Hawaii Administrative Rules
Title 11 - DEPARTMENT OF HEALTH
Subtitle 1 - GENERAL DEPARTMENTAL PROVISIONS
Chapter 20 - RULES RELATING TO PUBLIC WATER SYSTEMS
Section 11-20-45.1 - Disinfectant residuals, disinfection byproducts, and disinfection byproduct precursors

(i) Dissolved Organic Carbon (DOC). Standard Method 5310 B or 5310 B-00 (High-Temperature Combustion Method) or Standard Method 5310 C or 5310 C-00 (Persulfate-Ultraviolet or Heated-Persulfate Oxidation Method) or Standard Method 5310 D or 5310 D-00 (Wet-Oxidation Method) or EPA Method 415.3 Revision 1.1. DOC samples must be filtered through the 0.45 um pore diameter filter as soon as practical after sampling, not to exceed forty-eight hours. After filtration, DOC samples must be acidified to achieve pH less than or equal to 2 with minimal addition of the acid specified in the method or by the instrument manufacturer. Acidified DOC samples must be analyzed within twenty-eight days of sample collection. Inorganic carbon must be removed from the samples prior to analysis. Water passed through the filter prior to filtration of the sample must serve as the filtered blank. This filtered blank must be analyzed using procedures identical to those used for analysis of the samples and must meet the following criteria: DOC less than 0.5 mg/L.

(ii) Ultraviolet Absorption at 254 nm (UV254). Method 5910 B or 5910 B-00 (Ultraviolet Absorption Method) or EPA Method 415.3 Revision 1.1. UV absorption must be measured at 253.7 nm (may be rounded off to 254 nm). Prior to analysis, UV254 samples must be filtered through a 0.45 um pore-diameter filter. The pH of UV254 samples may not be adjusted. Samples must be analyzed as soon as practical after sampling, not to exceed forty-eight hours.

(i) Routine monitoring. Systems must monitor at the frequency indicated in Appendix B entitled "Routine Monitoring Frequency For TTHM and HAA5 (HAR 11-20-45.1(c)(2)(A))", dated January 1, 2002, located at the end of this chapter and made a part of this section.

(ii) Systems may reduce monitoring, except as otherwise provided, in accordance with Appendix C entitled "Reduced Monitoring Frequency For TTHM and HAA5 (HAR 11-20-45.1(c)(2)(B)) ", dated January 1, 2002, located at the end of this chapter and made a part of this section.

(iii) Monitoring requirements for source water TOC. In order to qualify for reduced monitoring for TTHM and HAA5 under clause (ii), Subpart H systems not monitoring under the provisions of paragraph (c)(4) must take monthly TOC samples every thirty days at a location prior to any treatment, beginning April 1, 2008 or earlier, if specified by the director. In addition to meeting other criteria for reduced monitoring in clause (ii), the source water TOC running annual average must be <4.0 mg/L (based on the most recent four quarters of monitoring) on a continuing basis at each treatment plant to reduce or remain on reduced monitoring for TTHM and HAA5. Once qualified for reduced monitoring for TTHM and HAA5 under clause (ii), a system may reduce source water TOC monitoring to quarterly TOC samples taken every ninety days at a location prior to any treatment.

(iv) Systems on a reduced monitoring schedule may remain on that reduced schedule as long as the average of all samples taken in the year (for systems which must monitor quarterly) or the result of the sample (for systems which must monitor no more frequently than annually) is no more than 0.060 mg/L and 0.045 mg/L for TTHMs and HAA5, respectively. Systems that do not meet these levels must resume monitoring at the minimum frequency identified in Appendix B (minimum monitoring frequency column) in the quarter immediately following the monitoring period in which the system exceeds 0.060 mg/L and 0.045 mg/L for TTHMs and HAA5, respectively. For systems using only ground water not under the direct influence of surface water and serving fewer than 10,000 persons, if either the TTHM annual average is > 0.080 mg/L or the HAA5 annual average is > 0.060 mg/L, the system must go to the increased monitoring identified in Appendix B (sample location column) in the quarter immediately following the monitoring period in which the system exceeds 0.080 mg/L or 0.060 mg/L for TTHMs or HAA5 respectively.

(v) Systems on increased monitoring may return to routine monitoring if, after at least one year of monitoring their TTHM annual average is <= 0.060 mg/L and their HAA5 annual average is <= 0.045 mg/L.

