Section Env-Ws 380.25 - Disinfection Profiling for Systems Which Serve Less than 10,000 People(a) The owner of a community or non-transient non-community public water system subject to the requirements of Env-Ws 380.23 and which serves fewer than 10,000 people shall comply with the requirements in (b) through (d) below.(b) The system shall develop a disinfection profile unless the department determines that the system's profile is unnecessary. The department shall determine that a system's profile is unnecessary if a system's TTHM and HAA5 levels are below 0.064 mg/L and 0.048 mg/L, respectively.(c) In accordance with 40 CFR 141.531, to determine whether a disinfection profile is required, TTHM and HAA5 samples shall be collected as follows: (1) After January 1, 1998;(2) During the month with the warmest temperature; and(3) At the point of maximum residence time in the distribution system.(d) The department shall approve the use of a more representative data set for disinfection profiling than the data set required under Env-Ws 380.25(e).(e) A system owner required to profile under (b) above shall conduct disinfection profiling as follows: (1) The system owner shall develop a disinfection profile of its disinfection practice for a period of up to one year;(2) The system owner shall monitor weekly;(3) The system owner shall monitor on the same day of the week for a period of 52 consecutive weeks for the parameters listed in (e)(8) below to determine the total logs of inactivation, expressed as log inactivation, for each day of monitoring, based on the CT99.9 values specified in Tables 380-2 through 380-9 as applicable, through the entire treatment plant;(4) The log inactivations shall be used to develop a disinfection profile;(5) As required by 40 CFR 141.532(a), if a system serves between 500 and 9,999 people it shall begin to collect data no later than July 1, 2003;(6) As required by 40 CFR 141.532(a), if a system serves fewer than 500 people it shall begin to collect data no later than January 1, 2004;(7) The system owner shall conduct the monitoring required in (e), above as follows: a. A system with a single point of disinfectant application prior to entrance to the distribution system shall conduct the monitoring in (e)(8) below; andb. A system with more than one point of disinfectant application shall conduct the monitoring in (e)(8) below for each disinfection segment; and(8) The system owner shall monitor the parameters necessary to determine the total inactivation ratio, using analytical methods described in Env-Ws 380.13, as follows: a. The temperature of the disinfected water shall be measured at each residual disinfectant concentration sampling point during peak hourly flow;b. If the system uses chlorine, the pH of the disinfected water shall be measured at least once per day at each chlorine residual disinfectant concentration sampling point during peak hourly flow;c. The disinfectant contact time(s) (T) shall be determined during peak hourly flow; andd. The residual disinfectant concentration(s) (C) of the water before or at the first customer and prior to each additional point of disinfection shall be measured during peak hourly flow.(f) A system owner may submit a written request to the department to use existing operational data in lieu of the monitoring conducted under the provisions of (e) above.(g) The written request shall include the following:(1) The water system name;(2) The water system EPA number;(3) The most recent data for the past year; and(4) A profile generated using the operational data specified in (3) above.(h) The data specified in (e) above shall be representative of giardia lamblia inactivation through the entire treatment plant and not just of certain treatment segments.(i) The department shall determine whether the operational data is substantially equivalent to data collected under the provisions of (e) above.(j) Until the department approves the request identified in (g) above, the system owner shall conduct monitoring under the provisions of (e), above.(k) To develop a disinfection profile, a system owner shall calculate the total inactivation ratio as follows: (1) If a system uses only one point of disinfectant application, the system owner shall determine the total inactivation ratio for the disinfection segment by: a. Determining one CTcalc/CT99.9 (inactivation ratio) before or at the first customer during peak hourly flow; orb. Determining successive sequential inactivation ratios, between the point of disinfectant application and a point before or at the first customer during peak hourly flow;(2) Under (k)(1) b. above, a system owner shall calculate the S CTcalc/CT99.9 (total inactivation ratio) by determining the inactivation ratios for each sequence and then adding the inactivation ratio values together to determine the total inactivation ratio;(3) If a system uses more than one point of disinfectant application before the first customer, the system owner shall determine the CT 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 and the inactivation ratio value of each segment and the total inactivation ratio shall be calculated using the method in (1) above; and(4) The system owner shall determine the total logs of inactivation by multiplying the value calculated in (k)(1) or (3) above by 3.0.(l) The owner of a system that uses chloramines, chlorine dioxide, or ozone for primary disinfection shall also calculate the logs of inactivation for viruses and develop an additional disinfection profile for viruses using methods approved by the department.(m) Each log inactivation shall serve as a data point in a system disinfection profile.(n) The system owner shall collect and retain disinfection profile data in the form of a graphor as a spreadsheet and have the data available when the department conducts a sanitary survey pursuant to Env-Ws 306.N.H. Code Admin. R. Env-Ws 380.25
#5098, eff 3-18-91, EXPIRED 3-18-97
New. #6521, eff 6-4-97 (See Revision Note at chapter heading for Env-Ws 300); ss by #8352, eff 5-14-05 (formerly part of Env-Ws 380.28 )