North Dakota Administrative Code › Title 33.1 - Department of Environmental Quality › Article 33.1-17 - Public Water Supply Systems › Chapter 33.1-17-01 - Public Water Supply Systems in North Dakota › Section 33.1-17-01-11 - Microbiological sampling and monitoring requirements

Current through Supplement No. 393, July, 2024
1.
Monitoring
				requirements.
a. General. The
				provisions set forth under title 40 Code of Federal Regulations part 141,
				subpart Y, include both the maximum contaminant level and treatment technique
				requirements for all public water systems.
b. Sample siting plans. All total coliform
				samples must be collected according to a written sample siting plan. Systems
				must develop a written sample siting plan that identifies the sample collection
				schedule and sampling sites that are representative of the water throughout the
				distribution system. This plan must be submitted to the department. The plan is
				subject to department review and revisions. Routine, repeat, and any sampling
				sites necessary to meet the requirements specified under title 40 Code of
				Federal Regulations part 141, subparts S and Y must be shown on the plan.
(1) The routine samples must be collected at
				regular time intervals throughout the month except that systems using ground
				water and serving four thousand nine hundred people or less may collect all of
				the required samples on a single day if the samples are collected from
				different sites.
(2) Systems must
				take at least the minimum number of required samples even if the system has had
				an E.coli maximum contaminant level violation or has exceeded the coliform
				treatment technique triggers as specified in title 40 Code of Federal
				Regulations part 141, subpart Y.
(3) Systems may take more than the minimum
				number of required routine samples and these results must be used to determine
				whether a coliform treatment technique trigger has been exceeded as specified
				in title 40 Code of Federal Regulations part 141, subpart Y. All routine and
				repeat total coliform samples must be taken in accordance with the existing
				sample siting plan.
(4) Repeat
				monitoring locations must be identified in the sample siting plan. The repeat
				samples must be collected at the following locations, unless the provisions of
				paragraphs (b)(5)(a) or (b)(5)(b) are met:
(a) At least one repeat sample must be
				collected from the original sampling site that was total
				coliform-positive.
(b) At least one
				repeat sample must be collected from a site within five service connections
				upstream of the original total coliform-positive sampling site.
(c) At least one repeat sample must be
				collected from a site within five service connections downstream of the
				original total coliform-positive sampling site.
(5) If the original total coliform-positive
				sampling site is at or one away from the end of the distribution system the
				department may waive the requirement to collect at least one repeat sample
				upstream or downstream of the original total coliform-positive sampling site.
				The system must still take all required repeat samples. However, the department
				may allow alternate sampling locations other than the upstream or downstream
				sites. Systems required to conduct triggered source water monitoring as set
				forth under title 40 Code of Federal Regulations part 141, subpart S, must take
				ground water source samples in addition to the required repeat sampling.
(a) Systems may elect to identify alternative
				fixed repeat locations or criteria for selecting repeat sampling sites on a
				case-by-case basis in a standard operating procedure. These repeat monitoring
				locations should be indicative of a pathway for contamination of the
				distribution system. The department shall review the alternative repeat
				monitoring locations to verify and determine the extent of potential
				contamination of the distribution system at the specific alternative repeat
				monitoring location. The department shall review the alternative repeat
				monitoring locations as needed.
(b)
				Ground water systems which serve one thousand or fewer persons may propose
				repeat sampling locations that differentiate potential source water and
				distribution system contamination, such as by sampling at entry points to the
				distribution system. A ground water system with a single well required to
				conduct triggered source water monitoring may, with the approval of the
				department, take one of its repeat samples at the triggered source water
				monitoring location as set forth under title 40 Code of Federal Regulations
				part 141.402(a), subpart S. The system must demonstrate, to the department's
				satisfaction, the sample siting plan remains representative of water quality in
				the distribution system. If approved by the department, the system may use that
				sample result to meet the monitoring requirements as set forth under title 40
				Code of Federal Regulations part 141.402(a), subpart S and under title 40 Code
				of Federal Regulations part 141.853(a)(5)(ii), subpart Y.
[1] If a repeat sample is taken at a
				triggered source water monitoring location and is positive for E.coli bacteria,
				the system has violated the E.coli maximum contaminant level and must also
				comply with title 40 Code of Federal Regulations part 141.402(a)(3), subpart S.
				If a system takes more than one repeat sample at the triggered source water
				monitoring location, the system may reduce the number of additional source
				water samples required under title 40 Code of Federal Regulations part
				141.402(a)(3), subpart S by the number of repeat samples taken at that location
				that were not positive for E.coli bacteria.
