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CF-West Service-CS 881215Staff Requirements: .... ub- £otal: .,,,.` Position "~;,rc&o,r .. ~ ~b~;c ~o~r:'.'": I · .:'~ t( , ' Time'vF;T,E, Io~ Io~ I Ok,'s Requirements of Others: TOq~AL: (_.oat. Materials/Eqpt,: .~_aff Labor: $ s 40'k s Other: TOTAL: GRAND TOTAL: $ $ TIME: Removal and Disposal of Used Underground Petroleum Storage Tanks SECTION 1--GENERAL 1.1 Introduction Underground petroleum storage systems that are no longer needed or suitable for product storage must be properly disposed in place or removed in order to avoid future safety or environmental 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 per- sonnel involved in the procedures outlined in this recommended practice should be familiar with the potential hazards, and be knowledgeable in the appro- priate 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 disposal in place, removal, storage, and off-site disposal of underground storage tank systems that have contained flammable or combustible fluids. In general, it outlines requirements, procedures, and operating con- ditions to be followed by contractors, engineers, or other individuals who may be involved in i'hese practices. While this recommended practice specifically addresses underground petroleum storage tank systems at service station facilities, the principles outlined may be applied to similar systems used at other petroleum storage facili- ties. All such work must be accomplished in accordance with federal, state, and local requirements as well as accepted safety standards. Before initiating work, the appropriate government agencies should be consulted concerning applicable regulatory and permit require- ments. 1.2.2 All applicable permits must be obtained prior to beginning any work. Where required, contractors must be approved by local authorities. Contractors, sub- contractors, and their employees responsible for tank abandonment or removal should be familiar with: (a) all applicable safety rules and regulations, (b) the use of equipment and procedures for testing and vapor-freeing tanks, (c) the handling and disposal of the types of wastes likely to be encountered, and (d) the applicable sections of the publications referenced in 1.4. 1.2.3 The procedures outlined in this recommended practice can be carried out without the need to enter the tank. Should tank entry be desired, the procedures outlined in API Publications 2015, 2015A, and 2217 and Recommended Practice 1631 should be followed. 1.3 Special Precautions During the course of underground storage tank removal or in place disposal, workers may be exposed to petroleum hydrocarbon liquids, vapors, or wastes. The precautions in 1.3.1 and 1.3.2 should be observed by all individuals engaged in the procedures discussed in this recommended practice. 1.3.1 TOXICITY CONSIDERATIONS: PETROLEUM SUBSTANCES Users should be aware of appropriate health precau- tions. When high concentrations of petroleum hydro- carbon vapors are inhaled, symptoms of intoxication may result. These symptoms, ranging from simple dizzi- ness to excitement or unconsciousness, are similar to those produced by alcohol or anesthetic gases. If such effects occur, the individual should be removed to fresh air. For minor effects of exposure, breathing fresh air or oxygen results in rapid recovery. If breathing has stop- ped, artificial respiration should be applied promptly. Medical attention should be obtained as soon as possi- ble. Paragraphs 1.3.1.1 and 1.3.1.2 contain special toxicity considerations for benzene and tetraethyl lead, which may be present in petroleum products or wastes found in underground storage tanks. Care should be ex- ercised to minimize exposure to these substances when they are present during the handling of used under- ground petroleum storage tanks. WARNING: Tests have shown that prolonged or repeated exposure to some petroleum substances, in liquid or vapor form, may cause serious illness, in- cluding cancer, in laboratory animals. Although the significance of these test results to human health is not fully understood, exposure to petroleum substances should be minimized. The following health precautions are suggested: a. Avoid skin contact and inhaling vapors. APl RECOMMENDED PRACTICE 1604 b. Keep petroleum liquids away from eyes, skin, and mouth; they can be harmful or fatal if inhaled, absorbed through the skin, or ingested. c. Use soap and water or waterless hand cleaner to remove any petroleum product that contacts skin. Do not use gasoline or similar solvents to remove oil and grease from skin. d. Promptly wash petroleum-soaked clothes and avoid using soaked leather goods. Properly dispose of rags. e. Keep work areas clean and well ventilated. f. Clean up spills promptly. 1.3.1.1 Benzene High occupational exposures to benzene have been associated with various human blood disorders, in- cluding 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 American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) for benzene is 1-part-per-million time-weighted average, with a short term exposure limit of 25 parts-per-million (the latter is designated for deletion in 1986 or 1987). The Occupa- tional Safety and Health Administration (OSHA) 8-hour time-weighted average for benzene is 10 parts- per-million with an acceptable ceiling concentration of 25 parts-per-million and an acceptable peak of 50 parts- per-million for 10 minutes (29 CFR 1910.1000, Table Z-2). OSHA conducted a rulemaking in 1986 with the intent to revise this standard. The latest OSHA Occupa- tional Safety and Health Standards should be consulted to determine the current TLV. 1.3.1.2 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 milligrams per cubic meter for general room air. The TLV in OSHA's Occupational Safety and Health Standards (29 CFR 1910.1000, Table Z-l) is 0.075 milligrams per cubic meter. 1.3.2 FLAMMABILITY AND COMBUSTIBILITY CONSIDERATIONS 1.3.2.1 Flammable or combustible vapors are likely to be present in the work area. The concentration of vapors in the tank, t,he excavation, or the work area may reach the flammable (explosive) range before venting is completed and a safe atmosphere is reached. Therefore, precautions must be taken to: (a) eliminate all potential sources of ignition from the area (for example, smoking materials, nonexplosion-proof electrical and internal combustion equipment), (b) prevent the discharge of static electricity during venting of flammable vapors, and (c) prevent the accumulation of vapors at ground level. Refer to API Publication 2015 and Recommended Practice 2003 for general precautionary measures to follow during the vapor-freeing procedure. 1.3.2.2 A combustible gas indicator (CGI) should be used to check for hazardous vapor concentrations (see 4.3). All open flame and spark-producing equipment within the vapor hazard area should be shut down. Elec- trical equipment (for example, pumps and portable hand tools) used in the area must be explosion-proof in accordance with NFPA 70B Class I, Division I, Group D or otherwise approved for use in potentially explosive atmospheres. 1.4 Referenced Publications Portions of the following documents contain infor- mation regarding various engineering and safety pro- cedtires that may be applicable to underground storage tank removal or disposal. API Bull 1628 RP 1631 RP 2003 Publ 2015 Publ 2015A Publ 2217 Publ 2219 Underground Spill Cleanup Manual Interior Lining of Underground Stor- age Tanks Protection Against Ignitions Arising Out of Static, Lightning, and Stray Currents Cleaning Petroleum Storage Tanks A Guide for Controlling the Lead Hazard Associated with Tank Entry and Cleaning (Supplement to API Publ 2015) Guidelines for Confined Space Work in the Petroleum Industry Safe Operating Guidelines for Vacu- um Trucks in Petroleum Service NFPA~ 327 70B Standard Procedure for Cleaning or Safeguarding Small Tanks and Con- tainers Electrical Equipment Maintenance lNational Fire Protection Association, Batterymarch Park, Quincy, Massachusetts 02269. REMOVAL AND DISPOSAL OF USED UNDERGROUND PETROLEUM STORAGE TANKS OSHA2 Occupational Safety and Health Standards (29 CFR 1910.1000) EPA3 General Regulations for Ha;:ardous Waste Manage- ment (40 CFR 260) Regulations for Identifying Hazardous Waste (40 CFR 261) Regulations for Hazardous Waste Generators (40 CFR 262) Underground Storage Tanks Regulations (40 CFR 280.11,280.22) SECTION 2--TEMPORARILY OUT OF SERVICE. 2.1 Applicability Underground petroleum storage tank systems are considered temporarily out of service if they are: (a) idle but will be returned to service within one year, (b) are awaiting abandonment in place, or (c) are awaiting removal. 