179 Neb. Admin. Code, ch. 19, § 008

Current through September 17, 2024

Section 179-19-008 - DISINFECTION BENCHMARK

008.01 Who Must Develop a Disinfection Benchmark

Systems that use surface water or ground water under the direct influence of surface water that are required to develop a disinfection profile under 179 NAC 19-007.01 through 19-007.07 must develop a disinfection benchmark if they decide to make a significant change to their disinfection practice. These systems must consult with the Director for approval before implementing a significant disinfection practice change.

008.02 Significant changes to disinfection practices include:

1. Changes to the point of disinfection;

2. Changes to the disinfectant(s) used in the treatment plant; or

3. Changes to the disinfection process.

008.03 If a system is considering a significant change to its disinfection practice, the system must calculate a disinfection benchmark(s) as described in 179 NAC 19-008.04 and 19-008.05 and provide the benchmark(s) to the Director. Systems may only make a significant disinfection practice change after consulting with the Director for approval. Systems must submit the following information to the Director as part of the consultation and approval process:

1. A description of the proposed change;

2. The disinfection profile for Giardia iambiia (and, if necessary, viruses) and disinfection benchmark; and

3. An analysis of how the proposed change will affect the current levels of disinfection.

008.04 Calculating the disinfection benchmark

Systems making a significant change to their disinfection practice must calculate a disinfection benchmark using the procedure specified in the following table.

To Calculate a Disinfection Benchmark Your System Must Perform the Following Steps

Step 1: Using the data your system collected to develop the disinfection profile, 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.

Step 2: Determine the lowest monthly average value out of the twelve values. This value becomes the disinfection benchmark.

008.05 Systems That Use Chloramines, Ozone, or Chlorine Dioxide for Primary Disinfection

These systems must calculate the disinfection benchmark from the data the system collected for viruses to develop the disinfection profile in addition to the Giardia lamblia disinfection benchmark calculated under 179 NAC 19-008.04. This viral benchmark must be calculated in the same manner used to calculate the Giardia lamblia disinfection benchmark in 179 NAC 19-008.04.

179 Neb. Admin. Code, ch. 19, § 008