Wyoming Administrative Code › Agency 020 - Environmental Quality, Dept. of › Sub-Agency 0011 - Water Quality › Chapter 11 - DESIGN AND CONSTRUCTION STANDARDS FOR SEWERAGE SYSTEMS, TREATMENT WORKS, DISPOSAL SYSTEMS OR OTHER FACILITIES CAPABLE OF CAUSING OR CONTRIBUTING TO POLLUTION AND MOBILE HOME PARK AND CAMPGROUND SEWERAGE AND PUBLIC WATER SUPPLY DISTRIBUTION SYSTEMS › Part B - MUNICIPAL AND DOMESTIC SEWERAGE SYSTEMS, TREATMENT WORKS, AND DISPOSAL SYSTEM › Section 11-21 - Disinfection

Current through July 13, 2024
(a)
				  Chlorination/dechlorination.
(i) Chlorination.
				  The disinfection capacity shall be sized to provide the coliform concentrations
				  required by the discharge permit. Feeders shall be sized to provide the minimum
				  dosage at the minimum flow rate and to the maximum dosage at the maximum flow
				  rate.
(ii) Dechlorination.
				  Dechlorination feeders shall be sized for the final effluent dechlorination
				  dosage required by the discharge permit requirements.
(iii) Chlorination.
(A) Number of units. Feeders shall be able to
				  supply, at all times, the necessary amounts of chemical at an accurate rate
				  (±3%) throughout the range of feed. The number of units shall provide
				  capacity for effluent disinfection with the largest unit out of service and a
				  separate feeder or feeders for ancillary uses, such as prechlorination or
				  intermediate process control chlorination. The number of feeders shall be
				  selected to permit feeding chemicals over the range of required dosage while
				  only varying a single feeder over a 10:1 range.
(B) Chemical storage. Chlorine shall be
				  stored in a heated, ventilated space. Space shall provide at least thirty (30)
				  days of chemical supply, convenient and efficient handling, and dry conditions.
				  Cylinders or other containers of chlorine gas should be isolated from operating
				  areas and restrained in position to prevent upset.
(C) Piping. Piping systems carrying gaseous
				  or liquid chlorine shall be schedule 80 black steel pipe with forged steel
				  fittings. Bushings shall not be used. Vacuum piping for gaseous chlorine may be
				  polyethylene tubing.
Gas piping between the chlorine pressure reducing valve of
					 the chlorinator and the ejector shall be PVC or polyethylene. Piping for
					 aqueous solutions of chlorine beyond the ejector shall be PVC, fiberglass, or
					 steel pipe lined with PVC or saran.
(D) Maximum withdrawal. The maximum
				  withdrawal rate of gaseous chlorine shall be limited to 40 lbs/day (18.1
				  kg/day) for 100 or 150 lb (45.4 or 68.0 kg) cylinders and 400 lbs/day (181
				  kg/day) for 2,000 lb (907 kg) cylinders, unless chlorine evaporators are
				  used.
(iv)
				  Dechlorination.
(A) Number of units.
				  Dechlorination equipment shall be provided to permit feeding the design dosage
				  with the largest unit out of service. Feeders shall be sized for a 10:1 feed
				  range.
(B) Chemical storage.
				  Chemical storage shall be in a heated, ventilated room, separate from chlorine
				  cylinder storage. Provisions for heating the storage area or the S0 cylinders
				  shall be provided. Where used, bin storage shall be provided with desiccated
				  vents.
(C) Piping. Piping for
				  liquid or gaseous S0 shall be schedule 80 black steel pipe with forged steel
				  fittings. Bushings shall not be used. Piping for aqueous solutions of
				  dechlorination chemicals shall be PVC, fiber glass, or steel pipe lined with
				  PVC or saran. All valves for liquid and gaseous sulfur dioxide shall be as
				  approved by the Chlorine Institute. Valves for aqueous solution of
				  dechlorination chemicals shall be PVC or saran lined.
(D) Maximum withdrawal.
(I) The maximum withdrawal rate for sulfur
				  dioxide from 2,000 lb (907 kg) cylinders shall be 200 lb (90.7 kg) per day,
				  unless sulfur dioxide evaporators are used.
(v) Makeup water. Water used for dissolving
				  dry chemicals, diluting liquid chemicals or operating chlorine or S0 injectors
				  shall be chlorinated and strained for filtered (65 mesh) final effluent or
				  potable water. Where potable water is used, backflow prevention shall be
				  achieved by (a) a six (6) inch (15.2 cm) air gap between the potable water
				  supply pipe and the maximum water level of a receiving tank; or (b) an approved
				  reduced-pressure-zone backflow preventer.
(vi) Mixing requirements. The feed point for
				  chlorination or dechlorination chemical shall be at a location of high
				  turbulence. At points of critical flow, specially designed static tube mixers
				  or artificial mixing are required.
(vii) Contact basins.
(A) Detention time. The chlorine contact
				  period shall provide a minimum of fifteen (15) minutes contact time at the peak
				  hour design flow. The contact period shall be from the point of chemical
				  injection into the flow to the outfall point or dechlorination feed
				  point.
(B) Baffling. Baffling of
				  the chlorine contact basin shall provide a length-to-width ratio of 5:1 or
				  greater.
(viii)
				  Controls. The minimum control for chlorination-dechlorination facilities shall
				  include manual variation of feed rate and a portable chlorine residual
				  monitor.