Rules & Regulations of the State of Tennessee
Title 0400 - Environment and Conservation
Subtitle 0400-45 - Division of Water Resources
Chapter 0400-45-01 - Public Water Systems
Section 0400-45-01-.37 - STAGE 2 INITIAL DISTRIBUTION SYSTEM EVALUATION FOR DISINFECTION BYPRODUCTS

Universal Citation: TN Comp Rules and Regs 0400-45-01-.37

Current through September 24, 2024

(1) General Requirements: The requirements of this rule constitute national primary drinking water regulations.

(a) The requirements of this rule constitute national primary drinking water regulations. The regulations in this rule establish monitoring and other requirements for identifying compliance monitoring locations to be used for determining compliance with maximum contaminant levels for total trihalomethanes (TTHM) and haloacetic acids (five)(HAA5) in Rule 0400-45-01-.38 Locational Running Annual Average (LRAA) through the use of an Initial Distribution System Evaluation (IDSE). IDSEs are studies, used in conjunction with, but separate from, compliance monitoring in Rule 0400-45-01-.36, to identify and select LRAA compliance monitoring sites that represent high TTHM and HAA5 levels throughout the distribution system. The studies will be based on system-specific monitoring. As an alternative, you may use other system-specific data that provide equivalent or better information on site selection for monitoring to demonstrate compliance with the LRAAs as provided for in the 40/30 portion of this rule.

(b) Applicability. You are subject to these requirements if your system is a community water system that uses a primary or residual disinfectant other than ultraviolet light or delivers water that has been treated with a primary or residual disinfectant other than ultraviolet light or if your system is a nontransient noncommunity water system that serves at least 10,000 people and adds a primary or residual disinfectant other than ultraviolet light or delivers water that has been treated with a primary or residual disinfectant other than ultraviolet light. You must conduct an Initial Distribution System Evaluation (IDSE), unless you meet the 40/30 certification criteria or the Department has granted a very small system waiver for the IDSE or you meet the criteria defined by the Department for a very small system waiver. If you have a very small system waiver for the IDSE under subparagraph (4)(c) of this rule, you are not required to submit an IDSE report. All other systems must submit an IDSE report, even if you meet the 40/30 certification criteria in subparagraph (4)(c) of this rule.

(c) Schedule.
1. You must comply with the Initial Distribution System Evaluation (IDSE) on the schedule in the following table, based on your system type.

If you serve this population

You must submit your standard monitoring plan or system specific study plan1 or 40/30 certification2 to the

Department by or receive a very small system waiver from the Department by

You must complete your standard monitoring or system specific study by

You must submit your IDSE report to the Department by3

Systems that are not part of a combined distribution system and systems that serve the largest population in the combined distribution system

(i) 100,000 or more

(ii) 50,000-99,999

(iii) 10,000-49,999

(iv)<10.000 ( CWS only)

October 1, 2006

April 1, 2007

October 1, 2007

April 1, 2008

September 30, 2008

March 31, 2009

September 30, 2009

March 31, 2010

January 1, 2009

July 1, 2009

January 1, 2010

July 1, 2010

Other systems that are part of a combined distribution system

(v) Wholesale system or consecutive system

At the same time as the system with the earliest compliance date in the combined distribution system.

At the same time as the system with the earliest compliance date in the combined distribution system

At the same time as the system with the earliest compliance date in the combined distribution system

1 If, within 12 months after the date identified in this column, the Department does not approve your plan or notify you that it has not yet completed its review, you may consider the plan that you submitted as approved. You must implement that plan and you must complete standard monitoring or a system specific study no later than the date identified in the third column.

2 You must submit your 40/30 certification by the date indicated.

3 If, within three months after the date identified in this column (nine months after the date identified in this column if you must comply on the schedule in subpart (c)(1)(iii) of this paragraph, the Department does not approve your IDSE report or notify you that it has not yet completed its review, you may consider the report that you submitted as approved and you must implement the recommended monitoring as required.

