[Code of Federal Regulations] [Title 40, Volume 19] [Revised as of July 1, 2002] From the U.S. Government Printing Office via GPO Access [CITE: 40CFR141.24] [Page 363-372] TITLE 40--PROTECTION OF ENVIRONMENT CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) PART 141--NATIONAL PRIMARY DRINKING WATER REGULATIONS--Table of Contents Subpart C--Monitoring and Analytical Requirements Sec. 141.24 Organic chemicals, sampling and analytical requirements. (a)-(d) [Reserved] (e) Analyses for the contaminants in this section shall be conducted using the following EPA methods or their equivalent as approved by EPA. (1) The following documents are incorporated by reference. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be inspected at EPA's Drinking Water Docket, 401 M St., SW., Washington, DC 20460; or at the Office of the Federal Register, 800 North Capitol Street, NW., Suite 700, Washington, DC. Method 508A and 515.1 are in Methods for the Determination of Organic Compounds in Drinking Water, EPA/600/4-88-039, December 1988, Revised, July 1991. Methods 547, 550 and 550.1 are in Methods for the Determination of Organic Compounds in Drinking Water--Supplement I, EPA/600-4-90-020, July 1990. Methods 548.1, 549.1, 552.1 and 555 are in Methods for the Determination of Organic Compounds in Drinking Water--Supplement II, EPA/600/R-92-129, August 1992. Methods 502.2, 504.1, 505, 506, 507, 508, 508.1, 515.2, 524.2 525.2, 531.1, 551.1 and 552.2 are in Methods for the Determination of Organic Compounds in Drinking Water--Supplement III, EPA/600/R-95-131, August 1995. Method 1613 is titled ``Tetra-through Octa-Chlorinated Dioxins and Furans by Isotope-Dilution HRGC/HRMS'', EPA/821-B-94-005, October 1994. These documents are available from the National Technical Information Service, NTIS PB91-231480, PB91-146027, PB92-207703, PB95-261616 and PB95-104774, U.S. Department of Commerce, 5285 Port Royal Road, Springfield, Virginia 22161. The toll-free number is 800-553-6847. Method 6651 shall be followed in accordance with Standard Methods for the Examination of Water and Wastewater, 18th edition, 1992 and 19th edition, 1995, American Public Health Association (APHA); either edition may be used. Method 6610 shall be followed in accordance with the Supplement to the 18th edition of Standard Methods for the Examination of Water and Wastewater, 1994 or with the 19th edition of Standard Methods for the Examination of Water and Wastewater, 1995, APHA; either publication may be used. The APHA documents are available from APHA, 1015 Fifteenth Street NW., Washington, D.C. 20005. Other required analytical test procedures germane to the conduct of these analyses are contained in Technical Notes on Drinking Water Methods, EPA/600/R-94-173, October 1994, NTIS PB95-104766. EPA Methods 515.3 and 549.2 are available from U.S. Environmental Protection Agency, National Exposure Research Laboratory (NERL)-Cincinnati, 26 West Martin Luther King Drive, Cincinnati, OH 45268. ASTM Method D 5317-93 is available in the Annual Book of ASTM Standards, 1996, Vol. 11.02, American Society for Testing and Materials, 100 Barr Harbor Drive, West Conshohocken, PA 19428, or in any edition published after 1993. ------------------------------------------------------------------------ Contaminant Method \1\ ------------------------------------------------------------------------ Benzene................................... 502.2, 524.2 Carbon tetrachloride 502.2, 524.2, 551.1 Chlorobenzene 502.2, 524.2 1,2-Dichlorobenzene....................... 502.2, 524.2 1,4-Dichlorobenzene....................... 502.2, 524.2 1,2-Dichloroethane........................ 502.2, 524.2 cis-Dichloroethylene...................... 502.2, 524.2 trans-Dichloroethylene.................... 502.2, 524.2 Dichloromethane........................... 502.2, 524.2 1,2-Dichloropropane....................... 502.2, 524.2 Ethylbenzene.............................. 502.2, 524.2 Styrene................................... 502.2, 524.2 Tetrachloroethylene....................... 502.2, 524.2, 551.1 1,1,1-Trichloroethane..................... 502.2, 524.2, 551.1 Trichloroethylene......................... 502.2, 524.2, 551.1 Toluene................................... 502.2, 524.2 1,2,4-Trichlorobenzene.................... 502.2, 524.2 1,1-Dichloroethylene...................... 502.2, 524.2 1,1,2-Trichloroethane..................... 502.2, 524.2, 551.1 Vinyl chloride............................ 502.2, 524.2 Xylenes (total)........................... 502.2, 524.2 2,3,7,8-TCDD (dioxin)..................... 1613 2,4-D\4\ (as acid, salts and esters)...... 515.2, 555, 515.1, 515.3, D5317-93 [[Page 364]] 2,4,5-TP \4\ (Silvex)..................... 515.2, 555, 515.1, 515.3, D5317-93 Alachlor \2\.............................. 507, 525.2, 508.1, 505, 551.1 Atrazine \2\.............................. 507, 525.2, 508.1, 505, 551.1 Benzo(a)pyrene............................ 525.2, 550, 550.1 Carbofuran................................ 531.1, 6610 Chlordane................................. 508, 525.2, 508.1, 505 Dalapon................................... 552.1, 515.1, 552.2, 515.3 Di(2-ethylhexyl)adipate................... 506, 525.2 Di(2-ethylhexyl)phthalate................. 506, 525.2 Dibromochloropropane (DBCP)............... 504.1, 551.1 Dinoseb \4\............................... 515.2, 555, 515.1, 515.3 Diquat.................................... 