DESIGN STANDARDS FOR THE SITE EVALUATION AND DESIGN OF SEWAGE DISPOSAL SYSTEMS
Section 1 - General Provisions
A. Site Evaluation
B. Site Evaluation Process
E. Enforcement Actions
Section 2 - Design Procedures
A. General Requirements
B. Standard Systems
C. Special Design Systems
D. Capping Fill Systems
E. Pressurized Distribution Systems
F. Pump Systems
G. Steep Slope Systems
H. Intermittent and Re-circulating Sand Filter Systems
I. Mound Systems
J. Package Plant Systems
K. Gray water Systems
L. Experimental Systems
M. Large System Requirements
N. Aerobic System Requirements
O. Holding Tanks and Cesspools
Section 3 - Materials and Construction
A. Septic Tank Requirements
B. Serial Distribution Materials and Construction
C. Diversion Valve Materials and Construction
D. Effluent Pump, Control, and Alarm Materials and Construction
E. Pipe Materials and Construction
F. Curtain Drain Design, Materials, and Construction
G. Leach Line Construction
H. Commercial or Industrial Special Liquid Waste Disposal
Section 4 - Appendices
DESIGN STANDARDS FOR THE SITE EVALUATION & DESIGN OF SEWAGE DISPOSAL SYSTEMS
Section 1 - General Provisions
A. SITE EVALUATION
A site evaluation, a site approval report and a sewage disposal system permit are needed to install or change a system. This applies whether you are an owner, contractor, company, or public agency. A permit will only be issued to an owner or the owner's authorized representative.
A site evaluation is the procedure where your consultant and the Environmental Health, staff meet at the property and evaluate the site's ability to dispose of sewage. This is where the initial soils' evaluation is done (i.e., "soil observation pit"). Once the site evaluation is finished, your consultant will prepare and submit to Environmental Health a site evaluation report. The Division will then produce a site approval report, which approves or disapproves a location on the parcel for a sewage disposal system permit application.
The site evaluation approval is separate from the sewage disposal system permit. The sewage disposal system permit application is the actual process for obtaining the permit to work on your system, and generally is in conjunction with your building permit.
B. SITE EVALUATION PROCESS
1. Review Division Records: A site approval report is not required where soils testing was conducted prior to the adoption of this Chapter and the Department finds that the site and prior test results are acceptable. Division soil reports on file may be reviewed.
2. Obtain A Consultant: See section 15.32010a. It will be necessary to obtain a consultant to make the site evaluation. The consultant will work with Environmental Health and will assist the property owner in locating the appropriate sewage disposal site on the parcel. The consultant is the person that performs the percolation tests, examines the soil observation pit(s), and prepares the site evaluation report.
Make an Application and Pay, The Required Fee:
a) Obtain a permit and make an appointment for a site evaluation with the Division.
b) The application form for this service must be filled out completely by the owner or the Owner's authorized representative.
c) It is important that sufficient information be provided with the application. This must include:
1) An accurate location map.
2) A legible copy of the Assessor's map.
3) Additional information will include: A copy of the survey map (if applicable), location of wells, streams, ponds, drainage ways, proposed house site, existing buildings, rock outcrops, easements, proposed driveways, and cuts and fills. See diagram #9.
4. Conduct A Site Evaluation:
a) The consultant, the backhoe operator, and the Division representative will meet at the property.
b) Soil observation pit(s) will be excavated in the area proposed for the sewage disposal system and the replacement area. Additional soil observation pits may be required to locate a suitable area for the sewage disposal system.
c) Along with the soil observation pits, the overall site will be evaluated by the Division and the consultant for other considerations such as slope, leaking irrigation ditches, setbacks, road cuts, etc. The Division will complete a field report for each site evaluated. The field report will contain information that defines all areas tested, and comments on, the ability to dispose of sewage. All soil observation pits must be backfilled upon completion of the evaluation for the purpose of safety and erosion control. There are specific State laws which also regulate this. For greatest safety, the soil observation pits should be back filled upon completion of the evaluation.
5. Wet Weather Testing: The Division may require that a parcel be tested during the wet weather test season before a system site is approved, based on revealing conditions seen in the soil observation pit. This requirement may also be set based on historical soils information available for an area.
6. Percolation Test: Percolation tests are required before a site evaluation report can be completed. Percolation tests must be done according to the requirements specified in the Design Procedures Section I b of this resolution.
7. Site Approval Report: The purpose of the site evaluation is to determine whether or not a parcel can accommodate an onsite sewage disposal system.
a) Regardless of the outcome of the site evaluation, the consultant must provide the Division with a site evaluation report, including a scaled (I "=50' minimum) site plan identifying the location of all soils testing performed. For sites where a sewage disposal area is identified, the proposed system area must be shown. The consultant must submit the site evaluation report within 60 days of completion of the site evaluation.
b) A site evaluation field report must be prepared by the consultant and approved by Environmental Health before a sewage disposal system permit application can be accepted. (Exception: A site approval report is not required where soil testing was conducted prior to the adoption of these regulations and the Division finds that the site and prior test results are acceptable.) The site approval report is not a permit to install a system.
c) The site evaluation field report will specify the type(s) of system(s), if any, that can be approved for a specific site. It will also note any specific limitations or conditions that may be part of the approval of a system.
d) A site evaluation field report is transferable and runs with the land.
e) Changes in laws governing sewage disposal systems may require a modification to the site evaluation field report.
f) The site evaluation field report and approval for a sewage disposal area are based upon property conditions at the date of the report. Changes made to the property may render that area unacceptable. Examples of types of changes include: grading, cuts and fills, new buildings, wells, ponds, etc. The property owners must take care not to encumber or alter the approved area in a manner that affects the future system.
1. Sewage Disposal Report - Sewage Disposal Report shall include the site/plot plan (copy of grading plan when required by the County), percolation report, design calculations, and four (4) legible copies of the sewage disposal system design. The design shall be on a scale not exceeding one (1) inch to fifty (50) feet, no larger than 8 2" x 14" or smaller than 8 2" x 11 ", showing the following (use more than one sheet if necessary):
- (a) A scale drawing of the parcel configuration
- (b) Frontage road and easements
- (c) Distance from house to property lines or road easements
- (d) Distance from house to septic tank
- (e) Distance from septic tank to leach lines
- (f) Exact length, width, and depth of all leach lines
- (g) Distance from leach lines to property lines and road easements
- (h) The exact area to be used for 100% / 300% replacement
- (i) The scale used for the plot plan
- 0) North arrow
- (k) The percent of slope of the ground in the sewage disposal area And 100% / 300% replacement area or topographic map with minimum five (5) foot contour intervals.
- (l) The location of all wells on the parcel or on adjacent parcels. The location of rivers, streams (permanent or ephemeral), lakes, ponds (permanent or ephemeral), water supply, ditches, springs, and wet areas in proximity of the sewage disposal system area. Refer to Table I for specific setbacks.
- (m) Water pipelines, rock outcrops, hardpan, lava caps, cuts, fills, slopes over 30%, retaining walls, and pools.
- (n) Cross-section of the trench
- (o) Distribution of effluent
- (p) Details of construction necessary to assure compliance with these requirements.
- (q) Any special considerations required in the installation of the proposed system. If any of the above data is not provided, approval will be withheld pending submission of the necessary data.
- (r) Location of percolation test holes and test pits.
- (s) Accurate driving directions to the parcel or vicinity map.
- (t) Proposed cuts and /or fills on the property.
2. Test Data Report - Test data report shall include the following:
Current assessors parcel number of property.
- (b) The person who performed the test, his address, zip code, phone number, title, registration number, and signature.
- (c) Weather conditions, time, and temperature at time of test.
- (d) The number of bedrooms in the existing or proposed structure(s), or number of fixture units if other than single family dwelling.
- (e) The location of test holes on a plot map. Include the contours or direction of slope of the land; location of lakes or streams, outcrops, existing or proposed structures or wells; location and approximate height of road cuts, if any, and location and type of surface vegetation.
- (f) Depth and soil profiles of each hole.
- (g) All percolation rate measurements taken and stabilized percolation rate. Report the percolation measurements and rates as minutes per inch (the minutes required for the water to drop one (1) inch in a six (6) inch hole).
- (h) Percolation rates in excess of sixty (60) minutes per inch for standard leach lines and thirty (30) minutes per inch for non-standard leach lines shall require "Special Design".
- (i) Describe soil profile in the leach field area - including roots, clay lenses, rock type and amount, texture, moisture, depth to groundwater, and other unusual aspects.
- (j) Soil description as per the soil survey of El Dorado County area, USDA.
1. General Inspection Requirements
- (a) Inspections will only be performed on sewage disposal systems and site evaluation test pits done under a valid permit. The permit number must be provided when an inspection is requested.
- (b) Minor Revisions: A change in tank location, a change in distribution box location or line location adjustments for contour or obstructions within the approved sewage disposal area shall be considered minor revisions. Minor revisions shall be drawn clearly and to-scale on the original approved plot plan and signed by the designer as an "as-built"@ system.
- (c) Major Revisions: Changes in depth, width or location of the sewage disposal system shall be considered major revisions. A revised plot plan shall be prepared, showing these major revisions, and shall be re-approved by the Department prior to any inspections.
- (d) Systems overseen by a Public Entity will not be finalized until a letter of completion and an "As Built 'plot plan is received from the Public Entity.
- (e) Testing:
- Septic tanks or other primary components may be required to be filled with water to the flow line prior to requesting inspection. All seams or joints shall be left exposed (except the bottom) and the tank shall remain watertight.
- A flow test may be required to be performed through the system to the point of effluent disposal. All lines and components shall be watertight and distribution shall be according to the approved plan.
