August 18th, 2025

OSS DESIGNERS,

This special edition newsletter is being sent to all OSS designers who operate in Snohomish County. Please note the following updates when submitting new septic applications and creating site plans.

Septic App Update: Treatment Level N

What is happening?
A box for Treatment Level N (TLN) has been added to the septic application form under "Pretreatment Type".

Why?
WAC 246-272A-0320
DOH Technical Guidance for Contaminants of Emerging Concern in Wastewater

When will this start?
Starting today, the septic application form on our website and online form now have this box as an option.

Septic Application with Treatment Level N Box

New Site Plan Requirements

What is happening?
Snohomish County Health Department will be checking for new, additional site plan requirements. New requirements include:

A legend of symbols used
A plan scale and graphic scale bar
Vertical datum used such as “assumed”, “NAVD 88”, “NSRS”, or “unknown”
Contact information of the designer
A statement of limitation of use indicating the site plan is not a survey

Why?
Due to April 1st WAC revisions
WAC 246-272A-0200 Permit requirements

When will this start?
We will begin checking for these site plan requirements beginning September 1st.

Questions? Contact us!

Email: SHD-EHQ@snoco.org

Call: (425) 339-5250