(1) The department shall only approve treatment technologies and distribution technologies that comply with this section.

(2) For public domain treatment technologies with department published recommended standards and guidance and approved specific treatment levels, the design engineer shall submit stamped, signed, and dated design calculations and reference the applicable standards and guidance documents used for the calculations.

(3) For public domain treatment technologies with no department published recommended guidelines and standards, the design engineer shall submit a stamped, signed, and dated engineering report that:

(a) Demonstrates the treatment technology can consistently meet the required treatment level;

(b) Contains supporting information, including flow data, and influent and effluent quality sampling results from a minimum of three LOSS installations with similar design loading to support the performance claim; and

(c) Includes design calculations citing the industry recognized source.

(4) For proprietary treatment technologies registered with the department according to chapter 246-272A WAC, On-site sewage systems, with flows less than 3,500 gpd to the treatment component, the design engineer shall submit stamped, signed, and dated design calculations or references manufacturer sizing guidelines.

(5) For proprietary treatment technologies registered with the department according to chapter 246-272A WAC, On-site sewage systems, and unregistered proprietary treatment technologies with flows 3,500 gpd or greater to the treatment component, the design engineer shall submit a stamped, signed, and dated engineering report that includes:

(a) Dated written confirmation from the proprietary product design engineer stating the technology is suitable for the proposed LOSS and can consistently meet the required treatment level;

(b) Design calculations or references to manufacturer sizing guidelines; and

(c) Supporting information, including flow data, and influent and effluent quality sampling results from a minimum of three LOSS installations with similar design loading to support the performance claim.

(6) For all public domain distribution technologies that the department has developed recommended standards and guidance, the design engineer shall submit stamped, signed, and dated design calculations and reference the applicable standard, guidance, or rule used.

(7) For proprietary distribution technologies that are registered with the department according to chapter 246-272A WAC, On-site sewage systems, the design engineer shall submit stamped, signed, and dated design calculations and reference the applicable standard, guidance, or rule used.