179 Neb. Admin. Code, ch. 13, § 007

Current through September 17, 2024

Section 179-13-007 - ANALYTICAL AND MONITORING REQUIREMENTS

007.01 Analytical Requirements

Only the analytical method(s) specified in 179 NAC 13-007 can be used to demonstrate compliance with the requirements of 179 NAC 13-004, 13-005, and 13-006. Measurements for pH, temperature, turbidity, and residual disinfectant concentrations must be conducted by a Grade I, II, III, or IV operator or a person who has been trained to take the samples. Attachment 4 (which is hereby incorporated by reference), which states that the person taking the samples has been trained to take them, must be completed, dated, and signed by the person doing the training (a Grade I, II, III, or IV licensed water operator) as well as the person trained. That form must be sent to the Department. Measurements for total coliforms, fecal coliforms, and heterotrophic plate count (HPC) must be conducted by the Department Laboratory or an approved laboratory as required in 179 NAC 3-009. Until laboratory certification criteria are developed for the analysis of fecal coliforms and HPC, any laboratory certified for total coliforms analysis by the Department or EPA is deemed certified for fecal coliforms and HPC analysis.

13-007.01A Public water systems must conduct analysis of pH and temperature in accordance with one of the methods found in 179 NAC 3-005.11A. Public water systems must conduct analysis of total coliforms, fecal coliforms, heterotrophic bacteria, and turbidity in accordance with one of the analytical methods in 40 CFR 141.74(a)(1) or an equivalent method approved by EPA and by using analytical test procedures contained in Technical Notes on Drinking Water Methods, EPA-600/R- 94-173, October 1994, which is available at NTIS PB 95-104766.

13-007.01B Public water systems must measure residual disinfectant concentrations with one of the analytical methods in 40 CFR 141.74(a)(2) or an equivalent method approved by EPA.

007.02 Monitoring Requirements for Systems That Do Not Provide Filtration

A public water system that uses a ground water source under the direct influence of surface water and does not provide filtration treatment must begin monitoring as specified in 179 NAC 13 beginning six months after the Director determines that the ground water source is under the direct influence of surface water, unless filtration is required, in which case the Director may specify alternative monitoring requirements, as appropriate, until filtration is in place.

13-007.02A Fecal coliform or total coliform density measurements as required by 179 NAC 13-004.01A must be performed on representative source water samples immediately prior to the first or only point of disinfectant application. The owner of the system must sample for fecal or total coliforms at the following minimum frequency each week the system serves water to the public:

System size (individuals served)	Samples per week¹
500 or less	1
501 to 3,300	2
3,301 to 10,000	3
10,001 to 25,000	4
Over 25,000	5

¹Must be taken on separate days

Also, one fecal or total coliform density measurement must be made every day the system serves water to the public and the turbidity of the source water exceeds 1 NTU (these samples count toward the weekly coliform sampling requirement) unless the Director determines that the system, for logistical reasons outside the system's control, cannot have the sample analyzed within 30 hours of collection.

13-007.02B Turbidity measurements as required by 179 NAC 13-004.01B must be performed on representative grab samples of source water immediately prior to the first or only point of disinfectant application every four hours (or more frequently) that the system serves water to the public. A public water system owner may substitute continuous turbidity monitoring for grab sample monitoring if it validates the continuous measurement for accuracy on a regular basis.

13-007.02C The total inactivation ratio for each day that the system is in operation must be determined based on the CT_{( 99.9)} values in Tables 13.1 through 13.8 of 179 NAC 13-007. The parameters necessary to determine the total inactivation ratio must be monitored as follows:

*These CT values achieve greater than a 99.99% inactivation of viruses. CT values between the indicated pH values may be determined by linear interpolation. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT( 99.9) value at the lower temperature and at the higher pH.

TABLE 13.2

CT VALUES [CT_{( 99.9)}] for 99.9% INACTIVATION OF GIARDIA LAMBLIA CYSTS BY FREE CHLORINE AT 5.0°C *

pH
Residual mg/l	<6.0	6.5	7.0	7.5	8.0	8.5	<9.0
< 0.4	97	117	139	166	198	236	279
0.6	100	120	143	171	204	244	291
0.8	103	122	146	175	210	252	301
1.0	105	125	149	179	216	260	312
1.2	107	127	152	183	221	267	320
1.4	109	130	155	187	227	274	329
1.6	111	132	158	192	232	281	337
1.8	114	135	162	196	238	287	345
2.0	116	138	165	200	243	294	353
2.2	118	140	169	204	248	300	361
2.4	120	143	172	209	253	306	368
2.6	122	146	175	213	258	312	375
2.8	124	148	178	217	263	318	382
3.0	126	151	182	221	268	324	389

