10 CSR 60-4.094 - Disinfectant Residuals, Disinfection Byproduct Precursors and the Stage 2 Disinfectants/Disinfection Byproducts Rule
(1) Stage 2 Disinfectants/Disinfection
Byproducts (D/DBP) Rule General Requirements.
(A) The requirements of this rule constitute
national primary drinking water regulations. This rule establishes monitoring
and other requirements for achieving compliance with maximum contaminant levels
based on locational running annual averages (LRAA) for total trihalomethanes
(TTHM) and haloacetic acids five (HAA5), and for achieving compliance with
maximum residual disinfectant residuals for chlorine and chloramine for certain
consecutive systems.
(B)
Applicability. This rule applies to community water systems
and nontransient noncommunity water systems that use a primary or residual
disinfectant other than ultraviolet light or deliver water that has been
treated with a primary or residual disinfectant other than ultraviolet
light.
(C) Community water systems
and nontransient noncommunity water systems must comply with maximum residual
disinfectant levels (MRDLs), monitoring and compliance requirements of this
rule, and the MCLs of 0.080 mg/L for total triahalomethanes (TTHM), 0.060 mg/L
for haloacetic acids (five) (HAA5), 0.010 mg/L for bromate, and 1.0 mg/L for
chlorite.
(2) Monitoring
Requirements.
(A) Disinfectant Residuals,
Chlorite, and Bromate Monitoring Requirements.
1. Chlorine and chloramines.
A. Routine monitoring. Community and
nontransient noncommunity water systems must measure the residual disinfectant
level at the same points in the distribution system and at the same time as
total coliforms are sampled, as specified in 10 CSR 604.022. Systems using
surface water or ground water under the direct influence of surface water may
use the results of residual disinfectant concentration sampling conducted under
10 CSR
60-4.080(3) and 10 CSR 604.055(4), in
lieu of taking separate samples.
B.
Reduced monitoring. Monitoring may not be reduced.
2. Chlorine dioxide.
A. Routine monitoring. Community,
nontransient noncommunity, and transient noncommunity water systems that use
chlorine dioxide for disinfection or oxidation must take daily samples at the
entrance to the distribution system. For any daily sample that detects chlorine
dioxide, the system must take additional samples in the distribution system the
following day in addition to the sample required at the entrance to the
distribution system.
B. Additional
monitoring. On each day following a routine sample monitoring result that
detects chlorine dioxide, the system is required to take three (3) chlorine
dioxide distribution system samples as close to the first customer as possible,
at intervals of at least six (6) hours. If chloramines are used to maintain a
disinfectant residual in the distribution system, or if chlorine is used to
maintain a disinfectant residual in the distribution system and there are no
disinfection addition points after the entrance to the distribution system
(that is, no booster chlorination), the system must take three (3) samples as
close to the first customer as possible, at intervals of at least six (6)
hours. If chlorine is used to maintain a disinfectant residual in the
distribution system and there are one (1) or more disinfection addition points
after the entrance to the distribution system (that is, booster chlorination),
the system must take one (1) sample at each of the following locations: as
close to the first customer as possible; in a location representative of
average residence time; and as close to the end of the distribution system as
possible (reflecting maximum residence time in the distribution
system).
C. Reduced monitoring.
Chlorine dioxide monitoring may not be reduced.
3. Chlorite.
A. Routine monitoring. Community and
nontransient noncommunity water systems using chlorine dioxide, for
disinfection or oxidation, must conduct monitoring for chlorite.
(I) Daily Monitoring. Systems must take daily
samples at the entrance to the distribution system. For any daily sample that
exceeds the chlorite MCL, the system must take additional samples in the
distribution system the following day at the following locations: near the
first customer; at a location representative of average residence time; and at
a location reflecting maximum residence time in the distribution system, in
addition to the sample required at the entrance to the distribution
system.
(II) Monthly monitoring.
Systems must take a three (3)-sample set each month in the distribution system.
The system must take one (1) sample at each of the following locations: near
the first customer; at a location representative of average residence time; and
at a location reflecting maximum residence time in the distribution system. Any
additional routine sampling must be conducted in the same manner (as three
(3)-sample sets, at the specified locations). The system may use the results of
additional monitoring conducted under the following subparagraph (2)(A)3.B. to
meet the requirement for monthly monitoring.
B. Additional monitoring. On each day
following a routine sample monitoring result that exceeds the chlorite MCL at
the entrance to the distribution system, the system is required to take three
(3) chlorite distribution system samples at the following locations: as close
to the first customer as possible, in a location representative of average
residence time, and as close to the end of the distribution system as possible
(reflecting maximum residence time in the distribution system).
C. Reduced monitoring.
(I) Chlorite monitoring at the entrance to
the distribution system required by part (2)(A)3.A.(I) of this rule may not be
reduced.
