NR 110.23(2)(e)2. 2. A chlorine contact tank shall be provided and shall be sized to provide a detention time of 60 minutes at average design flow or 30 minutes at maximum hour design flow.

NR 110.23(2)(e)3. 3. Chlorine contact tanks shall be baffled to provide a flow channel with a minimum length to width ratio of 40:1.

NR 110.23(2)(e)4. 4. The department may approve contact tanks which do not comply with the requirements of this paragraph. Such facilities, however, shall be field tested to demonstrate that short circuiting of hydraulic flow through the contact chamber does not occur.

NR 110.23(2)(f) (f) Dechlorination.

NR 110.23(2)(f)1. 1. Dechlorination shall be provided in accordance with WPDES permit requirements.

NR 110.23(2)(f)2. 2. Dechlorination chemicals shall be rapidly mixed with the effluent.

NR 110.23(2)(f)3. 3. Sulfur dioxide dechlorination systems shall be designed in the same manner as chlorination systems.

NR 110.23(2)(f)4. 4. Effluent reaeration shall be provided after dechlorination if necessary to insure adequate dissolved oxygen concentration in the receiving stream.

NR 110.23(2)(f)5. 5. Dechlorinated effluent shall be monitored for chlorine residual and dissolved oxygen in accordance with WPDES permit requirements.

NR 110.23(2)(g) (g) Safety equipment.

NR 110.23(2)(g)1. 1. Respiratory air-pack protection equipment, meeting the requirements of the national institute for occupational safety and health (NIOSH) shall be available where chlorine gas is handled, and shall be stored at a convenient location. The equipment may not be stored inside any room in which chlorine is used and stored. The equipment shall use compressed air or oxygen, have at least a 30-minute capacity, and be compatible with the units used by the fire department having jurisdiction over the plant.

NR 110.23(2)(g)2. 2. A plastic bottle of ammonium hydroxide shall be provided for the detection of chlorine leaks.

NR 110.23(2)(g)3. 3. Leak repair kits shall be provided when one ton chlorine cylinders are used.

NR 110.23(3) (3) Ultraviolet disinfection. Provisions shall be made to clean ultraviolet units without loss of disinfection. This shall be accomplished by installing multiple ultraviolet units, by providing ultrasonic cleaners, or by providing an effluent holding tank with a capacity of one hour detention at average design flow.

NR 110.23 History History: Cr. Register, November, 1974, No. 227, eff. 12-1-74; r. and recr. Register, March, 1978, No. 267, eff. 4-1-78; r. and recr. Register, February, 1983, No. 326, eff. 3-1-83; CR 09-123: am. (2) (d) and (e) 2. Register July 2010 No. 655, eff. 8-1-10.

NR 110.24 NR 110.24 Lagoons.

NR 110.24(1) (1) Design report. A design report shall be submitted in accordance with s. NR 110.15 (1).

NR 110.24(2) (2) Basis of design.

NR 110.24(2)(a) (a) Number of cells. A minimum of 2 treatment cells shall be provided for aerated lagoons and stabilization ponds. Where a controlled discharge is required, additional effluent storage cells shall be provided.

NR 110.24(2)(a)1. 1. For aerated lagoons designed to treat domestic wastewater only, the hydraulic detention time of each cell shall be based on the following formula:

Where:

T = detention time, days

E = BOD removal efficiency, percent

K = Reaction coefficient (log base e), days-1

NR 110.24(2)(a)1.a. a. For domestic wastewater K = 0.5 at 20°C.

NR 110.24(2)(a)1.b. b. The reaction coefficient (K) must be adjusted for temperature according to the formula:

KT = K20QT-20

Where: