1. (a) Purpose. The purpose of this section is to describe the control facility design requirements that apply to concentrated animal feeding operation (CAFO) general or individual water quality permits or other authorizations under this subchapter.

2. (b) Well buffers. Except as provided by subsection (c) of this section, the control facility of an animal feeding operation (AFO) shall be separated from a well by ensuring a minimum buffer zone, as described in this subsection. An AFO shall not locate a new retention control structure (RCS) or holding pen within the required well buffer zones:

   1. (1) public drinking water supply wells - 500 feet;
   2. (2) drinking water wells used for private water supply - 150 feet; or
   3. (3) water wells used exclusively for agriculture irrigation - 100 feet.
3. (c) Buffer variance. A CAFO operating under an existing authorization may continue the operation and use of any existing holding pens and RCSs located within the required well buffer zones provided they are in accordance with the recharge feature evaluation and certification required under §321.34(f)(3) of this title (relating to Permit Applications). Documentation supporting variances of the buffer zones that were previously authorized shall be kept on site and made available to agency personnel upon request.
4. (d) 100-year flood plain. All control facilities, including holding pens and RCSs, shall be located outside of the 100-year flood plain unless the facility is protected from inundation and damage that may occur during the flood event.

5. (e) RCS design capacity. The following design requirements apply to any AFO, including any CAFO.

   1. (1) The design of a control facility shall include measures that will be used to minimize entry of uncontaminated runoff into RCSs.
   2. (2) Any AFO constructing a new, or modifying an existing, RCS shall ensure that the design specifications and completed construction specifications are certified by a licensed Texas professional engineer. The failure to obtain the certifications or to maintain records verifying the certifications is a violation of this subchapter.
   3. (3) Except as provided in this subsection, each RCS, at a minimum, shall be designed and constructed in accordance with the technical standards developed by the Natural Resources Conservation Service (NRCS), American Society of Agricultural Engineers, American Society of Civil Engineers, or American Society of Testing Materials that are in effect at the time of construction. Where site-specific variations are warranted, a licensed Texas professional engineer shall document these variations and their appropriateness to the design.
   4. (4) Any existing RCS that has been properly maintained without any modifications and has no apparent structural problems or leakage is considered to be properly designed and constructed to meet the capacity requirements, provided that any required documentation was completed in accordance with the requirements at the time of construction. If no documentation exists, the ability of the RCS to meet the capacity for the design rainfall event must be certified by a licensed Texas professional engineer.

   5. (5) Any RCS documented to have been built in accordance with site-specific NRCS plans and specifications is considered to be in compliance with the design and capacity requirements of this subchapter provided that:

      1. (A) the site-specific conditions are the same as those used by the NRCS to develop the plan (numbers of animals, runoff area, wastes generated, etc.); and
      2. (B) the RCS is operated and maintained in accordance with NRCS requirements.
   6. (6) The production area of a new or expanding AFO shall not be constructed in any stream, river, lake, wetland, or playa, except as provided in §321.41 of this title (relating to Special Requirements for Discharges to a Playa).

   7. (7) The design plan must include documentation of the sources of information, assumptions, and calculations used in determining the appropriate volume capacity of the retention control structures (RCSs). The volume must include design rainfall event runoff and normal operating capacity requirements in accordance with subparagraphs (A) and (B) of this paragraph or design rainfall event runoff and evaporation systems in accordance with subparagraphs (A) and (C) of this paragraph.

      1. (A) Design rainfall event runoff.

         1. (i) New source swine, veal, or poultry (chickens and turkeys) CAFOs. Any swine, veal, or poultry (chickens and turkeys) CAFO subject to the new source performance standards in 40 Code of Federal Regulations §412.46 shall have an RCS designed and constructed to meet or exceed the capacity required to contain the runoff and direct precipitation from the 100-year, 24-hour rainfall event.
         2. (ii) All other AFOs. All other AFOs shall have an RCS designed and constructed to meet or exceed the capacity required to contain the runoff and direct precipitation from the 25-year, 24-hour rainfall event, except as required by §321.42(c) of this title (relating to Requirements Applicable to the Major Sole-Source Impairment Zone).

      2. (B) Design capacity requirements for systems using irrigation.

         1. (i) The RCS shall be designed for the authorized number of animals to include any storage volume required by a hydrologic needs analysis (water balance) that documents that the typical irrigation demands of the proposed crop and irrigated land area will not be exceeded.
         2. (ii) Precipitation inputs to the water balance shall be the average monthly precipitation reported in a National Weather Service current publication.
         3. (iii) The consumptive use requirements of the cropping system shall be developed on a monthly basis, and shall be calculated as a part of the water balance.
         4. (iv) The maximum required storage value calculated by the water balance shall not encroach on the storage volume required under subparagraph (A) of this paragraph.
         5. (v) Wastewater application rates used in the water balance shall not induce uncontrolled runoff or create tailwater that causes a discharge.
         6. (vi) All waste and process-generated wastewater produced during a 21-day or greater period.
         7. (vii) Any other relevant volume needed in the water balance, including any required under the air standard permit in §321.43 of this title (relating to Air Standard Permit for Animal Feeding Operations (AFOs)).

