R 325.10719e Disinfectant residuals, disinfection byproducts, and disinfection byproduct precursors; monitoring requirements.

Rule 719e. (1) This rule applies as set forth in R 325.10610b. All of the following provisions are general monitoring requirements: (a) Supplies shall take all samples during normal operating conditions. (b) Supplies may consider multiple wells drawing water from a single aquifer as 1 treatment plant for determining the minimum number of TTHM and HAA5 samples required, with department approval. This approval will be granted in writing if the supply can demonstrate that the finished water quality characteristic of all entry points to the distribution system drawing from the identified aquifer, whether served by multiple wells or a single well, are similar and are expected to react alike in terms of the formation of disinfection byproducts. To demonstrate this, the supply shall arrange for a study to be prepared by an individual or firm considered qualified to perform this work, such as a hydrogeologist, geologist, or engineer. All of the following provisions apply to the study: (i) The study shall consider well construction and geology, including all of the following: (A) Well locations marked on a topographical map. (B) Well depths. (C) Well logs showing geological strata, identifying water production zones, screened or slotted areas, and grouting of the annular space. (D) Static water levels. (E) Aquifer studies and maps. (F) Treatment applied. (ii) The study shall consider water characteristics and chemistry of each well including all of the following: (A) Field pH. (B) Field temperatures. (C) Specific conductivity. (D) Total organic carbon. (E) Analyses of common ions with a calculated cation/ion balance, such as calcium, magnesium, iron, manganese, sodium sulfate, alkalinity, and chloride. (iii) The department may require disinfection byproducts monitoring at various entry points to the distribution system to determine if the study conclusions are correct. (iv) Results of disinfection byproducts monitoring may be used instead of the study if all entry points to the distribution system drawing from the identified aquifer show that the levels are below the MCLs. (c) Failure to monitor in accordance with the monitoring plan required under subrule (5) of this rule is a monitoring violation. (d) Failure to monitor will be treated as a violation for the entire period covered by the annual average where compliance is based on a running annual average of monthly or quarterly samples or averages and the supply's failure to monitor makes it impossible to determine compliance with MCLs or MRDLs. (e) Supplies shall use only data collected under this rule to qualify for reduced monitoring. (2) All of the following provisions are monitoring requirements for disinfection byproducts: (a) All of the following provisions are TTHM and HAA5 monitoring requirements: (i) Supplies shall conduct routine monitoring at the frequency indicated in R 325.10719h. (ii) Supplies may reduce monitoring, except as otherwise provided, under R 325.10719j. (iii) To qualify for reduced monitoring for TTHM and HAA5 under R 325.10719j, subpart H supplies not subject to disinfection byproduct precursor monitoring under subrule (4) of this rule shall take monthly TOC samples every 30 days at a location before treatment. In addition to meeting other criteria for reduced monitoring in R 325.10719j, the source water TOC running annual average shall be less than or equal to 4.0 mg/L, based on the most recent 4 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 R 325.10719j, a supply may reduce source water TOC monitoring to quarterly TOC samples taken every 90 days at a location before treatment. (b) Community and nontransient noncommunity water supplies adding chlorine dioxide shall conduct monitoring for chlorite under all of the following provisions: (i) All of the following provisions are routine monitoring requirements: (A) Each day, supplies shall take samples at the entrance to the distribution system. For any daily sample that exceeds the chlorite MCL, the supply shall take additional samples in the distribution system the following day at the locations required by paragraph (ii) of this subdivision, in addition to the sample required at the entrance to the distribution system. (B) Each month, supplies shall take a 3-sample set in the distribution system. The supply shall take 1 sample at each of the following locations: (1) Near the first customer. (2) At a location representative of average residence time. (3) At a location reflecting maximum residence in the distribution system. Any additional routine sampling shall be conducted in the same manner, as 3-sample sets, at the specified locations. The supply may use the results of additional monitoring conducted under paragraph (ii) of this subdivision to meet the requirement for monitoring in this paragraph. (ii) On each day following a routine sample monitoring result that exceeds the chlorite MCL at the entrance to the distribution system, the supply shall take 3 chlorite distribution system samples at each of the following locations: (A) As close to the first customer as possible. (B) In a location representative of average residence time. (C) As close to the end of the distribution system as possible, reflecting maximum residence time in the distribution system. (iii) Chlorite monitoring at the entrance to the distribution system required by paragraph (i)(A) of this subdivision may not be reduced. Chlorite monitoring in the distribution system required by paragraph (i)(B) of this subdivision may be reduced to 1 3-sample set per quarter after 1 year of monitoring where