SOUTH COAST AIR QUALITY MANAGEMENT DISTRICT 

ATTACHMENT F 

Final Staff Report 

PROPOSED AMENDED RULE 1149 – STORAGE TANK AND PIPELINE CLEANING 

AND DEGASSING 

Dated: April 2008 

Deputy Executive Officer 

Planning, Rule Development, and Area Sources 

Elaine Chang, Dr.PH 

Assistant Deputy Executive Officer 

Planning, Rule Development, and Area Sources 

Laki Tisopulos, Ph.D., P.E. 

Planning and Rules Manager 

VOC Rule Development 

Larry M. Bowen, P.E. 

Author: Mike Morris AQ Specialist 

Reviewed by: Ed Muehlbacher, P.E. Program Supervisor 

 John Olvera Senior Deputy District Counsel 

 Barbara Baird Principal Deputy District Counsel 

 

Contributors Roger Christopher Supervising AQ Inspector 

 Hassan Namaki AQ Engineer II 

 Eugene Teszler AQ Specialist 

 Sam Vergara Supervising AQ Inspector 

 Rafael Reynosa Supervising AQ Inspector 
SOUTH COAST AIR QUALITY MANAGEMENT DISTRICT 

GOVERNING BOARD 

Chairman: WILLIAM A. BURKE, Ed.D. 

Speaker of the Assembly Appointee 

Vice Chairman: S. ROY WILSON, Ed.D. 

Supervisor, Fourth District 

Riverside County Representative 

MEMBERS:

MICHAEL D. ANTONOVICH 

Supervisor, Fifth District 

Los Angeles County Representative 

MICHAEL A. CACCIOTTI 

Mayor, City of South Pasadena 

Cities of Los Angeles County, Eastern Region 

BILL CAMPBELL 

Supervisor, Third District 

Orange County Representative 

JANE W. CARNEY 

Senate Rules Committee Appointee 

RONALD O. LOVERIDGE 

Mayor, City of Riverside 

Cities Representative, Riverside County 

JOSEPH K. LYOU, PH.D. 

Governor’s Appointee 

GARY OVITT 

Supervisor, Fourth District 

San Bernardino County Representative 

JAN PERRY 

Councilmember, 9th District 

City Representative, City of Los Angeles County 

MIGUEL PULIDO 

Mayor, City of Santa Ana 

Cities Representative, Orange County 

TONIA REYES URANGA 

Councilmember, City of Long Beach 

Cities of Los Angeles County, Western Region 

DENNIS YATES 

Mayor, City of Chino 

Cities Representative, San Bernardino County 

EXECUTIVE OFFICER

BARRY R. WALLERSTEIN, D.Env. 
TABLE OF CONTENTS 

Section Page 

Executive Summary 1 

Regulatory Background 1 

Operational Background 3 

Proposed Amendments 7 

Emission Inventory 10 

Emission Reductions 14 

Cost and Cost-Effectiveness 16 

Incremental Cost-Effectiveness and Analyses of Alternative Control Measures 18 

Voluntary Greenhouse Gas Reduction Quantification Protocol 19 

Comments and Response 20 

Comparative Analysis 28 

Socioeconomic Assessment 29 

California Environmental Quality Act (CEQA) 29 

Draft Findings under the California Health and Safety Code 29 

References 29 

APPENDIX A – Tank Degassing Logs 

APPENDIX B – Time to Complete Degassing
Final Staff Report ________________________________

Proposed Amended Rule 1149 1 April 2008

EXECUTIVE SUMMARY

Rule 1149 – Storage Tank Cleaning and Degassing was originally adopted by the South Coast 

Air Quality Management District (AQMD) on December 4, 1987 and subsequently amended on 

April 1, 1988 and July 14, 1995. 

Rule 1149 applies to VOC emissions from cleaning and degassing operations in large 

aboveground petroleum storage tanks at petroleum refineries and terminals and small 

underground gasoline storage tanks. The current regulation requires vapors contained in storage 

tanks to be vented to a control device for a pre-determined length of time or to be displaced by a 

liquid into a control device. 

The proposed rule amendments will instead require a vapor concentration of 5,000 ppmv, 

measured as methane, to be met before allowing the vapors to be vented to atmosphere. This 

proposed standard will better capture emissions from sludge and product residual remaining in 

the tanks. Liquid balancing, or any other technology that achieves the proposed standard will be 

allowed. 

The proposed rule amendments will also expand its applicability to small above ground gasoline 

storage tanks, pipelines and large storage tanks previously exempted because of lower vapor 

pressure products. Furthermore, the proposed amendments will streamline the notification 

process and clarify requirements for vacuum trucks and containers used for storing liquid and 

sludge removed during the cleaning process. 

If approved, the proposed rule amendments would fully implement control measure FUG-04 in 

the 2007 Air Quality Management Plan. 

As proposed, the rule would reduce VOC emissions by between 1.27 and 1.97 tons per day if the 

VOC vapors in the storage tank are completely saturated at an estimated annual cost between of 

$6.1 million dollars. The overall cost per ton of VOC reduced by the proposed amendment is 

estimated to be $13,159 based upon the expected emission reduction of 1.27 tons of VOC per 

day. 

Many degassing operations routinely achieve in practice the proposed requirements set forth in 

the proposed rule. California Code of Regulations, Title 8 - General Industry Safety Orders has 

strict restrictions for entry into confined spaces with hazardous atmospheres such as petroleum 

storage tanks. In order to avoid the restrictions, many facilities vent the vapors contained in the 

storage tanks into a control device until the tank interior is no longer considered a hazardous 

atmosphere and the proposed rule requirements would be met. Additionally, concern for nearby 

schools and residences as well as the potential for Rule 402 – Nuisance violations keeps facilities 

from discharging odorous VOC emissions. 

A quantification protocol is included in the proposed amendment to quantify Greenhouse gas 

reductions. The provision in Proposed Amended Rule (PAR) 1149 is voluntary and limited to the 

control of methane emissions from the degassing of natural gas pipelines, which is currently 

exempt from the requirements of the rule. Efforts to limit methane emissions from natural gas 

pipeline repair and maintenance activities will allow companies to reduce Greenhouse gas 

emissions. 

REGULATORY BACKGROUND

In 1987, Rule 1149 – Storage Tank Cleaning and Degassing was adopted to reduce VOC 

emissions from degassing operations of stationary storage tanks. The Standard Industrial 
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Proposed Amended Rule 1149 2 April 2008

Classification codes for applicable facilities include crude petroleum and natural gas (SIC code 

1311), paints, varnishes, lacquers, enamels, and allied products (SIC code 2851), cyclic organic 

crudes and intermediates, and organic dyes and pigments (SIC Code 2865), industrial organic 

chemicals, not elsewhere classified (SIC code 2869), petroleum refining (SIC code 2911), 

special warehousing and storage, not elsewhere classified (SIC code 4226), crude petroleum 

pipelines (SIC code 4612), refined petroleum pipelines (SIC code 4613), chemical and allied 

products, not elsewhere classified (SIC code 5169), petroleum bulk stations and terminals (SIC 

code 5171), and automotive dealers and gasoline service stations (SIC code 5541). 

At the time of adoption, staff estimated that 800 floating roof tanks, 213 fixed roof tanks and 

33,600 underground storage tanks (UST) located at petroleum refineries and terminals, chemical 

plants and gasoline stations would be subject to the rule. Based on each tank being degassed 

once every ten years, an estimated 0.4 tons per day were expected to be controlled from floating 

and fixed roof tanks and another 0.3 tons per day were to be controlled from USTs. 

The premise of the rule has been a differential equation describing the change in concentration: 

dC/dt + QC/V = 0 

where dC/dt is the change in concentration in the tank over time, Q is the flow rate, C is the final 

concentration and V is the volume. 

The solution to the equation: 

C = Co e-(Qt/V)

when the final concentration is 10 percent of the initial concentration, or C = 0.1Co, gives: 

0.1Co = Co e-(Qt/V) 

or 0.1 = e-(Qt/V) 

Thus theoretically, to get a 90 percent reduction in emissions, then t = 2.3V/Q. Or in other 

words, if a tank were to be degassed to a control device for a period of time equal to 2.3 volume 

turnovers, 90 percent of the emissions would be controlled. The use of the equation makes a key 

assumption which is that the storage tank has no product or sludge remaining in the tank when 

the degassing begins. 

In 1995 the rule was amended to remove ambiguities in rule language relating to business and 

regulatory practices. Specifically, the clarifications included alteration of notification procedures 

and confirming that USTs to be degassed must be controlled and done in a timely period even if 

it is removed from the ground. It also intended to extend the application of the rule to storage 

tanks that were undergoing product changes by adding the term “cleaning” to the applicability of 

the rule. 

The staff report in 1995 also noted that the number of USTs degassed was significantly lower 

then estimated in 1987. Despite only 30 percent of the original estimated USTs being degassed 

annually, the report concludes that the corresponding total emission reductions from the rule 

would not change significantly. This was explained by demonstrating that more than twice the 

emissions predicted in 1987 were being controlled by venting emissions from product and sludge 

removal, rinsing and degassing instead of degassing alone. While only applied to USTs, this 

approach is noteworthy because it deviates away from the theoretical calculations that the 

original emission inventory was derived from. A similar approach will be used in this report to 

determine the emission inventory and potential emission reductions. 
Final Staff Report ________________________________

Proposed Amended Rule 1149 3 April 2008

AQMD Rules 463 – Storage of Organic Liquids and Rule 1178 - Further Reductions of VOC 

Emissions from Storage Tanks at Petroleum Facilities are closely related to this regulation. In 

particular, Rule 463 specifies emptying and refilling procedures that occur just before and after 

degassing operations. Additionally, Rule 463 (d)(2) requires the roof to float on liquid except 

when the tank is being completely emptied for cleaning or repair. While there is no definition 

for cleaning in Rule 463, it is current AQMD policy to apply the definition of cleaning in Rule 

1149 for interpretation purposes. Under Rule 1149 “cleaning” is defined as the process of 

washing or rinsing a stationary tank, reservoir, or other container or removing vapor, sludge, or 

rinsing liquid from a stationary tank, reservoir or other container. Thus the roof must float on 

liquid unless the tank is cleaned by completely draining the liquid and removing the VOC 

vapors. For example, while a tank was being drained of product, Rule 463 would apply and 

require the draining to be continuous. Once draining was complete and the roof landed, the VOC 

vapors would be removed per the requirements of Rule 1149. Once product was reintroduced 

into the tank, Rule 463 would once again apply. 

While there are no vapor concentration limits directly associated with emptying or refilling, Rule 

463 does have a vapor leak limit of 1,000 ppmv, measured as methane. Rule 1178 applies to 

larger storage tanks at petroleum facilities and establishes additional control requirements and 

specifications to those included in Rule 463. Rule 1178 applies to tanks with a True Vapor 

Pressure (TVP) of 5 mm Hg (0.1 psi). 

The Office of Pipeline Safety is the primary federal agency regulating pipelines. There are 

provisions for maintaining pipelines and reporting and repairing leaks, but no provisions for 

controlling vapors from leaks or degassing operations. In California, the Office of the State Fire 

Marshall, Pipeline Safety Division regulates the safety of hazardous liquid transportation 

pipelines. The office inspects, tests and investigates to ensure compliance with state and federal 

pipeline safety laws. Like the federal government, the state has provisions for maintaining 

pipelines and reporting and repairing leaks, but no provisions for controlling vapors from leaks 

or degassing operations. 

