Fla. Admin. Code Ann. R. 62-6.014 - Construction Standards for Drainfield Systems

(1) Distribution box - where distribution boxes are used for distributing sewage from the septic tank or other onsite sewage tank to the drainfield lines, the following requirements must be adhered to:

(a) Distribution boxes must be watertight, constructed of durable materials, have adequate structural strength, and be of sufficient size to accommodate the required number of drainfield lines.

(b) Each drainfield line must be connected individually to the box.

(c) The invert of inlets to the box must be at least 1'' inch above the invert of the outlets. The invert of all outlets must be level with respect to each other.

(d) The distribution box must be built as a separate unit from the septic tank and must be set level on solid ground or in mineral aggregate.

(2) Header pipe - header pipe, when used, must be installed in compliance with the following requirements:

(a) Header pipe must meet one or more of the following requirements:

1. ASTM D-3034-21, Standard Specification for Type PSM Poly (Vinyl Chloride) (PVC) Sewer Pipe and Fittings (2021), herein adopted and incorporated by reference. This standard has been deemed copyright protected and is available from the publisher at ASTM International, P.O. Box C700, West Conshohocken, Pennsylvania 19428-2959, or at publisher's website at www.astm.org/, and is available for inspection as provided in subsection (6) below.

2. ASTM D-2729-21 Standard Specification for Poly (Vinyl Chloride) (PVC) Sewer Pipe and Fittings (2021), herein adopted and incorporated by reference. This standard has been deemed copyright protected and is available from the publisher at ASTM International, P.O. Box C700, West Conshohocken, Pennsylvania 19428-2959, or at publisher's website at www.astm.org/, and is available for inspection as provided in subsection (6) below.

3. AASHTO M252-18 Standard Specification for Corrugated Polyethylene Drainage Pipe (2018), herein adopted and incorporated by reference. This standard has been deemed copyright protected and is available from the publisher at American Association of State Highway and Transportation Officials, 444 North Capitol Street N.W., Suite 249, Washington D.C. 20001, and is available for inspection as provided in subsection (6) below.

4. ASTM F-667/667M-16R21, Standard Specification for 3 through 24 in. Corrugated Polyethylene Pipe and Fittings (2021), herein adopted and incorporated by reference. This standard has been deemed copyright protected and is available from the publisher at ASTM International, P.O. Box C700, West Conshohocken, Pennsylvania 19428-2959, or at publisher's website at www.astm.org/, and is available for inspection as provided in subsection (6) below.

5. ASTM F-810-12R18, Standard Specification for Smoothwall Polyethylene (PE) Pipe for Use in Drainage and Waste Disposal Absorption Fields (2018), herein adopted and incorporated by reference. This standard has been deemed copyright protected and is available from the publisher at ASTM International, P.O. Box C700, West Conshohocken, Pennsylvania 19428-2959, or at publisher's website at www.astm.org/, and is available for inspection as provided in subsection (6) below.

(b) Corrugated or smooth wall fittings (elbows, tees and crosses) shall be acceptable for gravity flow headers. Header pipe interior must be smooth. Header pipe must have a minimum inside diameter of 4'' inches for gravity flow applications. Header pipe must not be perforated.

(c) The header pipe must be laid level with direct, connections to each drainfield line and the septic tank outlet pipe. When installed in a drainfield which uses mineral aggregate, the header pipe must be encased in mineral aggregate, and must be included as part of the drainfield area. Gravity flow header pipes, when installed within the mineral aggregate drainfield, may be non-watertight but must be soil tight. Snap connections are acceptable. On non-mineral aggregate systems, header pipe must be supported by soil. All connections must be such that all joints or fittings are firmly connected to pipes. When a drainfield system is a pumped system, the header pipe and fittings must be smooth-walled and watertight. Where the header pipe is not within the absorption surface area it must not be included in drainfield size calculations, but must be considered part of the system. The header pipe must be designed to distribute effluent as equally as practical to each individual drain line and must be supported so that the header is laid level.

(d) Pipe which connects the septic tank outlet to the header pipe or a distribution box must comply with the strength and material standards for header pipe as specified in this subsection.

(3) Low-Pressure dosing - where the total required area of drainfield is greater than 1, 000 square feet or where the applicant proposes to use low-pressure dosing, an automatic dosing device discharging into a low pressure distribution network consisting of 2'' inch or smaller diameter schedule 40 PVC or equal pipe with 1/2'' inch or smaller diameter drilled holes must be used. All piping must use solvent welded connections or equal throughout to prevent dislocation of connections under pressure. The network must be designed for equal distribution of effluent. For the purposes of this section, equal distribution means that the flow from the least effective hole in the network must deliver no less than 75% of the flow from the most effective hole. The selected pump capacity (as measured in Gallons Per Minute) versus total dynamic head must be indicated on a pump curve and must be shown by calculation to achieve an effluent velocity through the network of at least 2' ft. per second to the first exit hole on each lateral. Each line of the pressure network must individually connect to a pressure manifold and be sealed on their distal ends and must not be looped with other lines regardless of whether the drainfield is a bed or a trench or whether it is in a mound, filled subsurface installation. Plans and equipment specifications for low-pressure dosing systems must be approved by the Department prior to construction or installation.

