567—43.10(455B) Enhanced filtration and disinfection requirements for surface water and IGW systems serving fewer than 10,000 people.
	43.10(1) General requirements.
	a. 	Applicability. The requirements of this rule constitute national primary drinking water regulations. This rule establishes requirements for filtration and disinfection that are in addition to criteria under which filtration and disinfection are required in 567—43.5(455B). The requirements of this rule are applicable beginning January 1, 2005, unless otherwise noted, to all public water systems using surface water or groundwater under the direct influence of surface water, in whole or in part, and which serve less than 10,000 people. This rule establishes or extends treatment technique requirements in lieu of maximum contaminant levels for the following contaminants: Giardia lamblia, viruses, heterotrophic plate count bacteria, Legionella, Cryptosporidium, and turbidity. The treatment technique requirements consist of installing and properly operating water treatment processes which reliably achieve:
	(1)	At least 99 percent (2 log) removal of Cryptosporidium between a point where the raw water is not subject to recontamination by surface water runoff and a point downstream before or at the first customer for filtered systems; and
	(2)	Compliance with the profiling and benchmark requirements in subrules 43.10(2) and 43.10(3).
	b. 	Prohibition of new construction of uncovered intermediate or finished water storage facilities. Systems that are required to comply with this rule may construct only covered intermediate or finished water storage facilities. For the purposes of this rule, an intermediate storage facility is defined as a storage facility or reservoir after the clarification treatment process.
	43.10(2) Disinfection profile.
	a. 	Applicability. A disinfection profile is a graphical representation of a system’s level of Giardia lamblia or virus inactivation measured during the course of a year. All systems required to comply with this rule must develop a disinfection profile unless the department determines that such a profile is unnecessary. Records must be maintained according to subrule 43.10(7).
	(1)	The department may approve the use of a more representative data set for disinfection profiling than the data set required in paragraph 43.10(2)“b.”
	(2)	The department may determine that a system’s profile is unnecessary only if a system’s TTHM and HAA5 levels are below 0.064 mg/L and 0.048 mg/L, respectively. To determine these levels, TTHM and HAA5 samples must be collected after January 1, 1998, during the month with the warmest water temperature, and at the point of maximum residence time in the distribution system. The department may approve the use of a more representative annual data set for purpose of determining applicability of the requirements of this subrule. The annual data set must be calculated on an annual average, of the arithmetic average of the quarterly averages of four consecutive quarters of monitoring. At least 25 percent of the samples collected in each quarter must be collected at the maximum residence time location in the distribution system.
1. For systems that provide water to other public water supplies, if the producing system meets the byproduct level requirements of less than 0.064 mg/L for TTHM and less than 0.048 mg/L for HAA5, it will not be required to develop a disinfection profile and benchmark unless:
	●	The consecutive system cannot meet in its distribution system the byproduct level requirements of less than 0.064 mg/L for TTHM and less than 0.048 mg/L for HAA5, and
	●	The producing system wants to make a significant change to its disinfection practices.
2. The department will then assign the requirement to the producing system to conduct the disinfection profiling study and determine a disinfection benchmark.
	b. 	Required elements of a disinfection profile.
	(1)	Collection of the following data for 12 consecutive months, beginning by July 1, 2003, for systems serving 500 to 9,999 people, and by January 1, 2004, for systems serving fewer than 500 people. A system must monitor the following parameters to determine the total log inactivation by using the analytical methods in paragraph 43.5(4)“a,” once per week on the same calendar day, over 12 consecutive months.
	1.	Temperature of the disinfected water at each residual disinfectant concentration sampling point during peak hourly flow, measured in degrees Celsius;
	2.	For systems using chlorine, the pH of the disinfected water at each residual disinfectant concentration sampling point during peak hourly flow, measured in standard pH units;
	3.	The disinfectant contact time (“T”) during peak hourly flow, measured in minutes; and
	4.	The residual disinfectant concentration(s) (“C”) of the water following each point of disinfection at a point(s) prior to each subsequent point of disinfection and at the entry point to the distribution system or at a location just prior to the first customer during peak hourly flows, measured in mg/L.
