R 325.10719j Disinfection byproducts; reduced monitoring.

Rule 719j. (1) The community or nontransient noncommunity water supply that is subject to disinfection byproducts requirements of R 325.10610d may reduce monitoring any time the LRAA is less than or equal to 0.040 mg/L for TTHM and less than or equal to 0.030 mg/L for HAA5 at all monitoring locations. The supply may only use data collected under R 325.10610b to R 325.10610d, R 325.10719e to R 325.10719f, and R 325.10719h to R 325.10719n to qualify for reduced monitoring. In addition, the source water annual average TOC level, before treatment, shall be less than or equal to 4.0 mg/L at each treatment plant treating surface water or groundwater under the direct influence of surface water, based on monitoring conducted under either R 325.10719e(2)(a)(3) or R 325.10719e(4). Reduced monitoring shall be to the level specified in the following table: Source Water Type Population size category Monitoring Frequency * Distribution system monitoring location per monitoring period Subpart H less than 500 monitoring may not be reduced Subpart H 500 to 3,300 per year 1 TTHM and 1 HAA5 sample: 1 at the location and during the quarter with the highest TTHM single measurement, 1 at the location and during the quarter with the highest HAA5 single measurement; 1 dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter. Subpart H 3,301 to 9,999 per year 2 dual sample sets: 1 at the location and during the quarter with the highest TTHM single measurement, 1 at the location and during the quarter with the highest HAA5 single measurement. Subpart H 10,000 to 49,999 per quarter 2 dual sample sets at the locations with the highest TTHM and highest HAA5 LRAAs. Subpart H 50,000 to 249,999 per quarter 4 dual sample sets--at the locations with the 2 highest TTHM and 2 highest HAA5 LRAAs. Subpart H 250,000 to 999,999 per quarter 6 dual sample sets--at the locations with the 3 highest TTHM and 3 highest HAA5 LRAAs. Subpart H 1,000,000 to 4,999,999 per quarter 8 dual sample sets--at the locations with the 4 highest TTHM and 4 highest HAA5 LRAAs. Subpart H greater than or equal to 5,000,000 per quarter 10 dual sample sets--at the locations with the 5 highest TTHM and 5 highest HAA5 LRAAs. Groundwater less than 500 every third year 1 TTHM and 1 HAA5 sample: 1 at the location and during the quarter with the highest TTHM single measurement, 1 at the location and during the quarter with the highest HAA5 single measurement; 1 dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter. Groundwater 500 to 9,999 per year 1 TTHM and 1 HAA5 sample: 1 at the location and during the quarter with the highest TTHM single measurement, 1 at the location and during the quarter with the highest HAA5 single measurement; 1 dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter. Groundwater 10,000 to 99,999 per year 2 dual sample sets: 1 at the location and during the quarter with the highest TTHM single measurement, 1 at the location and during the quarter with the highest HAA5 single measurement. Groundwater 100,000 to 499,999 per quarter 2 dual sample sets; at the locations with the highest TTHM and highest HAA5 LRAAs. Groundwater greater than or equal to 500,000 per quarter 4 dual sample sets at the locations with the 2 highest TTHM and 2 highest HAA5 LRAAs. * Supplies on quarterly monitoring shall take dual sample sets every 90 days. (2) The supply may remain on reduced monitoring as long as the TTHM LRAA less than or equal to 0.040 mg/L and the HAA5 LRAA less than or equal to 0.030 mg/L at each monitoring location (for supplies with quarterly reduced monitoring) or each TTHM sample less than or equal to 0.060 mg/L and each HAA5 sample less than or equal to 0.045 mg/L (for supplies with annual or less frequent monitoring). In addition, the source water annual average TOC level, before treatment, shall be less than or equal to 4.0 mg/L at each treatment plant treating surface water or groundwater under the direct influence of surface water, based on monitoring conducted under either R 325.10719e(2)(a)(iii) or R 325.10719e(4). (3) If the LRAA based on quarterly monitoring at a monitoring location exceeds either 0.040 mg/L for TTHM or 0.030 mg/L for HAA5 or if the annual (or less frequent) sample at a location exceeds either 0.060 mg/L for TTHM or 0.045 mg/L for HAA5, or if the source water annual average TOC level, before treatment, is greater than 4.0 mg/L at a treatment plant treating surface water or groundwater under the direct influence of surface water, the supply shall resume routine monitoring under R 325.10719h or begin increased monitoring if R 325.10719k applies. (4) The department may return the supply to routine monitoring under R 325.10732.