- (f) The system must be ready for the type of inspection requested. If extra inspections are needed, an additional inspection fee will be charged.
2. Site Evaluation Inspections
(a) Site evaluation test pits will be inspected by the Department and the consultant. The test pit will be dug to 5 feet below the proposed designed depth.
3. Open Trench Inspections
(a) Open trench inspections shall be performed by the Department on all standard systems. Open trench inspections on all other systems shall be performed by the designer.
(b) At the time of the open trench inspection, all the following shall be completed:
All excavations necessary for the system at designed depth, width, and length.
All smeared or compacted surfaces shall be removed.
Bottom of the trenches shall be level.
Minimum setbacks shall be in accordance with the approved plat plan.
4. Final Inspections
(a) All systems shall receive a final inspection by the Department. Some systems may have special requirements for the final inspection. Refer to the table of contents to find the appropriate section in this resolution for specific requirements.
(b) A final inspection on a special design disposal system will only be performed when there is an "as-built" plot plan on site signed on the Environmental Health stamp by the designer and the installer. The plot plan must indicate all revisions.
(c) At the time of final inspection by the Department, all the following shall be completed:
- The trenches filled with rock to the specified level with the filter material in place or the gravel-less chambers installed.
- Approved distribution boxes, with covers, installed level on undisturbed soil and at the proper elevation.
- All pipe, other than in trenches, must be installed on grade (1/8 in./ft. minimum) and grouted to tank or distribution boxes.
- All pipe in trenches installed level (maximum drop of 3 " in 100 ft.) in the full length of trenches with ends capped. Sealing around pipe is also to be completed at the distribution boxes.
- The septic tank set level in place on undisturbed soil and a layer of approved bedding material may be used.
- All trenches must be uncovered to the filter material and visible for inspection - do not backfill.
1. Enforcement Actions When there is a violation, the Department may exercise enforcement action in any or all of the following manner(s).
(a) The Department may issue a notice of inspection, correction notice, suspend a permit, and/or record a Notice of Non-compliance with the County Recorders Office;
(b) The violator(s) may be issued a citation for violations pursuant to El Dorado County Code Title 1: General Provisions, Chapter 1. 16;
(c) The Department may instigate criminal proceedings by referring the matter to the El Dorado County District Attorney.
2. Enforcement Action Procedures
(a) Notice of Inspection: The Department may directs the cessation or correction of a violation or public health hazard. The notice will direct immediate measures required to eliminate a potential or actual public health hazard or a public nuisance. Failure to comply with the requirements of a Notice of Inspection is a violation of this resolution and is subject to any or all of the enforcement actions prescribed in this Section.
(b) Correction Notice: The Department may issue a Correction Notice upon a person responsible for working on a system or operating a system where that work or operation is in violation of this ordinance and/or conditions of the sewage disposal system permit or operating permit. The Correction Notice will state the violation(s). Failure to correct the stated violation(s) is a violation of this resolution and is subject to any or all of the enforcement actions prescribed in this Section.
(c) Stop Work Order: The Department may issue a Stop Work Order for work that is in violation of this ordinance, the sewage disposal system permit, or is occurring in an unsafe and dangerous manner. The Stop Work Order will be issued to the person responsible for the work, and will specify the reason for the Stop Work Order. It may also direct corrective measures necessary to abate the violation. Work may only recommence upon written release by the Department. Failure to comply with the requirements of a Stop Work Order is a violation of this resolution and is subject to any or all of the enforcement actions prescribed in this Section.
(d) Permit Suspension:
(1) When the construction or operation of a system is in violation of this resolution or conditions of the permit, or where a person has misrepresented any material fact in the application for a permit, the Department may suspend the pen-nit.
(2) The Department will provide the owner a written notice of intent to suspend a permit. The owner will be given the opportunity to request a hearing with the Department. A written request for a hearing must be received by the Department within ten (10) working days of the Division's written notice. A failure to request the hearing within the ten (10) working days is deemed a waiver of the right to a hearing.
(3) The Department will schedule a hearing within ten (10) working days from the receipt of a written request for a hearing. The Director of Environmental Management or designee shall conduct the hearing. The decision resulting from the hearing may be appealed in accordance with El Dorado County Code Chapter 15, Section 15.32.044.
(4) No work, use, or operation may continue on a system where the permit has been suspended. Work or operation on a system with a suspended permit may recommence upon reinstatement of the permit in writing by the Department. Before the permit will be reinstated, any hourly fees pending must be paid in fall.
Section 2 - Design Procedures
A. GENERAL REQUIREMENTS
1. Soil and Groundwater Determination (Test Pits)
(a) Soil depth must be four (4) feet below the bottom of the trench.
(b) Groundwater must be a minimum of four (4) feet below the bottom of the trench. Unless mitigated by an approved special design system (as per section C-L).
(c) When in an area of potential groundwater, or shallow soils, additional observation backhoe test pits shall be required.
(d) The following characteristics identify unsuitable soil conditions and if encountered, further evaluation is recommended and may be required:
(1) Munsell value of four (4) or more. Chroma of two (2) or less.
(2) Clean fractured rock - no weathering or fines.
(3) Massive crystalline rock structure, fractures more than five (5) inches apart.
(4) Massive clay or impervious layers within the absorptive area.
2. Percolation Tests
(a) The location of the percolation test holes should be evenly distributed horizontally and vertically in the proposed leaching area. The minimum number of test holes to be dug is four (4). Deep trench designs must be tested at varying depths for proper evaluation of soil.
(b) Dig or bore the test holes six (6) inches in diameter. The sides are to be kept as straight as possible. The shallowest hole shall be a minimum of eighteen (18) inches below proposed finish grade and maximum depth shall be within six (6) inches of design depth.
(c) Carefully scratch the bottom and sides of the hole with a sharp instrument to remove smeared soil particles, remove all loose soil material and then it is recommended you add two (2) inches of pea-size gravel to the bottom of the hole. Thoroughly wet the bottom and sides of the test hole by soaking at a minimum depth of twelve (12) inches. This is usually done overnight, except in very porous soils, or when the soil is already saturated due to wet conditions.
(e) Overnight Presoak Method
- After the minimum twelve (12) hour swelling period, add water to bring depth of water in the test hole to approximately six (6) inches above the bottom of the hole. Maintain approximately six (6) inches of water in the hole throughout the test. From a fixed reference point, measure the drop in water, level over thirty (30) minute intervals until the rate of drop stabilizes. Minimum time of test is 1.5 hours.
- If the water level drops at least six (6) inches in the first thirty (30) minute test interval, the time interval between measurements may be ten (10) minutes and the test run until the rate of drop stabilizes. Minimum time of test is one (1) hour.
(f) No Presoak Method
- If the test is to be done without a twelve (12) hour presoak, fill the holes with approximately six (6) inches of water. From a fixed reference point, measure the drop in water level at thirty (30) minute intervals. If the rate of drop is slow, longer intervals may be more appropriate. Maintain the depth of water in the hole at approximately six (6) inches. The test is to be run until a stabilized rate is established. Minimum time of test is four (4) hours.
- If the water level drops at least six (6) inches in the first thirty (30) minutes, the time interval between measurements shall be ten (10) minutes and the test run until the rate of drop stabilizes. Minimum time of test is 1.5 hours.
(g) A stabilized rate is when three (3) successive readings do not vary to any significant extent.
(h) Alternate methods of measuring the percolation rate may be approved by the Department if the proposed procedures can be shown to produce a stabilized rate as defined above.
(i) The percolation rate shall be calculated from the drop that occurs in the final time interval.
- Water carried sewage from bathrooms, kitchens, laundry fixtures, and other household plumbing shall pass through a septic, or other approved sedimentation, tank prior to its discharge into a disposal field.
- (1) The septic tank set level in place on undisturbed soil and a layer of approved bedding material may be used.
- (2) Septic tanks installed in areas subject to vehicular traffic shall be designed to support an H-20 AASHTO traffic loading.
- (3) Septic tanks shall not be installed in areas of high water table, unless specifically designed to account for this situation.
- (4) Septic tanks shall have a minimum soil cover of twelve (12) inches.
- (5) Fiberglass and Polyethylene Tank Requirements a. Shall be bedded on at least six (6) inches of sand or soil not containing large or sharp rocks.
- Shall be set level.
- Shall be bedded to the spring line with select material, hand tamped in not over twelve (12) inch lifts, or pond and jetted.
- Shall be covered from the spring line up with material that will no puncture the tank. Care shall be taken during placement to minimize settling.
- (6) Effluent filters are required in the sanitary tee on the outlet side of the septic tank.
4. Area of Disposal Fields
(a) Area of disposal fields shall be sized based on the proposed sewage flow and percolation rate. A minimum of three hundred (300) square feet absorption area shall be provided for each system exclusive of any hardpan, rock, clay or other impervious formations.
5. Leach Lines
(a) A standard leach line is considered to be three (3) feet wide and three (3) feet deep with a length as required.
(b) A non-standard leach line is wider, narrower, and/or deeper than three (3) feet with a length as required.
(c) Standard and deep trench systems shall be sized by the following formula:
Absorption area (A) = daily sewage flow divided by the application rate (Q)
Required absorption area shall be calculated by the following formula:
A = 2 (W + L) x (D - 1.5)
Where: Daily Sewage Flow = See Minimum Sewage Flows
T = stabilized percolation rate L = length of trenches
W = width of trenches D = depth of trenches
6. Minimum Sewage Flows
(a) Individual sewage disposal systems shall be designed to accommodate a sewage flow of 350 gallons per day plus 150 gallons for each additional bedroom. Apartments (up to 5 dwelling units), granny flats, and hardship mobile homes shall be calculated as follows:
Single Family Residence
1 Bedroom = 350 gpd
2 Bedrooms = 500 gpd
3 Bedrooms = 650 gpd
4 Bedrooms = 800 gpd
(b) Commercial Facilities
- (1) Projected daily flows for commercial facilities shall be estimated using Table 2. The Department may approve, on a case by case basis, metered water use data or other supporting data in lieu of the estimated sewage flows set forth in Table 2.
