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Standards and Procedures for the Repair and Upgrade of Septic Systems
INTRODUCTION
This document presents the standards and procedures to be followed in repairing a septic system in Santa Cruz County, including upgrades of existing systems to meet the septic system requirements for building additions and remodels. It is intended for use by contractors, consultants and property owners and applies to residential and commercial properties that are already developed. The requirements, procedures and guidelines contained herein are based on Chapter 7.38 of the Santa Cruz County Code and this document is specifically prepared pursuant to section 7.38.095.E. Parcels that have new development served by a septic system that was installed according to the requirements in Chapter 7.38 that became effective December 10, 1992, shall be ineligible to utilize the allowances for repairs described in Section 7.38.095.B for the purposes of upgrading the system to allow bedroom additions or additions of more than 500 square feet. Systems on parcels that were developed after September 16, 1983 must comply with the provisions of the Regional Water Quality Control Board's Basin Plan (Resolution 83-12).
REPAIR PROCEDURES
The process for repairing or upgrading a septic system involves:
1. Design of a septic system that complies with the requirements presented below. If a property owner desires to design their own septic system, they are urged to contact licensed contractors, septic system consultants or the Environmental Health Service (EHS) for information on soil types and water table levels in their area.
2. Submittal of the permit application and design for review by the EHS Specialist. Significant changes may be required in order to meet the requirements specifically applicable to the property. Soils, percolation and winter water table observation tests may be required to receive approval of the permit. Modification of the original design may be required if site conditions warrant changes.
3. Construction of the system may only begin after approval of the permit is given by the Environmental Health Specialist. 24 hours notice must be given to the Specialist prior to commencing work. Failure to comply may result in issuance of a stop work order and rendering the permit null and void.
4. Installation of the septic system must be done with inspections by an Environmental Health Specialist including a final inspection and permit sign-off.
Since the septic system design initially proposed by an owner or contractor may differ from the design ultimately approved by the Environmental Health Service, it is recommended that any contract between a property owner and a contractor reflect that possibility. When getting bids, property owners should make sure that contractors are bidding on the same septic system design (getting bids on an approved septic permit will ensure this).
TYPES OF SYSTEMS AND ALLOWABLE BUILDING IMPROVEMENTS
Six primary types of septic systems are recognized, depending on the history of the system, the
characteristics of the property, and the desires of the owner to upgrade the structures. If a parcel
cannot meet the requirements for a Standard System, a proposal for a Nonstandard System must
be submitted. Additional requirements are also specified for large systems and systems in sandy
soils.
1. A Standard System meets all of the standard requirements and enables building additions consistent with the number of bedrooms for which the septic system is sized, and consistent with building and zoning department regulations. No construction may occur over the septic system and/or expansion area.
2. Nonstandard Systems do not meet all the requirements for a standard system, but they do meet the more specialized requirements for the different types of nonstandard systems. Approval of a nonstandard system requires recordation of a notice of nonstandard system on the deed, special operating requirements, and payment of an annual inspection fee to confirm continued satisfactory performance (fee waived for Limited Expansion Systems). Five types of nonstandard systems are recognized:
a. An Alternative System utilizes a specific alternative technology to meet requirements and may enable bedroom and other additions if the proposed system design can accommodate the wastewater peak flow.
b. A Limited Expansion System is a permitted system repair that meets all of the requirements for a standard system except for groundwater separation (at distances over 250 feet from a waterbody), or expansion area. Use of a Limited Expansion system requires water conservation measures and enables only a one time addition of up to 500 sq.ft. of conditioned space with no bedroom additions, and no increase in the volume of wastewater discharge. Additions will not be approved which encroach on the septic system or any area of the property needed to install a replacement system which meets the requirements for a standard system to the greatest extent possible. As long as the system performs well, no annual inspection fee will be charged.
c. A Low-Flow System is a permitted system repair that meets all of the requirements for a standard system except for leachfield area or size of pump chamber for pump up systems. Use of a Low-Flow system requires water conservation measures and enables only a one time addition of up to 500 sq.ft. of conditioned space with no bedroom additions, and no increase in volume of wastewater discharge. Additions will not be approved which encroach on the septic system or any area of the property needed to install a replacement system which meets the requirements for a standard system to the greatest extent possible. An annual inspection fee will be charged on the tax bill.
d. A Haulaway System is a system that requires that effluent be pumped out on a seasonal or full time basis to prevent failure, and/or ensure that requirements for groundwater separation are met. Use of a haulaway system enables only a one time addition of up to 500 sq.ft. of conditioned space with no bedroom additions or increase in volume of wastewater discharge. An annual inspection fee will be charged on the tax bill.
