(a) A system will receive the treatment
credits listed in Appendix B to Subchapter L. Microbial Toolbox Summary Table:
Options, Treatment Credits and Criteria, by meeting the conditions for
microbial toolbox components described in subsections (b)-(q). A system shall
apply these treatment credits to meet the treatment technique requirements
listed in section §
109.1203 (relating to bin
classification and treatment technique requirements).
(b)
Watershed control
program. Filtered systems receive 0.5-log
Cryptosporidium treatment credit for implementing a watershed
control program that meets the requirements of this subsection. This credit may
not be used to maintain the additional log removal credits specified in §
109.1203. This credit may only be
applied in addition to the toolbox options used to meet the minimum log removal
and may apply in lieu of a toolbox option for which credit has been temporarily
revoked. Unfiltered systems are not eligible for this credit.
(1) Systems that intend to apply for the
watershed control program credit shall notify the Department of this intent at
least 2 years prior to the treatment compliance date applicable to the system
in §
109.1203(k)-(o).
(2) Systems shall submit to the Department a
proposed watershed control plan at least 1 year before the applicable treatment
compliance date in §
109.1203(k)-(o).
The Department will approve the watershed control plan for the system to
receive watershed control program treatment credit. The watershed control plan
must include the following elements:
(i)
Identification of an "area of influence" outside of which the likelihood of
Cryptosporidium or fecal contamination affecting the treatment
plant intake is not significant. This is the area to be evaluated in future
watershed surveys under paragraph (4)(ii).
(ii) Identification of both potential and
actual sources of Cryptosporidium contamination and an
assessment of the relative impact of these sources on the system's source water
quality.
(iii) An analysis of the
effectiveness and feasibility of control measures that could reduce
Cryptosporidium loading from sources of contamination to the
system's source water.
(iv) A
statement of goals and specific actions the system will undertake to reduce
source water Cryptosporidium levels. The plan must explain how
the actions are expected to contribute to specific goals, identify watershed
partners and their roles, identify resource requirements and commitments, and
include a schedule for plan implementation with deadlines for completing
specific actions identified in the plan.
(3) Systems with existing watershed control
programs (that is, programs in place on January 5, 2006) are eligible to seek
this credit. Their watershed control plans must meet the criteria in paragraph
(2) and must specify ongoing and future actions that will reduce source water
Cryptosporidium levels.
(4)
Systems shall complete the
following actions to maintain the 0.5-log credit:
(i) Submit an annual watershed control
program status report to the Department. The annual watershed control program
status report must describe the system's implementation of the approved plan
and assess the adequacy of the plan to meet its goals. The report must explain
how the system is addressing any shortcomings in plan implementation, including
those previously identified by the Department or as the result of the watershed
survey conducted under subparagraph (ii). The report must also describe
significant changes that have occurred in the watershed since the last
watershed sanitary survey. If a system determines during implementation that
making a significant change to its approved watershed control program is
necessary, the system shall notify the Department prior to making any changes.
If a change is likely to reduce the level of source water protection, the
system shall also list in its notification the actions the system will take to
mitigate this effect.
(ii) Undergo
a watershed sanitary survey every 3 years for community water systems and every
5 years for noncommunity water systems and submit the survey report to the
Department. The survey must be conducted according to Department guidelines and
by persons the Department approves.
(A) The
watershed sanitary survey must meet the following criteria:
(I) Encompass the region identified in the
Department-approved watershed control plan as the area of influence.
(II) Assess the implementation of actions to
reduce source water Cryptosporidium levels.
(III) Identify any significant new sources of
Cryptosporidium.
(B) If the Department determines that
significant changes may have occurred in the watershed since the previous
watershed sanitary survey, systems shall undergo another watershed sanitary
survey by a date the Department requires, which may be earlier than the regular
date in this subparagraph.
(iii) The system shall make the watershed
control plan, annual status reports, and watershed sanitary survey reports
available to the public upon request. These documents must be in a plain
language style and include criteria by which to evaluate the success of the
program in achieving plan goals. The Department may approve systems to withhold
from the public portions of the annual status report, watershed control plan,
and watershed sanitary survey based on water supply security
considerations.
