Section 18 AAC 80.635 - Disinfection requirements(a) In addition to complying with the requirements of 40 C.F.R. 141.72(disinfection), adopted by reference in 18 AAC 80.010(a), a community water system, non-transient non-community water system, or transient non-community water system that uses a surface water source or a GWUDISW source must meet the applicable requirements of this section.(b) If the department or the EPA has not determined in writing that filtration is required, (1) the owner of a system that does not provide filtration treatment and that uses a surface water source and is a new system must apply the disinfection treatment requirements of 40 C.F.R. 141.72(a)(3) and (4), adopted by reference in 18 AAC 80.010(a), beginning when the system starts operation after the department issues final approval to operate for the system under 18 AAC 80.210(k);(2) the owner of a system that does not provide filtration treatment and that uses a GWUDISW source must, (A) within six months after the department determines that the goundwater source is under the direct influence of surface water, apply the disinfection treatment requirements of 40 C.F.R. 141.72(a)(3) and (4), adopted by reference in 18 AAC 80.010(a); and(B) within 18 months after the department determines that the groundwater source is under the direct influence of surface water, provide disinfection treatment as described in 40 C.F.R. 141.72(a)(1) and (2), adopted by reference in 18 AAC 80.010(a).(c) For a system that does not provide filtration treatment, the department will allow automatic shutoff of delivery of water to the distribution system under 40 C.F.R. 141.72(a)(2)(ii), adopted by reference in 18 AAC 80.010(a), if(1) the department's evaluation of the system configuration confirms adequate protection against negative pressures in the system;(2) provisions exist for high demand periods including fire flow requirements;(3) the department's evaluation of the system confirms that the system has adequate distribution system storage to maintain positive pressure of at least 20 pounds per square inch for continued water use; and(4) the department finds that automatic shutoff does not cause unreasonable risk to health or interfere with fire protection.(d) For a system that provides filtration treatment, the department will, under 40 C.F.R. 141.72(b)(1), adopted by reference under 18 AAC 80.010(a), assess the effectiveness of the removal or inactivation of Giardia lambliacysts and viruses in accordance with standard sanitary engineering practices and principles. The owner shall provide a minimum of 0.5 log Giardia lambliacyst inactivation to supplement filtration and shall maintain a second treatment barrier for microorganisms.Eff. 10/1/99, Register 151; am 11/9/2006, Register 180; am 4/24/2009, Register 190For guidance regarding standard sanitary engineering practices and principles, as addressed in 18 AAC 80.635(d), see EPA's Guidance Manual for Compliance with the Filtration and Disinfection Requirements for Public Water Systems Using Surface Water Sources and the Alaska Water Treatment Guidance Manual. Both publications are referenced at 18 AAC 80.010(d), and information about how to review or obtain them is in the editor's note to 18 AAC 80.010.
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