2. For the purpose of the schedule in part 1 of this subparagraph 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.

(d) You must conduct standard monitoring that meets the requirements in paragraph (2) of this rule, or a system specific study that meets the requirements in paragraph (3) of this rule, or certify to the Department that you meet 40/30 certification criteria under paragraph (4) of this rule, or qualify for a very small system waiver under paragraph (5) of this rule.
1. You must have taken the full complement of routine TTHM and HAA5 compliance samples required of a system with your population and source water under Rule 0400-45-01-.36 (or you must have taken the full complement of reduced TTHM and HAA5 compliance samples required of a system with your population and source water under Rule 0400-45-01-.36 if you meet reduced monitoring criteria under Rule 0400-45-01-.36) during the period specified in paragraph (4) of this rule to meet the 40/30 certification criteria in paragraph (4) of this rule. You must have taken TTHM and HAA5 samples under Rule 0400-45-01-.36 to be eligible for the very small system waiver in paragraph (5) of this rule.

2. If you have not taken the required samples, you must conduct standard monitoring that meets the requirements in paragraph (2) of this rule, or a system specific study that meets the requirements in paragraph (3) of this rule.

(e) You must use only the analytical methods specified in Rule 0400-45-01-.14, or otherwise approved by the Department or the EPA for monitoring under the provisions of Rule 0400-45-01-.36, this rule and Rule 0400-45-01-.38.

(f) IDSE results will not be used for the purpose of determining compliance with MCLs in Rule 0400-45-01-.06.

(2) Standard Monitoring

(a) Standard monitoring plan. Your standard monitoring plan must comply with parts 1 through 4 of this subparagraph. You must prepare and submit your standard monitoring plan to the Department according to the schedule in subparagraph (1)(c) of this rule.
1. Your standard monitoring plan must include a schematic of your distribution system (including distribution system entry points and their sources, and storage facilities), with notes indicating locations and dates of all projected standard monitoring, and all projected Rule 0400-45-01-.36 compliance monitoring.

2. Your standard monitoring plan must include justification of standard monitoring location selection and a summary of data you relied on to justify standard monitoring location selection.

3. Your standard monitoring plan must specify the population served and system type (subpart H or ground water).

4. You must retain a complete copy of your standard monitoring plan submitted under this subparagraph, including any Department modification of your standard monitoring plan, for as long as you are required to retain your IDSE report under (c)4 of this paragraph.

(b) Standard monitoring.
1. You must monitor as indicated in the table in this part. You must collect dual sample sets at each monitoring location. One sample in the dual sample set must be analyzed for TTHM. The other sample in the dual sample set must be analyzed for HAA5. You must conduct one monitoring period during the peak historical month for TTHM levels or HAA5 levels or the month of warmest water temperature. You must review available compliance, study, or operational data to determine the peak historical month for TTHM or HAA5 levels or warmest water temperature.

Source Water Type

Population Size Category

Monitoring periods and frequency of sampling

Distribution system monitoring locations1

Total per monitoring

period

Near entry points

Average residence

time

High

TTHM

location s

High

HAA5

location s

Subpart H

<500 consecutive systems

One (during peak historical month)2

2

1

1

<500 non-consecutive systems

2

1

1

500-3300 consecutive systems

4 (every 90 days)

2

1

1

500-3300 non-consecutive systems

2

1

1

3,301-9,999

4

1

2

1

10,000-49,999

Six ( every sixty days)

8

1

2

3

2

50,000-249,999

16

3

4

5

4

250,000-999,999

24

4

6

8

6

1,000,000-4,999,999

32

6

8

10

8

>5,000,000

40

8

10

12

10

Ground Water

<500 consecutive systems

One (during peak historical month)2

2

1

1

<500 non-consecutive systems

2

1

1

500-9,999

Four (every 90 days)

2

1

1

10,000-99,999

6

1

1

2

2

100,000-499,999

8

1

1

3

3

>5,000,000

12

2

2

4

4

1 A dual sample set (i.e. a TTHM and an HAA5 sample) must be taken at each monitoring location during each monitoring period.

