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RULE 4621 GASOLINE TRANSFER INTO STATIONARY STORAGE CONTAINERS, 

DELIVERY VESSELS, AND BULK PLANTS (Adopted April 11, 1991; 

Amended September 19, 1991; Amended December 17, 1992; Amended May 

20, 1993; Amended June 18; 1998; Amended December 20, 2007; Amended 

December 19, 2013) 

1.0 Purpose 

The purpose of this rule is to limit VOC emissions from stationary storage containers, 

delivery vessels, and bulk plants and to provide the administrative requirements for 

determining compliance with this rule. 

2.0 Applicability 

This rule applies to storage containers located at bulk plants with capacities greater than 

250 gallons and less than 19,800 gallons; to other stationary storage containers with 

capacities greater than 250 gallons; and to those storage containers that are not subject 

to the control requirements of Rule 4623 (Storage of Organic Liquids) Section 5.0. 

The rule also applies to gasoline delivery vessels. 

3.0 Definitions 

3.1 APCO: as defined in Rule 1020 (Definitions). 

3.2 ARB: California Air Resources Board. 

3.3 ARB Certified: a vapor recovery system, equipment, or any component 

thereof, for which the ARB has evaluated its performance and issued a valid 

Executive Order pursuant to California Health and Safety Code Section 41954. 

Each component of a system that is a separate ARB certified item cannot be 

replaced with a non-certified item or other items that are not certified for use 

with the particular system. Except for qualified repairs, an ARB certified 

component shall be as supplied by the qualified manufacturer. A rebuilt 

component shall not be deemed as ARB certified unless the person who rebuilds 

the component is authorized by ARB to rebuild the designated ARB certified 

component. 

3.4 ARB Certified Phase I Vapor Recovery System: a vapor recovery system that 

has been certified by ARB pursuant to Section 41954 of the California Health 

and Safety Code. 

3.5 Aviation Gasoline: gasoline used as fuel for aircraft that cannot be legally used 

as fuel for motor vehicles. 
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3.6 Background: the ambient concentration of organic compounds determined at 

least two (2) meters upwind from any component to be inspected and which is 

uninfluenced by any specific emission permit unit. 

3.7 Bulk Plant: any loading rack and associated unloading racks, storage containers 

and vapor recovery system(s) used to load less than 20,000 gallons of gasoline 

in any one day, to delivery vessels. 

3.8 Business Day: a weekday, including Monday, Tuesday, Wednesday, Thursday, 

or Friday. 

3.9 Component: includes, but is not limited to, any valve, fitting, threaded 

connection, pump, pressure relief device, pipe, flange, hatch, sight-glass, meter, 

or seal of a fluid system in VOC service. 

3.10 Delivery Vessel: any cargo container having a volumetric capacity in excess of 

120 gallons that is used for the transportation of gasoline or aviation gasoline. 

This term includes pumps, meters, valves, fittings, piping, and other 

appurtenances attached to a gasoline storage container on a vehicle and used in 

connection with the gasoline/aviation gasoline being transported. Containers 

used exclusively for aviation gasoline in agricultural operations, with an annual 

throughput of 1,000 gallons or less, will not be considered delivery vessels for 

the purpose of this rule. 

3.11 Emergency: a fire, flood, earthquake, or other similar catastrophe. 

3.12 EPA: United States Environmental Protection Agency. 

3.13 Excess Organic Liquid Drainage: more than 10 milliliters liquid drainage which 

is not contained by an ARB certified spill container. Such liquid drainage for 

disconnect operations shall be determined by computing the average drainage 

from three consecutive disconnects at any one loading arm. 

3.14 Gasoline: any petroleum distillate, petroleum distillate/alcohol blend or alcohol 

having a Reid vapor pressure of four (4) pounds per square inch absolute or 

greater, which is used as a motor vehicle fuel, or any fuel which is commonly or 

commercially known or sold as gasoline, including aviation gasoline. 

3.15 Gasoline Vapors: VOCs in the displaced vapors of gasoline, including any 

entrained liquids. 

3.16 Highway: a way or place of whatever nature, publicly maintained and open to 

the use of the public for purposes of vehicular travel. Highway includes street. 

3.17 ICC: International Code Council. 
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3.18 Implement of Husbandry: a vehicle that is used primarily in the conduct of 

agricultural operations pursuant to Section 36000 of the California Vehicle 

Code. 

3.19 Leak: one of the following – 

3.19.1 For delivery vessels, the dripping of VOC-containing liquid at a rate of 

more than three (3) drops per minute, or a reading of greater than 100 

percent of the lower explosive limit (21,000 ppm measured as equivalent 

propane) when measured in accordance with the test method in Section 

6.4.3. 

