327 IAC 8-2.6-19 - Additional filtration toolbox components; requirements for microbial toolbox components; enhanced treatment for Cryptosporidium
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.
(b) The
following requirements apply to the use of membrane filtration for
Cryptosporidium treatment credit:
(1) A PWS
may receive Cryptosporidium treatment credit for membrane filtration according
to the following:
(A) The PWS meets the
criteria of this subsection.
(B)
Membrane cartridge filters that meet the definition of membrane filtration in
327 IAC 8-2-1 are
eligible for this credit.
(C) The
level of treatment credit a PWS receives is equal to the lower of the values
determined under the following:
(i) The
removal efficiency demonstrated during challenge testing conducted under
subdivision (2).
(ii) The maximum
removal efficiency that can be verified through direct integrity testing used
with the membrane filtration process under the conditions in subdivision
(3).
(2) The
PWS shall comply with the following regarding challenge testing in order to be
eligible for Cryptosporidium treatment credit:
(A) Conduct challenge testing on the membrane
used by the PWS to evaluate removal efficiency.
(B) Report the results of challenge testing
to the commissioner.
(C) A PWS may
use data from challenge testing conducted prior to January 5, 2006, if the
prior testing was consistent with the criteria under clause (D).
(D) Challenge testing must be conducted
according to the following criteria:
(i)
Challenge testing must be conducted on either a:
(AA) full-scale membrane module that is
identical in material and construction to the membrane modules used in the
PWS's treatment facility; or
(BB)
smaller-scale membrane module that is identical in material and similar in
construction to the full-scale module.
A module is defined as the smallest component of a membrane unit in which a specific membrane surface area is housed in a device with a filtrate outlet structure.
(ii) Challenge testing must be conducted
using Cryptosporidium oocysts or a surrogate either of which are referred to
during challenge testing as the challenge particulate, according to the
following:
(AA) A surrogate, if used, must be
a microorganism that is removed not more efficiently than
Cryptosporidium oocysts.
(BB) The concentration of the challenge
particulate, in both the feed and filtrate water, must be determined using a
method capable of discretely quantifying the specific challenge particulate
used in the test.
(CC) Gross
measurements, such as turbidity, may not be used.
(iii) The maximum feed water concentration
that may be used during a challenge test is based on the detection limit of the
challenge particulate in the filtrate and must be determined according to the
following equation:
Maximum Feed Concentration = 3.16 × 106 × (Filtrate Detection Limit)
(iv) Challenge testing must be
conducted under representative hydraulic conditions at the maximum design flux
and maximum design process recovery specified by the manufacturer for the
membrane module, where:
(AA) flux is defined
as the throughput of a pressure driven membrane process expressed as flow per
unit of membrane area; and
(BB)
recovery is defined as the volumetric percent of feed water that is converted
to filtrate over the course of an operating cycle uninterrupted by events such
as chemical cleaning or a solids removal process like backwashing.
(v) Removal efficiency of a
membrane module must be calculated from the challenge test results and
expressed as a log removal value according to 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 for the purpose of calculating the LRV. An LRV must be calculated for each membrane module evaluated during the challenge test.
(vi) The overall removal efficiency of a
membrane filtration process demonstrated during challenge testing must be
expressed as a log removal value (LRVC-Test) and
established according to the following:
(AA)
If fewer than twenty (20) modules are tested, then
LRVC-Test is equal to the lowest of the representative
LRVs among the modules tested.
(BB)
If twenty (20) or more modules are tested, then
LRVC-Test is equal to the tenth percentile of the
representative LRVs among the modules tested. The percentile is defined by
(i/(n+1)) where i is the rank of n individual data points ordered lowest to
highest. If necessary, the tenth percentile can be calculated using linear
interpolation.
(vii) The
PWS shall establish a quality control release value (QCRV) according to the
following:
(AA) The challenge test must
establish a QCRV for a nondestructive performance test that demonstrates the
Cryptosporidium removal capability of the membrane filtration module.
(BB) The performance test must be applied to
each production membrane module used by the system that was not directly
challenge tested in order to verify Cryptosporidium removal
capability.
(CC) Production modules
that do not meet the established QCRV are not eligible for the treatment credit
demonstrated during the challenge test. (viii) If a previously tested membrane
is modified in a manner that could change the removal efficiency of the
membrane or the applicability of the nondestructive performance test and
associated QCRV, additional challenge testing to demonstrate the removal
efficiency of, and determine a new QCRV for, the modified membrane must be
conducted and submitted to the commissioner.
(3) A PWS shall conduct direct
integrity testing that meets the following criteria:
(A) For the purpose of this section, a direct
integrity test is defined as a physical test applied to a membrane unit in
order to identify and isolate integrity breaches, for example, one (1) or more
leaks that could result in contamination of the filtrate.
(B) Direct integrity testing must be
conducted in a manner that demonstrates a removal efficiency equal to or
greater than the removal credit awarded to the membrane filtration
process.
(C) Direct integrity
testing must meet the following requirements:
(i) The direct integrity test must be
independently applied to each membrane unit in service. A membrane unit is
defined as a group of membrane modules that share common valving that allows
the unit to be isolated from the rest of the system for the purpose of
integrity testing or other maintenance.
(ii) The direct integrity method must have a
resolution of at least three (3) micrometers (µm) or less, where
resolution is defined as the size of the smallest integrity breach that
contributes to a response from the direct integrity test.
