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Outreach for Public Comment on Onsite Wastewater Treatment System (OWTS) Manual

Published:  May 27, 2016

The OWTS Manual has been approved by the Board of Supervisors and submitted to the Water Board. Please read  the following memo for further information. You may review submitted comments and incorporated responses in the updated version of the OWTS Manual.

To Sonoma County Clerk

Permit and Resource Management Department,

Well & Septic Division

Subject Post proposed standards for a 30 day public comment period
Date May 18, 2016

Pursuant to Sonoma County Code Chapter 24-31.5, the Director of the Permit and Resource Management Department (PRMD) may from time to time adopt and promulgate standards for on-site waste water disposal systems. Every proposed standard, proposed revised standard, or standard proposed to be rescinded shall be posted in the office of the Sonoma County Clerk and in a public area of the Permit and Resource Management Department office for a minimum period of at least fifteen (15) days, together with a notice that the public may submit written comments for the director’s consideration not later than the thirtieth (30th) day following posting of notice.

Please post the enclosed Onsite Wastewater Treatment System Regulations and Technical Standards (OWTS Manual). This document is proposed to replace in its entirety the current Regulations for Onsite Sewage Disposal in Sonoma County. 

The OWTS Manual is primarily a reformatted version of existing County regulations and standards to comply with the State Water Resources Control Board OWTS Policy Tier 2 Local Area Management Program (LAMP) requirements. The purpose of this document is to allow continued PRMD authorization for oversight of OWTS countywide. This document was reviewed by a subcommittee of the Land Use Advisory Panel in January 2016.  Then in March 2016 it was published for public review and comment.  Attached for reference are the comments and responses from those reviews.

The main changes include the following:

  • Section 1.4 Limitations:  Maximum daily flow volume of OWTS subject to County oversight, increased from 1500 gallons per day (gpd) to 10,000 gpd
  •  Section 3 Definitions:  Several definitions added/revised to correspond with relevant Building and Planning Division definitions
  • Section 5 OWTS Repairs:  Minor revision/clarification of existing OWTS Repair Policy requirements and restrictions
  • Section 6: OWTS Requirements for Approval of Building Permits:  Revisions/clarification of OWTS requirements and restrictions as they relate to Building Permit approvals to replace previous Remodel Policy
  • Section 8.6 Criteria for OWTS Components:  New requirements for Intercept Drains
  • Section 9.4 Criteria for Standard OWTS:  Shallow Trench Pressure Distribution Systems (STPD) that meet the site and soil criteria for a standard system are not subject to the Operational Permit  requirement
  • New Section 10 Criteria for Water Reuse-Graywater
  • Section 11.2 Criteria for Commercial OWTS:  New requirements for Winery OWTS
  • Section 11.4 Criteria for Commercial OWTS:  New requirements for Flow Equalization
  • Section 12.4 Criteria for Non-Standard Experimental OWTS:  Addition of Bottomless Sand Filters (beyond existing geographical waiver restrictions) and Gravel-less Pressurized Dispersal Channel (GPDC) as new Experimental OWTS
  • Section 13 Criteria for Non-Standard Alternative OWTS:  Shallow In Ground (SIG) OWTS and Subsurface Drip Dispersal OWTS moved from Non-Standard Experimental to Alternative OWTS status. New standards for Subsurface Drip Dispersal OWTS
  • Section 14 Non-Standard and/or Commercial OWTS Operational Permit and Monitoring.  New Service Provider requirements.
  • Section 17 Variance Requirements: New criteria for variance requests and approvals
  • New and revised tables
  • New and revised figures

Written comments may be directed to Bob Swift at the Permit and Resource Management Department 2550 Venture Ave., Santa Rosa, CA 95403 or at Please use the following format for written comments: Commenter’s Name | Policy Section Number | Comment.

Requests for a copy of the proposed standards may be directed to, Well and Septic Division Supervisor.

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