ONSITE WASTEWATER TREATMENT SYSTEMS GUIDANCE MANUAL

Fresno County OWTS Guidance Manual (January 2018 version) 1

ONSITE WASTEWATER TREATMENT SYSTEMS GUIDANCE MANUAL

Fresno County Department of Public Works and Planning 2220 Tulare Street Fresno, CA 93721


Manual Introduction This Onsite Wastewater Treatment System Guidance Manual (Manual) provides the procedural and technical details for implementation of the provisions of the Fresno Local Agency Management Plan (LAMP) codified in Chapter 15.20 of the Fresno County General Ordinance Code. The provisions within this Manual are designed to protect public health, groundwater and surface water bodies from degradation and provide safely operating Onsite Wastewater Treatment Systems through proper design, siting, installation, maintenance and monitoring. Onsite Wastewater Treatment Systems (OWTS) as referenced herein, include Onsite Wastewater Treatment Systems as defined by the Water Quality Control Policy for Siting, Design, Operation and Maintenance of Onsite Wastewater Treatment Systems (State OWTS Policy), adopted by the State Water Resources Control Board, and which took effect on May 13, 2013. The Fresno County Department of Public Works and Planning, Development Services and Capital Projects Division, (Department), is the agency responsible for the enforcement of the Ordinance and provisions in this Manual. The California Regional Water Quality Control Board for the Central Valley Region (Regional Water Boards) is the state agency responsible for the protection of groundwater and surface water quality in Fresno County (County). While the Department administers the local program, the Regional Water Boards retain the authority to issue Waste Discharge Requirements for any discharge of wastewater that may affect water quality. The requirements in this Manual shall apply to all OWTS with flows less than three thousand five hundred (3,500) gallons per day (gpd) that accept and treat (1) domestic-strength wastewater or (2) high-strength wastewater from commercial food service buildings with a biochemical oxygen demand (BOD) less than or equal to three hundred (300) milligrams per liter (mg/L) or of total suspended solids (TSS) less than 330 mg/L or a fats, oil, and grease (FOG) concentration less than 100 mg/L. Owners of OWTS that receive high-strength or high-flow wastewater from non-residential facilities other than commercial food service facilities or OWTS that do not comply with the requirements of the Ordinance and this Manual shall notify the Regional Water Board and may be directly regulated by the Regional Water Board through issuance of waste discharge requirements (WDRs) and the Department through approval of design/construction documents and issuance of installation permits. Amendments to the Manual The regular review and update of this Manual is necessary to keep pace with new issues, policies, procedures and technologies affecting the use and management of OWTS. Any substantive changes in requirements will require review and approval by the Central Valley Regional Water Board and adoption by Resolution of the Fresno County Board of Supervisors (Board of Supervisors).

Manual Organization This Manual is intended to provide technical guidance for Department staff, property owners, real estate professionals, consultants and other practitioners that may be involved with the design, installation, repair, modification, operation and maintenance of new and existing OWTS.


This Manual is divided into the following sections:

Onsite Wastewater System Program Overview Page 3

Permitting Process Overview Page 4

Qualified Professional Requirements Page 4

Plan Review and Site Evaluation Requirements Page 5

System Types Page 15

Variances Page 18

Existing OWTS and Bedroom Additions Page 18

Review and Inspection Requirements Page 19

Complaints and Investigations Page 19

Reporting Requirements Page 19

Onsite Wastewater System Overview

An OWTS is an Onsite Wastewater Treatment System that may include tanks, piping, treatment devices, dispersal systems or other components that convey, store, treat and dispose of wastewater. OWTS types include standard OWTS and advanced OWTS as well as individual OWTS and community OWTS. The provisions of this Manual are not intended to prevent the installation of any material or prohibit any design or method of construction not specifically prescribed by this Manual provided that any such alternative has been approved by the Department. An alternative material, design or method of construction shall be approved where the Department finds that the proposed design is satisfactory and complies with the intent of the provisions of the LAMP and that the material, method or work offered is, for the purpose intended, at least the equivalent of that prescribed in this Manual in quality, strength, effectiveness, durability and safety. The Department will only permit Standard OWTS in accordance with the adopted LAMP, any other system types, including advanced systems, shall require review and permitting through the Central Valley Regional Water Quality Control Board (RWQCB).


Permitting Process Overview System Permits and Fees Permits are required from the Department for installation of new, replacement Systems, repair, and modification of existing Systems, demolition and/or decommissioning of abandoned Systems.