(a) Where the total drainfield area is greater than 1, 000' square feet but not more than 2, 000' square feet, the applicant may, in lieu of low-pressure dosing, choose to split the drainfield into two drainfields, equal in size, each having no more than 1, 000' square feet, with each drainfield being lift-dosed alternately.

(b) Dosing systems with 2, 000' square feet of drainfield or less must consist of a pump tank that receives the flow from a septic tank or other onsite sewage tank. Two pumps must be required for commercial use where dosing is required due to drainfield size or where gravity flow into the drainfield is not possible, and estimated establishment sewage flows exceed 500 gallons per day. Where more than one pump is used, the pumps must dose alternately. Where dosing is required for a commercial system for flows of 500 gallons or less per day, only one pump is required if the drainfield does not exceed 2, 000' square feet.

(c) Systems having more than 2, 000' square feet of drainfield must have a minimum of two dosing pumps, with each pump serving a proportionate amount of the total required absorption area. The pumps must dose alternately.

(d) The volume dosed between the pump operating levels must be adequate to assure that the entire drain pipe network is filled at least four times each cycle.

(e) When a drainfield is installed in slightly limited soil, operating levels must be adjusted to dose the drainfield a maximum of six times in a 24 hour period. For moderately limited soils the drainfield must be dosed no more than four times in a 24 hour period. More frequent dosing may be allowed with systems designed by engineers licensed in the state of Florida.

(f) The distribution network for drainfields having an absorption area less than 1, 500' square feet must be designed by a Florida licensed professional engineer or a master septic tank contractor. The network for drainfields having an absorption area of 1, 500' square feet or larger must be designed by a Florida licensed professional engineer.

(g) Drip emitter systems must be designed in accordance with subsection 62-6.009(5), F.A.C.

(4) Lift dosing - Where a septic tank or sewage waste receptacle is placed too low to permit gravity flow into a properly designed, constructed and located drainfield, a pump tank with a pump or similar type device must be used to lift the effluent to a properly constructed header pipe or distribution box for effluent distribution by gravity to the drainfield. This provision must apply only to drainfields of 1, 000 square feet or less of total absorption area. Tank size and pumps with effluent level controls and alarms must be set in accordance with the requirements set forth in subsection 62-6.013(9), F.A.C.

(5) Drain trenches and absorption beds - drain trenches and absorption beds are the standard subsurface drainfield systems used for disposing of effluent from septic tanks or other sewage tanks. When used, these systems must be constructed as specified below.

(a) When utilizing the standard drain trench method, the width of the trench at the bottom must not exceed 36'' inches. For trenches of 12'' inches or less, there must be a minimum separation distance of 12'' inches between the sidewalls of adjacent trenches; trenches greater than 12 inches require a minimum 24'' inch separation between the sidewalls of adjacent trenches.

(b) The trench method must be the preferred method. Absorption beds may be used in lieu of the standard drain trench method. An absorption bed consists of an area in which the entire earth content of the required absorption area is removed and replaced with aggregate and distribution pipe or other approved alternative drainfield components. The distance between the centers of distribution lines in standard beds must be a maximum of 36'' inches. The distance between the sidewall of the bed and the center of the outside drain line must be no more than 18 inches, but must not be less than six inches. Where header pipe is used in lieu of a distribution box, the header must extend to within 18 inches of the bed sidewalls. In no case must the bottom surface of an absorption bed exceed a total of 1, 500' square feet. Where two or more beds are used to obtain the necessary absorption area, there must be a minimum 10 foot separation between the sidewalls of adjacent absorption beds. Absorption beds must be designed to achieve the maximum length to width ratio practical.

(c) When installing a drainfield system that uses mineral aggregate, all portions of the header pipe and perforated drain pipe must be installed in aggregate conforming to ASTM C33/C33M-18, Standard Specification for Concrete Aggregates (2018) or lightweight aggregate conforming to ASTM C330/C330M-17a Standard Specification for Lightweight Aggregates for Structural Concrete (2017), herein adopted and incorporated by reference. These standards have been deemed copyright protected and are available from the publisher at ASTM International, P.O. Box C700, West Conshohocken, Pennsylvania 19428-2959, or at publisher's website at www.astm.org/, and are available for inspection as provided in subsection (6) below. Aggregate must meet State of Florida Department of Transportation (FDOT) specifications under Section 901, "Standard Specifications for Road and Bridge Construction, January 2019" herein adopted and incorporated by reference. Copies of this document are available as provided in subsection (6) below and at http://www.flrules.org/Gateway/reference.asp?No=Ref-14369. Aggregate must also meet the following gradation requirements.

Sieve size	2 IN.	1 1/2 IN.	1 IN.	3/4 IN.	1/2 IN.	3/8 IN.	No. 4
Percent passing	90-100	35-100	15-100	0-70	0-50	0-30	0-5

In addition, not more than 3.75% by weight of the aggregate material at the point of use must pass a #200 sieve.

