Santa Clara County Municipal Code § B11-60 Intent and application

The purpose of this Chapter is to establish standards for the approval, installation, and operation of onsite wastewater treatment systems (OWTS) within Santa Clara County, consistent with the appropriate California Regional Water Quality Control Board OWTS Ordinance standards and basin plans. The standards are adopted to prevent the creation of health hazards and nuisance conditions and to protect surface and groundwater quality.

OWTS may be considered for the treatment and dispersal of domestic sewage where a sanitary sewer is not available consistent with the provisions of Section B11-62 of this Chapter. No hazardous wastes shall be discharged into any OWTS.

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 waste produced is 10,000 gallons per day or less.

If the amount of waste produced is more than 10,000 gallons per day, or where a community system serving multiple discharges under separate ownership is proposed, the method of treatment and dispersal must be approved by the appropriate California Regional Water Quality Control Board consistent with the requirements of Section B11-66 of this Chapter. Any proposed OWTS with a projected daily wastewater flow of more than 2,500 gallons per day will be referred by the Director to the appropriate California Regional Water Quality Control Board for review and will also require the issuance of an operating permit as provided in Section B11-92 of this Chapter.

New divisions of land using OWTS shall be limited to a minimum parcel size of one acre, or to a minimum parcel size of two and one-half acres if within a reservoir watershed.

For any subdivision of land, the subdivider must demonstrate that the onsite wastewater treatment system(s) design and siting is consistent with Section B11-67 of this Chapter.

(Ord. No. NS-517.85, § 2, 11-26-13; Ord. No. NS-300.1002, § 13, 10-21-25)

The County is 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. NS-517.85, § 2, 11-26-13)

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 abuts a street or alley in which there exists an approved available sanitary sewer, or which property line is within 300 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 Santa Clara County Local Agency Formation Commission is first obtained. On property where an OWTS exists, and where such property abuts a street or alley in which there exists an approved available sanitary sewer or which property line is within 300 feet of an approved available sanitary sewer, connection to the available sanitary sewer will be required at the time of system failure or when the building is remodeled, increased in square footage or altered in a manner as to change uninhabitable space into habitable space provided any necessary approval from the appropriate sewer authority and Santa Clara County Local Agency Formation Commission is first obtained.

(Ord. No. NS-517.85, § 2, 11-26-13)

(a) No person may construct, add to, repair, alter, or maintain any OWTS, sewer pipes, or conduits, or any other conduits for the treatment or discharge of sewage, impure waters, or any matter or substance offensive, injurious, or dangerous to health so as to cause any of the following to occur:

(1) Sewage, impure waters, or any matter or substance offensive, injurious, or dangerous to health to empty, flow, seep, or drain onto the surface of any land.

(2) Sewage, impure waters, or any matter or substance offensive, injurious, or dangerous to health to empty, flow, seep, drain into, or affect any well, spring, stream, river, lake, or other waters.

(3) Result in any condition which, in the opinion of the Director, is unsafe or dangerous, or creates a nuisance.

(b) A violation of this Section is hereby declared a public nuisance.

(Ord. No. NS-517.85, § 2, 11-26-13; Ord. No. NS-300.1002, § 14, 10-21-25)

As used in this Chapter, the following terms and phrases have the following meaning:

(a) Alternative OWTS means a type of OWTS that utilizes either a method of wastewater treatment other than a conventional septic tank and/or a method of wastewater dispersal other than a conventional drainfield trench for the purpose of producing a higher quality wastewater effluent and improved performance of and siting options for effluent dispersal.

(b) At-grade means a type of dispersal system consisting of a gravel distribution bed placed on top of a tilled, in situ soil absorption area, which is then covered by a minimum of 12 inches of suitable soil that will support vegetative growth. Wastewater effluent is applied to the gravel distribution bed using pressure distribution.

