Rule 900 Definitions
ADOPTED April 17, 1989
AMENDED September 18, 1990

Any addition to, enlargement of, replacement of, or any major modification or change of the design, capacity, process, or arrangement, or any increase in the connected loading of equipment or control apparatus, which will significantly increase or effect the kind or amount of air contaminants emitted

The Air Pollution Control Officer of the Air Pollution Control District of El Dorado County.

The California State Air Resources Board, or any person authorized to act on its behalf.

ARB-Certified Vapor Recovery System.
A vapor recovery system which has been certified by the state board pursuant to Section 41954 of the Health and Safety Code.

Bottom Loaded.
A gasoline delivery vessel shall be considered to be bottom loaded when the fuel transfer and vapor return lines have separate, independent, and dedicated attachments on the truck or tank, when the inlet is flushed with the tank bottom, and when the truck and trailer hatches remain closed during fuel transfer.

Bulk Facility
An intermediate gasoline distribution facility consisting of gasoline loading facilities where delivery to the facilities storage containers is by tank truck.

The maximum volumetric quantity of liquid that may be stored in a tank.

Criteria Pollutant.
An air pollutant regulated by a national ambient air quality standard contained within 40 CFR Part 50.

A comparison of controlled emissions to those emissions which would occur from a fixed or cone roof tank in the same product service without a vapor control system. Base line emissions shall be calculated by using the criteria outlined in American Petroleum Institute Bulletin 2518.

Exposure to view by digging.

Existing Retail Service Station.
Any retail service station operating, constructed, or under construction as of 04-17-89.


Any property, real or personal, which is operated or maintained by a person/s as part of an identifiable business.

Floating Roof.
A pontoon-type or double-deck type roof, resting on the surface of the liquid contents and equipped with a closure seal, or seals, to close the space between the roof edge and tank wall. The control equipment provided for in this section shall not be used if the gasoline or petroleum distillate has a vapor pressure of 11.0 pounds per square inch absolute or greater under actual storage conditions. All tank gauging and sampling devices shall be gas-tight except when gauging or sampling is taking place.

Gas Tight.
The concentration of total hydrocarbons, measured 1 cm from any source, not to exceed 10,000 ppm (expressed as methane) above background, as determined by EPA Reference Method 21. Background shall be defined as the ambient concentration of organic compounds determined at least three (3) meters upwind of the potential source and not influenced by any specific emissions source.

Any organic liquid (including petroleum distillates and methanol) having a Reid vapor pressure of four (4) pounds or greater and used as a motor vehicle fuel or any fuel which is commonly or commercially known or sold as gasoline.

Gasoline Bulk Terminal.
A distributing facility which receives gasoline, stores it in stationary tanks, and loads it into tank trucks for delivery to gasoline bulk plants, service stations or other distribution points.

Gasoline Storage Tank.
Any storage container, reservoir, or tank used for the storage of gasoline that is equipped with no vapor control, or is equipped with splash loading, or Phase I or Phase II vapor recovery loading systems.

Gasoline Vapors.
The organic compounds in the displaced vapors including any entrained liquid gasoline.

Leak Free.
A liquid leak of less than three drops per minute excluding losses which occur upon disconnecting transfer fittings, provided such disconnect losses do not exceed 10 milliliters (0.34 liquid ounces) per disconnect, averaged over three continuous disconnects.

Motor Vehicle.
As defined in Section 415 of the Vehicle Code.

Offset Fill Pipe.
Means any pipe containing horizontal lengths of pipe which prohibit the installation of a submerged fill pipe.

Organic Liquid.
All precursor organic compounds which contain hydrogen and which would exist as liquids at actual conditions of use or storage.

Owner or Operator.
Any person who owns, operates, controls, or supervises an affected facility, or a stationary source of which an affected facility is a part.

Phase I Vapor Recovery System.
An ARB-certified gasoline vapor recovery system which recovers vapors during the transfer of gasoline from delivery vessels into stationary storage tanks.

Phase II Vapor Recovery System.
An ARB-certified gasoline recovery system which recovers vapors during the fueling of motor vehicles from stationary storage tanks.

Precursor Organic Compound.
Any compound of carbon which participates in atmospheric photochemical reactions, excluding any of the following:

methane, ethane, carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, ammonium carbonate, 1,1,1 trichloroethane, methylene chloride, trifluoromethane (FC - 23),
trichlorotrifluoroethane (CFC-113),
dichlorodifluoromethane (CFC-12),
trichlorofluoromethane (CFC-11),
chlorodifluoromethane (CFC-22),
dichlorotetrafluoroethane (CFC-114),
chloropentafluoroethane (CFC-115),
dichlorotrifluoroethane (HCFC-123),
tetrafluoroethane  (HFC-134a), 
dichlorofluoroethane (HCFC-141b),and 
chlorodifluoroethane (HCFC-142b)
These compounds, as listed above, have been determined to have negligible photochemical reactivity. For purposes of determining compliance with emission limits, VOC will be measured by the approved test methods. Where such a method also inadvertently measures compounds with negligible photochemical reactivity, an owner or operator may exclude these negligibly reactive compounds when determining compliance with an emissions standard.

Pressure Tank.
A tank which maintains working pressure sufficient at all times to prevent hydrocarbon vapor or gas loss to the atmosphere.

Retail Service Station.
Any new or existing motor vehicle fueling service station subject to payment of California sales tax on gasoline sales.

Storage Tank.
Any stationary container, reservoir, or tank used for the storage of organic liquids.

Submerged Fill Pipe.
Any fill pipe which has its discharge opening entirely submerged when the liquid level is six inches (6") above the bottom of the tank. "Submerged fill pipe", when applied to a tank which is loaded from the side, means any fill pipe which has its discharge opening entirely submerged when the liquid level is eighteen inches (18") above the bottom of the tank.

Switch Loading.
The transfer of organic liquids with a Reid Vapor Pressure of less than 4.0 lbs into a delivery vessel where the previous load was gasoline.

Tank Replacement.
Replacement of one or more stationary storage tanks at an existing retail service station or excavation of 50 percent or more of an existing retail service station's total underground liquid piping from the stationary storage tanks to the gasoline dispensers.

A primary distributing plant which receives organic liquid; stores it in stationary tanks; loads it into transportable containers, excluding marine vessels, for delivery to bulk plants, service stations or other distributing points; and which has an annual throughput of more than 23,000 cubic meters (6,000,000 gallons).

The volume of gasoline dispensed at a facility.

Topping Off.
To attempt to dispense gasoline to a motor vehicle fuel tank after a vapor recovery dispensing nozzle has shut off automatically. The filling of those vehicle tanks which, because of the nature and configuration of the fill pipe, causes premature shut off of the dispensing nozzle, and which are filled only after the seal between the fill pipe and the nozzle is broken, shall not be considered topping off.

Vapor Leak.
Any source of gasoline vapors which cause a combustible gas detector meter reading of 100 percent of the Legal Exposure Level. A marginal vapor leak may be verified by conducting a pressure/vacuum leak test. A vapor leak does not include any vapor resulting from liquid spillage or liquid leaks.

Vapor Recovery System.
A vapor gathering system capable of collecting and or destroying hydrocarbon vapors and gases that are normally discharged to the atmosphere during a transfer of organic liquid from one container to another container.

Vapor Tight.
A leak of less than 100 percent of the lower explosive limit on a combustible gas detector measures at a distance of 2.5 cm (one inch) from the source or no visible evidence to air entrainment and no visible evidence of air entrainment in the sight glass of a liquid delivery hose.