2 The peak historical month is the month with the highest TTHM or HAA5 levels or the warmest water temperature.

2. You must take samples at locations other than the existing monitoring locations required by Rule 0400-45-01-.36. Monitoring locations must be distributed throughout the distribution system.

3. If the number of entry points to the distribution system is fewer than the specified number of entry point monitoring locations, excess entry point samples must be replaced equally at high TTHM and HAA5 locations. If there is an odd extra location number, you must take a sample at a high TTHM location. If the number of entry points to the distribution system is more than the specified number of entry point monitoring locations, you must take samples at entry points to the distribution system having the highest annual water flows.

4. Your monitoring under this subparagraph may not be reduced under the provisions of Rule 0400-45-01-.15 and the Department may not reduce your monitoring using the provisions of 40 CFR 142.16(m).

(c) IDSE report. Your IDSE report must include the elements required in parts 1 through 4 of this subparagraph. You must submit your IDSE report to the Department according to the schedule in subparagraph (1)(c) of this rule.
1. Your IDSE report must include all TTHM and HAA5 analytical results from Rule 0400-45-01-.36 compliance monitoring and all standard monitoring conducted during the period of the IDSE as individual analytical results and LRAAs presented in a tabular or spreadsheet format acceptable to the Department. If changed from your standard monitoring plan submitted under subparagraph (a) of this paragraph, your report must also include a schematic of your distribution system, the population served, and system type (subpart H or ground water).

2. Your IDSE report must include an explanation of any deviations from your approved standard monitoring plan.

3. You must recommend and justify Locational Running Annual Average compliance monitoring locations and timing based on the protocol in paragraph (6) of this rule.

4. You must retain a complete copy of your IDSE report for 10 years after the date that you submitted your report. If the Department modifies the LRAA monitoring requirements that you recommended in your IDSE report or if the Department approves alternative monitoring locations, you must keep a copy of the Department's notification on file for 10 years after the date of the Department's notification. You must make the IDSE report and any Department notification available for review by the Department or the public.

(3) System Specific Studies

(a) System specific study plan. Your system specific study plan must be based on either existing monitoring results as required under part 1 of this subparagraph or modeling as required under part 2 of this subparagraph. You must prepare and submit your system specific study plan to the Department according to the schedule in subparagraph (1)(c) of this rule.
1. Existing monitoring results. You may comply by submitting monitoring results collected before you are required to begin monitoring under subparagraph (1)(c) of this rule. The monitoring results and analysis must meet the criteria in subparts (i) and (ii) of this part.
(i) Minimum requirements.
(I) TTHM and HAA5 results must be based on samples collected and analyzed in accordance with subparagraph (10)(k) of Rule 0400-45-01-.14. TTHM and HAA5 results must be based on samples collected no earlier than five years prior to the study plan submission date.

(II) The monitoring location and frequency must meet the conditions identified in this item. Each location must be sampled once during the peak historical month for TTHM levels or HAA5 levels or the month of warmest water temperature for every 12 months of data submitted for that location. Monitoring results must include all compliance samples collected in accordance with Rule 0400-45-01-.36 plus additional monitoring results as necessary to meet minimum sample requirements.

System Type

Population Size Category

Number of monitoring

locations

Number of

samples

Subpart H

<500

3

3

3

500-3,300

3

9

9

3,301-9,999

6

36

36

10,000-49,999

12

72

72

50,000-249,999

24

144

144

250,000-999,999

36

216

216

1,000,000-4,999,999

48

288

288

>5,000,000

60

360

360

Ground Water

<500

3

3

3

500-9,999

3

9

9

10,000-99,999

12

48

48

100,000-499,999

18

72

72

>500,000

24

96

96

(ii) Reporting Monitoring Results. You must report the information in this subpart.
(I) You must report previously collected monitoring results and certify that the reported monitoring results include all compliance and non-compliance results generated during the time period beginning with the first reported result and ending with the most recent results from monitoring for compliance with Rule 0400-45-01-.36.

(II) You must certify that the samples were representative of the entire distribution system and that treatment and distribution system have not changed significantly since the samples were collected.

