15A NCAC 18C .0404 WATER TREATMENT FACILITIES
(a) Physical Security and Facility Protection. Treatment equipment and chemicals shall be secured against unauthorized access and shall be protected against the weather as follows:
(1) Structures shall comply with provisions of state and local building codes;
(2) Drainage shall be provided by floor drain, wall drain, or slope to door;
(3) Access to the structure shall be a doorway with minimum dimensions of 36 inches wide and 80 inches high or larger. The doorway shall be large enough to accommodate installation or removal of equipment; and
(4) The structure shall have space to facilitate operation and maintenance of treatment equipment, storage of chemicals, required piping and appurtenances, electrical controls, and laboratory testing.
(b) Mixing and Dispersion of Chemicals. Provisions shall be made for mixing and dispersion of chlorine and other chemicals applied to the water. All facilities treating surface water or ground water influenced by surface water shall comply with the disinfection requirements in Rule .2002 of this Subchapter.
(c) Chemical Feed Machines
(1) Durable chemical feed machines designed for adjustable accurate control of feed rates shall be installed for application of all chemicals necessary for appropriate treatment of the water. Sufficient stand‑by units to assure uninterrupted operation of the treatment processes shall be provided. Continuous chemical application must be protected from electrical circuit interruption which could result in overfeed, underfeed or interrupt the feed of chemicals.
(2) Chemical feed lines from the feeders to the points of application shall be of material sized for the design flow rate, corrosion resistant, easily accessible for cleaning and protected against freezing. Length and the number of bends shall be reduced to a minimum.
(3) Piping and appurtenances shall be constructed of suitable material for the chemical being added and the specific application.
(4) A separate feeder shall be used for each chemical applied.
(d) Disinfection Equipment:
(1) Equipment designed for application of chlorine, or some other approved, equally efficient disinfectant shall be provided. Stand‑by units shall be provided. The plans and specifications shall describe the equipment in detail.
(2) Chlorinators shall be installed in tightly constructed, above ground rooms with mechanical ventilation to the outside air. The capacity of exhaust fans shall be sufficient to discharge all air in the rooms every 30 seconds to 1 minute. The fans or their suction ducts shall be located not more than eight inches above floor level. Provisions for entrance of fresh air shall be made. The point of discharge shall be so located as not to contaminate the air in any building or inhabited areas. Electrical switches for operation of fans shall be located outside the chlorinator rooms. Rooms used for storage of chlorine cylinders shall be designed as described above.
(e) Safety Breathing Apparatus. Self-contained emergency breathing apparatus for operators shall be stored outside rooms where gaseous chlorine is used or stored.
(f) Meters and Gauges. Meters and gauges, including raw and finished water meters, shall be installed to indicate and record water flow entering the treatment plant and water pumped or conducted to the distribution system.
(g) Prevention of Backflow and Back‑Siphonage. Submerged inlets and interconnections whereby non‑potable water, or water of questionable quality, or other liquids may be siphoned or forced into or otherwise allowed to enter the finished water supply shall not be permitted.
(h) Chemical Storage. Separate space for storing at least 30 days supply of chemicals shall be provided. A separate room or partitioned space shall be provided for storage of dry fluoride chemicals or liquid fluoride chemicals in portable containers.
(i) Laboratory. Adequate space, equipment, and supplies shall be provided for daily, routine chemical and bacteriological tests. A layout of laboratory furniture and equipment shall be included in the plans.
(j) Toilet Facilities. Toilet facilities shall be provided for the plant personnel.
(k) Waste Handling and Disposal.
(1) Provisions must be made for disposal of water treatment plant wastes such as clarification sludge, softening sludge, iron-manganese sludge, filter backwash water and brines. Untreated waste shall not be returned to the head of the water treatment plant.
(2) Recycling of supernatant or filtrate from waste treatment facilities treating filter wash water, sedimentation basin sludge or clarifier basin sludge to the head of the water treatment plant may be allowed when the following conditions are met:
(A) The water recycled shall be less than 10 percent by volume of the raw water entering the water treatment plant.
(B) A permit has been issued by the appropriate regulatory authority for discharge of wastes to sanitary sewer, stream, lagoon or spray irrigation.
(C) The raw water does not contain excessive algae, finished water taste and odor problems are not encountered and trihalomethane levels in the distribution system do not exceed allowable levels in Rule .1517 in this Subchapter.
History Note: Authority G.S. 130A‑315; 130A‑317; P.L. 93‑523;
Eff. January 1, 1977;
Readopted Eff. December 5, 1977;
Amended Eff. July 1, 1994.