2.2 Securing Tank Systems Tanks temporarily out of service must be properly secured for the period they will be out of service. Tanks may be considered properly secured if processed as follows: a. Observe all special precautions described in 1.3 through 1.3.2.2. b. Remove stored product from the tank using one of the following methods: 1. Drain all product lines into the tank, then remove all liquids from the tank. 2. Remove all flammable or combustible liquids with the exception of a sufficient quantity (approxi- mately four inches) to assure a saturated vapor space. 3. When high water table or flooding conditions exist, remove all stored liquid and ballast the tank by filling with water. c. Cap the fill pipe, gauge pipe, tank truck vapor recovery fitting, and vapor return. Secure the tank against tampering. d. Cap the product lines at the service station island, or elsewhere if the pumps are removed, or leave the pumps connected and locked. Disconnect electric power to the pumps. e. Leave the vent line open. f. Consult the appropriate local, state, or federal agen- cies concerning regulatory notifi6ation requirements. SECTION 3--DISPOSAL IN PLACE 3.1 Criteria for Disposal in Place 3.1.1 This section describes a safe method for the in place disposal of underground tanks. Removal of the tank is preferred (see Section 4). Disposal of the tank in place should be considered in the following cir- cumstances: (a) because of the tank location adjacent equipment or structures may be damaged or weakened if the tank is removed, (b) removal may be physically impossible, or (c) removal may incur excessive costs. A determination of whether to dispose of a tank in place or to remove it will depend upon: (a) local regulations which may prohibit abandonment in place, (b) the loca- tion of the facility and tank, (c) the availability of equip- ment, and (d) cost. Additional considerations include the length of service the equipment has provided and its reuse or salvage value. 3.1.2 The federal Resource Conservation and Recovery Act (RCRA) (40 CFR 260-265) places restric- tions on disposal of certain residues that may be present in some underground storage tanks'. Residues from tanks that have held leaded gasoline should be treated with extreme caution. Lead compounds and other resi- dues in the tank may be classified as hazardous wastes. All liquids and residues removed from the tank should be handled in accordance with appropriate federal, state, and local regulations. Product removed from the tank can usually be reused or recycled. 2Occupational Safety and Health Administration, U.S. Department of Labor, Washington, D.C. 20402. 3U.S. Environmental Protection Agency, 401 M Street, S.W., Washington, D.C. 20460. 3.2 Procedures for Disposal in Place 3.2.1 Tanks may be effectively and safely disposed in place by using the procedures in 3.2.2 through 3.2.11. APl RECOMMENDED PRACTICE 1604 3.2.2 Observe the special precautions described in 1.3 through 1.3.2.2. 3.2.3 Drain product piping into the tank, being care- ful to avoid any spillage to the excavation area. Discon- nect product piping from the tank, and cap or remove the piping. 3.2.4 Remove liquids and residues from the tank by using explosion-proof or air-driven pumps. Pump motors and suction hoses must be bonded to the tank or otherwise grounded to prevent electrostatic ignition hazards. It may be necessary to use a hand pump to remove the last few inches of liquid from the bottom of the tank. If a vacuum truck is used for removal of liquids or residues, the area of operation for the vacuum truck must be vapor-free. The truck should be located upwind from the tank and outside the path of probable vapor travel. The vacuum pump exhaust gases should be discharged through a hose of adequate size and length downwind of the truck and tank area. See APl Publica- tion 2219 for vacuum truck operating and safety prac- tices. 3.2.5 Excavate to the top of the tank. 3.2.6 Remove the drop tube, fill pipe, gauge pipe, vapor recovery truck connection, submersible pumps, and other tank fixtures. Cap or remove all non-product lines, such as vapor recovery lines, except for the vent line. The vent line should remain connected until the tank is purged (see 4.2.2 through 4.2.7). Temporarily plug all other tank openings. 3.2.7 Purge the tank of flammable vapors. This may be accomplished using methods outlined in 4.2.2 through 4.2.7. Vent all vapors a minimum of 12 feet above grade and 3 feet above any adjacent roof lines. Monitor the tank for flammable vapor with a combusti- ble gas indicator until the tank atmosphere has been brought to less than 20 percent of the lower flammable limit (see 4.3). 