Application tanks functionally connected to and dedicated solely for use with a chemigation or fertigation system may be exempt from the secondary and operational area containment rules in chapter 16-201 WAC (commercial fertilizers) and chapter 16-229 WAC (pesticides) when in compliance with the conditions found in this section.

(1) Time-in-place.

(a) Pesticides can remain in an application tank for a period not to exceed 14 days between chemigation applications. If the 14-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) Commercial fertilizers 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.

(c) 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.

(d) The application tank must be emptied, cleaned, visually inspected for integrity, and serviced at the end of the irrigation or application season or after nine months, whichever is shorter, and then:

(i) Removed from the site;

(ii) Decommissioned and clearly tagged with the words "out-of-service"; or

(iii) Managed as a permanent storage facility per the requirements in chapter 16-201 WAC (for commercial fertilizers) and chapter 16-229 WAC (for pesticides).

(2) Chemigation tank size.

(a) Tanks with a rated capacity exceeding 2,500 gallons are deemed a permanent storage facility.

(b) Multiple tanks positioned at an injection site with a cumulative capacity exceeding 3,000 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 8,000 gallons or less may be placed at an injection site for 14 days or less. However, during the 14-day period, the cumulative quantity of product at an injection site whether in single or multiple tanks cannot exceed 6,5000 gallons. The injection site shall be deemed a permanent storage facility provided, if at any time during the 14-day time-in-place period, the rated capacity of an individual tank exceeds 8,000 gallons or the cumulative quantity at an injection site exceeds 6,500 gallons.

(3) Fertigation tank size.

(a) An application tank with a rated capacity exceeding 6,500 gallons is deemed a permanent storage facility.

(b) Multiple tanks positioned at an injection site cannot exceed 10,000 gallons per application system.

(4) Tank monitoring.

(a) Tanks containing a pesticide must be inspected at the beginning of a chemigation operation and at least daily thereafter or monitored with remote access volumetric measuring devices.

(b) Tanks containing a commercial fertilizer must be inspected at the beginning of each fertigation operation and at least every seven days or monitored with remote access volumetric measuring devices thereafter.