OPERATIONAL BACKGROUND

Vapors are created whenever there is a space between the liquid level and the roof of a storage 

tank. The more volatile (higher vapor pressure) the liquid, the more vapors are present. Large 

tanks with liquids like crude oil or gasoline can generate thousands of pounds of VOC vapors. 

These vapors will be emitted if the tank is opened to atmosphere for maintenance, repairs or 

removal. Vapors can also be emitted while the roof of a floating roof tank is allowed to rest on 

its support legs during a product change. All these types of operations are subject to the 

provisions of Rule 1149. The vapors will also be emitted when the tank is refilled and the vapor 

space is eliminated. Emissions generated from tank filling operations are covered under Rules 

463 - Organic Liquid Storage and 1178 – Further Reductions of VOC Emissions from Storage 

Tanks at Petroleum Facilities. 

Facilities limit emissions from repairs, maintenance activities, product changes and during 

refilling by controlling degassing operations. A product change occurs when a tank is used to 

temporarily store a product such as crude oil or gasoline. When the product is purchased, the 

entire tank is pumped to the purchaser. That leaves the tank empty, but filled with vapors and 

the roof resting upon the support legs. The tank seals may lose effectiveness while the roof rests 

upon the support legs leading to fugitive emissions. Some tanks can maintain the tanks in a 

“vapor tight” condition with minimal leakage even while the tank rests upon its legs. However, 

the vapors remain and must be controlled when the tank is filled and the vapors are displaced. 
Final Staff Report ________________________________

Proposed Amended Rule 1149 4 April 2008

The degassing process consists of several procedures intended to leave the tank free of product, 

sludge and vapors. The bulk of the product in the tank, if any, is pumped into another tank. A 

vacuum truck then sucks out the residual product. At this point the tank is empty of liquid but 

may contain a relatively small amount of residual liquid, some sludge and is filled with vapors. 

Depending on the amount of sludge, the tank may be cleaned and rinsed before degassing 

(purging the gas) begins. Purging the gas is generally done by sucking the vapors out of the 

tank. Because of the provisions in Rule 1149, the vapors purged are vented to a control device or 

vapor recovery system. These control devices are typically portable engines or thermal oxidizers 

that combust the vapors as fuel. Because the vapor concentration may fluctuate substantially 

during the process, propane is used as a supplemental fuel to ensure that enough fuel is available 

to maintain combustion at all times. 

Other techniques used to control vapors from storage tanks include liquid balancing and water or 

chemical washing or rinsing. Liquid balancing consists of draining the tank until just prior to the 

floating roof resting on its support legs. The tank is then filled with a low vapor pressure liquid, 

allowing the chemicals to mix, and repeating until the desired vapor pressure of the liquid blend 

is reached. Because there is no vapor space created during the mixing process, no vapors are 

created. When the tank is finally completely drained, only vapors from the low vapor pressure 

liquid created remain in the storage tank. 

Water or chemical washing or rinsing cleans the tank of product and residual sludge thus 

diminishing the amount of VOC vapor concentration in the tank. The storage tank remains 

closed or air tight during the cleaning process. Water or a chemical is added to the tanks, 

sometimes with a high pressure jet. The sludge created is pumped out and, at a minimum, 

further emissions from sludge and product residual will be minimized. Once the tank has been 

degassed, the tank will be opened to ventilate the remaining vapors. This ventilation can be done 

by opening a vent and pulling fresh air into the tank or using a blower to force the vapors out of 

the tank. There may be a final cleaning and rinsing step to remove any last remnants of sludge. 

Some facilities control fugitive emissions from vacuum trucks by routing the exhaust from the 

truck back into the tank being degassed or to a carbon adsorber. Vapors may also be minimized 

by utilizing positive displacement, submersible or diaphragm pumps. While these pumps may 

not transfer the liquid and sludge as quickly as a vacuum truck, they minimize the agitation of 

the liquid and sludge which leads to increased vapors. 

If the tank is taken out of service for maintenance, repair or removal, California Code of 

Regulations Title 8 Section 5157 prohibits entry into a hazardous atmosphere which includes 

flammable gas, vapor or mist in excess of 10 percent of its lower explosive limit (LEL). A 

significant number of tanks degassed continue venting vapors to the control device until the 10 

percent LEL is met. It should be pointed out that as currently written, a company can comply 

with Rule 1149 by purging the vapors to a control device for a time equal to 2.3 air exchanges 

and then releasing the remaining vapors even though product, sludge and/or a hazardous 

atmosphere remains in the tank. 

Storage tank operators minimize the amount of vapors created by utilizing floating roof tanks. 

These types of tanks have a roof that floats on top of the liquid product. Unlike fixed roof tanks 

where the roof remains on the top of the structure (see Figure 1), the floating roof level 

correspondingly changes with the level of the liquid to prevent any space being created between 

the liquid level and the roof (see Figure 2). The roof can remain floating on the liquid from the 

total capacity of the tank all the way down to about six feet from the bottom of the tank for most 
Final Staff Report ________________________________

Proposed Amended Rule 1149 5 April 2008

tanks and down to one foot for drain-dry breakout tanks. At that point the floating roof rests on 

its support legs and vapor space is created. When on the support legs, the vapor space is only 

about one tenth the volume of a fixed roof tank with the same capacity because the vapor space 

is about six feet while tank height is closer to sixty feet. A typical practice is to store more 

volatile liquids in floating roof tanks while heavy liquids to be stored for longer periods would 

more likely be sent to a fixed roof tank. 

 

Figure 1 – Fixed Roof Tank (From AP-42, Section 7.1, U.S. EPA 
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Proposed Amended Rule 1149 6 April 2008

Figure 2 – Floating Roof Tank (From AP-42, Section 7.1, U.S. EPA) 
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Proposed Amended Rule 1149 7 April 2008

Pipeline degassing is conducted in a similar manner to degassing a fixed roof tank with two 

noteworthy differences. First, the pipeline can be sealed at each end so as to minimize the vapor 

space opened to only the particular section being tested, maintained or replaced. These vapors 

can easily be captured and controlled under normal circumstances. Second, an inert gas, such as 

nitrogen, is often introduced at very high pressure to keep product and flammable vapors away 

from the work area. As the pipeline is refilled with product, the high pressure inert gas must be 

released. At the interface between inert gas and product there is some small amount of vapor 

mixing that potentially could emit a small amount of VOC. However, trying to control the small 

amount of VOC would require capture and control of a high pressure gas creating an unsafe 

condition.

PROPOSED AMENDMENTS

Staff proposes to amend Rule 1149 as follows: 

• Remove time and equipment requirements in paragraphs (c)(5) and (c)(6) and replace 

them with a vapor concentration requirement of 5,000 ppmv, using EPA Reference Test 

Method 21 – Determination of Volatile Organic Compound Leaks, measured as methane. 

The concentration must be met for at least one hour after degassing has been completed. 

This will prevent tanks with excess product residual or sludge from being opened 

prematurely. The proposed vapor concentration standard conservatively translates to a 

ten percent LEL already met by many degassing operations. The vapor concentration 

standard will capture the majority of emissions created by product residual and sludge. 

Any technique, including liquid displacement, is allowed as long as any vapor displaced 

is routed to an approved vapor control or recovery system and the vapor concentration 

standard is met. In most instances, companies will utilize the same techniques currently 

in use but be required to do so for a longer period of time. However, new innovations 

and processes may be developed to meet the proposed standard. By establishing a 

standard as opposed to one or more control techniques, the rule provides flexibility to 

industry to apply technological advances.

• Extend the applicability of the rule to pipeline and to more above ground storage tanks 

(see Table 1). The proposed volume for gasoline storage tanks is to make the 

requirements for above ground and underground tanks consistent. The limit for crude oil 

storage tanks will capture most stationary tanks but not smaller portable tanks. 

Degassing storage tanks with low vapor pressure products was previously unregulated 

and the proposed rule will now require large tanks to control those emissions. 

Table 1 – Proposed Changes to Storage Tank Applicability 

Vapor 

Pressure 

Typical 

Products 

Current 

(gallons) 

Proposed 

(gallons) 

3.9 psia RVP Gasoline 19,815 500 

2.6 psia RVP Crude 39,630 26,420 

0.5 psia RVP Kerosene N/A 100,000 

• Lower the VOC vapor concentration of a Vapor Leak from 10,000 ppmv to 5,000 ppmv. 

This will make the Vapor Leak standard consistent with the vapor concentration standard. 

It will require all the hoses, fittings and connections to meet the same standard the tank or 
Final Staff Report ________________________________

Proposed Amended Rule 1149 8 April 2008

pipeline is required to meet. It differs from the requirements of “Vapor Tight” in Rule 

463 (1,000 ppmv) and Rule 1178 (500 ppmv) because product and residual is being 

removed from the tank or pipeline instead of “stored” to which Rule 463 applies. The 

proposed amendment will also remove the test method from the definition and place it in 

the Test Methods section. The test method will include directions for distance and/or 

placement of the probe inlet. For storage tanks, the probe inlet shall be one foot above 

the bottom or sludge. Cylindrical tanks must be monitored at least two feet from the 

inner surface of the wall. Pipelines shall be monitored one foot or more from the 

pipeline. All monitoring measurements are to be recording and maintained to verify 

compliance with the vapor concentration standards. 

• Require floating roofs that have landed on their legs or supports to be free of vapors, 

vented to a control device or, as an additional compliance option for drain-dry breakout 

tanks, be maintained in a vapor tight condition of 500 ppmv measured as methane. A 

compliance schedule is included for drain-dry breakout tanks that must be modified to 

meet the compliance option. Monitoring will be required monthly and records of 

monitoring results shall be maintained to verify compliance. While the roof rests on its 

support legs, the seals may lose effectiveness and fugitive emissions may occur. Roof 

landings may occur during product changes when crude oil is received from overseas and 

when products are sold from one company to another. This will address a common 

situation and codifies an enforcement policy. Definitions for “Drain-Dry Breakout Tank” 

and “Vapor Tight Condition” will be included. 

• Require vacuum trucks that remove product residual and sludge from pipeline and 

storage tanks subject to the rule to exhaust vapors into a control device. Vacuum trucks 

are not designed to store vapors or control vapors themselves. When vacuum trucks 

pump product into their tanks, vapors are created from the liquid and sludge being 

agitated and may escape to atmosphere if not properly controlled. 

• Limit the exhaust concentration of control devices used to 500 ppmv, measured as 

methane. In many cases the vapor concentration in a tank can be greater than 100,000 

ppmv. Ninety percent control would allow 10,000 ppmv to escape and even 99 percent 

control would allow 1,000 ppmv to escape. This will set a stringent, yet achievable 

standard that is consistent with other AQMD rules. 

• Require that product residual and sludge taken from pipeline and storage tanks subject to 

the rule are stored or disposed into closed containers or control systems free of liquid and 

vapor leaks. This will reduce emissions that might occur while the waste material is 

waiting further processing. Prior to the completion of degassing operations, all waste 

shall be disposed or stored in closed containers or control systems. An exception will be 

included for draining liquid from pipeline as long as the draining is continuous and the 

liquid is immediately transferred into a closed container. This will accommodate field 

repair of pipelines where draining into closed containers may lead to spillage and soil 

contamination. Once degassing has been completed per the proposed amendments, any 

remaining sludge should be mostly VOC free and can be transferred into storage bins or 

other appropriate waste containers. However, vacuum trucks used to collect liquid and/or 

sludge from tanks and pipelines subject to this rule must continue to limit their exhaust to 

500 ppmv, measured as methane. 