1. Approved materials for drainfield mineral aggregate must be limestone, slag, quartz rock, granite, river gravel, recycled crushed concrete, lightweight aggregate and other equally durable materials.

2. The aggregate must be labeled as drainfield aggregate on the freight bill-of-lading. Effective March 1, 1995, a copy of the freight bill-of-lading must be part of the documentation of aggregate size and quality and records must be available for Department review for a period of two years from the date of purchase. This bill-of-lading must clearly certify that the material meets the requirements for drainfield use.

(d) Mineral aggregate material must have a total depth of at least 12'' inches extending throughout the width of the trench or absorption bed. The distribution pipe must have a minimum of six inches of aggregate under the pipe, but must not exceed 10'' inches under the pipe when the total depth of aggregate is 12'' inches.

(e) The drainfield in place must be protected from infiltration of earth backfill by a barrier of polyester bonded filament. The barrier must be placed on top of the drainfield only. For alternative drainfield systems any required earth backfill barrier must be as specified by the alternative system manufacturer, which must be approved by the Department at the time of the initial alternative drainfield approval.

(f) Providing the requirements of subsections 62-6.006(1), (2) and (6), F.A.C., are met, the maximum depth from the bottom of the drainfield to the finished ground surface must not exceed 30 inches after natural settling. The minimum earth cover over the top of the drainfield, distribution box or header pipe in standard subsurface drainfields must be 6 inches after natural settling.

(g) The inside diameter of the drain pipe used in drainfields must be determined based on the type and design of the proposed absorption system. However, for standard gravity aggregate drainfield systems, inside pipe diameter must not be less than 4 inches. Perforated pipe must have two rows of holes, and a minimum perforated area of 1 1/2'' square inches per linear foot. Perforations must be located not less than 30º or more than 60º from the vertical on either side of the center line of the bottom of the pipe. However, for drainfield systems designed by an engineer, drain pipe perforation area and hole configuration must assure that effluent is distributed as equally as possible throughout the drainfield area. All plastic pipe must conform to the standards of ASTM D-3034-21, Standard Specification for Type PSM Poly (Vinyl Chloride) (PVC) Sewer Pipe and Fittings (2021), incorporated by reference in subparagraph 62-6.014(2)(a) 1., F.A.C. ASTM F 667/667M-16R21, Standard Specification for 3 through 24 in. Corrugated Polyethylene Pipe and Fittings (2021), incorporated in subparagraph 62-6.014(2)(a) 4., F.A.C., or ASTM F-810-12R18, Standard Specification for Smoothwall Polyethylene (PE) Pipe for Use in Drainage and Waste Disposal Absorption Fields as incorporated by reference in subparagraph 62-6.014(2)(a) 5., F.A.C.

(h) Depending on the type of drainfield system being utilized, the drainfield absorption surface must be constructed level or with a downward slope not exceeding one inch per 10' feet. Drain lines must be placed at the same slope as the drainfield absorption surface.

(i) The maximum length of drain lines must not exceed 100' feet for all gravity-fed and lift-dosed drainfields, and where two or more drain lines are used, they must be, as near as practical, the same length. The ends of two or more drain lines in bed and mound systems must be connected to produce a continuous circuit. A continuous circuit arrangement is also recommended but not required for standard drain trench systems. However, when a continuous circuit arrangement is not used, the distal ends of the drain lines must be capped or sealed.

(j) No part of a drainfield must be placed within 18'' inches of the treatment or pump tank.

(k) If lots are encountered whereby a standard drainfield system cannot meet drainfield slope or soil cover requirements, a drop box configuration for sloping lots as per Section 7.2.8.1, Chapter 7, EPA 625/1-80-012, Design Manual for Onsite Wastewater Treatment and Disposal Systems, such section hereby incorporated by reference, may be used at the installer's discretion for drainfield construction.

(6) All materials incorporated herein may be obtained from the Department of Environmental Protection, Onsite Sewage Program at www.floridadep.gov or 2600 Blair Stone Road, MS #3596, Tallahassee, Florida 32399-2400 or Florida Department of State, Florida Administrative Code and Register, R.A. Gray Building, 500 South Bronough Street, Tallahassee, Florida 32399-0250. Reference materials deemed copyright protected are available for inspection at the same address.

Notes

Fla. Admin. Code Ann. R. 62-6.014

Rulemaking Authority 381.0065(3)(a), 381.0065(4)(e) FS. Law Implemented 381.0065 FS.

New 12-22-82, Amended 2-5-85, Formerly 10D-6.56, Amended 3-17-92, 1-3-95, Formerly 10D-6.056, Amended 2-3-98, 3-22-00, 5-24-04, 11-26-06, 6-25-09, 7-16-13, Formerly 64E-6.014, Amended by Florida Register Volume 48, Number 110, June 7, 2022 effective 6/21/2022.

New 12-22-82, Amended 2-5-85, Formerly 10D-6.56, Amended 3-17-92, 1-3-95, Formerly 10D-6.056, Amended 2-3-98, 3-22-00, 5-24-04, 11-26-06, 6-25-09, 7-16-13, Formerly 64E-6.014, Amended 6-21-22.