Application tanks functionally connected to and dedicated solely for use with a fertigation operation may be exempt from the secondary and operational area containment rules (chapter 16-201 WAC). The following conditions determine whether a tank that is a component of a fertigation system is subject to the secondary and operational area containment rules.

(1) Time-in-place.

(a) Product can remain in an application tank for a period not to exceed nine consecutive months during an irrigation or application season. If the nine-month period is exceeded, the tank is deemed a storage facility and is therefore subject to the secondary and operational area containment rules.

(b) An application tank containing product during the nonapplication or nonirrigation season is subject to the secondary and operational area containment rules regardless of tank size.

(c) The application tank must be removed at the end of the irrigation or application season, whichever is shorter, but not to exceed nine months. At the end of this period, the application tank must be emptied, cleaned, visually inspected for integrity, and serviced. The tank must be removed from the site, or the tank must be decommissioned and clearly tagged with the words "out-of-service," or the tank must be managed as a permanent storage facility (chapter 16-201 WAC).

(2) Tank size.

(a) An application tank must have a rated capacity of six thousand five hundred gallons or less.

(b) An application tank with a rated capacity exceeding six thousand five hundred gallons is deemed a permanent storage facility.

(c) Multiple tanks positioned at an injection site with a cumulative capacity exceeding ten thousand gallons are also deemed a permanent fertilizer storage facility.

(d) Cumulative tank capacity cannot exceed ten thousand gallons per application system.

(3) Monitoring.

(a) Tanks containing product must be inspected at least every seven days.

(b) Tanks must be inspected each time a fertigation operation is performed.