• Eliminate the emergency notification requirements and shorten the notification period 

and duration as well as eliminating the need for authorization. The notification procedure 

will be streamlined requiring between two hours and two days notification before 
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Proposed Amended Rule 1149 9 April 2008

degassing takes place. It is common currently to have several duplicate notifications for 

a single degassing event due to scheduling issues. In addition, emergency degassing 

operations are delayed while waiting for the emergency to be approved by an authorized 

agency officer allowing uncontrolled VOC emissions into the atmosphere. Most 

emergency situations will take longer than two hours to get degassing equipment on-site. 

In the rare instance where an emergency occurs and degassing equipment is available in 

less than two hours, the facility may utilize Rule 430 – Breakdown Provisions. The new 

notification procedures will allow more flexibility to affected sources and improve the 

accuracy of the notifications. 

• Delete the definition for Underground Storage Tank. The limits for underground were 

previously different and thus necessitated defining the difference between above ground 

and underground tanks. The limits are now the same and differentiation is no longer 

necessary. 

• Add a definition for Natural Gas and exempt natural gas pipelines from the provisions of 

the rule. Natural gas is comprised mostly of methane which is not considered a VOC. 

• Include a quantification protocol for voluntary greenhouse gas reductions. The provision 

in PAR 1149 is voluntary and limited to the control of methane emissions from the 

degassing of natural gas pipelines, which is currently exempt from the requirements of 

the rule. Efforts to limit methane emissions from natural gas pipeline repair and 

maintenance activities will allow companies to reduce Greenhouse gas emissions. The 

quantification protocol calculation methodology standardizes the quantification of the 

reductions but is general enough to allow innovative techniques as they are developed. 

• Add a definition for Reid Vapor Pressure. 

• Revise the definition of Volatile Organic Compound to refer to Rule 102 to be consistent 

with other VOC rules. 

• Exempt small diameter pipelines and small lengths of pipeline depending on the vapor 

pressure of the liquid it previously contained. The pipeline exemptions are based on the 

exemptions for storage tanks with similar volumes. Thus a 500 gallon gasoline storage 

tank is roughly equivalent to a 100 foot length of pipeline containing gasoline. Similarly, 

0.25 miles of crude pipeline is roughly equivalent to a 26,420 gallon crude oil storage 

tank. 

• Remove the exemption for storage tanks exempted in Health and Safety Code Section 

25281. Most of the tanks exempted under Health and Safety Code Section 25281 will not 

be subject to the amendments because they contain low vapor pressure products. 

However, gasoline tanks on farms with capacities greater than 500 gallons will now be 

subject to this rule. Gasoline tanks on farms with capacities greater than 1,100 gallons 

were already subject to the rule. 

• Include an exemption from the requirements of the rule when tanks and pipelines are 

opened to connect or disconnect degassing equipment, sample emissions, purging inert 

gas from pipelines when reintroducing product or to connect or disconnect the pipeline 

including associated control techniques or control equipment. Based on technological 

and physical limitations and practical in situ repair operations, it has been AQMD policy 

not to check for vapor leaks when equipment or activities are being put in place that will 

minimize emissions as long as the work is continuous. In the case of pipelines, the only 

access will likely be the opening directly where the pipeline is disconnected. During the 
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Proposed Amended Rule 1149 10 April 2008

process of opening the pipeline, the operation will be exempt. However, once the 

pipeline is open, measures must be taken to limit vapor emissions. Such measures may 

include, but are not limited to, blinding the pipeline, blocking with mud plugs or putting 

dry ice in the pipeline. Once the repair or maintenance activity is concluded, the vapor 

control measure may need to be removed to allow product flow. During the removal of 

the vapor control measure and subsequent reconnection of the pipeline, the rule will not 

apply. 

EMISSION INVENTORY

The original emission inventory generated in 1987 estimated that uncontrolled emissions subject 

to Rule 1149 were 1.26 tons per day. Above ground storage tanks (AST) accounted for 0.5 tons 

per day while USTs accounted for the remainder. Based on the theoretical reduction from 

degassing over 2.3 air exchanges, the rule was expected to reduce emissions by 0.7 tons of VOC 

per day, with 0.4 tons of VOC per day being reduced from ASTs. The 1995 rule amendment 

made some new assumptions regarding how to calculate UST emissions but did not change the 

uncontrolled or expected reduction emission inventories. 

However, over the 18 years since the initial emission inventory was generated, tank types, 

capacities and frequency of degassing incidents have changed. Initially, all tanks were assumed 

to be degassed once every ten years and estimates were made to calculate the volume required to 

be degassed. The initial emission inventory was based on floating roof tanks having 56,991 

cubic feet to be degassed. The average fixed-roof tank degassed had a volume of 125,214 cubic 

feet to degas. Staff estimated that 101 tanks would be degassed each year (80 floating and 21 

fixed). Assuming complete saturation of gasoline or crude oil, this accumulates to 0.5 tons of 

VOC per day. 

Notification provisions in the rule have provided AQMD with detailed information including 

location, tank capacity and tank contents. Except in the relatively uncommon situation where a 

tank is degassed using liquid displacement, each time a tank is to be degassed by the facility or 

by a third party contractor, the degasser will notify the AQMD. With this information, staff has 

been able to refine the estimates of the volume, contents degassed and frequency of degassing 

events. Most importantly, the notification data shows that the ASTs are degassed at more than 

three times the frequency predicted. While most ASTs still are degassed every ten years or so 

for periodic repair and maintenance activities, some ASTs are degassed on a weekly basis 

because they are used primarily for product changes. 

A limitation, however, is the lack of information regarding whether the AST was a floating roof 

or fixed roof type. This is important because for equal capacity tanks, the volume degassed in a 

floating roof tank is approximately one tenth that of a fixed roof tank. For example, a typical 

tank height is approximately 60 feet. It would be necessary to degas the entire 60 feet of a fixed 

roof tank while a floating roof tank would only need to degas about six feet of space. Staff 

conducted an assessment to determine the frequency of degassing when comparing floating 

versus fixed roof tanks. Industry was consulted, staff made site visits and compared notifications 

with tank rosters. It is estimated that 90 percent of all AST degassing operations are for floating 

roof tanks. Table 2 summarizes the notification data submitted to the AQMD between 2004 and 

2006. 
Final Staff Report ________________________________

Proposed Amended Rule 1149 11 April 2008

Table 2 – Notification Data Summary 

Above Ground Storage Tanks 2004 2005 2006 3 yr ave. 

# AST degassed 295 268 421 328 

Ave capacity AST (cubic feet) 765,335 732,731 720,202 739,422 

Total volume degassed (million cubic feet) 44.7 38.9 60.0 47.9 

Total uncontrolled emissions (tpd) 1.7 1.4 3.1 2.1 

 

The summary data shows that an average of 328 ASTs with an average capacity of 739,422 

cubic feet were degassed annually. The volume was calculated by using the volume reported and 

assuming that only ten percent of the tanks were fixed and would degas the entire volume. For 

the remaining 90 percent of the ASTs, only about one-tenth of the volume reported would 

require degassing. This is because the roof of the floating roof tanks “floats” on the liquid in the 

tank until the tank liquid level is lower than the support legs which are generally about six feet 

tall. 

Using the ideal gas law methodology, the uncontrolled average annual emission inventory 

estimate from ASTs would be 2.1 tons of VOC per day. The vapor pressure and molecular 

weight were determined from the product in the tank. The ideal gas law methodology assumes 

that complete saturation has had time to occur and that there are no additional sources of 

emissions. It is calculated as follows: 

E = ( VP / 14.7 psia) * ( MW / 379 ft3) * V 

Where 

E = emissions, lb 

VP = vapor pressure, psia 

14.7 psia is atmospheric pressure under standard conditions 

MW = molecular weight, lb/lb-mole 

379 ft3 is the standard cubic feet per lb-mole at standard conditions 

V = volume, cubic feet 

However, the actual saturation rate depends on a variety of factors including temperature, 

agitation and time. For example, a completely filled fixed roof gasoline tank quickly drained 

would have a lower saturation rate compared to the same tank that was near empty when drained. 

Another factor complicating the ideal gas law methodology is sludge and product residue 

remaining in the tank when degassing commences. Additional hydrocarbon vapors are released 

from the sludge and residue while the tank is degassed. 

In order to get a clearer picture of actual emissions being generated from tank degassing 

operations, 56 degassing logs were reviewed (see Appendix A). The logs indicate that there are 

fewer emissions in the storage tanks than the ideal gas law methodology would suggest. The 

actual emissions coming from tank degassing are 69 percent of the expected emissions using the 

ideal gas methodology. While most tanks have initial vapor concentrations greater than 100 

percent LEL (roughly 50,000 ppmv, measured as methane), this is well below complete 

saturation. A possible explanation is that the tanks are drained faster than the liquid can 

evaporate. Once drained, degassing operations take place sooner than sludge and product 

residual can saturate the vapor space. Thus where the ideal gas law methodology would expect 

complete saturation, only partial saturation is seen. There may also be some unquantifiable loss 

when the contents of the tank are being pumped out of the tank. Vapor may be inadvertently 

removed if some part of the vacuum hose is above the liquid level. 
Final Staff Report ________________________________

Proposed Amended Rule 1149 12 April 2008

Additionally, the degassing logs show that sludge and product residual significantly contribute to 

the emissions emanating from the storage tanks. A tank with partial saturation should be able to 

degas in a shorter time period than a completely saturated tank. However, the logs indicate that 

degassing actually takes a much longer time. On average, it takes two to three times longer 

because product residual and sludge continue to release vapors into the tank being degassed. 

In the example provided in Table 3, a sample degassing log is examined. A floating roof 

gasoline tank with a vapor space of 7,921 cubic feet (59,249 gallons) is to be degassed. To 

comply with the current regulation, the company must degas at least 18,218 cubic feet of 

volume. The initial inlet concentration (150 percent LEL) is well below complete saturation 

used for an ideal gas calculation (approximately 600 percent LEL). After just over two hours, 

2.3 air exchanges has been surpassed with an associated 149 pounds of VOC reduced. However, 

at least that much more remains in the tank and is not controlled until the inlet concentration is 

reduced below ten percent LEL. In the example tank, the emission reduction at 2.3 air 

exchanges is approximately 40 percent and the actual emissions are about 74 percent of the 

expected emissions. 

Table 3 - Degassing Log Example 

Gasoline Tank Example 

Volume to be Degassed: 7921 cubic feet 

Expected Emissions: 502 pounds of VOC 

Time 

Flow 

from tank 

(cfm) 

Cumulative 

Volume 

(cubic feet) 

Inlet 

Concentration 

(% LEL) 

Hourly 

emissions 

(pounds) 

Cumulative 

Emissions 

(pounds) 

1345 100 0 150 0.0 0.0 

1400 200 1500 125 5.7 5.7 

1500 700 13500 100 37.7 43.3 

1600 800 55500* 76 105.5 148.8 

1700 1000 103500 48 91.6 240.5 

1800 1000 163500 21 72.3 312.8 

1900 2100 223500 9 31.6 344.5 

2000 2100 349500 7 28.5 372.9 

*2.3 Air Exchanges Surpassed 

Expected 

2.3 Air 

Exchanges Actual 

502.0 148.8 372.9 

Closer examination of individual tank logs reveal a wide variation in the actual emissions 

degassed from the tank. Some tanks have emissions much lower than expected suggesting a tank 

relatively free of sludge and product residual that was full to begin with and drained quickly. 