3.2.8 One or more holes may be cut in the tank top if existing tank openings are not adequate for introduction of the inert material to be used to fill the tank. 3.2.9 Proceed to introduce a suitable solid inert material through openings in the top of the tank. It is important to fill the tank as full as possible with the sand or other inert material. The procedures in 3.2.9.1 through 3.2.9.3 are intended to minimize any surface settling subsequent to disposal of the tank in place. 3.2.9.1 Sand will flow readily and is generally availa- ble. Any kind of sand is suitable if it is free of rocks, which might limit leveling-out in the tank. The sand may be introduced dry as long as it flows in freely. When the sand cone nears the top of the tank, the sand can be washed into the tank with a nominal amount of water and puddled to cause it to. flow to the ends. The use of larger amounts of water should be avoided since the tank might be filled with water before it is filled with sand. 3.2.9.2 Almost complete filling of the tank can be achieved by using a combination of sand and earth. [*ill the tank with sand to approximately 80 percent of calculated capacity. Mix soil and water to make a free- flowing mud and pour the mixture into thc tank open- ing. Puddle the mixture until the tank is full and overflows the fill opening. 3.2.9.3 Other types of inert materials, slurries, or expandable materials such as polyurethane-type foams may be used when approved by regulatory officials. 3.2.10 After the tank is filled with an inert material, all tank openings should be plugged or capped unless it was necessary to cut open the tank top (see 3.2.8). 3.2.11 Disconnect and cap or remove the vent line. 3.3 Recordkeeping 3.3.1 When underground tanks are disposed in place, the owner of the tank should keep a permanent record of the tank location, the date of disposal in place, and the method of conditioning the tank for disposal. All local, state, and federal regulatory requirements for tank disposal/closure and notification must be ob- served. 3.3.2 It is recommended that the tank owner inform a potential buyer of the presence of abandoned under- ground tanks when properties are sold. A property owner should also be informed at the termination of the property lease. In some areas this may be a regulatory requirement. It may be desirable to obtain an acknowl- edgement or a release from the property owner. REMOVAL AND DISPOSAL OF USED UNDERGROUND PETROLEUM STORAGE TANKS SECTION 4--REMOVAL OF UNDERGROUND TANKS 4.1 Preparation 4.1.1 Observe the special safety precautions in 1.3 through 1.3.2.2. 4.1.2 Drain product piping into the tank, being careful to avoid any spillage. Cap or remove product piping. 4.1.3 Remove residues and liquids from the tank as described in 3.2.4. Also observe the restrictions in 3.1.2. 4.1.4 Excava~te to the top of tank. 4.1.5 Remove the fill pipe, gauge pipe, vapor recovery truck connection, submersible pumps, and other tank fixtures. Remove the drop tube, except when it is planned to vapor-free the tank by using an eductor as in 4.2.5. Cap or remove all non-product lines, such as vapor recovery lines, except the vent line. The vent line should remain connected until the tank is purged. Tem- porarily plug all other tank openings so that all vapors will exit through the vent line during the vapor-freeing process. 4.2 Purging 4.2.1 Remove flammable vapors by one of the methods described in 4.2.2 through 4.2.7, or as required by local codes. These methods provide a means for tem- porary vapor-freeing of the tank atmosphere. However, it is important to recognize that the tank may continue to be a source of flammable vapors even after following the vapor-freeing procedures described in 4.2.2 through 4.2.7. For this reason, caution must always be exercised when handling or working around tanks that have stored flammable or combustible liquids. Before in- itiating work in the tank area or on the tank, a com- bustible gas indicator should be used to assess vapor concentrations in the tank and work area. 4.2.2 Vent all vapors from the tank at a minimum height of 12 feet above grade and 3 feet above any adja- cent roof lines until the tank is purged of flammable vapors. The work area should be free from sources of ignition (see 1.3.2). 