Current through Register No. 13, March 27, 2025
(a) The system
owner shall use the profiling data from
Env-Ws
380.24 through
Env-Ws
380.25 to calculate a disinfection benchmark prior to
changing disinfection practices.
(b) Disinfection benchmarking shall be
conducted as follows:
(1) The owner of a
system required to develop a disinfection profile under the provisions of this
section shall consult with the department prior to making a significant change
to the system's disinfection practice;
(2) Significant changes to disinfection
practice shall include:
a. Changes to the
point of disinfection;
b. Changes
to the disinfectant(s) used in the treatment plant;
c. Changes to the disinfection process;
or
d. Any other disinfection
modification identified by the department; and
(3) The owner of a system shall submit the
following information to the department as part of the consultation process
identified in (b)(1) above:
a. A description
of the proposed change;
b. The
disinfection profile for giardia lamblia, and, if necessary, viruses, and the
disinfection benchmark as required by (d) below;
c. An analysis of how the proposed change
will affect the current levels of disinfection; and
d. Any additional information requested by
the department based on a determination that the information is needed to make
a fully informed decision.
(c) The department shall respond to the
request in writing and shall approve the change to the disinfectant practice if
it finds that such change complies with department rules and
statutes.
(d) The owner of a system
receiving department approval to modify the system's disinfection practice
shall calculate the disinfection benchmark using the
procedures specified in (1) and (2) below:
(1) For each year of profiling data collected
and calculated under (p) above, the system owner shall:
a. Determine the average giardia lamblia
inactivation for systems serving at least 10,000 for each calendar month for
each year of profiling data by dividing the sum of daily giardia lamblia logs
of inactivation by the number of values calculated for that month;
b. Determine the average giardia lamblia
inactivation for systems serving fewer than 10,000 for each calendar month of
profiling data by dividing the sum of weekly giardia lamblia logs of
inactivation for that month by the number of values calculated for that
month;
c. Determine the lowest
average monthly giardia lamblia inactivation for systems serving at least
10,000 in each year of profiling data; or
d. Determine the lowest average monthly
giardia lamblia inactivation for systems serving fewer than 10,000 in one year
of profiling data; and
(2) The disinfection benchmark shall be the
lowest monthly average value, for systems with one year of profiling data, or
the average of lowest monthly average values, for systems with more than one
year of profiling data, of the monthly logs of giardia lamblia inactivation in
each year of profiling data.
(e) A system ownerusing chloramines, chlorine
dioxide, or ozone for primary disinfection shall:
(1) Calculate the disinfection benchmark for
viruses using the method in (d) above; and
(2) Submit the information specified in
(b)(3) above, to the department within 10 days of obtaining the
information.
#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
)
