1. (a) Capacity. Based on current acceptable design standards, the total capacity of the public water system's production and treatment facilities must always be greater than its anticipated maximum daily demand.

2. (b) Groundwaters.

   1. (1) Disinfection facilities shall be provided for all groundwater supplies for the purpose of microbiological control and distribution protection and shall be in conformity with applicable disinfection requirements in subsection (e) of this section.

   2. (2) Treatment facilities shall be provided for ground water if the water does not meet the drinking water standards. The facilities provided shall be in conformance with established and proven methods.

      1. (A) Filters provided for turbidity and microbiological quality control shall be preceded by coagulant addition and shall conform to the requirements of subsection (d)(10) of this section. Filtration rates for iron and manganese removal, regardless of the media or type of filter, shall be based on a maximum rate of five gallons per square foot per minute.
      2. (B) The removal of iron and manganese may not be required if it can be demonstrated that these metals can be sequestered so that the discoloration problems they cause do not exist in the distribution system.
      3. (C) All processes involving exposure of the water to atmospheric contamination shall provide for subsequent disinfection of the water ahead of ground storage tanks. Likewise, all exposure of water to atmospheric contamination shall be accomplished in a manner such that insects, birds, and other foreign materials will be excluded from the water. Aerators and all other such openings shall be screened with 16-mesh or finer corrosion resistant screen.
   3. (3) Any proposed change in the extent of water treatment required will be determined on the basis of geological data, well construction features, nearby sources of contamination, and on qualitative and quantitative microbiological and chemical analyses.
   4. (4) Appropriate laboratory facilities shall be provided for controls as well as to check the effectiveness of disinfection or any other treatment processes employed.

3. (c) Springs and other water sources.

   1. (1) Water obtained from springs, infiltration galleries, wells in fissured areas, wells in carbonate rock formations, or wells that do not penetrate an impermeable strata and/or any other source subject to surface or near surface contamination of recent origin shall be evaluated for the provision of treatment facilities. Minimum treatment shall consist of coagulation with direct filtration and adequate disinfection. In all cases, the treatment process must achieve at least a 3-log removal or inactivation of Giardia cysts and a 4-log removal or inactivation of viruses before the water is supplied to any consumer.

      1. (A) Filters provided for turbidity and microbiological quality control shall conform to the requirements of subsection (d)(10) of this section.
      2. (B) All processes involving exposure of the water to atmospheric contamination shall provide for subsequent disinfection of the water ahead of ground storage tanks. Likewise, all exposure of water to atmospheric contamination shall be accomplished in a manner such that insects, birds, and other foreign materials will be excluded from the water. Aerators and all other such openings shall be screened with 16-mesh or finer corrosion resistant screen.
   2. (2) Any proposed change in the extent of water treatment required will be determined on the basis of geological data, well construction features, nearby sources of contamination, and on qualitative and quantitative microbiological and chemical analyses.
   3. (3) Appropriate laboratory facilities shall be provided for controls as well as to check the effectiveness of disinfection or any other treatment processes employed.

4. (d) Surface water.

   1. (1) All water secured from surface sources shall be given complete treatment at a plant which provides facilities for pretreatment disinfection, taste and odor control, continuous coagulation, sedimentation, filtration, covered clearwell storage and terminal disinfection of the water with chlorine or suitable chlorine compounds. In all cases, the treatment process must achieve at least a 3-log removal or inactivation of Giardia cysts and a 4-log removal or inactivation of viruses before the water is supplied to any consumer.

   2. (2) No cross-connection or interconnection shall be permitted to exist in a filtration plant between a conduit carrying filtered or post-chlorinated water and another conduit carrying raw water or water in any prior stage of treatment.

      1. (A) Vacuum breakers must be provided on each hose bibb within the plant facility.
      2. (B) No conduit or basin containing raw water or any water in a prior stage of treatment shall be located directly above, or be permitted to have a single common partition wall with another conduit or basin containing finished water.
      3. (C) Make-up water supply lines to chemical feeder solution mixing chambers shall be provided with an air gap or other acceptable backflow prevention device.
      4. (D) Filters shall be located so that common walls will not exist between them and aerators, mixing and sedimentation basins or clear wells. This rule is not strictly applicable, however, to partitions open to view and readily accessible for inspection and repair.
      5. (E) Filter-to-waste connections, if included, shall be provided with an air gap connection to waste.
   3. (3) All drainage conduits shall be constructed so as to be thoroughly tight against leakage. Return of the decanted water and/or sludge to the raw water shall be adequately controlled so that there will be a minimum of interference with the treatment process. Any discharge of wastewater shall be in accordance with the appropriate statutes and regulations.
   4. (4) Reservoirs for pretreatment and/or selective quality control shall be provided where complete treatment facilities fail to operate satisfactorily at times of maximum turbidities or other abnormal raw water quality conditions exist. Recreational activities at such reservoirs shall be prohibited.
   5. (5) Flow measuring devices shall be provided to measure the raw water supplied to the plant and to measure the treated water discharged from the plant. These devices shall be located to facilitate use and to assist in the determination of chemical dosages, the accumulation of water production data, and the operation of plant facilities.