4.2.3 Flammable and combustible vapors may be purged with an inert gas such as carbon dioxide (COz) or nitrogen (NZ). This method should not be utilized if the tank is to be entered for any reason, as 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 Iow pressure to avoid the generation of static electricity. When using CO2 or N2, pressures in the tank should not exceed 5 pounds per square inch gauge. CAUTION: The process of introducing compressed gases into the tank may create a potential ignition hazard as the result of the development of static elec- trical charges. The discharging device must therefore be grounded. Explosions have resulted from the discharg- ing of CO2 fire extinguishers into tanks containing a flammable vapor-air mixture. CO2 extinguishers should not be used for inerting flammable atmospheres. 4.2.4 If the method described in 4.2.3 is not practical, the vapors in the tank may be displaced by adding solid carbon dioxide (dry ice) to the tank in the amount of at least 1.5 pounds per 100 gallons of tank capacity. The dry ice should be crushed and distributed evenly over the greatest possible area in the tank to promote rapid evaporation. As the dry ice vaporizes, flammable vapors will flow out of the tank and may surround the area. Therefore, where practical, plug all tank openings except the vent after introducing the solid CO2 and con- tinue to observe all normal safety precautions regarding flammable or combustible vapors. Make sure that all of the dry ice has evaporated before proceeding. CAUTION: Skin contact with dry ice may produce burns. 4.2.5 Flammable vapors may be exhausted from the tank by one of two methods of tank ventilation listed below: a. Ventilation using an eductor-type air mover usually driven by compressed air is illustrated in Figure 1. The eductor-type air mover must be properly bonded to pre- vent the generation and discharge of static electricity. When using this method, the fill (drop) tube should remain in place to ensure ventilation at the bottom of the tank. Tanks equipped with fill (drop) tubes that are not removable should be purged by this method. An eductor extension shall be used to discharge vapors a minimum of 12 feet above grade. b. Ventilation with a diffused air bl'ower is illustrated in Figure 2. When using this purging method, it is im- perative that the air-diffusing pipe is properly bonded to prevent the discharge of a spark. Fill (drop) tubes must be removed to allow proper diffusion of the air in the tank. Air supply should be from a compressor that has been checked to ensure a clean air supply and is free APl RECOMMENDED PRACTICE 1604 Eductor type (See detail lA) /~i Air flow Fill (drop) tube [[ Air flow Ed/U~pressed air Detail lA Figure 1--Eductor-Type Air Mover Diffused air blower (See detail 2A) Ground cable (See note) 5 pslg ~ ~ flow f 4" to first hole Pipe must touch tank bottom for ground Brass pipe 11/2" dia. with four rows of 35 -- %" holes (140 holes total) Quick cou Pressure reducing valve with gauge valve Hose to air compressor Detail 2A Note: Ground cable brazed to pipe must be clamped to fill pipe. Use 12 gauge ground wire from fill pipe to water pipe or ground rod. Figure 2--Diffused Air Blower REMOVAL AND DISPOSAL OF USED UNDERGROUND PETROLEUM STORAGE TANKS from volatile vapors. Air pressure in the tank must not exceed 5 pounds per square inch gauge. 4.2.6 One of the safest and simplest methods for vapor-freeing a tank is to fill the tank with water. However, in certain areas, regulatory requirements for treatment/disposal of water used in the vapor-freeing process may make this method cost-prohibitive. Before employing the method described in 4.2.6.1 through 4.2.6.3, consult local regulations. 4.2.6.1 Fill the tank with water until the floating product nears the fill opening. Remove the floating product and place it in a suitable container for proper disposal. Care should be exercised to ensure that neither product nor water is spilled into the tank excavation. 4.2.6.2 In the process of filling the tank with water, flammable vapors will be expelled through both the vent and fill openings, but primarily at the fill opening. Nor- mal safety precautions should be observed. To minimize this escape of vapor through the fill opening, the open- ing may be temporarily capped. 4.2.6.3 When the tank is free of vapor, pump out the water and dispose of it in accordance with local regula- tions. 