Aboveground and underground storage tanks
Department Editor: Scott Jenkins he ultimate objective of storing liquid, fluid and gaseous products, which may be corrosive, flammable or unstable, is to store material in an environmentally safe and economically viable manner. Storage tanks in the chemical process industries (CPI) can be most broadly divided into those buried underground, and those constructed aboveground. The following is an outline of considerations associated with each category and positive and negative aspects of each. Also included are potentially applicable regulations and codes from the U.S. Environmental Protection Agency (EPA), (EPA ), the Occupational Health and Safety Administration (OSHA) and others.
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UNDERGROUND STORAGE TANK (UST) ADVANTAGES Physical safety — USTs are out of the way of automobile traffic Fire safety — With a relatively constant underground temperature, USTs have superior vapor suppression and fire protection for flammable and volatile contents, as well as a reduced need for fire hazard permits Security — The American Petroleum Institute has shown that vandalism is a leading cause of tank failures. USTs are less subject to vandalism and easier to protect Aesthetics — USTs are out of sight, which eliminates a possible public objection Land use — USTs offer a more efficient use of land space and allow more flexibility in placement location
UST DISADVANTAGES Leak detection and containmen containmentt — Leak monitoring, detection and containment is more difficult and more expensive underground Installation complexity and cost — Excavation and special backfill materials add costs Depreciation — Real estate depreciation is possible due to threat of contamination
ABOVEGROUND STORAGE TANK (AST) ADVANTAGES Construction — ASTs are simpler and less expensive to construct and install. One significant aspect eliminated is the need for excavation and special backfill materials Maintenance — Visual inspection is possible, which leads to more reliable leak detection and easier repair Insurance — Lower pollution insurance premiums because of reduced risk of groundwater contamination Regulatory burden — ASTs are subject to less regulatory requirements than t han USTs Costs — ASTs have lower monitoring and
REGULATIONS AND CODES POTENTIALLY APPLICABLE TO UST AND AST
Regulation name
Applicability
Governing Body
Resource Conservation and Recovery Act Subtitle C — hazardous waste regulations
AST and UST
EPA
Spill Prevention, Control and Countermeasures within Clear Air Act amendments of 1990
AST and UST
EPA
Hazardous Waste Operations and Emergency Response Regulations — 29 CFR 1910.120
AST and UST
OSHA
Flammable and Combustible Liquids Standard — 29 CFR 1910.106
AST and UST
OSHA
Hazard Haz ard Com Commun munica icatio tion n St Stand andard ard — 29 CFR 191 1910.1 0.1200 200
AST and UST
OSHA OSH A
Confine Con fined d Spa Space ce Saf Safety ety St Stand andard ard — 29 CFR 191 1910.1 0.146 46
AST and UST
OSHA OSH A
Oil Pollution Act of of 1990
AST only
EPA
Nati Na tion onal al Po Poll llut utan antt Di Disc scha harg rge e El Elim imin inat atio ion n Sy Syst stem em
ASTT on AS only ly
EPA EP A
Comprehensive Environmental Response, Compensation Compensation and Liability Act (CERCLA)
AST only
EPA
Benzene — 29 CFR 1910.1028
AST only
OSHA
Process Safety Management of Highly Hazardous Chemicals, Explosives Explosives and Blasting Ag ents — 29 CFR 1910.119
AST only
OSHA
Resource Conservation and Recovery Act Subtitle I — regulations addressing USTs storing petroleum and hazardous substances — 40 CFR 280
UST only
EPA
Stage II Vapor Vapor Recovery Regulations — established in Clean Air Act Amendments of 1990
UST only
EPA
Clea Cl ean n Ai Airr Ac Actt Ti Titl tle e V — op oper erat atin ing g pe perm rmit itss
USTT onl US nly y
EPA
Emergency planning and Community Right-to-know Act — UST only Title III of Superfund Amendments and Reauthorization Act.
EPA
National Fire Protection Association NFPA 30 (Flammable and Combustible Liquids Code)
AST and UST
NFPA code
Inter Int erna natio tiona nall Cod Code e Cou Counc ncil il (IC (ICC) C) Int Inter erna natio tiona nall Fir Fire e Cod Code e
AST an and d UST UST
ICC IC C cod code e
AST DISADVANTAGES
and federal requirements. Regulatory frameworks are different for AST and UST
Physical safety — ASTs are more vulnerable to vandalism, contact with automobiles and external damage Fire safety — ASTs have an elevated fire risk relative to USTs Aesthetics — ASTs may be objectionable in certain locations Space use — more real estate required to house ASTs Temperature variation — ASTs experience greater ambient-prod ambient-product-temperature uct-temperature fluctuations than USTs
Space — Space requirements to separate an AST from traffic, buildings, property lines, present and future can be significant, while they are not an issue for USTs. Fire codes generally dictate separation distances Security — Protection from vandalism is more difficult for ASTs Cost — Several aspects of cost should be considered, including: storage tank, tank system equipment, initial installation cost, ongoing maintenance cost, security cost, land cost, regulatory cost and secondary containment cost
MAKING THE CHOICE When making decisions about whether to use an AST or a UST, consider the following:
Regulatory — The local authority in the area where the tank system will be assembled has control of whether a tank permit will be issued, based on whether
References:
1. Geyer, W.B. To Bury or Not to Bury: Steel Tank Technology Decisions. In: “Handbook of Storage Tank Systems,” Marcel Dekker, New York, 2000. 2. Cheremisinoff, P.N., and Vallamar, O. Aboveground and Underground Storage Tank Comparison. In: “Storage Tanks. Advances in Environmental Control Te Technology chnology Series,”