e. An Enhanced Treatment System is a system that utilizes special designs and/or additional technology to treat the effluent to a much higher level than a conventional system. The goal is to reduce BOD, Suspended Solids and Nitrogen each to less than 10 mg/l. (In the interim, technologies which meet the objective for BOD and Suspended Solids and provide at least 50% nitrogen removal may be accepted. In sandy soils, special designs which promote denitrification in or under the leachfield will also be considered.) Enhanced Treatment systems will be Alternative Systems and may utilize higher application rates in the leachfield design if they meet the objectives for BOD and Suspended Solids removal (see Section II.D). Enhanced treatment systems are required in the following circumstances:
(1) For systems in Sandy Soils in the San Lorenzo Watershed and Water Supply Watersheds. Reference maps are maintained at the EHS office. Sandy soils are those soils identified by the US Soil Conservation Service as Zayante or Baywood Series, or other soils found in the field to have percolation rates faster than 6 MPI). Enhanced treatment shall be required for any new system and any system which will serve a bedroom addition, a remodel adding more than 500 square feet, or other expansion of use which will result in an increase in volume or strength of wastewater flow. Ultimately, enhanced treatment will likely be required for all repairs in sandy soils.
(2) For Large Systems which serve more than 5 residential units or which have peak daily flows greater than 2500 gallons per day and are located in the San Lorenzo Watershed or a designated Water Supply Watershed. For all new or replacement systems in the designated areas, enhanced treatment shall be required.
(3) A Prestandard System is an existing septic system installed prior to 1993 which shows no indication of failure, but which does not meet requirements for a standard system. Without any further upgrade (but with a satisfactory septic pumpers inspection report), such a system enables only a one time addition of up to 500 sq.ft. of conditioned space with no bedroom additions or increase in volume of wastewater discharge. Additions will not be approved if they will encroach on the septic system or any area of the property needed to install a replacement system which meets the requirements for a standard system to the greatest extent possible.
Standard System
The requirements for new individual onsite wastewater disposal systems as set forth in Chapter 7.38 of the County Code and in the Water Quality Control Plan for the Central Coast Basin shall be met to the greatest extent possible for all system repairs and upgrades. At a minimum, the following requirements shall be met.
A. SEPTIC TANK REQUIREMENTS
1. Tank Size - For residences with 1 to 4 bedrooms, tank size shall be 1500 gallons, with an additional 250 gallons per bedroom for each bedroom in excess of 4.
For commercial or institutional sewage disposal systems, the septic tank volume (independent of any grease traps required) shall be three times (3x) the peak daily flow. When repairing or upgrading commercial or institutional septic systems, the applicant must present at least two years of past water use records and/or a plausible projection of future peak daily wastewater flows.
Exterior grease traps, sized and installed to conform to EHS policy, shall be required on commercial/institutional facilities discharging grease laden waste. The pumping of grease traps as often as necessary to prevent grease entering the leachfield(s) shall be a condition of any food facility Health Permit.
2. Tank Type - Concrete, fiberglass and polyethylene septic tanks from approved manufacturers are the only septic tanks permitted for tank replacements. Existing, two chambered redwood fiberglass, or concrete septic tanks 800 gallons or larger that are in good condition do not require replacement at the time of septic system repair and will be recognized as passing an inspection for loan review purposes. Other tank types may be allowed provided adequate documentation of satisfactory performance is provided.
3. Access to Tank - Septic tanks should be installed within 12 inches of the ground surface when possible. If it is demonstrated that the building sewer pipe cannot be modified and the top of a septic tank must be deeper than 12 inches from the ground surface, the tank shall be modified so as to extend all manholes and covers to a minimum of 12 inches from the ground surface. Material used to extend the manholes and covers shall be of the same material as the septic tank. Septic tanks placed in paved driveways shall be provided with "traffic grade" concrete access manholes with cast iron lids. A cleanout to finished grade shall be provided between the building and the septic tank. 3" or 4" Schedule 40 ABS pipe shall be used to connect the building drains to the septic tank.
4. Setbacks for Tank Installation - Septic tanks shall be installed to conform to the following minimum setback distances:
From Septic Tank To: Minimum Distance in Feet:
Leaching Device 3
Property Line, Easement or Right-of-Way 5 Foundations, Structures, Decks 5 Water Line 10 Stream, Well, Spring, Watercourse 50 5. Water Tight Tanks - For all repairs in areas of suspected high groundwater and/or utilizing pumps, water tight tanks and risers shall be required. Water tightness shall be ensured by filling the tank and riser with water and observing that the level does not drop by more than 1/4 inch in 12 hours. Plastic tanks will not be allowed in suspected high groundwater areas unless provisions approved by the manufacturer are made to prevent the tank from floating or collapsing when pumped during conditions of high groundwater.
B. LEACHFIELD REQUIREMENTS
1. GENERAL - The function of the leachfield is to dispose of the clarified wastewater from the septic tank into the ground. The relevant factors in designing a leachfield are: The depth from the surface of the ground to the water table (especially during the rainy season), the ability of the soil to soak up the water from the leachfield (percolation rate) and, the amount of land available on the subject parcel to install the leachfield. The following subsections list the requirements and procedures to be followed in designing a leachfield.