- (2) Commercial facilities that prepare foods, (e.g., kitchens, restaurants) shall install a grease trap or interceptor pursuant to the requirement the most recently Board adopted edition of the Uniform Plumbing and amendments thereto.
(c) Other design flows may be approved by the Director of Environmental Management upon submission of supporting data and calculations.
7. Distribution Standards
(a) Serial distribution shall be used for gravity fed systems where multiple trenches are utilized unless otherwise approved by the Department.
(b) Distribution boxes, when used, shall be installed to allow serial distribution to multiple leach lines. Only the terminating line may have excessive drop (greater than 6"). See Diagram # 5.
(c) Grouting material, when used, must be resistant to cracking and crumbling out of connection.
8. Abandoned Sewers and Sewage Disposal Facilities
(a) Every abandoned septic system, or part thereof, shall be plugged or capped in an approved manner.
(b) Every cesspool and septic tank which 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 there from and be completely filled with the earth, sand, gravel, concrete, or other approved material.
(c) The top cover or arch over the cesspool, septic tank, or seepage pit shall be removed before filling and the filling shall not extend above the top of the vertical portions of the sidewalls or above the level of any outlet pipe until inspection has been called and the cesspool, septic tank or seepage pit has been inspected. After such inspection, the cesspool, septic tank, or seepage pit shall be filled to the level of the top of the ground.
(d) No person owning or controlling any cesspool, septic tank, or seepage pit on the premises of such person or in that portion of any public street, alley, or other public property abutting such premises, shall fail, refuse, or neglect to comply with the provisions of this section or upon receipt of notice to comply from the Department having jurisdiction.
(e) Where disposal facilities are abandoned consequent to connecting any premises with the public sewer, the permittee making the connection shall fill all abandoned facilities as required by the Department within thirty (30) days from the time of connecting to the public sewer.
B. STANDARD SYSTEMS
1. Criteria for standard systems:
(a) Percolation rates between 5 and 30 min./in. with any depth of leach lines.
(b) Percolation rates between 30 and 60 min./in. for 3' x 3' leach lines.
Site evaluation criteria, design (including sizing), installation, and construction shall be in accordance with Section 1: General Provisions; Section 2-1: General Requirements; and Section 3: Construction and Materials.
C. SPECIAL DESIGN SYSTEM REQUIREMENTS
1. A special design system is any Department approved system that is not a standard system.
Conditions requiring special design include:
(a) Percolation rates greater than 60 min./in. for standard leach lines, greater than 30 min./in. for non-standard leach lines, or rates less than 5 min./in.
(b) Systems requiring a subsurface drain
(c) Off site systems requiring legal easement
(d) Capping Fill Systems
(e) Pressurized Distribution Systems
(f) Pump Systems
(g) Steep Slope Systems
(h) Sand Filter Systems
(i) Mound Systems
0) Package or Plant Systems
(k) All alternative or experimental systems
3. Unless otherwise indicated in specific special design sections or by the Department, site evaluation criteria, design (including sizing), installation, and construction shall be in accordance with Section 1: General Provisions; Section 2-1: General Requirements; and Section 3: Construction and Materials.
4. Special design systems will be accepted for review only from Registered Civil Engineers, Registered Geologists, Certified Professional Soil Scientists, or Registered Environmental Health Specialists who are knowledgeable and experienced in the field of sewage disposal system design and installation.
5. All special design sewage disposal systems shall require written certification by the designing Engineer, Geologist, Certified Professional Soil Scientists, or environmental Health Specialist that the sewage disposal system has been installed and completed, under his supervision, according to the approved plot plan. The written certification shall be a wet signature on the Environmental Health stamp (example below).
Special Design System
SPECIAL DESIGN SYSTEM
I hereby certify that this special design sewage disposal system has been installed and completed
under my supervision according to the approved plot plan and according to Chapter 6 of the
El Dorado County Building Ordinance.
6. Use of Fill in Sewage Disposal Area - The following are criteria which must be followed in developing fill for a leach field:
Area to receive fill must have vegetation removed.
(b) Area to receive fill must be plowed, ripped, scarified or disked on contour.
(c) The imported material shall have consistent characteristics as the native soil.
(d) Area to receive must or less than 20% slope, unless sites specific justification is made by the designer.
(e) Compaction test data shall be provided to ensure proper compaction to nearly the same degree as natural soil.
(f) Percolation rate of fill material must be equal to or slower than the percolation rate of native material.
(g) Compaction will be completed in six (6) inch lifts supervised by a Registered Civil Engineer, or another appropriately registered individual.
D. CAPPING FILL SYSTEMS (See Diagram 2)
1. A capping fill system is a special design system where the disposal trench effective sidewall is installed a minimum of twelve (12) inches into natural soil below a soil cap of specified depth and texture. The shallow construction of the system allows for installation where depth to fractured bedrock, a limiting layer, or groundwater is closer to ground surface. This section describes the requirements for gravity-fed capping fill system. Pressure-dosed capping fill systems shall meet the requirements of this Section as well as the section "Pressurized Distribution Systems".
2. In order to be approved for a capping fill system, each site must meet all of the following conditions:
(a) The slope shall not exceed twenty (20) percent in the disposal area and replacement area.
(b) Unless otherwise approved by the Department, the effective soil depth shall be a minimum of four (4) feet below the bottom of the disposal trench and depth to groundwater shall be four (4) feet.
3. Unless otherwise specified, the system shall be designed and installed in accordance with the provisions of Section 1: General Provisions; Section 2-1: General Requirements; and Section 3: Construction and Materials and the following:
(a) Disposal trenches - Depth: 12 inches minimum
Width: 18 inches minimum
36 inches maximum
(b) Cap depth: 12 inches minimum (after settling)
(c) The cap soil texture shall be of the same textural class as the natural topsoil, or of one textural class finer;
(d) The disposal area shall have the vegetation removed and shall be scarified, parallel to contours, and no deeper than six (6) inches;
(e) Soil cap shall extend a minimum of five (5) feet beyond the exterior trench sidewall and have a three (3) foot horizontal to one (1) foot vertical ratio to meet existing current requirements;
(f) The site shall be landscaped for erosion control in accordance with El Dorado County Department of Transportation/Resource Conservation District erosion control requirements;
(g) Capping Fill finish grade elevation shall be determined using an established bench mark to ascertain there is twelve (12) inches minimum fill.
4. Required inspections.
(a) The disposal area and fill material shall be inspected for scarification, soil texture, and moisture content.
(b) Prior to backfill of the installed disposal field.
(c) The final placement of the soil cap.
System sizing shall meet the minimum requirements of Section 2-A5.
E. PRESSURIZED DISTRIBUTION SYSTEMS (See Diagram 3)
1. Pressurized distribution refers to a method of distributing effluent evenly over the entire soil absorption area through a network of small diameter pipes under low pressure.
2. Pressurized distribution systems shall meet the following requirements:
(a) Pressurized distribution systems may be permitted on any site that meets the requirements for standard systems, or on sites approved for special design systems. The pressurized distribution system shall meet all the applicable requirements.
(b) The proposed disposal area and replacement area shall demonstrate a minimum of four (4) feet of effective soil depth beneath the disposal trench bottom.
3. Design, materials, and construction requirements.
(1) All materials used in pressurized systems shall be structurally sound, durable, and capable of withstanding normal stresses incidental to installation and operation.
(2) Nothing in these rules shall be construed to set aside applicable building, electrical, or other codes. An electrical permit and inspection from the local Building Authority shall be obtained if required for pump wiring installation.
(b) Criteria for system sizing. For systems where trench depth is less than 24inches, percolation tests shall be performed in the layer of most restrictive permeability that occurs within four (4) feet of the trench bottom. The deeper percolation test data shall be considered in the site evaluation design of the system.
(c) Pressurized distribution lateral requirements. Piping, valves, and fittings for pressurized systems shall meet the following minimum requirements:
(1) All pressure transport, manifold, distribution lateral piping and fittings shall meet or exceed the requirements for Schedule 40 PVC pressure pipe as identified in ASTM Specification D1785 or other material approved by the Department.
(2) All pressure distribution laterals and fittings shall be adequately sized for he design flow; a minimum of 2 foot/second velocity at the end of the system and a minimum three (3) foot residual head.
(3) All pressure transport and manifold piping shall be adequately sized for the design flow and minimum 2 foot/second velocity.
(4) Pressure transport piping shall be uniformly supported along the trench bottom, and at the discretion of the Department, it shall be bedded in sand or other material approved by the Department.
(5) The ends of lateral piping shall have blow-off risers that accommodate threaded plugs or caps, (Diagram 4).
(6) All joints-in the pressure distribution manifold, lateral piping, and fittings shall be solvent welded, using the appropriate solvent for the pipe material. Pressure transport piping may be solvent welded, threaded, or rubber ring jointed;
(7) A ball valve shall be placed on the pressure transport pipe, in-6f near the dosing tank, when required.
(8) A check valve shall be placed between the pump and the ball valve, when required. A check valve is not required if the pump has an internal check valve. All check valves and ball valves must be in an accessible and protected location for maintenance and repair.
(d) The pump shall meet the minimum design, materials, and construction standards for use in waste water applications.
(e) Dosing tank design, materials, and construction requirements.
(1) Materials and construction for dosing tanks shall comply with the minimum standards of Section 3-D.
