HAR §11-20-45.1. (B) Systems may use the provisions in this subparagraph in lieu of the calculations in subparagraph (A) to determine compliance with TOC per cent removal requirements

(i) In any month that the system's treated or source water TOC level, measured according to subsection (b)(4)(C), is less than 2.0 mg/L, the system may assign a monthly value of 1.0 in lieu of the value calculated in subparagraph (A)(iii) when calculating compliance under the provisions of subparagraph (A). (ii) In any month that a system practicing softening removes at least 10 mg/L of magnesium hardness (as CaCO₃), the system may assign a monthly value of 1.0 in lieu of the value calculated in subparagraph (A)(iii) when calculating compliance under the provisions of subparagraph (A). (iii) In any month that the system's source water SUVA, prior to any treatment and measured according to subsection (b)(4)(D), is less than or equal to 2.0 L/mg-m, the system may assign a monthly value of 1.0 in lieu of the value calculated in subparagraph (A)(iii) when calculating compliance under the provisions of subparagraph (A). (iv) In any month that the system's finished water SUVA, measured according to subsection (b)(4)(D), is less than or equal to 2.0 L/mg-m, the system may assign a monthly value of 1.0 in lieu of the value calculated in subparagraph 20-196 3376 §11-20-45.2 (A) (iii) when calculating compliance under the provisions of subparagraph (A). (v) In any month that a system practicing enhanced softening lowers alkalinity below 60 mg/L (as CaCO₃), the system may assign a monthly value of 1.0 in lieu of the value calculated in subparagraph (A) (iii) when calculating compliance under the provisions of subparagraph (A). (C) Public water systems with a surface water source or a GWUDI source using conventional filtration treatment may also comply with the requirements of this subsection by meeting the criteria in paragraphs (1) (B) or (1) (C). (4) Treatment technique requirements for DBP precursors. The Administrator identifies the following as treatment techniques to control the level of disinfection byproduct precursors in drinking water treatment and distribution systems: for public water systems with a surface water source or a GWUDI source using conventional treatment, enhanced coagulation or enhanced softening. [Eff and comp 11/30/02; am and compiled 12/16/05; am and comp 11/28/11; comp 5/2/14; comp OCT 29 2020] (Auth: HRS §§340E-2, 340E-9) (Imp: HRS §§340E-2, 340E-9; 42 U.S.C. §§300f, 300g-1, 300g-2, 300g-3, 300g- 4, 300g-5, 300g-6, 300j-4, 300j-9, 300j-11; 40 C.F.R. §141.130, §141.131, §141.132, §141.133, §141.134, §141.135) §11-20-45.2 Initial Distribution System Evaluations. (a) General requirements. (1) The requirements of this section constitute national primary drinking water regulations. The regulations in this section establish 20-197 3376 1 §11-20-45.2 monitoring and other requirements for identifying Stage 2 Disinfection Byproduct compliance monitoring locations for determining compliance with maximum contaminant levels for total trihalomethanes (TTHM) and haloacetic acids (five) (HAA5). You must use an Initial Distribution System Evaluation (IDSE) to determine locations with representative high TTHM and HAA5 concentrations throughout your distribution system. IDSEs are used in conjunction with, but separate from, section 11-20-45.1 compliance monitoring, to identify and select Stage 2 Disinfection Byproduct compliance monitoring locations. (2) Applicability. You are subject to these requirements if your system is a community water system that uses a primary or residual disinfectant other than ultraviolet light or delivers water that has been treated with a primary or residual disinfectant other than ultraviolet light; or if your system is a nontransient noncommunity water system that serves at least 10,000 people and uses a primary or residual disinfectant other than ultraviolet light or delivers water that has been treated with a primary or residual disinfectant other than ultraviolet light. (3) Schedule. You must comply with the requirements of this section on the schedule in the following table. 20-198 13376 §11-20-45.2 | If you serve this population | You must submit your standard monitoring plan or system specific study plan^{1} or 40/30 certification^{2} to the State by or receive very small system waiver from the State | You must complete your standard monitoring or system specific study by | You must submit your IDSE report to the State by^{3} | | --- | --- | --- | --- | | Systems that are not part of a combined distribution system and systems that serve the largest population in the combined distribution system | | | | | ≥100,000 | October 1, 2006 | September 30, 2008 | January 1, 2009 | | 50,000-99,999 | April 1, 2007 | March 31, 2009 | July 1, 2009 | | 10,000-49,999 | October 1, 2007 | September 30, 2009 | January 1, 2010 | | <10,000 (CWS only) | April 1, 2008 | March 31, 2010 | July 1, 2010 | 20-199 3376 1 §11-20-45.2 | Other systems that are part of a combined distribution system | | | | | --- | --- | --- | --- | | Wholesale system or consecutive system | -at the same time as the system with the earliest compliance date in the combined distribution system | -at the same time as the system with the earliest compliance date in the combined distribution system | -at the same time as the system with the earliest compliance date in the combined distribution system | ¹If, within 12 months after the date identified in this column, the State does not approve your plan or notify you that it has not yet completed its review, you may consider the plan that you submitted as approved. You must implement that plan and you must complete standard monitoring or a system specific study no later than the date identified in the third column. ²You must submit your 40/30 certification under subsection (d) by the date indicated. ³If, within three months after the date identified in this column (nine months after the date identified in this column if you must comply on the schedule with a service population of between 10,000 and 49,999), the State does not approve your IDSE report or notify you that it has not yet completed its review, you may consider the report that you submitted as approved and you must implement the recommended Stage 2 Disinfection Byproduct monitoring as required. For the purpose of the schedule in this paragraph, the State may determine that the combined distribution system does not include certain consecutive systems based on factors such as receiving water from a wholesale system only on an emergency basis or receiving only a small percentage and small volume of water from a wholesale system. The State may also determine that the combined distribution system does not include certain wholesale systems based on 20-200 3376 §11-20-45.2 factors such as delivering water to a consecutive system only on an emergency basis or delivering only a small percentage and small volume of water to a consecutive system. (4) You must conduct standard monitoring that meets the requirements in subsection (b), or a system specific study that meets the requirements in subsection (c), or certify to the State that you meet 40/30 certification criteria under subsection (d), or qualify for a very small system waiver under subsection (e). (A) You must have taken the full complement of routine TTHM and HAA5 compliance samples required of a system with your population and source water under section 11-20-45.1 (or you must have taken the full complement of reduced TTHM and HAA5 compliance samples required of a system with your population and source water under section 11-20-45.1 if you meet reduced monitoring criteria under section 1-20- 45.1) during the period specified in paragraph (d)(1) to meet the 40/30 certification criteria in subsection (d). You must have taken TTHM and HAA5 samples under subsections 11-20-45.1(b) and (c) to be eligible for the very small system waiver in subsection (e). (B) If you have not taken the required samples, you must conduct standard monitoring that meets the requirements in subsection (b), or a system specific study that meets the requirements in subsection (c). (5) You must use only the analytical methods specified in subsection 11-20-45.1(b), or otherwise approved by EPA for monitoring under this section, to demonstrate 20-201 3376