(5) If
the Department determines that a system is not carrying out the approved
watershed control plan, the Department may withdraw the watershed control
program treatment credit.
(c)
Alternative source.
(1) A system may conduct source water
monitoring that reflects a different intake location (either in the same source
or for an alternate source) or a different procedure for the timing or level of
withdrawal from the source (alternative source monitoring). If the Department
approves, a system may determine its bin classification under §
109.1203 based on the alternative
source monitoring results.
(2) If
systems conduct alternative source monitoring under paragraph (1), systems
shall also monitor their current plant intake concurrently as described in
§
109.1202 (relating to monitoring
requirements).
(3) Alternative
source monitoring under paragraph (1) must meet the requirements for source
monitoring to determine bin classification, as described in §
109.1202 and §
109.1206 (relating to reporting
and recordkeeping requirements). Systems shall report the alternative source
monitoring results to the Department, along with supporting information
documenting the operating conditions under which the samples were
collected.
(4) If a system
determines its bin classification under §
109.1203 using alternative source
monitoring results that reflect a different intake location or a different
procedure for managing the timing or level of withdrawal from the source, the
system shall relocate the intake or permanently adopt the withdrawal procedure,
as applicable, no later than the applicable treatment compliance date in §
109.1203(k)-(o).
(d)
Presedimentation. Systems will receive 0.5-log
Cryptosporidium treatment credit for a presedimentation basin
during any month the process meets the criteria in this subsection.
(1) The presedimentation basin must be in
continuous operation and must treat the entire plant flow taken from a surface
water or GUDI source.
(2) The
system shall continuously add a coagulant to the presedimentation
basin.
(3) The presedimentation
basin must achieve the performance criteria as follows:
(i) Demonstrates at least 0.5-log mean
reduction of influent turbidity. This reduction must be determined using daily
turbidity measurements in the presedimentation process influent and effluent
and must be calculated as follows: log10 (monthly mean of daily influent
turbidity)-log10 (monthly mean of daily effluent turbidity).
(ii) Comply with Department-approved
performance criteria that demonstrate at least 0.5-log mean removal of
micron-sized particulate material through the presedimentation
process.
(e)
2-stage lime softening. Systems receive an additional 0.5-log
Cryptosporidium treatment credit for a 2-stage lime softening
plant if chemical addition and hardness precipitation occur in two separate and
sequential softening stages prior to filtration. Both softening stages must
treat the entire plant flow taken from a surface water or GUDI
source.
(f)
Bank
filtration. Systems receive
Cryptosporidium treatment
credit for bank filtration that serves as pretreatment to a filtration plant by
meeting the criteria in this subsection. Systems using bank filtration when
they begin source water monitoring under §
109.1202(a) shall
collect samples as described in §
109.1202(n) and
are not eligible for this credit.
(1) Wells
with a groundwater flow path of at least 25 feet receive 0.5-log treatment
credit. Wells with a groundwater flow path of at least 50 feet receive 1.0-log
treatment credit. The groundwater flow path must be determined as specified in
paragraph (4).
(2) Only wells in
granular aquifers are eligible for treatment credit. Granular aquifers are
those comprised of sand, clay, silt, rock fragments, pebbles or larger
particles and minor cement. A system shall characterize the aquifer at the well
site to determine aquifer properties. Systems shall extract a core from the
aquifer and demonstrate that in at least 90% of the core length, grains less
than 1.0 mm in diameter constitute at least 10% of the core material.
(3) Only horizontal and vertical wells are
eligible for treatment credit.
(4)
For vertical wells, the groundwater flow path is the measured distance from the
edge of the surface water body under high flow conditions (determined by the
100 year floodplain elevation boundary or by the floodway, as defined in
Federal Emergency Management Agency flood hazard maps) to the well screen. For
horizontal wells, the groundwater flow path is the measured distance from the
bed of the river under normal flow conditions to the closest horizontal well
lateral screen.
(5) Systems shall
monitor each wellhead for turbidity at least once every 4 hours while the bank
filtration process is in operation. If monthly average turbidity levels, based
on daily maximum values in the well, exceed 1 NTU, the system shall report this
result to the Department and conduct an assessment within 30 days to determine
the cause of the high turbidity levels in the well. If the Department
determines that microbial removal has been compromised, the Department may
revoke treatment credit until the system implements corrective actions approved
by the Department to remediate the problem.