(III) Your study monitoring plan musts include a schematic of your distribution systems (including distribution system entry points and their sources, and storage facilities), with notes indicating the locations and dates of all completed or planned system specific study monitoring.

(IV) Your system specific study plan must specify the population served and system type (subpart H or ground water).

(V) You must retain a complete copy of your system specific study plan submitted under this part, including any Department modification of your system specific study plan, for as long as you are required to retain your IDSE report under part (b)5 of this paragraph.

(VI) If you submit previously collected data that fully meets the number of samples required under item (i)(II) of this part and the Department rejects some of the data, you must either conduct additional monitoring to replace rejected data on a schedule the Department approves or conduct standard monitoring under paragraph (2) of this rule.

2. Modeling. You may comply through analysis of an extended period simulation hydraulic model. The extended period simulation hydraulic model and analysis must meet the criteria in part (a)2 of this paragraph.
(i) Minimum requirements
(I) The model must simulate 24-hour variation in demand and show a consistently repeating 24-hour pattern of residence time.

(II) The model must represent the criteria listed in items I through IX of this subpart.
I. 75% of pipe volume;

II. 50% of pipe length;

III. All pressure zones;

IV. All 12-inch diameter and larger pipes;

V. All 8-inch and larger pipes that connect pressure zones, influence zones from different sources, storage facilities, major demand areas, pumps and control valves, or are known or expected to be significant conveyors of water;

VI. All 6-inch and larger pipes that connects remote areas of a distribution system to the main portion of the system;

VII. All storage facilities with standard operations represented in the model;

VIII. All active pump stations with controls represented in the model; and

IX. All active control valves.

(III) The model must be calibrated, or have calibration plans, for the current configuration of the distribution system during the period of high TTHM formation potential. All storage facilities must be evaluated as part of the calibration process. All required calibration must be completed no later than 12-months after plan submission.

(ii) Reporting modeling. Your system specific study plan must include the information in this subpart.
(I) Tabular or spreadsheet data demonstrating that the model meets requirements in item (i)(II) of this part.

(II) A description of all calibration activities undertaken, and if calibration is complete, a graph of predicted tank levels versus measured tank levels for the storage facility with the highest residence time in each pressure zone, and a time series graph of the residence time at the longest residence time storage facility in the distribution system showing the prediction for the entire simulation period (i.e. from time zero until the time it takes for the model to reach a consistently repeating pattern of residence time).

(III) Model input showing preliminary 24-hour average residence time predictions throughout the distribution system.

(IV) Timing and number of samples representative of the distribution systems planned for at least one monitoring period of TTHM and HAA5 dual sample monitoring at a number of locations no less than would be required for the system under standard monitoring in paragraph (2) of this rule during the historical month of high TTHM. These samples must be taken at locations other than existing compliance monitoring locations required by Rule 0400-45-01-.36.

(V) Description of how all requirements will be completed no later than 12 months after you submit your system specific study plan.

(VI) Schematic of your distribution system (including distribution system entry points and their sources, and storage facilities), with notes indicating the locations and dates of all completed system specific study monitoring (if calibration is complete) and all compliance monitoring results collected in accordance with Rule0400-45-01-.36.

(VII) Population served and system type (subpart H or ground water).

(VIII) You must retain a complete copy of your system specific study plan submitted under this part, including any Department modification of your system specific study plan, for as long as you are required to retain your IDSE report under part (b)7 of this paragraph.

(iii) If you submit a model that does not fully meet the requirements under this part, you must correct the deficiencies and respond to Department inquiries concerning the model. If you fail to correct deficiencies or respond to inquiries to the Department's satisfaction, you must conduct standard monitoring under paragraph (2) of this rule.