3.19.2 For all other operations, the dripping of VOC-containing liquid at a rate 

of more than three (3) drops per minute, or the detection of any gaseous 

or vapor emissions with a concentration of total organic compound 

greater than 10,000 ppmv, as methane, above background when 

measured in accordance with the test method in Section 6.4.2. Any 

liquid or gas coming from a component undergoing repair or 

replacement, or during sampling of process fluid from a component or 

equipment into a container is not considered sampling of a leak, provided 

such activities are done as expeditiously as possible and with minimal 

spillage of material and VOC emissions to the atmosphere. 

3.20 Leak-free: a condition without a leak, as defined above. 

3.21 Loading Operation: any aggregate or combination of gasoline loading and 

vapor control equipment from the connection at the inlet of the gasoline pump to 

and including the hose end connector at the portable delivery tanks and the 

discharge of the vapor control device(s). 

3.22 Loading Rack: as defined in Rule 1020 (Definitions). 

3.23 Major Modification: one of the following – 

3.23.1 The addition, replacement, or removal of an underground storage 

container, or a modification that causes the container top to be unburied, 

is considered a major modification, or 

3.23.2 The replacement of an aboveground storage container. The installation 

of an aboveground storage container after retrofitting with standing loss 

controls or the exchange of an aboveground storage container for a 

standing loss control retrofitted aboveground storage container of equal 

capacity to comply with the requirements of CP-206 is not a major 

modification. 
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3.24 Mobile Fueler: any gasoline delivery vessel with an attached container that is 

used to transport and dispense gasoline from an onboard storage container into 

any motor vehicle fuel tank. 

3.25 Motor Vehicle: a vehicle that is self propelled. 

3.26 Normal Business Hours: Monday through Friday, 8:00 am to 5:00 pm. 

3.27 Operator: any person that owns, leases, or operates a facility that dispenses or 

transfers gasoline or that owns, leases, or operates a delivery vessel that 

dispenses or transfers gasoline. 

3.28 Portable Hydrocarbon Detection Instrument: a hand-held hydrocarbon analyzer 

that meets the criteria specified in US EPA Method 21, 40 CFR Part 60. The 

instrument shall be calibrated with methane. 

3.29 Pressure Vacuum Relief Valve: a valve that is installed on the gasoline storage 

container or the vent pipes of gasoline storage containers to relieve pressure or 

vacuum build-up at preset values of pressure or vacuum. 

3.30 Retail Gasoline Outlet: any establishment at which gasoline is sold or offered 

for sale to the general public for use in motor vehicles. 

3.31 Submerged Fill Pipe: any fill pipe, the discharge opening of which is entirely 

submerged when the liquid level is six (6) inches above the bottom of the 

container. "Submerged fill pipe" when applied to a container which is loaded 

from the side is defined as any fill pipe the discharge opening of which is 

entirely submerged when the liquid level is 18 inches above the bottom of the 

container. 

3.32 Switch Loading: the transfer of diesel fuel into a delivery vessel or storage 

container with a capacity over 250 gallons which previously contained gasoline. 

3.33 Vehicle: a device by which any person or property may be propelled, moved, 

or drawn upon a highway, excepting a device moved exclusively by human 

power or used exclusively upon stationary rails or tracks. 

3.34 VOC: as defined in Rule 1020 (Definitions). 
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4.0 Exemptions 

Except for the provisions of Section 6.1.1, the requirements of this rule shall not apply 

to the following operations: 

4.1 The transfer of gasoline into any stationary storage container with a capacity of 

550 gallons or less used primarily for the fueling of implements of husbandry, if 

such container is equipped with a permanent submerged fill pipe. 

4.2 The transfer of gasoline into any stationary storage container having a capacity 

of 2,000 gallons or less which was installed prior to July 1, 1975, if such 

container is equipped with a permanent submerged fill pipe, and provided no 

major modification is made on the container. 

4.3 The transfer of gasoline into any stationary storage container in existence prior 

to July 1, 1975, which is equipped with an offset fill pipe if such container is 

equipped with a permanent submerged fill pipe, and provided no major 

modification is made on the container. 

4.4 Mobile fuelers used exclusively for fueling emergency motor vehicles while on 

location at an emergency. 

5.0. Requirements 

5.1 Loading equipment and vapor collection equipment shall be installed, 

maintained, and operated such that it is leak-free, with no excess organic liquid 

drainage at disconnect. 