   6. (6) Chemical storage facilities shall be located so as to help in the handling of bulk chemicals by operators and the transfer of chemicals to day tanks and chemical feeders. Also, the movement of chemicals from storage to feed machines shall be done in a manner that facilitates good housekeeping.

      1. (A) Bulk storage facilities at the plant shall be adequate to store at least one month's supply of chemicals. However, local resupply ability may dictate the requirements for plant inventories.
      2. (B) All chemical bulk and day tanks shall be clearly labeled to indicate the tank's contents.
      3. (C) Dry chemicals shall be stored off the floor in a dry, above ground level room and protected against flooding or wetting from floors, walls, and ceilings.
      4. (D) Day tanks shall be provided to minimize the possibility of severely overfeeding liquid chemicals. Day tanks will not be required if adequate process control instrumentation and procedures are employed to prevent chemical overfeed incidents.

      5. (E) When liquid chemicals are to be used, special precautions must be taken and the following concerns must be addressed both during the plan review and approval process for new facilities and during the operation of existing plants:

         1. (i) issues involving bulk storage tank design such as the materials of construction, capacity, overflow, and containment;
         2. (ii) issues involving transfer pump design including the bulk storage tank design, day tank capacity, type, materials of construction, and controls;
         3. (iii) issues involving the day tanks such as the materials of construction, overflow, containment, capacity, and controls;
         4. (iv) issues involving metering pump design such as the materials of construction, calibration, controls, capacity, and anti-siphon protection; and
         5. (v) issues involving piping and valves including their compatibility with solutions.

   7. (7) Treatment plants shall be provided with efficient devices for measuring and applying chemicals to the water being treated.

      1. (A) Each chemical feeder shall have a standby or reserve unit. Common standby feeders are permissible, but, generally, more than one standby feeder must be provided due to the incompatibility of chemicals or the state in which they are being fed (solid, liquid or gas).
      2. (B) All chemical feed equipment shall be capable of easily adjusting to variations in the flow of water being treated.
      3. (C) Dry chemical feeders shall be in a separate room and be provided with facilities for dust control.
      4. (D) Chemical feeders shall be provided with tanks for chemical dissolution when applicable.
      5. (E) Where practical, the transport of chemical solutions between the feeder and the application point should be accomplished through open channels. If enclosed feed lines must be used, they shall be designed and installed so as to prevent clogging and facilitate cleaning.
      6. (F) Coagulants shall be applied to the water in the mixing basins or chambers so as to permit their complete mixing with the water. Coagulants shall be applied continuously during treatment plant operation.
      7. (G) Chlorine feed units, ammonia feed units, and storage facilities shall be separated by solid, sealed walls.
      8. (H) Chemical application points shall be provided to achieve adequate taste and odor control, corrosion control and disinfection.
      9. (I) Chemicals shall be applied in a manner which will ensure optimal finished water quality.

   8. (8) Flash mixing and flocculation equipment shall be provided. This equipment must be capable of adequate flexibility or adjustment to provide optimum flocculation under varying raw water characteristics and rates of raw water treatment.

      1. (A) Where special types of equipment for rapid mechanical mixing, softening, or sedimentation are proposed, the manufacturer must meet the design criteria in paragraph (9) of this subsection.

      2. (B) Facilities for coagulation and sedimentation must be provided to clarify the water so that the settled water turbidity is low enough to produce a finished water which meets the turbidity limits established by the commission's drinking water standards.

