1. (a) Types of Constructed Wetlands. A constructed wetland may be a free water surface system or subsurface flow system.
2. (b) Natural Wetlands. The use of natural wetlands for wastewater treatment is prohibited.

3. (c) Design.

   1. (1) A constructed wetland must be preceded by primary treatment and may be preceded by secondary treatment.
   2. (2) A primary treatment system must be designed to control odor and algae.
   3. (3) A primary treatment system must produce an effluent quality with no more than 150 milligrams per liter of five-day biochemical oxygen demand to minimize anaerobic conditions and stress on vegetative communities in any subsequent wetland treatment unit.
   4. (4) A treatment facility that use a constructed wetland as the means of complying with a permit effluent limit must be sized and designed to ensure that the permit limitations may be met with any one wetland cell out of service. The report must include water balance calculations and the potential effect of evaporation on the predicted effluent concentrations.

4. (d) Vegetation. A constructed wetland must have a diverse vegetative community of emergent and floating plants to minimize any adverse impact from potential disease, insect pests, or species-specific toxicity. A constructed wetland may have the following flora:

   1. (1) Emergent plants including:

      1. (A) Scirpus spp. (bulrush);
      2. (B) Sagittaria spp. (arrowhead);
      3. (C) Phragmites spp. (reeds);
      4. (D) Juncus spp. (rushes);
      5. (E) Elecharis spp. (spikerush);
      6. (F) Cyperus spp. (sedges);
      7. (G) Typha spp. (cattails);
      8. (H) Caladium spp. (elephant ear); or
      9. (I) various aquatic grass species (e.g., wild rice).

   2. (2) Floating plants including:

      1. (A) Lemna spp. (duckweed);
      2. (B) Hydrocotyle umbellata spp. (water pennywort);
      3. (C) Limnobium spongia spp. (frogbit);
      4. (D) Nymphaea spp. (water lily);
      5. (E) Wolffia spp. (water meal); or
      6. (F) other appropriate emergent plant species.
   3. (3) The vegetation used in a constructed wetland must be suitable for the local growing conditions. The use of indigenous plants is recommended, if the species have been demonstrated effective in a constructed wetland wastewater environment. The report must identify the plants in the design.
   4. (4) Plans for harvesting aquatic plants from waters in the state must be reviewed with the United States Army Corps of Engineers to determine if regulatory coordination is required.
   5. (5) Gathering seed plants from natural wetlands must minimize any impact on the harvested plant community and the natural wetlands.
   6. (6) The use of any harmful or potentially harmful wetland plant or organism is subject to review by the Texas Parks and Wildlife Department, as required by 31 TAC §§57.111 - 57.118 and §§57.251 - 57.258 (relating to Definitions; General Rules; Exceptions; Health Certification of Harmful or Potentially Harmful Exotic Shellfish; Transportation of Harmful or Potentially Harmful Exotic Species; Exotic Species Transport Invoice; Exotic Species Permit: Application Requirements; Exotic Species Permit Issuance; Definitions; General Provisions; Permit Application; Denial; Renewal; Amendment; Reporting and Recordkeeping; and Prohibited Acts, respectively).

5. (e) Maintenance activity must not result in a deterioration of water quality.

   1. (1) All herbicides, insecticides, and fertilizers are prohibited in a constructed wetland.

   2. (2) Floating Material Removal.

      1. (A) A constructed wetland must allow the removal of an algal mat or other floating material prior to the effluent entering the wetlands.
      2. (B) A removal mechanism may be a screen, a submerged adjustable inlet, a baffle, or another suitable method. The removal mechanism must be justified in the report.
      3. (C) The removed floating material must be stored and disposed of in a manner that minimizes odor and complies with the requirements of Chapter 330 of this title (relating to Municipal Solid Waste).
   3. (3) A facility operation and maintenance manual for a facility that has a constructed wetland must include detailed description and schedule for maintaining the constructed wetlands.
6. (f) A wetlands system must be matured and functioning properly before wastewater effluent is processed. The report must include a management and oversight program that specifies construction scheduling, plant species selection, planting practices, and start-up procedures.

7. (g) Liners.

   1. (1) The liner for a wetland system must comply with the requirements of §217.203(c) of this title (relating to Design Criteria for Natural Treatment Facilities).
   2. (2) A minimum 6.0 inch layer of productive topsoil must be placed above a liner to encourage root penetration.

8. (h) Berms.

   1. (1) A berm of a constructed wetland must have side slopes no steeper than 3:1.
   2. (2) The interior side slopes must be lined up to 2.0 feet above the normal water level.

   3. (3) The interior side slopes above the normal operational water level and the exterior side slopes must be finished with:

      1. (A) a minimum 6.0 inch productive topsoil layer and vegetated with grass;
      2. (B) a comparable natural erosion control system; or
      3. (C) a synthetic protection system such as paving.
9. (i) Flood Hazard Analysis. A constructed wetland must be protected from flooding in accordance with the requirements of §217.35 of this title (relating to One Hundred-Year Flood Plain Requirements).
10. (j) Nitrification. A constructed wetland that provides nitrification is an innovative and nonconforming technology and subject to §217.7(b)(2) of this title (relating to Types of Plans and Specification Approvals).
11. (k) Allowed Uses. A constructed wetland may be used as a secondary treatment unit, an advanced secondary treatment unit, or for polishing wastewater effluent, but not for primary treatment.

Source Note:The provisions of this §217.209 adopted to be effective August 28, 2008, 33 TexReg 6843.