TABLE 13.3

CT VALUES [CT_{( 99.9)}] for 99.9% INACTIVATION OF GIARDIA LAMBLIA CYSTS BY FREE CHLORINE AT 10.0°C *

pH
Residual mg/l	<6.0	6.5	7.0	7.5	8.0	8.5	<9.0
<0.4	73	88	104	125	149	177	209
0.6	75	90	107	128	153	183	218
0.8	78	92	110	131	158	189	226
1.0	79	94	112	134	162	195	234
1.2	80	95	114	137	166	200	240
1.4	82	98	116	140	170	206	247
1.6	83	99	119	144	174	211	253
1.8	86	101	122	147	179	215	259
2.0	87	104	124	150	182	221	265
2.2	89	105	127	153	186	225	271
2.4	90	107	129	157	190	230	276
2.6	92	110	131	160	194	234	281
2.8	93	111	134	163	197	239	287
3.0	95	113	137	166	201	243	292

TABLE 13.4

CT VALUES [CT_{( 99.9)}] for 99.9% INACTIVATION OF GIARDIA LAMBLIA CYSTS BY FREE CHLORINE AT 15.0°C *

pH
Residual mg/l	<6.0	6.5	7.0	7.5	8.0	8.5	<9.0
<0.4	49	59	70	83	99	118	140
0.6	50	60	72	86	102	122	146
0.8	52	61	73	88	105	126	151
1.0	53	63	75	90	108	130	156
1.2	54	64	76	92	111	134	160
1.4	55	65	78	94	114	137	165
1.6	56	66	79	96	116	141	169
1.8	57	68	81	98	119	144	173
2.0	58	69	83	100	122	147	177
2.2	59	70	85	102	124	150	181
2.4	60	72	86	105	127	153	184
2.6	61	73	88	107	129	156	188
2.8	62	74	89	109	132	159	191
3.0	63	76	91	111	134	162	195

TABLE 13.5

CT VALUES [CT_{( 99.9)}] for 99.9% INACTIVATION OF GIARDIA LAMBLIA CYSTS BY FREE CHLORINE AT 20.0°C *

pH
Residual mg/l	<6.0	6.5	7.0	7.5	8.0	8.5	<9.0
<0.4	36	44	52	62	74	89	105
0.6	38	45	54	64	77	92	109
0.8	39	46	55	66	79	95	113
1.0	39	47	56	67	81	98	117
1.2	40	48	57	69	83	100	120
1.4	41	49	58	70	85	103	123
1.6	42	50	59	72	87	105	126
1.8	43	51	61	74	89	108	129
2.0	44	52	62	75	91	110	132
2.2	44	53	63	77	93	113	135
2.4	45	54	65	78	95	115	138
2.6	46	55	66	80	97	117	141
2.8	47	56	67	81	99	119	143
3.0	47	57	68	83	101	122	146

TABLE 13.6

CT VALUES [CT_{( 99.9)}] for 99.9% INACTIVATION OF GIARDIA LAMBLIA CYSTS BY FREE CHLORINE AT 25.0°C AND HIGHER*

pH
Residual mg/l	<6.0	6.5	7.0	7.5	8.0	8.5	<9.0
<0.4	24	29	35	42	50	59	70
0.6	25	30	36	43	51	61	73
0.8	26	31	37	44	53	63	75
1.0	26	31	37	45	54	65	78
1.2	27	32	38	46	55	67	80
1.4	27	33	39	47	57	69	82
1.6	28	33	40	48	58	70	84
1.8	29	34	41	49	60	72	86
2.0	29	35	41	50	61	74	88
2.2	30	35	42	51	62	75	90
2.4	30	36	43	52	63	77	92
2.6	31	37	44	53	65	78	94
2.8	31	37	45	54	66	80	96
3.0	32	38	46	55	67	81	97

TABLE 13.7

CT VALUES [CT_{( 99.9)}] for 99.9% INACTIVATION OF GIARDIA LAMBLIA CYSTS BY CHLORINE DIOXIDE AND OZONE*

Temperature

<1°C	5°C	10°C	15°C	20°C	25°C
Chlorine dioxide	63	26	23	19	15	11
Ozone	2.9	1.9	1.4	0.95	0.72	0.48

*These CT values achieve greater than a 99.99% inactivation of viruses. CT values between the indicated temperatures of different tables may be determined by linear interpolation. If no interpolation is used, use the CT( 99.9) value at the lower temperature and at the higher pH.