549.2 Endothall................................. 548.1 Endrin.................................... 508, 525.2, 508.1, 505, 551.1 Ethylene dibromide (EDB).................. 504.1, 551.1 Glyphosate................................ 547, 6651 Heptachlor................................ 508, 525.2, 508.1, 505, 551.1 Heptachlor Epoxide........................ 508, 525.2, 508.1, 505, 551.1 Hexachlorobenzene......................... 508, 525.2, 508.1, 505, 551.1 Hexachlorocyclopentadiene................. 508, 525.2, 508.1, 505, 551.1 Lindane................................... 508, 525.2, 508.1, 505, 551.1 Methoxychlor.............................. 508, 525.2, 508.1, 505, 551.1 Oxamyl.................................... 531.1, 6610 PCBs \3\ (as decachlorobiphenyl).......... 508A (as Aroclors)......................... 508.1, 508, 525.2, 505 Pentachlorophenol......................... 515.2, 525.2, 555, 515.1, 515.3, D5317-93 Picloram \4\.............................. 515.2, 555, 515.1, 515.3, D5317-93 Simazine \2\.............................. 507, 525.2, 508.1, 505, 551.1 Toxaphene................................. 508, 508.1, 525.2, 505 Total Trihalomethanes..................... 502.2, 524.2, 551.1 ------------------------------------------------------------------------ \1\ For previously approved EPA methods which remain available for compliance monitoring until June 1, 2001, see paragraph (e)(2) of this section. \2\ Substitution of the detector specified in Method 505, 507, 508 or 508.1 for the purpose of achieving lower detection limits is allowed as follows. Either an electron capture or nitrogen phosphorous detector may be used provided all regulatory requirements and quality control criteria are met. \3\ PCBs are qualitatively identified as Aroclors and measured for compliance purposes as decachlorobiphenyl. Users of Method 505 may have more difficulty in achieving the required detection limits than users of Methods 508.1, 525.2 or 508. \4\ Accurate determination of the chlorinated esters requires hydrolysis of the sample as described in EPA Methods 515.1, 515.2, 515.3 and 555, and ASTM Method D 5317-93. (2) The following EPA methods will remain available for compliance monitoring until June 1, 2001. The following documents are incorporated by reference. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR Part 51. Copies may be inspected at EPA's Drinking Water Docket, 401 M St., SW., Washington, DC 20460; or at the Office of the Federal Register, 800 North Capitol Street, NW., Suite 700, Washington, DC. EPA methods 502.2 Rev. 2.0, 505 Rev. 2.0, 507 Rev. 2.0, 508 Rev. 3.0, 531.1 Rev. 3.0 are in ``Methods for the Determination of Organic Compounds in Drinking Water'', December 1988, revised July 1991; methods 506 and 551 are in ``Methods for the Determination of Organic Compounds in Drinking Water--Supplement I'', July 1990; methods 515.2 Rev. 1.0 and 524.2 Rev. 4.0 are in ``Methods for the Determination of Organic Compounds in Drinking Water--Supplement II,'' August 1992; and methods 504.1 Rev. 1.0, 508.1 Rev. 1.0, 525.2 Rev.1.0 are available from US EPA NERL, Cincinnati, OH 45268 (f) Beginning with the initial compliance period, analysis of the contaminants listed in Sec. 141.61(a) (1) through (21) for the purpose of determining compliance with the maximum contaminant level shall be conducted as follows: (1) Groundwater systems shall take a minimum of one sample at every entry point to the distribution system which is representative of each well after treatment (hereafter called a sampling point). Each sample must be taken at the same sampling point unless conditions make another sampling point more representative of each source, treatment plant, or within the distribution system. (2) Surface water systems (or combined surface/ground) shall take a minimum of one sample at points in the distribution system that are representative of each source or at each entry point to the distribution system after treatment (hereafter called a sampling point). Each sample must be taken at the same sampling point unless conditions make another sampling point more representative of each source, treatment plant, or within the distribution system. (3) If the system draws water from more than one source and the sources are combined before distribution, the system must sample at an entry point to the distribution system during periods of normal operating conditions (i.e., when water representative of all sources is being used). (4) Each community and non-transient non-community water system shall take four consecutive quarterly samples for each contaminant listed in Sec. 141.61(a) (2) through (21) during each compliance period, beginning in the initial compliance period. (5) If the initial monitoring for contaminants listed in Sec. 141.61(a) (1) [[Page 365]] through (8) and the monitoring for the contaminants listed in Sec. 141.61(a) (9) through (21) as allowed in paragraph (f)(18) has been completed by December 31, 1992, and the system did not detect any contaminant listed in Sec. 141.61(a) (1) through (21), then each ground and surface water system shall take one sample annually beginning with the initial compliance period. (6) After a minimum of three years of annual sampling, the State may allow groundwater systems with no previous detection of any contaiminant listed in Sec. 141.61(a) to take one sample during each compliance period. (7) Each community and non-transient non-community ground