Others have emissions greater than expected probably because there was a larger vapor space 

that had time to reach equilibrium and/or significant amounts of sludge and product residual that 

continued to evaporate while the tank was being degassed. Theoretically, 2.3 air exchanges 

should reduce emission by 90 percent but the logs indicate an actual reduction rate of only 37 

percent. 
Final Staff Report ________________________________

Proposed Amended Rule 1149 13 April 2008

Using the notification data information and comparing the ratios of expected versus actual and 

expected versus 2.3 air exchanges we can determine how many pounds of emission can be 

captured by adopting a vapor concentration standard and comparing it to amount of emissions 

captured by the current standard of 2.3 air exchanges (see Table 4). 

Table 4 – Emission Inventory Comparison 

Uncontrolled 

2.3 Air 

Turnovers Remaining 

Total emissions using ideal gas law (tpd) 2.1 1.9 0.2 

Total emissions from degassing logs (tpd) 1.42 0.5 0.92 

Comparing the two methods to calculate emission inventory shows that the there is a smaller 

overall inventory using emissions from degassing logs. However, more emissions reductions can 

be realized by further enhancements to the rule, particularly by the establishment of a vapor 

concentration standard. 

In addition to the already regulated ASTs and USTs, the proposed rule amendment would lower 

the tank capacity and vapor pressures subject to the regulation. ASTs of capacities of 500 

gallons or greater containing gasoline would be subject to the rule. The 100,000 liter (26,420 

gallon) tanks or greater containing crude oil or other products with a Reid vapor pressure greater 

than 134 mm Hg (2.6 psi) and any tank larger than 378,500 liters (100,000 gallons) containing a 

product with a Reid vapor pressure greater than 5 mm Hg (0.1 psia) would be subject to Rule 

1149. 

Survey data and tank rosters provided by major refiners indicate that approximately 470 new 

tanks would be subject to the rule. The average capacity of the newly applicable tanks reported 

by the refiners is 2.5 million gallons. The average of the newly applicable tanks at terminals and 

other locations is 2.2 million gallons. The overall average for newly applicable tanks is 2.3 

million gallons. The proposed amendments will regulate an additional 50 percent of VOC 

containing tank volume in the AQMD resulting in commensurate reduction of VOCs emitted to 

the atmosphere. 

Using the actual tank capacities and product contents from those refiners who provided the 

survey data, the average uncontrolled degassing emission from a newly applicable tank is 2,370 

pounds of VOC. Applying the same correction factor of actual versus expected emissions 

(0.685) seen from the degassing logs summarized in Table 3, there would be 1,620 pounds of 

uncontrolled emission from degassing each newly applicable tank. Conservatively assuming that 

the tanks are degassed once every ten years, the annual uncontrolled emissions from newly 

applicable tanks would be 76,140 pounds (0.1 tons per day). 

Aside from storage tanks, pipelines containing organic liquids, primarily crude oil and gasoline, 

would also be subject to PAR 1149. According to the California Office of the State Fire 

Marshall, there are 7,500 miles (approximately 4,000 miles in the South Coast Air Basin) of 

hazardous liquid transportation pipeline within the state. California laws mandate that each 

pipeline system be tested at least every five years. Testing usually consists of hydrotesting or 

use of internal inspection tools sometimes known as “smart pigs”. Most pipeline inspection and 

repair activities already vent vapors to an uncontrolled vacuum truck. The result is 4.2 million 

cubic feet annually of gasoline or crude oil vapor could be released to the atmosphere. The 

proposed amended rule would apply to pipelines outside of permitted facilities that were six 
Final Staff Report ________________________________

Proposed Amended Rule 1149 14 April 2008

inches or greater in diameter. Pipelines shorter than 100 feet in length are exempt as are 

pipelines shorter than 0.25 miles containing or previously containing VOC liquids having a Reid 

vapor pressure less than 202 mm Hg. Staff estimates the addition of pipelines to PAR 1149 adds 

0.4 tons of uncontrolled VOC per day to the emission inventory. 

In the 1987 version of the rule underground storage tanks (USTs) originally contributed 0.63 

tons per day to the uncontrolled emission inventory and the rule was expected to reduce 0.3 tons 

of VOC per day. In 1995, the staff report indicated that the number of USTs had decreased by 

70 percent. However, emission calculations in the 1995 Final Staff Report for Proposed 

Amended Rule 1149 – Storage Tank Degassing show that the emission reductions remained the 

same because emissions from USTs were higher than originally estimated and industry practices 

now reduced emissions by 99 percent. Over the past three years, an average of 501 USTs were 

degassed with an average capacity of 11,346 gallons. The uncontrolled emissions from USTs 

were 0.07 tons per day calculated by adjusting the number of tanks and average volume in 

comparison to estimates made in previous staff reports. Using the 99 percent control efficiency 

claimed by the 1995 rule amendment, the emission reduction from USTs were also 0.07 tons of 

VOC per day. No emission reductions from USTs are claimed in this proposed amendment. In 

summary, the total uncontrolled emissions from all sources subject to the proposed amendments 

to Rule 1149 is 1.99 tons of VOC per day with 0.57 tons of VOC per day controlled by existing 

regulations (see Table 5). Therefore the remaining emission inventory to be further regulated by 

the proposed amendments to Rule 1149 is 1.42 tons per day of VOC. 

Table 5 – Emission Inventory from All Rule 1149 Sources 

Source 

Emissions 

Inventory 

Before 

Control 

Emissions 

Controlled 

by Existing 

Rule 1149 

Remaining 

Emissions 

Inventory 

ASTs currently subject to rule (tpd) 1.42 0.5 0.92 

USTs (tpd) 0.07 0.07 0 

Newly applicable ASTs (tpd) 0.1 0 0.1 

Pipelines (tpd) 0.4 0 0.4 

Total emissions from all Rule 1149 

Sources (tpd) 1.99 0.57 1.42 

EMISSION REDUCTIONS

The proposed rule amendment would set a vapor concentration limit of 5,000 ppmv on tanks and 

pipelines subject to the rule. Connections, hoses, and vacuum trucks would also be required to 

keep emissions below 5,000 ppmv. Control devices would not be required by the regulation. 

Alternative methods such as routing the exhaust to other tanks, applying chemicals or water to 

reduce vapors or any other means to reduce the tank or pipeline concentration would be allowed 

so long as hydrocarbon vapors with a concentration greater than 5,000 ppmv were not allowed to 

be vented to atmosphere. Control devices used to reduce the vapors in tanks and pipelines would 

be limited to an exhaust concentration of 500 ppmv, which is consistent with other AQMD rules. 

A limit of 5,000 ppmv captures an estimated 90 percent or more of the remaining emissions. 

Utilizing the degassing logs, a comparison can be made between the quantity of emission 

captured when the 5,000 ppmv standard is reached and the total quantity of emissions in the 
Final Staff Report ________________________________

Proposed Amended Rule 1149 15 April 2008

storage tank. Reviewing the example in Table 3, almost 97 percent of emissions are captured 

when degassing to 5,000 ppmv (roughly ten percent LEL). Reviewing all of the storage tanks 

that met or exceeded the standard, a limit of 5,000 ppmv captures between 86.3 percent and 99.7 

percent of emissions from tanks. The average emission reduction is 95.8 percent. 

Adoption of a vapor concentration standard of 5,000 ppmv will reduce emissions from existing 

and newly applicable sources by at least 90 percent. The total annual uncontrolled VOC 

emissions from existing and newly applicable sources are 1.99 tons per day. The current 

provisions in the rule already reduce 0.57 tons per day of the uncontrolled VOC emissions. The 

proposed rule amendments will reduce VOC emissions by another 1.27 tons per day calculated 

based on the practice of degassing to 5,000 ppmv (see Table 6). If the tanks were near complete 

saturation, the inventory would increase to 2.1 tons per day and another 0.7 tons per day of 

emission reductions would be realized. Further controlling vacuum trucks used to remove 

residual product and sludge, requiring residual product and sludge to held in closed containers 

that are free of liquid and vapor leaks and establishing a vapor concentration requirement for 

control devices will limit fugitive emission losses. 

Table 6 – Emission Reductions from All Rule 1149 Sources 

Source 

Emission 

Inventory 

Emissions 

Controlled 

by Existing 

Rule 1149 

Remaining 

Emissions 

Inventory 

Emissions 

Controlled 

by 

Proposed 

Rule 

ASTs currently subject to rule (tpd) 1.42 0.5 0.92 0.82 

USTs (tpd) 0.07 0.07 0 0 

Newly applicable ASTs (tpd) 0.1 0 0.1 0.09 

Pipelines (tpd) 0.4 0 0.4 0.36 

Total emissions from all Rule 1149 

sources (tpd) 1.99 0.57 1.42 1.27 

Along with reductions in VOC emissions from the proposed provisions of this rule, there would 

also be some increases in criteria pollutants because of increased use of control equipment. 

Except where liquid balancing is used, the primary methods of control are absorption onto 

carbon or oxidation using internal combustion engines and thermal oxidizers. Conservatively, it 

is assumed that all new sources will be controlled using either an internal combustion engine or 

thermal oxidizer. Undoubtedly, some sources will use liquid balancing and other technologies or 

degassing methods may be developed which do not require combustion. 

Over the past three years, 47.9 million cubic feet of tank space was degassed on average 

annually. Based on this average and the calculated average cubic feet degassed per gallon of 

propane, 35,143 gallons of propane are used to degas storage tanks each year. PAR 1149 would 

increase the usage of propane by nearly seven times for tanks already subject to the rule. 

Additionally, another 7.0 million cubic feet of degassing would be necessary with the proposed 

pipeline and smaller/low vapor pressure tank requirements. The total average amount of 

degassing would increase to 54.9 million cubic feet annually. The total propane from degassing 

operations would increase to 277,273 gallons annually. Another 26,700 gallons of propane 

would be required to control vapors from storage tank roof landings. The overall total propane 

increase would be 303,973 gallons annually. 
Final Staff Report ________________________________

Proposed Amended Rule 1149 16 April 2008

AQMD default emission factors were used for criteria pollutants emitted by thermal oxidizers 

and internal combustion engines except for NOx, VOC and CO from internal combustion 

engines. NOx, VOC and CO emission factors for internal combustion engines were taken from a 

source test conducted on an internal combustion engine fired with propane controlling vapors 

from a tank degassing operation. Like other internal combustion engines used for this purpose, it 

is equipped with a catalytic converter. U.S. Department of Energy, Energy Information 

Administration factors were used to determine carbon dioxide (CO2) emission factors. The ratio 

of thermal oxidizer use (69 percent) to internal combustion engine use (31 percent) was 

determined from notification data. The average daily increase in criteria pollutants and 

greenhouse gas emissions are calculated below: 

Table 7 – Related Increase in Criteria Pollutants and Greenhouse Gas Emissions 

Current 

NOx 

(annual 

lbs) 

VOC 

(annual 

lbs) 

SOx 

(annual 

lbs) 

CO 

(annual 

lbs) 

CO2 

(annual 

lbs) 

Methane 

(annual 

lbs) 

PM 

(annual 

lbs) 

at 100% thermal oxidizer use 450 9 162 112 445,227 10 10 

at 100% IC engine use 1,230 64 12 738 445,227 0 176 

at 69%/31% T.O./ICE use 690 26 116 305 445,227 7 61 

Proposed 

NOx 

(annual 

lbs) 

VOC 

(annual 

lbs) 

SOx 

(annual 

lbs) 

CO 

(annual 

lbs) 

CO2 

(annual 

lbs) 

Methane 

(annual 

lbs) 

PM 

(annual 

lbs) 

at 100% thermal oxidizer use 3,891 65 1,145 797 3,155,748 70 70 

at 100% IC engine use 8,719 516 88 5,231 3,155,748 0 1,245 

at 69%/31% T.O./ICE use 4,891 204 820 2,162 3,155,748 48 432 

NOx VOC SOx CO CO2 Methane PM 

Average daily increase 

(pounds) 12 1 2 5 7,426 0 1 

For CEQA purposes, a peak emissions scenario was developed based on the busiest day over the 

past four years of notification data. On that day, two large gasoline and three large crude oil 

ASTs were degassed. One newly applicable large heavy product tank and two newly applicable 

lengths of pipeline were added. Using the same criteria emission factors in the average daily 

increase, the peak emissions, not including the associated increase in truck fuel usage are as 

follows: 

NOx VOC SOx CO CO2 Methane PM 

Peak daily increase 

(pounds) 17 1 3 9 11,178 0 2 

 

COST AND COST-EFFECTIVENESS

Currently, nearly all USTs and some ASTs are already degassed to meet the 5,000 ppmv limit. 

