Source: https://www.tceq.texas.gov/permitting/ossf/ossfsystems.html
Timestamp: 2019-04-24 07:02:02+00:00

Document:
Reference table to determine the type of septic system (OSSF) that is suitable for your property. Brief descriptions of treatment and disposal systems.
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Before an on-site sewage facility (OSSF), or septic system, can be constructed, installed, altered, extended, or repaired, the site must first be evaluated by a licensed site evaluator or a licensed professional engineer. Use the table below to determine which systems are suitable (S=Suitable, U=Unsuitable) for a property based on the results of the site evaluation.
Descriptions of the treatment methods and disposal methods are listed below the table.
1 An absorptive drainfield may be used, if a rock horizon is at least 6 inches above the bottom of the excavation, see §285.33(b)(1).
2If the slope in the drainfield area is greater than 30% or is complex, the area is unsuitable for the disposal method.
3Can only be installed in an area where the slope is less than or equal to 2.0%.
4Can only be installed in an area where the slope is less than 10%.
5Requires disinfection before disposal. A form of pressure distribution shall be used for effluent disposal into fractured or fissured rock.
6Requires vegetation cover and disinfection.
7When no porous media exists, measure from the bottom of the excavation or pipe, whichever is less.
8May require gravel analysis for further suitability analysis—see §285.30(b)(1)(B).
9If OSSF is located within a Flood Hazard, see §285.31(c)(2) for special planning requirements.
All OSSFs require surface drainage controls if slope is less than 2%.
are to be constructed in accordance with §285.32(b)(1).
a standard intermittent sand filter as described in §285.32(b)(2).
must be designed by a professional engineer or professional sanitarian.
can only be installed by an Installer Class II.
For more information regarding the testing and approval of a secondary treatment unit, see §285.32(c).
sand filters not described in §285.32(b)(2).
must be designed by a professional engineer when secondary treatment is required. Professional sanitarian can design when secondary treatment is not required.
For more information regarding nonstandard treatment processes, see §285.32(d).
Return to system selection table.
constructed with perforated pipe and gravel.
installed by an Installer Class I or Installer Class II.
sized and constructed in accordance with §285.33(b)(1).
are constructed with either pipe and gravel, leaching chambers, or gravel-less pipe in either a trench or bed configuration and backfilled with sand.
can be installed by an Installer Class I or Installer Class II.
are sized and constructed in accordance with §285.33(b)(2).
are constructed similar to an unlined E-T bed with the exception of an impervious liner being placed between the excavated surface and the constructed disposal system.
dispose of effluent by use of a pump into small diameter perforated pipe in gravel.
are sized and constructed in accordance with §285.33(b)(3).
are installed similar to an absorptive drainfield, however, the effluent is deposited into bottomless chambers that are linked together with solid walled pipe and are allowed a reduction in the absorptive drainfield sizing formula.
are sized and constructed in accordance with §285.33(c)(2).
are installed similar to an absorptive drainfield, except the effluent in deposited into corrugated pipe with either an eight-inch or ten-inch diameter that is wrapped with geo-textile fabric.
may also be used in E-T systems as a substitute for pipe and gravel.
are sized and constructed in accordance with §285.33(c)(1).
consists of small diameter pressurized lines containing pressure reducing emitters spaced at a maximum of 30 inches.
requires a design to be performed by either a professional engineer or professional sanitarian.
are sized and constructed in accordance with §285.33(c)(3).
dispose of effluent that is pumped, under low pressure, into a solid wall force main and then into perforated distribution pipe in gravel.
require a professional design by a professional engineer or professional sanitarian.
are sized and constructed in accordance with §285.33(d)(1).
is a method that disposes of secondary treated effluent onto the surface of the ground after Maintenance of On-Site Sewage Facilities(Septic Systems).
cannot apply effluent to unseeded bare ground or areas used for growing food, gardens, orchards or crops which may be used for human consumption.
is sized and constructed in accordance with §285.33(d)(2).
are pressurized absorptive drainfields constructed above the native soil surface.
are sized and constructed in accordance with §285.33(d)(3).
are constructed similar to an absorptive drainfield with the exception that a 24 inch thick Class Ib and II soil buffer is placed below and all sides of the drainfield excavation to an elevation equal to the top of the porous media.
are sized and constructed in accordance with §285.33(d)(4).

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