Use the tables in Sec. 141.74(b)(3)(v) to determine the appropriate CT99.9 value. Calculate the total inactivation ratio as follows, and multiply the value by 3.0 to determine log inactivation of Giardia lamblia: ------------------------------------------------------------------------
(a) Uses only one point of (1) One inactivation ratio (CTcalc/
disinfectant application. CT99.9) before or at the first
customer during peak hourly flow
or
(2) Successive CTcalc/CT99.9 values,
representing sequential
inactivation ratios, between the
point of disinfectant application
and a point before or at the first
customer during peak hourly flow.
Under this alternative, your system
must calculate the total
inactivation ratio by determining
(CTcalc/CT99.9) for each sequence
and then adding the (CTcalc/CT99.9)
values together to determine
([Sigma]CTcalc/CT99.9).(b) Uses more than one point of The (CTcalc/CT99.9) value of each
disinfectant application before disinfection segment immediately
the first customer. prior to the next point of
disinfectant application, or for
the final segment, before or at the
first customer, during peak hourly
flow using the procedure specified
in paragraph (a)(2) of this
section.------------------------------------------------------------------------ [67 FR 1839, Jan. 14, 2002, as amended at 69 FR 38856, June 29, 2004]