For those operations that currently meet only the 2.3 air exchange standard, it is calculated that it 

will take 2.8 times longer to degas a tank to the proposed limit (see Appendix B). 

For already applicable ASTs, degassing companies generally charge between $2,000 and 

$20,000 to degas tanks. For an average sized tank, a typical cost would be between $7,000 and 

$10,000 with $2,000 of that amount a flat fee and the remainder based on an hourly rate. On 

average, a typical storage tank takes about eight hours to degas to the current rule requirement of 
Final Staff Report ________________________________

Proposed Amended Rule 1149 17 April 2008

2.3 air exchanges. To reach the proposed concentration limit, it is estimated that it will take 24.1 

hours. This hourly increase of 180 percent would add $14,680 per operation. Historically, 328 

ASTs are degassed annually; therefore the cost increase would be $4.8 million dollars. 

On average, up to 192 already applicable storage tanks per year would require additional controls 

to limit vapors being exhausted by vacuum trucks while removing sludge from the tanks. At an 

estimated cost of $2,000 per operation, an additional $0.4 million dollars would be necessary to 

control vapors exhausted by vacuum trucks during sludge cleaning. Sludge cleaning occurs does 

not occur during all storage tank degassing operations. It is only necessary during repair and 

maintenance of the storage tank, not during product changes. 

At a few facilities, annualized capital expenditures totaling $37,000 for vapor pumps, system 

automation, pressure relief valves and other equipment will be necessary to meet the vapor 

control requirements during roof landings. In addition, those facilities would have a total annual 

cost of $80,100 for supplemental fuel. The total annualized cost increase for controlling tank 

landings would be $117,000. 

Already applicable ASTs

Currently: $2,000 + 8.5 hours * $941/hr = $10,000 

Proposed: $2,000 + 24.1 hours * $941/hr = $24,680 (a $14,680 increase) 

Annual Cost Increase: $14,680/operation * 328 degassing operations = $4.8 million 

Vacuum Truck Control: $2,000/operation * 192 sludge cleaning operations = $0.4 

million 

Annualized Increase for Tank Roof Landing Control: $117,000 

Total Annual Cost Increase = $4.8 million + $0.4 million + $117,000 = $5.3 million 

For the 470 newly applicable ASTs and again assuming that they are degassed once every ten 

years, 47 newly applicable tanks would be degassed. However, because the newly applicable 

tanks are 58 percent smaller, based on survey data and tank rosters, and have 51 percent lower 

vapor concentration, because of the lower vapor pressure products previously contained within, 

they could be degassed at 30 percent of the cost or $8,700. At a cost of $8,700 each, the 47 

newly applicable tanks degassed annually would do so at an annual cost of $0.4 million dollars. 

To control vapors exhausted by vacuum trucks during sludge cleaning, again at an estimated cost 

of $2,000 per operation, an additional $0.1 million dollars would be expended. 

Newly applicable ASTs

Newly applicable AST = 24.1 hours * 0.58 volume * 0.51 vapor concentration = 7.1 

hours 

Proposed: $2,000 + 7.1 hours * $941/hr = $8,700 

Annual Cost Increase: $8,700/operation * 47 operations = $0.4 million 

Vacuum Truck Control: $2,000/operation * 47 sludge cleaning operations = $0.1 million 

Total Annual Cost Increase = $0.4 million + $0.1 million = $0.5 million 

Requiring vacuum trucks to vent vapors to a control device such as a carbon canister during 

pipeline degassing would increase the cost by $500 to $4,000 per operation according to 

contractors who offer those services. An ordinary operation may potentially displace between 
Final Staff Report ________________________________

Proposed Amended Rule 1149 18 April 2008

one mile and 30 miles of pipeline depending on the distance between shut off valves. Eight 

hundred miles of pipeline need to be maintained and tested annually. At an average of five 

miles, 160 pipeline degassing operations would be necessary annually. At $2,000 per operation, 

the total annual cost increase to control pipeline degassing would be $0.3 million dollars. 

Newly applicable pipelines

Annual Cost Increase: $2,000/operation * 160 operations = $0.3 million 

For USTs, degassing companies charge between $600 and $1,000 to degas a tank. Because 

virtually all are already meeting the proposed limit, they would not need to change their 

operations or charge more to their customers. 

As proposed, the rule would further reduce emissions by between 1.27 and 1.97 tons per day if 

the VOC vapors in the storage tank are completely saturated with an estimated cost of $6.1 

million dollars. The overall cost per ton of VOC reduced by the proposed amendment would be 

$13,159 (see Table 8). 

Table 8 - Cost Effectiveness Summary 

Emission Source 

Emissions 

before 

control 

Emissions 

controlled by 

existing 

regulations 

Emissions 

controlled by 

proposed rule 

Annual 

Estimated 

Cost 

(millions) 

ASTs currently subject to 

Rule 1149 (tpd) 1.42 0.5 0.82 $5.3 

USTs (tpd) 0.07 0.07 0 $0 

Newly applicable ASTs (tpd) 0.1 0 0.09 $0.5 

Pipeline (tpd) 0.4 0 0.36 $0.3 

Total emissions from all 

Rule 1149 Sources (tpd) 1.99 0.57 1.27 $6.1 

Cost Effectiveness

Total annual cost / total annual emissions = $6.1 million / (1.27 tpd * 365 days) = $13,159 per 

ton of VOC reduced. 

INCREMENTAL COST-EFFECTIVENESS AND ANALYSES OF ALTERNATIVE 

CONTROL MEASURES

Under Health and Safety Code Section 40920.6, the AQMD is required to perform an 

incremental cost analysis when adopting a Best Available Retrofit Control Technology 

(BARCT) rule or feasible measure required by the California Clean Air Act. To perform this 

analysis, the AQMD must (1) identify one or more control options achieving the emission 

reduction objectives for the proposed rule, (2) determine the cost effectiveness for each option, 

and (3) calculate the incremental cost effectiveness for each option. To determine incremental 

costs, the AQMD must “calculate the difference in the dollar costs divided by the difference in 

the emission reduction potentials between each progressively more stringent potential control 

option as compared to the next less expensive control option.” 
Final Staff Report ________________________________

Proposed Amended Rule 1149 19 April 2008

Proposed Amended Rule 1149 implements Control Measure Fug-04 from the 2007 Air Quality 

Management Plan. Because Control Measure Fug-04 is intended to meet feasible measure 

requirements under the California Clean Air Act, an incremental cost analysis is required. 

Several alternative options were evaluated including one less stringent standard and two more 

stringent standards. The first alternative examined was to increase the number of air exchanges 

required from 2.3 as is currently required in the rule, to 4.6 air exchanges. Theoretically this 

would raise the control efficiency of the rule from 90 percent to 99 percent. However, as 

discussed above, 2.3 air exchanges only achieves 37 percent control efficiency. From review of 

the degassing logs, it is estimated that emission reductions would increase to approximately 55 

percent control efficiency. This would be well below the 90 percent control efficiency expected 

by the current proposal and reduce only 0.8 tons per day of VOC emissions. While the overall 

cost would be lower ($4.6 million), the cost effectiveness would rise to $15,753 per ton of VOC 

reduced. 

A small number of the degassing logs reviewed indicate that those tanks were degassed well 

below the proposed limit. From those logs, we can estimate that decreasing the proposed limit 

from 5,000 ppmv to 3,500 ppmv would increase the average cost of the operation by 202 percent 

and lowering the limit even further to 2,000 ppmv would increase the average cost by 221 

percent resulting in an incremental cost effectiveness of $273,973 and $684,932 per additional 

ton of VOC reduced, respectively. The large increase in incremental cost is due primarily to the 

very small additional emission reductions realized from lowering the proposed vapor 

concentration limit. 

Table 9 – Cost Effectiveness by Vapor Concentration Limit 

PPM limit 

Emission 

reductions 

(tons per day) 

Average 

Additional Hours 

Per Tank 

Annual 

Additional 

Cost (million) 

Incremental Cost 

Effectiveness 

(Cost/Additional 

Ton 

5,000 1.27 15.6 $6.1 $8,524 

3,500 1.276 17.5 $6.6 $273,973 

2,000 1.278 19.2 $7.1 $684,932 

4.6 air 

exchanges 0.8 13.0 $4.6 N/A 

VOLUNTARY GREENHOUSE GAS REDUCTION QUANTIFICATION PROTOCOL

There is an increasing need to provide a valid, regional certified reduction mechanism for global 

warming gases in the South Coast Air Basin. The AQMD Governing Board has proposed 

creation of a voluntary certified carbon-reduction program, to be called the SoCal Climate 

Solutions Exchange. This program, to be developed in the near future in a separate rule making 

activity, will incentivize cost-effective emission controls. The applicability, use, recordkeeping, 

issuance and all other aspects of the certified carbon-reduction program will be addressed when 

the SoCal Climate Solutions Exchange program is developed. 

The purpose of Rule 1149 is to reduce VOC emissions from storage tank and pipeline degassing 

operations. Methane, a VOC exempt compound, is present in natural gas pipelines. The 

proposed amended rule will include a quantification protocol for companies who voluntarily 
Final Staff Report ________________________________

Proposed Amended Rule 1149 20 April 2008

control methane emissions from natural gas pipelines. While methane is not a VOC, it is a 

global warming gas with a global warming potential more than 21 times that of CO2. 

Methane losses from natural gas pipelines mainly occur during maintenance and repairs. 

Because of the vital nature of this utility, maintenance and repairs must be accomplished as 

rapidly as possible. When a situation arises requiring the pipelines to be opened to atmosphere, 

the pipeline is closed at nearby locations on either side of the opening. The gas in the pipelines 

is allowed to blowdown or be purged from the pipeline. The repair or maintenance work is 

completed and the pipeline is reopened allowing the natural gas to flow once again. 

The most straightforward technique to minimize methane emissions is to minimize the length of 

pipeline that will be opened to atmosphere. Automated valves located several miles apart would 

be closed to isolate the area. Then manual valves located closer to the source could be closed to 

minimize the amount of blowdown gas that would otherwise be released. Other reductions 

might be possible from bleeding off the gas to a storage container or control device. If a 

combustion process is utilized, the carbon reduction would be reduced by four percent to reflect 

the subsequent release of CO2 created from burning the methane. Any supplemental fuel 

required for combustion is also subtracted from carbon reductions as it too is combusted into 

CO2. It is intended that the non-prescriptive calculation provided in PAR 1149 will provide an 

incentive to develop innovative techniques to minimize methane emissions. The global warming 

potential (GWP) for methane is taken from the International Panel on Climate Change (IPCC) 

Second Assessment Report. In the report, the IPCC established a GWP (100 years) for methane 

of 21 carbon dioxide equivalent units. 

COMMENTS AND RESPONSES

Comment 1 

The rule should consider recovering the VOC vapors to be used as fuel instead of burning low 

concentration vapors which wastes money and time and creates so much CO2. 

