When approved by the Department, alternative systems may, at the discretion of the applicant, be utilized in circumstances where standard subsurface systems are not suitable or where alternative systems are more feasible. Unless otherwise noted, all rules pertaining to siting, construction, and maintenance of standard subsurface systems must apply to alternative systems. In addition, the Department may, using the criteria in subsection 62-6.004(4), F.A.C., require the submission of plans prepared by an engineer licensed in the State of Florida, prior to considering the use of any alternative system.
    (1) Waterless, incinerating or organic waste composting toilets – may be approved for use if found in compliance with standards for Wastewater Recycle/Reuse and Water Conservation Systems as defined by ANSI/NSF International Standard Number 41-2018 “”Non-liquid Saturated Treatment Systems”” (September 2018) or NSF International Protocol P157-2019 “”Incinerating Toilet Systems-Health and Sanitation”” (January 2019) hereby adopted and incorporated by reference, and provided that graywater and any other liquid and solid waste is properly collected and disposed of in accordance with standards established in this chapter. These standards have been deemed copyright protected and are available from the publisher at NSF International, 789 North Dixboro Road Ann Arbor, Michigan 48105, or at publisher’s website at www.nsf.org, and are available for inspection as provided in subsection (11) below. For residences, the required drainfield absorption surface and unobstructed area of the system treating the remaining sewage flow must be reduced by 25% when waterless, incinerating or organic waste composting toilets are used exclusively for all toilet wastes. Solids removed from waterless, incinerating or organic waste composting toilets must be mixed with lime, containerized, and disposed of with the solid waste from the establishment. Liquids discharging from waterless, incinerating or organic waste composting toilets must be plumbed into the onsite system serving the establishment.
    (2) Sanitary pit privy – shall not be permitted except at remote locations where electrical service is unavailable. In no case shall such installations be permitted for permanent residences.
    (3) Mound systems – are used to overcome certain limiting site conditions such as an elevated seasonal high water table, shallow permeable soil overlying slowly permeable soil and shallow permeable soil located over creviced or porous bedrock. Special installation instructions or design techniques to suit a particular site shall, using the criteria in subsection 62-6.004(4), F.A.C., be specified on the construction permit in addition to the following general requirements.
    (a) Site preparation must render the site in compliance with requirements of subsections 62-6.006(1)-(6), F.A.C.
    (b) Prior to the construction of a mound system, the applicant may fill all or a portion of a lot utilizing slightly limited soil.
    (c) The O horizon of original topsoil and vegetation must be removed from beneath the drainfield, shoulder and slope area and the exposed underlying soil plowed or roughened to prevent formation of an impervious barrier between the fill and natural soil. Moderately limited soil material may be used in the construction of mound systems, but shall only be used in the construction of mound slopes and the soil cap. If moderately or severely limited soil is to be replaced beneath the mound, Fl. Admin. Code R. 62-6.008, Table III, footnote 3. shall be followed.
    (d) Where the soil material underlying a mound system is of a similar textural material as that used in system construction, the mound drainfield size shall be based on estimated sewage flows as specified in Fl. Admin. Code R. 62-6.008, Table I and upon the quality of fill material utilized in the mound system. When estimated sewage flows are calculated to be less than 200 gallons per day, specifications for system design shall be based on a minimum flow of 200 gallons per day. Maximum sewage loading rates for soils used in mound construction shall be in compliance with the following:
Fill Material
Maximum Sewage Loading Rate to Mound Drain Trench Bottom Surface in gallons per square foot per day
Maximum Sewage Loading Rate to Mound Absorption Bed Bottom Surface in gallons per square foot per day
Sand; Coarse Sand; and Loamy Coarse Sand
0.80
0.60
Fine Sand;
0.80
0.60
Sandy Loam; Coarse Sandy Loam; and Loamy Sand
0.65
0.40
Fine Sandy Loam; Very Fine Sand; Loamy Fine Sand; and Loamy Very Fine Sand
0.35
0.25
    (e) Where moderately limited soils underlie the mound within 36” inches of the bottom of the drainfield, drainfield sizing shall be based on the most restrictive soil texture existing in the profile to a depth of 36” inches below the bottom of the drainfield, using Table III for soil loading rates.