	(2)	The data collected in 43.10(2)“b”(1) must be used to calculate the weekly log inactivation, along with the CT99.9 tables listed in Appendix A. The system must calculate the total inactivation ratio as follows and multiply the value by 3.0 to determine log inactivation of Giardia lamblia:
	1.	If the system uses only one point of disinfectant application, it must determine:
	●	One inactivation ratio (CT calc/CT99.9) before or at the first customer during peak hourly flow, or
	●	Successive (CT calc/CT99.9) values, representing sequential inactivation ratios, between the point of disinfection application and a point before or at the first customer during peak hourly flow. Under this alternative, the system must calculate the total inactivation ratio by determining (CT calc/CT99.9) for each sequence and then adding the (CT calc/CT99.9) values together to determine (ƩCT calc/CT99.9).
	2.	If a system uses more than one point of disinfectant application before the first customer, the system must determine the (CT calc/CT99.9) value of each disinfection segment immediately prior to the next point of disinfectant application, or for the final segment, before or at the first customer, during peak hourly flow using the procedure specified in 43.10(2)“b”(2) “1,” second bulleted paragraph.
	3.	If a system uses chloramines, ozone, or chlorine dioxide for primary disinfection, the system must also calculate the inactivation logs for viruses and develop an additional disinfection profile for viruses using methods approved by the department.
	(3)	The weekly log inactivations are used to develop a disinfection profile, as follows:
	1.	The disinfection profile is developed by graphing each log inactivation data point versus time. Each log inactivation serves as a data point in the disinfection profile. The system will have obtained 52 measurements at a minimum, one for each week of the year.
	2.	The disinfection profile depicts the variation of microbial inactivation over the course of the year.
	3.	The system must retain the disinfection profile data both in a graphic form and in a spreadsheet, which must be available for review by the department.
	4.	This profile is used to calculate a disinfection benchmark if the system is considering changes to its disinfection practices.
	43.10(3) Disinfection benchmark.
	a. 	Applicability. Any system required to develop a disinfection profile under 43.10(2) must develop a disinfection benchmark prior to making any significant change in disinfection practice. The system must receive department approval before any significant change in disinfection practice is implemented. Records must be maintained according to subrule 43.10(7).
	b. 	Significant changes to disinfection practice. Significant changes to disinfection practice include:
	(1)	Changes to the point of disinfection;
	(2)	Changes to the disinfectant(s) used in the treatment plant;
	(3)	Changes to the disinfection process; or
	(4)	Any other modification identified by the department.
	c. 	Calculation of the disinfection benchmark. The system must calculate the disinfection benchmark in the following manner:
	(1)	Step 1. Using the data collected to develop the disinfection profile, the system must determine the average Giardia lamblia inactivation for each calendar month by dividing the sum of all Giardia lamblia inactivations for that month by the number of values calculated for that month.
	(2)	Step 2. The system must determine the lowest monthly average value out of the 12 values. This value becomes the disinfection benchmark.
	d. 	Information required for department approval of a change in disinfection practice. Any significant change in disinfection practice must have been approved by the department before the system institutes the change. The following information must be submitted by the system to the department as part of the consultation and approval process.
	(1)	A description of the proposed change;
	(2)	The disinfection profile for Giardia lamblia and, if necessary, viruses;
	(3)	The disinfection benchmark;
	(4)	An analysis of how the proposed change will affect the current levels of disinfection; and
	(5)	Any additional information requested by the department.
	e. 	Additional benchmark requirements if chloramines, ozone, or chlorine dioxide is used for primary disinfection. If a system uses chloramines, ozone, or chlorine dioxide for primary disinfection, the system must calculate the disinfection benchmark from the data collected for viruses to develop the disinfection profile in addition to the Giardia lamblia disinfection benchmark calculated in paragraph 43.10(3)“c.” This viral benchmark must be calculated in the same manner used to calculate the Giardia lamblia disinfection benchmark in paragraph 43.10(3)“c.”