2. AMOUNT OF LEACHFIELD REQUIRED - Residential
The following table presents the minimum amount of leachfield required for residences per dwelling unit.
LEACHING AREA REQUIREMENTS - SQ. FT.
PERCOLATION RATE - MPI* MAXIMUM WATER USE*To the nearest whole MPI (Minutes Per Inch)
1-5 6-30 31-60 61-120 (APPROX. GAL/DAY) 1 Bedroom 500 600 900 2150 215 2 Bedrooms 625 750 1125 2700 270 3 Bedrooms 750 900 1350 3250 325 4 Bedrooms 875 1050 1575 3750 375 Additional Bedrooms 125 150 225 ea. ea. ea. 550 55
a. Determination of Soil Percolation Rate - The percolation rate range of the soil shall be estimated (if not already established by percolation tests) by the applicant on the application form for the purposes of estimating the proposed leachfield area required for the number of bedrooms desired. After the application is made, the parcel's soil types taken from the Soil Survey of Santa Cruz County will be noted by EHS staff on the application check sheet. A field visit to the parcel will be made by the EHS Specialist. A test hole excavation to observe soil texture characteristics (as well as a check for water table level) may be required. A percolation rate range will be assigned to the soils by the EHS specialist based on the Soil Survey and soil textures observed at the site. If concurrence on the estimated percolation rate range of the soil cannot be achieved among the inspector and the owner/contractor/consultant, a percolation test shall be performed by a licensed consultant or contractor familiar with the Santa Cruz County percolation test requirements. The results of the percolation test shall then be the basis for determining the leachfield area required.
b. Effective Leaching Area - The size of the leachfield is determined by the total of the areas of the trench bottom and sidewalls beneath the leach pipe. Example: A trench that is four feet deep, 1 ½ feet wide and 50 feet long with the leach pipe on top of 2 ½ feet of drain rock, has an effective leaching area of 325 sq. ft. There are 6 ½ sq. ft. (2 ½ + 1 ½ + 2 ½) of leaching area per lineal feet of trench:
6.5 sq. ft. per lineal ft. X 50 ft. = 325 sq. ft.
c. Expansion Area - In order to meet the requirements for a Standard System, a reserve expansion area for future leachfield repairs on the parcel must be designated on the approved plot plan for the septic system design. This expansion area must be capable of accommodating a duplicate of the approved leachfield. No construction of buildings, permanent swimming pools or other permanent structures shall be permitted over the expansion area.
3. AMOUNT OF LEACHFIELD REQUIRED - COMMERCIAL/INSTITUTIONAL
The requirements for existing commercial/institutional establishments shall be determined based on an analysis of peak daily loading rates, using an absorption rate of 0.43, 0.36, 0.24 and 0.10 gallons per square feet of leaching area per day for soils percolating in the ranges 1-5, 6-30, 31-60 and 61-120 MPI, respectively. The applicant shall present at least two years of past water use records and a plausible projection of future peak daily wastewater flows if a change in property use which could result in increased wastewater loading is proposed.
Note: For all large systems serving more than 5 residential units or having peak daily flows greater than 2500 gallons per day that are located within the San Lorenzo Watershed or a water supply watershed, enhanced treatment systems will be required. These systems will be considered Alternative Systems and can utilize increased application rates in the leachfield design (see Sections II.D and II.E).
4. LEACHFIELD CONSTRUCTION REQUIREMENTS FOR STANDARD SYSTEMS
Following are the requirements for a Standard Septic System. Owners of parcels that cannot accommodate all of the requirements of this section should refer to the Nonstandard System sections below. Please see Appendix A for a diagram of a standard leachfield.
a. Allowable Soil Percolation Rates
Soils in which the leachfield is constructed must percolate in the range of 1-120 MPI. Please see section B.2.a above for a description of the process to determine percolation rate range.
Note: For systems in sandy soils (those identified by the Soil Conservation Service as Zayante or Baywood Series, or any other soil with fast percolation rates between 1 and 5 MPI) enhanced treatment will be required within the San Lorenzo Watershed and designated Water Supply Watersheds for any new system or any system serving a bedroom addition, a remodel adding more than 500 square feet, or other expansion of use which will result in an increase in volume or strength of wastewater flow. Such systems will be Alternative Systems and can utilize increased application rates in the leachfield design (see Sections II.D and II.E)
b. Groundwater Separation Below Leachfield
The minimum separation between the bottom of any leaching device and seasonally high groundwater shall be:
5 feet where the leaching device is between 50 and 100 feet from a stream, spring, or other waterbody.
3 feet where the device is over 100 feet from a waterbody.