Permit Issuance $38.00

Test Hole inspection. $96.00/ Inspection

Septic Tank installation including Seepage Pits or Drainfields $148.50 each

Modification to an existing septic system $90.50

Demolition of an existing septic system $113.25 Land Use, Site Development, and Building Project Requirements Septic system density will be limited to one system per two acres. Any new development of less than two acres or secondary dwelling will require a nitrogen loading analysis by a qualified professional, demonstrating to the Department that the regional characteristics are such that an exception to the septic system density limit can be accommodated. The Department will refer any analysis to the RWQCB for their concurrence and input. Supplemental treatment systems for nitrogen reduction will be referred to the RWQCB for permitting. Interagency Coordination (Development Services, Building, Planning, EH, Code Enforcement, RWQCB) Depending on the type and location of the Onsite Wastewater System or project, the Department may need to coordinate with other local, regional, state and federal regulatory agencies in order to issue approvals and/or permits for a System.

Qualified Professional Requirements

The Department requires that you must work with a Qualified Professional to conduct work and prepare documents for Site Evaluations along with Onsite Wastewater System design, installation, repair, and abandonment. Fresno County Environmental Health also maintains a list of registered Septage Pumpers. A Qualified Professional is defined as one of the following:

a. Department Building Inspectors demonstrating knowledge of OWTS; b. California Professional Engineer; c. California Engineering Geologist; d. California Professional Hydrogeologist; e. Registered Environmental Health Specialist (REHS) f. Soil Science of America Certified Soil Scientists


The Qualified Professional who prepares the Site Evaluation report shall sign the report. Additionally, he/she shall affix a professional stamp on the plot plan and the report adjacent to the signature, acknowledging the responsibility for the overall preparation of the report. A Qualified Contractor is defined as an individual who possesses a valid California License in one of the following classes:

a. Class A - General Engineering Contractor; b. Class B - General Building Contractor; c. Specialty Class C-36 - Plumbing Contractor, or d. Specialty Class C-42 - Sanitation System Contractor

The qualifying contractor licensed within these classifications may perform all work related to installation of new and replaced OWTS, and repair of existing OWTS in accordance with California Business and Professions Code and Title 16 of the California Code of Regulations. A Septage Pumper is a person registered with Fresno County Environmental Health who is qualified to pump and haul waste from septic tanks, cesspools, sewage seepage pits, grease traps and chemical toilets and to the disposal of the cleanings therefrom in territory under the jurisdiction of Fresno County according to the California Health and Safety Code, Division 104, Part 13, Sections 117400-117450.

Plan Review and Site Evaluation Requirements The following project types will require Planning Review and, in most instances, a Site Evaluation. A. Land Development Projects Land Subdivision projects where a public sewer is not available. B. Building Construction Any new construction where a public sewer is not available within 200 feet of the building. C. Building Expansion Any renovation of an existing building that entails expansion beyond the current footprint of the permitted structures. D. Addition of a Building or Structure on the Property The addition of a new building or structure such as a garage, gazebo, patio, deck, ground-mount solar, swimming pool, spa, or driveway, whether or not it includes any plumbing or bedroom equivalents must be evaluated to determine whether the new structure encroaches on the setbacks for the existing system and to ensure that the designated 100% future expansion or replacement area is not impacted. Department staff will make parcel files available for review upon request, and can work with the applicant to make initial determinations on setback compliance.


E. Repair or Expansion

a) Any repair, expansion, or replacement of the septic tank or dispersal system where there are no records of the previous installation.

b) Any repair, expansion or replacement of the septic tank or dispersal system where it is discovered that the existing system is nonconforming and does not meet the current requirements.

c) Any repair, expansion or replacement of a previously approved, existing septic tank or dispersal system where geological conditions have been identified that may adversely affect the operation of the system.

d) If you are rebuilding because of a fire or other natural disaster, the Department can, at its discretion, approve an exception for the repair of an OWTS through the County variance process. A complete Site Evaluation report may be required in order to consider a variance.

F. Activation of the 100% future replacement area The addition of a new building or structure such as a garage, gazebo, patio, deck, ground-mount solar, swimming pool, spa, or driveway, whether or not it includes any plumbing or bedroom equivalents must be evaluated to determine whether the new structure encroaches on the setbacks for the existing system and to ensure that the designated 100% future expansion or replacement area is not impacted.

Site Evaluation Requirements When property owners want to develop their property, they begin the process with a Site Evaluation to determine soil type and depth and other site characteristics in order to determine whether or not it is feasible to utilize an onsite system for waste disposal. Site evaluations are required for approval of all parcel and subdivision maps and for construction of on-site wastewater systems. Accepted Site Evaluations will expire one year from the date of submittal. All properties where the septic designation in the Fresno County Permit Processing Program, (AMANDA), indicates “Engineered Design” shall require a Special Design System designed by a Qualified Professional as defined here in other than a Department Building Inspector.