5.2 Gasoline Storage and Loading 

5.2.1 In addition to the requirements of Section 5.1 no person shall transfer or 

permit the transfer of gasoline from any delivery vessel into any 

stationary storage container subject to requirements of this rule unless: 

5.2.1.1 Such container, except those used for aviation gasoline, is 

equipped with an ARB certified permanent submerged fill pipe 

and utilizes an ARB certified Phase I vapor recovery system 

that is maintained and operated according to manufacturer 

specifications and the applicable ARB Executive Order; or 

5.2.1.2 Containers used for aviation gasoline are equipped with a 

permanent submerged fill pipe and a Phase I vapor recovery 

system that is certified (or was previously certified) to meet a 

minimum volumetric control of 95%. 
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5.2.2 Any vent pipe on a stationary gasoline storage container shall be 

equipped with a pressure-vacuum relief valve in accordance with the 

requirements set forth in Sections 5.3 and 5.4, as applicable. 

5.2.3 Vent pipes may be manifolded, as per the applicable ARB Executive 

Order, to a single pressure-vacuum relief valve. The pressure-vacuum 

relief valve shall be properly installed and maintained according to 

manufacturer specifications and the applicable ARB Executive Order. 

5.2.4 Operators shall have all underground storage container installations and 

all underground piping configurations inspected by the APCO prior to 

backfilling. The operator shall notify the District by telephone or other 

District-approved method and obtain a confirmation number at least three 

business days prior to the backfilling. 

5.3 Underground Storage Containers 

5.3.1 Unless otherwise specified in the applicable ARB Executive Order, for 

an underground storage container that contains gasoline and is located at 

a bulk plant, the container shall be equipped with an ARB certified 

pressure-vacuum relief valve set at 3.0±0.5 inches water column 

pressure relief and 8.0±2.0 inches water column vacuum relief. 

5.3.2 Unless otherwise specified in the applicable ARB Executive Order, for 

an underground storage container that contains aviation gasoline and is 

located at a bulk plant, the container shall be equipped with a pressurevacuum relief valve set at 3.0±0.5 inches water column pressure relief 

and 8.0±2.0 inches water column vacuum relief. 

5.3.3 For an underground storage container that contains gasoline and is not 

located at a bulk plant, the container shall be equipped with an ARB 

certified Phase I vapor recovery system that is certified to have a 

minimum volumetric control efficiency of 98%. 

5.3.4 For an underground storage container that contains aviation gasoline and 

is not located at a bulk plant, the container shall be equipped with a 

permanent submerged fill pipe and a Phase I vapor recovery system that 

is certified (or was previously certified) to meet a minimum volumetric 

control of 95%. 

5.3.5 Operators of underground storage containers not located at bulk plants 

shall conduct and pass the applicable performance tests specified in 

Sections 6.4.4 through 6.4.7 to determine compliance at least once every 

36 months, (no more than 30 days before or after the required 
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performance test date) unless otherwise required under ARB Executive 

Order or Rule 4622 (Gasoline Transfer into Motor Vehicle Fuel Tanks). 

5.4 Aboveground Storage Containers 

5.4.1 All aboveground storage containers shall be constructed and maintained 

in a leak-free condition. 

5.4.2 All aboveground storage containers that contain gasoline shall be 

equipped with an ARB certified pressure vacuum relief valve set 

3.0±0.5 inches water column pressure relief and 8.0±2.0 inches water 

column vacuum relief, unless: 

5.4.2.1 Otherwise specified in the applicable ARB Executive Order, or 

5.4.2.2 Such setting will exceed the vessel’s maximum pressure rating. 

5.4.3 All aboveground storage containers that contain aviation gasoline shall be 

equipped with pressure relief valves set at eight (8) ounces per square 

inch, unless: 

5.4.3.1 Otherwise specified in the applicable ARB Executive Order or 

5.4.3.2 Such setting will exceed the vessel’s maximum pressure rating. 

5.4.4 Operators of an aboveground storage container not located at a bulk plant 

shall conduct and pass the performance test specified in Section 6.4.8 to 

determine compliance at least once every 36 months, (no more than 30 

days before or after the required performance test date) unless otherwise 

required under ARB Executive Order. 

5.5 All Phase I vapor recovery systems shall be inspected according to the 

frequency specified in Table 1. The person conducting the inspections shall, at 

a minimum, verify the following: 

5.5.1 That the fill caps and vapor caps are not missing, damaged, or loose; 

5.5.2 That the fill cap gasket and vapor cap gaskets are not missing or 

damaged; 

5.5.3 That the fill adapter and vapor adapter are securely attached to the risers; 

5.5.4 That, where applicable, the spring-loaded submerged fill tube seals 

properly against the coaxial tubing, and the dry break (poppet-valve) is 

not missing or damaged; and 
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5.5.5 That the submerged fill tube is not missing or damaged. 