(2) The minimum capacity of the tank shall be sufficient to deliver the design dose and shall have a minimum capacity of 500 gallons. The liquid capacity shall be measured from the invert elevation of the inlet fitting, to the bottom of the tank.
(3) The second compartment of the septic tank may be utilized as a dosing tank in areas serviced by a community services district or other public entity only under the following circumstances:
a. The system design will be considered a special design system. The float level elevations shall be clearly identified on the plan.
b. A minimum 1500-gallon septic tank will be used.
c. In no event shall the liquid portion be drawn down to within 12- inches of the tee fitting or baffle slot in the common compartment wall.
d. Pump must be located within a screened vault.
(4) The dose volume shall be calculated using the following minimum and maximum dosing range formulas:
Vmin Vs + 5VI
Vmax Vs + I OVI where: Vmin Minimum volume of dose
Vmax Maximum volume of dose
Vs = Volume of supply line
V1 = Total volume of lateral lines
Disposal trench design, materials, and construction requirements:
(1) Disposal trenches shall be constructed using the specifications for the standard disposal trench, except for the following:
a. Pressure lateral piping shall have a minimum six (6) inches of filter material below, and not less than one inch of filter material above the piping and;
b. Depth: minimum 12 inches
c. Bottom width: maximum 36 inches
d. Length of lateral shall be limited to that length which will result in no more than a 10% head loss over the length of the lateral.
(2) The top of the filter material shall be covered with filter fabric or other material approved by the Department.
(3) A minimum of 12 inches of backfill is required over the soil barrier material within the disposal trench.
(4) Inspection and blow-off risers constructed in accordance with Diagram 4 shall be placed at the end of the pressure distribution lateral within the disposal trench.
(5) All orifices of pressure distribution laterals shall face upward and shall be covered with orifice shields to prevent soil washout.
4. Hydraulic design criteria.
(a) There shall be a minimum six (6) feet head (squirt) at the most remote orifice and no more than ten (10) percent head variation between the most near and remote orifices within a disposal field.
(b) Lateral piping shall have discharge orifices drilled upward, a minimum diameter larger than screen filter holes of one-eighth (1/8) inch, and evenly spaced at a distance not greater than two (2) feet in coarse textured soils or greater than six (6) feet in finer textured soils.
5. Unless otherwise indicated on the permit or elsewhere in this Section, the installation standards of Section 1: General Provisions; Section 2-1: General Requirements; and Section 3: Construction and Materials shall apply, and:
(a) The pressure distribution lateral laid within the center of the trench above the gravel shall be level to within two (2) inches in one hundred (100) feet.
(b) Each dosing tank shall be installed on a stable level base;
(c) Each dosing tank shall be provided with a watertight riser extending to the ground surface or above, with a minimum inside horizontal measurement equal to or greater than the tank access manhole. The watertight riser shall meet the materials and construction provisions in the section for septic tanks; and
(d) Dosing tanks located in high groundwater areas shall be weighted or secured to prevent flotation.
6. Sloping site requirements.
(a) Ball valves or flow restricters shall be installed on each pressure distribution lateral to facilitate regulation of flow within each lateral.
(b) Where the disposal field is located down slope from the pump, an anti-siphon device placed at the highest point on the supply line to the trenches shall be installed in the dosing tank.
7. Additional required inspections include the following:
(a) Inspection of the dosing system components, e.g., the location of the pump, screen, switches, alarms, and valves; and
(b) Inspection of the pressure distribution system and verification of hydraulic head over the pressure distribution laterals.
F. PUMP SYSTEMS
1. A pump system is utilized to enable the installation of a disposal field up slope of the structure to be served. The effluent is distributed to the disposal field by gravity flow following pumping to a higher elevation. Pressure-dosed pump systems shall meet the requirements of this Section as well as the section "Pressurized Distribution Systems".
Criteria for approval
(a) Drainage from septic tanks located below the level of the disposal field shall discharge into a separate, approved, watertight sewage disposal system pump well. The sewage disposal system pump well shall receive septic tank effluent only.
(b) The drainage and venting systems, in connection with the sewage disposal system pump well, shall be installed under the same requirements as for gravity systems.
(c) All pump systems shall have a surge tank or D-box to intercept pumped effluent prior to distribution into drain fields.
(d) Districts maintained by a public entity will follow their approved guidelines.
(e) Unless otherwise indicated on the permit, installation requirements shall be as in Section 1: General Provisions; Section 2-1: General Requirements; Section 3: Construction and Materials and pressurized distribution systems (with application as a pump tank, not dosing tank).
3. Pump Tank Requirements
(a) When a wet well or sump pump is used, the septic tank capacity must be adequate to handle such instantaneous flows.
(b) The sewage disposal system pump well shall be so located as to receive the sewage waste by gravity drainage.
(c) Sewage disposal system pump wells shall be watertight and shall be constructed of approved materials. Sewage disposal system pump well tanks shall be constructed in accordance with specifications for septic tanks. The lids to the pump wells shall be water and gas tight, accessible, but child proof.
(d) The pump tank shall have capacity sufficient to deliver the design dose and have a minimum capacity of 500 gallons.
(e) Each pump tank shall be provided with a watertight riser extending to the ground surface or above, with a minimum inside horizontal measurement equal to or greater than the tank access manhole. Provision shall be made for securely fastening the watertight manhole cover.
(f) Pump tanks in high groundwater areas shall be weighted or secured to prevent flotation and watertight.
(g) The second compartment of the septic tank may be utilized as a dosing tank only in areas serviced by a community services district or other public entity under the following circumstances:
(1) The system design will be considered a special design system. The float level elevations shall be clearly identified on the plan.
(2) A minimum 1500-gallon septic tank will be used.
(3) In no event shall the liquid portion be drawn down to within 12 inches the tee fitting or baffle slot in the common compartment wall.
4. Piping Requirements
(a) The drainage piping connecting the septic tank and the sewage disposal system pump well shall be at least three (3) inches in diameter.
(b) The pump discharge piping shall be sized to adequately handle all expected flows.
(d)The discharge piping shall be provided with an accessible check valve and ball valve.
Class 200 PVC water pipe or equivalent must be used.
(e)Velocities shall be maintained between 2 - 10 feet/second.
5. Mechanical Devices Requirements
(a) Check valves, ball valves, pumps, motors, switches, and other mechanical devices required by this Section shall be located where they will be readily and easily accessible for inspection and repair at all times, unless continuously exposed, and shall be enclosed in a watertight pit fitted with an adequately sized removable cover.
(b) Check valves, ball valves, pumps, motors, switches, and other mechanical devices shall be designed and manufactured to operate in septic tank effluent or sewage.
(c) Pumps shall be approved by the Department. The pumps shall be made specifically for sewage.
(d) All devices and equipment associated with sewage disposal system pump wells, which are exposed to the elements shall be protected by a weather-proof structure.
(e) All pumps shall be equipped with a high water alarm system.
(f) Pump control panel shall have a cycle counter and an elapsed time meter.
6. Inspection Requirements
(a) Open trenches will be inspected by the consultant. The Department will inspect the final system.
(b) Pump systems shall be operating at the time of final inspection. Inspection will be done by the consultant and the Department.
G. STEEP SLOPE SYSTEMS
1. A steep slope system is a system installed on sites with slopes greater than thirty (30) percent.
2. A steep slope system shall meet the following requirements:
(a) Steep slope systems are always special design systems.
(b) The designer must address distance from trench side wall to soil surface (side wall break out distance) and it must be a minimum of twenty four (24) inches to flow line as measured on the downhill side.
(c) Steep slope systems will not be approved on unstable land forms.
H. INTERMITTENT AND RECIRCULATING SAND FILTER SYSTEM REQUIREMENTS
1. An intermittent sand filter system consists of a septic tank, dosing tank, sand filter bed, and a disposal field. Effluent is periodically dosed to a bed of sand media and discharged into a disposal field via an under drain. This type of system is used to mitigate the limitations associated with shallow effective soil depth, soils with rapid permeability, and very slowly permeable soils.
2. An intermittent or re-circulating sand filter system may be considered on a case by case basis.
3. The sand fill shall meet all the following criteria:
(a) A granular mineral material, other than limestone.
(b) Total acid soluble matter shall be less than three (3) percent.
(c) The uniformity coefficient shall be 4.0 or less.
(d) The minimum effective size shall be at least .3mm and not more than 1.0mm. (maximum).
(e) The material shall have four (4) percent or less passing the #100 sieve.
(f) Fibrous or platy material is unacceptable.
(g) Certification of sand specifications must be provided by the sand supplier to the designer that it meets the above minimum criteria.
I. MOUND SYSTEM REQUIREMENTS
1. A mound system is an aboveground absorption facility useful in mitigating some of the limitations associated with inadequate effective soil depth. The mound system consists of a distribution network that, under pressure, evenly delivers effluent from a septic tank to a "mounded" bed of filter material over sand media.
2. The mound design and system shall meet the minimum requirements of the Department and the provisions of the State Water Resources Control Board, Guidelines for Mound Systems most current version, and amendments thereto. The following provisions shall supersede any conflicting provisions of the Guidelines for Mound Systems that shall be met:
(a) An absorption rate of 1.2 gallons per day per square foot (based on 220 gallons per bedroom per day) shall be used for calculating the mound sand bed area,
(b) Sand media as defined in section Diagram 12 of these regulations shall be used for the sand bed,
(c) Unless otherwise approved, a mound system shall only be considered for use for a single-family dwelling.
J. PACKAGE PLANT SYSTEMS
1. A package plant system is defined as a proprietary self-contained wastewater treatment and disposal system.
2. Criteria for Approval
(a) A package plant system may be considered on a case by case basis.
(b) These systems will only be considered in areas serviced by a community services district or other public entity.
(c) The system must be approved by the State of California Water Quality Control Board - Central Valley Region.
