Application tanks functionally connected to and dedicated solely for use with a chemigation system may be exempt from the secondary and operational area containment rules (chapter 16-229 WAC). The following conditions determine whether a tank that is a component of a chemigation 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 fourteen days between chemigation applications. If the fourteen-day period is exceeded, the tank is deemed to be 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 16-229 WAC).

(2) Tank size.

(a) Tanks with a rated capacity exceeding two thousand five hundred gallons are deemed a permanent storage facility.

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

(c) Exception for soil fumigation only: Beginning at the time of tank placement, a tank with a rated capacity of eight thousand gallons or less may be placed at an injection site for fourteen days or less. However, during the fourteen-day period, the cumulative quantity of product at an injection site whether in single or multiple tanks cannot exceed six thousand five hundred gallons. The injection site shall be deemed a permanent storage facility provided, if at anytime during the fourteen-day time-in-place period, the rated capacity of an individual tank exceeds eight thousand gallons or the cumulative quantity at an injection site exceeds six thousand five hundred gallons.

(3) Monitoring.

(a) Tanks containing product must be inspected at least daily or monitored with remote access volumetric measuring devices.

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