TABLE 13.8

CT VALUES [CT_{( 99.9)}] for 99.9% INACTIVATION OF GIARDIA LAMBLIA CYSTS BY CHLORAMINES*

Temperature

<1°C	5°C	10°C	15°C	20°C	25°C
Chloramine	3,800	2,200	1,850	1,500	1,100	750

*These values are for pH values of 6 to 9. These CT values may be assumed to achieve greater than 99.99% inactivation of viruses only if chlorine is added and mixed in the water prior to the addition of ammonia. If this condition is not met, the system must demonstrate, in accordance with 179 NAC 13-006, that the system is achieving at least 99.99% inactivation of viruses. CT values between the indicated temperatures may be determined by linear interpolation. If no interpolation is used, use the CT( 99.9) value at the lower temperature for determining CT( 99.9) values between indicated temperatures.

13-007.02C1 The temperature of the disinfected water must be measured at least once per day at each residual disinfectant concentration sampling point.

13-007.02C2 If the system uses chlorine, the pH of the disinfected water must be measured at least once per day at each chlorine residual disinfectant concentration sampling point.

13-007.02C3 The disinfectant contact time(s) ("T") must be determined for each day during peak hourly flow.

13-007.02C4 The residual disinfectant concentration(s) ("C") of the water before or at the first customer must be measured each day during peak hourly flow.

13-007.02C5 If a system uses a disinfectant other than chlorine, the system may demonstrate to the Director that CT_{( 99.9)} values other than those specified in Tables 13.7 and 13.8 in 179 NAC 13-007 or other operational parameters are adequate to demonstrate that the system is achieving the minimum inactivation rates required by 179 NAC 13-005.

TABLE 13.1

CT VALUES [CT_{( 99.9)}] for 99.9% INACTIVATION OF GIARDIA LAMBLIA CYSTS BY FREE CHLORINE AT 0.5°C OR LOWER*

pH
Residual mg/l	<6.0	6.5	7.0	7.5	8.0	8.5	<9.0
<0.4	137	163	195	237	277	329	390
0.6	141	168	200	239	286	342	407
0.8	145	172	205	246	295	354	422
1.0	148	176	210	253	304	365	437
1.2	152	180	215	259	313	376	451
1.4	155	184	221	266	321	387	464
1.6	157	189	226	273	329	397	477
1.8	162	193	231	279	338	407	489
2.0	165	197	236	286	346	417	500
2.2	169	201	242	297	353	426	511
2.4	172	205	247	298	361	435	522
2.6	175	209	252	304	368	444	533
2.8	178	213	257	310	375	452	543
3.0	181	217	261	316	382	460	552

13-007.02D The total inactivation ratio must be calculated as follows:

13-007.02D1 If the system uses only one point of disinfectant application, the system owner may determine the total inactivation ratio based on either of the following two methods:

1. One inactivation ratio [CTcalc divided by CT_{( 99.9)}] is determined before or at the first customer during peak hourly flow and if CTcalc divided by CT_{( 99.9)} is greater than or equal to 1.0, the 99.9% Giardia lamblia inactivation requirement has been achieved; or

2. Successive CTcalc divided by CT_{( 99.9)} values, representing sequential inactivation ratios, are determined between the point of disinfectant application and a point before or at the first customer during peak hourly flow. Under this alternative, the following method must be used to calculate the total inactivation ratio:

a. Determine CTcalc divided by CT_{( 99.9)} for each sequence;

b. Add the CTcalc divided by CT_{( 99.9)} values together; and

c. If the sum of CTcalc divided by CT_{( 99.9)} is greater than or equal to 1.0, the 99.9% Giardia lamblia inactivation requirement has been achieved.

13-007.02D2 If the system used more than one point of disinfectant application before or at the first customer, the system owner must determine the CT value of each disinfection sequence immediately prior to the next point of disinfectant application during peak hourly flow. The CTcalc divided by CT_{( 99.9)} value of each sequence and the sum of CTcalc divided by CT_{( 99.9)} must be calculated using the method in 179 NAC 13-007.02D1 item 2 to determine if the system is in compliance with 179 NAC 13-005.01.