(c) Basin plan means the same as "water quality control plan" as defined in Division 7 (commencing with Section 13000) of the California Water Code. Basin plans are adopted by each Regional Water Quality Control Board, approved by the State Water Board and the Office of Administrative Law, and identify surface water and groundwater bodies within each Region's boundaries and establish, for each, its respective beneficial uses and water quality objectives.

(d) Bedrock means the rock, usually solid, that underlies soil or other unconsolidated, earthen material.

(e) Beneficial uses means those qualities in waters of the state that may be protected against quality degradation that include, but are not necessarily limited to, domestic, municipal, agricultural, and industrial supply; power generation; recreation; esthetic enjoyment; navigation; and preservation and enhancement of fish, wildlife, and other aquatic resources or preserves.

(f) Cesspool means an excavation in the ground receiving domestic wastewater, designed to retain the organic matter and solids, while allowing the liquids to seep into the soil. The use of cesspools is not authorized in Santa Clara County.

(g) Community system means an OWTS that provides for the collection, treatment, and dispersal of wastewater from multiple discharges under separate ownership. Community systems are subject to review and approval of the applicable California Regional Water Quality Control Board.

(h) Conventional OWTS means a type of OWTS consisting of a septic tank for primary treatment of sewage followed by a system of drainfield trenches for subsurface dispersal of effluent into the soil. A conventional OWTS may utilize gravity flow or a pump system to convey effluent from the septic tank to the drainfield.

(i) Cut or embankment means any altered area of land surface having a distinctly greater slope than the adjacent natural ground surface, over 24 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.

(j) Cumulative impacts means the persistent and/or increasing effect of OWTS resulting from the density of such discharges in relation to the assimilative capacity of the local environment. Examples include but are not limited to: (a) nitrate or salt additions to ground water or surface water; and (b) rise in groundwater levels ("mounding of the water table") that interferes with the performance of an OWTS, causes drainage problems or results in other adverse hydrological or soil conditions affecting public health, water quality, or public safety.

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

(l) Domestic wastewater means wastewater with a measured strength less than high-strength wastewater and is the type of wastewater normally discharged from, or similar to, that discharged from plumbing fixtures, appliances, and other household devices including, but not limited to, toilets, bathtubs, showers, laundry facilities, dishwashing facilities, and garbage disposals. Domestic wastewater may include wastewater from commercial buildings, such as office buildings, retail stores, and some restaurants, or from industrial facilities where the domestic wastewater is segregated from the industrial wastewater. Domestic wastewater does not include wastewater from industrial processes or recreational vehicle dump stations.

(m) Drainage swale means any course of concentrated drainage water that has formed over time by either natural or manmade forces, and where the flow of water is either at or near ground surface.

(n) Drainageway means an unlined channel, with definite bed or banks, which conveys stormwater runoff and provides surface hydraulic continuity with either seasonal or perennial streams or water bodies. 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.

(o) Drainfield means a system of rock-filled trenches or beds that distribute treated sewage effluent for subsurface dispersal into the soil. A drainfield is also known as a "leachfield" or a "soil absorption system."

(p) Failure means the ineffective treatment and dispersal of waste resulting in the surfacing of raw or inadequately treated sewage effluent and/or the degradation of surface or groundwater quality.

(q) Geotechnical report means a written document used to communicate soil and geologic site conditions, interpretations, analysis and recommendations pertinent to the design, installation and operation of an OWTS in areas of steeply sloping terrain. A primary emphasis of the geotechnical report is the evaluation of potential slope stability issues that may be affected by or result in impacts to the operation of the proposed OWTS. An additional purpose of a geotechnical report may be to provide site specific recommendations regarding appropriate horizontal setbacks from cut banks, steep slopes, and unstable land masses.

(r) Groundwater means water below the land surface that is at or above atmospheric pressure.

