Ala. Admin. Code r. 335-7-6-.10

Current through Register Vol. 43, No. 1, October 31, 2024

Section 335-7-6-.10 - Disinfection

(1) A disinfectant application rate must be provided to all filtered water to provide at least a one log Giardia lamblia cyst and a two log virus inactivation. This shall be demonstrated by providing a suitable contact time with a primary disinfectant. The acceptable primary disinfectants are chlorine, chlorine dioxide and Ultraviolet Light (UV). Chlorine is the preferred primary disinfectant. Chloramines may not be used as a primary disinfectant.

(a) Should chlorine be used as the primary disinfectant, a CT of at least 70 must be available or the system must demonstrate that a CT acceptable to the Department corresponding to the water characteristics and detention is available, but the chlorine residual entering the distribution system from each plant shall not be less than the level included on the facility's operating permit or less than 1.0 mg/L at any time.

(b) Approval from the Department must be obtained before using any disinfectant other than chlorine. Duplicate equipment may be required. A minimum CT for the disinfectant shall be provided in accordance with Departmental calculations and EPA guidance.

(c) Systems utilizing a primary disinfectant other than chlorine must add a secondary disinfectant to maintain disinfectant residuals in the distribution system. Acceptable secondary disinfectants are chlorine and/or chloramines. Chlorine is the preferred secondary disinfectant. If chlorine is used as a secondary disinfectant the minimum residual entering the distribution system from each treatment plant shall not be less than 1.0 mg/l at any time. Chloramines may be used as a secondary disinfectant only with written Departmental approval. The minimum chloramines residual entering the distribution system from each plant shall not be less than 2.0 mg/L at any time. Systems utilizing chloramines as a secondary disinfectant must revert to initial lead and copper monitoring as outlined in 335-7-11 for a minimum of three years.

(2) Any system that is proposing to change its primary disinfectant must submit to the department a description of the proposed change, a disinfection profile (graphically) for giardia lamblia and viruses, disinfection benchmark, and an analysis of how the proposed changes will affect the current level of disinfection.

(3) Failure to provide disinfection as required or correct a deficiency within 4 hours of occurrence results in a treatment technique violation requiring public notification within 14 days of occurrence. The Department shall be notified of all such deficiencies and resulting action no later than 48 hours of the occurrence of the deficiency.

(4) Any change to the disinfection practices which may affect the contact time must have prior written Departmental approval.

Author: Edgar K. Hughes

Ala. Admin. Code r. 335-7-6-.10

May 23, 1977. Repealed and Readopted: January 4, 1989; October 31, 1990; effective December 5, 1990. (Rule was renumbered from.09 to.17, as per certification filed December 21, 1998; effective January 25, 1999, with no changes made to the rule.) Amended: Filed May 2, 2000; effective June 6, 2000. Repealed and New Rule: Filed November 7, 2005; effective December 12, 2005.

Statutory Authority:Code of Ala. 1975, §§ 22-23-33, 22-23-49, 22-22A-5, 22-22A-6.