      3. (C) Design requirements for evaporation systems. Evaporation systems shall be designed:

         1. (i) to withstand a ten-year (consecutive) period of maximum recorded monthly rainfall (other than catastrophic). In any month in which a catastrophic rainfall event occurs, the water balance shall replace such an event with not less than the long-term average rainfall for that month as determined by a water balance; and
         2. (ii) to maintain sufficient volume to contain rainfall and rainfall runoff from the rainfall event as required by subparagraph (A) of this paragraph without overflow. The depth for this volume must be at least one vertical foot allocated within the RCS above the volume required in clause (i) of this subparagraph.
6. (f) Dewatering system. An irrigation system or other liquid removal system used by an AFO must be designed to ensure that the system is capable of dewatering the RCSs on a regular schedule.

7. (g) RCS embankment and liner design. A permit or authorization shall identify required design specifications for all RCS.

   1. (1) The design specifications for all new construction and for all structural modifications of existing RCSs must describe standards for the quality of soils used, lift thickness and density at optimum moisture content, procedures and minimum requirements for liner and embankment compaction testing, and spillway construction.
   2. (2) For all new construction and for all structural modifications of existing RCSs, each RCS must have a minimum of two vertical feet of materials equivalent to those used at the time of design and construction between the top of the embankment and the structure's spillway. RCSs without spillways must have a minimum of two vertical feet between the top of the embankment and the required storage capacity, including any additional storage required by an alternative standard.

   3. (3) The operator shall ensure site-specific documentation is prepared that shows that no significant hydrologic connection exists between the contained wastewater and water in the state. Where the operator cannot document that no significant hydrologic connection exists, RCSs must have a liner consistent with the requirements of this subsection.

      1. (A) Documentation must show that there will be no significant leakage from the RCS; or that any leakage from the RCS will not migrate to water in the state. A permit or authorization will require documentation of the lack of hydrologic connection certified by a licensed Texas professional engineer or licensed Texas professional geoscientist and must include information on the hydraulic conductivity tested at the optimum moisture content and thickness of the natural materials underlying and forming the walls of the containment structure up to the wetted perimeter.
      2. (B) If it is claimed that no significant leakage would result from the use of in-situ materials, documentation must be provided that leakage will not migrate to waters in the state. The operator must at a minimum include maps showing groundwater flow paths, or that the leakage enters a confined environment. A permit or authorization will require a written determination by an NRCS engineer, or a licensed Texas professional engineer or a licensed Texas professional geoscientist that a liner is not needed to prevent a significant hydrologic connection between the contained wastewater and waters in the state. This information will be considered documentation that no significant hydrologic connection exists.
      3. (C) Site-specific conditions may be considered in the design and construction of liners. Where no site-specific assessment has been performed demonstrating that there will be no significant leakage from the RCS or that any leakage from the RCS will not migrate to water in the state, a liner must be designed by a licensed Texas professional engineer and documented to have hydraulic conductivities no greater than 1 x 10^-7 centimeters per second (cm/sec), with a thickness of 1.5 feet or greater or its equivalency in other materials. The liner must be constructed in accordance with the design and certified as such by a licensed Texas professional engineer. The operator shall maintain the liner to minimize the percolation of wastewater through the liner.
      4. (D) A permit or authorization shall include provisions whereby the executive director may, upon written notice, require the operator to install a leak detection system or monitoring well(s), based upon a determination that significant potential exists for the contamination of water in the state or drinking water.
      5. (E) Documentation of lack of hydrologic connection, liner, and capacity certifications by a licensed Texas professional engineer or licensed Texas professional geoscientist must be completed for each RCS and kept on site.
8. (h) Manure storage. The AFO operator shall provide manure storage capacity based upon manure and waste production, land availability, and the NRCS Field Office Technical Guide or equivalent standards. When manure is stockpiled, it shall be stored in a well-drained area with no ponding of water, and the top and sides of stockpiles shall be adequately sloped to ensure proper drainage. Runoff from manure storage piles must be retained on site. If the manure areas are not roofed or covered with impermeable material, protected from external rainfall, or bermed to protect from runoff in the case of the design rainfall event, the manure areas must be located within the drainage area of the RCS and accounted for in the design calculations of the RCS.

Source Note:The provisions of this §321.38 adopted to be effective April 1, 1987, 12 TexReg 904; amended to be effective September 18, 1998, 23 TexReg 9354; amended to be effective July 15, 2004, 29 TexReg 6652.