S.C. Code Regs. 61-58.14.G - Stage 2 Disinfection Byproducts Rule Compliance Monitoring Location Recommendations

Current through Register Vol. 46, No. 3, March 25, 2022

(1) The IDSE report must include recommendations and justification for where and during what month(s) TTHM and HAA5 monitoring for compliance with requirements of R.61-58.15 should be conducted. Recommendations must be based on the criteria in paragraphs (2) through (5) of this section.
(2) Systems must select the number of monitoring locations specified in the table in this paragraph (2). These recommended locations will be used as R.61-58.15 (Stage 2 Disinfection Byproducts Requirements) routine compliance monitoring locations, unless the Department requires different or additional locations. Monitoring locations should be distributed throughout the distribution system to the extent possible.

WIDETABLE

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Source Water Type

Population size category

Monitoring frequency

Total monitoring locations per monitoring period

Highest TTHM monitoring locations

Highest HAA5 monitoring locations

Existing R.61"58.13 compliance monitoring locations

Subpart H

Less than 500

per year

2

1

1

-

Subpart H

500 - 3,300

per quarter

2

1

1

-

Subpart H

3,301 - 9,999

per quarter

2

1

1

-

Subpart H

10,000 - 49,999

per quarter

4

2

1

1

Subpart H

50,000 - 249,999

per quarter

8

3

3

2

Subpart H

250,000 - 999,999

per quarter

12

5

4

3

Subpart H

1,000,000 - 4,999,999

per quarter

16

6

6

4

Subpart H

5,000,000 or greater

per quarter

20

8

7

5

Ground Water

Less than 500

per year

2

1

1

-

Ground Water

500 - 9,999

per year

2

1

1

-

Ground Water

10,000 - 99,999

per quarter

4

2

1

1

Ground Water

100,000 - 499,999

per quarter

6

3

2

1

Ground Water

500,000 or greater

per quarter

8

3

3

2

(a) All systems must monitor during the month of highest disinfection byproduct (DBP) concentrations.
(b) 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 a 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.
(3) Systems must recommend R.61-58.15 compliance monitoring locations based on standard monitoring results, system specific study results, and R.61-58.13 compliance monitoring results. Systems must follow the protocol in paragraphs (3)(a) through (3)(h) of this section. If required to monitor at more than eight locations, a system must repeat the protocol as necessary. If a system does not have existing R.61-58.13 compliance monitoring results or if they do not have enough existing R.61-58.13 compliance monitoring results, they must repeat the protocol, skipping the provisions of paragraphs (3)(c) and (3)(g) of this section as necessary, until the required total number of monitoring locations have been identified.
(a) Location with the highest TTHM LRAA not previously selected as an R.61-58.15 monitoring location.
(b) Location with the highest HAA5 LRAA not previously selected as an R.61-58.15 monitoring location.
(c) Existing R.61-58.13 average residence time compliance monitoring location (maximum residence time compliance monitoring location for ground water systems) with the highest HAA5 LRAA not previously selected as an R.61-58.15 monitoring location.
(d) Location with the highest TTHM LRAA not previously selected as an R.61-58.15 monitoring location.
(e) Location with the highest TTHM LRAA not previously selected as an R.61-58.15 monitoring location.
(f) Location with the highest HAA5 LRAA not previously selected as an R.61-58.15 monitoring location.
(g) Existing R.61-58.13 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 R.61-58.15 monitoring location.
(h) Location with the highest HAA5 LRAA not previously selected as an R.61-58.15 monitoring location.
(4) A system may recommend locations other than those specified in paragraph (3) of this section if they include a rationale for selecting other locations. If the Department approves the alternate locations, the system must monitor at these locations to determine compliance under R.61-58.15.
(5) The recommended schedule must include R.61-58.15 monitoring during the peak historical month for TTHM and HAA5 concentration, unless the Department approves another month. Once the peak historical month has been identified, and if the system is required to conduct routine monitoring at least quarterly, the system must schedule R.61-58.15 compliance monitoring at a regular frequency of every 90 days or fewer.

Notes

S.C. Code Regs. 61-58.14.G

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