(s) High-strength wastewater means wastewater having a 30-day average concentration of biochemical oxygen demand (BOD) greater than 300 milligrams-per-liter (mg/L) or of total suspended solids (TSS) greater than 330 mg/L or a fats, oil, and grease (FOG) concentration greater than 100 mg/L prior to the septic tank or other OWTS treatment component.

(t) 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 other approved method. The use of holding tanks in Santa Clara County is authorized for limited circumstances, including, but not limited to, for the abatement of health hazards or for certain public use facilities.

(u) Intermittent sand filter means a packed-bed filter of medium-grained sand used to treat septic tank effluent to an advanced level. The sand filter consists of a lined excavation or structure filled with uniform clean sand, with an under-drain system at the bottom. The wastewater is dosed to the surface of the sand through a pressure-distribution network and allowed to percolate through the sand where biochemical oxygen demand (BOD) is reduced and suspended solids are removed; treatment is accomplished by physical filtration as well as microbial growth on the surface of the sand grains. After a single pass, the treated water is collected in the under-drain for further processing or disposal.

(v) Mound means an OWTS consisting of above-ground sand bed placed over a tilled, native soil absorption area, on top of which is placed a bed of gravel for distribution of septic tank effluent, which is then covered by suitable soil to stabilize the surface and support vegetative growth. Effluent is applied to the gravel distribution bed using pressure distribution.

(w) Onsite Systems Manual means the document developed, maintained, and amended by the Santa Clara Environmental Health branch of the Public Health Department containing policy, procedural and technical details for implementation of this Chapter, as prescribed by the Director and approved by the appropriate California Regional Water Quality Control Boards, as applicable.

(x) Onsite wastewater maintenance provider means a person capable of operating, monitoring and maintaining an OWTS in accordance with the requirements of this Chapter, and possessing minimum experience and qualifications as established by the Director in the Onsite Systems Manual.

(y) Onsite wastewater treatment system (OWTS) means a system of pipes, tanks, trenches, and other components used for the collection, treatment, and subsurface dispersal of domestic wastewater at or near the building or buildings being served. The short form of the term may be singular or plural. For the purposes of this Ordinance, OWTS do not include "graywater" systems pursuant to Health and Safety Code section 17922.12.

(z) Operating permit means the administrative document issued by the Director authorizing the initial and/or continued use of an alternative OWTS in conformance with the provisions of this Ordinance, intended to aid in verification of the adequacy of alternative OWTS performance, and that may contain both general and specific conditions of use. An operating permit may also be issued for circumstances other than alternative OWTS, such as in connection with holding tank exemptions or where, in the opinion of the Director, the type, size, location, or other aspects of a particular OWTS installation warrant the additional level of oversight provided by an operating permit.

(aa) Percolation test means 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.

(bb) Permeable soil means soil having a percolation rate of 120 minutes per inch or faster or having a clay content of less than 60 percent, and shall not include solid rock formations or those that contain continuous channels, cracks, or fractures.

(cc) Installation permit means a document issued by the Director that conveys approval of and sets forth applicable conditions for the installation of an OWTS, or component thereof.

(dd) Portable toilet means an enclosed unit intended for temporary use at a given location. Portable toilets can also be known as, but not limited to, chemical toilets in this Chapter.

(ee) Pressure distribution means a method of wastewater dispersal employing a pump or automatic dosing siphon and distribution piping consisting of small diameter plastic pipe with small perforations spaced uniformly along its length; it is used to achieve equal distribution of wastewater within a treatment unit (such as a sand filter) or a dispersal field.

(ff) Pressure-dosed sand trench means an alternative dispersal system consisting of a variation of a shallow pressure distribution system that utilizes specially graded sand in place of gravel to backfill the bottom portion of the dispersal trench, improving the treatment of effluent, and controlling the percolation rate before it reaches the trench bottom.

(gg) Raised sand filter bed means an alternative dispersal system consisting of a raised or terraced sand bed, commonly supported by a low retaining wall or bulkhead, where the bottom surface is even with or slightly below ground surface and forms the absorption surface. Used following a supplemental treatment unit, the raised sand bed provides additional polishing treatment and final dispersal of water into the ground.