    (f) There shall be a minimum 4′ feet separation between the shoulder of the fill and the nearest trench or absorption bed sidewall. Where a portion of the mound slope will be placed adjacent to building foundations, pilings or supports for elevated structures, mobile home walls, swimming pool walls, retaining walls, or similar obstructions there shall be a minimum 5′ foot separation between the sidewall of the absorption area and the obstruction. Such obstructions shall impact the slope on no more than 50 percent of the shoulder perimeter. Retaining walls must be designed by a professional engineer licensed in the State of Florida to withstand the lateral earth forces under saturated conditions and to prevent seepage. Where mounds are placed on slopes exceeding 2 percent, the toe of the slope on the downslope side of the mound shall extend an additional 4” inches for each additional 1 percent of slope. To taper the maximum elevation of the mound at the outer perimeter of the shoulder down to the toe of the slope, additional moderately or slightly limited fill shall be placed at a minimum 2′ foot horizontal to 1′ foot vertical grade where mound height does not exceed 36” inches. Mound heights which exceed 36” inches shall have a slope not steeper than 3′ foot horizontal to 1′ foot vertical. The entire mound including slopes, shoulders and the soil cap shall be stabilized with vegetation. Slopes steeper than 5:1 shall be sodded or hydroseeded. Soil caps and unsodded slopes must, at a minimum, be hydroseeded or seeded with grass and a layer of hay or similar cover. Where fill material is present in the amount so as to provide a level surface from the top of the required cover over the system over the area where the slopes would normally be located, no slopes shall be required. For example, if the neighboring lot has been permanently filled to the same level as the applicant’s lot, a five-foot separation from the property line to the system will be required, as opposed to requiring the slope area. Stabilization of a mound shall be the responsibility of the septic tank contractor who constructed the mound system unless the written agreement for system construction clearly states the system owner is responsible. Mound slopes which do not conform to permit requirements shall at a minimum be restored to permit specifications prior to stabilizing. Other synthetic or vegetative covers providing protection from mound erosion equal to or better than sod shall be approved by the Department. Final installation approval shall not be granted until sodding, hydroseeding, seeding and haying or other approved stabilization of the mound has occurred. No portion of the drainfield or shoulder area shall be covered with asphalt or a concrete driveway or be subject to vehicular traffic. Landscaping features such as boulders or trees which obstruct drainfield or fill shoulder area shall not be used. Hydroseeding shall be performed in accordance with the product manufacturer’s instructions and Section 7.5, Permanent Seeding, of the Florida Erosion and Sedimentation Control Inspector’s Manual, July 2008, herein incorporated by reference.
    (g) There shall be a soil cap of slightly or moderately limited soil material over the drainfield and shoulder area. The soil cap shall be no less than 6” inches thick at the outer perimeter of the shoulder. Additional soil cap material shall be placed over the mound and graded to provide drainage off and away from the mound. The maximum depth from the bottom of the drainfield to the finished ground surface shall not exceed 30 inches after natural settling.
    (h) The site shall be landscaped according to permit specifications and shall be protected from automotive traffic or other activity that could damage the system. Swales or other surface drainage structures shall be utilized to prevent water shed from mounds draining onto neighboring property.
    (i) All fill material used in the construction of systems shall be free of extraneous non-soil material such as grass, roots and any other debris. Shell fragments less than 2.0 mm in diameter are excluded from the classification of extraneous non-soil materials and are considered to be soil particles. Severely limited soil material shall not be used in system construction. Fill material consisting of mechanically crushed and sieved rock shall not be used in system construction.
    (j) Where moderately limited soil is used to construct a mound system, a low pressure distribution network is required.
    (4) Filled systems – filled systems shall be constructed in accordance with the minimum requirements for mounds, except as provided for in footnote 5., Table III, and that sewage loading rates to trench or absorption bed bottom areas shall be based on values found in Table III.