Table 1 – Schedule of Maintenance Inspection 

Gasoline dispensed by the operation during largest 

monthly throughput of previous year 

Frequency of Inspections 

A. Retail Gasoline Outlets 

1. Less than 25,000 gallons One day per week 

2. 25,000 gallons or greater Five days per week 

B. Non-Retail Gasoline Outlets and other gasoline dispensing operations 

1. Less than 2,500 gallons One day per month 

2. 2,500 to less than 25,000 gallons One day per week 

3. 25,000 gallons or greater Five days per week 

5.6 Bulk Plants and Loading Racks at Bulk Plants 

5.6.1 All bulk plants shall meet one of the following requirements: 

 5.6.1.1 Bulk plants not involved with aviation gasoline loading shall be 

equipped with an ARB certified vapor recovery system for 

loading operations (loading rack). 

 

 5.6.1.2 Bulk plants involved with aviation gasoline loading shall be 

equipped with a vapor recovery system that meets a minimum 

volumetric control of 90% when measured in accordance with 

the test method specified in Section 6.4.9. 

5.6.2 The loading rack vapor recovery system shall not create a back pressure 

in excess of the pressure limits of the delivery vessel certification leak 

test (18 inches water column). 

5.6.3 Operators shall store or dispose of gasoline in closed, non-leaking 

containers. The containers shall remain closed at all times except when 

depositing or removing the contents of the containers or when the 

container is empty. 

5.6.4 Bulk Plant Leak Inspections 

5.6.4.1 All bulk plants shall be constructed and maintained in a leakfree condition. 

5.6.4.2 All bulk plants shall be inspected for leaks at least once in every 

six-month period (from four to eight months apart) in 

accordance with the test procedure specified in Section 6.4.2. 
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5.6.4.3 All loading racks located at bulk plants shall be inspected for 

leaks during product transfer at the frequency required in 

Section 5.6.4.2. 

5.6.4.4 If any storage container, storage container component, or 

loading rack component is found to leak during an inspection, 

the inspection frequency shall be changed to quarterly until the 

unit has successfully passed five consecutive quarterly 

inspections. Thereafter, the quarterly inspection may revert to 

the applicable inspection frequency specified in Section 5.6.4.2. 

5.6.5 Bulk Plant Leak Repair 

5.6.5.1 Upon detection of a leaking component, the operator shall affix 

to that component a weatherproof readily visible tag with the 

date and time of leak detection, the date and time of leak 

measurement, and for gas leaks, the leak concentration in 

ppmv. 

5.6.5.2 The tag shall remain affixed to the component until all the 

conditions specified in Sections 5.6.5.3 and 5.6.5.4 have been 

met. 

5.6.5.3 All leaking components shall be repaired or replaced within 

seven (7) business days after the leak is detected. If the 

component cannot be repaired within seven (7) business days, 

the operator must remove the leaking component(s) from VOC 

service. 

5.6.5.4 Upon returning a leaking component to service, the following 

conditions must be met. 

5.6.5.4.1 The component must be re-inspected using the test 

method specified in Section 6.4.2; and 

5.6.5.4.2 The component must be found to be in compliance 

with the requirements of this rule. 

5.7 Delivery Vessels 

5.7.1 All delivery vessels shall have an ARB certified vapor recovery system 

for cargo containers. Cargo container vapor recovery systems shall be 

maintained and tested in accordance with manufacturer specifications and 

any applicable ARB Executive Orders. 
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5.7.2 No person shall operate, or allow the operation of a delivery vessel 

unless valid State of California decals which attest to the vapor integrity 

of the container are displayed. 

5.7.3 No person shall store gasoline in, otherwise use, or operate any gasoline 

delivery vessel unless such vessel is designed and maintained to be leakfree. Any delivery vessel into which gasoline vapors have been 

transferred shall be filled only from loading racks or other delivery 

vessels that are equipped with an ARB certified vapor recovery system. 

5.7.4 The hatch on a delivery vessel shall be equipped with a leak-free cover 

and the hatch shall not be opened for visual inspection unless at least 

three minutes have elapsed since loading or unloading has stopped. The 

dome hatch, once opened, shall not be held open longer than three 

minutes, except as directed by local, state, or federal agencies having 

jurisdiction. 

5.7.5 Gasoline vapors shall not be purged into the atmosphere. This includes 

relieving container pressure by manually “popping” the poppet valve on 

the truck-mounted vapor return line. 

5.7.6 Switch loading shall not be conducted unless such transfer is made using 

a permanently installed ARB certified vapor recovery system. 