(vi) The director may return a system to routine monitoring at the director's discretion.

(i) Routine daily monitoring. Systems must take daily samples at the entrance to the distribution system. For any daily sample that exceeds the chlorite MCL, the system must take additional samples in the distribution system the following day at the locations required by clause (iii) in addition to the sample required at the entrance to the distribution system.

(ii) Routine monthly monitoring. Systems must take a three-sample set each month in the distribution system. The system must take one sample at each of the following locations: near the first customer, at a location representative of average residence time, and at a location reflecting maximum residence time in the distribution system. Any additional routine sampling must be conducted in the same manner (as three-sample sets, at the specified locations). The system may use the results of additional monitoring conducted under clause (iii) to meet the requirement for monitoring under this clause.

(iii) Additional monitoring. On each day following a routine sample monitoring result that exceeds the chlorite MCL at the entrance to the distribution system, the system is required to take three chlorite distribution system samples at the following locations: as close to the first customer as possible, in a location representative of average residence time, and as close to the end of the distribution system as possible (reflecting maximum residence time in the distribution system).

(iv) Reduced monitoring at entrance to distribution system. Chlorite monitoring at the entrance to the distribution system required by clause (i) may not be reduced.

(v) Reduced monitoring in distribution system. Chlorite monitoring in the distribution system required by clause (ii) may be reduced to one three-sample set per quarter after one year of monitoring where no individual chlorite sample taken in the distribution system under clause (ii) has exceeded the chlorite MCL and the system has not been required to conduct monitoring under clause (iii). The system may remain on the reduced monitoring schedule until either any of the three individual chlorite samples taken quarterly in the distribution system under clause (ii) exceeds the chlorite MCL or the system is required to conduct monitoring under clause (iii), at which time the system must revert to routine monitoring.

(i) Routine monitoring. Community and nontransient non-community systems using ozone, for disinfection or oxidation, must take one sample per month for each treatment plant in the system using ozone. Systems must take samples monthly at the entrance to the distribution system while the ozonation system is operating under normal conditions.

(ii) Reduced monitoring. Until March 31, 2009, systems required to analyze for bromate may reduce monitoring from monthly to quarterly, if the system's average source water bromide concentration is less than 0.05 mg/L based on representative monthly bromide measurements for one year. The system may remain on reduced bromate monitoring until the running annual average source water bromide concentration, computed quarterly, is equal to or greater than 0.05 mg/L based upon representative monthly measurements. If the running annual average source water bromide concentration is equal to or greater than 0.05 mg/L, the system must resume routine monitoring required by clause (i) in the following month. Beginning April 1, 2009, systems may no longer use the provisions of this clause to qualify for reduced monitoring. A system required to analyze for bromate may reduce monitoring from monthly to quarterly, if the system's running annual average bromate concentration is <=0.0025 mg/L based on monthly bromate measurements under clause (i) for the most recent four quarters, with samples analyzed using Method 317.0 Revision 2.0, 326.0 or 321.8. If the running annual average bromate concentration is >0.0025 mg/L, the system must resume routine monitoring required by clause (i).

(i) Routine monitoring. Beginning April 1, 2016, community and non-transient non-community water systems that use chlorine or chloramines must measure the residual disinfectant level in the distribution system at the same point in the distribution system and at the same time as total coliforms are sampled, as specified in sections 11-20-9.1(d) and (e). Public water systems which filter either a surface water source or a GWUDI source may use the results of residual disinfectant concentration sampling conducted under section 11-20-46(d)(2)(B)(iii), in lieu of taking separate samples.

(ii) Reduced monitoring. Monitoring may not be reduced.

(i) Routine monitoring. Community, nontransient non-community, and transient non-community water systems that use chlorine dioxide for disinfection or oxidation must take daily samples at the entrance to the distribution system. For any daily sample that exceeds the MRDL, the system must take samples in the distribution system the following day at the locations required by clause (ii), in addition to the sample required at the entrance to the distribution system.

(ii) Additional monitoring. On each day following a routine sample monitoring result that exceeds the MRDL, a system covered by this paragraph is required to take three chlorine dioxide distribution system samples. If chlorine dioxide or chloramines are used to maintain a disinfectant residual in the distribution system, or if chlorine is used to maintain a disinfectant residual in the distribution system and there are no disinfection addition points after the entrance to the distribution system (i.e., no booster chlorination), the system must take three samples as close to the first customer as possible, at intervals of at least six hours. If chlorine is used to maintain a disinfectant residual in the distribution system and there are one or more disinfection addition points after the entrance to the distribution system (i.e., booster chlorination), the system must take one sample at each of the following locations: as close to the first customer as possible, in a location representative of average residence time, and as close to the end of the distribution system as possible (reflecting maximum residence time in the distribution system). All sampling locations shall be approved by the director.

