Article 1 — DEFINITIONS AND GENERAL PROVISIONS

The purpose of this chapter is to establish standards for the siting, design, installation, and operation of Onsite Wastewater Treatment Systems (OWTS) in San Mateo County, consistent with the Water Quality Control Policy for Siting, Design, Operation and Maintenance of Onsite Wastewater Treatment Systems, adopted by the State Water Resources Control Board on June 19, 2012, which became effective May 13, 2013 (SWRCB OWTS Policy), and with California Regional Water Quality Control Board (CRWQCB) standards and basin plans. These standards are adopted to prevent the creation of health hazards and nuisance conditions and to protect surface and groundwater quality from threats of sewage.

(Ord. No. 04754, § 1, 1-5-2016)

This chapter shall be administered and enforced by Environmental Health in San Mateo County. Environmental Health shall coordinate the permitting of OWTS within incorporated cities with each city.

(Ord. No. 04754, § 1, 1-5-2016)

a.

Policy, procedural and technical details for implementation of this chapter shall be contained in a document titled the Onsite Systems Manual, available on the San Mateo County Environmental Health Services Division website.

b.

The Onsite Systems Manual shall be developed and maintained by Environmental Health, and shall provide a reasonable process for seeking input from the affected public and OWTS practitioners, such as OWTS designers and installers, regarding its development and any changes made to it.

c.

The Onsite Systems Manual and any amendments to it shall be subject to approval by Environmental Health and the San Francisco Bay and Central Coast Regional Water Quality Control Boards in accordance with applicable state requirements and policies for onsite wastewater treatment.

d.

The type and manner of design and construction of OWTS shall conform to the standards as required by this chapter and the Onsite Systems Manual.

(Ord. No. 04754, § 1, 1-5-2016)

a.

The following terms used in this chapter have the same definition as in the SWRCB OWTS Policy, which is available on the San Mateo County Environmental Health Services Division website: Cesspool, domestic wastewater, groundwater, impaired water body, onsite wastewater treatment system (OWTS), replacement OWTS, seepage pit, septic tank, site evaluation, soil, supplemental treatment, total maximum daily load (TMDL), and waste discharge requirement.

b.

The following terms used in this chapter are defined as follows:

"Alternative OWTS" is a type of OWTS that utilizes either a method of wastewater treatment other than a conventional septic tank for the purpose of producing a higher quality wastewater effluent and/or a method of wastewater dispersal other than a gravity-fed trench dispersal system for effluent dispersal.

"Conventional OWTS" means a type of OWTS consisting of a septic tank for primary treatment of sewage followed by gravity flow to a dispersal system of drainfield trenches for subsurface dispersal of effluent into the soil.

"Cut" or "embankment" means any area of land surface having a distinctly greater slope than the adjacent natural ground surface, greater than 36 inches in vertical height, and any part of which is lower in elevation than the ground surface at the nearest point of the OWTS. Cuts supported by retaining walls or similar structures shall be included in this definition, as shall steep natural ground surfaces where a sharp break in the ground slope is discernible.

"Dispersal system" means a series of trenches, beds, subsurface drip lines, or other approved method for subsurface infiltration and adsorption of wastewater effluent, including all component parts, such as piping, valves, filter material, chambers, dosing pumps, siphons and/or other appurtenances.

"Drainage swale" means any course of concentrated drainage water that has formed over time by either natural or man-made forces and where the flow of water is either at or near ground surface with no significant subsurface flow component. Also included in this definition are facilities used for the treatment and/or dispersal of roof runoff or other site drainage, such as vegetated swales and infiltration/percolation trenches or basins.

"Environmental Health" means the Director of Environmental Health Services Division of San Mateo County or his/her designee.

"Holding tank" means a watertight receptacle used to collect and store wastewater prior to it being removed from a property by means of vacuum pumping and hauling or another approved method.

"Operating permit" means the administrative document issued by Environmental Health authorizing the initial and/or continued use of an alternative OWTS in conformance with the provisions of this chapter and the Onsite Systems Manual. An operating Permit may also be issued in connection with holding tank exemptions, portable toilet installations, or where Environmental Health determines that the type, size, location or other aspects of a particular OWTS installation warrant an additional level of oversight provided through the issuance of an operating permit.