(6) Springs and infiltration galleries are
not eligible for treatment credit under this section, but are eligible for
credit under subsection (i).
(7)
The Department may approve
Cryptosporidium treatment credit
for bank filtration based on a demonstration of performance study that meets
the criteria in this paragraph. This treatment credit may be greater than
1.0-log and may be awarded to bank filtration that does not meet the criteria
in paragraphs (1)-(5).
(i) The study must
follow a Department-approved protocol and must involve the collection of data
on the removal of Cryptosporidium or a surrogate for
Cryptosporidium and related hydrogeologic and water quality
parameters during the full range of operating conditions.
(ii) The study must include sampling both
from the production well and from monitoring wells that are screened and
located along the shortest flow path between the surface water source and the
production well.
(g)
Combined filter
performance. Systems using conventional filtration treatment or direct
filtration treatment receive an additional 0.5-log
Cryptosporidium treatment credit during any month the system
meets the criteria in this subsection. Combined filter effluent (CFE) turbidity
must be less than or equal to 0.15 NTU in at least 95% of the measurements.
Turbidity must be measured as described in §
109.304(c)
(relating to analytical requirements).
(h)
Individual filter performance.
Systems using conventional filtration treatment or direct filtration
treatment will receive 0.5-log
Cryptosporidium treatment
credit, which can be in addition to the 0.5-log credit under subsection (g),
during any month the system meets the criteria in this subsection. Compliance
with these criteria must be based on individual filter turbidity monitoring as
described in §
109.301(1)(iii)
(relating to general monitoring requirements), as applicable.
(1) The filtered water turbidity for each
individual filter must be less than or equal to 0.15 NTU in at least 95% of the
measurements recorded each month.
(2) An individual filter may not have a
measured turbidity greater than 0.3 NTU in two consecutive measurements taken
15 minutes apart.
(3) A system that
has received treatment credit for individual filter performance and fails to
meet the requirements of paragraph (1) or (2) during any month does not receive
a treatment technique violation under §
109.1203(g) if
the Department determines the following:
(i)
The failure was due to unusual and short-term circumstances that could not
reasonably be prevented through optimizing treatment plant design, operation,
and maintenance.
(ii) The system
has experienced no more than two of these failures in any calendar
year.
(i)
Demonstration of performance. The Department may approve
Cryptosporidium treatment credit for drinking water treatment
processes based on a demonstration of performance study that meets the criteria
in this subsection. This treatment credit may be greater than or less than the
prescribed treatment credits in §
109.1203(e)-(h)
or subsection (d)-(f) and subsections (n)-(q) and may be awarded to treatment
processes that do not meet the criteria for the prescribed credits.
(1) Systems cannot receive the prescribed
treatment credit for any toolbox option in subsections (d)-(f) or (n)-(q) if
that toolbox option is included in a demonstration of performance study for
which treatment credit is awarded under this paragraph.
(2) The demonstration of performance study
must follow a Department-approved protocol and must demonstrate the level of
Cryptosporidium reduction the treatment process will achieve
under the full range of expected operating conditions for the system.
(3) Approval by the Department will be in
writing and may include monitoring and treatment performance criteria that the
system shall demonstrate and report on an ongoing basis to remain eligible for
the treatment credit. The Department may designate the criteria when necessary
to verify that the conditions under which the demonstration of performance
credit was approved are maintained during routine operation.
(j)
Bag and cartridge
filters. Systems receive
Cryptosporidium treatment
credit of up to 2.0-log for individual bag or cartridge filters and up to
2.5-log for bag or cartridge filters operated in series by meeting the criteria
in paragraphs (1)-(10). To be eligible for this credit, systems shall report
the results of challenge testing that meet the requirements of paragraphs
(2)-(9) to the Department. The filters must treat the entire plant flow taken
from a surface water or groundwater source under the direct influence of
surface water source.