(b) IDSE report. Your IDSE report must include the elements required in parts 1 through 6 of this subparagraph. You must submit your IDSE report according to the schedule in subparagraph (1)(c) of this paragraph.
1. Your IDSE report must include all TTHM and HAA5 analytical results from Rule 0400-45-01-.36 compliance monitoring and all system specific study monitoring conducted during the period of the system specific study presented in a tabular or spreadsheet format acceptable to the Department. If changed from your system specific study plan submitted under subparagraph (a) of this paragraph, your IDSE report must also include a schematic of your distribution system, the population served, and system type (subpart H or ground water).

2. If you used the modeling provision under part (a)2 of this paragraph, you must include final information for the elements described in subpart (a)2(ii) of this paragraph, and a 24-hour time series graph of residence time for each Rule 0400-45-01-.38 compliance monitoring location selected.

3. You must recommend and justify Rule 0400-45-01-.38 compliance monitoring locations and timing based on the protocol in part (6) of this rule.

4. Your IDSE report must include an explanation of any deviations from your approved system specific study plan.

5. Your IDSE report must include the basis (analytical and modeling results) and justification you used to select the recommended Rule 0400-45-01-.38 monitoring locations.

6. You may submit your IDSE report in lieu of your system specific study plan on the schedule identified in subparagraph (1)(c) of this rule for submission of the system specific study plan if you believe that you have the necessary information by the time that the system specific study plan is due. If you elect this approach, your IDSE report must also include all information required under subparagraph (a) of this paragraph.

7. You must retain a complete copy of your IDSE report submitted under this subparagraph for 10 years after the date that you submitted your IDSE report. If the Department modifies the Rule 0400-45-01-.38 monitoring requirements that you recommended in your IDSE report or if the Department approves alternative monitoring locations, you must keep a copy of the Department's notification on file for 10 years after the date of the Department's notification. You must make the IDSE report and any Department notification available for review by the Department or the public.

(4) 40/30 certification

(a) Eligibility. You are eligible for 40/30 certification if you had no TTHM or HAA5 monitoring violations under Rule0400-45-01-.36 and no individual sample exceeded 0.040 mg/L for TTHM or 0.030 mg/L for HAA5 during an eight consecutive calendar quarter period beginning no earlier than the date specified below:

If your 40/30 certification is due

Then your eligibility for 40/30 certification is based on eight consecutive calendar quarters of compliance monitoring required by Rule 0400-45-01-.36 beginning no earlier than1

(1) October 1, 2006

January 2004

(2) April 1, 2007

January 2004

(3) October 1, 2007

January 2005

(4) April 1, 2008

January 2005

1 Unless you are on reduced monitoring under Rule 0400-45-01-.36 and were not required to monitor during the specified period. If you did not monitor during the specified period, you must base your eligibility on compliance samples taken during the 12 months preceding the specified period.

(b) 40/30 certification.
1. You must certify to the Department that every individual compliance sample taken under Rule 0400-45-01-.36 during the period specified in subparagraph (a) of this paragraph was less than or equal to 0.040 mg/L for TTHM and 0.030mg/L for HAA5, and that you have not had any TTHM or HAA5 monitoring violations during the period specified in subparagraph (a) of this paragraph.

2. The Department may require you to submit compliance monitoring results, distribution system schematics and/or recommended LRAA compliance monitoring locations in addition to your certification. If you fail to submit the requested information, the Department may require standard monitoring under paragraph (2) of this rule or a system specific study under paragraph (3) of this rule.

3. The Department may still require standard monitoring under paragraph (2) of this rule or a system specific study under paragraph (3) of this rule even if you meet the criteria in subparagraph (a) of this paragraph.

4. You must retain a complete copy of your certification submitted for 10 years after the date that you submitted your certification. You must make the certification, all data upon which the certification is based, and any Department notification available for review by the Department or the public.

(5) Very small system waivers

(a) If you serve fewer than 500 people and you have taken TTHM and HAA5 samples under Rule 0400-45-01-.36, you are not required to comply with this rule unless the Department notifies you that you must conduct standard monitoring under paragraph (2) of this rule or a system specific study under paragraph (3) of this rule.

(b) If you have not taken TTHM and HAA5 samples under Rule 0400-45-01-.36 or if the Department notifies you that you must comply with this rule, you must conduct standard monitoring under paragraph (2) of this rule or a system specific study under paragraph (3) of this rule.