	43.10(4) Combined filter effluent turbidity requirements. All systems using surface water or groundwater under the direct influence of surface water which serve less than 10,000 people must use filtration, and the turbidity limits that must be met depend upon the type of filtration used. Systems using lime softening may acidify representative combined filter effluent turbidity samples prior to analysis, using a protocol approved by the department.
	a. 	Conventional filtration treatment or direct filtration.
	(1)	Turbidity must be measured in the combined filter effluent as described in paragraphs 43.5(4)“a” and “b.”
	(2)	The turbidity in the combined filter effluent must be less than or equal to 0.3 NTU in 95 percent of the turbidity measurements taken each month.
	(3)	The turbidity in the combined filter effluent must never exceed 1 NTU at any time during the month. If at any time the combined filter effluent turbidity exceeds 1 NTU, either in a grab sample used for compliance or in a continuously monitored flow, the system must inform the department as soon as possible, but no later than 24 hours after the exceedance is known, in accordance with the public notification requirements under 567—subparagraphs 42.1(3)“b”(3) and 42.1(2)“a”(8).
	(4)	The monthly reporting requirements are listed in subrule 43.10(6).
	b. 	Slow sand filtration or diatomaceous earth filtration.
	(1)	Turbidity must be measured in the combined filter effluent as described in paragraphs 43.5(4)“a” and “b.”
	(2)	The combined filter effluent turbidity limits of subrule 43.5(3) must be met.
	(3)	The monthly reporting requirements are listed in subrule 43.10(6).
	c. 	Other alternative filtration technologies. By using pilot studies or other means, a system using alternative filtration must demonstrate to the satisfaction of the department that the system’s filtration, in combination with disinfection treatment, consistently achieves 99 percent removal of Cryptosporidium oocysts; 99.9 percent removal, inactivation, or a combination of both, of Giardia lamblia cysts; and 99.99 percent removal, inactivation, or a combination of both, of viruses. The department will then use the pilot study data to determine system-specific turbidity limits.
	(1)	Turbidity must be measured in the combined filter effluent as described in paragraphs 43.5(4)“a” and “b.”
	(2)	The turbidity must be less than or equal to a value set by the department in 95 percent of the combined filter effluent turbidity measurements taken each month, based on the pilot study. The value may not exceed 1 NTU.
	(3)	The combined filter effluent turbidity must never exceed a value set by the department, based on the pilot study. The value may not exceed 5 NTU.
	(4)	The monthly reporting requirements are listed in subrule 43.10(6).
	43.10(5) Individual filter turbidity requirements. All systems utilizing conventional filtration or direct filtration must conduct continuous monitoring of turbidity for each individual filter. Records must be maintained according to subrule 43.10(7).
	a. 	Continuous turbidity monitoring requirements. Following are the continuous turbidity monitoring requirements.
	(1)	Monitoring must be conducted using an approved method listed in paragraph 43.5(4)“a”;
	(2)	Calibration of turbidimeters must be conducted at least every 90 days with a primary standard. The calibration of each turbidimeter used for compliance must be verified at least once per week with a primary standard, secondary standards, or the manufacturer’s proprietary calibration confirmation device or by a method approved by the department. If the verification is not within plus or minus 0.05 NTU for measurements of less than or equal to 0.5 NTU, or within plus or minus 10 percent of measurements greater than 0.5 NTU, the turbidimeter must be recalibrated;
	(3)	Results of turbidity monitoring must be recorded at least every 15 minutes;
	(4)	Monthly reporting must be completed according to subrule 43.10(6); and
	(5)	Records must be maintained according to 43.10(7).