water system which does not detect a contaminant listed in Sec. 141.61(a) (1) through (21) may apply to the State for a waiver from the requirements of paragraphs (f)(5) and (f)(6) of this section after completing the initial monitoring. (For purposes of this section, detection is defined as <0.0005 mg/l.) A waiver shall be effective for no more than six years (two compliance periods). States may also issue waivers to small systems for the initial round of monitoring for 1,2,4-trichlorobenzene. (8) A State may grant a waiver after evaluating the following factor(s): (i) Knowledge of previous use (including transport, storage, or disposal) of the contaminant within the watershed or zone of influence of the system. If a determination by the State reveals no previous use of the contaminant within the watershed or zone of influence, a waiver may be granted. (ii) If previous use of the contaminant is unknown or it has been used previously, then the following factors shall be used to determine whether a waiver is granted. (A) Previous analytical results. (B) The proximity of the system to a potential point or non-point source of contamination. Point sources include spills and leaks of chemicals at or near a water treatment facility or at manufacturing, distribution, or storage facilities, or from hazardous and municipal waste landfills and other waste handling or treatment facilities. (C) The environmental persistence and transport of the contaminants. (D) The number of persons served by the public water system and the proximity of a smaller system to a larger system. (E) How well the water source is protected against contamination, such as whether it is a surface or groundwater system. Groundwater systems must consider factors such as depth of the well, the type of soil, and wellhead protection. Surface water systems must consider watershed protection. (9) As a condition of the waiver a groundwater system must take one sample at each sampling point during the time the waiver is effective (i.e., one sample during two compliance periods or six years) and update its vulnerability assessment considering the factors listed in paragraph (f)(8) of this section. Based on this vulnerability assessment the State must reconfirm that the system is non-vulnerable. If the State does not make this reconfirmation within three years of the initial determination, then the waiver is invalidated and the system is required to sample annually as specified in paragraph (5) of this section. (10) Each community and non-transient non-community surface water system which does not detect a contaminant listed in Sec. 141.61(a) (1) through (21) may apply to the State for a waiver from the requirements of (f)(5) of this section after completing the initial monitoring. Composite samples from a maximum of five sampling points are allowed, provided that the detection limit of the method used for analysis is less than one-fifth of the MCL. Systems meeting this criterion must be determined by the State to be non-vulnerable based on a vulnerability assessment during each compliance period. Each system receiving a waiver shall sample at the frequency specified by the State (if any). (11) If a contaminant listed in Sec. 141.61(a) (2) through (21) is detected at a level exceeding 0.0005 mg/l in any sample, then: (i) The system must monitor quarterly at each sampling point which resulted in a detection. (ii) The State may decrease the quarterly monitoring requirement speci fied in paragraph (f)(11)(i) of this section provided it has determined that [[Page 366]] the system is reliably and consistently below the maximum contaminant level. In no case shall the State make this determination unless a groundwater system takes a minimum of two quarterly samples and a surface water system takes a minimum of four quarterly samples. (iii) If the State determines that the system is reliably and consistently below the MCL, the State may allow the system to monitor annually. Systems which monitor annually must monitor during the quarter(s) which previously yielded the highest analytical result. (iv) Systems which have three consecutive annual samples with no detection of a contaminant may apply to the State for a waiver as specified in paragraph (f)(7) of this section. (v) Groundwater systems which have detected one or more of the following two-carbon organic compounds: trichloroethylene, tetrachloroethylene, 1,2-dichloroethane, 1,1,1-trichloroethane, cis-1,2- dichloroethylene, trans-1,2-dichloroethylene, or 1,1-dichloroethylene shall monitor quarterly for vinyl chloride. A vinyl chloride sample shall be taken at each sampling point at which one or more of the two- carbon organic compounds was detected. If the results of the first analysis do not detect vinyl chloride, the State may reduce the quarterly monitoring frequency of vinyl chloride monitoring to one sample during each compliance period. Surface water systems are required to monitor for vinyl chloride as specified by the State. (12) Systems which violate the requirements of Sec. 141.61(a) (1) through (21), as determined by paragraph (f)(15) of this section, must monitor quarterly. After a minimum of four consecutive quarterly samples which show the system is in compliance as specified in paragraph (f)(15) of this section the system and the State determines that the system is reliably and consistently below the maximum contaminant level, the system may monitor