(At distances greater than 250 feet from a waterbody, a system with groundwater separation below the leachfield less than 3 ft. may be approved as a Limited Expansion System provided however that a separation of at least 1 ft. must be maintained for at least 90% of the year. This will be considered a Limited Expansion System for the purposes of building additions, but will not be subject to annual inspections and an annual fee.)The definitive determination of depth to groundwater in the area where a leaching device is proposed shall be through observation of depth to groundwater by the EHS Specialist in a test hole excavation (or monitoring well) during the wet weather testing period as described in Section 7.38.120.B. During the rest of the year, the depth to groundwater will be estimated based on observation of test hole excavations and groundwater records maintained by the EHS.
c. Trench Depth
The standard trench depth shall be a maximum of 4 feet from the ground surface (2 ½ feet maximum effective depth). Parcels with soils that percolate in the range 6-60 MPI may use a deeper trench to a maximum of 6 ½ feet from the ground surface (5 feet maximum effective depth) if space on the parcel prevents the use of a standard trench depth. Parcels that have surface soils that percolate slower than 60 MPI and deeper soils that percolate faster than 60 MPI may use a deeper trench but shall only receive credit for the area of the trench in the acceptable percolation rate range. However, in all instances where a trench deeper than 4 feet is utilized, the trench shall be as shallow as possible using the maximum lineal feet that can fit on the parcel while still reserving the required expansion area.
d. Credit for Existing Trenches Deeper than Standard Trenches
When upgrading a septic system, credit shall be given for any functioning, existing trenches, as verified by a licensed septic pumper's report, that meet all of the requirements herein, with the possible exception of trench depth. Deeper trenches may be allowed where the soils percolate in the range 6-60 MPI. Where the soils percolate in the range 1-5 MPI, no exception to the 2 ½ feet effective trench depth for existing trenches shall be given unless treatment for nitrogen removal (such as a sand filter or other approved treatment) is provided. This must be done through the procedures for a Nonstandard System, as described in Section II.
e. Trench Width - Trenches shall be 18" to 36" in width. The trench bottom area plus the areas of the two sidewalls beneath the leach pipe is the effective leaching area (see section B.2.a above).
f. Maximum Slope - The maximum slope where leachfields may be approved is 30%, except that leachfields may be approved on slopes up to 50% under the following conditions: the leach pipe must be buried at least 2 feet, there must be at least 5 feet of soil percolating in the range of 1-120 MPI below the leachfield, and conditions must otherwise be suitable to prevent lateral surfacing of effluent.
g. Minimum Trench Spacing - The minimum spacing between trenches (edge to edge) shall be twice the effective depth to a maximum of 10 feet. h. Trench Setbacks - The minimum setback requirements between a leachfield and the following are:
Septic tank 3 feet Property line 5 feet Foundations/decks 5 feet Potable water pipe 10 feet Well 100 feet Embankment greater than 67% 2 times the height up to 25 feet; if an impermeable layer is encountered, setback shall be 4 times the height up to 50 ft. Stream, spring, waterbody 100 feet if space permits but no less than 50 feet. Seasonal drainageway 25 feet (flows no more than one week after significant rainfall)
Swimming pool 10 feet i. Trench Construction Details
General installation guidelines: The leach trench shall be excavated to the appropriate depth perpendicular to any slope, following the contour of the land so as to maintain the same trench depth for the length of the trench. Any smeared trench sidewalls shall be raked to roughen the surface to enhance percolation. The trench inspection riser pipe shall be placed vertically in the end of the trench and held in place vertically while the clean drain rock is placed in the trench. The top of the bed of rock and the leach pipe shall be leveled using a builders level or transit.
The leach pipe shall be placed on the level rock bed with the holes pointed down and a cap placed over the end of the pipe. When the pipe is level, drain rock shall be brought up to 2" in depth over the drain pipe. The perforated inspection riser pipe shall be cut to the rock level and a section of solid pipe attached to extend through the ground surface. Untreated building paper or straw shall be placed over all of the rock surface of the leachfield. Earth backfill shall be placed over the leachfield 8" - 12" deep, and shall be mounded to ensure drainage away from the trench. If settlement occurs after installation, additional backfill must be added. The inspection riser pipe shall be capped. Any disturbed soils shall be protected from erosion by mulching with straw and seeding with erosion control seed mix.
