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§141.24 Organic chemicals, sampling and analytical requirements.
Link to an amendment published at 66 FR 7063, January 22, 2001.
Additional parts of this amendment were delayed until January 22, 2004 at 66 FR 28350, May 22, 2001.
(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, 1301 Constitution Avenue, NW., EPA West, Room B102, Washington DC 20460 (Telephone: 202-566-2426); 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), 19th edition (1995), or 20th edition (1998), American Public Health Association (APHA); any of these three editions may be used. Method 6610 shall be followed in accordance with Standard Methods for the Examination of Water and Wastewater, (18th Edition Supplement) (1994), or with the 19th edition (1995) or 20th edition (1998) of Standard Methods for the Examination of Water and Wastewater; any of these three editions 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, (1999), Vol. 11.02, ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428, or in any edition published after 1993. EPA Method 515.4, "Determination of Chlorinated Acids in Drinking Water by Liquid-Liquid Microextraction, Derivatization and Fast Gas Chromatography with Electron Capture Detection," Revision 1.0, April 2000, EPA /815/B-00/001 can be accessed and downloaded directly on-line at www.epa.gov/safewater/methods/sourcalt.html. The Syngenta AG-625, "Atrazine in Drinking Water by Immunoassay", February 2001 is available from Syngenta Crop Protection, Inc., 410 Swing Road, Post Office Box 18300, Greensboro, NC 27419, Phone number (336) 632-6000. Method 531.2 "Measurement of N-methylcarbamoyloximes and N-methylcarbamates in Water by Direct Aqueous Injection HPLC with Postcolumn Derivatization," Revision 1.0, September 2001, EPA 815/B/01/002 can be accessed and downloaded directly on-line at www.epa.gov/safewater/methods/sourcalt.html.
----------------------------------------------------------------------------------------------------------------
EPA method [SU]1[/
Contaminant SU] Standard methods ASTM Other
----------------------------------------------------------------------------------------------------------------
1. Benzene.......................... 502.2, 524.2.....
2. Carbon tetrachloride............. 502.2, 524.2,
551.1.
3. Chlorobenzene.................... 502.2, 524.2.....
4. 1,2-Dichlorobenzene.............. 502.2, 524.2.....
5. 1,4-Dichlorobenzene.............. 502.2, 524.2.....
6. 1,2-Dichloroethane............... 502.2, 524.2.....
7. cis-Dichloroethylene............. 502.2, 524.2.....
8. trans-Dichloroethylene........... 502.2, 524.2.....
9. Dichloromethane.................. 502.2, 524.2.....
10. 1,2-Dichloropropane............. 502.2, 524.2.....
11. Ethylbenzene.................... 502.2, 524.2.....
12. Styrene......................... 502.2, 524.2.....
13. Tetrachloroethylene............. 502.2, 524.2,
551.1.
14. 1,1,1-Trichloroethane........... 502.2, 524.2,
551.1.
15. Trichloroethylene............... 502.2, 524.2,
551.1.
16. Toluene......................... 502.2, 524.2.....
17. 1,2,4-Trichlorobenzene.......... 502.2, 524.2.....
18. 1,1-Dichloroethylene............ 502.2, 524.2.....
19. 1,1,2-Trichloroethane........... 502.2, 524.2,
551.1.
20. Vinyl chloride.................. 502.2, 524.2.....
21. Xylenes (total)................. 502.2, 524.2.....
22. 2,3,7,8-TCDD (dioxin)........... 1613.............
23. 2,4-D [SU]4[/SU] (as acid, salts 515.2, 555, ................. D5317-93.........
and esters). 515.1, 515.3,
515.4.
24. 2,4,5-TP [SU]4[/SU] (Silvex).... 515.2, 555, ................. D5317-93.........
515.1, 515.3,
515.4.
25. Alachlor [SU]2[/SU]............. 507, 525.2,
508.1, 505,
551.1.
26. Atrazine [SU]2[/SU]............. 507, 525.2, ................. ................. Syngenta AG-625.
508.1, 505,
551.1.
27. Benzo(a)pyrene.................. 525.2, 550, 550.1
28. Carbofuran...................... 531.1, 531.2..... 6610.............
29. Chlordane....................... 508, 525.2,
508.1, 505.
30. Dalapon......................... 552.1, 515.1,
552.2, 515.3,
515.4.
31. Di(2-ethylhexyl)adipate......... 506, 525.2.......
32. Di(2-ethylhexyl)phthalate....... 506, 525.2.......
33. Dibromochloropropane (DBCP)..... 504.1, 551.1.....
34. Dinoseb [SU]4[/SU].............. 515.2, 555,
515.1, 515.3,
515.4.
35. Diquat.......................... 549.2............
36. Endothall....................... 548.1............
37. Endrin.......................... 508, 525.2,
508.1, 505,
551.1.
38. Ethylene dibromide (EDB)........ 504.1, 551.1.....
39. Glyphosate...................... 547.............. 6651.............
40. Heptachlor...................... 508, 525.2,
508.1, 505,
551.1.
41. Heptachlor Epoxide.............. 508, 525.2,
508.1, 505,
551.1.
42. Hexachlorobenzene............... 508, 525.2,
508.1, 505,
551.1.
43. Hexachlorocyclopentadiene....... 508, 525.2,
508.1, 505,
551.1.
44. Lindane......................... 508, 525.2,
508.1, 505,
551.1.
45. Methoxychlor.................... 508, 525.2,
508.1, 505,
551.1.
46. Oxamyl.......................... 531.1, 531.2..... 6610.............
47. PCBs [SU]3[/SU] (as 508A.............
decachlorobiphenyl).
48. PCBs [SU]3[/SU] (as Aroclors)... 508.1, 508,
525.2, 505.
49. Pentachlorophenol............... 515.2, 525.2, ................. D5317-93.........
555, 515.1,
515.3, 515.4.
50. Picloram [SU]4[/SU]............. 515.2, 555, ................. D5317-93.........
515.1, 515.3,
515.4.
51. Simazine [SU]2[/SU]............. 507, 525.2,
508.1, 505,
551.1.
52. Toxaphene....................... 508, 508.1,
525.2, 505.
53. 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, 515.4 and 555 and ASTM Method D5317-93.
(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 §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 §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 §141.61(a) (1) through (8) and the monitoring for the contaminants listed in §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 §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 §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 §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 §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 §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 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 §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 §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 ≤ 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 °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.
(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 §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 §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 §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 §141.61(a)(2) through (21) shall begin monitoring annually in accordance 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 §141.61(c) for the purposes of
determining compliance with the maximum contaminant level shall be conducted as
follows: 7 7Monitoring for the contaminants aldicarb, aldicarb sulfoxide, and
aldicarb sulfone shall be conducted in accordance with §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 §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.
(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 §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 §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 §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 ≤ 3,300 persons, the State may permit
compositing among different systems provided the 5-sample limit is maintained.
(11) Compliance with §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
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). (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 §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. (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
§141.61(c) 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) For each contaminant that has been included in the PE sample achieve
quantitative results on the analyses that are within the following acceptance
limits: (ii) [Reserved] [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; 67 FR 65250,
Oct. 23, 2002; 67 FR 65898, Oct. 29, 2002]
------------------------------------------------------------------------
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
------------------------------------------------------------------------
------------------------------------------------------------------------
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
------------------------------------------------------------------------
------------------------------------------------------------------------
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.
------------------------------------------------------------------------
(Approved by the Office of Management and
Budget under control number 2040-0090)