4.2.7 Steam can be used to clean and vapor-free a tank. However, a large static charge can build up on the nozzle of the steam jet. Insulated objects on which the steam impinges can also become charged. If steam is to be used for either purging or cleaning a tank or other equipment, the steam discharge nozzle and all conduc- tive insulated objects subject to impingement or conden- sation should be bonded to the tank or be grounded. Steam purging of tanks should be avoided when suitable alternatives are available. Further reference to steam cleaning of tanks is found in NFPA 327. 4.3 Testing 4.3.1 The tank atmosphere and the excavation area should be regularly tested for flammable or combustible vapor concentrations until the tank is removed from both the excavation and the site. Such tests are to be made with a combustible gas indicator which is properly calibrated according to the manufacturer's instructions (typically on pentane or hexane in air), and which is thoroughly checked and maintained in accordance with the manufacturer's instructions. Persons responsible for testing must be completely familiar with the use of the instrument and the interpretation of the instrument's readings. 4.3.2 The tank vapor space is to be tested by plsicing the combustible gas indicator probe into the fill opening with the drop tube removed. Readings should be taken at the bottom, middle, and upper portions of the tank, and the instrument should be cleared after each reading. If the tank is equipped with a non-removable fill tube, readings should be taken through another opening. Liquid product must not enter the probe. Readings of 20 percent or less of the lower flammable limit must be obtained before the tank is considered safe for removal from the ground. 4.3.3 Combustible gas indicator readings may be misleading where the tank atmosphere contains less than 5 percent by volume oxygen, as in a tank vapor- freed with COe, Ne, or another inert gas. In general, readings in oxygen-deficient atmospheres will be on the high, or safe, side. It may be desirable to use an oxygen indicator to assess the oxygen concentration. 4.4 Removal 4.4.1 After the tank has been freed of vapors and before it is removed from the excavation, plug or cap all accessible holes. One plug should have a 1/8-inch vent hole to prevent the tank from being subjected to ex- cessive differential pressure caused by temperature changes. The tank should always be positioned with this vent plug on top of the tank during subsequent trans- port and storage. 4.4.2 Excavate around the tank to uncover it for removal. Remove the tank from the excavation and place it on a level surface. Use wood blocks to prevent movement of the tank after removal and prior to loading on a truck for transportation. Use screwed (boiler) plugs to plug any corrosion holes in the tank shell. 4.4.3 When partially or totally removing an existing underground storage system, a small amount of con- taminated backfill may be encountered. The contamina- tion can be due to minor spills and drips during previous operation of the facility or from drips and minor spills that may occur during removal. Contaminated backfill may be a potential safety and environmental hazard. Spills or drips should be contained to minimize con- tamination during removal. If contamination is severe, consult local environmental officials, the fire marshal, or the USEPA for assistance and requirements. See API Bulletin 1628 for further information. 4.4.4 Tanks should be labeled after removal from the ground but prior to removal from the site. Regardless of the condition of the tank, the label should contain a APl RECOMMENDED PRACTICE 1604 warning against certain types of reuse. The former con- tents and present vapor state of each tank, including vapor-freeing treatment and date should also be in- dicated. The label should be similar to the following in legible letters at least 2 inches high: TANK HAS CONTAINED LEADED GASOLINE* NOT VAPOR FREE NOT SUITABLE FOR STORAGE OF FOOD OR LIQUIDS INTENDED FOR HUMAN OR ANIMAL CONSUMPTION DATE OF REMOVAL: MONTH/DAY/YEAR *Or other flammable/combustible liquid. Use the applicable designation, for example, DIESEL. 4.4.5 Tanks that have held leaded motor fuels (or whose service history is unknown) should also be clearly labeled with the following information (see API Publi- cation 2015A for additional guidelines): TANK HAS CONTAINED LEADED GASOLINE LEAD VAPORS MAY BE RELEASED IF HEAT IS APPLIED TO THE TANK SHELL 4.4.6 Tanks should be removed from the site as promptly as possible after vapor-freeing procedures have been completed, preferably on the day of tank removal from the excavation. If a tank remains at the site overnight or longer, additional vapor may be re- leased from any liquid absorbed in the tank walls or residues remaining in the tank. 4.4.6.1 Before the tank is removed from the site, the tank atmosphere should be checked with a combustible gas indicator as specified in 4.3 to ensure that it does not exceed 20 percent of the lower flammable limit. 