	b. 	Failure of continuous turbidity monitoring equipment. If there is a failure in the continuous turbidity monitoring equipment, the system must conduct grab sampling every four hours in lieu of continuous monitoring until the turbidimeter is back on-line. A system has a maximum of 14 days after failure to repair the equipment, or else the system is in violation. The system must notify the department within 24 hours of both when the turbidimeter was taken off-line and when it was returned on-line.
	c. 	Special provision for one-filter or two-filter systems. If a system has only one or two filters, it may conduct continuous monitoring of the combined filter effluent turbidity instead of individual effluent turbidity monitoring. The continuous monitoring of the combined filter effluent turbidity must meet the requirements listed in 43.10(5)“a” and “b.”
	d. 	Alternative turbidity levels for systems using lime softening. Systems using lime softening may apply to the department for alternative turbidity exceedance levels for the levels specified in 43.10(5)“e.” The system must be able to demonstrate to the satisfaction of the department that higher turbidity levels are due to lime carryover only, and not due to degraded filter performance.
	e. 	Requirements triggered by the individual filter turbidity monitoring data. Systems are required to conduct additional activities based upon their individual filter turbidity monitoring data, as listed in this paragraph.
	(1)	If the turbidity of an individual filter (or the turbidity of the combined filter effluent for a system with one or two filters, pursuant to 43.10(5)“c”) exceeds 1.0 NTU in two consecutive recordings taken 15 minutes apart, the system must report the following information in the monthly operation report to the department by the tenth day of the following month:
	1.	The filter number(s);
	2.	Corresponding date(s);
	3.	Turbidity value(s) which exceeded 1.0 NTU; and
	4.	The cause of the exceedance(s), if known.
	(2)	If the turbidity of an individual filter (or the turbidity of the combined filter effluent for a system with one or two filters, pursuant to 43.10(5)“c”) exceeds 1.0 NTU in two consecutive recordings 15 minutes apart in three consecutive months, the system must meet the following requirements:
	1.	The system must conduct a self-assessment of the filter(s) within 14 days of the day the filter exceeded 1.0 NTU in two consecutive measurements for the third straight month, unless a comprehensive performance evaluation as specified in the following paragraph is required. Two-filter systems that monitor the combined filter effluent turbidity instead of the individual filters must conduct a self-assessment of both filters.
	2.	The self-assessment must consist of at least the following components:
	●	Assessment of filter performance;
	●	Development of a filter profile;
	●	Identification and prioritization of factors limiting filter performance;
	●	Assessment of the applicability of corrections;
	●	Preparation of a filter self-assessment report;
	●	Date the self-assessment requirement was triggered; and
	●	Date the self-assessment was completed.
	(3)	If the turbidity of an individual filter (or the turbidity of the combined filter effluent for a system with one or two filters, pursuant to 43.10(5)“c”) exceeds 2.0 NTU in two consecutive recordings 15 minutes apart in two consecutive months, the system must meet the following requirements:
	1.	The system must arrange to have a comprehensive performance evaluation (CPE) conducted by the department or a third party approved by the department no later than 60 days following the day the filter exceeded 2.0 NTU in two consecutive measurements for the second straight month. The CPE report must be completed and submitted to the department within 120 days following the day the filter exceeded 2.0 NTU in two consecutive measurements for the second straight month.
	2.	A new CPE is not required if a CPE has been completed by the department or a third party approved by the department within the prior 12 months or if the system and department are jointly participating in an ongoing comprehensive technical assistance project at the system.
	(4)	The department may conduct a CPE at a system regardless of individual filter turbidity levels.
	43.10(6) Reporting requirements. The system must meet the following reporting requirements:
	a. 	Combined filter effluent turbidity monitoring.
	(1)	The following information must be reported in the monthly operation report to the department by the tenth day of the following month.
	1.	Total number of filtered water turbidity measurements taken during the month.
	2.	The number and percentage of filtered water turbidity measurements taken during the month which are less than or equal to the system’s required 95th percentile limit.