(6) LRAA compliance monitoring location recommendations

(a) Your IDSE report must include your recommendations and justification for where and during what month(s) TTHM and HAA5 monitoring for LRAA should be conducted. You must base your recommendations on the criteria in subparagraphs (b) through (e) of this paragraph.

(b) You must select the number of monitoring locations specific in the table in this subparagraph. You will use these recommended locations as LRAA compliance monitoring locations unless the Department requires different or additional locations. You should distribute locations throughout the distribution system to the extent possible.

Source water type

Population size category

Monitoring frequency 1

Distribution system monitoring location

Total per monitoring

period 2

Highest

TTHM

locations

Highest

HAA5

locations

Existing compliance

locations

Subpart H

<500

Per year

2

1

1

500-3,300

Per quarter

2

1

1

3,301-9,999

Per quarter

2

1

1

10,000-49,999

Per quarter

4

2

1

1

50,000-249,999

Per quarter

8

3

3

2

250,000-999,999

Per quarter

12

5

4

3

1,000,000-499,000

Per quarter

16

6

6

4

>5,000,000

Per quarter

20

8

7

5

Ground Water

<500

Per year

2

1

1

500-9,999

Per year

2

1

1

10,000-99,999

Per quarter

4

2

1

1

100,000-499,999

Per quarter

6

3

2

1

>5,000,000

Per quarter

8

3

3

2

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 subpart H systems serving 500-3,300. Systems on annual monitoring and subpart H systems serving 500-3,300 are required to take individual TTHM and HAA5 samples (instead of dual sample set) at the locations with the highest TTHM and HAA5 concentrations, respectively. Only one location with a dual sample set per monitoring period is needed if highest TTHM and HAA5 concentrations occur at the same location and month if monitored annually.

(c) You must recommend LRAA compliance monitoring locations based on standard monitoring results, system specific study results, and compliance monitoring results collected under Rule 0400-45-01-.36. You must follow the protocol in parts 1 through 8 of this subparagraph. If required to monitor at more than eight locations, you must repeat the protocol as necessary. If you do not have existing compliance monitoring results collected under Rule 0400-45-01-.36 or if you do not have enough existing compliance monitoring results taken under Rule 0400-45-01-.36, you must repeat the protocol, skipping the provisions of parts 3 and 7 of this subparagraph as necessary, until you have identified the required total number of monitoring locations.
1. Location with the highest TTHM LRAA not previously selected as a LRAA monitoring location.

2. Location with the highest HAA5 LRAA not previously selected as a LRAA monitoring location.

3. Existing Rule 0400-45-01-.36 average residence time compliance monitoring location (maximum residence time compliance monitoring location for ground water system) with the highest HAA5 LRAA not previously selected as a LRAA monitoring location.

4. Location with the highest TTHM LRAA not previously selected as a LRAA monitoring location.

5. Location with the highest TTHM LRAA not previously selected as a LRAA monitoring location.

6. Location with the highest HAA5 LRAA not previously selected as a LRAA monitoring location.

7. Existing Rule 0400-45-01-.36 average residence time compliance monitoring location (maximum residence time compliance monitoring location for ground water systems) with the highest TTHM LRAA not previously selected as a LRAA monitoring location.

8. Location with the highest HAA5 LRAA not previously selected as a LRAA monitoring location.

(d) You may recommend locations other than those specified in subparagraph (c) of this paragraph if you include a rationale for selecting other locations. If the Department approves the alternate locations, you must monitor at these locations to determine compliance under Rule 0400-45-01-.38.

(e) Your recommended schedule must include LRAA monitoring during the peak historical month for TTHM and HAA5 concentration, unless the Department approves another month. Once you have identified the peak historical month, and if you are required to conduct routine monitoring at least quarterly, you must schedule LRAA compliance monitoring at a regular frequency of every 90 days or fewer.

Authority: T.C.A. §§ 68-221-701 et seq. and 4-5-201 et seq.

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