         1. (i) Settled water turbidity of less than five turbidity units is generally required to produce a filtered water turbidity which meets the requirements of the drinking water standards.
         2. (ii) All turbidity measurements must be made in accordance with the method specified in the drinking water standards.
      3. (C) Plants with a design capacity greater than 3.0 million gallons per day must provide at least two sets of flash mixing and flocculation equipment which are designed to operate in parallel.
      4. (D) Coagulated water or water from flocculators shall be transported to sedimentation basins in such a manner as to prevent destruction of floc. Piping, flumes and troughs shall be designed to provide a flow velocity of 0.5 to 1.5 feet per second. Gates, ports and valves shall be designed at a maximum flow velocity of four feet per second in the transfer of water between units.

   9. (9) Basins for straight-flow sedimentation of coagulated waters shall provide a theoretical detention time of at least six hours for clarification plants and 4.5 hours for softening plants. The settling chamber of a solids contact clarification unit shall provide a theoretical detention time of at least two hours. Where shorter detention times are desired; engineering data, pilot plant test data, full scale installation data and other information as required by the commission shall be submitted to the executive director for review and approval of the alternate process.

      1. (A) Facilities for sludge removal shall be provided by mechanical means or by the provision of hopper-bottomed basins with valves capable of complete draining of the units. Clarifiers shall be provided with facilities for determining the depth of sludge in the unit.
      2. (B) Basins shall be designed to prevent the short-circuiting of flow or the destruction of floc.
      3. (C) Sedimentation basins may be square, rectangular, round or other shapes approved by the executive director. The length of rectangular settling basins shall preferably be at least twice their width with a side wall water depth of ten feet to 12 feet in nonsoftening water treatment. Square and round sedimentation basins may also be used for clarification and softening plants; however, the detention time must comply with the requirements of this paragraph.
      4. (D) Sedimentation basins shall be provided with facilities for draining the basin within six hours. In the event that the plant site topography is such that gravity draining cannot be realized, a permanently installed electric powered pump station shall be provided to dewater the basin.
      5. (E) Plants with a design capacity greater than 3.0 million gallons per day must provide at least two sedimentation basins or clarification units which are designed to operate in parallel.

   10. (10) Gravity or pressure type filters shall be provided. However, the use of pressure filters shall be limited to installations with a treatment capacity of less than 0.50 million gallons per day.

       1. (A) The depth of filter sand, anthracite or other filtering materials shall be 24 inches or greater. This filtering material shall be free from clay, dirt, organic matter and other impurities. Its effective size shall range from 0.35 to 0.45 mm for fine sand, 0.45 to 0.55 mm for medium sand and 0.55 to 0.65 mm for coarse sand. Its uniformity coefficient shall not exceed 1.7. The grain size distribution shall also be as prescribed by AWWA standards. Material for dual or mixed media filters shall conform to AWWA standards.
       2. (B) Under the filtering material, at least 12 inches of gravel shall be placed varying in size from 1/16 inch to 2.5 inches. The gravel may be arranged in three to five layers such that each layer contains material about twice the size of the material above it. Other support material may be approved on an individual basis.

       3. (C) The filter shall be provided with facilities to regulate the filtration rate and monitor the performance of the filter.

          1. (i) The design of gravity rapid sand filters shall be based on a maximum design filtration rate of two gallons per square foot per minute. At the beginning of filter runs for declining rate filters, a maximum filtration rate of three gallons per square foot per minute is allowed. The filter discharge piping shall be designed with an orifice or other permanently installed flow limiting device to ensure that the maximum filter rate cannot be exceeded.
          2. (ii) Where high-rate dual or multiple media gravity filters are used, a maximum design filtration rate no greater than five gallons per square foot per minute must be used. At the beginning of filter runs for declining rate filters, a maximum filtration rate of 6.5 gallons per square foot per minute is allowed. The filter discharge piping shall be designed with an orifice or other permanently installed limiting device to ensure that the maximum filter rate cannot be exceeded.
          3. (iii) The design of pressure filters shall be based on a maximum filtration rate of two gallons per square foot per minute. When used, the pressure filters shall be installed such that duplicate capacity is available to furnish the design capacity with one filter out of service.
          4. (iv) With the exception of declining rate filters, each filter unit shall be equipped with a manually adjustable rate-of-flow controller with rate-of-flow indication or control valves with indicators.
          5. (v) Each filter unit shall be equipped with a device to indicate loss of head through the filter. In lieu of loss-of-head indicators, declining rate filter units may be equipped with rate-of-flow indicators to monitor filter condition.
          6. (vi) The effluent line of each filter installed after January 1, 1996, must be equipped with a slow opening valve or another means of automatically preventing flow surges when the filter begins operation.
          7. (vii) Filters shall be equipped with sampling taps so that the effluent turbidity of each filter can be individually monitored.