	3.	The date and analytical result of any turbidity measurements taken during the month which exceeded the maximum turbidity limit for the system, in addition to the requirements of (2).
	4.	The dates and summary of calibration and verification of all compliance turbidimeters.
	(2)	For an exceedance of the combined filter effluent maximum turbidity limit, the following requirements must be met.
	1.	If at any time the turbidity exceeds 1 NTU in representative samples of filtered water in a system using conventional filtration treatment or direct filtration, the system must consult with the department as soon as practical, but no later than 24 hours after the exceedance is known, in accordance with the public notification requirements under 567—subparagraph 42.1(3)“b”(3).
	2.	If at any time the turbidity in representative samples of filtered water exceeds the maximum level under subrule 43.5(3) for slow sand filtration or diatomaceous earth filtration, the system must consult with the department as soon as practical, but no later than 24 hours after the exceedance is known, in accordance with the public notification requirements under 567—subparagraph 42.1(3)“b”(3).
	3.	If at any time the turbidity in representative samples of filtered water exceeds the maximum level set by the department under paragraph 43.10(4)“c” for filtration technologies other than conventional filtration treatment, direct filtration, slow sand filtration, or diatomaceous earth filtration, the system must consult with the department as soon as practical, but no later than 24 hours after the exceedance is known, in accordance with the public notification requirements under 567—subparagraph 42.1(3)“b”(3).
	b. 	Individual filter effluent turbidity monitoring. The following information must be reported in the monthly operation report to the department by the tenth day of the following month, unless otherwise noted.
	(1)	That the system conducted individual filter turbidity monitoring during the month.
	(2)	For any filter that had two consecutive measurements taken 15 minutes apart that exceeded 1.0 NTU, the following information must be reported:
	1.	The filter number(s);
	2.	The corresponding dates;
	3.	The turbidity values that exceeded 1.0 NTU; and
	4.	The cause, if known, of the exceedance.
	(3)	If a self-assessment was required, the date it was triggered and the date the assessment was completed must be reported. If the self-assessment requirement was triggered in the last four days of the month, the information must be reported to the department by the 14th day of the following month.
	(4)	If a comprehensive performance evaluation was required, the date it was triggered must be reported. A copy of the CPE report must be submitted to the department within 120 days of when the CPE requirement was triggered.
	(5)	The dates and summary of calibration and verification of all compliance turbidimeters.
	c. 	Disinfection profiling. The following information must be reported to the department by January 1, 2004, for systems serving fewer than 500 people.
	(1)	Results of disinfection byproduct monitoring that indicate TTHM levels less than 0.064 mg/L and HAA5 levels less than 0.048 mg/L; or
	(2)	That the system has begun to collect the profiling data.
	d. 	Disinfection benchmarking. Before a system that was required to develop a disinfection profile makes a significant change to its disinfection practice, it must report the following information to the department, and the system must receive department approval before any significant change in disinfection practice is implemented.
	(1)	Description of the proposed change in disinfection practice;
	(2)	The system’s disinfection profile for Giardia lamblia and, if applicable, for viruses;
	(3)	The system’s disinfection benchmark; and
	(4)	An analysis of how the proposed change will affect the current levels of disinfection.
	43.10(7) Record-keeping requirements. The system must meet the following record-keeping requirements, in addition to the record-keeping requirements in 567—paragraph 42.4(3)“c” and 567—42.5(455B).
	a. 	Individual filter effluent turbidity requirements. The results of the individual filter effluent turbidity monitoring must be kept for at least three years.
	b. 	Disinfection profiling requirements. The results of the disinfection profile, including raw data and analysis, must be kept indefinitely.
	c. 	Disinfection benchmarking requirements. The results of the disinfection benchmark, including raw data and analysis, must be kept indefinitely.
[ARC 9915B, IAB 12/14/11, effective 1/18/12; ARC 3735C, IAB 4/11/18, effective 5/16/18]