Section 179-25-012 - BIN CLASSIFICATION FOR FILTERED SYSTEMS012.01 Following completion of required source water monitoring, filtered systems must calculate a Cryptosporidium bin concentration for each plant for which monitoring was required. Calculation of the bin concentration must use the Cryptosporidium results reported under 179 NAC 25-004.01 or 40 CFR 141 Subpart W and must follow the following procedures:012.02 Procedures for Bin Classification 25-012.02A For systems that collect a total of at least 48 samples, the bin concentration is equal to the arithmetic mean of all sample concentrations.25-012.02B For systems that collect a total of at least 24 samples, but not more than 47 samples, the bin concentration is equal to the highest arithmetic mean of all sample concentrations in any 12 consecutive months during which Cryptosporidium samples were collected.25-012.02C For systems that serve fewer than 10,000 people and monitor for Cryptosporidium for only one year (i.e., collect 24 samples in 12 months), the bin concentration is equal to the arithmetic mean of all sample concentrations.25-012.02D For systems with plants operating only part of the year that monitor fewer than 12 months per year under 179 NAC 25-004.04, the bin concentration is equal to the highest arithmetic mean of all sample concentrations during any year of Cryptosporidium monitoring.25-012.02E If the monthly Cryptosporidium sampling frequency varies, systems must first calculate a monthly average for each month of monitoring. Systems must then use these monthly average concentrations, rather than individual sample concentrations, in the applicable calculation for bin classification in 179 NAC 25-012.02A through 25-012.02D.012.03 Filtered systems must determine their bin classification from the following table and using the calculated Cryptosporidium bin concentration. BIN CLASSIFICATION TABLE FOR FILTERED SYSTEMS
| For systems that are: | With a Cryptosporidium bin concentration of . . | The bin classification is . . |
| . . . required to monitor for Cryptosporidium under 179 NAC 25-004 or systems that monitored Cryptosporidium under 40 CFR 141 Subpart W | Cryptosporidium < 0.075 oocysts/L 0.075 oocysts/L <=Cryptosporidium < 1.0oocysts/L 1.0 oocysts/L <=Cryptosporidium < 3.0oocysts/L Cryptosporidium >= 3.0 oocysts/L | Bin 1 Bin 2 Bin 3 Bin 4 |
| . . . serving fewer than 10,000 people and NOT required to monitor for Cryptosporidium under 179 NAC 25-004.01D or 40 CFR 141 Subpart W | NA | Bin 1 |
012.04 Bin Classification Report 25-012.04A Filtered systems must report their bin classification to the Department for approval no later than six months after the system is required to complete source water monitoring.25-012.04B The bin classification report to the Department must include a summary of source water monitoring data and the calculation procedure used to determine bin classification.012.05 Failure to comply with the conditions of 179 NAC 25-012.04 is a violation of the treatment technique requirement.179 Neb. Admin. Code, ch. 25, § 012