Louisiana Administrative Code › Title 51 - PUBLIC HEALTH-SANITARY CODE › Part XII - Water Supplies › Chapter 11 - Surface Water Treatment Rule › Subchapter C - Monitoring Requirements › Section XII-1127 - Disinfection Profiling

Current through Register Vol. 50, No. 6, June 20, 2024
A. All
				  public water systems using surface water or GWUDISW as its source of water
				  supply and serving at least 10,000 individuals shall perform a disinfection
				  profile of its disinfection practice on a continuous, daily basis. All public
				  water systems using surface water or GWUDISW as its source of water supply and
				  serving less than 10,000 individuals shall perform a disinfection profile of
				  its disinfection practice on a continuous, weekly basis.
1. Any system that meets the criteria of
				  Subsection A of this Section shall perform monitoring on each day [or, in the
				  case of systems serving less than 10,000 individuals, once each week (on the
				  same calendar day)] of operation to determine the total logs of inactivation of
Giardia lamblia
cysts, based upon the
				  CT99.9 (3-Log) values in Appendix E of the SWTR Guidance
				  Manual, as appropriate, through the entire treatment plant. Any system that
				  uses chloramines, ozone, or chlorine dioxide for primary disinfection shall
				  additionally calculate the total logs of inactivation of viruses for each day
				  of operation, based upon the CT99.99 (4-Log) values in
				  Appendix E of the SWTR Guidance Manual. Systems with more than one point of
				  disinfectant application shall conduct monitoring for each disinfection
				  segment. The following parameters shall be monitored:
a. the temperature of the disinfected water
				  at each disinfectant residual concentration sampling point during peak hourly
				  flow;
b. if the system uses free
				  chlorine, the pH of the disinfected water at each free chlorine residual
				  disinfectant concentration sampling point during peak hourly flow;
c. the disinfectant contact time(s) ("T") at
				  peak hourly flow at each residual disinfectant concentration sampling point
				  using approved mathematical computations as outlined in Appendix C of the SWTR
				  Guidance Manual or using the system's specific curve which is graphed as
				  "Detention Time (T10 in minutes) vs. Flow (in MGD)" (as
				  per the example shown in Figure C-4 of Appendix C of the SWTR Guidance Manual)
				  to determine the contact time based upon flow, subject to the following
				  additional requirements:
i. for systems
				  serving 3,300 persons or more, the disinfectant contact time(s) is to be
				  determined through the use of data developed from actual tracer studies
				  conducted on the system (see Paragraph 1119.C.1). [Theoretical contact time(s)
				  using baffling factors are not to be used for systems serving 3,300 persons or
				  more.];
ii. for systems serving
				  less than 3,300 persons, the disinfectant contact time(s) may be estimated
				  through the use of data developed in a theoretical manner by determining
				  pipeline capacities, treatment basin capacities, clearwell storage capacity,
				  storage tank capacities, etc., and applying the appropriate geometry and
				  baffling factor(s) (see Paragraph 1119.C.2)
;
d. the residual disinfectant
				  concentration(s) ("C") of the water before or at the first customer during peak
				  hourly flow;
(NOTE: If the treatment plant uses its own finished water
					 for potable purposes, the first customer may be the treatment plant itself.);
					 and
e. if the system uses
				  more than one point of disinfectant application before the first customer, the
				  system must determine the parameters identified in Subparagraphs a-d of this
				  Paragraph for each individual disinfection segment immediately prior to the
				  next point of disinfectant application during peak hourly flow so that a
				  cumulative CT value can be determined before the treated water reaches the
				  first customer.
(NOTE: If the treatment plant uses its own finished water
					 for potable purposes, the first customer may be the treatment plant
					 itself.)