Indiana Administrative Code › Title 327 - WATER POLLUTION CONTROL DIVISION › Article 8 - PUBLIC WATER SUPPLY › Rule 2.6 - Enhanced Filtration and Disinfection › Section 2.6-19 - Additional filtration toolbox components; requirements for microbial toolbox components; enhanced treatment for Cryptosporidium

Current through July 10, 2024
Authority: IC 13-13-5; IC 13-14-8-7; IC 13-14-9; IC
				  13-18-3-2; IC 13-18-16
Affected: IC 13-18-3-11
Sec. 19.
(a) A PWS
				using additional filtration toolbox components may receive Cryptosporidium
				treatment credit of up to 2.0-log for individual bag or cartridge filters and
				up to 2.5-log credit for bag or cartridge filters operated in series if the PWS
				complies with the following:
(1) The PWS
				shall report to the commissioner the results of challenge testing that meets
				the requirements of subdivision (3)(B) through (3)(I).
(2) The filters must treat the entire plant
				flow taken from a Subpart H system source.
(3) The PWS shall meet the following
				criteria:
(A) The Cryptosporidium treatment
				credit awarded to bag or cartridge filters must be based on the removal
				efficiency demonstrated during challenge testing that meets the following:
(i) Challenge testing is conducted according
				to clauses (B) through (I).
(ii) A
				factor of safety equal to:
(AA) 1-log for
				individual bag or cartridge filters; and
(BB) 0.5-log for bag or cartridge filters in
				series; must be applied to challenge testing results to determine removal
				credit.
(iii) A PWS may
				use challenge testing results conducted prior to January 5, 2006, if the prior
				testing was consistent with the criteria specified under clauses (B) through
				(I).
(B) Challenge
				testing must be performed according to the following:
(i) Testing must be performed on full-scale
				bag or cartridge filters and the associated filter housing or pressure vessel
				that are identical in material and construction to the filters and housing the
				PWS will use for removal of Cryptosporidium.
(ii) Bag or cartridge filters must be
				challenge tested in the same configuration that the PWS will use, either as
				individual filters or as a series configuration of filters.
(C) Challenge testing must be
				conducted using Cryptosporidium or a surrogate, either of which are referred to
				during challenge testing as the challenge particulate, according to the
				following:
(i) A surrogate, if used, must be a
				microorganism that is removed not more efficiently than
				Cryptosporidium.
(ii) The
				concentration of the challenge particulate must be determined using a method
				capable of discreetly quantifying the specific microorganism or surrogate used
				in the test.
(iii) Gross
				measurements, such as turbidity, may not be used.
(D) The maximum feed water concentration that
				may be used during a challenge test must be based on the detection limit of the
				challenge particulate in the filtrate (filtrate detection limit) and must be
				calculated using the following equation:
Maximum Feed Concentration = 1 ×
				  104
												× (Filtrate Detection Limit)
(E) Challenge testing must be
				conducted at the maximum design flow rate for the filter as specified by the
				manufacturer.
(F) Each filter
				evaluated must be tested for a duration sufficient to reach one hundred percent
				(100%) of the terminal pressure drop in order to establish the maximum pressure
				drop under which the filter can be used to comply with the requirements of
				sections 7 through 18 of this rule, this section, and sections 20 through 22 of
				this rule.
(G) Removal efficiency
				of a filter must be determined from the results of the challenge test and
				expressed in terms of log removal values using the following equation:
LRV = LOG10(Cf)
				  - LOG10(Cp)
Where: LRV = log removal value demonstrated during challenge
				  testing
Cf = the feed concentration measured
				  during the challenge test
Cp = the filtrate concentration
				  measured during the challenge test
In applying this equation, the same units must be used for
				  the feed and filtrate concentrations. If the challenge particulate is not
				  detected in the filtrate, then the term Cp must be set
				  equal to the detection limit.
(H) Each filter tested must be challenged
				with the challenge particulate during three (3) periods over the filtration
				cycle, as follows:
(i) Within the first two
				(2) hours of start-up of a new filter.
(ii) When the pressure drop is between
				forty-five percent (45%) and fifty-five percent (55%) of the terminal pressure
				drop.
(iii) At the end of the cycle
				after the pressure drop has reached one hundred percent (100%).
An LRV must be calculated for each of the challenge periods
				  listed under items (i) and (ii) for each filter tested. The LRV for the filter
				  (LRVfilter) must be assigned the value of the minimum
				  LRV observed during the three (3) challenge periods for that filter.
(I) Overall removal
				efficiency for the filter product line shall be established as follows:
(i) If fewer than twenty (20) filters are
				tested, the overall removal efficiency for the filter product line must be set
				equal to the lowest LRVfilter among the filters
				tested.
(ii) If twenty (20) or more
				filters are tested, the following apply:
(AA)
				Overall removal efficiency for the filter product line must be set equal to the
				tenth percentile of the set of LRVfilter values for the
				various filters tested.
(BB) The
				percentile is defined by (i/(n+1)) where i is the rank of n individual data
				points ordered lowest to highest.
(CC) If necessary, the tenth percentile may
				be calculated using linear interpolation.
(J) If a previously tested filter is modified
				in a manner that could change the removal efficiency of the filter product
				line, challenge testing to demonstrate the removal efficiency of the modified
				filter must be:
(i) conducted; and
(ii) submitted to the commissioner.