The SHD policy titled “Supplemental Procedures Regarding: On-Site Sewage System Installer Certification and Installation Requirements” prescribes the activities associated with installer certification and minimum standards for system installation. Revisions or modifications to the policy shall be approved by the Director of Environmental Health. [Res. 12-15. Res. 08-10. Revised and reapproved by DOH 12/15/94. Res. 93-32, Eff. 11/09/93. Res. 89-61. Prior code § 8.3(III)].