Site Evaluation applications will be accepted when determined by the Department to be complete, and should including the following information if applicable:

A. Property Identification a. Property owner Name and Address b. Address of proposed/existing residences c. Assessor’s parcel number (APN) d. All Property Lines e. North Arrow f. Adjacent Streets g. Easements h. Narrative describing the basis of the Site Evaluation submittal, which shall include

reference to any other related County projects, if applicable. i. Applicant’s Name, Address and Signature j. Vicinity Map


B. Property Characteristics

a. Parcel size b. Vegetation c. Drainage(s), Lakes, ponds, or reservoirs & flood zone plain/zone info. d. Map should show the following for the subject parcel and within 150 feet past the

property line of the adjacent parcel(s.) 1) property boundaries 2) proposed and existing water well location(s) 3) home site 4) driveway(s) and parking area(s) 5) ancillary buildings 6) proposed percolation test locations if any 7) proposed test hole locations 8) proposed and existing dispersal fields 9) proposed and existing expansion area(s) 10) stream courses, shallow or outcropping bedrock 11) flood zone if any 12) and any other factors which may limit sewage dispersal.

Soil Profiles The sizing of the dispersal area in dispersal fields shall be predicated on the design flow for the proposed facility along with the application rate for the type of soil found in the proposed location for the original and replacement dispersal fields. See Table 4. Unless otherwise approved by the Department, a minimum of 2 Soil Profile Test Holes, [test hole(s)] will be required for each parcel, with at least one test hole excavated in the primary and one test hole excavated in the replacement dispersal areas. At the discretion of the Department, additional test holes may be needed to adequately characterize site conditions or fewer test holes may be allowed based on considerations such as space limitations on smaller parcels or uniformity of area soil characteristics. Test holes must be dug with a backhoe. Soil descriptions may be supplemented with soil boring information, but soil boring will not satisfy backhoe test hole requirements. Test holes must be excavated to the appropriate depth to verify that there is adequate vertical separation from groundwater and effective soil beneath the bottom of the dispersal system. Test holes must be dug in accordance with OSHA requirements, and must be 5 feet deeper than the proposed bottom of the dispersal system. If a seepage pit is proposed, it will require a test boring to the minimum depth of 10 feet deeper that the proposed design depth. The test boring shall be the same diameter as the proposed seepage pit. The excavated sidewall of the soil profile test hole should be picked away with a sharp instrument to expose the natural soil structure. The Qualified Professional shall identify each soil horizon from ground


surface to the bottom of the soil profile. Soil profile observations shall be documented for inclusion in the Site Evaluation or Site Plan and shall include a description of the following soil features:

a. Soil texture, color, structure, consistency, plasticity, and porosity for each soil horizon. b. Depth and type of limiting layer or condition; c. Depth of soil mottling, gleying or other evidence of periodic soil saturation; d. Depth of effective soil; and e. Other prominent soil features including but not limited to percentage of rock or coarse fragments,

root porosity, dampness, shrinkage cracks, gopher holes or depth and type of fill or imported soil in the profile.

Table 1: Design Soil Application Rates Calculated from Test Hole Soils Characterization

(Source: California State Water Resources Control Board Onsite Wastewater OWTS Policy, June 19,2012)

Soil Texture (per the USDA soil classification system)

Soil Structure Shape Grade

Maximum Soil

Application

Rate (gallons per day per

square foot)

Coarse Sand, Sand, Loamy Coarse

Sand, Loamy Sand Single grain Structureless 0.8

Fine Sand, Very Fine Sand, Loamy

Fine Sand, Loamy Very Fine Sand Single grain Structureless 0.4

Coarse Sandy Loam, Sandy Loam

Massive Structureless 0.2

Platy Weak 0.2

Moderate, Strong Special Design

Prismatic, Blocky,

Granular

Weak 0.4

Moderate, Strong 0.6

Fine Sandy Loam, very fine Sandy

Loam

Massive Structureless 0.2

Platy Weak, Moderate, Strong Special Design

Prismatic, Blocky,

Granular

Weak 0.2


Loam Massive Structureless 0.2


Prismatic, Blocky,

Granular

Weak 0.4


Silt Loam Massive Structureless Special Design



Prismatic, Blocky,

Granular

Weak 0.4


Sandy Clay Loam, Clay Loam, Silty

Clay Loam

Massive Structureless Special Design


Prismatic, Blocky,

Granular

Weak 0.2


Sandy Clay, Clay, or Silty Clay Massive Structureless Special Design


Prismatic, Blocky,

Granular

Weak Special Design


Percolation Testing If there is any question about the soil texture or structure, grade or proposed use of seepage pits, the proposed site shall be subject to percolation tests. Soil percolation testing shall be performed under the responsible charge of a Qualified Professional as allowed by their license and registration. Percolation testing is performed to provide information required to determine the potential wastewater absorption rate of soil in the dispersal system areas including the expansion or reserve areas. Percolation testing does not replace the need or requirement for a soil profile study, soil textural determination and determination of high seasonal groundwater levels. Percolation test hole preparation requirements for dispersal field are as follows:

1. Unless otherwise indicated by the Department, there shall be a minimum of three (3) percolation test holes when the disposal area and the expansion or reserve/replacement area are in the same proximity as determined by the Department; six (6) percolation test holes may be required when separate areas are chosen for primary and replacement systems. Additional percolation test holes may be required by the Department to completely identify a suitable area for a dispersal system.