no individual chlorite sample taken in the distribution system under paragraph (i)(B) of this subdivision has exceeded the chlorite MCL and the supply has not been required to conduct monitoring under paragraph (ii) of this subdivision. The supply may remain on the reduced monitoring schedule until either any of the 3 individual chlorite samples taken quarterly in the distribution system under paragraph (i)(B) of this subdivision exceeds the chlorite MCL or the supply is required to conduct monitoring under paragraph (ii) of this subdivision, at which time the supply shall revert to routine monitoring. (c) Supplies using ozone shall monitor for bromate as follows: (i) Supplies using ozone shall monitor for bromate by taking 1 sample per month at the entrance to the distribution system for each treatment plant in the supply using ozone. (ii) A supply required to monitor for bromate may reduce monitoring from monthly to quarterly, if the supply's running annual average bromate concentration is less than or equal to 0.0025 mg/L based on monthly bromate measurements under paragraph (i) of this subdivision for the most recent 4 quarters. The supply may remain on reduced monitoring as long as the running annual average of quarterly bromate sample are less than or equal to 0.0025 mg/L. If the running annual average bromate concentration is greater than 0.0025 mg/L, the supply shall resume routine monitoring required by paragraph (i) of this subdivision. (3) Both of the following provisions are monitoring requirements for disinfectant residuals: (a) Community and nontransient noncommunity water supplies adding chlorine or chloramines shall 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 R 325.10704 to R 325.10709 until March 31, 2016 and as specified in R 325.10704d to R 325.10704h beginning April 1, 2016. Subpart H supplies may use the results of residual disinfectant concentration sampling conducted under filtration sampling requirements of R 325.10720(4) instead of taking separate samples. Monitoring shall not be reduced. (b) All of the following provisions are chlorine dioxide monitoring requirements: (i) Community, nontransient noncommunity, and transient noncommunity water supplies that use chlorine dioxide shall monitor for chlorine dioxide by taking daily samples at the entrance to the distribution system. For any daily sample that exceeds the MRDL, the supply shall take samples in the distribution system the following day at the locations required by paragraph (ii) of this subdivision, in addition to the sample required at the entrance to the distribution system. (ii) On each day following a routine sample monitoring result that exceeds the MRDL, the supply shall take 3 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, that is, no booster chlorination, the supply shall take 3 samples as close to the first customer as possible, at intervals of at least 6 hours. If chlorine is used to maintain a disinfectant residual in the distribution system and there are 1 or more disinfection addition points after the entrance to the distribution system, that is, booster chlorination, the supply shall take 1 sample at each of the following locations: (A) As close to the first customer as possible. (B) In a location representative of average residence time. (C) As close to the end of the distribution system as possible, reflecting maximum residence time in the distribution system. (iii) Chlorine dioxide monitoring may not be reduced. (4) Monitoring requirements for disinfection byproduct precursors (DBPP) are as follows: (a) Subpart H supplies using conventional filtration shall monitor each treatment plant for TOC not later than the point of combined filter effluent turbidity monitoring and representative of the treated water. Supplies shall also monitor for TOC in the source water before any treatment at the same time as monitoring for TOC in the treated water. These samples (source water and treated water) are referred to as "paired samples." At the same time as the source water sample is taken, supplies shall monitor for alkalinity in the source water before any treatment. Supplies shall take 1 paired sample and 1 source water alkalinity sample per month per plant at a time representative of normal operating conditions and influent water quality. (b) Subpart H supplies with an average treated water TOC of less than 2.0 mg/l for 2 consecutive years, or less than 1.0 mg/l for 1 year, may reduce monitoring for both TOC and alkalinity to 1 paired sample and 1 source water alkalinity sample per plant per quarter. The supply shall revert to routine monitoring in the month following the quarter when the annual average treated water TOC is greater than or equal to 2.0 mg/l. (5) Supplies subject to this rule shall develop and implement a monitoring plan. The supply shall maintain the plan and make it available for inspection by the department and the general public not more than 30 days after the supply becomes subject to this rule, as indicated in R 325.10610b. Subpart H supplies serving more than 3,300 people shall submit a copy of the monitoring plan to the department not later than the date of the first report required under R 325.10719f. At a minimum, the plan shall include all of the following elements: (a) Specific locations and schedules for collecting samples for parameters included in R 325.10610b, R 325.10610c, or this rule. (b) The method the supply will use to calculate compliance with MCLs, MRDLs, and treatment techniques. (c) If approved for monitoring as a consecutive supply, or if providing water to a consecutive supply, under of R 325.10733, the sampling plan shall reflect the entire distribution system.