(II) Chlorite monitoring
in the distribution system required by part (2)(A)3.A.(II) of this rule may be
reduced to one (1) three (3)-sample set per quarter after one (1) year of
monitoring where no individual chlorite sample taken in the distribution system
under part (2)(A)3.A.(II) of this rule has exceeded the chlorite MCL and the
system has not been required to conduct monitoring under subparagraph
(2)(A)3.B. of this rule. The system may remain on the reduced monitoring
schedule until either any of the three (3) individual chlorite samples taken
quarterly in the distribution system under part (2)(A)3.A.(II) of this rule
exceeds the chlorite MCL or the system is required to conduct monitoring under
subparagraph (2)(A)3.B. of this rule, at which time the system must revert to
routine monitoring.
4. Bromate.
A. Routine monitoring. Community and
nontransient noncommunity systems using ozone for disinfection or oxidation
must take one (1) sample per month for each treatment plant in the system using
ozone. Systems must take samples monthly at the entrance to the distribution
system while the ozonation system is operating under normal
conditions.
B. Reduced monitoring.
A system required to analyze for bromate may reduce monitoring from monthly to
quarterly, if the system's running annual average bromate concentration is less
than or equal to 0.0025 mg/L based on monthly bromate measurements for the most
recent four (4) quarters, with samples analyzed using Method 317.0 Revision
2.0, 326.0, or 321.8. If a system has qualified for reduced bromate monitoring,
that system may remain on reduced monitoring as long as the running annual
average of quarterly bromate samples is <=0.0025 mg/L based on samples
analyzed using Method 317.0 Revision 2.0, 326.0, or 321.8. If the running
annual average bromate concentration is >0.0025 mg/L, the system must resume
routine monitoring required by subparagraph (2)(A)4.A. of this rule.
(B) Disinfection
Byproduct Precursors (DBPP) Monitoring Requirements.
1. Total Organic Carbon (TOC).
A. Routine Monitoring. Systems using surface
water or ground water under the direct influence of surface water and using
conventional filtration treatment must monitor each treatment plant for total
organic carbon (TOC) no later than the point of combined filter effluent
turbidity monitoring and representative of the treated water. These systems
must also monitor for TOC in the source water prior to any treatment at the
same time as monitoring for TOC in the treated water. These samples (source
water and treated water) are referred to as paired samples. At the same time as
the source water sample is taken, all systems must monitor for alkalinity in
the source water prior to any treatment. Systems must take one (1) paired
sample and one (1) source water alkalinity sample per month per plant at a time
representative of normal operating conditions and influent water
quality.
B. Reduced monitoring.
Systems using surface water or ground water under the direct influence of
surface water with an average treated water TOC of less than 2.0 mg/L for two
(2) consecutive years, or less than 1.0 mg/L for one (1) year, may reduce
monitoring for both TOC and alkalinity to one (1) paired sample and one (1)
source water alkalinity sample per plant per quarter. The system must revert to
routine monitoring in the month following the quarter when the annual average
treated water TOC greater than or equal to 2.0 mg/L.
2. Bromide. Systems required to analyze for
bromate may reduce bromate monitoring from monthly to once per quarter, if the
system demonstrates that the average source water bromide concentration is less
than 0.05 mg/L based upon representative monthly measurements for one (1) year.
The system must continue bromide monitoring to remain on reduced bromate
monitoring.
(C) Total
Trihalomethane and Haloacetic Acid Monitoring Requirements.
1. General Requirements.
A. Undisinfected systems that begins using a
disinfectant other than ultraviolet (UV) light must consult with the department
to identify compliance monitoring locations for this rule. Systems must then
develop a monitoring plan that includes those monitoring locations.
B. Stage 2 D/DBP Compliance Monitoring Plan.
(I) Developing and implementing a monitoring
plan. The system must develop and implement a monitoring plan to be kept on
file for department and public review. Unless otherwise directed by the
department, the monitoring plan must contain the following elements and be
complete no later than the date initial monitoring under this rule is
conducted:
(a) Monitoring locations;
(b) Monitoring dates;
(c) Compliance calculation procedures;
and
(d) Monitoring plans for any
other systems in the combined distribution system if the department has reduced
monitoring requirements.
(II) The system must identify which locations
to use for Stage 2 D/DBP rule compliance monitoring by alternating selection of
locations representing high TTHM levels and high HAA5 levels until the required
number of Stage 2 D/DBP rule compliance monitoring locations have been
identified.
(III) The system must
submit a copy of the monitoring plan to the department prior to the date the
system conducts the initial monitoring under this rule.
(IV) A system may revise the monitoring plan
to reflect changes in treatment, distribution system operations and layout
(including new service areas), or other factors that may affect TTHM or HAA5
formation, or for department-approved reasons, after consultation with the
department regarding the need for changes and the appropriateness of changes.