2. Percolation test holes shall be six (6) inches in diameter. 3. Unless otherwise approved by the Department, the percolation test hole bottom depth shall be

deeper than the proposed dispersal system bottom depth and within the most restrictive strata of useable soil beneath the dispersal field.

4. The percolation test hole sidewall in the test section should be roughened to remove any smearing or compaction caused by the hole excavation process. All loose soil shall be removed, and two (2) inches of pea gravel or other material approved by the Department shall be placed in the bottom of the hole.


Table 2: Application Rates as Determined from Stabilized Percolation Rate

(Source: California State Water Resources Control Board Onsite Wastewater OWTS Policy, June 19,2012)

Percolation Application Percolation Application Percolation Application

Rate Rate Rate Rate Rate Rate

(mins/ inch) (Gallons/day/ sq.ft) (mins/ inch) (Gallons/day/ sqft) (mins/ inch) (Gallons/day/ sqft)

<1 Requires Local Management Program

1 1.2 31 0.522 61 0.197

2 1.2 32 0.511 62 0.194

3 1.2 33 0.5 63 0.19

4 1.2 34 0.489 64 0.187

5 1.2 35 0.478 65 0.184

6 0.8 36 0.467 66 0.18

7 0.8 37 0.456 67 0.177

8 0.8 38 0.445 68 0.174

9 0.8 39 0.434 69 0.17

10 0.8 40 0.422 70 0.167

11 0.786 41 0.411 71 0.164

12 0.771 42 0.4 72 0.16

13 0.757 43 0.389 73 0.157

14 0.743 44 0.378 74 0.154

15 0.729 45 0.367 75 0.15

16 0.714 46 0.356 76 0.147

17 0.7 47 0.345 77 0.144

18 0.686 48 0.334 78 0.14

19 0.671 49 0.323 79 0.137

20 0.657 50 0.311 80 0.133

21 0.643 51 0.3 81 0.13

22 0.629 52 0.289 82 0.127

23 0.614 53 0.278 83 0.123

24 0.6 54 0.267 84 0.12

25 0.589 55 0.256 85 0.117

26 0.578 56 0.245 86 0.113

27 0.567 57 0.234 87 0.11

28 0.556 58 0.223 88 0.107

29 0.545 59 0.212 89 0.103

30 0.533 60 0.2 90 0.1

>90-120 0.1


Soil application rates will be determined using Table 2 and/or the following equation to convert the average percolation rate (or infiltration rate) into the application rate [gallons-per-day (gpd)-persq.ft.]: where Q = application rate, t = average percolation rate.

𝑸 =5

√t

EXAMPLE: t = 75 mpi, therefore Q = 0.58 gpd/sq.ft.

The average of all percolation tests in the leaching area shall not exceed two hundred (200) minutes per inch (mi./inch). No single percolation test shall exceed two hundred-forty (240) mi./inch. Wastewater Design Flow Requirements The Qualified Professional is responsible for ensuring that the wastewater flow rate used for the design of Onsite Wastewater Systems is developed based on full consideration of projected activities, occupancy and types of facilities.

Table 3: Estimate of Wastewater Design Flow Rates Non-Residential

Type of Business or Facility Minimum Flow (Gallons/ Day)

Bathhouses and swimming pools 10 (per person)

Barbershop/salon 100 (per chair)

Camps (4 persons per campsite, where applicable)

-with central comfort stations

-with flush toilets, no showers

-construction camps (semi-permanent)

-day camps (no meals served)

-resort camps (night and day) with limited plumbing

35 (per person)

25 (per person)

50 (per person)

15 (per person)

50 (per person)

Churches

-with kitchen

-without kitchen

15 (per seat)

5 (per seat)

Country clubs

-per resident member

-add per nonresident member present

-add per employee

100

25

15 (per 8 hour shift)

Department store with public bathrooms 400

Dentist office

-per wet chair

-add per non-wet chair

200 50

Factories

-with shower facilities, no food service or industrial wastes

-without shower facilities, no food, service or industrial wastes

35 (per person, per shift) 15 (per person, per shift)

Hospitals 250 (per bed space)

Hotels or motels

-with private baths

-without private baths

100 (per room)

80 (per room)


Institutions other than hospitals 125 (per bed)

Laundries, self-service washing machines 500 (per machine)

Limited agricultural building 100 (per building)

Mobile home parks 250 (per space)

Parks, public picnic areas -with toilet wastes only -with bathhouses, showers and flush toilets

5 (per person) 10 (per person)

Restaurants -with multi-use utensils -with single service utensils -with bars and/or cocktail lounges

50 (per seat) 25 (per seat) 50 (per seat)

Residential Structures -Second dwelling, condominium, multi- family (duplex, triplex, etc.) -Guesthouse/Poolhouse (no kitchen)

