1. (a) Treatment processes--standard.

   1. (1) Septic tanks (gravity flow). The septic tank is attached to wastewater fixtures through a watertight pipe identified as a building "stub out" or "house sewer." The septic tank is connected to the house sewer by an inlet device. Effluent from the septic tank, having undergone primary treatment, flows out of the tank through an outlet device into additional treatment processes or a disposal system. A septic tank, constructed in accordance with this chapter, shall meet the following material, component, construction, and approval requirements:

      1. (A) Tank volumetric capacity. Measured from the bottom of the outlet, the liquid volume of a septic tank shall not be less than established in §285.91(2) of this title (relating to Tables). The liquid depth of the tank shall not be less than 30 inches.
      2. (B) Inlet and outlet devices. The flowline of the inlet device shall be at least three inches higher than the flowline of the outlet device, see §285.90(6) and (7) of this title (relating to Figures). The entry point of the outlet device shall be below the liquid level of the tank at a depth between 25% to 50% of the overall liquid depth of the tank. The inlet and outlet devices shall be "T" branch fittings, constructed baffles or other structures or fittings approved by the executive director. All outlet devices must use a "T" unless a executive director approved fitting is installed on the outlet. All inlet and outlet devices shall be installed water tight to the septic tank walls and be a minimum of three inches in diameter.
      3. (C) Baffles and series tanks. All septic tanks shall be divided into two or three compartments by the use of baffles or by connecting two or more tanks in series. In a baffled tank, the baffle shall be located so that one half to two thirds of the total tank volume is located in the first of two compartments. Two or three tanks may be arranged in series to achieve the required liquid capacity. The first tank in a two tank system shall contain at least one half the required volume. The first tank in a three tank system shall contain at least one third of the total required volume, but no less than 500 gallons. Interconnecting inlet and outlet devices may be installed at the same elevation for multiple tank installations. Baffles shall be constructed the full width and height of the tank with a gap between the top of the baffle and the tank top. The baffle shall have an opening located below the liquid level of the tank at a depth between 25% and 50% of the liquid level. The opening may be a slot or hole and a "T" may be fitted. If a "T" is fitted, the inlet to the fitting shall be at the stated depth in this paragraph. Any metal structures, fittings, or fastenings shall be stainless steel.
      4. (D) Inspection and cleanout ports. All septic tanks shall have an inspection and/or cleanout port located on the tank top, but not directly over, the inlet and outlet devices. These ports may be any configuration with the smallest dimension of the opening not less than 12 inches, but large enough to provide maintenance and equipment removal. Septic tanks buried more than 12 inches below the ground surface shall have risers over the port openings. These risers shall extend from within six inches of the ground surface up to the ground surface and be sealed to the tank and capped.
      5. (E) Septic tank construction materials. The septic tank shall be of sturdy, water-tight construction. Materials used shall be steel-reinforced poured-in-place concrete, steel-reinforced pre-cast concrete, fiberglass, reinforced plastic polyethylene, or other materials approved by the executive director. Metal septic tanks are prohibited. The septic tank shall be structurally designed to resist buckling from internal hydraulic loading and exterior loading caused by earth fill and additional surface loads. Tanks exhibiting obvious deflections, leaks, or structural defects shall not be used. Where concrete tanks are installed, sweating at construction joints is acceptable.
      6. (F) Precast concrete tanks. In addition to the general requirements aforementioned in subparagraph (E) of this paragraph, precast concrete tanks shall conform to requirements in the Materials and Manufacture Section and the Structural Design Requirements Section of American Society for Testing and Materials (ASTM) Designation: C 1227-93, Standard Specification for Precast Concrete Septic Tanks (1993).

      7. (G) Fiberglass and plastic polyethylene tank specifications.