Response 

Staff agrees with the comment and has purposely designed the rule requirements to allow nondestructive control techniques, including liquid displacement and refrigerated condensation. 

Establishing a vapor concentration, as opposed to prescribing control techniques, provides 

flexibility to industry to apply technological advances and opt to recover vapors instead of 

combusting vapors if they deem it cost-effective. 

Comment 2 

The engine and thermal oxidizer (TO) criteria pollutant emission factors appear to be incorrect 

based on experience and past source test data. I have submitted source test data showing lower 

emission factors. Additionally, considering that voluntary emission reduction of greenhouse 

gases will become an issue sometime in the future, I think it is important to note pound for pound 

destroyed, a TO may emit as much as two to three times the amount of pollutant than the engine 

doing the exact same work. This is because the internal combustion engine uses the vapor as the 

primary fuel source while the thermal oxidizer must use a supplementary fuel to oxidize the 

extracted VOC. 
Final Staff Report ________________________________

Proposed Amended Rule 1149 21 April 2008

Response 

Staff has reviewed available source test data and adjusted the NOx and CO emission factors for 

internal combustion engines. The previous emission factors did not consider engines with 

catalytic converters which are now standard in the industry. The emission factors for CO2 were 

not altered to reflect differences in fuel usage. There is insufficient data available to try to 

quantify the amount of fuel increase attributable to internal combustion engines as compared to 

thermal oxidizers. However, supplemental fuel use will be included when determining the 

amount CO2 created when determining greenhouse gas emission reductions under subdivision 

(e) of PAR 1149. 

Comment 3 

The requirements of paragraph (c)(2) appear to mean that the vapor space of a storage tank 

should be vented to a control device once the roof lands even if the liquid in the tank has not 

completely been drained out of the tank. Please clarify. 

Response 

The requirement to control the vapor from storage tanks with the roof landed applies only after 

emptying is complete. Emptying consists of removing the bulk of the liquid but not necessarily 

the removal of residual product or sludge. Storage tanks that contain liquid, including filling 

and draining operations, are subject to the requirements of Rule 463 and Rule 1178. Rule 463 

requires the process of emptying or refilling to be continuous once the roof is resting on its legs 

or leg supports. The proposed language will be clarified accordingly. 

Comment 4 

We do not believe that PAR 1149 is a good candidate for inclusion in the proposed CO2 trading 

program, and particularly not as the very first rule. However, if Rule 1149 were ultimately 

included in the trading program, that should happen only after the trading program has been fully 

defined. Without that knowledge about the trading program, stakeholders cannot effectively 

comment on the appropriateness of including this rule. 

Response 

The recently announced SoCal Climate Solutions Exchange initiative will provide a valid, 

regional certified carbon-reduction mechanism for global warming gases in the South Coast Air 

Basin. That program will be developed as a separate regulation. PAR 1149 will include a 

quantification protocol for companies who voluntarily control methane emissions from natural 

gas pipelines to quantify carbon reductions. Natural gas pipelines will be exempt from the 

requirements of Rule 1149 because methane is not a VOC. However it is a global warming gas 

with a global warming potential more than 21 times that of CO2 and provides an opportunity to 

voluntarily reduce greenhouse gas emissions. 

Comment 5 

The AQMD suggests that the proposed 5,000 ppmv VOC concentration, which represents 

various criteria (e.g., definition of a vapor leak, degassing completion criterion, etc.), is 

approximately equal to a 10 percent LEL for gasoline. This seems like an appropriate level – it 

is consistent with the established criteria for confined-space entry, etc. We note, however, that 

compliance with the requirements of the rule would be made somewhat simpler if a combustible 

gas detector (i.e., an "LEL meter") could be used as an alternative to a "Method 21" instrument. 
Final Staff Report ________________________________

Proposed Amended Rule 1149 22 April 2008

Response 

While it is understood that many degassing operations currently use LEL meters for safety 

purposes, the limitations of the meter makes it unsuitable for enforcement purposes. The LEL 

meter must be set to the particular vapor the operator believes he is working with (i.e. hexane) 

and does not accurately detect the presence of other VOC containing chemicals. Petroleum 

products are blends of chemicals and the LEL meter may underreport the true vapor 

concentration in some cases, whereas an instrument that meets Method 21 requirements will not. 

Comment 6 

The description of the test methods in paragraph (d)(1) has been revised to include distance 

specifications for where to place the probe of an instrument when measuring VOC 

concentrations in tanks that are undergoing cleaning/degassing. (We understand that these 

distance specifications are the same as those specified in a Ventura APCD rule, and that the 

Ventura rule has a VOC criterion of 10,000 ppmv.) We believe that setting distance 

specifications is appropriate. However, because the specifications were added to the draft rule 

only recently, we have not had the opportunity to fully evaluate and discuss the implications of 

these specifications with the District. 

We would respectfully request an opportunity to more fully evaluate these proposed distance 

specifications together with staff. We believe that the final staff report should include an 

analysis that addresses, 1) the potential additional time required to degas a tank based on 

sampling at the proposed specific locations inside the tank, 2) the potential additional degassing 

time anticipated due to the District's 5000 ppmv criterion compared to the 10,000 ppmv in the 

Ventura rule, and 3) the overall feasibility of achieving the AQMD's proposed criteria. 

Response 

The distance specifications are the same as the Ventura APCD rule and commonly used field 

procedures by tank degassing operators in the AQMD. It is not uncommon for tanks degassed 

for maintenance purposes to already meet the 5,000 ppmv criterion based on monitoring 

practices that are similar to the ones proposed. The analysis to compare the additional time 

required to degas from the current standard is included in Appendix B and is more appropriate 

than comparing it to Ventura’s rule. The increased time PAR 1149 stated in Appendix B is 

included in the cost-effectiveness calculations of the rule and demonstrates the feasibility of the 

proposed criteria. 

Comment 7 

Compliance with the prohibition of vapor leaks for closed containers used to store sludge may 

warrant its own distance specification for the purpose of precluding placement of a monitoring 

probe at, or even underneath, the cover of the container. 

Response 

The distance specification for determination of vapor leaks from closed containers remains 

unchanged from the existing rule and has been in practice for many years. The distance of the 

probe shall be one centimeter or less from the source. That would allow the probe to be placed 

at the cover, but not underneath the cover of the container. 

Comment 8 

While there likely are VOC emissions associated with many pipeline repair activities, pipeline 

inspection activities typically do not result in any emissions. The process of hydrotesting a 

pipeline involves flushing the entire line with water thereby displacing product and/or vapor to a 
Final Staff Report ________________________________

Proposed Amended Rule 1149 23 April 2008

facility at the far end of the line. No venting takes place. Also, because the pipeline is filled 

with water for testing, the pipeline is no longer subject to the Rule as the "product" in the line is 

now water. With regard to the use of internal inspection tools (e.g., "smart pigs"), these tools are 

loaded into special closed "traps" and then pushed through the pipeline by the product being 

shipped. This internal inspection process also does not vent any vapors. 

Response 

The activities involving pipelines, including maintenance, repair and testing, were previously 

completely unregulated in terms of air pollution. The proposed requirements will establish 

vapor concentration limits for pipelines when they need to be opened to atmosphere. Control 

techniques such as water displacement, traps that limit vapor released during inspection and 

blinding the pipeline with inert gas or plugs are all commonly practiced acceptable methods to 

limit vapors. The proposed requirements will require that some method of limiting vapor release 

be practiced. 

Comment 9 

PAR 1149 includes streamlined notification procedures; WSPA appreciates and supports these 

revised requirements. We can reasonably expect that, for cleaning or degassing procedures 

involving tanks, the proposed revised notification requirements are not likely to be a problem. 

However, emergencies involving pipelines could be a different matter. We envision unplanned 

circumstances involving, for example, an urgent need for the services of a vacuum truck – but we 

know that not all vacuum trucks are equipped with VOC controls (e.g., carbon canisters). We 

submit that some provision for emergencies involving pipelines is warranted. 

Response 

The emergency scenario described above is best handled through the Rule 430 – Breakdown 

Provisions. Allowing the use of equipment to vent vapors without control (and likely without 

proper notification) would essentially circumvent the intent of Rule 1149. Establishing the 

guidelines for reporting an emergency, the necessary documentation to validate the emergency 

and the administrative relief the emergency situation would provide would necessitate recreating 

the provisions of Rule 430 within the framework of Rule 1149.

Comment 10 

Applicability, subdivision (a) – last sentence. This sentence is potentially confusing and can be 

misinterpreted as "pipeline outside the boundaries of a facility", "pipeline outside of a stationary 

tank", etc. We suggest that it should be re-structured to read: 

"This rule applies to the cleaning and degassing of: 1) pipeline opened to the 

atmosphere outside the boundaries of a facility; 2) stationary tank; 3) reservoir; or 

4) other container..." 

Response 

If interpreted as suggested in the comment, the rule would only apply to pipelines outside of 

facilities, pipelines outside of tanks, etc. and not to the tanks, reservoirs or other containers 

themselves. Since that is clearly not the intent of a Storage Tank and Pipeline Cleaning and 

Degassing regulation, it is not necessary to restructure the applicability. 

Comment 11 

Please consider adding a basic definition of a “pipeline”. This would be appropriate since 

pipelines are newly regulated as a specific source category under this rule. 
Final Staff Report ________________________________

Proposed Amended Rule 1149 24 April 2008

Response 

There would be no additional information provided by including a definition in the rule for 

“pipeline” that would be identical to the dictionary definition of the word.

Comment 12 

Although "liquid balancing" might not be the appropriate term, the practice of flushing a pipeline 

with low vapor pressure organic material, or with water, is common. Thus, some recognition of 

this practice in the definitions might be worthwhile. 

Response 

Recognizing the various techniques available for complying with the proposed provisions of 

requirement paragraph (c)(3) is not necessary because paragraph (c)(3) references a vapor 

standard that shall be met and does not prescribe a method to achieve that standard. Specifying 

specific control techniques may have the inadvertent effect of stifling innovation by limiting the 

techniques only to those listed. 

Comment 13 

It is not clear that the requirements under paragraph (c)(1) are intended to be applicable to 

stationary sources. WSPA suggests retaining the word "stationary" (i.e., do not delete the entire 

phrase, "Above-ground stationary tank.."). Otherwise, the section could be misconstrued as 

potentially requiring degassing of tanker trucks or other portable tanks. 

Response 

The word “stationary” will be retained. 

Comment 14 

Please see Table 1, paragraphs (c)(2), and (e)(2). PAR 1149 expresses vapor pressure criteria as 

Reid Vapor Pressure (RVP). However, Rules 463 and 1178 use True Vapor Pressure (TVP) – 

see Rule 463 (c), and Rule 1178 (b), respectively. The use of two different measurement 

"standards" in different rules applicable to tanks is potentially confusing. WSPA suggests that 

PAR 1149 also use TVP. 

Response 

Per discussion with the commenter, the request has been withdrawn and the original references 

to RVP will be retained. 

Comment 15 

One of the criteria for applicability of the rule to tanks or pipelines is that they contain or 

"previously contained" organic material having a certain vapor pressure. We understand that it is 

the AQMD's intent that this reference is to the material that was "last present" in the tank or 

pipeline before degassing – and not any material historically present. Please clarify the language 

accordingly. 