K. GRAYWATER SYSTEM REQUIREMENTS
1. Gray water systems shall be designed, constructed and installed in accordance with the most current California Gray water Standards adopted by the State of California.
L. EXPERIMENTAL SYSTEM REQUIREMENTS
1. Experimental sewage disposal systems are those designs which do not conform with the design standards.
2. Experimental systems may be approved by the Director of Environmental Management on a case by case basis when the following conditions have been met: It
(a) The system must be installed in an area serviced by a community services district or other public entity.
(b) The experimental system can be installed on property shown to be suitable for a conventional system.
(c) Adequate data must be supplied to justify the reliability of such designs.
(d) A program of monitoring and evaluation must be established to determine the proper functioning of the system and a biannual report on the system shall be provided.
M. LARGE SYSTEM REQUIREMENTS
1. A large system is a system with a projected daily sewage flow greater than two thousand five hundred (2,500) gallons, or has waste characteristics other than typical residential, from one residential or commercial facility.
2. Unless otherwise authorized by the Department, designs for large systems shall at a minimum meet all of the following:
(a) The disposal and replacement areas shall be divided into a minimum of two (2) disposal fields.
(b) Effluent distribution shall alternate between the disposal fields.
(c) If the system is pumped, it shall have at least two (2) alternating pumps.
(d) Unless otherwise specified, septic tank design, materials, and construction shall conform to the provisions of this resolution.
N. AEROBIC SYSTEM REQUIREMENTS
1. Approved aerobic systems may be substituted for conventional septic tanks provided the Director of Environmental Management is satisfied that such systems will produce results at least equivalent to septic tanks, whether their aeration systems are operating or not.
0. HOLDING TANKS AND CESSPOOLS
1. Holding tanks, cesspools, and other sewage disposal systems requiring drained or pumped removal from the premises and transportation by vehicle for disposal shall not be allowed and are prohibited.
EXCEPTION: A pre-existing, approved holding tank will be allowed continued use. Any change to that approval shall be at the discretion of the Director of Environmental Management.
Section 3 - Materials and Construction
All sewage disposal systems must be installed by a licensed contractor, holding an A, C12, C42, license.
A. SEPTIC TANK REQUIREMENTS
1. The liquid capacity of all septic tanks shall conform to Table 4 as determined by the number of bedrooms or apartment units in dwelling occupancies, and the estimated waste/sewage design flow rate or the number of plumbing fixture units as determined from Table 3, whichever is greater.
2. Design Requirements
(a) Plans for all septic tanks shall be submitted to the Director of Environmental Management for approval. Such plans shall show all dimensions, reinforcing structural calculations, and such other pertinent data as may be required.
(b) Septic tank's design shall be such as to produce a clarified effluent consistent with accepted standards and shall provide adequate space for sludge and scum accumulations.
(c) Each such tank shall be structurally designed to withstand all anticipated earth or other loads. All septic tank covers shall be brought to grade, using the appropriate water tight gaskets and capable of supporting an earth load of not less than three hundred (300) pounds per square foot when the maximum coverage does not exceed three (3) feet.
(d) Septic tanks installed under concrete or black top paving shall have the required manholes accessible by extending the manhole openings to grade in a manner acceptable to the Director of Environmental Management.
(e) All tanks will be fitted with an approved filter on the effluent side of the tank.
(a) Septic tanks shall be constructed of solid durable materials, not subject to excessive corrosion or decay and shall be watertight.
(b) Septic tanks shall have a minimum of two (2) compartments. The inlet compartment of any septic tank shall be not less than two-thirds (2/3) of the total capacity of the tank and shall be at least three (3) feet in width and five (5) feet in length. Liquid depth shall be not less than two (2) feet and six (6) inches nor more than six (6) feet. The secondary compartment of any septic tank shall have a maximum capacity of one-third (1/3) of the total capacity of such tank. In septic tanks having over fifteen hundred (1500) gallons capacity, the secondary compartment may be not less than (5) feet in length.
(c) Access to each septic tank shall be provided by at least two (2) manholes twenty (20) inches in minimum dimension or by an equivalent removable cover slab. One access manhole shall be located over the inlet and one (1) access manhole shall be located over the outlet and brought to grade. Wherever a first compartment exceeds twelve (12) feet in length, an additional manhole shall be provided over the baffle wall.
(d) The side walls shall extend at least (9) inches above the liquid depth. The cover of the septic tank shall be at least two (2) inches above the back vent openings.
(e) Partitions or baffles between compartments shall be of solid durable material and shall extend at least four (4) inches above the liquid level. An inverted fitting equivalent in size to the tank inlet, but in no case less than four (4) inches in size, shall be installed in the inlet compartment side of the baffle with the bottom of the fitting placed midway in the depth of the liquid. Wooden baffles are prohibited.
(f) Alternate Materials
(1) Septic tanks constructed of alternate materials may be approved by the Director of Environmental Management when complying with approved applicable standards.
(2) Wooden septic tanks are prohibited.
(g) Prefabricated Septic Tanks
(1) Manufactured or prefabricated septic tanks shall comply with all approved, applicable standards and be approved by the Department.
(2) Independent laboratory tests and engineering calculations certifying the tank capacity and structural stability shall be provided as required by the Director of Environmental Management.
(h) Cast-in-place septic tanks may be considered on a case-by-case basis. These septic tank designs shall be reviewed by the Department, and may require a permit from the Building Department.
(a) The inlet and outlet pipe openings shall be not less in size than the connecting sewer pipe. The vertical leg of a round inlet and outlet fitting shall not be less in size than the connecting sewer pipe. A baffle type fitting shall have the equivalent cross-sectional area of the connecting pipe and not less than four (4) inch horizontal dimension when measured at the inlet and outlet pipe inverts.
(b) The inlet and outlet pipe or baffle (sanitary tee) shall extend four (4) inches above and at least twelve (12) inches below the water surface. The base of the inlet pipe shall be at a level not less than two (2) inches above the base of the outlet pipe.
(c) Inlet and outlet pipe fittings or baffles, and compartment partitions shall have a free vent area equal to the required cross-sectional area of the house sewer or private sewer discharging therein to provide free ventilation above the water surface from the disposal field or seepage pit through the septic tank, house sewer, and stack to the outer air.
B. SERIAL DISTRIBUTION MATERIALS AND CONSTRUCTION (See Diagram 5)
1. Distribution Box
(a) Distribution boxes shall be constructed of concrete, fiberglass, or other materials acceptable to the Department.
(b) Distribution boxes shall be watertight, and designed to accommodate the necessary distribution laterals and expected flows. The top, walls, and bottom of concrete distribution boxes shall be at least one and one-half (1-1/2) inches thick.
(c) Distribution box flow shall be in accordance with Diagram 10.
(d) All distribution boxes shall be bedded level on undisturbed soil or on concrete.
2. Pipe Fitting Distribution
(a) Pipe fittings shall meet the minimum standards established in Section 3-e.
(b) Pipe fittings shall be located within the disposal trench, firmly bedded in the filter material. See Diagram 8.
(c) All joints shall be glued so as to be watertight.
C. DIVERSION VALVE MATERIALS AND CONSTRUCTION
1. Diversion valves shall be constructed of durable material and be corrosion-resistant, watertight, and designed to accommodate the inlet and outlet pipes.
2. Each diversion valve shall be approved by the Department.
D. EFFLUENT PUMP, CONTROL, AND ALARM MATERIALS AND CONSTRUCTION (See Diagram 6)
1. Unless otherwise specified, effluent pump, control box, and alarm materials and construction shall, at minimum, be in conformance with this section.
2. Electrical components used in systems shall comply with the Uniform Electrical Code, and the following provisions:
(a) Motors shall be continuous-duty, with overload protection.
(b) Pumps shall have durable impellers of bronze, cast iron, or other materials approved by the Department.
(c) Submersible pumps shall be provided with an easy, readily accessible means of electrical and plumbing disconnect, and a non-corrosive lifting device as a means of removal for servicing.
(d) For pressure distribution systems, a corrosion-resistant screen shall protect the pump. The screen shall have at least twelve (12) square feet of surface area, with one-eighth (1/8) inch openings. The use of a screen is not required if the pump does not discharge into a pressurized distribution system, and the pump has a non-clog impeller capable of passing a 3/4 inch diameter solid sphere.
(e) Pumps shall be automatically controlled by sealed mercury float switches with a minimum mercury tube rating of twelve (12) amps at one hundred fifteen (115) volts AC or by a Department-approved equivalent.
(f) Pumps shall have automatically resetting audible and visual high water level alarm with manual silence switch that is located in or near the building served by the pump. The audible alarm may only be canceled by the user.
(g) Wiring must be of proper construction and gauge and permanently fixed to a supporting structure under permit from the local Building Authority.
(h) The pump and alarm must be connected to separate circuits.
(i) Pump control panel shall have a cycle counter and an elapsed time meter.
(j) There shall be a manual override switch in the electrical box to facilitate dosing control during inspections.
E. PIPE MATERIALS AND CONSTRUCTION
1. Unless otherwise specified, piping shall, consist of materials and be constructed in conformance with the standards of this section. All piping shall be free of defects or damage. All connection of pipes of different diameters shall be made with the proper fitting.
2. Effluent sewer pipe, header pipe, and fittings (all tight line). Header pipe shall extend a minimum of five (5) feet out of the distribution box. Effluent sewer and header pipe and fittings shall be a minimum four (4) inch diameter, watertight and one of the following:
(a) Schedule 40 PVC that meets the most current ASTM D-2672 for minimum four (4) inch pipe.
(b) Schedule 40 Acrylonitrile-Butadiene-Styrene (ABS) that meets the most current ASTM Specification D-2468;
(c) ASTM SDR 3 5 with solvent-welded or rubber-gasketed joints.
