Section 327IAC8-2.6-11. Bin classification for filtered systems; treatment technique requirements; enhanced treatment for Cryptosporidium

   (a) Following completion of the initial round of source water monitoring required under 40 CFR 141.701(a), as incorporated by reference in section 8(a)(1) of this rule, each filtered PWS shall calculate an initial Cryptosporidium bin concentration for each plant for which monitoring was required by:

(1) using the Cryptosporidium results reported under 40 CFR 141.701(a), as incorporated by reference in section 8(a)(1) of this rule; and

(2) following the procedures in subsection (b).

  (b) The following calculations shall be used to determine bin concentrations for the PWS as described:

(1) For a PWS that collects at least forty-eight (48) samples, the bin concentration is equal to the arithmetic mean of all sample concentrations.

(2) For a PWS that collects at least twenty-four (24) samples, but not more than forty-eight (48) samples, the bin concentration is equal to the highest arithmetic mean of all sample concentrations in any twelve (12) consecutive months during which Cryptosporidium samples were collected.

(3) For a PWS serving fewer than ten thousand (10,000) people that monitors for Cryptosporidium for only one (1) year, the bin concentration is equal to the arithmetic mean of all sample concentrations.

(4) For a PWS that has a plant that:

(A) operates only part of the year; and

(B) monitors fewer than twelve (12) months per year under 40 CFR 141.701(e), as incorporated in section 8(a)(1) of this rule;

the bin concentration is equal to the highest arithmetic mean of all sample concentrations during any year of Cryptosporidium monitoring.

(5) If the monthly Cryptosporidium sampling frequency varies, a PWS shall:

(A) first calculate a monthly average for each month of monitoring; and

(B) then use the monthly average concentrations calculated under clause (A), rather than individual sample concentrations, in the applicable calculation for bin classification in subdivisions (1) through (4).

  (c) A filtered system shall determine its initial bin classification from the following table and using the Cryptosporidium bin concentration calculated under subsections (a) and (b):

Table 11

For systems that are:	With a Cryptosporidium bin concentration of:1	The bin classification is:
Required to monitor for Cryptosporidium under 40 CFR 141.701, as incorporated by reference in section 8(a)(1) of this rule.	Cryptosporidium < 0.075 oocysts/L	Bin 1
	0.075 oocysts/L ≤ Cryptosporidium < 1.0 oocysts/L	Bin 2
	1.0 oocysts/L ≤ Cryptosporidium < 3.0 oocysts/L	Bin 3
	Cryptosporidium ≥3.0 oocysts/L	Bin 4
Serving fewer than 10,000 people and NOT required to monitor for Cryptosporidium under 40 CFR 141.701(a)(4), as incorporated by reference in section 8(a)(1) of this rule.	NA	Bin 1

¹Based on calculations in subsection (a) or (d), as applicable.

  (d) Following completion of the second round of source water monitoring required under 40 CFR 141.701(b), as incorporated by reference in section 8(a)(1) of this rule, a filtered PWS shall do the following:

(1) Recalculate its Cryptosporidium bin concentration using the Cryptosporidium results reported under 40 CFR 141.701(b), as incorporated by reference in section 8(a)(1) of this rule and following the procedures in subsection (b)(1) through (b)(4).

(2) Redetermine its bin classification using the bin concentration calculated under subdivision (1) and Table 11 in subsection (c).

  (e) A filtered PWS shall report its bin classifications as follows:

(1) A PWS shall report its initial bin classification under subsection (c) to the commissioner for approval not later than six (6) months after the PWS is required to complete initial source water monitoring based on the schedule in 40 CFR 141.701(c), as incorporated by reference in section 8(a)(1) of this rule.

(2) A PWS shall report its bin classification under subsection (d) to the commissioner for approval not later than six (6) months after the PWS is required to complete the second round of source water monitoring based on the schedule in 40 CFR 141.701(c), as incorporated by reference in section 8(a)(1) of this rule.

(3) The bin classification report to the commissioner must include the following:

(A) A summary of source water monitoring data.

(B) The calculation procedure used to determine bin classification.

  (f) Failure to comply with the conditions of subsection (e):

(1) is a violation of the treatment technique requirement; and

(2) requires public notification under 327 IAC 8-2.1.

(Water Pollution Control Division; 327 IAC 8-2.6-11; filed May 7, 2010, 9:30 a.m.: 20100602-IR-327080198FRA)