Response 

Pipelines and tanks last containing products subject to the rule must meet the requirements of 

PAR 1149. Products that were removed from tanks or pipelines and subsequently replaced with 

liquids not subject to the rule would not be subject to the provisions of PAR 1149. The term 

“previously contained” will be replaced with “last contained”. 
Final Staff Report ________________________________

Proposed Amended Rule 1149 25 April 2008

Comment 16 

Is it the AQMD's intent to require that vacuum trucks used for cleaning/degassing activities be 

equipped with exhaust controls up until the point where the criteria in paragraphs (c)(1) or (c)(4) 

(for tanks and pipelines, respectively) are achieved? We suggest that the language similar to the 

provision in paragraphs (c)(9) be added to paragraph (c)(6). Also, one common practice is to 

route the exhaust from the vacuum truck exhaust back into a storage tank. Because the vacuum 

truck is not exhausting vapors to the atmosphere, we believe that the requirements of paragraph 

(c)(5) would be met. 

Response 

Vacuum trucks used to remove liquid, sludge or vapors from tanks or pipelines subject to this 

rule must limit their exhaust emissions below 500 ppmv or control emissions in some other 

manner. Venting their exhaust vapors to a control device or into a storage tank including the 

tank being degassed would be acceptable means of controlling the vapors. However, the process 

of vacuuming VOC containing liquids and sludge can create additional fugitive vapors. 

Therefore, staff is proposing to require all operations subject to the rule utilizing a vacuum 

truck, including tank and pipeline draining, residual cleaning and sludge cleaning, to vent the 

exhaust to a control device or meet the 500 ppmv vapor concentration limit. Vendors offering 

control equipment for vacuum truck exhaust have said that they have sufficient inventory to meet 

industry’s needs. There are also alternative techniques available, including submersible, 

diaphragm and positive displacement pumps that can be used to minimize vacuum truck exhaust 

fugitive emissions. 

Comment 17 

WSPA appreciates the AQMD's efforts to streamline the notification process. However, we 

believe that the proposed written follow-up notice and fee payment, required by the next 

business day, would be exceptionally burdensome – particularly for those who conduct frequent 

product changes. Therefore, we suggest that the follow-up reports and fees be submitted on a 

monthly basis. We believe that, in addition to being less burdensome for the AQMD as well, the 

cost of check processing and handling will be reduced for both the payer and the AQMD. 

Response 

Current AQMD policy for other regulations requiring notification, including Rules 203, 1166 

and 1403 allow up to three working days after the event has taken place for follow up submittals. 

The proposed follow-up notification requirements in PAR 1149 will reflect that same policy and 

allow up to three working days. 

Comment 18 

This section requires a continuous organic vapor analyzer on the outlet of carbon adsorption 

systems used for degassing. We note that, although this language is in the current rule, the 

requirement only applies to equipment used for degassing. The proposed requirement could be 

interpreted to apply to carbon canisters on vacuum trucks. Because we do not believe that this is 

the AQMD's intent, we request that the requirement be clarified accordingly. 

Response 

The rule will be clarified to limit the applicability of the continuous organic vapor analyzer to 

carbon adsorption systems used for degassing.
Final Staff Report ________________________________

Proposed Amended Rule 1149 26 April 2008

Comment 19 

The provision of paragraph (c)(8), as written, can be interpreted to require that liquids or sludge 

removed from a tank or pipeline must be stored. However, because there can be alternate 

dispositions for liquids or sludge (e.g., draining to a closed industrial sewer system), we suggest 

that that this requirement be clarified to apply to those situations if/when liquid or sludge is 

stored. In addition, a reference to paragraph (c)(3) needs to be added for the benefit of pipelines. 

Response 

PAR 1149 will be clarified to include a reference to paragraph (c)(3). Additionally, it will allow 

disposal into closed systems such as closed industrial sewer systems or sumps, as well as storage 

containers to allow for immediate treatment and control of VOC emissions. 

Comment 20 

Requiring drain-dry breakout tanks to evacuate the vapor space each time it lands would create 

safety problems, provide little air quality benefit, greatly increase Greenhouse gas emissions and 

potentially lead to disruptions of fuel delivery throughout the system. The tanks in question are 

designed to have support legs no higher than one foot and a bottom sloped to a sump such that no 

product or sludge remains on the tank walls or bottom after emptying. Vapor sampling indicates 

that the tanks are maintained in a vapor tight condition even while the roof has landed. 

Response 

Allowing tanks to land floating roofs without restriction would lead to excessive fugitive 

emission losses. There are very high concentrations of vapor in a relatively large vapor space 

that may be lost to atmosphere if precautions are not taken. Most facilities vent such emissions 

to a control device. However, for tanks with minimal vapor space designed to drain-dry, 

maintaining the tank in a vapor tight condition and venting vapors displaced during refilling 

would adequately control emissions. Such tanks shall be monitored on a monthly basis to verify 

that they remain in vapor tight condition. 

PAR 1149 has been revised to control floating roof landings when 1) The vapors are vented to a 

control device; or 2) The tank has been emptied of liquid and gas-freed (Gas-freed means that 

the vapor concentration within the tank is less than 5,000 ppmv, measured as methane). 

Additionally, in lieu of meeting the above requirements, drain-dry breakout tanks may maintain 

a vapor tight condition outside the tank shell. Vapor tight means that the vapor concentration 

outside the shell of the tank is less than 500 ppmv, measured as methane. 

Comment 21 

The 2.3 volume air exchanges requirement should be maintained in PAR 1149 specifically for 

non-pipeline drain-dry tanks. The drain-dry tanks have minimal product residual and controlling 

the vapors for 2.3 air exchanges should be sufficient to control vapors to 5,000 ppmv. Requiring 

a measurement would compel the terminal to access the tank and result in more emissions to the 

atmosphere than would the use of the 2.3 air exchanges. 

Response 

The 2.3 volume air exchange requirement is a calculation that would reduce the vapor 

concentration by 90 percent. If the vapor space in the tank is near complete saturation, the 

vapor concentration may be higher than 300,000 ppm. Reduction by 90 percent would leave 

over 30,000 ppm remaining in the tank. This would be substantially higher than the proposed 

limit. While requiring a measurement would lead to some negligible amount of fugitive 

emissions, the value of being able to verify compliance justifies the negligible loss.
Final Staff Report ________________________________

Proposed Amended Rule 1149 27 April 2008

Comment 22 

PAR 1149 appears to require notification whenever the roof lands. With numerous landings 

each day, we would be required to make several notification reports per day and pay hundreds of 

thousands of dollars of notification fees each year. This is an unreasonable financial and 

reporting burden. 

Response 

The notification requirements in PAR 1149 apply only to when a tank or pipeline is cleaned and 

degassed meaning that the liquid is emptied from the tank or pipeline and the vapor is removed 

until the tank or pipeline is considered gas-freed. Tank roof landings where the tank is not made 

gas-free do not require notification. In those situations, the tanks are vented to a permitted 

control device with specific permit conditions for control, monitoring and recordkeeping. 

Regardless, vapors still must be controlled when refilling the tank per the requirements of Rule 

463. 

Comment 23 

Paragraph (c)(5) regulating VOC emissions from vacuum trucks used in pipeline and tank 

degassing operations has a more restrictive requirement of 500 ppmv which is normally a limit 

for control equipment. In paragraph (c)(4), the vapor leak limit for equipment is 5,000 ppmv. 

For consistency, we suggest the use of the 5,000 ppmv limit for vacuum truck exhaust as it is not 

considered a control equipment. 

Response 

Vacuum trucks in the AQMD have been used both as equipment and as “control devices” when 

outfitted with carbon canisters. When used as equipment venting to a permitted control device, a 

vacuum truck would only need to meet the vapor leak requirement of 5,000 ppmv, measured as 

methane. However, if the VOC concentration of the vapors is 5,000 ppmv or greater, they are 

considered a regulated material and those vapors must be controlled to less than 500 ppmv 

VOC. Therefore, the vacuum truck must meet the more stringent limit of 500 ppmv, measured as 

methane, which is consistent with the requirements that all other AQMD VOC control devices 

must meet. 

Comment 24 

The requirement for monitoring using an approved instrument “measured as methane” basically 

says use a Foxboro TVA 1000 FID as no other instrument meets the requirements. We have 

approval letters from AQMD for use of PID which are calibrated and measured as methane. The 

language should be limited to say, “EPA Method 21 Instrument”. 

Response 

The requirement for monitoring using EPA Method 21, measured as methane, comes directly 

from the language of the existing rule. Vapor leaks have required this procedure prior to this 

amendment and the vapor concentration standards apply to vapor leaks to the tanks and 

pipelines as well. EPA Method 21 does not specify any particular type of monitoring equipment. 

Staff is aware of other devices that can measure vapor concentration using EPA Method 21, 

measured as methane. Permit conditions that require other types of measurements such as 

vapor concentration measured as hexane or benzene concentration limits will also need to be 

fulfilled in order to demonstrate compliance with those particular permit conditions. 
Final Staff Report ________________________________

Proposed Amended Rule 1149 28 April 2008

Comment 25 

There is nothing that specifies when to commence degassing. I suggest specifying a time period 

when degassing should commence. 

Response 

Once a tank has been emptied, it is subject to Rule 1149. At that time, the tank must be free of 

vapor leaks and may not be opened to atmosphere until the vapor concentration within the tank 

has been shown to 5,000 ppmv or less, measured as methane. If the tank has a floating roof, 

then immediately after the roof has landed and the tank is drained empty, the vapors must be 

controlled per the requirements of paragraph (c)(2). 

Comment 26 

There is nothing that specifies that you can use a degassing unit to “refloat” the roof after 

cleaning and degassing. I suggest eliminating the words “during a product change”. 

Response 

The phrase “during a product change” has been removed and now refers more generally to all 

tank roof landings. However, refilling operations are subject to the requirement of Rule 463 and 

are not subject to the requirements of Rule 1149. 

Comment 27 

I suggest you eliminate the monitoring requirements contained in paragraph (c)(8). The 

requirement to have a monitor “installed and operated” at the exit might suggest that it is 

permanent. This is just not practical, feasible or reasonable. I strongly urge that the abatement 

device monitoring requirements be left to the permit conditions. 

Response 

The language contained in paragraph (c)(7) has not changed from previous versions of the 

regulation. The rule will be clarified to limit the applicability of the continuous organic vapor 

analyzer to carbon adsorption systems used for degassing. Carbon adsorption units used for 

degassing operations will have to continue meeting the requirements of the rule and any 

additional conditions established by the permit to operate. 

Comment 28

While the California Air Resources Board believes that fuel usage should be included when 

quantifying Greenhouse gas reductions, the fuel usage should not be multiplied by the global 

warming potential of methane.

Response

Staff agrees and the calculation has been modified accordingly. 

COMPARATIVE ANALYSIS

Health and Safety Code Section 40727.2 requires a written analysis comparing the 

proposed amended rule with existing AQMD and federal regulations. Federal regulations 

do not require control of vapors from degassing operations but 40 CFR Part 280 does 

require underground storage tanks to be empty before removal. No other AQMD 

regulations apply to storage tank or pipeline degassing. 
Final Staff Report ________________________________

Proposed Amended Rule 1149 29 April 2008

SOCIOECONOMIC ASSESSMENT

A socioeconomic analysis of the amendments to Rule 1149 is included in Attachment G. will be 

performed. This analysis will be released no later than 30 days prior to the AQMD Governing

Board hearing.

CALIFORNIA ENVIRONMENTAL QUALITY ACT (CEQA)

Pursuant to the California Environmental Quality Act (CEQA) and AQMD Rule 110, 

appropriate documentation will be prepared to analyze any potential adverse environmental 

impacts associated with the proposed amendments to Rule 1149. Comments received at the 

public workshop and CEQA scoping meeting will be considered when preparing the CEQA 

document. 