(d) Other material approved by the Department.
3. Perforated distribution piping. Distribution piping for gravity flow systems shall be a minimum four (4) inches diameter 3000 HDPE or equivalent that meets the most current ASTM Specifications F-810, or other material approved by the Department. The pipe described above shall have two (2) rows of holes spaced one hundred-twenty (120) degrees apart and sixty (60) degrees on either side of a centerline facing down.
4. Pressure Transport Pipe, Pressure Distribution Manifolds, and Pressure Distribution Laterals. Pressure transport pipe, pressure distribution manifolds, and pressure distribution lateral (piping and fittings), shall meet the most current requirements for schedule 40 PVC pressure pipe as identified in ASTM Specifications D-1785, or other material approved by the Department. All pressure distribution laterals and all pressure transport and manifold piping shall be adequately sized for the design flow.
F. CURTAIN DRAIN DESIGN, MATERIALS AND CONSTRUCTION (See Diagram 7)
1. Unless otherwise approved, a curtain drain shall meet the minimum requirements as follows:
(a) All curtain drains shall be designed by a consultant and generally conform to the requirements of special design systems.
(b) Curtain drains shall be fifteen (15) feet uphill from the disposal area and the outflow must be fifty (50) feet from the disposal and repair area.
(c) All other requirements for system approval, except depth to groundwater, can be met. However, after the drain is installed, the groundwater levels- shall conform to the requirements for vertical separation to groundwater for the proposed system.
(d) The site will allow discharge to the ground surface.
(e) The Department has the discretion of requiring demonstration that a proposed curtain drain is effective prior to issuing a permit.
2. Design, construction, and materials requirements for curtain drains.
(a) The trench shall be installed up slope of the disposal area to be protected.
(b) The trench shall be situated so that captured water drains by gravity-flow out of outlet pipes. Trench bottoms shall maintain a minimum of one (1) percent slope throughout the drainage trench. In areas where the outlet pipe will be subject to damage, the pipe shall be adequately protected.
(c) The trench shall be a minimum of twelve (12) inches wide. For. a curtain drain, it shall extend from ground surface at least 6 inches into a limiting layer. For a vertical drain, the trench shall penetrate through the limiting layer into a permeable soil.
(d) The bottom and the downhill side of the trench may be lined with a waterproof barrier: Material utilized must be two layers of six mil plastic waterproof barrier. The waterproof barrier is to be placed along the downhill side of the trench wall and at the bottom of the trench.
(e) A four (4) inch minimum Polyvinyl Chloride (PVC) or Polyethylene (PE) perforated pipe shall be laid the entire length of the trench with two (2) inches of gravel underneath the pipe.
(f) The drain shall be filled with drain rock. Prior to backfilling the trench, the drain rock shall be covered with filter fabric. A minimum of six (6) inches of soil cover shall be placed over each trench.
3. In the event that the discharge outflow from a curtain drain will impact a neighboring property, the trench outlet from a curtain drain shall only discharge into a drainage channel or other conveyance designed for the transport of water, unless otherwise approved by the Department.
G. LEACH LINE CONSTRUCTION
1. Design Requirements
(a) Leach lines shall not be installed on a slope greater than thirty (30) percent without special engineering.
(b) Leach lines may be used under asphalt or concrete paving with special engineering.
(c) Gravel-less trench construction may be utilized instead of drain rock in the disposal trench. The design, manufacturing, and materials used shall be durable and acceptable to the Department. Sizing for gravel-less disposal trenches shall be done using one of the following options:
(1) Absorption area calculated using side wall and bottom area.
(2) Absorption area calculated using side wall area with a 25% reduction. NOTE: Side wall area for gravel-less chambers shall be calculated from the top of the ribs to the bottom of the trench.
(a) Disposal fields shall be constructed as follows:
Maximum length of each line 100 ft.
Minimum spacing of lines, enter-to-center 10 ft.
Minimum filter material over drain lines2 in.
Minimum trench width 8 in.
Tight line must have minimum slope of 1/8 in./ft.
Minimum depth of natural earth over all lines as measured from the lowest point of natural grade 12 in.
Maximum "drop" in leach line (bottom of trench and drain pipe) 3 in./I 00'
Drain line pipe ends must be capped, holes in pipe must face downward
A minimum of one observation riser shall be installed at the, end of each trench.
(b) Drain Rock shall be clean, sound gravel or crushed rock ranging in size from 3/4 to 1 1/2inch diameter, with <5% outside this range.
(c) Leach lines shall be constructed of approved material as referenced in section 3-5. All bends and connections used in the disposal field shall be made with appropriate fittings. The mitering of drain pipe is not acceptable. Leach line piping shall be installed tight with no open joints and capped at end.
(d) All smeared or compacted surfaces shall be removed from trenches by raking to a depth of one (1) inch and then removing the loose material. Clean drain rock conforming to specifications stated in this section shall be placed in the trench to the depth and grade required by the design. Drain pipe shall be placed on drain rock level or with a down slope not to exceed 3 " in 100'. The drain lines shall then be covered with a minimum 2" of drain rock, then covered with an approved soil barrier cover of filter fabric, untreated paper, or straw to prevent closure of voids with earth backfill. No earth backfill shall be placed over the soil barrier cover until after inspection and approval.
(e) Connections between a septic tank and a distribution box, or between a distribution box and a leach line, shall be laid with schedule 40 or SDR 35, having watertight joints on natural ground.
(f) Tight line under driveways shall be Schedule 40, SDR 35 or other approved pipe with at least twelve (12) inches of natural soil cover.
(g) Multiple disposal field laterals, wherever practical, shall be of uniform length.
(h) Where two (2) or more drain lines are installed, distribution boxes or pipe fitting distribution shall be provided in accordance with Diagram 8 and Diagram 10. Distribution boxes shall be installed on native soil with a five (5) foot separation from leach lines by an undisturbed soil platform.
(i) Serial distribution is to be utilized on sloping ground. Each horizontal leaching trench shall be utilized to the maximum capacity before the effluent shall pass to the next lower leach line. The lines between each horizontal leaching section shall be made with watertight joints.
(j) Suspended tight line crossing streams or drainage courses shall be piped and shall be installed within a protective sleeve of approved material that extends ten (10) feet on each side of the seasonal or high water mark for the seasonal drainage course or twenty five (25) feet for a year-round stream. Crossings above streams or drainage courses shall be designed to support the weight of the sleeve, the tight line flowing full, and other loading conditions as set forth in the Uniform Building Code. Crossings above the stream or drainage course shall be installed l' above the 100 year recurrence interval high water level.
H. COMMERCIAL OR INDUSTRIAL SPECIAL LIQUID WASTE DISPOSAL
1. Effluent containing high strength waste which may effect the satisfactory functioning of an on site waste disposal system shall have pretreatment devices; example, interceptor tank.
2. Liquid waste containing hazardous substances may not be discharged into a subsurface on site sewage disposal system.
3. To determine size of pretreatment device, see Table 5.
4. A minimum of a 500-gallon ground grease trap will be required on all grease producing commercial establishments.
Section 4 - Appendices
1. Definition of Terms.
Abandoned septic system: A septic system that will no longer be used to receive effluent because the dwelling has been connected to an approved sewer system or the Division of Environmental Health has issued a notice or order to abandon the system.
Abandoned well: A well whose original purpose and use has been permanently discontinued or which is in such a state of disrepair that it cannot be used for its original purpose. If an abandoned well has been properly destroyed so that it will not produce water nor act as a conduit for the movement of water, it will not be subject to well setback requirements.
Alteration: Expansion and/or modification of an existing system, or any part thereof.
American Society for Testing Materials (ASTNI): A technical organization with headquarters located at 1916 Race Street, Philadelphia, Pennsylvania, 19103, which publishes national standards for the testing and quality assurance of construction materials.
Applicant: An owner or owner's authorized representative.
Artificial Drain: Any artificial drainage feature or structure that intercepts and concentrates groundwater or surface water. For example: driveways, roads, road ditches, agricultural drain tile, cut banks, and curtain drains.
At Grade System: See capping fill system.
Bedrock: Unweathered solid rock that is impermeable or has less than 15% porosity. If present, fractures are tight, dry, and cemented.
Bedroom: Any room designated as such by the local Building Authority having jurisdiction.
Black water: Human or commercial kennel wastes including feces, urine, the carriage water generated through toilet usage, other extraneous substances of body origin, toilet paper and wastes discharged from kitchen sinks and dishwashers.
Building Sewer: That part of the system or drainage piping which conveys sewage from a building to the septic tank or public sewer.
Building Site: This resolution adopts by reference the definition as it appears in the El Dorado County Land Use and Development Code and amendments thereto.
Capping Fill System: A gravity fed or pressure dosed special design system where the disposal trench effective sidewall is installed a minimum of twelve (12) inches into natural soil below a soil cap of specified depth and texture.
Chemical Toilet Facility: A non-flushing, non-recirculating toilet facility wherein backwater is deposited directly into a chamber containing a solution of water and chemicals.
Claypan: A dense, compact layer in the subsoil having a much higher clay content than the overlying material, from which it is separated by a sharply defined boundary. Claypans are usually hard when dry and plastic and sticky when wet. Also, they usually impede the movement of water and air, and the growth of plant roots.
Commercial Facility: Any structure or building, (excluding single-family residential units), or any portion thereof, intended for commercial or industrial use.
Community System: A system which serves more than one (1) lot or parcel.
Consultant: One of the following persons (exclusive of Department personnel)
(a) Registered Environmental Health Specialist,
(b) Registered Geologist,
(c) Registered Civil Engineer
Contractor: A person who possesses an active Class A, B-1 or C-42 contractor's license in accordance with the provisions of the California Business and Professions Code.
