleaning facilities will not have Title V permits to amend as they are not major 

sources of emissions nor or they subject to U. S. based regulations. However, should a reloading 

/ cleaning facility have a Title V permit, it should not be required to amend the permit to indicate 

that they are now subject to the vapor balancing provisions of a Part 63 NESHAP applicable to 

their customers. Part 63 standards are applicable to source categories as defined by EPA and 

driven by section 112 (d) of the Clean Air Act. EPA does not have the authority to regulate 

sources that are not applicable nor part of the source category being regulated. 

EPA has stated that vapor balancing increases the amount of chemical left in the transport and 

therefore it is appropriate that requirements be added to the reloading / cleaning facilities as the 

source category is responsible for increased emissions at the reloading / cleaning facilities. As 

illustrated above in the technical discussion, there are no additional emissions from the transport 

vehicle due to using vapor balancing. Hence, it is inappropriate for these facilities to be 

governed by a part 63 NESHAP and further inappropriate that the reloading / cleaning facility

include any such provisions in their Title V permit.