    (5) Drip irrigation systems – Drip irrigation systems may, at the option of the applicant, be used in lieu of a mineral aggregate drainfield. Drip irrigation systems must meet all requirements of this chapter except as noted below.
    (a) Drip irrigation systems must receive effluent from an approved aerobic treatment unit or a performance-based treatment system designed to meet at least secondary treatment standards for CBOD5 and TSS, and must meet the following requirements:
    1. Drip irrigation systems shall be designed by an engineer licensed in the State of Florida.
    2. The infiltrative area required shall be the same as the area required for a mineral aggregate drainfield with reductions allowed for the reduction of CBOD5 and TSS as noted in this chapter for aerobic treatment units.
    3. In an absorption bed configuration, the drainfield area shall be calculated as extending one foot beyond the sides of the outermost emitter lines. Notwithstanding the provision of Fl. Admin. Code R. 62-6.014(5)(b), the individual bed size limitation of 1500 square feet does not apply to drip emitter systems.
    4. In a trench containing a single emitter line, the drainfield area shall be calculated as 2′ feet multiplied by the emitter spacing in feet multiplied by the number of emitters.
    5. Drip effluent disposal systems shall be considered pressure distribution systems. Head loss calculations shall be provided to insure proper hydraulic pressure at the emitter. Pump selection shall be indicated in the design specifications. Pump performance curves shall be included in the permit application.
    6. Recirculation rates shall be in the design specifications.
    7. Check valves, petcocks, inline filters, and vacuum breaking device locations shall be shown on the design drawings.
    8. Drip irrigation systems shall be time-dosed over the 24-hour period. Demand control dosing shall override timed-dosing in periods of flow where timed dosing cannot accommodate the excessive flow.
    9. Emitter lines shall be designed as a continuous loop circuit with no dead-ends.
    10. Emitter lines shall be drawn to scale and emitter spacing shall be indicated on the drawings.
    11. Vacuum release valves shall be installed at the highpoint of the emitter lines.
    12. The maximum emitter longitudinal spacing on an emitter line shall be 2′ feet. The maximum spacing between adjacent emitter lines in an absorption bed configuration shall be 2′ feet. The 24”-inch separation from the seasonal high water table shall be measured from the emitter orifice. Setbacks shall be measured from the drip emitter lines.
    13. The setback from drip emitter lines to building foundations and property lines shall be no less than two feet.
    14. The definition of a filled system in Fl. Admin. Code R. 62-6.002, is not applicable to drip effluent disposal systems. A drip effluent disposal system is considered to be a mound system when any part of the bottom surface of any drip emitter line is located at or above the elevation of undisturbed native soil in the drainfield area. A drip effluent disposal system is considered a standard subsurface drainfield system when the entire bottom surface of every drip emitter line is installed below the elevation of undisturbed native soil in the drainfield area.
    15. For mound systems there shall be a minimum 18”-inch separation between the shoulder of the fill and the nearest drip emitter line. Mound system slopes shall be in accordance with Fl. Admin. Code R. 62-6.009(3)(f), except that a minimum 2′ foot separation is required between the nearest drip emitter line and a building foundation, retaining wall, or similar obstruction. Mound systems shall be stabilized in accordance with Fl. Admin. Code R. 62-6.009(3)(f)
    16. For standard subsurface systems, the elevation of any fill covering the drainfield shall extend no less than 18 inches away from all emitter lines before tapering down to natural grade.
    17. Minimum cover on the emitter lines shall be 6” inches for all drip irrigation systems. The maximum cover for all drip irrigation systems shall be no greater than 12” inches.
    18. The system shall include a petcock on the dosing pump discharge line for effluent sampling.
    19. All systems shall incorporate an automatic mechanism for backwashing or flushing the drip lines and filters.
    20. All onsite sewage treatment and disposal systems that include a drip effluent disposal system and aerobic treatment unit or performance-based treatment system shall have a biennial operating permit, a maintenance contract with an approved maintenance entity, and shall be inspected in accordance with the requirements of this chapter.
