The Proper Handling Of Bulk Fuel Storage
While the prospect of bulk petrochemical fuel storage seems as easy as setting up a tank and filling it, there are many rules and regulations to consider. Petrochemical fuel storage regulations vary by the type of tank and its size. Only certain materials may be used for tank construction, and tanks must be placed in areas deemed safe according to EPA, NFPA, and local standards.
Types of Fuel Storage Tanks
Companies have two options for bulk petrochemical fuel storage – underground storage tanks and aboveground storage tanks. Underground storage tanks (USTs) are classified as any tank with 10% of its volume below surface grade. Aboveground storage tanks (ASTs) are just that – aboveground. These tanks have different regulatory requirements as well as logistic considerations to consider.
Underground Storage Tanks
USTs are defined by the EPA as any tank and associated piping that has at least 10% of its total volume below grade. Generally speaking, a tank with no visible bottom meets this definition.
Petroleum and hazardous waste tanks meeting the UST definition are subject to the UST provisions of 40 CFR Part 280, with the exception of:
- Storage tanks housing 110 gallons or less
- Storage tanks housing heating oil which is used on-site
- Tanks where visual inspection is feasible
- Septic tanks
- Storm and wastewater systems
- Oil-water separators
- Emergency spill and overfill tanks
- Flow-through process tanks
All USTs used for diesel fuel storage as well as other flammable or hazardous liquids must meet certain design requirements in order to ensure the safety of the public and the environment.
Underground petrochemical fuel storage tanks must have corrosion protection for the tanks, all piping, and any metal components. USTs constructed of corrodible material must also have cathodic protection.
Types of Cathodic Protection
- Sacrificial Anode Systems – Tanks must be tested within six months of installation by qualified corrosion inspectors, at least every three year thereafter, and six months after any repairs have been made to the system.
- Impressed Current Systems – Impressed current rectifier must be tested a minimum of every sixty days by facility personnel, and records of at least three readings must be kept.
Spillage and Overfill
Any UST receiving over 25 gallons of liquid at any one time is required to have spillage and overfill protection in place. Facilities with fuel storage tanks or other hazardous storage tanks must have spillage protection equipment for the prevention of liquid release when the fill pipe and transfer hose are disconnected.
Overspill equipment should be inspected regularly to ensure water tightness. It should be kept free of debris and liquids.
Overspill equipment should
- Automatically shut off liquid flow when tank is at 95% capacity
- Have a high-level alarm or flow gauge alerting the filling operator when tanks reach 90% capacity
- Restrict flow 30 minutes before overfilling
- Have a high-level alarm to alert filling operator one minute prior to overfilling
- Automatically shut off to prevent product exposure to tank-top fittings
UST systems must have one or more methods of detection for leakages from any part of the tank. Any method installed must have a probability of detection of 0.95 and a probability of false alarm of 0.05.
Acceptable Release Detection Methods
- Automatic tank gauging (ATG) systems
- Secondary containment with interstitial monitoring
- Vapor monitoring
- Groundwater monitoring
Aboveground Storage Tanks
Many companies are moving to aboveground fuel storage tanks (ASTs) for flammable or toxic liquids. ASTs are quicker, easier, and more cost effective to install as well as easier to inspect, maintain, and repair.
Most of the requirements for ASTs are the same as USTs. The advantage of ASTs is that implementation of these rules and regulations is much easier and more cost effective.
ASTs and piping must be installed according to 40 CFR Part 112, NFPA 30 (Section 2.2), 29 CFR Part 1910, American Petroleum Institute standards. In addition, most states have fire codes, technical standards, permit requirements, and other provisions in place to regulate ASTs. The most common provisions are secondary containment, volume capacity, release, corrosion, and overfill protection, and piping and valve standards. Chapters two and three of NFPA 30 include the following requirements for ASTs holding more than 660 gallons:
- Location and spacing must be in compliance with NFPA 30
- ASTs should be stored in a cool, dry place well away from excessive heat and open flames or flammable substances
- Liquefied propane gas (LPG) containers must be a minimum of 20 feet away from flammable or combustible liquid storage tanks
- Volume of diked area must be equal to or greater than the capacity of the largest tank within the diked area and should meet other NFPA 30 requirements
Spill Prevention and Control
Facilities meeting the criteria of 40 CFR Part 112 must evaluate the potential spill risks associated with storing petrochemicals and other hazardous substances and must assess the magnitude of these risks. Facilities must comply with the spill prevention control and countermeasures (SPCC) requirements if:
- The facility is a non-transportation fixed facility which could expect to discharge oil into or upon navigable waters of the U.S. or adjoining shorelines.
- The facility has a total aboveground oil storage capacity of more than 1,320 gallons.
Design and Operations for Spill Prevention
Spill Risk Determination
Potential spill risks are associated with aboveground fuel storage tanks as well as underground fuel storage tanks. An accurate inventory of a tank’s spill risks must be documented. This includes the tank area, size, volume, storage capacity, contents, and function. A facility layout must be prepared identifying the spill risk areas and probable dispersion pathways, topography, facility boundaries, and all buildings and structures. The layout must included preventive systems, sources of water for fire fighting, and service and emergency facilities relative to the spill risk areas.
Spill prevention and control requires proper implementation of a risk assessment of the type of material storage, its quantity and type, and the incompatible surrounding storage conditions. Evaluation of the number of possible releases, what impact the release would have given potential exposure path, direction and rate of flow, and the sensitive environmental areas and natural resources surrounding the storage area and facility should be performed for risk mitigation. Sensitive environmental areas can include:
- Park areas
- Wildlife Sanctuaries
- Agricultural areas
Bulk fuel storage tanks must be compatible with the fuel stored and provide secondary containment for the entire contents of the largest tank plus freeboard for precipitation. For most ASTs secondary containment is an outer steel wall encasing an inner steel wall. Tanks must also have:
- High-liquid-level alarms with pump
- 40 CFR compliant liquid level sensors and gauges
Security measures for tanks must follow the provisions of 40 CFR §112.7(g). These provisions include:
- Locking entrance gates
- Locking valves and pump controls
- Transfer points – capped, locked, and marked
- Adequate lighting for night time visibility
Aboveground fuel storage tank pipelines must be properly located to allow regular integrity and leakage inspections. Abrasion and corrosion and allowances for expansion and contraction must be avoided for all pipe supports. Newly installed or replacement buried piping must have be wrapped and coated. Pipelines that are out of service for an extended period of time must be capped or blank flanged at the terminal connection design of the transfer point and the origin must be marked.