at the frequency and times specified in paragraph (f)(11)(iii) of this section. (13) The State may require a confirmation sample for positive or negative results. If a confirmation sample is required by the State, the result must be averaged with the first sampling result and the average is used for the compliance determination as specified by paragraph (f)(15). States have discretion to delete results of obvious sampling errors from this calculation. (14) The State may reduce the total number of samples a system must analyze by allowing the use of compositing. Composite samples from a maximum of five sampling points are allowed, provided that the detection limit of the method used for analysis is less than one-fifth of the MCL. Compositing of samples must be done in the laboratory and analyzed within 14 days of sample collection. (i) If the concentration in the composite sample is greater than or equal to 0.0005 mg/l for any contaminant listed in Sec. 141.61(a), then a follow-up sample must be taken within 14 days at each sampling point included in the composite, and be analyzed for that contaminant. (ii) If duplicates of the original sample taken from each sampling point used in the composite sample are available, the system may use these instead of resampling. The duplicates must be analyzed and the results reported to the State within 14 days after completing analysis of the composite sample, provided the holding time of the sample is not exceeded. (iii) If the population served by the system is 3,300 persons, then compositing may only be permitted by the State at sampling points within a single system. In systems serving [le] 3,300 persons, the State may permit compositing among different systems provided the 5- sample limit is maintained. (iv) Compositing samples prior to GC analysis. (A) Add 5 ml or equal larger amounts of each sample (up to 5 samples are allowed) to a 25 ml glass syringe. Special precautions must be made to maintain zero headspace in the syringe. (B) The samples must be cooled at 4 deg.C during this step to minimize volatilization losses. (C) Mix well and draw out a 5-ml aliquot for analysis. (D) Follow sample introduction, purging, and desorption steps described in the method. [[Page 367]] (E) If less than five samples are used for compositing, a proportionately small syringe may be used. (v) Compositing samples prior to GC/MS analysis. (A) Inject 5-ml or equal larger amounts of each aqueous sample (up to 5 samples are allowed) into a 25-ml purging device using the sample introduction technique described in the method. (B) The total volume of the sample in the purging device must be 25 ml. (C) Purge and desorb as described in the method. (15) Compliance with Sec. 141.61(a) (1) through (21) shall be determined based on the analytical results obtained at each sampling point. (i) For systems which are conducting monitoring at a frequency greater than annual, compliance is determined by a running annual average of all samples taken at each sampling point. If the annual average of any sampling point is greater than the MCL, then the system is out of compliance. If the initial sample or a subsequent sample would cause the annual average to be exceeded, then the system is out of compliance immediately. (ii) If monitoring is conducted annually, or less frequently, the system is out of compliance if the level of a contaminant at any sampling point is greater than the MCL. If a confirmation sample is required by the State, the determination of compliance will be based on the average of two samples. (16) [Reserved] (17) Analysis under this section shall only be conducted by laboratories that are certified by EPA or the State according to the following conditions (laboratories may conduct sample analysis under provisional certification until January 1, 1996): (i) To receive certification to conduct analyses for the contaminants in Sec. 141.61(a) (2) through (21) the laboratory must: (A) Analyze Performance Evaluation (PE) samples provided by EPA, the State, or by a third party (with the approval of the State or EPA) at least once a year by each method for which the laboratory desires certification. (B) Achieve the quantitative acceptance limits under paragraphs (f)(17)(i)(C) and (D) of this section for at least 80 percent of the regulated organic contaminants included in the PE sample. (C) Achieve quantitative results on the analyses performed under paragraph (f)(17)(i)(A) of this section that are within 20% of the actual amount of the substances in the Performance Evaluation sample when the actual amount is greater than or equal to 0.010 mg/l. (D) Achieve quantitative results on the analyses performed under paragraph (f)(17)(i)(A) of this section that are within 40 percent of the actual amount of the substances in the Performance Evaluation sample when the actual amount is less than 0.010 mg/l. (E) Achieve a method detection limit of 0.0005 mg/l, according to the procedures in appendix B of part 136. (ii) To receive certification to conduct analyses for vinyl chloride, the laboratory must: (A) Analyze Performance Evaluation (PE) samples provided by EPA, the State, or by a third party (with the approval of the State or EPA) at least once a year by each method for which the laboratory desires certification. (B) Achieve quantitative results on the analyses performed under paragraph (f)(17)(ii)(A) of this section that are within 40 percent