       4. (D) Filters shall be designed to ensure adequate cleaning during the backwash cycle.

          1. (i) Only fully treated water shall be used to backwash the filters. This water may be supplied by elevated wash water tanks or by pumps which take suction from the clearwell and are provided for backwashing filters only. For installations having a treatment capacity no greater than 150,000 gallons per day, water for backwashing may be secured directly from the distribution system if proper controls and rate-of-flow limiters are provided.
          2. (ii) The rate of filter backwashing shall be regulated by rate-of-flow controllers.
          3. (iii) The rate of flow of backwash water shall not be less than 20 inches vertical rise per minute (12.5 gpm/sq. ft.) and usually not more than 30 inches vertical rise per minute (18.7 gpm/sq. ft.). This shall expand the filtering bed 30 to 50%. The freeboard in inches shall exceed the wash rate in inches of vertical rise per minute.
          4. (iv) When used, surface filter wash systems shall be installed with an atmospheric vacuum breaker or a reduced pressure principle backflow preventer in the supply line. If an atmospheric vacuum breaker is used it shall be installed in a section of the supply line through which all the water passes and which is located above the overflow level of the filter.
          5. (v) Gravity filters installed after January 1, 1996, shall be equipped with air scour backwash or surface wash facilities.
   11. (11) Pipe galleries shall be incorporated into the plant design with ample working room, good lighting, and good drainage provided by sloping floors, gutters, and sumps. Adequate ventilation to prevent condensation and to provide humidity control is also required.
   12. (12) The identification of influent, effluent, waste backwash, and chemical feed lines shall be accomplished by the use of labels or various colors of paint. Where labels are used, they shall be placed along the pipe at no greater than five foot intervals. Where colors are used they shall follow the color code prescribed below. Color coding must be by solid color or banding. If bands are used, they shall be placed along the pipe at no greater than five foot intervals. The color code is as follows:
       Attached Graphic
       
   13. (13) An adequately equipped laboratory must be available locally where daily microbiological and chemical tests can be made on water supplied by all plants serving 25,000 persons or more. For plants serving populations of less than 25,000, the facilities for making microbiological tests may be omitted and the required microbiological samples submitted to one of the Texas Department of Health's approved laboratories. All surface water treatment plants shall be provided with equipment for making at least the following determinations: pH, temperature, disinfectant residual, alkalinity, turbidity, "Jar" tests and other tests deemed necessary to monitor specific water quality problems or to evaluate specific water treatment processes. All surface water treatment plants shall provide sampling taps for raw, settled, filtered water and clearwell discharge.

5. (e) Disinfection.

   1. (1) All waters obtained from surface sources must be disinfected prior to storage at a dosage sufficient to produce an adequate residual in the water leaving the plant.
   2. (2) All groundwater must be disinfected prior to distribution. The point of application must be ahead of the water storage tank(s) if storage is provided prior to distribution. Permission to use alternate disinfectant application points must be obtained in writing from the commission.
   3. (3) All water stored in treated water storage tanks must contain a disinfectant residual. Disinfection facilities must be provided for all such locations where an adequate disinfectant residual is not maintained from prior treatment.

   4. (4) Disinfection equipment shall be selected and installed so that continuous and effective disinfection can be secured under all conditions.

