(a) All chemicals used to treat sludge must be compatible with the operation of the sludge processing unit and must not adversely affect any other treatment unit or the receiving waters.
(b) The engineering report must justify appropriate chemicals and feed ranges. A pilot plant study or data from a treatment unit must be used. The organic, metal, and hydraulic loadings at the pilot plant must be within 25% of the design organic, metal, and hydraulic loadings.
(c) Each chemical must be handled, stored, and disposed of according to its safety data sheet.
(d) A liquid chemical storage tank must have:
  (1) a liquid level indicator; and
  (2) an emergency overflow receiving basin or drain capable of retaining any spill.
(e) Powdered activated carbon must be stored in an isolated fireproof area.
(f) A storage or handling area where potentially volatile chemicals are present must have electrical outlets, lights, and motors that meet the National Fire Protection Association 70 National Electrical Code® in effect at the time the storage or handling area was constructed, including explosion prevention requirements.
(g) Systems for transport, transfer, storage, and use of any volatile chemical must prevent volatile chemicals from discharging to the atmosphere.
(h) A wastewater treatment facility must have at least a 30-day supply of each chemical in dry storage conditions, unless the engineering report justifies a reduced amount.
(i) A solution storage tank or direct-feed day tank must have sufficient capacity for operation at the design flow of the wastewater treatment facility.
(j) The procedures for measuring the quantity of each chemical used to prepare each feed solution must be included in the wastewater treatment facility's operation and maintenance manual.
(k) A chemical storage tank, pipe, or other equipment must be compatible with the chemical it is designed to handle.
(l) Chemicals must only be combined in a feed solution. Intermixing of chemicals prior to preparing a feed solution is prohibited.
(m) Concentrated liquid acid must not be stored in an open vessel, and must be pumped in undiluted form from the original container to a point of treatment, to an enclosed acid-resistant day tank, or to an enclosed acid resistant storage tank.
(n) Concentrated liquid acid must be kept in a closed, acid-resistant shipping container or storage unit.
(o) The transfer of a toxic material must be controlled by an actuating device.
(p) A wastewater treatment facility must have one or more of the following control methods to ensure that dust will be minimized during the transfer of a dry chemical:
  (1) a closed conveyor system with vacuum pneumatic equipment;
  (2) a facility for emptying shipping containers in a special enclosure; or
  (3) an exhaust fan and dust filter that uses a hopper or bin under negative pressure to eliminate chemical particles in the air.
(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).
(r) A chemical delivery system must meet the following requirements:
  (1) Structures housing equipment.
    (A) A floor surface must be smooth, slip resistant, impervious, and must have a minimum slope of 1/8 inch per foot.
    (B) An open basin, tank, or conduit must be protected from a chemical spill or accidental drainage.
    (C) An area that houses a chemical delivery system must provide access for servicing, repair, and observation of operations.
  (2) Redundancy. A chemical delivery system must have at least two feeders and must be able to supply the amount of chemicals needed for process reliability throughout the feed range. Chemical delivery equipment must be able to maintain operation at design flow with the largest operational unit out of service.
  (3) Design and Capacity.
    (A) A chemical delivery system must be able to deliver a proportional amount of chemical feed based on the rate of flow.
    (B) A chemical delivery system must not use positive displacement type solution feed pumps to feed chemical slurries, unless the engineering report justifies such use.
    (C) If using potable water, the potable water supply 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.
    (D) A chemical delivery system component must be resistant to the chemical it is designed to apply.
    (E) A dry chemical delivery system must:
      (i) measure the chemical volumetrically or gravimetrically;
      (ii) provide effective mixing and solution of the chemical in a solution pot;
      (iii) provide gravity feed from a solution pot;
      (iv) completely enclose chemicals; and
      (v) prevent emission of dust to the operation room.
  (4) Spill Containment. The chemical delivery equipment must have protective curbing to contain a chemical spill.
  (5) Control Systems.
    (A) All chemical delivery systems must have an automatic control system that is capable of manual control.
    (B) A chemical delivery system must have manual starting equipment.
    (C) A chemical delivery system may be designed with an automatic chemical dose or residual analyzer.
    (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) 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) Chemical Delivery System Protection. A chemical delivery system must have freeze protection and must be accessible for cleaning.
  (8) Water Supply.
    (A) A water supply for chemical mixing may be potable water or reclaimed water.
    (B) A chemical delivery system must protect its water supply from contamination. If using potable water, the potable water supply 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.
    (C) A water supply must have sufficient pressure to ensure dependable operations.
    (D) A water supply must include a means for measuring solution concentrations.
    (E) A water supply design must include sufficient duplicate equipment to ensure process reliability.
    (F) A water supply design may include a booster pump to maintain water pressure.
  (9) Solution Tanks.
    (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.
    (B) A chemical delivery system must have at least two solution tanks.
    (C) The solution tank(s) must provide storage for at least one full day of operation at design flow.
    (D) A solution tank must have a drain and a solution level indicator.
    (E) An intake point for potable water must have an air gap.
    (F) A chemical solution tank must be covered and have an access opening that is curbed and fitted with a tight cover.
    (G) Each subsurface solution tank must:
      (i) be impermeable;
      (ii) be protected against buoyancy;
      (iii) include a means to drain groundwater or other accumulated water away from the tank;
      (iv) include leak detection; and
      (v) allow for containment and remediation of any chemical spill.
    (H) An emergency overflow pipe must:
      (i) be turned downward;
      (ii) have an unobstructed discharge;
      (iii) be clearly visible;
      (iv) drain to a containment area; and
      (v) must not contaminate the wastewater or receiving stream.
  (10) Chemical Application.
    (A) A chemical application system must be efficient and operate safely.
    (B) The chemical application system must prevent backflow or back-siphoning between multiple points of feed through common manifolds.
    (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; amended to be effective December 4, 2015, 40 TexReg 8254