of the actual amount of vinyl chloride in the Performance Evaluation sample. (C) Achieve a method detection limit of 0.0005 mg/l, according to the procedures in appendix B of part 136. (D) Obtain certification for the contaminants listed in Sec. 141.61(a)(2) through (21). (18) States may allow the use of monitoring data collected after January 1, 1988, required under section 1445 of the Act for purposes of initial monitoring compliance. If the data are generally consistent with the other requirements of this section, the State may use these data (i.e., a single sample rather than four quarterly samples) to satisfy the initial monitoring requirement of paragraph (f)(4) of this section. Systems which use grandfathered samples and did not detect any contaminant listed Sec. 141.61(a)(2) through (21) shall begin monitoring annually in accordance [[Page 368]] with paragraph (f)(5) of this section beginning with the initial compliance period. (19) States may increase required monitoring where necessary to detect variations within the system. (20) Each certified laboratory must determine the method detection limit (MDL), as defined in appendix B to part 136, at which it is capable of detecting VOCs. The acceptable MDL is 0.0005 mg/l. This concentration is the detection concentration for purposes of this section. (21) Each public water system shall monitor at the time designated by the State within each compliance period. (g) [Reserved] (h) Analysis of the contaminants listed in Sec. 141.61(c) for the purposes of determining compliance with the maximum contaminant level shall be conducted as follows: \7\ --------------------------------------------------------------------------- \7\ Monitoring for the contaminants aldicarb, aldicarb sulfoxide, and aldicarb sulfone shall be conducted in accordance with Sec. 141.40. --------------------------------------------------------------------------- (1) Groundwater systems shall take a minimum of one sample at every entry point to the distribution system which is representative of each well after treatment (hereafter called a sampling point). Each sample must be taken at the same sampling point unless conditions make another sampling point more representative of each source or treatment plant. (2) Surface water systems shall take a minimum of one sample at points in the distribution system that are representative of each source or at each entry point to the distribution system after treatment (hereafter called a sampling point). Each sample must be taken at the same sampling point unless conditions make another sampling point more representative of each source or treatment plant. Note: For purposes of this paragraph, surface water systems include systems with a combination of surface and ground sources. (3) If the system draws water from more than one source and the sources are combined before distribution, the system must sample at an entry point to the distribution system during periods of normal operating conditions (i.e., when water representative of all sources is being used). (4) Monitoring frequency: (i) Each community and non-transient non-community water system shall take four consecutive quarterly samples for each contaminant listed in Sec. 141.61(c) during each compliance period beginning with the initial compliance period. (ii) Systems serving more than 3,300 persons which do not detect a contaminant in the initial compliance period may reduce the sampling frequency to a minimum of two quarterly samples in one year during each repeat compliance period. (iii) Systems serving less than or equal to 3,300 persons which do not detect a contaminant in the initial compliance period may reduce the sampling frequency to a minimum of one sample during each repeat compliance period. (5) Each community and non-transient water system may apply to the State for a waiver from the requirement of paragraph (h)(4) of this section. A system must reapply for a waiver for each compliance period. (6) A State may grant a waiver after evaluating the following factor(s): Knowledge of previous use (including transport, storage, or disposal) of the contaminant within the watershed or zone of influence of the system. If a determination by the State reveals no previous use of the contaminant within the watershed or zone of influence, a waiver may be granted. If previous use of the contaminant is unknown or it has been used previously, then the following factors shall be used to determine whether a waiver is granted. (i) Previous analytical results. (ii) The proximity of the system to a potential point or non-point source of contamination. Point sources include spills and leaks of chemicals at or near a water treatment facility or at manufacturing, distribution, or storage facilities, or from hazardous and municipal waste landfills and other waste handling or treatment facilities. Non- point sources include the use of pesticides to control insect and weed pests on agricultural areas, forest lands, home and gardens, and other land application uses. (iii) The environmental persistence and transport of the pesticide or PCBs. [[Page 369]] (iv) How well the water source is protected against contamination due to such factors as depth of the well and the type of soil and the integrity of the well casing. (v) Elevated nitrate levels at the water supply source. (vi) Use of PCBs in equipment used in the production, storage, or distribution of water (i.e., PCBs used in pumps, transformers, etc.). (7) If an organic contaminant listed in Sec. 141.61(c) is detected (as defined by paragraph (h)(18) of this section) in any sample, then: (i) Each system must monitor quarterly at each sampling point which resulted in a detection. (ii) The State may decrease the quarterly monitoring requirement specified in paragraph (h)(7)(i) of this section provided it has determined that the system is reliably and consistently below the maximum contaminant level. In no case shall the State make this determination unless a groundwater system takes a minimum of two quarterly samples and a surface water system takes a minimum of four quarterly samples. (iii) After the State determines the system is reliably and consistently below the maximum contaminant level the State may allow the system to monitor annually. Systems which monitor annually must monitor during the quarter that previously yielded the highest analytical result. (iv) Systems which have 3 consecutive annual samples with no detection of a contaminant may apply to the State for a waiver as specified in paragraph (h)(6) of this section. (v) If monitoring results in detection of one or more of certain related contaminants (aldicarb, aldicarb sulfone, aldicarb sulfoxide and heptachlor, heptachlor epoxide), then subsequent monitoring shall analyze for all related contaminants. (8) Systems which violate the requirements of Sec. 141.61(c) as determined by paragraph (h)(11) of this section must monitor quarterly. After a minimum of four quarterly samples show the system is in compliance and the State determines the system is reliably and consistently below the MCL, as specified in paragraph (h)(11) of this section, the system shall monitor at the frequency specified in paragraph (h)(7)(iii) of this section. (9) The State may require a confirmation sample for positive or negative results. If a confirmation sample is required by the State, the result must be averaged with the first sampling result and the average used for the compliance determination as specified by paragraph (h)(11) of this section. States have discretion to delete results of obvious sampling errors from this calculation. (10) The State may reduce the total number of samples a system must analyze by allowing the use of compositing. Composite samples from a maximum of five sampling points are allowed, provided that the detection limit of the method used for analysis is less than one-fifth of the MCL. Compositing of samples must be done in the laboratory and analyzed within 14 days of sample collection. (i) If the concentration in the composite sample detects one or more contaminants listed in Sec. 141.61(c), then a follow-up sample must be taken within 14 days at each sampling point included in the composite, and be analyzed for that contaminant. (ii) If duplicates of the original sample taken from each sampling point used in the composite sample are available, the system may use these instead of resampling. The duplicates must be analyzed and the results reported to the State within 14 days after completion of the composite analysis or before the holding time for the initial sample is exceeded whichever is sooner. (iii) If the population served by the system is 3,300 persons, then compositing may only be permitted by the State at sampling points within a single system. In systems serving [le] 3,300 persons, the State may permit compositing among different systems provided the 5- sample limit is maintained. (11) Compliance with Sec. 141.61(c) shall be determined based on the analytical results obtained at each sampling point. (i) For systems which are conducting monitoring at a frequency greater than annual, compliance is determined by a running annual average of all samples [[Page 370]] taken at each sampling point. If the annual average of any sampling point is greater than the MCL, then the system is out of compliance. If the initial sample or a subsequent sample would cause the annual average to be exceeded, then the system is out of compliance immediately. Any samples below the detection limit shall be calculated as zero for purposes of determining the annual average. (ii) If monitoring is conducted annually, or less frequently, the system is out of compliance if the level of a contaminant at any sampling point is greater than the MCL. If a confirmation sample is required by the State, the determination of compliance will be based on the average of two samples. (12) [Reserved] (13) Analysis for PCBs shall be conducted as follows using the methods in paragraph (e) of this section: (i) Each system which monitors for PCBs shall analyze each sample using either Method 508.1, 525.2, 508 or 505. Users of Method 505 may have more difficulty in achieving the required Aroclor detection limits than users of Methods 508.1, 525.2 or 508. (ii) If PCBs (as one of seven Aroclors) are detected (as designated in this paragraph) in any sample analyzed using Method 505 or 508, the system shall reanalyze the sample using Method 508A to quantitate PCBs (as decachlorobiphenyl). ------------------------------------------------------------------------ Detection limit Aroclor (mg/l) ------------------------------------------------------------------------ 1016................................................. 0.00008 1221................................................. 0.02 1232................................................. 