(hh) Recirculating sand filter means a packed-bed filter of coarse-grained sand used to treat septic tank effluent to an advanced level. It is a modified version of an intermittent (single pass) sand filter which includes a recirculation system that causes the wastewater to pass through the sand media several times prior to final dispersal, usually controlled by a timer.

(ii) Regional Water Quality Control Board (RWQCB) means the California Regional Water Quality Control Boards designated by Water Code section 13200, which have authority for adopting, implementing, and enforcing water quality control plans (basin plans) which set forth the State's water quality standards and the objectives or criteria necessary to protect those beneficial uses. There are two RWQCBs having jurisdiction over different parts of Santa Clara County: San Francisco Bay Region (2), and Central Coast Region (3). Any reference to the Regional Water Quality Control Board in this Ordinance also refers to an action of its Executive Officer, including the conducting of public hearings, pursuant to any general or specific delegation under Water Code section 13223.

(jj) Registered Septic Tank Pumper means a person with an active liquid waste pumper permit issued by the Director, per Santa Clara County Code Division B11, Chapter X, beginning with section B11-210, as qualified to pump and haul septic tank sludge ("septage") and to perform service inspections of septic tanks and associated components of OWTS as required in this Chapter.

(kk) Sanitary sewer means a system for collecting residential or municipal wastewater and directing the collected wastewater to a treatment works prior to dispersal.

(ll) Septic tank means a watertight, covered receptacle designed and constructed for primary treatment to receive the discharge of sewage from a building sewer, separate solids from the liquid, digest organic matter, and store digested solids through a period of detention, and allow the clarified liquids to discharge for supplemental treatment and/or final dispersal.

(mm) Shallow pressure-distribution trench means an alternative dispersal system which consists of a variation of a conventional gravity drainfield that uses a pump and small-diameter pressure piping to achieve broad, uniform distribution of wastewater in the shallow soil zones for improved soil absorption and enhanced treatment of percolating effluent.

(nn) Site means the land area occupied, or proposed to be occupied, by the OWTS, including any designated reserve area.

(oo) Site evaluation means an assessment of the characteristics of the site sufficient to determine its suitability for an OWTS to meet the requirements of this Chapter. Site evaluations shall be in accordance with procedures and criteria established by the Director and contained in the Onsite Systems Manual.

(pp) Soil means the naturally occurring body of porous mineral and organic materials on the land surface, which is composed of unconsolidated materials, including sand-sized, silt-sized, and clay-sized particles mixed with varying amounts of larger fragments and organic material.

(qq) Subsurface drip dispersal means a method for releasing treated wastewater to the soil for final treatment and dispersal via small diameter flexible plastic tubing manufactured with emitters spaced uniformly along its length; the drip field is designed and installed such that the drip tubing is installed in the shallow surface soils, typically eight to 12 inches below finished grade.

(rr) Supplemental treatment means a device or system used in an OWTS to perform additional wastewater treatment functions, beyond primary treatment, and capable of reliably producing wastewater effluent of secondary quality or better, prior to discharge to the dispersal system. For the purposes of this Chapter, secondary quality is defined as effluent meeting 30-day average concentration limits of 30 mg/L for biochemical oxygen demand and 30 mg/L for total suspended solids.

(ss) SWRCB OWTS Policy means the Water Quality Control Plan 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.

(tt) 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.

(uu) Waste discharge requirements (WDR) means an operation and discharge permit issued for the discharge of waste pursuant to Section 13260 of the California Water Code.

(x) Wastewater maintenance provider means a person capable of inspecting, monitoring, and maintaining an OWTS in accordance with the provisions of this Chapter, and meeting minimum qualifications as established by the Director.

(ww) 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. NS-517.85, § 2, 11-26-13; Ord. No. NS-300.1002, § 15, 10-21-25)