If the system changes monitoring locations, the system must replace existing
compliance monitoring locations with the lowest LRAA with new locations that
reflect the current distribution system locations with expected high TTHM or
HAA5 levels. The department may also require modifications in the system's
monitoring plan. The system must submit a copy of the modified monitoring plan
to the department prior to the date the system is required to comply with the
revised monitoring plan.
C. Monitoring must begin at the locations and
months the system has recommended in the Stage 2 D/DBP Compliance Monitoring
Plan unless the department requires other locations or additional locations
after its review.
D. Analytical
methods. The system must use an approved method listed in
10 CSR
60-5.010 for TTHM and HAA5 analyses. Analyses must be
conducted by laboratories that have received certification by Environmental
Protection Agency (EPA) or the department as specified in 10 CSR
605.020.
E. Additional Requirements
for Consecutive Systems. If the system is a consecutive system that does not
add a disinfectant but delivers water that has been treated with a primary or
residual disinfectant other than ultraviolet light, the system must comply with
analytical and monitoring requirements for chlorine and chloramines in 10 CSR
605.010 and 10 CSR
60-4.055(4)(E), the compliance
requirements in 10 CSR
60-4.094(3)(B.) 1. and report
monitoring results under
10 CSR
60-7.010(5)(B).
Stage 2 D/DBP Routine Monitoring
Click here to view image
1 All systems must monitor during month of highest DBP concentrations.
2 Systems on quarterly monitoring must take dual sample sets every 90 days at each monitoring location, except for surface water systems or ground water under the direct influence of surface water serving 500-3,300. Groundwater systems serving 500-9,999 on annual monitoring must take dual sample sets at each monitoring location. All other systems on annual monitoring and surface water systems or ground water under the direct influence of surface water serving 500-3,300 are required to take individual TTHM and HAA5 samples (instead of a dual sample set) at the location with the highest TTHM and HAA5 concentrations, respectively. For systems serving fewer than five hundred (500) people, one (1) location with a dual sample set per monitoring period is needed if the highest TTHM and HAA5 concentrations occur at the same location.
2. Reduced Monitoring.
A. Monitoring requirements for source water
TOC. In order to qualify for reduced monitoring for TTHM and HAA5, surface
water and ground water under the direct influence of surface water (GWUDISW)
systems not monitoring under the TOC reduced monitoring provisions, must take
monthly TOC samples every thirty (30) days at a location prior to any
treatment. Once qualified for reduced monitoring for TTHM and HAA5, a system
may reduce source water TOC monitoring to quarterly TOC samples taken every
ninety (90) days at a location prior to any treatment.
B. The system may reduce monitoring any time
the LRAA is <=0.040 mg/L for TTHM and <=0.030 mg/L for HAA5 at all
monitoring locations. In addition, the source water annual average TOC level,
before any treatment, must be <=4.0 mg/L at each treatment plant treating
surface water or ground water under the direct influence of surface water.
Stage 2 D/DBP Reduced Monitoring
|
Source water type |
Population size category |
Monitoring Frequency1 |
Distribution system monitoring location per monitoring period |
|
Surface water system or ground water under the direct influence of surface water: |
<500 500-3,300 |
.......... Per year |
Monitoring may not be reduced. 1 TTHM and 1 HAA5 sample: one at the location and during the quarter with the highest TTHM single measurement; one at the location and during the quarter with the highest HAA5 single measurement; and 1 dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter. |
|
3,301-9,999 |
Per year |
2 dual sample sets: one at the location and during the quarter with the highest TTHM single measurement; and one at the location and during the quarter with the highest HAA5 single measurement. |
|
|
10,000-49,999 |
Per quarter |
2 dual sample sets at the locations with the highest TTHM and highest HAA5 LRAAs. |
|
|
50,000-249,999 |
Per quarter |
4 dual sample sets-at the locations with the two highest TTHM and two highest HAA5 LRAAs. |
|
|
250,000-999,999 |
Per quarter |
6 dual sample sets-at the locations with the three highest TTHM and three highest HAA5 LRAAs. |
|
|
1,000,000-4,999,999 |
Per quarter |
8 dual sample sets-at the locations with the four highest TTHM and four highest HAA5 LRAAs. |
|
|
>= 5,000,000 |
Per quarter |
10 dual sample sets-at the locations with the five highest TTHM and five highest HAA5 LRAAs. |
|
|
Ground water: |
<500 |
Every third year |
1 TTHM and 1 HAA5 sample: one at the location and during the quarter with the highest TTHM single measurement; one at the location and during the quarter with the highest HAA5 single measurement; and 1 dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter. |
|
500-9,999 |
Per year |
1 TTHM and 1 HAA5 sample: one at the location and during the quarter with the highest TTHM single measurement; one at the location and during the quarter with the highest HAA5 single measurement; and 1 dual sample set per year if the highest TTHM and HAA5 measurements occurred at the same location and quarter. |
|
|
10,000-99,999 |
Per year |
2 dual sample sets: one at the location and during the quarter with the highest TTHM single measurement; and one at the location and during the quarter with the highest HAA5 single measurement. |
|
|
100,000-499,999 |
Per quarter |
2 dual sample sets; at the locations with the highest TTHM and highest HAA5 LRAAs. |
|
|
>= 500,000 |
Per quarter |
4 dual sample sets at the locations with the two highest TTHM and two highest HAA5 LRAAs. |
1 Systems on quarterly monitoring must take dual sample sets every 90 days.
C. The system may remain on reduced
monitoring as long as the TTHM LRAA <=0.040 mg/L and the HAA5 LRAA
<=0.030 mg/L at each monitoring location (for systems with quarterly reduced
monitoring) or each TTHM sample <=0.060 mg/L and each HAA5 sample <=0.045
mg/L (for systems with annual or less frequent monitoring). In addition, the
source water annual average TOC level, before any treatment, must be <=4.0
mg/L at each treatment plant treating surface water or ground water under the
direct influence of surface water.
D. If the LRAA based on quarterly monitoring
at any monitoring location exceeds either 0.040 mg/L for TTHM or 0.030 mg/L for
HAA5 or if the annual (or less frequent) sample at any location exceeds either
0.060 mg/L for TTHM or 0.045 mg/L for HAA5, or if the source water annual
average TOC level, before any treatment, >4.0 mg/L at any treatment plant
treating surface water or ground water under the direct influence of surface
water, the system must resume routine monitoring under section
10 CSR
60-4.094(2)(C) 2. or begin increased
monitoring if paragraph
10 CSR
60-4.094(2)(C) 4. applies.
E. The department may return the system to
routine monitoring at the department's discretion.
3. Increased Monitoring.
A. If the system is required to monitor at a
particular location annually or less frequently than annually under routine or
reduced monitoring of this rule, the system must increase monitoring to dual
sample sets once per quarter (taken every ninety (90) days) at all locations if
a TTHM sample is >0.080 mg/L or an HAA5 sample is >0.060 mg/L at any
location.
B. The system is in
violation of the MCL when the LRAA exceeds the Stage 2 D/DBP rule MCLs in
subparagraph 10 CSR
60-4.094(3)(D) 3.A., calculated based
on four (4) consecutive quarters of monitoring (or the LRAA calculated based on
fewer than four (4) quarters of data if the MCL would be exceeded regardless of
the monitoring results of subsequent quarters). The system is in violation of
the monitoring requirements for each quarter that a monitoring result would be
used in calculating an LRAA if the system fails to monitor.
C. The system may return to routine
monitoring once the system has conducted increased monitoring for at least four
(4) consecutive quarters and the LRAA for every monitoring location is
<=0.060 mg/L for TTHM and <=0.045 mg/L for HAA5.
(3) Compliance
Requirements.
(A) General Requirements.
1. Where compliance is based on a locational
running annual average (LRAA) or running annual average (RAA) of monthly or
quarterly samples or averages and the system fails to monitor for TTHM, HAA5,
or bromate, this failure to monitor will be treated as a monitoring violation
for the entire period covered by the annual average.
2. Where compliance is based on a running
annual average of monthly or quarterly samples or averages and the system's
failure to monitor makes it impossible to determine compliance with MRDLs for
chlorine and chloramines, this failure to monitor will be treated as a
monitoring violation for the entire period covered by the annual
average.
3. All samples taken and
analyzed under the provisions of this rule must be included in determining
compliance, even if that number is greater than the minimum required.
4. If, during the first year of monitoring,
any individual quarter's average will cause the running annual average of that
system to exceed the MCL, the system is out of compliance at the end of that
quarter.
5. Systems required to
monitor quarterly. To comply with MCLs in paragraph
10 CSR
60-4.094(2)(C) 1.the system must
calculate LRAAs for TTHM and HAA5 using monitoring results collected under this
rule and determine that each LRAA does not exceed the MCL. If the system fails
to complete four (4) consecutive quarters of monitoring, the system must
calculate compliance with the MCL based on the average of the available data
from the most recent four (4) quarters. If the system takes more than one (1)
sample per quarter at a monitoring location, the system must average all
samples taken in the quarter at that location to determine a quarterly average
to be used in the LRAA calculation.
6. Systems required to monitor yearly or less
frequently. To determine compliance with the Stage 2 D/DBP MCLs in subparagraph
10 CSR
60-4.094(3)(D) 3.A., the system must
determine that each sample taken is less than the MCL. If any sample exceeds
the MCL, the system must comply with the requirements of increased monitoring
of this rule. If no sample exceeds the MCL, the sample result for each
monitoring location is considered the LRAA for that monitoring
location.
