WAC 296-826-30055   Installation.  

     You must:

     • Support tanks on noncombustible foundations designed for the type of tank.

     • Provide protection against flotation or other water damage, where high floodwater might occur.

     • Prevent the effects of freezing and consequent frost heaving, in tanks used for product storage at less than 32°F, by providing either support or heat supply.

     • Prevent accidental discharge of liquids from spreading into uncontrolled areas by providing, to the area surrounding a refrigerated tank or group of tanks, one of the following:

     – A drainage system provided with at least a one percent slope that terminates in an impounding basin with a capacity as large as the largest tank served;

     OR

     – A diked enclosure with a capacity as large as the largest tank served.

     • Meet, when using a diked enclosure or an impounding basin in a drainage system, the following requirements:

     – The wall is made of earth, steel, or concrete. If made of earth, meet both of the following:

     ▪ The top is flat and at least two feet wide;

     AND

     ▪ There is a stable slope consistent with the angle of the earth used

     – Design the wall to be both:

     ▪ Liquid tight;

     AND

     ▪ Able to withstand the hydrostatic pressure and the temperature.

     • Provide for drainage of rain water, that does not permit the release of ammonia, from diked or impounding areas.

Note:	• It is recommended that the ground in an impounding basin or within a diked enclosure be graded so that small spills or the early part of a large spill will accumulate at one side or corner contacting both:
	– A relatively small area of ground;
	AND
	– Exposing a relatively small surface area for heat gain.
	• Shallow channels in the ground surface or low curbs of earth can help guide the liquid to these low areas without contacting a large ground area.

[Statutory Authority: RCW 49.17.010, 49.17.040, 49.17.050, 49.17.060. 06-10-067, § 296-826-30055, filed 5/2/06, effective 9/1/06.]