Additional Construction specifications are as follows:
Maximum length of trench 100 feet Slope of leach pipe should be level, but 3" in 100 ft maximum Rock over pipe 2" thick Size of Rock ½" - 2 ½" washed drain rock - dirty loads will be rejected
Type of leach pipe 3" or 4" coextruded styrene pipe j. Trench Bottom Setback to Impermeable Rock or Soil Layer - There shall be at least 5 feet of soil that percolates in the range 1-120 MPI beneath the leachfield if a stream, spring, or cutbank is located within 50 feet, or 3 feet of permeable soil if the horizontal separation is more than 50 feet.
k. Trench Inspection Riser Pipes - Each distinct leach trench shall have a pipe placed vertically in the end of the trench to provide a means of monitoring the water level in the leachfield. The pipe shall be a perforated pipe that transitions to solid pipe at the top of the rock before exiting the ground. The pipe shall be extended to the bottom of the trench and held in place vertically while the rock is placed in the trench. A cap or female adapter with a threaded plug shall be provided at the end of the pipe. Concrete boxes with lids shall be provided around the pipe end where a flush to grade pipe end is desired.
l. Distribution of Effluent to Multiple Trenches - When there is more than one leach trench, an approved effluent distribution device shall be used to distribute effluent to each trench (see Appendix B for details). "Pop-over" distribution is not permitted.
m. Geological Hazards - Where there is local evidence of, or a history of, landslide activity, the EHS Specialist may require a geologic hazards assessment to ensure that any proposed leachfield will not contribute to a slope failure. The Planning Department technical review staff shall review and provide comment on all such required technical reports which address potential impacts on slope stability from proposed septic systems to serve new or existing development. The applicant shall pay a fee for such review as established by the Board of Supervisors.
n. Sewage Easements - Locations on nearby properties or right-of-ways may be used for sewage disposal for system repairs only, if a recorded easement is obtained according to specifications in Section 7.38.060. No increase in bedrooms shall be approved if an easement is needed for sewage disposal.
o. Leachfield Repairs and Upgrades in Floodplains or Floodways - Leachfield repairs may be permitted for parcels in floodways. Upgrades to support building additions are not permitted in the floodways.
p. Drainage Improvements - Roof drains and surface runoff shall be directed away from the disposal area so as to reduce soil saturation.
q. Site Restoration and Erosion Control - At the completion of the job, the site must be restored, with proper, stable disposition of excavated material and measures taken to prevent any significant erosion of surfaces disturbed during installation of the system.
5. EFFLUENT PUMPING
When effluent pumping is necessary to deliver the effluent to the leachfield, a 1000 gallon effluent pumping station tank shall be provided. The pump control switches shall be set so that 750 gallons of emergency storage is available during power outages. Pump controls shall also be installed to limit the amount of effluent that can be pumped to the leachfield in one day to 120% of the daily design flow so as to prevent overloading the leachfield after an extended power outage. Any pump up system which has less than 300 gallons storage capacity in the pump chamber shall be considered a Low-Flow System. A system with 300-750 gallons storage capacity shall be considered a Limited Expansion System. A handout is available from EHS that describes the detailed effluent pumping requirements.
6. SEEPAGE PITS
The use of seepage pits to repair or upgrade a septic system for the purposes of bedroom additions shall only be permitted where there is a previously installed seepage pit and all of the soil, groundwater and other setback requirements above are met. However, if there is room to accommodate a standard leachfield, that shall be the preferred leaching device. Seepage pits must meet Basin Plan requirements. On parcels where a seepage pit has not been installed in the past, and standard leachfields cannot be installed, seepage pits may be installed provided they meet the requirements contained in the Regional Board's Basin Plan. In this instance, no bedroom increases shall be approved.
7. GRAVELLESS LEACHFIELDS
The use of gravelless leachfields may be permitted as provided in the chamber leaching regulations promulgated by the Health Officer. However, all standards regarding the location and placement of leaching devices shall apply to the gravelless method of effluent disposal.
C. WATER CONSERVATION
Water conservation devices are recommended to be installed in any home or building served by an onsite wastewater disposal system. All Limited Expansion, Low-Flow, and Haulaway Systems are required to install water conservation devices as a condition of any permit issued. See section II.A.1 below for recommendations.
D. GREYWATER DISPOSAL
1. Greywater is defined as any wastewater from washing machines, dishwashers, bathroom lavatory sinks, and/or showers. Greywater may contain pathogens and nuisance substances and shall not be discharged directly onto the ground surface.
2. Greywater shall be discharged to the septic tank system or to an approved disposal device.
3. If the septic system is inadequately sized or performs unsatisfactorily due to surcharge of greywater, the greywater may be discharged to a separate disposal device approved by EHS. If the kitchen sink is connected to the greywater disposal system, a small, two chambered tank shall be provided. The greywater disposal device shall be constructed according to the following minimum requirements:
setback from leachfield - 10 feet
setback from stream - 25 feet
tank size - 3 times expected daily flow
leaching device size - 200 sq. ft. sidewall area or as calculated based on loading rate of 1 gal./sq.ft./day; for clothes washers only, a minimum size of 104 sq. ft. sidewall area (96 cubic foot volume) is allowed.
minimum cover - 8 inches
maximum depth - 5 feet
groundwater separation - 1 foot 90% of the year if stream setback is greater than 100 ft.; 3 ft. if stream setback is between 25 and 100 ft.