4.4.6.2 The tank should be secured on a truck for transportation to the storage or disposal site with the 1/8-inch vent hole located at the uppermost point on the tank. Tanks should be transported in accordance with all applicable local, state, and federal regulations. SECTION 5--STORAGE OF USED TANKS 5.1 Storage Considerations Even though used tanks that have contained flam- mable or combustible liquids have been vapor-freed at one time, they cannot be guaranteed to remain vapor- free. Hydrocarbons may he retained in crevices and under scale and may be released when disturbed or over a period of time. It is important, therefore, that ap- propriate safety precautions be observed at all times. 5.2 Storage Procedures 5.2.1 Tanks should be vapor-freed before being plac- ed in storage (see 4.2). Tanks should also be free of all liquids and residues. All tank openings should be tightly plugged or capped, with one plug having a 1/8-inch vent hole to prevent the tank from being subjected to ex- cessive differential pressure caused by temperature changes. Tanks should be stored with the vented plug at the highest point on the tank. All tanks should be labeled as described in 4.4.4 and 4.4.5. 5.2.2 Used tanks should be stored in secure areas on the premises of persons familiar with any attendant hazards and where the general public will not have access. A fenced yard, apart from other facilities, is desirable. SECTION 6--SALE FOR REUSE 6.1 Considerations for Reuse Careful consideration should be given to the reuse of tanks that have been in petroleum storage service. If a tank is sold for reuse, the purchaser should be given a very clear understanding of the former use and present condition of the tank. The seller of a tank to be returned to service in an underground petroleum storage system must inform the purchaser of the tank of the owner's notification requirements under applicable federal regulations (40 CFR 280.11 and 40 CFR 280.22)i There may also be similar state or local regulations. Buyers of such tanks should check with the original manufacturer of the tank to determine its suitability for reuse. It is ad- visable to test the tanks for flammable vapors (see 4.3) before they are transported. CA UTION: Tanks that previously contained gasoline must not be used for the subsequent storage of food or liquids intended for animal or human consumption. REMOVAL AND DISPOSAL OF USED UNDERGROUND PETROLEUM STORAGE TANKS 6.2 Conditions of Sale A bill of sale should be used to transfer tank owner- ship. The bill of sale should include the purchaser's acknowledgement that he assumes all liability related to the tank. Bills of sale should indicate the former use of the tank and carry the following warning regardless of the former contents of the tank: TANK HAS CONTAINED LEADED GASOLINE* NOT VAPOR FREE NOT SUITABLE FOR STORAGE OF FOOD OR LIQUIDS INTENDED FOR HUMAN OR ANIMAL CONSUMPTION *Or other flammable/combustible liquid. Use the applicable designation, for example, DIESEL. SECTION 7--DISPOSAL 7.1 Disposal Criteria 7.1.1 Tanks should be disposed of when they are no longer fit for the storage of flammable or combustible liquids or any other appropriate use. Whether sold to a scrap dealer or disposed of at an acceptable facility, suf- ficient holes should be made in the tanks to render them unfit for further use. 7.1.2 Tanks that have been lined internally or coated externally with epoxy-based or similar materials may not be accepted by scrap processors. Prior inquiries should be made as to the requirements of the processor accepting the tank for scrap. 7.2 Disposal Procedures 7.2.1 After a tank has been vapor-freed, it should be rendered unsuitable for future use as a storage tank by puncturing, cutting, or drilling numerous holes in all sections of the tank. 7.2.2 All tanks should be labeled as described in 4.4.4 and 4.4.5. 7.2.3 A bill of sale should be used to transfer tank ownership (see 6.2). 7.2.4 Prior to disposal of used tanks, current federal, state, and local regulations should be checked to deter- mine if special procedures or preparations are required.