Septic System Policy Changes to be Proposed

Written By: Gary Quackenbush
Published: November 2, 2018

Septic System Policy Changes to be Proposed

Permit Sonoma (formerly PRMD) is planning to propose changes to existing Onsite Wastewater Treatment Systems (OWTS) policies to the Sonoma County Board of Supervisors on November 13. The goal is to ensure that local county regulations comply with the new state requirements. The proposed policy changes would go to the Regional Water Board in the spring of 2019.

Developing a comprehensive OWTS policy has been almost a 20-year process within California that began in 1999 with the passage of AB 885. The State Water Resources Control Board has served as the primary authority for protecting and safeguarding water quality and consequently, reducing any pathogens contained in our local rivers and streams. As such, in 2013 the State Water Board adopted a new policy to meet the state law that requires the development of statewide regulations or standards for septic systems.

While some of these tentative new rules improve the process for obtaining permits for new septic systems and repairs, increased flexibility options and potential variances for homeowners are also part of the mix.

Significant Changes Possible
However, some significant changes in existing policies are being considered, such as a requirement to hire a licensed civil engineer or registered environmental health specialist — instead of a contractor, geologist or soil scientist — to design an OWTS.

An overview of these proposed updates was presented by Tennis Wick, director of Permit Sonoma, and Nathan Quarles, deputy director for engineering and construction, at a special background briefing held at Farm Bureau headquarters October 11.

Quarles said the purpose of the six regional meetings is to gather community feedback on the OWTS policy changes, including Appendix A of the Operating Manual that allows for experimental and alternative septic systems.

“We’re developing a first-pass response to new state regulations revising OWTS policies. At the same time, we are also compiling rules and regulations the county has created over time and packaging them into a single Construction Operations Manual. Sonoma County has been issuing permits for OWTS since the 1970s.”

Changes Won’t Affect Most OWTS Owners
A large percentage (estimated to be about 95 percent) of current OWTS owners that are covered by the policy are expected to experience little or no change in the manner in which their systems are regulated. If an individual OWTS is currently in good operating condition, and it is not near a stream, river, or lake that the State has identified as impaired polluted with bacteria and/or nitrogen-related compounds – then this proposed policy would have little or no effect on that property owner. It is estimated the proposed policy will affect less than five percent of existing OWTS.

The biggest change in the proposed recommendations is the reclassification of when building permits trigger a review of the existing septic system. The proposed triggers include: An increase in effluent flow rate (such as by adding bedrooms); things that can physically affect the OWTS system and a reserve area, and anything that affects the capacity of the land to absorb effluent.

Physical effects can include building a new foundation on top of a septic system, trenching through leach lines, paving over a portion of the dispersal system as well as other land encumbrances that eliminate land from being utilized for septic dispersal areas.

“We want homeowners to have OWTS systems that last for a generation or more, but family growth can be another reason to revise a system – if there is no capacity left in the existing system. We’ve shifted our focus from the size of a rebuild to asking if you are increases the flow or impact the physical septic system.”

Quarles said the mission of Permit Sonoma’s engineering and construction staff is to get the best possible system for a septic site. In the past there was only one way to look at the timing for an onsite evaluation of groundwater elevations, from January to March 15, including a rainy period. This caused a lot of people to do this all at once, which was a burden on the design community or was a problem during drought conditions. Now it may be possible to conduct such evaluations anytime during the year using soil mottling. Soil mottling is a groundwater induced oxidation-reduction process that leave a tell-tale trace in the soil.

Determining Groundwater Elevations
Permit Sonoma is proposing four methods for determining groundwater elevations: Direct observations by use of a backhoe pit or auger borings; direct observation by existing water wells or by monitoring wells; indirect observation via soil mottling; or through the compilation of approved readings or observations from any of the first three methods for adjacent or neighboring parcels and/or projects; or by alternate methods as approved by the Permit Authority.

If a septic system is on a slope greater than five percent, groundwater evaluations are not required.

If a landowner has an existing development or land encumbrance over 50 percent or more of the land, a reserve distribution system area must be set aside.

“The county does not have legal authority to require anyone to upgrade their septic systems or to be on private property. Permit Sonoma only becomes involved if a landowner seeks a building permit, a septic permit or if complaints are received about a failing septic system.”

Replacement, Repair, Emergency Issues
The proposed new county policy codifies what it means to conduct a replacement, a repair and/or an emergency repair of an existing system. A repair includes work within an existing leach line and includes a new leach line if the new leach line is 25 percent or less of the existing system. A repair does not need soil studies or a formal design. A replacement does. If deemed an emergency, Permit Sonoma will expedite the review and permit process.

The State’s OWTS Policy addresses septic systems in close proximity to impaired streams and rivers. For septic systems within 600 feet from specific identified streams with impaired water, mainly the lower Russian River and specific tributaries, rules are being developed to effect remediation. The 600-foot limit refers to the distance that enables bacteria to be absorbed in the soil.

Under the state’s OWTS Policy, if an OWTS system is within the 600-foot zone, land owners have three choices: The owner must have a supplemental treatment system, local administrators can develop an Advanced Protection Management Program (APMP), or a remediation plan can be developed to be consistent and within compliance with the regional Total Maximum Daily Load (TMDL) standard. The county intends to draft an APMP when TMDL standards are approved by the North Coast Regional Water Board.

The TMDL Process
Each state is required by federal law to routinely assess the quality of its surface waters to determine if they support beneficial water uses. Common beneficial uses for surface water include drinking water, support of aquatic life, and recreational contact-sports such as swimming. Owners of OWTS that are located adjacent to a surface waterbody that exceeds water quality standards for bacteria (E.coli, etc.) or nitrates, may have to retrofit the septic system using supplemental treatment.

Maps of water bodies impaired by bacteria (pathogens) or nitrogen compounds can be viewed on the State Water Board’s website. Select the Map tab to view specific pollutants: (

In keeping with this mandate, the North Coast Regional Water Board is proposing to require on-site OWTS inspections every five years for septic systems within TMDL (Total Maximum Daily Load) designated areas, such as the Russian River watershed and other bodies of water identified as having widespread contamination from bacteria or other pathogenic organisms indicating the presence of human and animal waste.

The Regional Water Board is proposing additional regulation regarding the types of septic systems that will be acceptable within the TMDL area. It is anticipated these regulations will be available later this year.

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