On-Site Septic System Permits

  1. Permits, Test Pits, and Site/Soil Evaluations
  2. Operation and Maintenance
  3. Septic System Loan Program - Craft 3
  4. Connect to Existing OSS


Wahkiakum County Health and Human Services issues septic installation permits for new construction and repairs. Septic installation permit applications must be accompanied by two copies of a septic system design prepared by a licensed on-site wastewater treatment system designer or professional engineer. 

Additionally, we offer site and soil evaluations for determining the feasibility of installing a new septic system and for dividing land (short plats). On-Site Sewage Systems WAC 246-272 (PDF) is the current code for the regulation of septic systems.

For most projects, we recommend contacting a licensed installer and/or designer to get your project started. The county maintains a list of contractors and designers who have been asked to be placed on our list.

Test Pits

Test pits are required in order for the county and the designer to evaluate the soil to determine if a septic system can be installed in that area and what type of septic system must be installed. Test pits should be spaced approximately 60' apart and constructed in accordance with the Guidelines for Test Pit Construction for On-Site Sewage Systems (PDF).

For new construction projects, three test pits must be dug. Two in the primary drain field area (drain field to be installed) and one in the reserve drain field area (shown on paper for future replacement area). For repair/replacements, two test pits must be dug in the area intended to be used for the new drain field.

Site & Soil Evaluations

Wahkiakum County Health and Human Services performs site and soil evaluations for determining the feasibility of installing septic systems on bare land, and for land divisions. 

Site and soil evaluation applications must include a site plan showing:

  • Buildings
  • Driveways
  • Existing utilities and easements
  • Location of the test pits
  • Roads
  • Springs
  • Surface waters
  • Wells