For all regulated activities, a technical report must accompany the application for contributing zone plan approval. The report must address the following issues. The site description, controls, maintenance, and inspection requirements for the storm water pollution prevention plan (SWPPP) developed under the Texas Pollutant Discharge Elimination System (TPDES) general permits for storm water discharges may be submitted to fulfill paragraphs (1) - (5) of this section, providing the following requirements are met.     
       (1) The report must contain a location map and the site plan.                (A) The location map must be a legible road map with directions, including mileage, which would enable the executive director to locate the site for inspection.                 (B) The site plan must be drawn at a minimum scale of one inch to 400 feet. The site plan must show:                    (i) the 100-year floodplain boundaries (if applicable);                     (ii) the layout of the development, and existing and finished contours at appropriate, but not greater than ten foot contour intervals; and                     (iii) a drainage plan showing all paths of drainage from the site to surface streams;                     (iv) the drainage patterns and approximate slopes anticipated after major grading activities;                     (v) areas of soil disturbance and areas that will not be disturbed;                     (vi) locations of major structural and nonstructural controls identified in the technical report;                     (vii) locations where stabilization practices are expected to occur;                     (viii) surface waters (including wetlands); and                     (ix) locations where storm water discharges to a surface water.          
       (2) The report must describe the nature of the regulated activity (such as residential, commercial, industrial, or utility), including:                (A) the size of the site in acres;                 (B) the projected population for the site;                 (C) the amount and type of impervious cover expected after construction is complete, such as paved surface or roofing;                 (D) the amount of surface area expected to be occupied by parking lots; and                 (E) other factors that could affect the surface water quality.        
       (3) The report must describe the volume and character of storm water runoff expected to occur. Estimates of storm water runoff quality and quantity should be based on area and type of impervious cover, as described in paragraph (2)(C) of this section. An estimate of the runoff coefficient of the site for both the pre-construction and post-construction conditions should be included in the report.      
       (4) The report must describe any activities or processes that may be a potential source of contamination and must provide the following information:                (A) the intended sequence of major activities that disturb soils for major portions of the site (e.g., grubbing, excavation, grading, utilities, and infrastructure installation);                 (B) estimates of the total area of the site that is expected to be disturbed by excavation, grading, or other activities;                 (C) a site map indicating the following: approximate slopes anticipated after major grading activities; areas of soil disturbance; areas that will not be disturbed; locations of major structural and nonstructural controls identified in the technical report; locations where stabilization practices are expected to occur; surface waters (including wetlands); and locations where storm water discharges to a surface water;                 (D) location and description of any discharge associated with industrial activity other than construction; and                 (E) the name of the receiving water(s) at or near the site that will be disturbed or will receive discharges from disturbed areas of the project.        
       (5) The report must describe the temporary best management practices (BMPs) and measures that will be used during construction. The technical report must clearly describe for each major activity identified in paragraph (4) of this section appropriate control measures and the general timing (or sequence) during the construction process when the measures will be implemented. The SWPPP developed under the TPDES general permits for storm water discharges may be submitted to fulfill this part of the technical report providing the following requirements are met.                (A) BMPs and measures must prevent pollution of surface water or storm water that originates upgradient from the site and flows across the site.                 (B) BMPs and measures must prevent pollution of surface water that originates on-site or flows off the site, including pollution caused by contaminated storm water runoff from the site.                 (C) A plan for the inspection of the temporary BMPs and measures and for their timely inspection, maintenance, repair, and, if necessary, retrofit must be included in the report.                 (D) BMPs and measures must meet the requirements contained in §213.5(b)(4)(D)(i) of this title  (relating to Required Edwards Aquifer Protection Plans, Notification, and Exemptions).                 (E) Temporary sediment pond or basin construction plans and design calculation for a proposed temporary BMP or measure must be prepared by or under the direct supervision of a Texas licensed professional engineer. All construction plans and design information must be signed, sealed, and dated by the Texas licensed professional engineer.                 (F) The construction-phase erosion and sediment controls should be designed to retain sediment on site to the extent practicable.                 (G) All control measures must be properly selected, installed, and maintained in accordance with the manufacturer's specifications and good engineering practices. If periodic inspections by the applicant or the executive director or other information indicates a control has been used inappropriately, or incorrectly, the applicant must replace or modify the control for site situations.                 (H) If sediment escapes the construction site, off-site accumulations of sediment must be removed at a frequency sufficient to minimize off-site impacts (e.g., fugitive sediment in street could be washed into surface streams or sensitive features by the next rain).                 (I) Sediment must be removed from sediment traps or sedimentation ponds when design capacity has been reduced by 50%.                 (J) Litter, construction debris, and construction chemicals exposed to storm water must be prevented from becoming a pollutant source for storm water discharges (e.g., screening outfalls, picked up daily).        