(iii) Reduced monitoring. Chlorine dioxide monitoring may not be reduced.

(i) For systems monitoring quarterly, compliance with MCLs in section 11-20-4.1 must be based on a running annual arithmetic average, computed quarterly, of quarterly arithmetic averages of all samples collected by the system as prescribed by subsections (c)(2)(A).

(ii) For systems monitoring less frequently than quarterly, systems demonstrate MCL compliance if the average of samples taken that year under the provisions of subsection (c)(2)(A) does not exceed the MCLs in section 11-20.4.1. If the average of these samples exceeds the MCL, the system must increase monitoring to once per quarter per treatment plant and such a system is not in violation of the MCL until it has completed one year of quarterly monitoring, unless the result of fewer than four quarters of monitoring will cause the running annual average to exceed the MCL, in which case the system is in violation at the end of that quarter. Systems required to increase monitoring frequency to quarterly monitoring must calculate compliance by including the sample which triggered the increased monitoring plus the following three quarters of monitoring.

(iii) If the running annual arithmetic average of quarterly averages covering any consecutive four-quarter period exceeds the MCL, the system is in violation of the MCL and must notify the public pursuant to section 11-20-18 or 40 C.F.R. § 141.202, whichever is effective for your system, in addition to reporting to the director pursuant to subsection (e).

(iv) If a PWS fails to complete four consecutive quarters of monitoring (e.g., when the PWS has not been operating for four quarters), compliance with the MCL for the last four-quarter compliance period must be based on an average of the available data.

(i) Compliance must be based on a running annual arithmetic average, computed quarterly, of monthly averages of all samples collected by the system under subsection (c)(3)(A). If the average covering any consecutive four-quarter period exceeds the MRDL, the system is in violation of the MRDL and must notify the public pursuant to section 11-20-18, in addition to reporting to the director pursuant to subsection (e).

(ii) In cases where systems switch between the use of chlorine and chloramines for residual disinfection during the year, compliance must be determined by including together all monitoring results of both chlorine and chloramines in calculating compliance. Reports submitted pursuant to subsection (e) must clearly indicate which residual disinfectant was analyzed for each sample.

(i) Acute violations. Compliance must be based on consecutive daily samples collected by the system under subsection (c)(3)(B). If any daily sample taken at the entrance to the distribution system exceeds the MRDL, and on the following day one (or more) of the three samples taken in the distribution system exceed the MRDL, the system is in violation of the MRDL and must take immediate corrective action to lower the level of chlorine dioxide below the MRDL and must notify the public pursuant to the procedures for acute health risks in section 11-20-18(b)(2)(D) in addition to reporting to the director pursuant to subsection (e). Failure to take samples in the distribution system the day following an exceedance of the chlorine dioxide MRDL at the entrance to the distribution system will also be considered an MRDL violation and the system must notify the public of the violation in accordance with the provisions for acute violations in section 11-20-18(b)(2)(D) in addition to reporting to the director pursuant to subsection (e).

(ii) Nonacute violations. Compliance must be based on consecutive daily samples collected by the system under subsection (c)(3)(B). If any two consecutive daily samples taken at the entrance to the distribution system exceed the MRDL and all distribution system samples taken are below the MRDL, the system is in violation of the MRDL and must take corrective action to lower the level of chlorine dioxide below the MRDL at the point of sampling and will notify the public pursuant to the procedures for nonacute health risks in section 11-20-18 in addition to reporting to the director pursuant to subsection (e). Failure to monitor at the entrance to the distribution system the day following an exceedance of the chlorine dioxide MRDL at the entrance to the distribution system is also an MRDL violation and the system must notify the public of the violation in accordance with the provisions for nonacute violations under section 11-20-18 in addition to reporting to the director pursuant to subsection (e).

(i) The system's source water TOC level, measured according to subsection (b)(4)(C), is less than 2.0 mg/L, calculated quarterly as a running annual average.

(ii) The system's treated water TOC level, measured according to subsection (b)(4)(C), is less than 2.0 mg/L, calculated quarterly as a running annual average.