(1) The
Cryptosporidium treatment credit awarded to bag or cartridge
filters will be based on the removal efficiency demonstrated during challenge
testing that is conducted according to the criteria in paragraphs (2)-(9). A
factor of safety equal to 1-log for individual bag or cartridge filters and
0.5-log for bag or cartridge filters in series must be applied to challenge
testing results to determine removal credit. Systems may use results from
challenge testing conducted prior to January 5, 2006, if the prior testing was
consistent with the criteria specified in paragraphs (2)-(9).
(2) Challenge 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 housings the system will use for removal of
Cryptosporidium. Bag or cartridge filters must be challenge
tested in the same configuration that the system will use, either as individual
filters or as a series configuration of filters.
(3) Challenge testing must be conducted using
Cryptosporidium or a surrogate that is removed no more
efficiently than Cryptosporidium. The microorganism or
surrogate used during challenge testing is referred to as the challenge
particulate. The concentration of the challenge particulate must be determined
using a method capable of discretely quantifying the specific microorganism or
surrogate used in the test; gross measurements such as turbidity may not be
used.
(4) The maximum feed water
concentration that can be used during a challenge test must be based on the
detection limit of the challenge particulate in the filtrate (that is, filtrate
detection limit) and must be calculated using the following equation:
Maximum Feed Concentration =1 x
104 x (Filtrate Detection Limit)
(5) Challenge testing must be conducted at
the maximum design flow rate for the filter as specified by the
manufacturer.
(6) Each filter
evaluated must be tested for a duration sufficient to reach 100% of the
terminal pressure drop, which establishes the maximum pressure drop under which
the filter may be used to comply with this subchapter.
(7) 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; and 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.
(8) Each filter tested must be
challenged with the challenge particulate during three periods over the
filtration cycle: within 2 hours of start-up of a new filter; when the pressure
drop is between 45 and 55% of the terminal pressure drop; and at the end of the
cycle after the pressure drop has reached 100% of the terminal pressure drop.
An LRV must be calculated for each of these challenge periods for each filter
tested. The LRV for the filter (LRVfilter) must be
assigned the value of the minimum LRV observed during the three challenge
periods for that filter.
(9) If
less than 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. If 20 or more filters are tested, the overall removal
efficiency for the filter product line must be set equal to the 10th percentile
of the set of LRVfilter values for the various filters
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 10th
percentile may be calculated using linear interpolation.
(10) 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 conducted and submitted to the Department.
(k)
Membrane
filtration.
(1) Cryptosporidium
treatment credit. Systems receive
Cryptosporidium treatment credit for membrane filtration that
meets the criteria of this paragraph. Membrane cartridge filters that meet the
definition of membrane filtration in §
109.1 (relating to definitions)
are eligible for this credit. The level of treatment credit a system receives
is equal to the lower of the values determined under the following:
(i) The removal efficiency demonstrated
during challenge testing conducted under the conditions in paragraph
(2).
(ii) The maximum removal
efficiency that can be verified through direct integrity testing used with the
membrane filtration process under the conditions in paragraph (3).
(2)
Challenge
testing. The membrane used by the system shall undergo challenge
testing to evaluate removal efficiency, and the system shall report the results
of challenge testing to the Department. Challenge testing must be conducted
according to the criteria in subparagraphs (i)-(vii). Systems may use data from
challenge testing conducted prior to January 5, 2006, if the prior testing was
consistent with the criteria in subparagraphs (i)-(vii).
(i) Challenge testing must be conducted on
either a full-scale membrane module, identical in material and construction to
the membrane modules used in the system's treatment facility, or a
smaller-scale membrane module, 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 that is removed
no more efficiently than Cryptosporidium oocysts. The organism
or surrogate used during challenge testing is referred to as the challenge
particulate. 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; gross
measurements such as turbidity may not be used.
(iii) The maximum feed water concentration
that can 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 x
106 x (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. Flux is defined as the throughput of a pressure driven membrane process
expressed as flow per unit of membrane area. Recovery is defined as the
volumetric % 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 (that is, 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 the
challenge test; Cf = the feed concentration measured
during the challenge test; and Cp = the filtrate
concentration measured during the challenge test. Equivalent units must be used
for the feed and filtrate concentrations. If the challenge particulate is not
detected in the filtrate, the term Cp is 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 removal efficiency
of a membrane filtration process demonstrated during challenge testing must be
expressed as a log removal value (LRVC-Test). If less
than 20 modules are tested, then LRVC-Test is equal to
the lowest of the representative LRVs among the modules tested. If 20 or more
modules are tested, then LRVC-Test is equal to the 10th
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 10th percentile may be calculated using
linear interpolation.