7. Violation. If a system
fails to monitor, the system is in violation of the monitoring requirements for
each quarter or monitoring period that a monitoring result would be used in
calculating a LRAA for TTHM and HAA5 or RAA for bromate or
chlorite.
(B)
Disinfectant Residuals, Chlorite, and Bromate.
1. Chlorine and chloramines.
A. Compliance must be based on a running
annual arithmetic average, computed quarterly, of monthly averages of all
samples collected by the system under paragraph (2)(A)1. of this rule. If the
average covering any consecutive four (4)-quarter period exceeds the MRDL, the
system is in violation of the MRDL and must notify the public pursuant to
10 CSR
60-8.010, in addition to reporting to the department
pursuant to 10 CSR 60-7.010.
B. In cases where systems switch between the
use of chlorine and chloramines for residual disinfection during the year,
compliance must be determined by including together all monitoring results of
both chlorine and chloramines in calculating compliance. Reports submitted
pursuant to 10 CSR
60-7.010(5) must clearly indicate
which residual disinfectant was analyzed for each sample.
2. Chlorine dioxide.
A. Acute violations. Compliance must be based
on consecutive daily samples collected by the system under subparagraph
(2)(A)2.A. of this rule. If any daily sample taken at the entrance to the
distribution system exceeds the MRDL, and on the following day one (1) (or
more) of the three (3) samples taken in the distribution system exceed the
MRDL, the system is in violation of the MRDL and must take immediate corrective
action to lower the level of chlorine dioxide below the MRDL and must notify
the public pursuant to the procedures for acute health risks in
10 CSR
60-8.010(2), in addition to reporting
to the department pursuant to
10 CSR
60-7.010. Failure to take samples in the distribution
system the day following an exceedance of the chlorine dioxide MRDL at the
entrance to the distribution system will also be considered an MRDL violation
and the system must notify the public of the violation in accordance with the
provisions for acute violations under
10 CSR
60-8.010(2), in addition to reporting
to the department pursuant to
10 CSR
60-7.010.
B. Nonacute violations. Compliance must be
based on consecutive daily samples collected by the system in compliance with
this rule.
(I) If any two (2) consecutive
daily samples taken at the entrance to the distribution system detect chlorine
dioxide, the system must take corrective action to lower the chlorine dioxide
level.
(II) If any two (2)
consecutive daily samples taken at the entrance to the distribution system
exceed the MRDL and all distribution system samples taken are below the MRDL,
the system is in violation of the MRDL and must take corrective action to lower
the level of chlorine dioxide below the MRDL at the point of sampling and
notify the public pursuant to the procedures for nonacute health risks in
10 CSR
60-8.010(3), in addition to reporting
to the department pursuant to
10 CSR
60-7.010. Failure to monitor at the entrance to the
distribution system the day following an exceedance of the chlorine dioxide
MRDL at the entrance to the distribution system is also an MRDL violation and
the system must notify the public of the violation in accordance with the
provisions for nonacute violations in 10 CSR 608.010(3), in addition to
reporting to the department pursuant to
10 CSR
60-7.010.
(C) Disinfection Byproduct Precursors (DBPP).
1. Systems using surface water or ground
water under the direct influence of surface water and using conventional
filtration treatment must operate with enhanced coagulation or enhanced
softening to achieve the TOC percent removal levels specified in this rule
unless the system meets at least one (1) of the alternative compliance criteria
listed here. These systems must still comply with monitoring and compliance
requirements of this rule. The alternative compliance criteria for enhanced
coagulation and enhanced softening are:
A. The
system's source water TOC level, measured according to 10 CSR 605.010, is less
than 2.0 mg/L, calculated quarterly as a running annual average;
B. The system's treated water TOC level,
measured according to 10 CSR 605.010, is less than 2.0 mg/L, calculated
quarterly as a running annual average;
C. The system's source water TOC level,
measured according to 10 CSR 605.010, is less than 4.0 mg/L, calculated
quarterly as a running annual average; the source water alkalinity, measured
according to 10 CSR 60-5.010, is greater than
sixty (60) mg/L (as CaCO3), calculated quarterly as a
running annual average; and either the TTHM and HAA5 running annual averages
are no greater than 0.040 mg/L and 0.030 mg/L, respectively; or prior to the
effective date for compliance with this rule, the system has made a clear and
irrevocable financial commitment not later than the effective date for
compliance with this rule to use technologies that will limit the levels of
TTHMs and HAA5 to no more than 0.040 mg/L and 0.030 mg/L, respectively. Systems
must submit evidence of a clear and irrevocable financial commitment, in
addition to a schedule containing milestones and periodic progress reports for
installation and operation of appropriate technologies, to the department for
approval not later than the effective date for compliance with this rule. These
technologies must be installed and operating not later than June 30, 2005.