       (6) The report must describe the permanent BMPs and measures that will be used after construction.                (A) BMPs and measures must prevent pollution of surface water or storm water originating on-site or upgradient from the site and flows across the site.                 (B) BMPs and measures must prevent pollution of surface water downgradient of the site, including pollution caused by contaminated storm water runoff from the site.                 (C) BMPs and measures must meet the requirements contained in §213.5(b)(4)(D)(ii) of this title.                    (i) Construction plans and design calculations for the proposed permanent BMPs and measures must be prepared by or under the direct supervision of a Texas licensed professional engineer. All construction plans and design information must be signed, sealed, and dated by the Texas licensed professional engineer.                     (ii) The technical report must contain a plan for the inspection of the permanent BMPs and measures and for their timely inspection, maintenance, repair, and, if necessary, retrofit, if requirements contained in §213.5(b)(4)(D) of this title are not being met. This plan must be prepared by the engineer designing the permanent BMPs and measures and signed by the owner or responsible party.                     (iii) Pilot-scale field testing (including water quality monitoring) may be required for permanent BMPs and measures that are not contained in technical guidance recognized by or prepared by the executive director.                        (I) When pilot-scale field testing of an innovative technology (including water quality monitoring) is required, only one pilot site will be approved.                         (II) No additional approvals will be granted until the pilot study is complete and the applicant demonstrates adequate protection of surface water that enters the recharge zone of the Edwards Aquifer.                         (III) If the innovative technology demonstrates adequate protection, additional units may be approved for use as permanent BMPs and measures on the contributing zone.                         (IV) If the innovative technology demonstrates inadequate protection of surface streams that enter the recharge zone of the Edwards Aquifer, a retrofit of the permanent BMP may be required to achieve compliance with §213.5(b)(4)(D) of this title and no additional units will be approved for use on the contributing zone.            
       (7) The technical report must describe the measures that will be taken to avoid or minimize surface stream contamination, or changes in the way that water enters a stream as a result of construction and development. The measures should address the following:                (A) increased stream flashing;                 (B) the creation of stronger flows and instream velocities; and                 (C) other instream effects caused by the regulated activity that increase erosion that results in water quality degradation.        
       (8) The technical report must describe the method of disposal of wastewater from the site.                (A) If wastewater is to be disposed of by conveyance to a sewage treatment plant for treatment and disposal, the existing or proposed treatment facility must be identified.                 (B) If wastewater is to be disposed of by an on-site sewage facility, the application must be accompanied by a written statement from the appropriate authorized agent, stating that the site is suitable for the use of private sewage facilities and will meet or exceed the requirements for on-site sewage facilities as specified under Chapter 285 of this title (relating to On-Site Sewage Facilities), or identifying those areas that are not suitable.                 (C) If wastewater is to be discharged in the contributing zone, requirements under §213.6(c) of this title (relating to Wastewater Treatment and Disposal Systems) must be satisfied.        
       (9) The technical report must describe the measures that will be used to contain any spill of static hydrocarbons or hazardous substances such as on a roadway or from a pipeline or temporary aboveground storage tank system of 250 gallons or more.                (A) Temporary storage facilities are those used on site for less than one year.                 (B) Temporary aboveground storage tank systems of 250 gallons or more cumulative storage capacity must be located a minimum horizontal distance of 150 feet from the five-year floodplain of any stream drainage.        
       (10) The technical report must indicate the placement of permanent aboveground storage tank facilities. Permanent aboveground storage tank facilities for static hydrocarbons and hazardous substances with cumulative storage capacity of 500 gallons or greater must be constructed, and spills removed using the standards contained in §213.5(e)(1) of this title.      
       (11) Exemption.                (A) Regulated activities exempt from the contributing zone plan application requirements under this section are:                    (i) the installation of underground utilities, including:                        (I) storm and sanitary sewage lines;                         (II) natural gas lines;                         (III) telephone lines;                         (IV) electric lines; and                         (V) water lines; and                       (ii) the installation of underground tanks for the storage of static hydrocarbons and hazardous substances.                   (B) An individual land owner who seeks to construct his/her own single-family residence or associated residential structures on the site is exempt from the contributing zone plan application requirements under this subchapter, provided that the land owner does not exceed 20% impervious cover on the site.                 (C) Temporary erosion and sedimentation controls are required to be installed and maintained for exempted activities on the contributing zone. All temporary erosion and sedimentation controls must meet the requirements contained in paragraph (5) of this section, must be installed prior to construction, must be maintained during construction, and may be removed only when vegetation is established and the construction area is stabilized. This subparagraph does not apply to single-family residences on a site greater than five acres or on a site less than five acres and not a part of a common plan of development or sale with the potential to disturb cumulatively five or more acres.                 (D) The executive director may monitor storm water discharges from these projects to evaluate the adequacy of the temporary erosion and sedimentation control measures. Additional protection will be required if the executive director determines that these controls are inadequate to protect water quality.        
     Source Note:        The provisions of this §213.24 adopted to be effective June 1, 1999, 23 TexReg 10489; amended to be effective September 1, 2005, 30 TexReg 4984