(vii) The
challenge test must establish a quality control release value (QCRV) for a
nondestructive performance test that demonstrates the
Cryptosporidium removal capability of the membrane filtration
module. This 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. 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 Department.
(3)
Direct integrity testing
. Systems shall conduct direct integrity testing in a manner that demonstrates
a removal efficiency equal to or greater than the removal credit awarded to the
membrane filtration process and meets the requirements described in
subparagraphs (i)-(vi). A direct integrity test is defined as a physical test
applied to a membrane unit to identify and isolate integrity breaches (that is,
one or more leaks that could result in contamination of the filtrate).
(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 3 micrometers 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 Department, 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 clause (A) or (B) as applicable to the type of direct
integrity test the system uses.
(A) 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, and VCF = volumetric concentration factor. The
volumetric concentration factor is the ratio of the suspended solids
concentration on the high pressure side of the membrane relative to that in the
feed water.
(B) 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; and Cp =
the filtrate concentration of the marker from an integral membrane unit.
(iv) Systems
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 Department.
(v) If the result of a direct integrity test
exceeds the control limit established under subparagraph (iv), the system shall
remove the membrane unit from service. Systems shall conduct a direct integrity
test to verify any repairs, and may return the membrane unit to service only if
the direct integrity test is within the established control limit.
(vi) Systems shall conduct direct integrity
testing on each membrane unit at a frequency of at least once each day that the
membrane unit is in operation. The Department may approve less frequent
testing, based on demonstrated process reliability, the use of multiple
barriers effective for Cryptosporidium, or reliable process
safeguards.
(4)
Indirect integrity monitoring. Systems shall conduct
continuous indirect integrity monitoring on each membrane unit according to the
criteria in subparagraphs (i)-(v). Indirect integrity monitoring is defined as
monitoring some aspect of filtrate water quality that is indicative of the
removal of particulate matter. A system that implements continuous direct
integrity testing of membrane units in accordance with the criteria in
subparagraphs (i)-(v) is not subject to the requirements for continuous
indirect integrity monitoring. Systems shall submit a monthly report to the
Department summarizing all continuous indirect integrity monitoring results
triggering direct integrity testing and the corrective action that was taken in
each case.
(i) Unless the Department approves
an alternative parameter, continuous indirect integrity monitoring must include
continuous filtrate turbidity monitoring.
(ii) Continuous monitoring must be conducted
at least once every 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 0.15 NTU
for a period greater than 15 minutes (that is, two consecutive 15-minute
readings above 0.15 NTU), direct integrity testing must immediately be
performed on the associated membrane unit as specified in paragraph
(3)(i)-(v).
(v) If indirect
integrity monitoring includes a Department-approved alternative parameter and
if the alternative parameter exceeds a Department-approved control limit for a
period greater than 15 minutes, direct integrity testing shall immediately be
performed on the associated membrane units as specified in paragraph
(3)(i)-(v).
(l)
Second stage filtration. Systems receive 0.5-log
Cryptosporidium treatment credit for a separate second stage
of filtration that consists of sand, dual media, GAC or other fine grain media
following granular media filtration if approved by the Department. To be
eligible for this credit, the first stage of filtration must be preceded by a
coagulation step and both filtration stages must treat the entire plant flow
taken from a surface water or GUDI source. A cap, such as GAC, on a single
stage of filtration is not eligible for this credit. The Department will
approve the treatment credit based on an assessment of the design
characteristics of the filtration process.
(m)
Slow sand filtration (as
secondary filter). Systems are eligible to receive 2.5-log
Cryptosporidium treatment credit for a slow sand filtration
process that follows a separate stage of filtration if both filtration stages
treat entire plant flow taken from a surface water or GUDI source and no
disinfectant residual is present in the influent water to the slow sand
filtration process. The Department will approve the treatment credit based on
an assessment of the design characteristics of the filtration process. This
subsection does not apply to treatment credit awarded to slow sand filtration
used as a primary filtration process.