150 per Bedroom

Retail stores -for customer -add for each employee

-Use comparable flows from similar businesses -15 (per 8-hr shift)

Shopping center 2 (per parking space)

Schools -boarding -day (without gyms, cafeterias or showers) -day (with gyms, cafeterias and showers) -day (with cafeteria, no gym or showers)

100 (per person) 15 (per person) 25 (per person) 20 (per person)

Service stations 500 for 1st pump set, 300 for each additional

Theaters -movie -drive-in

5 (per seat) 20 (per car space)

Recreational vehicle parks -without individual water and sewer hookups -with individual water sewer hookups

50 (per space) 100 (per space)

Table 4: Design Criteria of Five Typical Soils

TYPE OF SOIL

REQUIRED SQUARE FEET OF LEACHING AREA PER 100

GALLONS

MAXIMUM ABSORPTION CAPACITY IN GALLONS PER SQUARE FEET OF

LEAHCING AREA FOR A 24 HOUR PERIOD

Course sand or gravel 20 5.0

Fine sand 25 4.0

Sandy loam or sandy clay 40 2.5

Clay with extensive sand or gravel 90 1.1

Clay with some sand or gravel 120 0.8


Site Plan Requirements An important step in the Site Evaluation process is the preparation of a site plan to identify physical features of the parcel and adjacent parcels that may impact system siting and performance, as well as proposed land use projects. The site plan will be used as the base map for Onsite Wastewater System evaluation and design. Site plans for Special Design systems shall be prepared by a Qualified Professional as allowed by their registration and license. The Department requires that the following items be provided with a site plan before a permit will be issued for the construction or repair of a Special Design private sewage dispersal system:

1. Plot plan drawn to scale, completely dimensioned, of the parcel and extending at least 150 feet past the property line, showing direction and approximate slope of surface, location of present or proposed retaining walls, drainage channels, water supply lines or wells, paved areas and structures on the plot, number of bedrooms or plumbing fixtures in each structure, and location of the private Special Design sewage dispersal system with relation to lot lines and structures.

2. Recommended method of sewage treatment. 3. Estimated sewage flow

a. Designs for commercial Special Design system applications shall provide calculations based upon both fixture units and proposed occupancy, for which the final design shall utilize the more conservative calculation.

4. Average soil permeability-percolation test hole results. 5. Applicable soil application rate [gallons per day per square feet (gpd/sq.ft.)] based on soil group

in Table 1 or percolation rates per Table 2. 6. Minimum capacity of septic tank. 7. With or without garbage grinder. 8. Dispersal Trench /Seepage Pit construction.

a. Width b. Total depth c. Depth of leach line or inlet to seepage pit d. Spacing between trenches or pits e. Venting system (if required) f. Total dispersal area requirements g. Dispersal area per linear feet allowed or dispersal area provided per pit h. Required total length of dispersal trench or number of pits i. Area of house and number of bedrooms

9. Details of construction, along with a full description of the complete installation including quality, kind, and grade of materials, equipment, construction, workmanship, and methods of assembly and installation.

10. A log of soil formations and groundwater levels as determined by test holes prepared by the qualified professional that are dug in close proximity to a proposed dispersal field or seepage pit, together with a statement of water dispersal characteristics of the soil at the proposed site, and/or as determined by approved percolation tests.

11. All drawings and specifications shall be signed and stamped as appropriate by a Qualified Professional. Submittals will be valid for one-year from the date of submittal to the County.


Setback Distances for OWTSs

Table 5 Setback Distances for OWTSs

Minimum Setback Required From Building Sewer

Septic Tank

Dispersal Field Seepage Pit

Non-Public Water Supply Well and Springs 50 feet 1 100 feet 100 feet 1 150 feet 1

Public Water Supply Well Dispersal System Depth

Less than 10 feet 50 feet 1 100 feet 150 feet 1 150 feet 1

Greater than 10 feet and Less than 20 feet 50 feet 1 100 feet 200 feet 1 200 feet 1

Greater than 10 feet and Less than 20 feet 50 feet 1 100 feet No less than 200 feet 1,12

No less than 200 feet 1,12

Distance < 1200 feet 2 - 100 feet 400 feet 400 feet

Distance 1200- 2500 feet 2 - 100 feet 200 feet 200 feet

Building or Structures 2 feet 5 feet 8 feet 8 feet

Property line adjoining private property 3 Clear 11 50 feet 50 feet 75 feet

Streams and other flowing bodies of water 50 feet 100 feet 4 100 feet 4 150 feet 4

Drainage Course/Seasonal Streams/ Unlined Canal 25 feet 50 feet 50 feet 50 feet

Lakes, ponds, stormwater/recharge basins, and other surface water bodies 50 feet 100 feet 200 feet 200 feet

