API RP 1604-2010 pdf download.Closure of Underground Petroleum Storage Tanks.
1.1 Introduction Underground petroleum storage systems that are no longer needed or suitable for product storage, or are not in compli- ance with applicable regulations and are not brought into compliance by upgrading or replacing, must be properly closed in place or removed to avoid future safety or environ- mental hazards. Because of the nature of the flammable or combustible liquids that are stored in these tanks, hazardous conditions may arise in the work area during disposal in place or removal and subsequent handling of tanks. For this reason, all personnel involved in the procedures outlined in this rec- ommended practice should be familiar with the potential haz- ards, and be knowledgeable in the appropriate health and safety measures needed to ensure a safe working environment. 1.2 Scope and Purpose 1.2.1 This publication recommends procedures for the closure in place, removal, storage, and off- site disposal of underground storage tank systems that have contained flammable or combustible fluids. In general, it outines re- quirements, procedures, and operating conditions to be fol- lowed by contractors, engineers, and other individuals who may be involved in these practices. While this recommended practice specifically addresses underground petroleum stor- age tank systems at service station facilities, the principles outlined may be applied to similar systems used at other petroleum storage facilities. All such work must be accom- plished in accordance with federal, state, and local require- ments as well as accepted safety standards. Before initiating work, the appropriate government agen- cies should be notified and consulted concerning applicable regulatory and permit requirements.
220.127.116.11 Benzene High occupational exposures to benzene have been associated with various human blood disorders, including an increased risk of leukemia. Very high levels have also been known to affect the central nervous system.. Benzene administered by mouth has induced cancer in laboratory animals in long- term tests. Benzene is rapidly absorbed through the skin. The Occupational Safety and Health Administration (OSHA) imposes limits on occupational exposure and requirements concerning the communication of hazards to workers. See 29 Code of Federal Regulations Parts 1919.1000 (Table A-2), 1910.1028, and 1910.1200. 18.104.22.168 Tetraethyl Lead This organic form of lead can cause diseases of the central and peripheral nervous system, the kidney and the blood. Skin absorption of this compound is a major route of entry into the body. The ACGIH time weighted average is 0.1 mil- ligrams per cubic meter for general room air. The TLV in OSHA’s Occupational Safety and Health Standards (29 Code of Federal Regulations Part 1910.1000, Table Z-1) is 0.075 milligrams per cubic meter. 1.3.2 FLAMMABILITY AND COMBUSTIBILITY CONSIDERATIONS 22.214.171.124 Flammable or combustible vapors are likely to be present in the work area. The concentration of vapors in the tank, the excavation, or the work area may reach the flamma- ble or explosive range before venting is complete and a safe atmosphere is reached. Therefore, the following precautions must be taken: a. Eliminate all potential sources of ignition from the area (for example, smoking materials, and nonexplosion-proof electrical and internal combustion equipment). b. Prevent the discharge of static electricity during venting of flammable vapors.
4.3 Purging and Inerting 4.3.1 Purging is the removal of flammable vapors from a tank to deprive a potential fire of any source of fuel. Inerting is the displacement of oxygen from a tank (and the incidental removal of some vapors) to deprive a potential fire of a source of oxygen. A tank may be inerted by one of the methods described in 4.3.3 or 4.3.4. A tank may be purged by one of the methods described in 4.3.5, 4.3.6, or 4.3.7. A tank may continue to be a source of flammable vapors even after following one of these procedures. Therefore, caution must always be exercised when handling or working around tanks that have stored flammable or combustible liquids. Immediately before initiating work in the tank area or on the tank, a combustible gas indicator should be used to assess vapor concentrations in the tank and work area. 4.3.2 Both purging and inerting cause the displacement of vapors from the tank. All vapors should be vented from the tank at a minimum height of 12 feet above grade and 3 feet above any adjacent roof lines. The work area should be free from sources of ignition (see 1.3.2). Appropriate local, state, or federal agencies should be consulted concerning regulatory requirements for air discharges. 4.3.3 A tank may be inerted with an inert gas such as carbon dioxide (CO2) or nitrogen (N2). This method should not be used if the tank is to be entered for any reason, since the tank atmosphere will be oxygen deficient. The inert gas should be introduced through a single tank opening at a point near the bottom of the tank at the end of the tank opposite the vent. When inert gases are used, they should be introduced under low pressure to avoid the generation of static electric- ity. When using CO2 or N2, pressures in the tank should not exceed 5 pounds per square inch gauge.