Thurston County, Washington septic permits and requirements

Permitting authority

Thurston County Environmental Health — Septic & Onsite Sewage Program

Environmental Health: 360-867-2673; [email protected]; Thurston County, 3000 Pacific Avenue SE, Olympia, WA 98501.

Washington local-health-jurisdiction framework

Washington State Department of Health places property-level onsite sewage permitting and management with local health jurisdictions. Local agencies review and approve OSS siting, design, installation, repair, and operation under Chapter 246-272A WAC and may adopt local requirements that are more protective than the statewide minimums.

Septic permit precedes other development permits on undeveloped property

For a new home or undeveloped property not connected to sewer, Thurston County requires a septic system permit prepared by a licensed septic-system designer or professional engineer. County guidance states that these septic permits come before other development permits.

Test holes, design and county site review

The hired designer or professional engineer performs the test-hole work and prepares the site plan showing the proposed septic system and drinking-water source. After submittal, county staff review the packet and visit the property to evaluate soils and site conditions; the county may issue a Conditional Site Approval with additional conditions.

Record Drawing and Operational Certificate

After installation, the designer submits the installed-system Record Drawing to the county. Once the Record Drawing is accepted, Thurston County issues an Operational Certificate. Depending on the system type and location, the Operational Certificate can require routine renewal.

Final septic inspections

Thurston County states that septic installers typically contact Environmental Health to schedule final inspections after installation. Applicants should not assume the system is complete until the required Environmental Health inspection and documentation steps are satisfied.

Official sources

SepticScope summarizes public-agency information for planning purposes. The permitting agency's current instructions control if they differ from this guide.