Curtain Drain: An artificial drain installed up slope from a disposal field to intercept and divert ground water.
Cut: A land surface resulting from mechanical land shaping.
Department: The El Dorado County Department of Environmental Management, Division of Environmental Health and its designated employees.
Deep Trench System: A system with disposal trenches greater than thirty (36) inches deep.
Design Capacity: The maximum quantity of daily sewage flow that a system is designed to handle.
Design Daily Sewage Flow: The quantity of daily sewage flow assigned to a building or structure.
Director: The Director of the El Dorado County Department of Environmental Management. This position also functions as Deputy Health Officer.
Disposal Area: The entire area used for underground dispersion of the liquid portion of sewage. Disposal Field: A system of disposal trenches.
Disposal Trench: A ditch or trench with vertical sides and substantially flat bottom designed to
receive sewage effluent.
Distribution Box: A structure which receives effluent and distributes it to the disposal area.
Distribution Pipe or Lateral Pipe: A perforated pipe used in the dispersion of effluent into disposal trenches.
Distribution Unit: A distribution box, crossover unit, dosing tank, diversion valve or box, header pipe, effluent lift pump or other means of transmitting effluent from the effluent sewer to the distribution pipes.
Domestic Waste: Wastewater generated by either residential or commercial uses. This includes Gray water, backwater, agricultural processing wastewater, and winery processing wastewater.
Dosing Tank: A watertight receptacle designed to periodically discharge treated effluent placed after a septic tank.
Drain Rock: Clean, sound gravel or crushed rock ranging in size from 3/4 to I 1/2inch diameter, with <5% outside this range.
Dwelling: Any structure or building or any portion thereof which is used, intended, or designed to be occupied for human living purposes including, but not limited to, houses, houseboats, boathouses, mobile homes, travel trailers, hotels, motels, and apartments.
Effective Absorption Area: The sidewall area below the distribution area, except for gravel-less chambers.
Effective Soil Depth: The depth of soil material from ground surface that effectively provides filtration of effluent. Effective soil excludes soil layers that meet the criteria for "Soil with rapid permeability" (<5 m.p.i.), "Conditions associated with saturation" and "Limiting Layers" (<15% porosity).
Effluent: The partially treated, liquid portion of sewage.
Effluent Lift Pump: A pump used to lift effluent to a higher elevation.
Effluent Sewer: That part of the system of drainage piping that conveys sewage effluent from a septic tank or other treatment facility into a distribution unit or a disposal area.
Ephemeral Stream: See intermittent stream.
Escarpment: Any naturally occurring slope which extends nearly vertical, and which is characterized by a long cliff or steep slope which separates two (2) or more comparatively level or gently sloping surfaces, and may intercept one (1) or more layers that limit effective soil depth.
Existing lot or parcel: A lot or parcel legally created prior to the effective date of this ordinance. Existing System: Any installed system constructed in conformance with the rules, laws and local ordinances in effect at the time of construction.
Expansive Clay Soil: Mineral soil that swells and shears when wet, and shrinks and develops cracks when dry, forming slickensides and wedge-shaped structure. Expansive clay soil is very hard or extremely hard when dry, very firm when moist, and very sticky and very plastic when wet. When wet, expansive clay soil is massive and cracks and structure are not evident.
Experimental System: An on-site sewage disposal system of technological innovation, not represented in this resolution. The system must be recognized and approved by the Department of Environmental Management, Division of Environmental Health.
Failing Septic System: Any system which discharges untreated or inadequately treated sewage or septic tank effluent directly or indirectly onto the ground surface, into public waters, or into a dwelling.
Fractured Bedrock: Moderately to slightly weathered bedrock that usually is hard and fractured, but not impermeable to water.
Gravel-less disposal field: Prefabricated chambers used in leach field disposal fields as filter media instead of gravel (drain rock).
Gray water: Untreated wastewater (sewage) which has not come into contact with toilet wastes. It includes used water from bathtubs, showers, bathroom wash basins, and from clothes washing machines and laundry tubs. It does not include wastewater from kitchen sinks, dishwashers or laundry water from soiled diapers.
Gray water Disposal System: An on-site sewage disposal system consisting of a tank and shallow disposal field meeting the requirements of the State Gray water Law.
Groundwater: A layer or lens of soil or fractured bedrock in which all open spaces are filled with water. The thickness and extent of groundwater may vary seasonally or periodically in response to changes in the rate or amount of groundwater recharge or discharge.
Header Pipe: The tight jointed part of the sewage drainage conduit which receives septic tank effluent from the distribution box, crossover unit or effluent sewer and conveys it to and within the disposal area.
High Line System: See capping fill system.
Holding Tank: A watertight receptacle designed to receive and store sewage to facilitate disposal at another location.
Horizon: See soil horizon
Individual System: A system that is not a community system and serves only one lot or parcel. Installer: See contractor.
Intermittent Stream (ephemeral stream, seasonal stream): A natural stream that does not flow continuously throughout the year, but that has a well-defined channel of stream gravel or bedrock control.
Invert: The lowest portion of the internal cross section of a pipe or fitting.
Limiting Layer: A layer that prevents the movement of water, air, or the growth of plant roots.
Monitoring Well (observation riser): Any artificial excavation by any method for the purpose of monitoring fluctuations in ground water levels, quality of underground water, or the concentration of contaminants in underground water.
Mottled soils: Soils irregularly marked with spots that vary in color, number and size.
Mound System: An above-ground system that consists of a pressure distribution network that evenly distributes sewage effluent to a "mounded" bed of filter material over sand media.
Non-expansive clay: Clay soil that does not demonstrate expansion when wetted. Properties of plasticity, cohesion, shrinkage, and swelling are negligible.
Owner: Any person who alone, or jointly, or severally with others:
(a) Has legal title to any single lot, dwelling, dwelling unit, or commercial facility;
(b) Has care, charge, or control of any real property as agent, executor, executive administrator, administrative trustee, commercial lessee, or guardian of the estate of the holder of legal title; or
(c) Is the owner's authorized representative.
Owner's Authorized Representative: A person authorized in writing by an owner or easement holder of the land on which the system is to be installed, to represent the owner's interests (e.g., consultant, contractor, real estate agent, etc.).
Occupant: Any person living,or sleeping in a dwelling.
Percolation Test: A measurement of the ability of the soil to absorb liquid.
Perennial Stream: A natural stream where water is present nine (9) months or more of the year, including all irrigation ditches and other public water conveyances.
Permit: The written document issued and signed by the Division of Environmental Health, which authorizes the permittee to construct a system or any part thereof.
Person: Includes individuals, corporations, associations, firms, partnerships, joint stock companies, public and municipal corporations, political subdivisions, cities, counties, the State and any agencies thereof, and the Federal government and any agencies thereof
Pipe Fitting Distribution (Crossover Unit): A series of pipe fittings connected to the distribution pipe providing serial distribution of effluent in the disposal field. See diagram 8.
Pit Privy: A structure for collection of human waste without the aid of water. It consists of a shelter built above an excavated pit into which human waste falls. The pit privy has no direct water connection.
Pollution: The undesirable change in the physical, chemical, or biological characteristics of air, land, and water that may or will harmfully affect human life or that of other desirable species, industrial processes, living conditions, and cultural assets; or that may or will waste or deteriorate raw material resources.
Portable Toilet: Any self contained chemical toilet facility that is housed within a portable toilet shelter. The portable toilet has no direct water connection.
Portable Toilet Shelter: Any easily moved structure built to house a toilet facility.
Pressure Distribution Lateral: Piping and fittings in pressure distribution systems which distribute effluent to filter material through small diameter orifices.
Pressure Distribution Manifold: Piping and fittings in a pressure distribution system which supply effluent from pressure transport piping to pressure distribution laterals.
Pressure Distribution System: Any system designed to uniformly distribute effluent under pressure in a disposal area.
Pressure Transport Piping: Piping which conveys effluent to a pressure distribution manifold.
Prior Approval: A written approval for on-site sewage disposal, for a specific lot, issued prior to the effective date of this ordinance.
Public Entity: A local agency, as defined in the State of California Government Code Section 53090 et. seq., which is empowered to plan, design, finance, construct, operate, maintain, and to abandon, if necessary, any sewerage system or the expansion of any sewerage system and sewage treatment facilities serving a land development.
Public Health Hazard: A condition created by a discharge of biological, chemical, physical, and/or radiological agents which are likely to cause human illness, disorders or disability.
Public Sewer System: Any sewer that is controlled by a public entity or will be turned over to a public entity upon completion.
Public Waters: Lakes, bays, ponds, impounding reservoirs, springs, wells, rivers, streams, creeks, marshes, inlets, canals, and all other bodies of surface or underground waters, natural or artificial, public or private, which are wholly or partially within or bordering the County of El Dorado or within its jurisdiction.
Replacement Area (Repair Area): An area that is one hundred (100) percent in size of the area approved for the initial sewage system disposal field for a residence, and three hundred (300) percent in size of the area approved for the initial sewage system disposal field for others.
Repair (System Repair): Installation, replacement and/or connection of the portion(s) of a system necessary to eliminate a public health hazard or pollution of public waters created by a failing system.
Sand Filter System: A system combining a septic tank or other treatment unit, dosing system with effluent pump(s) and controls, piping and fittings, sand filter and disposal area.
Scum: A mass of organic or inorganic materials floating on the surface of sewage.
Septic Tank: A watertight receptacle which receives sewage from a building or structure, that functions to separate solids from liquids, retains and digests organic matter and discharges the resulting effluent to a second treatment unit or to a soil disposal area.
Septic Tank Effluent: Partially treated sewage, which is discharged from a septic tank.