    21. Drip irrigation systems shall be designed to have a minimum operating pressure at the emitter head of 10 PSI, a maximum operating pressure at the emitter head of 45 PSI, a maximum system operating pressure of 60 PSI, and a maximum discharge rate per emitter of 1.5 gallons per hour.
    22. The hydraulic surge storage requirement of Fl. Admin. Code R. 62-6.028, does not apply to drip irrigation systems.
    23. Drip irrigation systems must only use components approved by the Onsite Sewage Program.
    24. Unobstructed area for drip irrigation systems may be located anywhere on the establishment property that meets the setbacks for unobstructed area and can be accessed via transmission lines, supply lines and return lines installed in accordance with this chapter. The land containing only transmission lines, supply lines and return lines shall not be included in the calculation of unobstructed area.
    25. Supply lines and return lines shall be considered as transmission lines for determining setbacks not specified in this section.
    26. Except for slopes required to meet the stabilization requirements of Fl. Admin. Code R. 62-6.009(3)(f), the area over the drip irrigation drainfield shall be stabilized in the same way or vegetated with plant species specified by the design engineer. The species specified shall not include trees.
    27. For drip emitter lines using non-pressure-compensating emitters, the maximum elevation difference shall be four inches between the highest and the lowest emitter in any individual line segment between the supply and the return line. For drip emitter lines using pressure-compensating emitters, there shall be no more than 18” inches of elevation difference between the highest and lowest emitter in any line. Neither property slope nor drip emitter line slope shall result in the depth of cover over the drip emitter lines to be outside of the range permitted in subFl. Admin. Code R. 62-6.009(5)(a)17.
    28. The minimum effective soil depth below drip emitter lines shall be 42” inches; however, spodic layers greater than 24” inches below the drip emitter lines may remain in place at the discretion of the design engineer.
    (b) Drip irrigation systems shall be monitored during required maintenance visits by visual inspection of the ground surface above the emitter lines for evidence of soil saturation at the ground surface.
    (6) Tire chip aggregate systems – tire chip aggregate may be used as a substitute for mineral aggregate in onsite sewage treatment and disposal system drainfields under the following conditions:
    (a) The tire chips meet the specifications for mineral aggregate found in this chapter: Mixed tire and mineral aggregate shall be approved where each type of aggregate meets its respective standard and the combined mixture meets the gradation requirements in Fl. Admin. Code R. 62-6.014(5)(c)
    (b) Exposed wire protrudes no more than one-half (1/2) inch from 90% of the chips.
    (c) At least 80% of the bead wire has been removed from the tires to be chipped.
    (d) The system receives domestic wastewater only.
    (e) Tire chip aggregate shall not be used where the seasonal high water table is less than 12” inches below the bottom of the drainfield at the wettest season of the year.
    (f) In all other respects tire chip aggregates and mixed tire-mineral aggregates shall be installed with identical site restrictions and construction requirements as approved mineral aggregates.
    (7) In-ground Nitrogen-reducing Biofilters (INRB) – As described in this subsection, are defined as an arrangement of materials installed in layers underneath a drainfield for the purpose of reducing the mean total nitrogen (TN) by acting as a biological filter. INRB layers, also referred to as media layers, may be placed beneath the drainfield provided the resulting system meets all requirements of this chapter except as noted in this subsection. All repairs or modifications to existing INRB systems will be required to meet the standards of this subsection. The target removal effectiveness for mean TN is a minimum of 65% for all INRB.
    (a) Where a liner is used as part of the INRB design, the INRB must be designed by a professional engineer, and must be installed per paragraph (c) or (d) below. For INRBs using liners, the engineer must inspect the liner and Media Layer 2 of the system prior to the Department’s construction inspection. Final system approval will not be granted until the engineer has supplied the following in a report to the Department: liner and Media Layer 2 inspection report; an as-built cross section with elevations; a dimensioned plan view of the installed INRB system; and a statement indicating that the system has been installed in conformance with permitting requirements. The engineer’s liner and Media Layer 2 inspection report satisfy the Media Layer 2 inspection requirements of paragraph (e) below. Where paragraph (c) or (d) does not modify a standard found in paragraph (b), the standard found in paragraph (b) will apply.
