1. (a) A chemical used to treat sludge must be compatible with the operation of the treatment unit and must have no detrimental effect upon receiving waters.
2. (b) The report must justify appropriate chemicals and feed ranges by including a pilot plant study or data from a treatment unit with characteristics such as organic levels, metal concentrations, and hydraulics that are within 25% of the proposed design.
3. (c) Each chemical must be stored safely.

4. (d) A liquid chemical storage tank must include:

   1. (1) a liquid level indicator; and
   2. (2) an overflow receiving basin or drain capable retaining any spill.
5. (e) Powdered activated carbon must be stored in an isolated fireproof area.
6. (f) A storage or handling area where potentially volatile chemicals or conditions may occur must have electrical outlets, lights, and motors that meet National Electric Code, including explosion prevention requirements.
7. (g) Transport, transfer, storage, and use of any volatile chemical must prevent discharge to the atmosphere.
8. (h) A facility must have at least a 30-day supply of each chemical in dry storage conditions, unless the report justifies a reduced amount.
9. (i) A solution storage tank or direct-feed day tank must have sufficient capacity for operation at the design flow of the facility.
10. (j) The procedures for measuring the quantity of each chemical used to prepare each feed solution must be included in the facility's operation and maintenance manual.
11. (k) The design of a storage tank, pipe, or other equipment must be compatible with the chemical it is designed to handle.
12. (l) Intermixing of chemicals prior to preparing a feed solution is prohibited.
13. (m) Concentrated liquid acid must not be stored in an open vessel, but must be pumped in undiluted form from the original container to a point of treatment, a covered day tank, or a storage tank.
14. (n) Concentrated liquid acid must be kept in a closed, acid-resistant shipping container or storage unit.
15. (o) The transfer of a toxic material must be controlled by a positive actuating device.

16. (p) A facility must be designed with one or more of the following control methods to ensure that a transfer of a dry chemical will minimize dust:

    1. (1) Vacuum pneumatic equipment of a closed conveyor system;
    2. (2) A facility for emptying shipping containers in a special enclosure; or
    3. (3) An exhaust fan and dust filter that put a hopper or bin under negative pressure sufficient to eliminate chemical particles in the air.
17. (q) Disposing of a chemical or an empty chemical container must be done in a manner that minimizes the potential for harmful exposure and in compliance with Chapter 335 of this title (relating to Industrial Solid Waste and Municipal Hazardous Waste).

18. (r) Chemical feed equipment must meet the following requirements:

    1. (1) Structures housing equipment.

       1. (A) A floor surface must be smooth, slip resistant, impervious, and must have a minimum slope of 1/8 inch per foot.
       2. (B) An open basin, tank, or conduit must be protected from a chemical spill or accidental drainage.
       3. (C) An area that houses chemical feed equipment must provide access for servicing, repair, and observation of operations.
    2. (2) Redundancy. A feed system must have at least two feeders and must be able to supply the amount of chemicals needed for process reliability throughout the range of feed. Feed equipment must be able to maintain operation at design flow with the largest operational unit out of service.

    3. (3) Design and Capacity.

       1. (A) A feed system must be able to deliver a proportional amount of chemical feed based on the rate of flow.
       2. (B) A feed system must not use positive displacement type solution feed pumps to feed chemical slurries, unless the report justifies such use.
       3. (C) If using potable water, the water must be protected by at least the equivalent of two backflow preventers, including at least one air gap between a supply pipe and a solution tank.
       4. (D) A feed system component must be resistant to the chemical it is designed to apply.

       5. (E) A dry chemical feed system must:

          1. (i) measure the chemical volumetrically or gravimetrically;
          2. (ii) provide effective mixing and solution of the chemical in a solution pot;
          3. (iii) provide gravity feed from a solution pot;
          4. (iv) completely enclose chemicals; and
          5. (v) prevent emission of dust to the operation room.
    4. (4) Spill Containment. The feed equipment must have protective curbing to contain a chemical spill.

    5. (5) Control Systems.

       1. (A) All feed systems must have an automatic control system that is capable of manual control.
       2. (B) A feed system must have manual starting equipment.
       3. (C) A feed system may be designed with an automatic chemical dose or residual analyzer.
       4. (D) If an automatic chemical dosing or residual analyzer is used, the design must require both recording charts and an alarm for any critical value.
    6. (6) Weighing Scales. A volumetric dry chemical feeder or a non-volumetrically calibrated carboy must have weighing scales that measure in increments of no greater than 0.5% of the load.
    7. (7) Feed System Protection. A feed system must have freeze protection and must be accessible for cleaning.

    8. (8) Water Supply.

       1. (A) A water supply for chemical mixing may be potable water or reclaimed water.
       2. (B) A feed system must protect its water supply from contamination.
       3. (C) A water supply must have sufficient pressure to ensure dependable operations.
       4. (D) A water supply must include a means for measuring solution concentrations.
       5. (E) A water supply design must include sufficient duplicate equipment to ensure process reliability.
       6. (F) A design may include a booster pump to maintain water pressure.

    9. (9) Solution Tanks.

       1. (A) A solution tank must be able to maintain uniform strength of solution consistent with the nature of the chemical solution and must provide continuous agitation.
       2. (B) A feed system must have at least two solution tanks.
       3. (C) The solution tank(s) must provide storage for at least one full day of operation at design flow.
       4. (D) A solution tank must have a drain and a solution level indicator.
       5. (E) An intake point for potable water must have an air gap.
       6. (F) A chemical solution tank must be covered and have an access opening that is curbed and fitted with a tight cover.

       7. (G) Each subsurface solution tank must:

          1. (i) be impermeable;
          2. (ii) be protected against buoyancy;
          3. (iii) include a means to drain groundwater or other accumulated water away from the tank;
          4. (iv) include leak detection; and
          5. (v) allow for containment and remediation of any chemical spill.

       8. (H) An overflow pipe must:

          1. (i) be turned downward;
          2. (ii) have an unobstructed discharge;
          3. (iii) be clearly visible;
          4. (iv) drain to a containment area; and
          5. (v) must not contaminate the wastewater or receiving stream.

    10. (10) Chemical Application.

        1. (A) A chemical application system be efficient and operate safely.
        2. (B) The chemicals application system must prevent backflow or back-siphoning between multiple points of feed through common manifolds.
        3. (C) The application of a pH-affecting chemical to the wastewater must be done before the addition of a coagulant.

Source Note:The provisions of this §217.247 adopted to be effective August 28, 2008, 33 TexReg 6843.