5.7.7 During loading of the delivery vessel, the truck-mounted vapor return 

line shall be connected to a vapor recovery system that meets the 

requirements of this rule for the vapor recovery systems. 

6.0 Administrative Requirements 

6.1 Recordkeeping 

6.1.1 All data necessary to demonstrate qualifications for the exemptions 

allowed in this rule shall be maintained on the premises at all times and 

shall be submitted for District, ARB, or EPA review upon request. Such 

records shall include exemption status and volume delivered to each 

stationary storage container serviced. 

6.1.2 Bulk Plants and Loading Racks: A record of all inspections and all 

actions conducted on any part of the storage container or loading racks 

shall be maintained in chronological order showing date of inspection, 

description and location of any equipment replaced, and a description of 

the problem which required repair. 

6.1.3 All bulk plants shall maintain daily gasoline throughput records. 
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6.1.4 All records required to demonstrate compliance with the requirements of 

this rule shall be retained on the premises for a minimum of five (5) 

years and made available on site during normal business hours to the 

APCO, ARB, or EPA, and submitted to the APCO, ARB, or EPA upon 

request. 

6.2 Testing Requirements 

6.2.1 Operators shall conduct all performance tests required by ARB Executive 

Order and facility installation and operations manual as per the frequency 

outline therein or as designated by the APCO. 

6.2.2 Each ARB certified Phase I vapor recovery system shall be performance 

tested within 60 days of completion of installation or modification. 

6.2.3 Bulk plants involved with aviation gasoline loading subject to Section 

5.6.1.2 shall be performance tested within 60 days of completion of 

installation or modification. 

6.2.4 Operators shall notify the District at least seven (7) days prior to any 

performance testing. 

6.2.5 Operators shall submit all performance test results to the District within 

30 days of test completion. 

6.3 Certification Requirements 

6.3.1 Installation and maintenance contractors shall: 

6.3.1.1 Be certified by the ICC for Vapor Recovery System Installation 

and Repair (VI) and make available onsite proof of ICC 

certification for VI, and 

6.3.1.2 Have and make available on site proof of any and all 

certifications required by the applicable ARB Executive Order 

and installation and operation manual in order to install or 

maintain specific systems, or 

6.3.1.3 Work under the direct and personal supervision of an individual 

physically present at the work site who possesses and makes 

available onsite a current certificate from the ICC, indicating he 

or she has passed the VI exam and all certifications required by 

the applicable ARB Executive Order. 
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6.3.2 All ICC certifications shall be renewed every 24 months by passing the 

appropriate exam specific to the certification being sought. 

6.3.3 Gasoline Dispensing Facility Testers wishing to conduct vapor recovery 

system testing and repair at facilities located within the District, shall be 

in full compliance with District Rule 1177 (Gasoline Dispensing Facility 

Tester Certification). 

6.4 Test Methods 

6.4.1 The Reid Vapor Pressure of gasoline shall be determined in accordance 

with ASTM D 5191-01. 

6.4.2 Measurements of leak concentrations, excepting delivery vessels, shall be 

conducted according to EPA Method 21 using an appropriate portable 

hydrocarbon detection instrument calibrated with methane. 

6.4.2.1 The instrument shall be calibrated in accordance with the 

procedures specified in EPA Method 21 or the manufacturer’s 

instruction, as appropriate, not more than 30 days prior to its 

use. 

6.4.2.2 The operator shall record the calibration date of the instrument. 

6.4.3 Measurements of leak concentrations for delivery vessels shall be 

conducted according to the ARB Test Procedure for Determination of 

Leaks, TP-204.3. 

6.4.4 Static Leak Test for Underground Tanks: ARB Test Procedure TP-201.3. 

6.4.5 Static Torque of Rotatable Phase I Adaptors: ARB Test Procedure TP 

201.1B. 

6.4.6 Leak Rate of Drop Tube/Drain Valve Assembly: ARB Test Procedure 

TP 201.1C. 

6.4.7 Leak Rate of Drop Tube Overfill Protection Devices and Spill Container 

Drain Valves: ARB Test Procedure TP 201.1D. 

6.4.8 Static Leak Test for Aboveground Tanks: ARB Test Procedure TP-206.3 

or ARB Test Procedure TP-201.3B as applicable. 

6.4.9 Determination of Emission Factor of Vapor Recovery Systems of Bulk 

Plants: ARB Test Procedure TP-202.1. 
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6.5 Versions of Test Methods 

All test procedures shall be conducted in accordance with the latest version of the 

test procedures, or their equivalents as approved in writing by the APCO and EPA. 
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