Failure to install and operate these technologies by the date in the approved
schedule will constitute a violation;
D. The TTHM and HAA5 running annual averages
are no greater than 0.040 mg/L and 0.030 mg/L, respectively, and the system
uses only chlorine for primary disinfection and maintenance of a residual in
the distribution system;
E. The
system's source water SUVA, prior to any treatment and measured monthly
according to 10 CSR 60-5.010, is less than or
equal to 2.0 L/mg-m, calculated quarterly as a running annual average. SUVA
refers to Specific Ultraviolet Absorption at two hundred fifty-four nanometers
(254 nm), an indicator of the humic content of water. It is a calculated
parameter obtained by dividing a sample's ultraviolet absorption at a
wavelength of 254 nm (UV254) (in
m=1) by its concentration of dissolved organic
carbon (DOC) (in mg/L); and
F. The
system's finished water SUVA, measured monthly according to 10 CSR 605.010, is
less than or equal to 2.0 L/mg-m, calculated quarterly as a running annual
average.
2. Additional
alternative compliance criteria for softening systems. Systems practicing
enhanced softening that cannot achieve the Step 1 TOC removals may use the
alternative compliance criteria listed here in lieu of complying with paragraph
(3)(C)3. of this rule. Systems must still comply with monitoring and compliance
requirements of this rule.
A. Softening that
results in lowering the treated water alkalinity to less than sixty (60) mg/L
(as CaCO3), measured monthly according to
10 CSR
60-5.010 and calculated quarterly as a running annual
average.
B. Softening that results
in removing at least ten (10) mg/L of magnesium hardness (as
CaCO3), measured monthly according to
10 CSR
60-5.010 and calculated quarterly as an annual running
average.
3. Enhanced
coagulation and enhanced softening performance requirements.
A. Systems must achieve the percent reduction
of TOC specified in Table 1 between the source water and the combined filter
effluent, unless the department approves a system's request for alternate
minimum TOC removal (Step 2) requirements. Systems may begin monitoring to
determine whether Step 1 TOC removals can be met twelve (12) months prior to
the compliance date for the system. This monitoring is not required and failure
to monitor during this period is not a violation. However, any system that does
not monitor during this period, and then determines in the first twelve (12)
months after the compliance date that it is not able to meet the Step 1
requirements and must therefore apply for alternate minimum TOC removal (Step
2) requirements, is not eligible for retroactive approval of alternate minimum
TOC removal (Step 2) requirements and is in violation. Systems may apply for
alternate minimum TOC removal (Step 2) requirements any time after the
compliance date. For systems required to meet Step 1 TOC removals, if the value
calculated under part (3)(C)4.A.(IV) of this rule is less than 1.00, the system
is in violation of the treatment technique requirements and must notify the
public pursuant to 10 CSR 60-8.010 in addition to
reporting to the department pursuant to
10 CSR
60-7.010.
B. Required Step 1 TOC reductions, indicated
in the following table, are based upon specified source water parameters
measured in accordance with
10 CSR
60-5.010. Systems practicing softening are required to
meet the Step 1 TOC reductions in the far right column (Source water alkalinity
>120 mg/L) for the specified source water TOC.
Table 1: Required Step 1 TOC Reduction
|
Step 1 Required Removal of TOC by Enhanced Coagulation and Enhanced Softening for Surface Water and GWUDISW Systems Using Conventional Treatment1,2 |
|||
|
Source water TOC, mg/L |
Source water alkalinity, mg/L as CaCO3 |
||
|
0-60 |
>60-120 |
>1203 |
|
|
>2.0-4.0 |
35.0% |
25.0% |
15.0% |
|
>4.0-8.0 |
45.0% |
35.0% |
25.0% |
|
>8.0 |
50.0% |
40.0% |
30.0% |
1Systems meeting at least one (1) of the conditions in paragraph (3)(C)1. of this rule are not required to operate with enhanced coagulation.
2Softening systems meeting one (1) of the alternative compliance criteria in paragraph (3)(C)1. of this rule are not required to operate with enhanced softening.
3Systems practicing softening must meet the TOC removal requirements in this column.
C. Conventional treatment systems using
surface water or ground water under the direct influence of surface water that
cannot achieve the Step 1 TOC removals due to water quality parameters or
operational constraints must apply to the department, within three (3) months
of failure to achieve the Step 1 TOC removals, for approval of alternative
minimum TOC removal (Step 2) requirements submitted by the system. If the
department approves the alternative minimum TOC removal (Step 2) requirements,
the department may make those requirements retroactive for the purposes of
determining compliance. Until the department approves the alternate minimum TOC
removal (Step 2) requirements, the system must meet the Step 1 TOC removals.
