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0- 4 AN 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 fast 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 API Publica- tion 2219 for vacuum truck operating and safety prac- tices. 3.2.5 Excavate to the top of the tank. 3.2.8 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 avada. 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. Fill 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 the 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. DIM