4. A minor sewage disposal permit, at a reduced fee, is required for installation of a greywater sump.
E. CURTAIN DRAINS
A permit shall be required for any curtain drain installed within 100 ft. of a leachfield. Curtain drains located down gradient from a leachfield must be at least 25 feet from the leachfield. If an impermeable layer is present or soils percolate faster than 1 minute per inch, curtain drains must be located at least 50 feet away. Curtain drains located upgradient of a leachfield must be installed with the bottom of the drain higher in elevation than the top of the leachfield, or must be located at least 25 feet away. Curtain drains shall not be placed in a location that will render any necessary expansion area unusable on the site or an adjacent parcel. Curtain drains shall not be permitted for the purposes of attempting to lower groundwater levels to meet the required setback to groundwater from leaching devices for new development or expansion of existing development.
Nonstandard Systems
If a parcel cannot meet all of the requirements for a Standard System described in Section I above, septic system repairs must be made using a Limited Expansion System, a Low-Flow System, Haulaway System, Alternative System, or Enhanced Treatment System. All of these are considered Nonstandard Systems. Parcels with Limited Expansion, Low-Flow, or Haulaway Systems cannot receive approval for building permits to add more than a one time addition of up to 500 sq. ft. of conditioned floor area that does not increase bedrooms or discharge. Under many circumstances, the conditions which prevent a parcel from meeting requirements may be overcome using an Alternative system and in that case bedroom additions may be allowed (see section II.D). Systems for parcels with soils that percolate faster than 1 MPI or slower than 120 MPI can only be approved if an acceptable proposal is submitted that complies with the requirements in the Alternative Systems section (Section II.D).
Parcels served by nonstandard systems are subject to recordation of a notice of nonstandard system and payment of an annual charge to cover the cost of inspection and monitoring of system performance, as discussed below under Section E.
A. LIMITED EXPANSION SYSTEMS
Limited Expansion Systems are conventional systems which meet all requirements except for any one of the following:
Groundwater separation below the leachfield is between 1 and 3 feet at least 90% of the year and the system is over 250 ft. from a waterbody.
Less than 100% expansion area is available.
Water conservation measures must be installed, as specified below under Low-Flow Systems. All other Nonstandard system requirements must be met, except that the annual inspection fee will be waived if there is no indication of system problems.
B. LOW-FLOW SYSTEMS
Low-Flow Systems are conventional systems which meet all requirements except for any one of the following:
-
Only 50-99% of the required amount of leachfield area can be installed.
-
The system requires effluent pumping, but the pump chamber is less than required size.
Owners of parcels that elect to apply for a permit to install a Low-Flow System shall submit a proposal to install as much leachfield as possible that meets the requirements in section I.B.4 above. A permit for a Low-Flow system can only be approved if at least 50% of the leachfield
required for a Standard system can be installed. A proposal for an Alternative system or Haulaway System must be submitted by the owner if less than 50% of the required leachfield can fit on the parcel.
The following water conservation measures and provision for seasonal haulaway shall be made part of all Low-Flow System proposals.
1. Water Conservation Measures Required - All proposals for Limited Expansion and Low-Flow Systems shall include a requirement to install the water conservation devices described below if they are not already installed. These devices must be installed and inspected prior to permit final sign off.
a. All toilets shall be 1.6 gallon, or less, flush toilets.
b. Low flow shower heads of 2.5 gallons per minute, or less, shall be installed in all showers.
c. Water conservation aerators shall be installed on all lavatory, kitchen sink, and other household faucets.
d. Garbage grinders shall be removed.
2. Seasonal Haulaway Required as Necessary to Prevent System Failure -
All proposals for Low-Flow systems shall include a requirement that the septic tank will be pumped as necessary to prevent any failure or overflow of the septic system. A gate valve on the septic tank effluent pipe is required to be installed prior to final inspection. This valve will prevent wastewater from escaping from the tank and will also prevent groundwater from entering the tank. If the existing septic tank allows groundwater to leak into the tank, a watertight septic tank shall be installed. A violation reinspection fee will be assessed if the system is observed to fail.
C. HAULAWAY SYSTEMS
Where less than 50% of the leachfield required in section I.B.2 can be installed on a parcel where the existing wastewater disposal system is failing or intermittently failing, a Haulaway System shall be utilized. Extreme water conservation measures should be utilized by the resident. Ultra low-flow toilets (0.5 gallons or less per flush) will be required. A watertight holding tank shall be installed if the existing septic tank cannot be made watertight. A holding tank high water warning alarm shall be installed. Any available leaching area may be used for greywater disposal if greywater disposal requirements are met. All blackwater effluent must drain to the holding tank. Blackwater may be discharged to the leachfield during periods when groundwater separation requirements are met. Risers must be installed in the leachfield and in the vicinity of the leachfield to monitor groundwater level. Records of septic tank pumpings must be made available for inspection purposes.
