(1) Biosolids must be applied to the land in a manner approved by the department and at agronomic rates, except when approved by the department for land reclamation sites in accordance with subsection (3) of this section or for research purposes when approved by the department in accordance with WAC 173-308-192 or in a site-specific land application plan developed under WAC 173-308-310(8).

(2) Agronomic rate determinations must take into account nitrogen supplied from other sources such as manures, cover crops, and commercial fertilizers as well as biosolids.

(3) Biosolids applied to land reclamation sites may be applied in excess of agronomic rates if approved by the department in a site specific land application plan developed under WAC 173-308-310(8).

(4) The person who prepares exceptional quality biosolids that are sold or given away to another person must provide sufficient information to allow the person who receives the biosolids to determine an agronomic rate of application.

(5) The person who applies exceptional quality biosolids to the land is responsible for compliance with the agronomic rate requirement in this section.

(6) When the potential for groundwater contamination due to biosolids application exists, the department may require groundwater monitoring or other conditions in accordance with the provisions of chapter 173-200 WAC. If it is determined that an enforcement criterion may be violated, an evaluation must be conducted to demonstrate compliance with the provisions of chapter 173-200 WAC.