Residential on-site stormwater basins 15 15 15 15

Trees - 10 feet - 10 feet

Seepage Pits 5 - 5 feet 5 feet 12 feet

Dispersal field 5 - 5 feet 4 feet 6 5 feet

On-site domestic water line 1-foot 10 5 feet 5 feet 5 feet

Pressure public water main 10 feet 10 feet 10 feet 10 feet

Distribution Box - - 5 feet 5 feet

Cuts or steep embankments (from top of cut) - 10 feet 4xh 7, 8 4xh 7, 8

Steep slopes (from break of slope) - 10 feet 4xh 7, 8 4xh 7, 8

Road easement, pavement, or driveway - 5 feet 5 feet 5 feet

Unstable Land Mass 9 - - 100 feet 100 feet


1 Drainage piping shall clear domestic water supply wells by not less than 50 feet. This distance shall be permitted to be reduced to not less than 25 feet where the drainage piping is constructed of materials approved for use within a building. 2 Where the effluent dispersal system is within 1,200 feet from a public water systems' surface water intake point, within the catchment of the drainage, and located such that it may impact water quality at the intake point such as upstream of the intake point for flowing water bodies, the dispersal system shall be no less than 400 feet from the high water mark of the reservoir, lake of flowing water body. Where the effluent dispersal system is located more than 1,200 but less than 2,500 feet from a public water systems' surface water intake point, the dispersal system shall be no less than 200 feet from the high water mark of the reservoir, lake, or flowing water body. 3 Reduction of required setback may be obtained through variance request, should the applicant be able to demonstrate an inability to meet required setback, while not infringing upon the development potential of the adjacent property. 4 These minimum clear horizontal distances shall also apply between dispersal fields, seepage pits, and the mean high-tide line. 5 Where dispersal fields, seepage pits, or both are installed on sloping ground, the minimum horizontal distance between any part of the leaching system and ground surface shall be 15 feet. 6 Plus 2 feet for each additional 1 foot of depth in excess of 1 foot below the bottom of the drain line. 7 h equals the height of the cut or embankment, in feet. The required setback distance shall not be less than 25 feet nor more than 100 feet. 8 Steep slope is considered to be land with a slope of > 30% and distinctly steeper (at least 20% steeper) than the slope of the adjacent tank or dispersal field area. 9 Unstable land mass or any areas subject to earth slides identified by a registered engineer or registered geologist ; other setback distance are allowed, if recommended by a geotechnical report prepared by a qualified professional. 10 See Section 720.0 of the California Plumbing Code. 11 See also Section 313.3 of the California Plumbing Code 12 Where the dispersal system is greater than 20' in depth, and less than 600' from public water supply well, then the setback must be greater than the distance for two-year travel time of microbiological contaminants, as determined by qualified professional. In no case shall the setback be less than 200'

Geotechnical Evaluations A Slope Stability Report approved by a registered engineering geologist or civil engineer is required whenever natural ground slopes in dispersal areas are greater than 30%.

System Types

Standard OWTS. A standard OWTS consists of a septic tank for primary treatment of wastewater followed by a system of gravity fed trenches for subsurface dispersal of wastewater into the soil (gravity trench dispersal system). A standard OWTS utilizes gravity flow to convey wastewater from the septic tank to the gravity trench dispersal system. A pump tank may be utilized to enable the installation of a gravity trench dispersal system located up-slope of the structure or building to be served.

Tank Requirements As of January 1, 1993, the Department will only accept septic tank products which are listed by International Association of Plumbing and Mechanical Officials (IAPMO) or by other recognized listing agencies, and comply with state and local building codes, including the California Plumbing Code.

All new or replacement tanks shall meet the standards of the local Building Official and their installation shall be according to manufacturer’s recommendations.

As defined in the LAMP, all new or replacement tanks shall be a minimum of 1,500 gallons in order to maximize retention and treatment capacity.


All joints between the septic tank and its components shall be watertight and constructed of listed solid, durable materials to prevent infiltration (or inflow) of groundwater and surface water, exfiltration (or outflow) of wastewater, or excessive corrosion or decay.

Septic tanks shall have weather-tight manholes (risers) accessible by extending the manhole openings to grade if installed under concrete or blacktop paving, or within 6-inches of finished grade if under soil cover in a manner acceptable to the Department. Access openings at grade or above shall be locked or secured to prevent unauthorized access.

Subsurface Dispersal

The types of subsurface dispersal systems approved for use in the County include: a. Gravity trench dispersal systems;

b. Seepage pits shall be used only to service a single-family residence and only when the site is not acceptable for installation of a standard or other special system. c. All other dispersal systems designed by a Qualified Professional and approved by the Department.