    (b) INRB layers must be installed as follows:
    1. The drainfield must be installed centered over sand fill material (Media Layer 1) that is at least 18” inches thick and conforms to the textures and colors in subparagraph 10. below. Media Layer 1 must extend beneath the entire drainfield absorption surface and to a point at least one foot beyond the perimeter of any portion of the drainfield absorption surface.
    2. Below Media Layer 1 there must be a layer of nitrogen-reducing media and fine aggregate mix (Media Layer 2) that is at least 12 inches thick and extends beneath the entire drainfield absorption surface and extends at least 24” inches beyond the perimeter of any portion of the drainfield absorption surface. Media Layer 2 must also extend upward along the boundary of Media Layer 1 to a point four to six inches below the bottom of the drainfield. Media Layer 1 must be centered above Media Layer 2. Media Layer 2 must conform with subparagraphs 8. and 11. below.
    3. The bottom of Media Layer 2 must be at least 6” inches above the wet-season water table.

Figure 1. In-ground Nitrogen-reducing Biofilter media layer system
    4. Media longevity and nutrient reduction may be enhanced by the use of low-pressure distribution. Any Department-approved drainfield effluent distribution method may be used.
    5. The existing soil profile throughout the area of the drainfield and the area where the INRB will be placed must indicate slightly limited soils extending from the existing ground surface to at least 36” inches below existing ground surface in addition to compliance with the effective soil depth requirements of subsection 62-6.006(1), F.A.C., for the installation of the drainfield.
    6. Only drainfield materials approved per Rule 62-6.014 or 62-6.009, F.A.C., can be used.
    7. As measured vertically, no portion of Media Layer 2 can be within 18” inches of the absorption surface of the drainfield.
    8. An example of nitrogen-reducing media is lignocellulosic material such as chips or shavings of lumber, wood mulch, yellow pine sawdust, or 2”-inch to 3”-inch wood chips. All sources of lignocellulosic material must be untreated by preservatives. Lignocellulosic material must be free of extraneous non-woody materials such as plastic, metal, grass, leaves, and any other debris. The nitrogen-reducing media must be demonstrated in Florida-based domestic wastewater studies as innovative systems to be effective at providing a substrate for denitrification.
    9. The nitrogen-reducing media must comply with the provisions of Fl. Admin. Code R. 62-6.0151
    10. Media Layer 1 must consist of fine aggregate having a texture of sand or fine sand but excluding:
    a. Those having color values less than or equal to 4 with chromas less than or equal to 3; or
    b. Those with colors on the gley charts.
    11. Media Layer 2 must be composed of 40-60% nitrogen-reducing media by volume, with the remainder to be fine aggregate and must not be installed when the observed water table at time of construction is at or above the lowest depth of Media Layer 2. The fine aggregate to be mixed with the nitrogen-reducing media must be one or more of the following textures: sand, fine sand, coarse sandy loam, sandy loam, loamy sand, fine sandy loam, very fine sand, loamy fine sand, and loamy very fine sand; and must conform to the colors in subparagraph 10., above. Media Layer 2 must shall be thoroughly mixed while the soil is in a non-plastic state, with the constituents uniformly distributed when installed.
    12. Where the system has a total required drainfield size over 1,500′ square feet, the design engineer must address the potential for mounding of the effluent between the drainfield and the bottom of Media Layer 2 at the estimated sewage flow and will increase the separation between the drainfield and Media Layer 2, to ensure Media Layer 1 maintains no less than 18 inches of unsaturated soil beneath the drainfield. A four-inch diameter observation port in the center of the drainfield must be installed to monitor this parameter. The observation port must be capped and lockable and installed within a protective surface cover. A toilet flange must be securely attached to the bottom of the observation port to prevent the port from being inadvertently raised from its installed position. The observation port, including the flange, must be perforated at the lowest elevation possible to allow accurate measurements. If installed within three feet of the sidewall of a bed or trench, the port must be grouted to prevent effluent from flowing down the outer surface of the port to the media.