(n)
Inactivation toolbox
components. Calculation of CT values.
(1) Systems with treatment credit for
chlorine dioxide or ozone under subsection (o) or (p) must calculate CT at
least once each day, with both C and T measured during peak hourly flow as
specified in § 109.304(c) and
40 CFR
141.74(b)(3) (relating to
analytical and monitoring requirements).
(2) Systems with several disinfection
segments in sequence may calculate CT for each segment, where a disinfection
segment is defined as a treatment unit process with a measurable disinfectant
residual level and a liquid volume. Under this approach, systems shall add the
Cryptosporidium CT values in each segment to determine the
total CT for the treatment plant.
(o)
Chlorine dioxide.
Systems are eligible to receive the Cryptosporidium treatment
credit listed in Table 1, CT Values (mg * min/L) for
Cryptosporidium Inactivation by Chlorine Dioxide, contained in
Appendix A to Subchapter L by meeting the corresponding chlorine dioxide CT
value for the applicable water temperature, as described in subsection
(n).
(p)
Ozone.
Systems receive the Cryptosporidium treatment credit listed in
Table 2, CT Values (mg * min/L) for Cryptosporidium
Inactivation by Ozone, contained in Appendix A to Subchapter L, by meeting the
corresponding ozone CT values for the applicable water temperature, as
described in subsection (n).
(q)
Ultraviolet light. Systems receive
Cryptosporidium,
Giardia lamblia and virus
treatment credits for ultraviolet (UV) light reactors by achieving the
corresponding UV dose values shown in Table 3, UV Dose for
Cryptosporidium,
Giardia lamblia and Virus
Inactivation, contained in Appendix A to Subchapter L, as described in
paragraph (1). Systems shall validate and monitor UV reactors as described in
paragraphs (2) and (3) to demonstrate that they are achieving a particular UV
dose value for treatment credit.
(1)
UV dose table. The treatment credits listed in Table 3 are for
UV light at a wavelength of 254 nm as produced by a low pressure mercury vapor
lamp. To receive treatment credit for other lamp types, systems shall
demonstrate an equivalent germicidal dose through reactor validation testing,
as described in paragraph (2). The UV dose values in this table are applicable
only to post-filter applications of UV in filtered systems.
(2)
Reactor validation
testing. Systems shall use UV reactors that have undergone validation
testing, conducted by a party acceptable to the Department, to determine the
operating conditions under which the reactor delivers the UV dose required in
paragraph (1) (that is, validated operating conditions). These operating
conditions must include flow rate, UV intensity as measured by a UV sensor and
UV lamp status.
(i) When determining validated
operating conditions, systems shall account for the following factors:
(A) UV absorbance of the water.
(B) Lamp fouling and aging.
(C) Measurement uncertainty of on-line
sensors.
(D) UV dose distributions
arising from the velocity profiles through the reactor.
(E) Failure of UV lamps or other critical
system components.
(F) Inlet and
outlet piping or channel configurations of the UV reactor.
(ii) Validation testing must include the
following: Full scale testing of a reactor that conforms uniformly to the UV
reactors used by the system and inactivation of a test microorganism whose dose
response characteristics have been quantified with a low pressure mercury vapor
lamp.
(iii) The Department may
accept alternative validation testing approaches, if these approaches are first
approved by the EPA.
(3)
Reactor monitoring.
(i)
Systems shall monitor their UV reactors to determine if the reactors are
operating within validated conditions, as determined under paragraph (2). This
monitoring must include UV intensity as measured by a UV sensor, flow rate,
lamp status, and other parameters the Department designates based on UV reactor
operation. Systems shall verify the calibration of UV sensors and shall
recalibrate sensors in accordance with a protocol the Department
approves.
(ii) To receive treatment
credit for UV light, systems shall treat at least 95% of the water delivered to
the public during each month by UV reactors operating within validated
conditions for the required UV dose, as described in paragraphs (1) and (2).
Systems shall demonstrate compliance with this condition by the monitoring
required under subparagraph (i).