General subsurface disposal system requirements include the following:

Table 6 MINIMUM

MAXIMUM

Number of drain lines per field 1 -

Length of each line - 100 feet

Bottom width of trench 18 inches 36 inches

Spacing of lines, center-to-center 6 feet -

Depth of earth cover of lines (preferred -18 inches) 12 inches 9 feet

Grade of lines Level 3 inches per 100 feet

Filter material under drain lines 12 -

Filter material over drain lines 2 inches -

Square feet of trench bottom 150 Square feet

Distribution Boxes Where two or more drain lines are installed, an approved distribution box of sufficient size to receive lateral lines shall be installed at the head of each dispersal field. The inverts of outlets shall be level, and the invert of the inlet shall be not less than 1 inch (25.4 mm) above the outlets. Distribution boxes shall be designed to ensure equal flow and shall be installed on level natural or compacted soil. Connections between a septic tank and a distribution box shall be laid with approved pipe with watertight joints on natural ground or compacted fill. Laterals Laterals from a distribution box to the dispersal field shall be approved pipe with watertight joints. Multiple dispersal field laterals, where practicable, shall be of uniform length.


Dispersal Fields Where dispersal fields are installed, not less than 150 square feet of trench bottom shall be provided for each system exclusive of any hardpan, rock, clay, or other impervious formations. Trench width is limited to a maximum of 36 inches. The first foot of both sidewalls underneath the pipe is not allowed to be used in calculating the square footage of the dispersal area. The sidewall area allowed in the calculation is not to exceed 36 inches when computing dispersal area per lineal foot of trench unless approved within a special design system. Where necessary on sloping ground to prevent excessive line slope, leach lines shall be stepped to utilize the maximum capacity of each line before the effluent passes to the next lower line. Grease Interceptors

Where liquid wastes contain excessive amounts of grease or lint that affect the operation of a private sewage dispersal system, an interceptor for such grease or lint shall be installed.

Installation of such interceptors shall comply with applicable setback requirements. Seepage Pits Seepage pits shall be used in areas of the County where subsoils such as clay, clay pan, fragipan, or hard pan prohibit the use of a typical leach trench disposal system. Seepage pits shall be used only to service a single-family residence and only when the site is not approvable for installation of a standard or other special system. Construction Materials Tanks: All tanks and interceptors are to be watertight and constructed of durable, corrosion resistant material and shall conform to latest version of the International Association of Plumbing and Mechanical Officials (IAPMO) and National Sanitation Foundation (NSF) standards and comply with state and local building standards codes, including the California Plumbing Code. Wooden septic tanks and components, including tops and baffles, are prohibited. Distribution Lines: Distribution lines shall be constructed and listed perforated high- density polyethylene pipe, perforated ABS pipe, perforated PVC pipe, or other approved materials, provided that approved openings are available for distribution of the effluent into the trench area. Seepage Pits: The seepage pit shall be filled up to the concrete collar with leach rock or cobbles that are a minimum of three quarters (3/4”) inches (19.1 mm) and two and one half (2.5”) inches (64 mm) in diameter in any dimension or with other filter material approved by the Department. The cobbles or filter material shall be washed clean to be free of debris and dirt. System Destructions A cesspool, a septic tank, or a seepage pit that has been abandoned or has been discontinued otherwise from further use, or to which no waste or soil pipe from a plumbing fixture is connected, shall have the sewage removed therefrom and be completely filled with the earth, sand, gravel, concrete, or other approved material.


Variances

Variances for new installations and repairs will be in substantial conformance to the OWTS Policy and LAMP, to the greatest extent practicable. The Department will review any request for a variance and may deny it, though, the Department shall be permitted to grant exceptions to the provisions of the LAMP for repairs of existing OWTS and for permitted structures that have been destroyed due to fire or natural disaster and that cannot be reconstructed in compliance with these provisions provided that such exceptions are the minimum necessary. Variances that require a nitrogen loading analysis will depend on the concurrence and input of the RWQCB in order to be approved by the Department. The analysis will be referred to the State Water Resources Control Board at http://www.waterboards.ca.gov.

Variances cannot be authorized for:

1) Cesspools of any kind or size. 2) OWTS receiving a projected flow over 3,500 gallons per day. 3) OWTS that utilize any form of effluent dispersal that discharges on or above the post

installation ground surface such as sprinklers, exposed drip lines, free-surface wetlands, or a pond.

4) Slopes greater than 30 percent without a slope stability report approved by a registered engineering geologist or civil engineer.

5) Decreased leaching area for IAPMO certified dispersal systems using a multiplier less than 1.0.

6) OWTS utilizing supplemental treatment without requirements for periodic monitoring or inspections.

7) OWTS dedicated to receiving significant amounts of wastes dumped from RV holding tanks. 8) Separation of the bottom of dispersal system to groundwater less than five (5) feet, except

for seepage pits, which shall not be less than 10 feet. 9) Installation of new or replacement OWTS where public sewer is available. The public sewer

may be considered as not available when such public sewer or any building or exterior drainage facility connected thereto is located more than 200 feet from any proposed building or exterior drainage facility on any lot or premises that abuts and is served by such public sewer. This provision does not apply to replacement OWTS where the connection fees and construction cost are greater than twice the total cost of the replacement OWTS and the local agency determines that the discharge from the OWTS will not affect groundwater or surface water to a degree that makes it unfit for drinking or other uses.

