Section 215.124  External Floating Roofs

a)         In addition to meeting the requirements of Section 215.123(b), no owner or operator of a stationary storage tank equipped with an external floating roof shall cause or allow the storage of any volatile petroleum liquid in the tank unless:

1)         The tank has been fitted with a continuous secondary seal extending from the floating roof to the tank wall (rim mounted secondary seal) or any other device which controls volatile organic material emissions with an effectiveness equal to or greater than a rimmounted secondary seal;

2)         Each seal closure device meets the following requirements:

A)        The seal is intact and uniformly in place around the circumference of the floating roof between the floating roof and tank wall; and

B)        The accumulated area of gaps exceeding 0.32 centimeter (1/8 inch) in width between the secondary seal and the tank wall shall not exceed 21.2 square centimeters per meter of tank diameter (1.0 square inches per foot of tank diameter).

3)         Emergency roof drains are provided with slotted membrane fabric covers or equivalent covers across at least 90 percent of the area of the opening;

4)         Openings are equipped with projections into the tank which remain below the liquid surface at all times;

5)         Inspections are conducted prior to May 1 of each year to insure compliance with subsection (a);

6)         The secondary seal gap is measured prior to May 1 of each year;

7)         Records of the types of volatile petroleum liquid stored, the maximum true vapor pressure of the liquid as stored, the results of the inspections and the results of the secondary seal gap measurements are maintained and available to the Agency, upon verbal or written request, at any reasonable time for a minimum of two years after the date on which the record was made.

b)         Subsection (a) does not apply to any stationary storage tank equipped with an external floating roof:

1)         Exempted under Section 215.123(a)(2) through 215.123(a)(6);

2)         Of welded construction equipped with a metallic-type shoe seal having a secondary seal from the top of the shoe seal to the tank wall (shoe-mounted secondary seal);

3)         Of welded construction equipped with a metallic-type shoe seal, a liquid-mounted foam seal, or a liquid-mounted liquid-filled-type seal, or other closure device of equivalent control efficiency approved by the Agency in which a petroleum liquid with a true vapor pressure less than 27.6 kPa (4.0 psia) at 294.3º K (70º F) is stored; or

4)         Used to store crude oil.

(Source:  Amended at 14 Ill. Reg. 9173, effective May 23, 1990)