(iii) The direct integrity test must have a
sensitivity sufficient to verify the log treatment credit awarded to the
membrane filtration process by the commissioner, where sensitivity is defined
as the maximum log removal value that can be reliably verified by a direct
integrity test. Sensitivity must be determined using the approach in either of
the following, as applicable to the type of direct integrity test the system
uses:
(AA) For direct integrity tests that
use an applied pressure or vacuum, the direct integrity test sensitivity must
be calculated according to the following equation:
LRVDIT = LOG10 (Qp/(VCF X Qbreach))
Where: LRVDIT = the sensitivity of the direct integrity test
Qp = total design filtrate flow from the membrane unit
Qbreach = flow of water from an integrity breach associated with the smallest integrity test response that can be reliably measured
VCF = volumetric concentration factor
The volumetric concentration factor is the ratio of suspended solids concentration on the high pressure side of the membrane relative to that in the feed water.
(BB) For
direct integrity tests that use a particulate or molecular marker, the direct
integrity test sensitivity must be calculated according to the following
equation:
LRVDIT = LOG10(Cf) - LOG10(Cp)
Where: LRVDIT = the sensitivity of the direct integrity test
Cf = the typical feed concentration of the marker used in the test
Cp = the filtrate concentration of the marker from an integral membrane unit
(iv) A PWS shall establish a control limit
within the sensitivity limits of the direct integrity test that is indicative
of an integral membrane unit capable of meeting the removal credit awarded by
the commissioner.
(v) If the result
of a direct integrity test exceeds the control limit established under item
(iv), the PWS:
(AA) shall remove the membrane
unit from service;
(BB) shall
conduct a direct integrity test to verify any repairs; and
(CC) may return the unit to service only if
the direct integrity test is within the established control limit.
(vi) A PWS shall conduct direct
integrity testing on each membrane unit at a frequency of not less than once
each day that the membrane unit is in operation. The commissioner may approve
less frequent direct integrity testing based on:
(AA) demonstrated process
reliability;
(BB) the use of
multiple barriers effective for Cryptosporidium; or
(CC) reliable process safeguards.
(4) A PWS
shall conduct continuous indirect integrity monitoring that meets the following
criteria:
(A) For the purpose of this
section, indirect integrity monitoring is defined as monitoring some aspect of
filtrate water quality that is indicative of the removal of particulate
matter.
(B) A PWS that implements
continuous direct integrity testing of membrane units in accordance with the
criteria under subdivision (3)(C)(i) through (3)(C)(v) is not subject to the
requirements of this subdivision for continuous indirect integrity
monitoring.
(C) A PWS shall submit
a monthly report to the commissioner that includes the following:
(i) A summary of all continuous indirect
integrity monitoring results triggering direct integrity testing.
(ii) The corrective action that was taken in
each case that direct integrity testing was triggered.
(D) Continuous indirect integrity monitoring
must be conducted on each membrane unit according to the following criteria:
(i) Unless the commissioner approves an
alternative parameter, continuous indirect integrity monitoring must include
continuous filtrate turbidity monitoring.
(ii) Continuous monitoring must be conducted
at a frequency of not less than once every fifteen (15) minutes.
(iii) Continuous monitoring must be
separately conducted on each membrane unit.
(iv) If indirect integrity monitoring
includes turbidity and if the filtrate turbidity readings are above
fifteen-hundredths (0.15) NTU for a period greater than fifteen (15) minutes
(for example, two (2) consecutive fifteen (15) minute readings are above
fifteen-hundredths (0.15) NTU), direct integrity testing must immediately be
performed on the associated membrane unit as specified under subdivision
(3)(C)(i) through (3)(C)(v).
(v) If
indirect integrity monitoring includes an alternative parameter approved by the
commissioner under item (i) and if the alternative parameter exceeds the
control limit approved by the commissioner for a period greater than fifteen
(15) minutes, direct integrity testing must immediately be performed on the
associated membrane units as specified under subdivision (3)(C)(i) through
(3)(C)(v).
(c) A PWS may receive 0.5-log Cryptosporidium
treatment credit for a separate second stage of filtration if the following are
met:
(1) The separate second stage of
filtration must consist of:
(A)
sand;
(B) dual media;
(C) granular activated carbon (GAC);
or
(D) other fine grain media;
following granular media filtration if the commissioner approves.
(2) To
be eligible for this credit, the PWS shall meet the following:
(A) The first stage of filtration must be
preceded by a coagulation step.
(B)
Both filtration stages must treat the entire plant flow taken from a:
(i) surface water source; or
(ii) ground water under the direct influence
of surface water source.
(3) A cap, for example, a cap comprised of
GAC, on a single stage of filtration is not eligible for this credit.
(4) The commissioner shall approve the
treatment credit based on an assessment of the design characteristics of the
filtration process.
(d)
A PWS may receive 2.5-log Cryptosporidium treatment credit for a slow sand
filtration process that follows a separate stage of filtration if the following
are met:
(1) Both filtration stages must
treat the entire plant flow taken from a:
(A)
surface water source; or
(B) ground
water under the direct influence of surface water source.
(2) No disinfectant residual is present in
the influent water of the slow sand filtration process.
(3) This treatment credit is not available
where treatment credit is awarded to slow sand filtration used as a primary
treatment process.
(4) The
commissioner shall approve the treatment credit based on an assessment of the
design characteristics of the filtration process.
Notes
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