         1. (i) General. The tank shall be fabricated to perform its intended function when installed. The tank shall not be adversely affected by normal vibration, shock, climate conditions, nor typical household chemicals. The tank shall be free of rough or sharp edges that would interfere with installation or service of the tank.
         2. (ii) Watertight integrity. The tank shall be designed and constructed so that all joints, seams, component parts, and fittings prevent the entrance of groundwater and prevent the exit of wastewater, except through designed inlet and outlet openings.
         3. (iii) Structural characteristics. Full or empty tanks shall not collapse or rupture when subjected to earth and hydrostatic pressures.
      8. (H) Special requirements for poured-in-place concrete tanks. Concrete tanks shall be structurally sound and water-tight. The concrete structure shall be designed by a registered professional engineer with relevant experience in the field.
      9. (I) Tank manufacturer specifications. Beginning 180 days after the effective date of these rules, all pre-cast or prefabricated tanks shall be clearly and permanently marked, tagged, or stamped with the manufacturer's name, address, and tank capacity near the level of the outlet so as to be clearly visible. Direction of flow into and out of the tank shall be indicated by arrows or other identification clearly marked at the inlet and outlet.
      10. (J) Installation of tanks. Septic tanks must be installed so as to provide at least 12 inches of drop in elevation from the bottom of the outlet pipe to the bottom of the disposal area. A minimum of four inches of sand, sandy loam, clay loam, or pea gravel free of rock shall be placed under and around all tanks, except poured-in-place concrete tanks. Tank excavations should be left open until such time that they have been inspected by the permitting authority. Tank excavations must be backfilled with sand, sandy loam, clay loam, or pea gravel free of rock. It is acceptable to mound soil over a septic tank, which would normally be exposed, to maintain slope to the drainfield.
      11. (K) Pretreatment (Trash) tanks. The executive director may require the use of a pretreatment tank for use in conjunction with aerobic treatment units. Plastics and other non-digestible sewage can impair or prevent an aerobic unit from functioning properly. Those aerobic treatment units that do not prevent non-digestible sewage from interfering with aeration lines and diffusers may be required by the executive director to use pretreatment tanks for all units installed in the state. All pretreatment tanks shall meet all applicable structural requirements of this subchapter.

   2. (2) Intermittent sand filters.

      1. (A) Overview. An intermittent sand filter (a secondary treatment unit) applies wastewater received from a septic tank (the primary treatment unit) through a coarse porous media layer above a bed of sand by means of pressure distribution. The wastewater moves downward through the course sand media receiving further treatment on the surface of the sand particles. The treated wastewater is collected at the bottom of the sand filter and discharged, via gravity or pressure, to an appropriate disposal method discussed in this subchapter. A typical layout and cross-section of an intermittent sand filter is presented in §285.90(8) of this title (relating to Figures).

      2. (B) Filter Bed.

         1. (i) Sand media specifications. Sand filter media must meet ASTM C-33 specifications as outlined in §285.91(11) of this title (relating to Tables).
         2. (ii) Loading rate. Shall not exceed 1.2 gallons/day/square foot.
         3. (iii) Surface area. Minimum surface area shall be calculated using the formula: Q/1.2=Surface Area (Square Feet), where Q is the wastewater flow in gallons per day.
         4. (iv) Depth (thickness) of sand media. There shall be a minimum of 24 inches of sand media.
         5. (v) Filter bed containment. The filter bed shall be constructed of an impervious lined pit or tank. Acceptable liners specifications are detailed in §285.33(a)(2)(A) of this title (relating to Criteria for Sewage Disposal Systems).
         6. (vi) Underdrains. For gravity discharge of effluent to a drainfield, place a three inch layer of pea gravel over a six inch layer of 0.75 inch gravel containing the underdrain collection pipe. When pumpwells are to be used to pump the effluent from the underdrain to the drainfield, they must be constructed of concrete or plastic sewer pipe. The pumpwell must contain a sufficient number of holes so that effluent can flow from the gravel void space as rapidly as the effluent is pumped out of the pumpwell, refer to §285.90(9) of this title (relating to Figures).

2. (b) Treatment processes--proprietary.