D. ALTERNATIVE SYSTEMS
The owner of a parcel that cannot meet the requirements for a Standard System has the option described above to utilize a Limited Expansion, Low-Flow, or Haulaway System. However, if those options are selected, building additions are quite limited due to the limited sewage disposal capacity of the parcel. The resident may incur considerable cost and inconvenience due to the substandard system and the requirement for seasonal haulaway. The Alternative system program permits the use of various wastewater treatment and disposal technologies that are not specifically described in Chapter 7.38 of the County Code. The design, installation and use of alternative treatment and disposal technologies may result in superior wastewater treatment and disposal for that parcel and may, depending on site specific conditions, permit building additions beyond that permitted for other Nonstandard Systems.
The following is a discussion of the alternative technologies currently approved for use in Santa Cruz County. Information is given regarding design and construction requirements for each of these technologies. A listing of the possible applications of each technology is presented subsequently.
1. APPROVED ALTERNATIVE TECHNOLOGIES (Detailed specifications for all these technologies are available in the Environmental Health Office.)
a. MOUND SYSTEMS
A mound system consists of a mounded leaching bed constructed above ground that receives effluent distributed over the entire bed by means of pumped pressure distribution piping system. Use of this type of system is suited for gently sloping parcels subject to prolonged periods of shallow groundwater. For septic system repairs or upgrades, the following specifications are required: The minimum mound body fill depth shall be 2 feet below the distribution bed. Minimum depth from the distribution bed to groundwater shall be 3 feet (5 ft. within 25-100 ft. of a waterway). Minimum depth from natural grade to impermeable strata shall be 2 feet.
b. SAND FILTER
Sand filters provide treatment of the septic tank effluent in order to maximize the application rate of effluent where leachfields are constructed in slowly percolating soils. Sand filters provide denitrification of septic tank effluent, and their use prior to effluent disposal in rapidly percolating sandy soils may reduce nitrate discharge by at least 50%, if designed and operated properly. Increased effluent treatment provided by sand filters also allows a reduction in the required groundwater separation to 1 foot and allows reducing leachfield size by 50% from the requirements for a Standard System.
c. OTHER ALTERNATIVE SYSTEMS
Designs for alternative wastewater treatment and disposal technologies other than those mentioned above may be considered for approval as described in Section 7.38.182 of the County Code.
2. APPROVED APPLICATIONS OF ALTERNATIVE WASTEWATER DISPOSAL TECHNOLOGIES
a. INSUFFICIENT LEACHING AREA
Whenever a parcel cannot accommodate the size of leachfield required by the soils found on the parcel, a sand filter may be used to increase the soil application rate for wastewater loading. The leachfield requirements listed in section I.B.2 may be reduced by 50% when a sand filter is used. Similarly, the application rates for commercial or institutional properties may be reduced by 50% by the treatment of septic tank effluent with a sand filter (grease traps may also be required for commercial/institutional parcels - see section I.A.1).
b. SOIL PERCOLATION RATES SLOWER THAN 60 MPI
For soils percolating 60-120 MPI, the use of a sand filter or approved enhanced treatment system may permit the use of leachfields sized according to the requirements for 31-60 MPI soils. Additionally, leachfields may be installed deeper than 5 feet effective depth to a maximum of 10 feet effective depth provided that all setbacks are observed and the leachfields are installed as shallow as possible.
Soils that percolate slower than 120 MPI shall not be approved for leaching devices and must propose a haulaway system as described below.
c. SETBACK TO GROUNDWATER UNSUITABLE FOR LEACHFIELDS
Parcels that have gentle slopes and groundwater problems that prevent the use of conventional leachfields may be suitable for mound systems described above. A proposal for a mound system that meets requirements for the design loading rate may enable bedroom and other building additions provided that an area is available for replacement of the mound. Use of a sand filter or approved enhanced treatment system may also allow building additions with reduced groundwater separation.
d. ENHANCED TREATMENT - An Enhanced Treatment System is a system that utilizes special designs and/or additional technology to treat the effluent to a much higher level than a conventional system. The goal is to reduce BOD, Suspended Solids and Nitrogen each to less than 10 mg/l. (In the interim, technologies which meet the objective for BOD and Suspended Solids and provide at least 50% nitrogen removal may be accepted. In sandy soils, special designs which promote denitrification in or under the leachfield will also be considered.) Enhanced Treatment systems will be Alternative
Systems and may utilize higher application rates in the leachfield design if they meet the objectives for BOD and Suspended Solids removal (see Section II.D). Enhanced treatment systems may be used to treat effluent where soils percolate in the range of 60-120 MPI; they are required in the following circumstances:
(1) For systems in Sandy Soils in Water Supply Watersheds. Sandy soils are those soils identified by the US Soil Conservation Service as Zayante or Baywood Series, or other soils found in the field to have percolation rates faster than 6 MPI. In these soils, enhanced treatment shall be required for any new system and any system which will serve a bedroom addition, a remodel adding more than 500 square feet, or other expansion of use which will result in an increase in volume or strength of wastewater flow. Ultimately, enhanced treatment will likely be required for all repairs in sandy soils.