13-007.02D3 Although not required, the total percent inactivation for a system with one or more points of residual disinfectant concentration monitoring may be calculated by solving the following equation:

Percent inactivation = 100 - 100 divided by 10^Z

Where: Z = 3 times the sum of CTcalc divided by CT_{( 99.9)}

13-007.02E The residual disinfectant concentration of the water entering the distribution system must be monitored continuously, and the lowest value must be recorded each day, except that if there is a failure in the continuous monitoring equipment, grab sampling every four hours may be conducted in lieu of continuous monitoring, but for no more than five working days following the failure of the equipment. Owners of systems serving 3,300 or fewer individuals may take grab samples in lieu of providing continuous monitoring on an ongoing basis at the frequencies prescribed below:

System size by population	Samples per day¹
500 or less	1
501 to 1,000	2
1,001 to 2,500	3
2,501 to 3,300	4

¹The day's samples cannot be taken at the same time. The sampling intervals are subject to review and approval by the Director.

If at any time the residual disinfectant concentration falls below 0.2 mg per liter in a system using grab sampling in lieu of continuous monitoring, the system must take a grab sample every four hours until the residual concentration is equal to or greater than 0.2 mg per liter.

13-007.02FMeasurement of Residual Disinfectant

13-007.02F1 Through March 31, 2016, the residual disinfectant concentration must be measured at least at the same points in the distribution system and at the same time as total coliforms are sampled, as specified in 179 NAC 3-004. Beginning April 1, 2016, the residual disinfectant concentration must be measured at least at the same points in the distribution system and at the same time as total coliforms are sampled, as specified in 179 NAC 26-006 through 26-010. The Director may allow a public water system which uses both a surface water source or a ground water source under the direct influence of surface water, and a ground water source to take disinfectant residual samples at points other than the total coliform sampling points if the Director determines that such points are more representative of treated (disinfected) water quality within the distribution system. Heterotrophic bacteria measured as heterotrophic plate count (HPC) as specified in 179 NAC 13-007.01A may be measured in lieu of residual disinfectant concentration.

13-007.02F2 If the Director determines, based on site-specific considerations, that a system has no means for having a sample transported and analyzed for HPC by an approved laboratory under the requisite time and temperature conditions required of the approved laboratory, and that the system is providing adequate disinfection in the distribution system, the requirements of 179 NAC 13-007.02F1 do not apply to that system.

007.03 Monitoring Requirements for Systems Using Filtration Treatment

A public water system that uses a surface water source or a ground water source under the influence of surface water and provides filtration treatment must monitor in accordance with 179 NAC 13-007 beginning June 29, 1993, or when filtration is installed, whichever is later.

13-007.03A Turbidity measurements as required by 179 NAC 13-006 must be performed on representative samples of the system's filtered water every four hours (or more frequently) that the system serves water to the public. A public water system owner may substitute continuous turbidity monitoring for grab sample monitoring if the owner validates the continuous measurement for accuracy on a regular basis. For any systems using slow sand filtration or filtration treatment other than conventional treatment, direct filtration, or diatomaceous earth filtration, the Director may reduce the sampling frequency to once per day if the Director determines that less frequent monitoring is sufficient to indicate effective filtration performance. For systems serving 500 or fewer individuals, the Director may reduce the turbidity sampling frequency to once per day, regardless of the type of filtration treatment used, if the Director determines that less frequent monitoring is sufficient to indicate effective filtration performance.

13-007.03B The residual disinfectant concentration of the water entering the distribution system must be monitored continuously, and the lowest value must be recorded each day, except that if there is a failure in the continuous monitoring equipment, grab sampling every four hours may be conducted in lieu of continuous monitoring, but for no more than five working days following the failure of the equipment. Owners of systems serving 3,300 or fewer individuals may take grab samples in lieu of providing continuous monitoring on an ongoing basis at the frequencies each day prescribed below:

System size by population	Samples per day¹
500 or less	1
501 to 1,000	2
1,001 to 2,500	3
2,501 to 3,300	4

¹The day's samples cannot be taken at the same time. The sampling intervals are subject to review and approval by the Director.

13-007.03CMeasurement of Residual Disinfectant: Through March 31, 2016, the residual disinfectant concentration must be measured at least at the same points in the distribution system and at the same time as total coliforms are sampled, as specified in 179 NAC 3-004.01B. Beginning April 1, 2016, the residual disinfectant concentration must be measured at least at the same points in the distribution system and at the same time as total coliforms are sampled, as specified in 179 NAC 26-006 through 26-010. The Director may allow a public water system which uses both a surface water source or a ground water source under the direct influence of surface water, and a ground water source to take disinfectant residual samples at points other than the total coliform sampling points if the Director determines that such points are more representative of treated (disinfected) water quality within the distribution system. Heterotrophic bacteria, measured as heterotrophic plate count (HPC) as specified in 179 NAC 13-007.01A may be measured in lieu of residual disinfectant concentration.

179 Neb. Admin. Code, ch. 13, § 007