   1. (1) System maintenance. Ongoing maintenance contracts in accordance with the maintenance provisions of §285.7 of this title (relating to Additional Application Requirements for Surface Irrigation Systems) shall be required for all proprietary systems.
   2. (2) Electrical wiring. Electrical wiring for proprietary systems shall be in accordance with §285.34(b)(4) of this title (relating to Other Requirements).
   3. (3) Approval of all proprietary systems. All proprietary treatment and disposal systems shall be approved by the executive director prior to their use in the State. Approval of proprietary systems shall be handled utilizing the procedures found in this section.
   4. (4) Approval of proprietary aerobic treatment systems. All agency approved proprietary aerobic treatment systems will be identified and published in a list of approved systems which may be obtained from the executive director. Only treatment systems which have been tested by and are currently listed by NSF International as Class I systems under NSF Standard 40 (1990) or have been tested and certified as a Class I system in accordance with NSF Standard 40 by an American National Standard Institute (ANSI) or NSF International accredited testing institution shall be considered for approval by the executive director. All agency approved systems at the time of the effective date of this rule shall continue to be listed on the list of approved systems subject to retesting under the requirements of NSF Standard 40 and Certification Policies for Wastewater Treatment Devices (1991). In addition, all proprietary aerobic treatment systems undergoing testing by a certification institution recognized by the executive director at the time of the effective date of this rule shall be considered for inclusion on the list of approved systems notwithstanding the fact that the certification institution does not have NSF or ANSI accreditation. The manufacturers of proprietary treatment systems and the accredited certification institution must comply with all the provisions of NSF International Standard 40 and Certification Policies for Wastewater Treatment Devices (1991).

   5. (5) For systems which NSF International, NSF International or ANSI accredited third party testing institutions will not accept for testing because of system size or type and are not approved systems at the time of the effective date of these rules, the manufacturer shall seek approval in the following manner:

      1. (A) These proprietary systems, components, or materials shall be tested by an independent third party in accordance with this subsection and with the supporting data submitted to the executive director for approval before being marketed for sale in the state.
      2. (B) Testing may be accomplished by allowing a number of the items (usually 20 to 50) to be installed via a temporary authorization in areas typical of the site conditions for which the system would be installed. The temporary authorization may be issued by the executive director and, if issued, shall be specific and pertinent to the proposed proprietary process and shall contain provisions as to how the proprietary process is installed and maintained; the testing protocol for collecting and analyzing samples from the system; the monitoring of equipment, if applicable, and provisions for recording data and data retention necessary to evaluate the performance as well as the effect of the proprietary system on public health, groundwater, and surface waters.
      3. (C) Authorized agents may issue installation permits upon receipt of the temporary authorization. The homeowner must be advised in writing that the system is temporarily approved for testing. System failures, regardless of the material or component, shall be replaced by the manufacturer at the manufacturer's expense. A system installed under §285.32(b)(5) of this title (relating to Criteria for Sewage Treatment Systems) is considered to be the responsibility of the manufacturer until the system has obtained final approval by the executive director in accordance with this section.
      4. (D) Upon completion of the two-year test period, the executive director shall require the certification institution to submit a detailed report on the performance of the system tested. After evaluation of the detailed report, the executive director may issue conditional approval for installations only in areas similar to the area in which the system was tested and for a specified performance and evaluation (monitoring) period, not to exceed an additional five years. The system must be monitored by an entity approved by the executive director. Approval or disapproval of these systems, components or materials will be based on their performance during this five year monitoring period. Failure of one or more of the installed units may be cause for disapproval of the proprietary item. The monitoring method for the units shall be established by the executive director. System failures, regardless of the material or component, shall be replaced by the manufacturer at the manufacturer's expense. The homeowner must be advised in writing that the system is conditionally approved.
      5. (E) Upon successful completion of the monitoring period without failure, systemic or otherwise, the monitoring requirements may be lifted by the executive director and the system deemed suitable for use in conditions similar to areas in which the system was tested and monitored.

3. (c) Treatment processes--non-standard. All OSSFs not described or defined in subsections (a) and (b) of this section will be considered to be non-standard treatment systems. These systems shall be submitted to the permitting authority for review by a registered professional engineer or registered sanitarian in accordance with §285.5(3) of this title (relating to Submittal Requirements for Planning Materials). Upon approval, a permit will be issued by the permitting authority.

   1. (1) Types of systems considered non-standard include, but are not limited to, all forms of the activated sludge process, rotating biological contactors, recirculating sand filters, trickling type filters, submerged rock biological filters, sand filters not described in subsection (a)(2) of this section.
   2. (2) Non-standard systems submitted for review will be analyzed on basic engineering principles and the criteria established in this chapter. These systems will be reviewed as one of a kind, site-specific installations.
   3. (3) Electrical wiring. Electrical wiring for non-standard systems shall be in accordance with §285.34(b)(4) of this title (relating to Other Requirements).

Source Note:The provisions of this §285.32 adopted to be effective February 5, 1997, 22 TexReg 1114.