0.0005 1242................................................. 0.0003 1248................................................. 0.0001 1254................................................. 0.0001 1260................................................. 0.0002 ------------------------------------------------------------------------ (iii) Compliance with the PCB MCL shall be determined based upon the quantitative results of analyses using Method 508A. (14) If monitoring data collected after January 1, 1990, are generally consistent with the requirements of Sec. 141.24(h), then the State may allow systems to use that data to satisfy the monitoring requirement for the initial compliance period beginning January 1, 1993. (15) The State may increase the required monitoring frequency, where necessary, to detect variations within the system (e.g., fluctuations in concentration due to seasonal use, changes in water source). (16) The State has the authority to determine compliance or initiate enforcement action based upon analytical results and other information compiled by their sanctioned representatives and agencies. (17) Each public water system shall monitor at the time designated by the State within each compliance period. (18) Detection as used in this paragraph shall be defined as greater than or equal to the following concentrations for each contaminant. ------------------------------------------------------------------------ Detection Contaminant limit (mg/ l) ------------------------------------------------------------------------ Alachlor................................................... .0002 Aldicarb................................................... .0005 Aldicarb sulfoxide......................................... .0005 Aldicarb sulfone........................................... .0008 Atrazine................................................... .0001 Benzo[a]pyrene............................................. .00002 Carbofuran................................................. .0009 Chlordane.................................................. .0002 Dalapon.................................................... .001 1,2-Dibromo-3-chloropropane (DBCP)......................... .00002 Di (2-ethylhexyl) adipate.................................. .0006 Di (2-ethylhexyl) phthalate................................ .0006 Dinoseb.................................................... .0002 Diquat..................................................... .0004 2,4-D...................................................... .0001 Endothall.................................................. .009 Endrin..................................................... .00001 Ethylene dibromide (EDB)................................... .00001 Glyphosate................................................. .006 Heptachlor................................................. .00004 Heptachlor epoxide......................................... .00002 Hexachlorobenzene.......................................... .0001 Hexachlorocyclopentadiene.................................. .0001 Lindane.................................................... .00002 Methoxychlor............................................... .0001 Oxamyl..................................................... .002 Picloram................................................... .0001 Polychlorinated biphenyls (PCBs) (as decachlorobiphenyl)... .0001 Pentachlorophenol.......................................... .00004 Simazine................................................... .00007 Toxaphene.................................................. .001 2,3,7,8-TCDD (Dioxin)...................................... .000000005 2,4,5-TP (Silvex).......................................... .0002 ------------------------------------------------------------------------ (19) Anaylsis under this section shall only be conducted by laboratories that have received certification by EPA or the State and have met the following conditions: (i) To receive certification to conduct analyses for the contaminants in Sec. 141.61(c) the laboratory must: (A) Analyze Performance Evaluation (PE) samples provided by EPA, the [[Page 371]] State, or by a third party (with the approval of the State or EPA) at least once a year by each method for which the laboratory desires certification. (B) For each contaminant that has been included in the PE sample achieve quantitative results on the analyses that are within the following acceptance limits: ------------------------------------------------------------------------ Contaminant Acceptance limits (percent) ------------------------------------------------------------------------ DBCP...................................... 40 EDB....................................... 40. Alachlor.................................. 45. Atrazine.................................. 45. Benzo[a]pyrene............................ 2 standard deviations. Carbofuran................................ 45. Chlordane................................. 45. Dalapon................................... 2 standard deviations. Di(2-ethylhexyl)adipate................... 2 standard deviations. Di(2-ethylhexyl)phthalate................. 2 standard deviations. Dinoseb................................... 2 standard deviations. Diquat.................................... 2 standard deviations. Endothall................................. 2 standard deviations. Endrin.................................... 