      1. (A) Disinfection equipment shall have a capacity at least 50% greater than the highest expected dosage to be applied at any time. It shall be capable of satisfactory operation under every prevailing hydraulic condition.
      2. (B) Automatic proportioning of the disinfectant dosage to the flow rate of the water being treated shall be provided at larger plants and at all plants where the rate of flow varies more than 50% above or below the average flow. Manual control shall be permissible only when the rate of flow is relatively constant or an attendant is always on hand to promptly make adjustments.
      3. (C) All disinfecting equipment on surface water treatment plants shall include at least one standby unit of each capacity for ensuring uninterrupted operation.
      4. (D) Facilities shall be provided for determining the amount of disinfectant used daily as well as the amount of disinfectant remaining for use.
      5. (E) When used, solutions of calcium hypochlorite shall be prepared in a separate mixing tank and allowed to settle so that only a clear supernatant liquid is transferred to the hypochlorinator container.
      6. (F) Provisions shall be made for both pretreatment disinfection and post-disinfection in all surface water treatment plants. Additional application points shall be installed if they are required to adequately control the quality of the treated water.
      7. (G) The use of disinfectants other than chlorine will be considered on a case-by-case basis under the exception guidelines of §290.39(i) of this title (relating to General Provisions).
   5. (5) A full-face self-contained breathing apparatus or supplied air respirator that meets Occupational Safety and Health Administration (OSHA) standards for construction and operation, and a small bottle of fresh ammonia solution (or approved equal) for testing for chlorine leakage shall be readily accessible outside the chlorinator room when chlorine gas is used.
   6. (6) Housing for gas chlorination equipment and cylinders of chlorine shall be in separate buildings or separate rooms with impervious walls or partitions separating all mechanical and electrical equipment from the chlorine facilities. Housing shall be located above ground level as a measure of safety. Equipment and cylinders may be installed on the outside of the buildings when protected from adverse weather conditions and vandals.
   7. (7) Adequate ventilation which includes both high level and floor level screened vents shall be provided for all enclosures in which gas chlorine is being stored or fed. Enclosures containing more than one open 150 pound cylinder of chlorine shall also provide forced air ventilation which includes screened and louvered floor level and high level vents, a fan which is located at and draws air in through the top vent and discharges to the outside atmosphere through the floor level vent, and a fan switch located outside the enclosure. Systems may install negative pressure ventilation in lieu of the above as long as the facilities also have gas containment and treatment as prescribed by the current Uniform Fire Code (UFC).
   8. (8) Hypochlorination solution containers and pumps must be housed and locked to protect them from adverse weather conditions and vandalism. The solution container top must be completely covered to prevent the entrance of dust, insects, and other contaminants.
   9. (9) Safety equipment and training programs for all chemicals used in water treatment shall meet applicable standards established by the Occupational Safety and Health Administration (OSHA) or the Texas Hazard Communications Act, Health and Safety Code, Chapter 502.
   10. (10) Where anhydrous ammonia feed equipment is utilized, it must be housed in a separate enclosure equipped with both high and low level ventilation to the outside atmosphere. The enclosure must be provided with forced air ventilation which includes screened and louvered floor level and high level vents, a fan which is located at and draws air in through the floor vent and discharges through the top vent, and a fan switch located outside the enclosure. Systems may install negative pressure ventilation in lieu of the above as long as the facilities also have gas containment and treatment as prescribed by the current Uniform Fire Code (UFC).
   11. (11) Emergency evacuation procedures must be established where one ton or larger chlorine or anhydrous ammonia cylinders are located within 1/4 mile of residential or other high density developments.
6. (f) Other treatment processes. The adjustment of fluoride ion content, special treatment for iron and manganese reduction, special methods for taste and odor control, demineralization, and other proposals covering other treatment processes will be considered on an individual basis, pursuant to §290.39(g) of this title (relating to General Provisions). Package-type treatment systems and their components shall be subject to all applicable design criteria in this section. Where innovative/alternate treatment systems are proposed, the licensed professional engineer must provide pilot test data, data collected at similar full-scale operations, and proof of a one year manufacturers performance warrantee/guarantee assuring that the plant will produce an effluent of 0.5 NTU or less in at least 95% of the measurements taken each month. Pilot test data must be representative of the actual operating conditions which can be expected over the course of the year.
7. (g) Sanitary facilities for water works installations. Toilet and handwashing facilities provided in accordance with established standards of good public health engineering practices shall be available at all installations requiring frequent visits by operating personnel.
8. (h) Permits for waste discharges. Permits for discharging wastes from water treatment processes shall be obtained from the commission.
9. (i) Treatment chemicals and media. All chemicals and any additional or replacement process media used in treatment of water supplied by public water systems must conform to American National Standards Institute/National Sanitation Foundation (ANSI/NSF) Standard 60 for direct additives and ANSI/NSF Standard 61 for indirect additives. Conformance with these standards must be obtained by certification of the product by an organization accredited by ANSI.
10. (j) Plant operations manual. A thorough plant operations manual must be compiled and kept up to date for operator review and reference. This manual should be of sufficient detail to provide the operator with routine maintenance and repair procedures as well as provide telephone numbers of water system personnel, system officials, and local/state/federal agencies to be contacted in the event of an emergency.

Source Note:The provisions of this §290.42 adopted to be effective October 1, 1992, 17 TexReg 6455; amended to be effective November 3, 1995, 20 TexReg 8620; amended to be effective March 3, 1997, 22 TexReg 1809; amended to be effective February 4, 1999, 24 TexReg 731.