[2] If more than one repeat sample is taken
				at a triggered source water monitoring location under title 40 Code of Federal
				Regulations part 141.402(a), subpart S and more than one repeat sample is
				positive for E.coli bacteria, the system has violated the E.coli maximum
				contaminant level and must also comply with title 40 Code of Federal
				Regulations part 141.403(a)(1), subpart S.
[3] If all repeat samples taken at a
				triggered source water monitoring location are E.coli-negative and a repeat
				sample that is taken at a monitoring location other than the triggered source
				water monitoring location is E.coli-positive, the system has violated the E.
				coli maximum contaminant level, but is not required to comply with title 40
				Code of Federal Regulations part 141.402(a)(3), subpart S.
(6) Any alternative repeat
				monitoring locations or triggered source water monitoring locations as
				specified under title 40 Code of Federal Regulations part 141, subpart Y and
				under title 40 Code of Federal Regulations part 141, subpart S, will be
				reviewed and approved by the department. When using these sites, the system
				must demonstrate that the sample siting plan remains representative of the
				water quality in the distribution system. It may be determined that monitoring
				at the entry point to the distribution system, such as for undisinfected ground
				water systems, is an effective way to differentiate between potential source
				water and distribution system problems.
c. Special purpose samples. Special purpose
				samples, such as those taken to determine whether disinfection practices
				following pipe placement, replacement, or repair are sufficient, and samples
				invalidated by the department or laboratory, must not be used to determine
				whether the coliform treatment technique trigger has been exceeded as specified
				under title 40 Code of Federal Regulations part 141, subpart Y. Repeat samples
				taken in accordance with title 40 Code of Federal Regulations part 141, subpart
				Y are not considered special purpose samples and must be used to determine
				whether the coliform treatment technique trigger has been exceeded.
d. Invalidation of total coliform samples.
				Any total coliform-positive samples invalidated under title 40 Code of Federal
				Regulations part 141, subpart Y, do not count towards meeting the minimum
				monitoring requirements.
The department may invalidate a total coliform-positive
				  sample only if one of the following conditions is met:
(1) The laboratory establishes the total
				coliform-positive result was caused by improper sample analysis.
(2) The department determines, based upon the
				results of the repeat samples as required under title 40 Code of Federal
				Regulations part 141, subpart Y, that the total coliform-positive sample
				resulted from a domestic or other nondistribution system problem. This
				provision applies only to systems that have more than one service connection
				and only if:
(a) All repeat samples collected
				at the same site as the original total coliform-positive sample are also total
				coliform-positive; and
(b) All
				repeat samples collected at a location other than the original total
				coliform-positive sample site are total coliform-negative.
(3) The department may determine that
				substantial grounds exist to indicate that the total coliform-positive result
				was due to a circumstance or condition not reflective of the water quality in
				the distribution system. The system must still collect all repeat samples and
				use them to determine whether a coliform treatment technique trigger has been
				exceeded as specified under title 40 Code of Federal Regulations part 141,
				subpart Y. To invalidate a total coliform-positive sample under this provision,
				the decision and supporting paperwork must be documented in writing and
				approved and signed by the supervisor of the state official who recommended the
				decision. The department shall make this document available to the
				environmental protection agency and to the public. The written documentation
				must state the specific cause of the total coliform-positive sample and what
				action the system has or will take to correct the problem. Invalidation may not
				be based soley on the grounds that all repeat samples are total
				coliform-negative.
A laboratory must invalidate a total coliform sample, unless
				  total coliforms are detected, only if one of the following conditions is
				  met:
(1) The sample produces a turbid
				culture in the absence of gas production using an analytical technique where
				gas formation is examined, such as the multiple-tube fermentation
				technique;
(2) The sample produces
				a turbid culture in the absence of an acid reaction in the presence-absence
				coliform test; or
(3) The sample
				exhibits confluent growth or produces colonies too numerous to count with an
				analytical technique using a membrane filter, such as membrane filter
				technique.
Systems must collect a replacement sample for total coliform
				  bacteria analysis from the same location as the original sample if the original
				  sample is invalidated by the department or laboratory. Replacement samples must
				  be collected within twenty-four hours of notification by the department or
				  laboratory and submitted for total coliform analysis. The system must continue
				  to resample within twenty-four hours and have the sample analyzed for total
				  coliforms until a valid result is obtained. The department may waive the
				  twenty-four hour time limit on a case-by-case basis.
Criteria the department may implement for waiving the
				  twenty-four hour sampling time frame includes the following:
(1) Laboratory closures; or
(2) Mail delivery issues.