30. Glyphosate................................ 2 standard deviations. Heptachlor................................ 45. Heptachlor epoxide........................ 45. Hexachlorobenzene......................... 2 standard deviations. Hexachloro- cyclopentadiene 2 standard deviations. Lindane................................... 45. Methoxychlor.............................. 45. Oxamyl.................................... 2 standard deviations. PCBs (as Decachlorobiphenyl) 0-200. Picloram.................................. 2 standard deviations. Simazine.................................. 2 standard deviations. Toxaphene................................. 45. Aldicarb.................................. 2 standard deviations. Aldicarb sulfoxide........................ 2 standard deviations. Aldicarb sulfone.......................... 2 standard deviations. Pentachlorophenol......................... 50. 2,3,7,8-TCDD (Dioxin)..................... 2 standard deviations. 2,4-D..................................... 50. 2,4,5-TP (Silvex)......................... 50. ------------------------------------------------------------------------ (ii) [Reserved] (Approved by the Office of Management and Budget under control number 2040-0090) [40 FR 59570, Dec. 24, 1975, as amended at 44 FR 68641, Nov. 29, 1979; 45 FR 57345, Aug. 27, 1980; 47 FR 10998, Mar. 12, 1982; 52 FR 25712, July 8, 1987; 53 FR 5147, Feb. 19, 1988; 53 FR 25110, July 1, 1988; 56 FR 3583, Jan. 30, 1991; 56 FR 30277, July 1, 1991; 57 FR 22178, May 27, 1992; 57 FR 31841, July 17, 1992; 59 FR 34323, July 1, 1994; 59 FR 62468, Dec. 5, 1994; 60 FR 34085, June 29, 1995; 64 FR 67464, Dec. 1, 1999; 65 FR 26022, May 4, 2000] Effective Date Note: At 66 FR 7063, Jan. 22, 2001, Sec. 141.24 was amended by adding a new sentence to the end of paragraph (f)(15) introductory text; revising paragraphs (f)(15)(i) and (f)(15)(ii) and adding new paragraphs (f)(15)(iii) through (f)(15)(v); adding paragraph (f)(22); adding a new sentence to the end of paragraph (h)(11) introductory text; revising paragraphs (h)(11)(i) and (h)(11)(ii) and adding new paragraphs (h)(11)(iii) through (h)(11)(v); and adding paragraph (h)(20), effective Mar. 23, 2001, except for the amendments to (f)(15), (h)(11), and (h)(20), which are effective Jan. 22, 2004. At 66 FR 16134, Mar. 23, 2001, the effective date was delayed until May 22, 2001. At 66 FR 28350, May 22, 2001, the effective date of (f)(22) was also delayed until Jan. 22, 2004. For the convenience of the user, the revised and added text is set forth as follows: Sec. 141.24 Organic chemicals other than total trihalomethanes, sampling and analytical methods. (f) * * * (15) * * * If one sampling point is in violation of an MCL, the system is in violation of the MCL. (i) For systems monitoring more than once per year, compliance with the MCL is determined by a running annual average at each sampling point. (ii) Systems monitoring annually or less frequently whose sample result exceeds the MCL must begin quarterly sampling. The system will not be considered in violation of the MCL until it has completed one year of quarterly sampling. (iii) If any sample result will cause the running annual average to exceed the MCL at any sampling point, the system is out of compliance with the MCL immediately. (iv) If a system fails to collect the required number of samples, compliance will be based on the total number of samples collected. (v) If a sample result is less than the detection limit, zero will be used to calculate the annual average. * * * * * (22) All new systems or systems that use a new source of water that begin operation after January 22, 2004 must demonstrate compliance with the MCL within a period of time specified by the State. The system must also comply with the initial sampling frequencies specified by the State to ensure a system can demonstrate compliance with the MCL. Routine and increased monitoring frequencies shall be conducted in accordance with the requirements in this section. * * * * * (h) * * * (11)* * * If one sampling point is in violation of an MCL, the system is in violation of the MCL. (i) For systems monitoring more than once per year, compliance with the MCL is determined by a running annual average at each sampling point. (ii) Systems monitoring annually or less frequently whose sample result exceeds the regulatory detection level as defined by [[Page 372]] paragraph (h)(18) of this section must begin quarterly sampling. The system will not be considered in violation of the MCL until it has completed one year of quarterly sampling. (iii) If any sample result will cause the running annual average to exceed the MCL at any sampling point, the system is out of compliance with the MCL immediately. (iv) If a system fails to collect the required number of samples, compliance will be based on the total number of samples collected. (v) If a sample result is less than the detection limit, zero will be used to calculate the annual average. * * * * * (20) All new systems or systems that use a new source of water that begin operation after January 22, 2004 must demonstrate compliance with the MCL within a period of time specified by the State. The system must also comply with the initial sampling frequencies specified by the State to ensure a system can demonstrate compliance with the MCL. Routine and increased monitoring frequencies shall be conducted in accordance with the requirements in this section.