(2) For Large Systems which serve more than 5 residential units or which have peak daily flows greater than 2500 gallons per day and which are in the San Lorenzo Watershed or a designated Water Supply Watershed. For all new or replacement systems in designated areas, enhanced treatment shall be required.
E. NONSTANDARD SYSTEM REQUIREMENTS
The approval and use of a nonstandard system is subject to the "Procedures for Approving and Managing Nonstandard Sewage Disposal Systems" (Sewage Policy 16). These procedures are summarized below:
1. Acknowledgment of Requirements for Use of a Nonstandard System - Prior to approval of the permit application for a nonstandard system, the property owner must sign an Acknowledgment of Requirements for Use of a Nonstandard System prepared by EHS staff, in which the owner acknowledges and agrees to comply with all requirements for use of the nonstandard system, including: limitations on property use and water use, operation and maintenance requirements, recordation of a Notice of Nonstandard System on the property deed, annual compliance inspections by the County, and payment of an annual service charge on the property tax bill to cover the costs of inspections. The executed Acknowledgment and Requirements are attached as conditions of approval of the permit and continuing use of the system.
2. Notice of Nonstandard System - Once the nonstandard system is installed, the County shall record a Notice of Nonstandard System on the deed for the affected parcel. This will describe the type of system and its limitations (if any) and specify operating conditions, including annual reinspections by EHS of the system. This will replace the past procedure of requiring an operating permit for alternative systems.
3. Annual Inspection Fee - Property owners of Nonstandard systems that require annual reinspections by EHS personnel to insure correct system operation will be subject to an additional CSA 12 service charge on their property tax bill to pay for the cost of the inspections.
Enforcement
If any of the terms or conditions of an approved sewage disposal permit are not observed during the installation or operation of any septic system, and the owner fails to correct the problem after reasonable notice, the following enforcement action(s) may be exercised.
A. VIOLATION REINSPECTION FEE
When a violation of requirements has been duly noticed to the owner of the parcel, any subsequent enforcement visits to the parcel shall cause a violation reinspection fee to be imposed for each visit to the parcel as authorized by Section 7.38.290 of the County Code.
B. NOTICE OF VIOLATION
A notice of violation describing the violation of the standard(s) contained in this document or in Chapter 7.38 of the County Code may be recorded against the parcel until the violation is abated.
C. REVOKING OF CONTRACTOR PERMIT PRIVILEGES
If an individual contractor violates the requirements of this document or Chapter 7.38 of the
County Code, a complaint will be filed with the State Contractor's Licensing Board.
APPENDIX B
December 30, 1992
SEPTIC TANK EFFLUENT DISTRIBUTION BOXES
Installation Procedure and Approved Models
A distribution box is used to divide the effluent flow from a septic tank into two or more leach tenches for soil absorption. Equal distribution is very important in order to take advantage of all of the available leaching area. Spreading the effluent dose over all parts of the system maintains a relatively low soil loading rate and provides better effluent treatment. Distribution boxes also provide a readily accessible means of locating the leaching device, making flow adjustments as needed, monitoring the disposal system, and making additions to the system.
Distribution boxes are typically made of reinforced concrete with plumbing "knock outs" into the box. The inlet must be higher than the outlets, with all outlets at the same level. The box must be large enough to accommodate the pipes and fittings used and still allow for flow adjustment. A sturdy gas-tight lid (and risers where appropriate) shall be provided that permits access from the surface. A list of approved manufacturers and distribution box model numbers is presented below.
The correct installation of distribution boxes requires proper planning and careful construction techniques. The location of the box(es) and associated plumbing, as well as the required elevations, must be worked out in advance. Grading of all portions of the system must be done with care such that the leach trench maximum allowable depth may be maintained. The distribution box(es) must be "wet set" on a pad of cement or grout on level undisturbed or mechanically compacted soil. All the outlet plumbing must be set into the box as level as possible with final flow adjustments made prior to final backfill. All piping must be resealed with grout. Environmental Health Service staff must perform an inspection that demonstrates that the flow out of the box has been properly adjusted as part of construction inspection for final system approval. Adequate water must be available at the site for the flow test.
Fine adjustments of flows to each leachfield shall be made as necessary to maintain the proper function of the distribution box. If any leachfield fails, a valve must be installed on the pipe from the distribution box to the leachfield and closed to stop the failure.
APPROVED EFFLUENT DISTRIBUTION DEVICES
MANUFACTURER
| M. C. Nottingham | Models: | D-48 (5 exit ports) |
| D-49 (3 exit ports) | ||
|
| ||
| Tom's Septic Tanks | Septic tank with built-in "D" box | |
| And all separate "D" boxes | ||
| O.S.I. | Hydrosplitter | |
| Zabel | Flow-divider | |
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