Sewage: Backwater, Gray water, and/or any liquid contaminated with materials thereof
Single Family Dwelling: A dwelling designed for and commonly occupied exclusively by one family.
Slope: The rise or fall in feet per one hundred (100) feet of horizontal distance. Slope is expressed as a percent of grade. For example: a land surface at a 45 degree angle has a slope of 100%.
Soil: The unconsolidated mineral or organic matter on the surface of the earth that has been subjected to and influenced be genetic and environmental factors of, parent material, climate, macro-and-micro-organisms, and topography, all acting over a period of time and producing a product-soil- that differs from the material from which it is derived in many physical, chemical, biological, and morphological properties and characteristics.
Soil Color: Color of moist soil in terms of hue, value, and chroma-for example, 1 OYR 3/2-using a Munsell Soil Color Chart (Kollmorgen Instruments Corp., 1990).
Soil Consistence: The attributes of the soil materials as expressed in its degree of cohesion and adhesion or in its resistance to deformation or rupture. Terms used in describing consistence are: wet soil-non sticky, slightly sticky, sticky, and very sticky; plasticity-non-plastic, slightly plastic, plastic, and very plastic; moist soil-loose, very friable, firm, very firm, and extremely firm; dry soil-loose, soft, slightly hard, hard, very hard, and extremely hard; cementation-weakly cemented, cemented, strongly cemented, and indurate.
Soil Description: A notation of soil properties at the soil test pit including slope, parent rock type, Rock fracturing, effective soil depth, and depth to groundwater, if observed; and, for each horizon observed, a notation of depth, texture, rock fragment content, color, redoxymorphic features, structure, pores, clay films, consistence, plasticity, stickiness, roots, horizon boundary, and moisture content.
Soil Horizon: A layer of soil that is distinguishable from adjacent layers by characteristic physical properties such as structure, color, or texture, or by chemical composition, including content of organic matter or degree of acidity or alkalinity.
Soil Horizon Boundary: The topography and distinctness of the change between two soil horizons. In soil descriptions, the soil horizon boundary is noted as smooth, wavy, irregular or broken. Distinctness of the changes between horizons is noted as abrupt, clear, gradual, or diffuse.
Soil Moisture: The moisture content of the soil at the time the soil description was made. Described as dry, damp, moist, saturated, or seepage.
Soil Plasticity: See Soil Consistence.
Soil Pores: Generally tubular voids o the soil material formed by roots, animals, and other agents. In soil descriptions pores are noted as few, common, or many in quantity, and as fine, medium or course in size.
Soil Rock Fragment: Rock and mineral particles in the soil greater than 2.Omm in diameter. Includes gravel, cobbles, and stones. In soil descriptions noted as percent by volume.
Soil Roots: The abundance and size of roots in a soil horizon. In soil descriptions abundance is noted as none, few, common, or many. Where present, root size is noted as very fine, fine, medium, or course.
Soil Separate: The groups of mineral particles separated on the basis of range of size. The principal separates are sand, silt, and clay.
Soil Stickiness: See Soil Consistence.
Soil Structure: The combination or aggregation of primary soil particles into aggregates or clusters (peds), which are separated from adjoining peds by surface of weakness. Soil structure is classified on the basis of size, shape, and distinctness into classes, types, and grades.
Soil Test Pit: An Excavation of sufficient size and depth to allow thorough examination of the soil to evaluate its suitability for sewage disposal.
Soil Texture: The relative proportion of soil separates in a soil as described by the twelve (12) classes of texture. The major textural classifications are defined as follows;
(a) Sand: Soil material that contains 85% or more of sand; percentage of silt, plus 1.5 times the percentage of clay shall not exceed 15.
(b) Loamy Sand: Soil material that contains at the upper limit 85% to 900~? sand, and the percentage of silt plus 1.5 times the percentage of clay in not less than 15; at the lower limit it contains not less than 70% to 85 % sand, and the percentage of silt plus twice the percentage of clay does not exceed 30.
(c) Sandy Loam: Soil material that contains either 20% clay or less, and the percentage of silt plus twice the percentage of clay exceeds 30, and 52% or more sand; or, less that 7% clay, less than 50% silt and between 43% and 52% sand.
(d) Loam: Soil material that contains 7% to 27% clay, 28% to 50% silt, and less than 52% sand.
(e) Silt Loam: Soil material that contains either at least 50% silt and 12% to 27% clay; or 50% to 80% silt and less than 12% clay.
(f) Silt: Soil material that contains 80% or more silt and less than 12% clay.
(g) Sandy Clay Loam: Soil Material that contains 20% to 35% clay, less than 28% silt, and 45% or more sand.
(h) Clay Loam: Soil material that contains 27% to 40% clay and 20% to 45% sand.
(i) Silty Clay Loam: Soil material that contains 27% to 40% clay and less than 20%
Sandy Clay: Soil material that contains 35% or more clay and 45% or more sand.
(k) Silty Clay: Soil material that contains 40% or more clay and 40% or more silt.
(l) Clay: Soil material that contains 40% or more clay, less than 45% sand, and less than 40% silt.
Soil With Rapid Permeability: Soil with:
(a) percolation rates of five (5), or less, minutes per inch, or
(b) soil texture classes of sand or loamy sand as defined in the Soil Texture definition, or
(c) soils containing more than 50% coarse fragments greater than 2 mm. in diameter.
Special Design System: Any Division of Environmental Health-approved system that is not a standard system, experimental system, vault privy, holding tank, pit privy, kitchen waste disposal system, Gray water system or portable toilet.
Swale: A depression that carries water during or immediately after rainfall.
System: A facility, including replacement area, designed for the treatment and disposal,of sewage, or sewage storage only, on a site.
Standard System: An on-site sewage disposal system consisting of a septic tank, distribution unit and gravity-flow disposal field constructed using a minimum of six (6) inches of filter material below the distribution pipe or gravel-less chambers, and maintaining not less than four (4) feet of effective soil depth below the bottom of the trench. A standard system is designed based on percolation test results of 5 to 3 0 m.p.i. with a minimum of eighteen (18) inches of filter material under the pipe; with percolation test results of 30 to 60 m.p.i. with eighteen (18) inches maximum of filter material under the pipe, maximum 3 feet deep, and includes gravel-less chambers.
Test Pit (test trench, soil mantle): An excavation of sufficient size and depth to allow thorough examination of the soil to evaluate its suitability for sewage disposal.
Toilet Facility: A fixture housed within a toilet room or shelter for the purpose of receiving backwater
Unstable Land forms: Areas that show evidence of down-slope mass movement such as landslides, earthflows, debris flows, or rockfalls.
Vault Privy: A structure for collection of human waste without the aid of water. It consists of a shelter built above a watertight vault in the ground into which human waste falls. The vault privy has no direct water connection.
Vertical Drain: An artificial drain up slope from a disposal field to intercept and divert groundwater by penetrating a limiting layer and draining into underlying permeable soils.
Vertical Separation: The vertical distance between the disposal trench bottom and a limiting layer, fractured bedrock, or groundwater.
Water table: That level of groundwater where the hydraulic pressure is zero.
Waterless Toilet: A composting toilet, incinerating toilet or similar device for the holding and processing of backwater and/or Gray water Not approved for use in El Dorado County.
Wet Weather Testing: Wet weather conditions are defined as when V2of the annual rainfall has occurred for the elevation where the property is being tested.
Wetland: An area that has a predominance of hydric soils and that is inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and under normal circumstances, does support a prevalence of hydrophytic vegetation typically adapted for life in saturated soil conditions.
1. Table 1 - Minimum Setback Distances
2. Table 2 - Sewage Flows According to Type of Establishment
3. Table 3 - Drainage Fixture Unit Values for Varies Plumbing Fixtures
4. Table 4 - Capacity of Septic Tanks
1. Septic tank sizes in this table include sludge storage capacity and the connection of domestic food waste disposal units without further volume increase.
2. Extra Bedroom, 150 gallons each.
3. Extra dwelling units over 10, 250 gallons each.
4. Extra fixture units over 100, 25 gallons per fixture unit.
RECOMMENDED DESIGN CRITERIA - Sewage disposal systems sized using the estimated waste/sewage flow rates should be calculated as follows:
(1) Waste/sewage flow, up to 1500 gal day
Flow x 1.5 = septic tank size
(2) Waste/sewage flow, over 1500 gal/day
Flow x 0.75 + 1125 = septic tank size
5. Table 5 - Pretreatment Unit Sizing
Retention Times -
Commercial kitchen waste:
Dishwasher and/or disposal …………………………………… 2.5 hours
Single service kitchen:
Single serving with disposal …………………………………… 1.5 hours
Lint-silt (laundry) …………………………………………...… 2.0 hours
Storage Factors -
Fully equipped ……………………………………………. 8 hr. operation: 1
16 hr. operation: 2
Commercial kitchen ………………………………………… 24 hr. operation: 3
Single service kitchen ……………………………………............………….. 1.5
Auto washers ……………………………………………………. Self-serve: 1.5
Employee operated: 2
Laundries, Laundromats ………………………………… 1.5 (allows for rock filter)
Diagram 1 - Excessive Drop
Diagram 2 - Capping Fill System
Diagram 3 - Pressurized Distribution System
Diagram 4 - Disposal Trench Risers
Diagram 5 - Serial Distribution
Diagram 6 - Septic Tank Detail
Diagram 7 - Curtain Drain
Diagram 8 - Pipe Fitting Distribution
Diagram 9 - Location Map/Site Evaluation Plan
Diagram 10 - Pre Cast Distribution Box
Diagram 11 - Site Evaluation Field Report Form (Page 1)
Diagram 11 - Page 2
Diagram 12 - Sand Specifications/Sand Filter Mounds