Code of Maine Rules › 06 - DEPARTMENT OF ENVIRONMENTAL PROTECTION › 096 - DEPARTMENT OF ENVIRONMENTAL PROTECTION - GENERAL › Chapter 691 - RULE FOR UNDERGROUND OIL STORAGE FACILITIES › Appendix 096-691-K - Requirements for Abandonment of Underground Oil Storage Facilities by Filling in Place

Current through 2024-29, July 17, 2024
1. Piping must be drained and flushed into the tank.
2. All liquid that can be pumped out, including that liquid
				  requiring a hand pump to remove, must be removed and any liquids that cannot be
				  used for their originally intended purpose must be disposed of in accordance
				  with the Department's
Waste Oil Management Rules
, 06-096
				  C.M.R. ch. 860. UL approved explosion proof equipment must be used to remove
				  Class I tanks that may still contain product. Flammable vapors from a vacuum
				  truck removing oil from a tank or facility must be vented at least 12 feet
				  above the ground surface, effective September 28, 1991. All sludge will also be
				  removed, handled, stored and disposed of in accordance with 06-096 C.M.R. ch.
				  851 of the Department's hazardous waste rules. Where it can be demonstrated to
				  Department satisfaction that a sludge is not a hazardous waste, it may be
				  disposed at a solid waste disposal facility licensed for such wastes.
3. The top of the tank must be exposed.
4. The fill (drop) tube must be removed. Fill, gauge, and
				  product lines must be disconnected. Open ends of all lines, except the vent
				  line, must be capped or plugged.
NOTE: Due to the potential of waste oil tank explosions, the
				  Department strongly recommends treating all waste oil tanks as a Class I liquid
				  tank except where testing shows the internal atmosphere not to be
				  explosive.
5. All tanks that contained Class I liquids must be made safe
				  prior to removing the tank from the ground by using one of the following
				  methods:
A. The tank can be inerted with dry ice in the amount of 1.5
				  pounds per 100 gallons of tank capacity. Dry ice shall be crushed and
				  distributed evenly over the greatest possible area. During the inerting
				  process, all necessary precautions to prevent ignition in the entire area must
				  be taken.
B. The tank can be inerted using nitrogen or another inert
				  gas approved by the Commissioner, introduced at low pressure at the bottom of
				  the tank. Inerting is considered complete when oxygen levels in the tank are
				  measured at less than 6 percent.
C. The tank can be considered inert if the tank atmosphere is
				  found to be oxygen deficient as defined by an oxygen reading of less than 6
				  percent.
D. The tank can be rendered vapor free by air purging in
				  accordance with API 1604. Air purging is considered complete when an
				  explosimeter indicates an atmosphere inside the tank of less than 10 percent of
				  the LEL while an oxygen meter indicates greater than 14 percent oxygen. Air
				  purging using air-moving equipment found on a vacuum truck is not
				  allowed.
During any of the above inerting, purging or removal
				  procedures, all necessary precautions to prevent ignition in the entire area
				  shall be taken, including but not limited to: grounding and bonding of
				  equipment; the use of explosion proof or intrinsically safe equipment; ambient
				  air monitoring of the surrounding area; and pedestrian and traffic control. All
				  weather and ambient atmospheric conditions must be evaluated prior to inerting
				  or purging, including, but not limited to, air exchange, wind direction, and
				  high humidity. All air monitoring instruments must be calibrated according to
				  the manufacturer's specifications. Measurements with air monitoring instruments
				  must be taken at the following points: one foot from the bottom of the tank; at
				  its lowest end; the middle of the tank's diameter; and at the tank
				  opening.
6. Vapors from the tank must be vented at least 12 feet above
				  the ground surface.
7. A suitable, solid, inert material must be introduced
				  through the hole in the top of the tank. The following materials are suitable
				  for this purpose:
A. Sand. Sand that is free of rocks is suitable for filling.
				  It may be poured dry as long as it flows freely. When the tank is nearly full,
				  sand should be washed into the tank with a nominal amount of water and puddled
				  to cause the sand to flow to the tank ends. The use of large amounts of water
				  must be avoided.
B. Sand and Earth Fill. The tank can be (1) filled with sand
				  to about 80 percent of the calculated capacity, and (2) filled to overflowing
				  for the remaining capacity using a mixture of soil and water in a free-flowing
				  mud.
C. Cement or mortar.