Septic O&M Forms

Depending on the type of septic system that you have there are different requirements. The first item below is a full length guide to filling out the forms and performing the inspection. The other documents are various forms. You will need to fill out at least the first form and, depending on system type, perhaps one of the others as well.

Homeowners Guide to Septic Operations & Maintenance Inspections
For best results, please download the report & form and open in a PDF viewer (e.g., Foxit or Adobe Reader) before filling out. This booklet is a companion guide to assist homeowners in completing Form 8420 OSS O&M Gravity-Pressure Distribution Report and Form 8422 OSS O&M Sand Filter Supplement.  This guide is not a substitute for the homeowner operations and maintenance training required prior to performing an O&M inspection on all systems other than gravity and pump-to-gravity OSS. It is intended to assist you, the homeowner, in properly filling out Form 8420. If you have a sand filter pre-treatment unit before your drainfield, you will also need to complete the “Sand Filter Supplement” Form 8422.

Standard O&M inspection form:

• Gravity and Pressure Distribution
  This is the basic form that needs to be filled out for all types of septic systems.

Supplemental O&M inspection forms:

• Sand Filter
  Add this form if the septic system includes a sand filter
• Sand Media
  Add this form if the septic system involves sand media (e.g. Sand Mounds, Sand Lined Trenches, etc.)
  NOTE: Do not use this form for sand filters
• Aerobic Treatment Unit (ATU)
  For best results, please download this form and open in a PDF viewer (e.g., Foxit or Adobe Reader) before filling out.
  Add this form if the septic system involves an Aerobic Treatment Unit. 
  NOTE: ATUs are considered proprietary, as defined in WAC 246-272A-0010, and must be inspected by a Cowlitz County licensed O&M professional specifically approved for that product by the manufacturer