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TITLE 30ENVIRONMENTAL QUALITY
PART 1TEXAS COMMISSION ON ENVIRONMENTAL QUALITY
CHAPTER 285ON-SITE SEWAGE FACILITIES
SUBCHAPTER DPLANNING, CONSTRUCTION, AND INSTALLATION STANDARDS FOR OSSFS
RULE §285.33Criteria for Effluent Disposal Systems

    (D) Effluent disinfection. Treated effluent must be disinfected before surface application. The effluent quality in the pump tank must meet the minimum required test results specified in §285.91(4) of this title. All new disinfection equipment shall be listed as approved dispensers or disinfection devices for wastewater systems by National Sanitation Foundation (NSF) International or by an ANSI accredited testing institution under ANSI/NSF Standard 46, or approved by the executive director. After January 1, 2016, all new disinfection equipment shall be listed as disinfection devices for wastewater systems by NSF International or by an ANSI accredited testing institution under ANSI/NSF Standard 46, or approved by the executive director. Installation of disinfection devices on new systems shall be performed by a licensed installer II. Tablet or other dry chlorinators shall use calcium hypochlorite properly labeled for wastewater disinfection. The effectiveness of the disinfection procedure will be established by monitoring either the fecal coliform count or total chlorine residual from representative effluent grab samples as directed in the testing and reporting schedule. The frequency of testing, the type of tests, and the required results are shown in §285.91(4) of this title. Replacement of disinfection devices on existing systems may be considered an emergency repair as described in §285.35 of this title (relating to Emergency Repairs) and shall be performed by either a licensed installer II, a licensed maintenance provider, or a registered maintenance technician.

    (E) Minimum required application area. The minimum surface application area required shall be determined by dividing the daily usage rate (Q), established in §285.91(3) of this title, by the allowable surface application rate (Ri = effective loading rate in gallons per square foot per day) found in §285.90(1) of this title or as approved by the permitting authority.

    (F) Landscaping plan. Applications for surface application disposal systems shall include a landscape plan. The landscape plan shall describe, in detail, the type of vegetation to be maintained in the disposal area. Surface application systems may apply treated and disinfected effluent upon areas with existing vegetation. If any ground within the proposed surface application area does not have vegetation, that bare area shall be seeded or covered with sod before system start-up. The vegetation shall be capable of growth, before system start-up.

    (G) Uniform application of effluent. Distribution pipes, sprinklers, and other application methods or devices must provide uniform distribution of treated effluent. The application rate must be adjusted so that there is no runoff.

      (i) Sprinkler criteria. The maximum inlet pressure for sprinklers shall be 40 pounds per square inch. Low angle nozzles (15 degrees or less in trajectory) shall be used in the sprinklers to keep the spray stream low and reduce aerosols. If the separation distance between the property line and the edge of the surface application area is less than 20 feet, sprinkler operation shall be controlled by commercial irrigation timers set to spray between midnight and 5:00 a.m.

      (ii) Planning criteria. Circular spray patterns may overlap to cover all irrigated area including rectangular shapes. The overlapped area will be counted only once toward the total application area. For large systems, multiple sprinkler heads are preferred to single gun delivery systems.

      (iii) Effluent storage and pumping requirements.

        (I) For systems controlled by a commercial irrigation timer and required to spray between midnight and 5:00 a.m., there shall be at least one day of storage between the alarm-on level and the pump-on level, and a storage volume of one-third the daily flow between the alarm-on level and the inlet to the pump tank.

        (II) For systems not controlled by a commercial irrigation timer, the minimum dosing volume shall be at least one-half the daily flow, and a storage volume of one-third the daily flow between the alarm-on level and the inlet to the pump tank.

        (III) Pump tank construction and installation shall be according to §285.34(b) of this title.

      (iv) Distribution piping. Distribution piping shall be installed below the ground surface and hose bibs shall not be connected to the distribution piping. An unthreaded sampling port shall be provided in the treated effluent line in the pump tank.

      (v) Color coding of distribution system. All new distribution piping, fittings, valve box covers, and sprinkler tops shall be permanently colored purple to identify the system as a reclaimed water system according to Chapter 210 of this title (relating to Use of Reclaimed Water).

  (3) Mound drainfields. A mound drainfield is an absorptive drainfield constructed above the native soil surface. The mound consists of a distribution area installed within fill material placed on the native soil surface. The required area of the fill material is a function of the texture of the native soil surface, the depth of the native soil, basal area sizing considerations, and sideslope requirements. A description of mound construction, as well as construction requirements not addressed in this section can be found in the North Carolina State University Sea Grant College Publication UNC-SG-82-04 (1982).

    (A) A mound drainfield shall only be installed at a site where there is at least one foot of native soil; however, approval for installation on sites with less than one foot of native soil may be granted by the permitting authority on a case-by-case basis.

    (B) Mounds and mound distribution systems must be constructed with the longest dimension parallel to the contour of the site.

    (C) Soil classification, loading rates (R(a)), and wastewater usage rates (Q) shall all be obtained from this chapter.

    (D) The depth of soil material (with less than 30% gravel) between the bottom of the media and a restrictive horizon must be at least 1.5 feet to the restrictive horizon or two feet to groundwater. The soil material includes both the fill and the native soil.

    (E) The distribution area is defined as the interface area between the media containing the distribution piping and the fill material or the native soil, if applicable. The distribution length is the dimension parallel with the contour and equivalent to the length of the distribution media which must also run parallel with the contour. The distribution lines within the distribution media must extend to 12 inches of the end of the distribution media. The distribution width is defined as the distribution area divided by the distribution length.

      (i) The formula A(d) = Q/R(a) shall be used for calculating the minimum required distribution area of the mound where:

Attached Graphic

      (ii) The area credited toward the minimum required distribution area can be determined in either of the following ways.

        (I) If the distribution area consists of a continuous six-inch layer of media over the fill, the credited area is the bottom interface area between the media and soil beneath the media.

        (II) If the distribution area consists of rows of media and distribution piping, the credited area can be calculated using the formulas listed in paragraph (1)(C)(i)(I) or (II) of this subsection depending on the depth of the media.

      (iii) For sites with greater than 2% slopes and solid bedrock, saturated zones, or class IV horizons within two feet of the native soil surface, the length to width ratio of the distribution area must be at least 7:1. For sites with greater than 2% slopes and no solid bedrock, saturated zones, or class IV horizons within two feet of the native soil surface, the length to width ratio of the distribution area must be at least 4:1. No length to width ratio is required on a site with 2% slope or less.

      (iv) Effluent must be pressure dosed into the distribution piping to ensure equal distribution and to control application rates.

      (v) If a continuous layer of media is used, the dosing lines must not be spaced more than three feet apart. If rows of media are used, the rows may be as close as three feet apart, measured edge to edge.

      (vi) The dosing holes must not be greater than three feet apart.

    (F) The basal area is defined as the interface area between the native soil surface and the fill material. The formula A(b) = Q/R(a) must be used for calculating the minimum required basal area of the mound where: A(b) = minimum required basal absorptive area in square feet; Q = design wastewater usage rate in gallons per day; R(a) = application rate of the native soil surface in gallons per square foot per day.

      (i) On sites with greater than 2% slope, the area credited toward the required minimum basal area is computed by multiplying the length of the distribution system by the distance from the upslope edge of the distribution system to the downslope toe of the mound.

Cont'd...

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