PROPOSED RULES 11996 Minimum number of samples per month Population serbca: 320.001 360,001 to 360,000. 2-2 eee eee to 410.000... 22 ween 180 190 450,004 500,001 to SO0000_. 2-2-2220 eee 210 to §50,000...---.------------ 220 600.001 660,00 720,001 ta G6O.O00. 2.2L ~.-. 240 to 720.000. _.--2. 2.2 ---- 250 to 780,000... -.-....----.----- 260 910,001 to 970.000__....-_----_-..----- 290 970,001 to 410.001 to 150,000... .2. 222 eee 200 550,001 ta GOO.000_. owe. eee 230 780,000 ta 840,000__...-_-..--...----- 270 840,001 to 910.000... 2.2 eee 280 t,.050,000_. e 1,140,001 1,290,001 to 1,250,000. .-.-....22------- ae to 1,320,000_._...--.-----.-.--- 1,420,001 to 1,520,000_... 2.060,001 2,270,001 to 2,270,000_. to 2,510.000__ 1,320,001 to 1,420,000... to ta to to to 1,630.000__.. 1,730,000__-1,850,000_. 1,970,000__... 2,060,000___. 2,510,001 to 2,750,000_. 2,750,001 to 3,020,000_0-..-----__--.-.+- 440 3,020,001 to 3,320,000_. ---- 450 3,320,001 to 3,620,000__ -+-- 460 3,620,001 to 3,960,000_._--__.---._--.-_- 470 3,960,001 to 4,310,000_____..-- 2-1-8. 480 4,310,001 to 4,690,000_.... 022 -02--22- 490 B4,690000 wii ienee einen ne 500 (c) (1) Whenthe coliform colonies ina single standard sample exceed four per 100 milliliters (§ 141.15(a)(1)), dally samples shall be coNected and examined from the same sampling point until the results obtained from at least two consecutive samples showless than one coli- six years following the effective date of this subpart. Tnese analyses shall be repeated at five-year intervals. (b) If the supplier of water determines or has been informed by the State that the Ievel of any contaminant is 75 percent or more of the maximum contam- as prescribed in § 141.31. Also, if the non-compliance is confirmed, a sample. for coliform analysis must be immediately collected from that sampling point and the results of such analysis reported to tha Blatta. 1,050,001 to 1,140.000__ 1,520,00L 1,630,001 1,730,001 1,850,001 1,970,001 ‘tion, the supplicr of water shall report * shall be completed within two years fol‘lowing: the effective date of this subpart. as directed in § 141.32¢n), This analysis shall be repcatcd at three(1) When a particular sampling point has been shown to be in non-compliance year intervals. (3) Analyses for public water systems with the requirements of § 141.16, water from that location shall be retested other than community water systems, wiltiin one hour. If the non-compliance whether supplicd by surface or ground is confirmed, the State shall be notified water sources, shall be compicted within (g) Standard bacteria plate : count inant samples shall be analyzed in accordance level, he shail analyze for the presence and quantity of that contami- with the recommendation set forth In “Standard Methods for the Examination of Water and Wastewater,” American Public Health Association, 13th Edition, pp 660-662. Samples taken for the pur- nant at least once per month folowins the initial analysis or information. If, after conducting monthly testing for a period of at least one year, the supplicr of water demonstrates to the satisfaction pose of plate count analysis shall be collected at points which are representative: of the State that the level of such contaminant is stable and duc to a natural of conditions within the distribution system at a frequency at least equal to 10 é condition of the water source, he may repercent of the frequency for coliform an- - duce the frequency of analysis for that alysis as direcled in paragraph (b) of contaminant consistent with the requirethis section with the exception that at ments of paragraph (a) of this section. (c) If the supplier of water determines least one sample shall be collected and : ’ or has been informed by the State that analyzed monthly, A . .. a eee the level of any contaminant listed in § 141.22 Turbidity sampling and ana§ 141.11 exceeds the maximum contamlytical requirenients. inant level for the substance, he shall (a) Samples shall be taken at a repre- confirm such determination or information by repeating the analysis within 24 sentative entry point(s) to the water hours following the initial analysis or indistribution system at least’ once per day (at least once per month for sup- plies using water obtained from under- ground sources) for the purpose of making turbidity measurements to determine form per 100 milliliters. : (2) When organisms of the coliform compliance with § 141.14. The measuregroup occur