    13. Drainfield repair will not necessitate Media Layer 2 replacement provided the media has been in use for less than 10 years or if sampling within the previous 12 months shows denitrification at or above the target level for mean TN removal effectiveness which must be a minimum 65%.
    14. Setback distances to the Media Layers 1 and 2 extending to the absorption surface of the drainfield will be reduced as follows:
    a. Except for building foundations, vertical obstructions and pilings for elevated structures, where the required setback is ≤5 feet, the setback must be reduced to one foot.
    b. Where the required setback is ≥10 feet, the setback must be reduced by five feet.
    c. Setbacks to all other parts of the system must comply with the requirements in this chapter and Florida Statutes § 381.0065
    (c) INRB layers with liner, no underdrain, must be installed in accordance with paragraph (b) above with the following variations:
    1. The system drainfield must be low-pressure dosed unless the professional engineer chooses another method to provide nitrification. Lift-dosing may be used provided the design calculations show that the entire distribution network will be charged with each dose.
    2. Media Layer 2 must be enclosed beneath, and on the lower 6-8” inches of all sides, by an impermeable liner composed of polyvinyl chloride (PVC), high-density polyethylene (HDPE), ethylene propylene diene methylene (EPDM) or other material having a thickness of at least 30 mils and being certified by the manufacturer for a minimum lifetime of 30 years buried in contact with sewage. If a manufacturer will not certify the liner for a minimum of 30 years, the engineer of record must choose a liner based on the manufacturer’s product information regarding resistance to physical and chemical substances to which it will be subject over the thirty-year period. EPA-approved landfill liners may be considered by the engineer of record.
    3. No portion of the liner or Media Layer 2 can be within 18” inches of the absorption surface of the drainfield.
    4. The lowest point of the liner or Media Layer 2 must be no less than 6” inches above the wet-season water table. There must be at least 6” inches of unsaturated slightly limited soil between the bottom of the liner and the wet-season water table.
    5. Media Layers 1 and 2 must extend beneath the entire drainfield absorption surface to a point at least 3.5′ feet beyond the perimeter of any portion of the drainfield absorption surface. For repairs, the 3.5′ feet dimension may be reduced incrementally to not less than 1.0′ feet if necessary, to comply with a setback or if physical room is unavailable. Maintaining the 3.5 feet dimension will have a protection factor of 5 in determining the relative priority of competing factors in the application of Fl. Admin. Code R. 62-6.015, Table V. No part of the liner can be placed within 12” inches of the pump or treatment tank.
    6. Media Layer 1 must comply with subparagraph (b)10. above.
    7. Media Layer 2 must comply with subparagraph (b)11. above, be at least 12” inches thick, and extend beneath the entire area below Media Layer 1.
    8. The Department will not require sampling. Sampling may be required by the professional engineer, municipality or other state agency as necessary to comply with applicable regulatory requirements.
    9. Where the system has a total required drainfield size over 1,500′ square feet, the design engineer must address the potential for mounding of the effluent between the drainfield and the liner at the estimated sewage flow and will increase the separation between the drainfield and Media Layer 2 to ensure Media Layer 1 maintains no less than 18 inches of unsaturated soil beneath the drainfield. A four-inch diameter observation port must be installed in the center of the liner to allow the liquid level of effluent contained within the bottom of the media liner to be monitored. The observation port must be capped and lockable and installed within a protective surface cover. A toilet flange must be securely attached to the bottom of the observation port to prevent the port from being inadvertently raised from its installed position. The observation port, including the flange, must be perforated at the lowest elevation possible to allow accurate measurements. If installed within three feet of the sidewall of a bed or trench, the port must be grouted to prevent effluent from flowing down the outer surface of the port to the media.
    10. The perimeter of the liner, in linear feet, multiplied by the perimeter loading rate must not be less than the estimated daily sewage flow for the system. The most restrictive soil texture between the elevation of the bottom of the drainfield and the elevation six inches below the bottom of the liner throughout the area of the installation and 24” inches beyond the perimeter of the liner will be used to determine the media layer perimeter loading rate.
PERIMETER LOADING RATE
Soil Texture