D. Alternate minimum TOC removal
(Step 2) requirements. Applications made to the department by enhanced
coagulation systems for approval of alternative minimum TOC removal (Step 2)
requirements under subparagraph (3)(C)3.C. of this rule must include, as a
minimum, results of bench- or pilot-scale testing conducted under this
subparagraph (3)(C)3.D. and used to determine the alternate enhanced
coagulation level.
(I) Alternate enhanced
coagulation level is defined as coagulation at a coagulant dose and pH as
determined by the method described here such that an incremental addition of
ten (10) mg/L of alum (or equivalent amount of ferric salt) results in a TOC
removal of less than or equal to 0.3 mg/L. The percent removal of TOC at this
point on the "TOC removal versus coagulant dose" curve is then defined as the
minimum TOC removal required for the system. Once approved by the department,
this minimum requirement supersedes the minimum TOC removal required by Table 1
of this rule. This requirement will be effective until such time as the
department approves a new value based on the results of a new bench- and
pilot-scale test. Failure to achieve department-set alternative minimum TOC
removal levels is a violation.
(II)
Bench- or pilot-scale testing of enhanced coagulation must be conducted by
using representative water samples and adding 10 mg/L increments of alum (or
equivalent amounts of ferric salt) until the pH is reduced to a level less than
or equal to the enhanced coagulation Step 2 target pH shown in Table 2.
Table 2: Enhanced Coagulation
Step 2 Target pH
|
Alkalinity (mg/L as CaCO3) |
Target pH |
|
0-60 |
5.5 |
|
>60-120 |
6.3 |
|
>120-240 |
7.0 |
|
>240 |
7.5 |
(III)
For waters with alkalinities of less than sixty (60) mg/L for which addition of
small amounts of alum or equivalent addition of iron coagulant drives the pH
below 5.5 before significant TOC removal occurs, the system must add necessary
chemicals to maintain the pH between 5.3 and 5.7 in samples until the TOC
removal of 0.3 mg/L per 10 mg/L alum added (or equivalent addition of iron
coagulant) is reached.
(IV) The
system may operate at any coagulant dose or pH necessary (consistent with other
regulatory requirements) to achieve the minimum TOC percent removal approved
under subparagraph (3)(C)3.C. of this rule.
(V) If the TOC removal is consistently less
than 0.3 mg/L of TOC per 10 mg/L of incremental alum dose at all dosages of
alum (or equivalent addition of iron coagulant), the water is deemed to contain
TOC not amenable to enhanced coagulation. The system may then apply to the
department for a waiver of enhanced coagulation
requirements.
4. Compliance calculations.
A. Systems using surface water or ground
water under the direct influence of surface water, other than those identified
in paragraphs (3)(C)1. or (3)(C)2. of this rule, must comply with requirements
contained in subparagraphs (3)(C)3.B. or (3)(C)3.C. of this rule. Systems must
calculate compliance quarterly, beginning after the system has collected twelve
(12) months of data, by determining an annual average using the following
method:
(I) Determine actual monthly TOC
percent removal, equal to: (1 - (treated water TOC/source water TOC)) ×
100;
(II) Determine the required
monthly TOC percent removal;
(III)
Divide the value in part (3)(C)4.A.(I) by the value in part (3)(C)4.A.(II);
and
(IV) Add together the results
of part (3)(C)4.A.(III) for the last twelve (12) months and divide by twelve
(12). If the value calculated is less than 1.00, the system is not in
compliance with the TOC percent removal requirements.
B. Systems may use the following provisions
in lieu of the calculations in subparagraph (3)(C)4.A. of this rule to
determine compliance with TOC percent removal requirements:
(I) In any month that the system's treated or
source water TOC level, measured according to
10 CSR
60-5.010, is less than 2.0 mg/L, the system may assign
a monthly value of 1.0 (in lieu of the value calculated in part (3)(C)4.A.(III)
of this rule);
(II) In any month
that a system practicing softening removes at least 10 mg/L of magnesium
hardness (as CaCO3), the system may assign a monthly
value of 1.0 (in lieu of the value calculated in part (3)(C)4.A.(III) of this
rule);
(III) In any month that the
system's source water SUVA, prior to any treatment and measured according to
10 CSR
60-5.010, is less than or equal to 2.0 L/mg-m, the
system may assign a monthly value of 1.0 (in lieu of the value calculated in
part (3)(C)4.A.(III) of this rule);
(IV) In any month that the system's finished
water SUVA, measured according to
10 CSR
60-5.010, is less than or equal to 2.0 L/mg-m, the
system may assign a monthly value of 1.0 (in lieu of the value calculated in
part (3)(C)4.A.(III) of this rule); and
(V) In any month that a system practicing
enhanced softening lowers alkalinity below sixty (60) mg/L (as
CaCO3), the system may assign a monthly value of 1.0 (in
lieu of the value calculated in part (3)(C)4.A.(III) of this rule).