DRAFT FINDINGS UNDER THE CALIFORNIA HEALTH AND SAFETY CODE

Health and Safety Code Section 40727 requires that prior to adopting, amending or repealing a 

rule or regulation, the AQMD Governing Board shall make findings of necessity, authority, 

clarity, consistency, non-duplication, and reference based on relevant information presented at 

the hearing. The draft findings are as follows: 

Necessity – State and federal health-based ambient air quality standards for ozone are regularly 

exceeded in the AQMD. The reduction of VOC from the proposed amendments to Rule 1149 is 

part of a comprehensive strategy necessary to meet federal and State air quality standards. 

Authority - The AQMD Governing Board obtains its authority to adopt, amend, or repeal rules 

and regulations from Health and Safety Code Sections 39002, 40000, 40001, 40440, 40441, 

40702, 41508, and 41700. 

Clarity - The AQMD Governing Board has determined that the proposed amendments to Rule 

1149 – Storage Tank and Pipeline Cleaning and Degassing, are written and displayed so that the 

meaning can be easily understood by persons directly affected by them. 

Consistency - The AQMD Governing Board has determined that Proposed Amended Rule 1149 

– Storage Tank and Pipeline Cleaning and Degassing, is in harmony with, and not in conflict 

with or contradictory to, existing statutes, court decisions, federal or state regulations. 

Non-Duplication - The AQMD Governing Board has determined that the proposed amendments 

to Rule 1149 – Storage Tank and Pipeline Cleaning and Degassing, do not impose the same 

requirement as any existing state or federal regulation, and the proposed amendments are 

necessary and proper to execute the powers and duties granted to, and imposed upon, the 

AQMD. 

Reference - In adopting this regulation, the AQMD Governing Board references the following 

statutes which the AQMD hereby implements, interprets or makes specific: California Health 

and Safety Code sections 40001, 40440, and 40702. 

REFERENCES

AIRx Testing. March 1999. IC Engine Emissions Test Report: Oxides of Nitrogen, Carbon 

Monoxide, Reactive Organic Gases & Benzene Emissions from a ROG Destruction Unit. 
Final Staff Report ________________________________

Proposed Amended Rule 1149 30 April 2008

California Air Resources Board. October 2007. Expanded List of Early Action Measures to 

Reduce Greenhouse Gas Emissions in California Recommended for Board Consideration.

California Office of the State Fire Marshall. 2006. Pipeline Safety Program web site. 

California Energy Commission. April 2003. California Marine Petroleum Infrastructure. 

Department of Energy, Energy Information Administration, Voluntary Reporting of Greenhouse 

Gases Program (Emission Coefficients). 

San Joaquin Valley Unified Air Pollution Control District. March 2005. Final Draft Staff 

Report for Proposed Amendments to Rule 4623 (Storage of Organic Liquids). 

SCAQMD. October 1987. Staff Report for Proposed Rule 1149 – Storage Tank Degassing. 

SCAQMD. June 1995. Final Staff Report for Proposed Amended Rule 1149 – Storage Tank 

Degassing. 

SCAQMD. 2007. General Instruction Book for the 2006-2007 Annual Emissions Reporting 

Program 

Sung, Hung-Ming (Sue). Trinity Consultants. July 2004. Testing VOC Evaporation Losses from 

Floating Roof Tank Turnovers. 

U.S. EPA. September 2006. Emission Factor Documentation for AP-42, Section 7.1, Organic 

Liquid Storage Tanks. 

World Resources Institute. June 2006. Discussion Paper for a Natural Gas Transmission and 

Distribution Greenhouse Gas Reporting Protocol 
Final Staff Report - Appendix A ________________________________

Proposed Amended Rule 1149 A - 1 April 2008

Appendix A – Tank Degassing Logs 

In Appendix A, the volume refers to amount of cubic feet in the tank needed to be degassed. The 

expected emissions are calculated from the ideal gas law methodology for the volume and 

product contained in the tank. The actual emissions are taken from the tank degassing logs and 

reflect the total pounds of VOC controlled before the operation was stopped. The actual 

emissions when 2.3 Q was reached is the amount of pounds of VOC controlled when the current 

Rule 1149 requirement of 2.3 air exchanges was met. Emissions from the degassing logs are 

calculated by determining the vapor concentration going into the control device and then 

determining the hourly pounds of emission controlled as the flow and vapor concentration 

change over time. In addition to other information, the degassing logs note the air flow from the 

tank, the vapor concentration from the tank, the air flow going into the control device and the 

time. 

Vapor concentration to the control device is calculated by multiplying the inlet vapor 

concentration from tank to ratio of the air flow from the tank over the overall air flow into the 

control device. 

E = (C * M * F * T) / (V * 1,000,000) 

where: 

E = emissions, lb 

C = concentration of vapor going into the control device, ppmv 

M = molecular weight of vapor, lb/lb-mole 

F = air flow to control device, cfm 

T = time, minutes 

V = molar volume 

and C = I * (A / F) 

where: 

C = concentration of vapor going into the control device, ppmv 

I = concentration of vapor from the storage tank, ppmv 

A = air flow from the storage tank, cfm 

F = air flow to control device, cfm 

Tank 

Capacity 

(cubic 

feet) 

Expected 

emissions 

from ideal 

gas law 

(lb) 

Actual 

emissions 

reduced 

from 

degassing 

logs (lb) 

Actual 

emissions 

reduced from 

degassing logs 

when 2.3 Q 

reached (lb) Product 

Actual vs. 

Expected 

2.3 Q vs. 

Expected 

1 106,029 6,729 1,988 824 Gasoline 29.54% 12.25%

2 22,620 402 1,476 280 Sour Naphtha 367.16% 69.65%

3 44,872 2,848 253 102 Gasoline 8.90% 3.59%

4 21,154 376 2,670 224 Sour Naphtha 710.11% 59.57%

5 83,095 2,983 95 81 Sour Water 3.18% 2.72%

6 11,133 706 279 100 Gasoline 39.52% 14.16%

7 7,921 502 346 177 Gasoline 68.93% 35.28%
Final Staff Report - Appendix A ________________________________

Proposed Amended Rule 1149 A - 2 April 2008

8 40,212 2,552 5,322 1,856 Isomerate 208.54% 72.73%

9 15,708 997 404 266 Isomerate 40.48% 26.67%

10 83,095 5274 197 184 Gasoline 3.74% 3.49%

11 76,027 4790 1,521 1,163 Gasoline 31.75% 24.27%

12 157,284 9909 2,209 1,654 Gasoline 22.29% 16.69%

13 114,512 7214 4,309 2,850 Gasoline 59.73% 39.51%

14 56,143 3537 11,592 1,760 Gasoline 327.72% 49.77%

15 90,478 5700 525 266 Gasoline 9.21% 4.66%

16 95,108 5992 2,691 2,662 Gasoline 44.92% 44.43%

17 16,964 609 1,720 100 Gasoline 282.45% 16.45%

18 75,218 4739 5,775 466 Gasoline 121.86% 9.84%

19 28,066 774 731 189 Gasoline 94.44% 24.40%

20 1,257 80 100 64 Transmix 125.45% 79.65%

21 15,708 997 14 14 Sour Naphtha 1.38% 1.38%

22 6,597 733 17 15 Brine Water 2.28% 2.10%

23 153,726 5518 1,627 588 Alkylate 29.49% 10.66%

24 50,894 840 247 172 Ethanol 29.43% 20.48%

25 11,133 183 220 145 Ethanol 120.08% 79.21%

26 80,000 2,872 1,690 1,266 Crude Oil 58.84% 44.08%

27 55,000 1,974 462 Not reported Crude Oil 23.40% 21.06%

28 40,000 1,436 952 Not reported Crude Oil 66.30% 59.67%

29 76,440 5,104 2,969 499 Gasoline 58.17% 9.77%

30 21,434 2,384 6,177 1,007 Gasoline 259.10% 42.24%

31 73,054 6,153 4,376 3,630 Gasoline 71.12% 59.00%

32 49,055 4,162 10,416 1,849 Gasoline 250.26% 44.43%

33 45,454 2,885 950 844 Gasoline 32.93% 29.25%

34 50,802 3224 821 736 Gasoline 25.46% 22.83%

35 113,636 7,212 1,361 1,361 Gasoline 18.88% 18.88%

36 13,369 848 1,598 289 Gasoline 188.44% 34.12%

37 50,802 3,224 234 234 Gasoline 7.25% 7.25%

38 40,107 254 34 34 Naphtha 13.44% 13.44%

39 46,791 766 114 114 Alkylate 14.91% 14.91%

40 46,791 766 209 186 Alkylate 27.34% 24.32%

41 46,791 766 490 239 Alkylate 64.03% 31.23%

42 46,791 766 220 198 Alkylate 28.66% 25.86%

43 16,956 1,076 245 125 Gasoline 22.75% 11.62%

44 11,775 747 191 79 Gasoline 25.59% 10.61%

45 105,975 6,726 1,242 927 Gasoline 18.46% 13.78%

46 105,975 6,726 2,472 881 Gasoline 36.75% 13.10%

47 11,775 747 206 193 Gasoline 27.52% 25.87%

48 21,143 60 99 99 Ethanol 164.79% 164.79%

49 13,734 871 203 174 Gasoline 23.33% 19.98%

50 11,775 77 40 40 Ethanol 51.91% 51.91%

51 40,107 144 66 57 Transmix 46.00% 39.47%

52 16,956 608 19 13 Transmix 3.12% 2.21%

53 65,582 4162.4 10,417 1,849 Gasoline 250.26% 44.42%

54 97,667 6199 4,376 3,630 Gasoline 70.60% 58.56%

55 28,656 1028 6,177 1,007 Crude Oil 600.88% 97.97%

56 113,636 7,212 1,815 1,742 Gasoline 25.17% 24.15%

Total 2,942,983 156,163 106,969 39,506 all (total) 68.50% 25.30%
Final Staff Report - Appendix B ________________________________

Proposed Amended Rule 1149 B - 1 April 2008

Appendix B – Time to Complete Degassing 

The information in Appendix B was evaluated to determine the increase in time required to meet 

the proposed vapor concentration limit of 5,000 ppmv. Various degassing contractors submitted 

degassing logs for tanks they had degassed over the previous year. The tanks listed met the 

criteria that they both were degassed until the current rule requirement of 2.3 air exchanges was 

met and degassed until the proposed rule requirement of 5,000 ppmv (ten percent LEL) was met. 

Not all tanks met the dual criteria and those that did not were not included. The average times to 

reach 2.3 air exchange and the proposed concentration limit were calculated and are used to 

determine how much longer, on average, it will take to degas tanks to the new standard. This 

information is used to calculate both increased costs and increased secondary emissions created 

from associated control equipment such as internal combustion engines and thermal oxidizers. 

Tank 

Time to Reach 2.3 Air 

Exchanges (hours) 

Time to Reach Proposed 

Concentration Limit (hours) 

A2 3 11 

A3 6 22 

A4 3 20 

A5 2 3 

A6 2 7 

A7 1 4 

A8 6 34 

B1 4 7 

B2 3 4 

B3 7.5 12.5 

B4 10 17 

B6 8 18 

B8 7 7 

B9 13 23 

B10 2 8 

B11 4 23 

B12 2 16 

B14 1 4 

B15 1 1 

B16 4 9.5 

B17 1 2 

B19 5 11 

B20 1 3 

B22 11 40 

C1 45 57 

C2 13 74 

C3 20 127 

D1 8 5 

D2 3.5 5 

D3 6 4.5 

Total (hrs) 203 579.5 

Average (hrs) 8.5 24.1