Existing OWTS and Bedroom Additions Existing OWTS that are properly functioning are considered Tier 0. In order to provide substantial compliance with this LAMP, to the greatest extent practical without causing excessive hardship to the property owner, the addition of one bedroom without changes to the existing OWTS will be permitted. The addition of two bedrooms will require leaching to be added in compliance with the LAMP. The addition of three or more bedrooms will require strict compliance to the LAMP.


Review and Inspection Requirements Special Design OWTS Approval Special Design Onsite Wastewater System plans shall be drawn to scale with details sufficient to allow Department staff to review for compliance with the requirements of the Ordinance and this Manual. Supervising Building Inspectors will review Special Design OWTS plans for approval. . Final System Installation Approval Department inspections of System installation and abandonment are required to ensure conformance with the standards in County of Fresno LAMP. The System must be ready for the type of inspection requested or specified in each step in the installation process. No portion of the System shall be covered without prior inspection and approval by the Department. A Final inspection is required to verify that all construction was completed in conformance with the approved plans and specifications. Systems designed by a Qualified Professional shall be verified and plotted by the Department, inspected by the Qualified Professional and a letter of acceptance shall be provided to the Department from the Qualified Professional in order to gain Department approval.

Complaints and Investigations A complaint regarding an Onsite Wastewater System may be filed with the Department Code enforcement staff by calling 559-600-4560, or contacting via Internet http://www.co.fresno.ca.us/departments/public-works-planning/divisions-of-public-works-and-planning/development-services-division/code-enforcement. Upon receipt of a complaint, Department Code Enforcement staff will conduct a complaint assessment and/or investigation. The actions that the Department may take include the following:

a. The Department Code Enforcement will contact the complainant to collect information about the alleged violation.

b. After verification of the complaint, appropriate measures will be implemented to abate the violation.

c. The Department, Code Enforcement Unit will enforce Corrective Actions through Chapter 1.13 Administrative Fines Ordinance.

Reporting Requirements Annual Report An annual report will be submitted to the RWQCB by February 1 of each year that includes the following information:

(1) Number and location of complaints, and means of resolution. (2) Application and registrations of septic tank cleaners. (3) Number, location, description and risk tier of all OWTS permits. (4) Number, location, description and risk tier of all variances. (5) Water Quality Monitoring data.

http://www.co.fresno.ca.us/departments/public-works-planning/divisions-of-public-works-and-planning/development-services-division/code-enforcement

http://www.co.fresno.ca.us/departments/public-works-planning/divisions-of-public-works-and-planning/development-services-division/code-enforcement


Permanent Records The Department will retain all permanent records and will make them available within ten (10) working days upon written request by the RWQCB. All Department permitting actions are also available to the public upon request. The Department will maintain records associated with any variance granted.

Fifth Year Report Every fifth-year, Fresno County will submit an evaluation of the monitoring program and an assessment of whether water quality is being impacted by OWTS and identify any necessary changes to the LAMP in order to address impacts from OWTS. Water Quality Data Fresno County will maintain a water quality assessment program that consists of obtaining water quality data from the following sources:

(1) Regulated small water systems in Fresno County (SWS) (2) Wells within Fresno County that are monitored as part of the Statewide Groundwater Ambient Monitoring and Assessment (GAMA) program (3) Domestic wells sampled at the request of property owner at the time of well installation. Assessment Program Fresno County will maintain a water quality assessment program to determine the general operation status of OWTS and to evaluate the impact of OWTS discharges, and assess the extent to which groundwater and local surface water quality may be adversely impacted. The focus of the assessment should be areas identified with shallow soils, high domestic well usage, fractured rock, poorly drained soils, and surface waters vulnerable to pollution.

The assessment program will include monitoring and analysis of water quality data, review of complaints, variances, failures, and any information resulting from inspections. The assessment may use existing water quality data from other monitoring programs and/or establish the terms, conditions, and timing for monitoring done by the local agency. At a minimum, this assessment will include monitoring data for nitrates and pathogens, and may include data from other constituents which are needed to adequately characterize the impacts of OWTS on water quality. Other monitoring programs for which data may be used include but are not limited to any of the following:

(1) Random well samples from a domestic well sampling program. (2) Review of public system sampling reports done by the local agency or another municipality responsible for the public system. (3) Water quality testing reports done at the time of new well development if those are reported. (4) Receiving water sampling performed as a part of a NPDES permit. (5) Groundwater sampling performed as part of Waste Discharge Requirements. (6) Groundwater data collected as part of the Groundwater Ambient Monitoring and Assessment Program and available in the Geotracker Database.

ONSITE WASTEWATER TREATMENT SYSTEMS GUIDANCE MANUAL

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