"OWTS failure" means the ineffective treatment and/or dispersal of waste resulting in the surfacing of raw, or inadequately treated sewage effluent, or the degradation of surface or groundwater quality as it creates a potential public health hazard. For a dispersal system, signs of OWTS failure may include surfacing wastewater effluent from the dispersal field or wastewater backed up into plumbing fixtures, including septic tank, because the dispersal system is not able to percolate the design flow of wastewater associated with the structures served. For a septic tank, signs of OWTS failure may include compartment baffle buckling or failure or tank structural integrity failure such that either wastewater is exfiltrating or groundwater is infiltrating.

"Portable toilet" means an enclosed unit intended for temporary use at a given location. Portable toilets may also be referred to as "chemical toilets" in other County ordinances or California statute or regulation.

"Pressure-dosing distribution" means a method of wastewater dispersal used to achieve equal distribution of wastewater within a dispersal field by employing a pump or automatic dosing siphon and distribution piping with small diameter holes or perforations spaced uniformly along its length.

"Qualified OWTS Design Professional" means an individual licensed or certified by a State of California agency to design OWTS and practice as a professional as allowed under their license or registration. An individual who certifies OWTS designs must be a State of California Registered Environmental Health Specialist, Professional Geologist, or Professional Civil Engineer.

"Soil percolation testing" is a method of evaluating water absorption of the soil. The test is conducted with clean water and test results are used in the design and sizing of the dispersal system.

"Unstable land mass" means land prone to subsidence, erosion, or mass land movement as indicated by historical landslide events, published maps or reports, or evidence of characteristics such as surface rupture, scarps, creep or other irregularities in ground slope conditions.

"Watercourse" means a definite channel with bed and banks within which water flows either perennially, ephemerally or intermittently, including overflow channels contiguous to the main channel. A watercourse may be either a natural or man-made channel. For purposes of this chapter, watercourse also includes water bodies such as ponds, lakes, marshes, seasonal wetlands and tidal waters.

(Ord. No. 04754, § 1, 1-5-2016)

a.

OWTS may be considered for the treatment and dispersal of domestic wastewater where a sanitary sewer is not available consistent with the provisions of section 4.84.040 of this chapter.

b.

This chapter applies to premises where there is proposed or exists a residence, place of business or other building or place which people occupy, or where Persons congregate, reside or are employed and where the maximum daily flow volume of wastewater produced is ten thousand gallons per day (10,000 gpd) or less.

c.

If the amount of wastewater produced is more than ten thousand gallons per day (10,000 gpd), or where a community system serving multiple discharges under separate ownership is proposed, the method of wastewater treatment and dispersal must be approved by the appropriate CRWQCB consistent with the requirements of section 4.84.125 of this chapter. Any proposed OWTS with projected daily wastewater flow of more than two thousand five hundred gallons per day (2,500 gpd) will be referred by Environmental Health to the appropriate CRWQCB for review and will require the issuance of an operating Permit as provided in section 4.84.155 of this chapter.

d.

For any existing or new OWTS within an area determined to require advanced protection management, such OWTS may require supplemental treatment of effluent and additional monitoring and reporting to Environmental Health consistent with section 4.84.175 of this chapter.

e.

For any subdivision of land proposed to be served by an OWTS, the subdivider must demonstrate that the OWTS design and siting is consistent with this chapter and the Onsite Systems Manual.

f.

The requirements in this chapter and the Onsite Systems Manual shall apply to any application for Permit issued by Environmental Health, and any applications for any services administered by Environmental Health, which are required by this chapter and that are submitted on or after the effective date of this chapter.

(Ord. No. 04754, § 1, 1-5-2016)

The County, its officers, agents and employees are not liable or responsible for damage resulting from the defective construction of any OWTS as herein provided, nor will the County or any official or employee thereof be liable or responsible by reason of any inspection authorized hereunder.

(Ord. No. 04754, § 1, 1-5-2016)

a.

Every property where there is proposed a residence, place of business, or other building or place which people occupy, or where Persons congregate, reside or are employed, and which proposed structures requiring sewage disposal are within two hundred (200) feet of an approved available sanitary sewer, must be connected to the sanitary sewer in the most direct manner possible, provided a right-of-way and any necessary approval from the appropriate sewer authority and the San Mateo County Local Agency Formation Commission is first obtained.

b.

On property where an OWTS exists, and which structures served by an OWTS are within two hundred (200) feet of an approved available sanitary sewer, connection to the available sanitary sewer will be required at the time of OWTS failure or when replacement or addition to the OWTS is required or proposed, provided any necessary approval from the appropriate sewer authority and the San Mateo County Local Agency Formation Commission is first obtained.

(Ord. No. 04754, § 1, 1-5-2016)