Current through Register Vol. 48, No. 38, September 20, 2024
a)
Determination of the Mean Cryptosporidium Level
1) Following completion of the initial source
water monitoring required by Section
611.1001(a),
an unfiltered system supplier is required to have calculated the arithmetic
mean of all Cryptosporidium sample concentrations reported under Section
611.1001(a).
The supplier is required to have reported this value to the Agency for approval
no later than six months after the month the supplier is required to have
completed initial source water monitoring based on the applicable schedule set
forth in Section
611.1001(c).
2) Following completion of the second round
of source water monitoring required by Section
611.1001(b),
an unfiltered system supplier must calculate the arithmetic mean of all
Cryptosporidium sample concentrations reported under Section
611.1001(b).
The supplier must report this value to the Agency for approval no later than
six months after the month the supplier is required to complete the second
round of source water monitoring based on the applicable schedule set forth in
Section
611.1001(c).
3) If the monthly Cryptosporidium sampling
frequency varies, a supplier must first calculate a monthly average for each
month of monitoring. The supplier must then use these monthly average
concentrations, rather than individual sample concentrations, in the
calculation of the mean Cryptosporidium level in subsection (a)(1) or
(a)(2).
4) The report to the Agency
of the mean Cryptosporidium levels calculated under subsections (a)(1) and
(a)(2) must include a summary of the source water monitoring data used for the
calculation.
5) A failure to comply
with the conditions of subsection (a) is a violation of the treatment technique
requirement.
b)
Cryptosporidium Inactivation Requirements. An unfiltered system supplier must
provide the level of inactivation for Cryptosporidium specified in this
subsection, based on its mean Cryptosporidium levels, as determined under
subsection (a) and according to the applicable schedule set forth in Section
611.1013.
1) An unfiltered system supplier with a mean
Cryptosporidium level of 0.01 oocysts/l or less must provide at least 2-log
Cryptosporidium inactivation.
2) An
unfiltered system supplier with a mean Cryptosporidium level of greater than
0.01 oocysts/l must provide at least 3-log Cryptosporidium
inactivation.
c)
Inactivation Treatment Technology Requirements. An unfiltered system supplier
must use chlorine dioxide, ozone, or UV, as described in Section
611.1020,
to meet the Cryptosporidium inactivation requirements of this Section.
1) A supplier that uses chlorine dioxide or
ozone and fails to achieve the Cryptosporidium inactivation required in
subsection (b) on more than one day in the calendar month is in violation of
the treatment technique requirement.
2) A supplier that uses UV light and fails to
achieve the Cryptosporidium inactivation required in subsection (b)by meeting
the criteria in Section
611.1020(d)(3)(B)
is in violation of the treatment technique requirement.
d) Use of Two Disinfectants. An unfiltered
system supplier must meet the combined Cryptosporidium inactivation
requirements of this Section and Giardia lamblia and virus inactivation
requirements of Section
611.241 using a
minimum of two disinfectants, and each of two disinfectants must separately
achieve the total inactivation required for any of Cryptosporidium, Giardia
lamblia, or viruses.
BOARD NOTE: Derived from
40 CFR
141.712.