(iii) The system's source water TOC level, measured according to subsection (b)(4)(C), is less than 4.0 mg/L, calculated quarterly as a running annual average; the source water alkalinity, measured according to subsection (b)(4)(A), is greater than 60 mg/L (as CaCO3), calculated quarterly as a running annual average; and either the TTHM and HAA5 running annual averages are no greater than 0.040 mg/L and 0.030 mg/L, respectively; or prior to the effective date for compliance in subsection (a)(2), the system has made a clear and irrevocable financial commitment not later than the effective date for compliance in subsection (a)(2) to use technologies that will limit the levels of TTHMs and HAA5 to no more than 0.040 mg/L and 0.030 mg/L, respectively. Systems must submit evidence of a clear and irrevocable financial commitment, in addition to a schedule containing milestones and periodic progress reports for installation and operation of appropriate technologies, to the director for approval not later than the effective date for compliance in subsection (a)(2). These technologies must be installed and operating not later than June 30, 2005. Failure to install and operate these technologies by the date in the approved schedule will constitute a violation of National Primary Drinking Water Regulations.

(iv) The TTHM and HAA5 running annual averages are no greater than 0.040 mg/L and 0.030 mg/L, respectively, and the system uses only chlorine for primary disinfection and maintenance of a residual in the distribution system.

(v) The system's source water SUVA, prior to any treatment and measured monthly according to subsection (b)(4)(D), is less than or equal to 2.0 L/mg-m, calculated quarterly as a running annual average.

(vi) The system's finished water SUVA, measured monthly according to subsection (b)(4)(D), is less than or equal to 2.0 L/mg-m, calculated quarterly as a running annual average.

(i) Softening that results in lowering the treated water alkalinity to less than 60 mg/L (as CaCO3), measured monthly according to subsection (b)(4)(A) and calculated quarterly as a running annual average.

(ii) Softening that results in removing at least 10 mg/L of magnesium hardness (as CaCO3), measured monthly according to subparagraph (b)(4)(F) and calculated quarterly as an annual running average.

(i) Alternate enhanced coagulation level is defined as coagulation at a coagulant dose and pH as determined by the method described in this subparagraph such that an incremental addition of 10 mg/L of alum (or equivalent amount of ferric salt) results in a TOC removal of less than or equal to 0.3 mg/L. The per cent removal of TOC at this point on the "TOC removal versus coagulant dose" curve is then defined as the minimum TOC removal required for the system. Once approved by the director, this minimum requirement supersedes the minimum TOC removal required by the table in subparagraph (B). This requirement will be effective until such time as the director approves a new value based on the results of a new bench- and pilot-scale test. Failure to achieve State-set alternative minimum TOC removal levels is a violation of National Primary Drinking Water Regulations.

(ii) Bench- or pilot-scale testing of enhanced coagulation must be conducted by using representative water samples and adding 10 mg/L increments of alum (or equivalent amounts of ferric salt) until the pH is reduced to a level less than or equal to the enhanced coagulation Step 2 target pH shown in the following table:

(iii) For waters with alkalinities of less than 60 mg/L for which addition of small amounts of alum or equivalent addition of iron coagulant drives the pH below 5.5 before significant TOC removal occurs, the system must add necessary chemicals to maintain the pH between 5.3 and 5.7 in samples until the TOC removal of 0.3 mg/L per 10 mg/L alum added (or equivalent addition of iron coagulant) is reached.

(iv) The system may operate at any coagulant dose or pH necessary (consistent with other NPDWRs) to achieve the minimum TOC per cent removal approved under subparagraph (C).

(v) If the TOC removal is consistently less than 0.3 mg/L of TOC per 10 mg/L of incremental alum dose at all dosages of alum (or equivalent addition of iron coagulant), the water is deemed to contain TOC not amenable to enhanced coagulation. The system may then apply to the director for a waiver of enhanced coagulation requirements.

(i) Determine actual monthly TOC per cent removal, equal to: (1-(treated water TOC/source water TOC) ) x 100

(ii) Determine the required monthly TOC per cent removal (from either the table in paragraph (2)(B) or from paragraph (2)(C) ).

(iii) Divide the value in clause (i) by the value in clause (ii).

(iv) Add together the results of clause (iii) for the last twelve months and divide by twelve.

(v) If the value calculated in clause (iv) is less than 1.00, the system is not in compliance with the 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 (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).