in three or more 10 mi por- ment shall be made in accordance tions of a single standard sample with the recommendations set forth in (§ 141.15(a) (2) (i)), daily samples shall “Standard Methods for the Examination be collected and examined from the same of Water and .Wastewater,” American sampling point until the results obtained Public Health Association, 13th Edition, from at least two consecutive sampics ‘pp. 350-353 (Nephelometric Method). shownopositive tubes, (b) In the event that such measure(3) When organisms of the coliform ment indicates that the maximum allowgroup occur in all five of the 100 ml por- able limit has been exceeded, the samtions of a single standard sample pling and measurement shall be repeated (§ 141.15(a) (2) (ii) ), daily samples shall within one hour. The results of the two be collected and examined from the same measurements shall be averaged, and if . sampling point until the results obtained the average confirms that the maximum from at least two consecutive samples allowable limit has been exceeded, this averare shall be reported as directed in showno positive tubes. (4) The location at which the check § 141.31. If the monthly average of all sample was taken pursuant to para- samples exceeds the maximum allowable graphs (c) (1), (2) or (3) of this section limit, this fact shall be reported as dimust not be eliminated from future sam- rected in § 141.32(a). (c) The requirements of this § 141.22 pling because of a history of questionable water quality, Check samples shail not he shall not apply to public water systems formation, and then at least at weekly intervals during the period of time the maximum contaminant level for that substance has been exceeded, or until a monitoring schedule as a condition to a variance, exemption or enforcement action shall become effective. The results of _such repetitive testing shall be averaged and reported as prescribed in paragraph (d) of this section. (d) To judge the compliance of a public water system with the maximum contaminant levels listed in § 141.11, averages of data shall be used and shall be rounded to the same numberof significant figures as the maximum contaminant level for the substance in question. Each average shall be calculated on a past 12-month moving average basis if less than twelve samples per year are analyzed, and on a past three month moving average basis if twelve or more samples per year are analyzed. In cases where the maximum contaminant level has been exceeded in any one sample, the average concentration shall be calcu- other than community water systems lated on @ one-month moving average mine compliance with § 141.15. (d) When a particular sampling point , § 141.23 Inorganic chemical sampling has been confirmed, by the first check * and analytical requirements. Sample examined as directed in para- . (a) (1) To establish an initial record graphs (c) (1), (2), or (3) of this section, to be in non-compliance with the of water quality, an analysis of submaximum contaminant levels set forth stances for the purpose of determining in § 141.15, the supplier of water shall compliance with § 141.111 shall be comnotify the State as prescribed in § 141.31. pleted for all community water systems utilizing surface water sources within (e) When the maximum contaminant one year following the effective date of - levels set forth in paragraphs (a) (1) or this subpart. This analysis shall be re(2) of § 141.15 are exceeded as confirmed peated at yearly intervals. (2) An analysis for communtly water by check samples taken pursuant to paragraphs (c) (1), (2), or (3) of this sec- systems utilizing ground water sources pursuartt to § 141.32(a). (e) The provisions of pararraphs (c) and (d) of this section notwithstanding, compliance with the maximum contaminant level for nitrate shall be determincd on the basis of individual analyses rather than by averages. When a level exceeding the maximum contaminant level for nitrate is found, the analyses shall be repented within 24 hours, and if the mean ofthe two analyses excceds the included in calculating the total number of samples taken each month to deter- po2sT) basis and reported pursuant to § 141.31. If the mean of the samples comprising the one month moving average exceeds the maximum contaminant Ievel, the which use water obtained from underground sources. . supplier of water shall give public notice . | FEDERAL REGISTER, VOL. 40, NO. S1—-FRIDAY, MARCH 14, 1975