C. Systems using conventional
treatment and surface water or ground water under the direct influence of
surface water may also comply with the requirements of this rule by meeting the
criteria in paragraphs (3)(C)1. or (3)(C)2. of this rule.
(D) Disinfection Byproducts.
1. Bromate. Compliance must be based on a
running annual arithmetic average, computed quarterly, of monthly samples (or,
for months in which the system takes more than one sample, the average of all
samples taken during the month) collected by the system as prescribed by
paragraph (2)(A)4. of this rule. If the average of samples covering any
consecutive four-quarter period exceeds the MCL, the system is in violation of
the MCL and must notify the public pursuant to
10 CSR
60-8.010, in addition to reporting to the department
pursuant to 10 CSR 60-7.010. If a PWS fails
to complete twelve (12) consecutive months' monitoring, compliance with the MCL
for the last four (4)-quarter compliance period must be based on an average of
the available data.
2. Chlorite.
Compliance must be based on an arithmetic average of each three (3) sample set
taken in the distribution system as prescribed by item (2)(A)3.C.(II) and
subparagraph (2)(A)3.B. of this rule. If the arithmetic average of any three
(3) sample set exceeds the MCL, the system is in violation of the MCL and must
notify the public pursuant to
10 CSR
60-8.010, in addition to reporting to the department
pursuant to 10 CSR 60-7.010.
3. Total Trihalomethane (TTHM) and Haloacetic
Acid (HAA).
A. Stage 2
Disinfectants/Disinfection Byproducts-Locational Running Annual Average (LRAA)
Compliance. The MCLs of 0.080 mg/L for TTHM and 0.060 mg/L for HAA5 must be
complied with as a locational running annual average at each monitoring
location.
B. If the system is
required to conduct quarterly monitoring, the system must make compliance
calculations at the end of the fourth calendar quarter that follows the
compliance date and at the end of each subsequent quarter (or earlier if the
LRAA calculated based on fewer than four (4) quarters of data would cause the
MCL to be exceeded regardless of the monitoring results of subsequent
quarters). If the system is required to conduct monitoring at a frequency that
is less than quarterly, the system must make compliance calculations beginning
with the first compliance sample taken after the compliance date.
C. The department may determine that the
combined distribution system does not include certain consecutive systems based
on factors such as receiving water from a wholesale system only on an emergency
basis or receiving only a small percentage and small volume of water from a
wholesale system. The department may also determine that the combined
distribution system does not include certain wholesale systems based on factors
such as delivering water to a consecutive system only on an emergency basis or
delivering only a small percentage and small volume of water to a consecutive
system.
(E)
Operational Evaluation Levels.
1. The system
has exceeded the operational evaluation level at any monitoring location where
the sum of the two (2) previous quarters of TTHM results plus twice the current
quarter's TTHM result, divided by four (4) to determine an average, exceeds
0.080 mg/L, or where the sum of the two (2) previous quarters of HAA5 results
plus twice the current quarter's HAA5 result, divided by four (4) to determine
an average, exceeds 0.060 mg/L.
2.
If Operational Evaluation Levels are Exceeded.
A. If the system exceeds the operational
evaluation level, the system must conduct an operational evaluation and submit
a written report of the evaluation to the department no later than ninety (90)
days after being notified of the analytical result that causes the system to
exceed the operational evaluation level. The written report must be made
available to the public upon request.
B. The system's operational evaluation must
include an examination of system treatment and distribution operational
practices, including storage tank operations, excess storage capacity,
distribution system flushing, changes in sources or source water quality, and
treatment changes or problems that may contribute to TTHM and HAA5 formation
and what steps could be considered to minimize future exceedences.
(I) The system may request and the department
may allow a limit to the scope of the evaluation if the system is able to
identify the cause of the operational evaluation level exceedance.
(II) The system's request to limit the scope
of the evaluation does not extend the schedule in subparagraph (3)(E)2.A. of
this rule for submitting the written report. The department must approve this
limited scope of evaluation in writing, and the system must keep that approval
with the completed report.
(F) Stage 2 D/DBP Reporting and
Record-Keeping Requirements.
1. Reporting
requirements are found in
10 CSR
60-7.010, Reporting Requirements.
2. Record-keeping requirements are found in
10 CSR
60-9.010, Requirements for Maintaining Public Water
System Records.
Notes
State regulations are updated quarterly; we currently have two versions available. Below is a comparison between our most recent version and the prior quarterly release. More comparison features will be added as we have more versions to compare.
No prior version found.