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Source: Emissions and Dispersion Modeling System (EDMS) User’s Manual , FAA-AEE-07-01 (Rev. 10 – 06/07/13), June 2013, http://www.faa.gov/about/office_org/headquarters_offices/apl/research/models/edms_model/media/EDMS_5.1.4_ User_Manual.pdf, and Chapter 7, Organic Liquid Storage Tanks, of EPA's AP-42, http://www.epa.gov/ttnchie1/ap42/ch07/. 

Notes: 1 

Tanks listed are typically above ground storage tanks, except for horizontal fixed roof tanks which can be constructed for both above-ground and underground service. 

$^{2 }$In general, fixed-roof tanks tend to be older and result in the greatest atmospheric emissions. The presence of a volume of vapor space above the level of liquid in the tank promotes evaporation of the fuel hydrocarbons and their subsequent release to the atmosphere through the breather valve. 3 

Tanks equipped with a floating roof are able to reduce evaporative emissions by eliminating the vapor sp between the liquid level in the tank and the tank roof. However, some emissions do occur through various seals and 

