Iowa Admin. Code agency 567, tit. II, div. B, ch. 43, app C

Current through Register Vol. 47, No. 11, December 11, 2024

Appendix C - CT TABLES FOR VIRUS INACTIVATION UNDER THE GROUNDWATER RULE, 567-41.7(455B)

TABLE 1: CT Values (mg-min/L) for Inactivation of Viruses by Free Chlorine, pH 6.0-9.0¹

Inactivation Log Credit	Water Temperature, °C
	1	2	3	4	5	6	7	8	9
2	5.8	5.3	4.9	4.4	4.0	3.8	3.6	3.4	3.2
3	8.7	8.0	7.3	6.7	6.0	5.6	5.2	4.8	4.4
4	11.6	10.7	9.8	8.9	8.0	7.6	7.2	6.8	6.4
1CT values provided in the table are modified by linear interpolation between 0.5°C increments.

Inactivation Log Credit	Water Temperature, °C
	10	11	12	13	14	15	16	17
2	3.0	2.8	2.6	2.4	2.2	2.0	1.8	1.6
3	4.0	3.8	3.6	3.4	3.2	3.0	2.8	2.6
4	6.0	5.6	5.2	4.8	4.4	4.0	3.8	3.6
1CT values provided in the table are modified by linear interpolation between 0.5°C increments.

TABLE 2: CT Values (mg-min/L) for Inactivation of Viruses by Free Chlorine, pH 9.1-10.0

Inactivation Log Credit	Water Temperature, °C
	18	19	20	21	22	23	24	25
2	1.4	1.2	1.0	1.0	1.0	1.0	1.0	1.0
3	2.4	2.2	2.0	1.8	1.6	1.4	1.2	1.0
4	3.4	3.2	3.0	2.8	2.6	2.4	2.2	2.0
1CT values provided in the table are modified by linear interpolation between 0.5°C increments.

TABLE 3: CT Values (mg-min/L) for Inactivation of Viruses by Chlorine Dioxide, pH 6.0-9.0¹

Inactivation Log Credit	Water Temperature, °C
	0.5	5	10	15	20	25
2	45	30	22	15	11	7
3	66	44	33	22	16	11
4	90	60	45	30	22	15

Inactivation Log Credit	Water Temperature, °C
	1	2	3	4	5	6	7	8	9
2	8.4	7.7	7.0	6.3	5.6	5.3	5.0	4.8	4.5
3	25.6	23.5	21.4	19.2	17.1	16.2	15.4	14.5	13.7
4	50.1	45.9	41.8	37.6	33.4	31.7	30.1	28.4	26.8
1CT values provided in the table are modified by linear interpolation between 0.5°C increments.

Inactivation Log Credit	Water Temperature, °C
	10	11	12	13	14	15	16	17
2	4.2	3.9	3.6	3.4	3.1	2.8	2.7	2.5
3	12.8	12.0	11.1	10.3	9.4	8.6	8.2	7.7
4	25.1	23.4	21.7	20.1	18.4	16.7	15.9	15.0
1CT values provided in the table are modified by linear interpolation between 0.5°C increments.

Inactivation Log Credit	Water Temperature, °C
	18	19	20	21	22	23	24	25
2	2.4	2.2	2.1	2.0	1.8	1.7	1.5	1.4
3	7.3	6.8	6.4	6.0	5.6	5.1	4.7	4.3
4	14.2	13.3	12.5	11.7	10.9	10.0	9.2	8.4
1CT values provided in the table are modified by linear interpolation between 0.5°C increments.

TABLE 4: CT Values (mg-min/L) for Inactivation of Viruses by Ozone¹

Inactivation Log Credit	Water Temperature, °C
	1	2	3	4	5	6	7	8	9
2	0.90	0.83	0.75	0.68	0.60	0.58	0.56	0.54	0.52
3	1.40	1.28	1.15	1.03	0.90	0.88	0.86	0.84	0.82
4	1.80	1.65	1.50	1.35	1.20	1.16	1.12	1.08	1.04
1CT values provided in the table are modified by linear interpolation between 0.5°C increments.

Inactivation Log Credit	Water Temperature, °C
	10	11	12	13	14	15	16	17
2	0.50	0.46	0.42	0.38	0.34	0.30	0.29	0.28
3	0.80	0.74	0.68	0.62	0.56	0.50	0.48	0.46
4	1.00	0.92	0.84	0.76	0.68	0.60	0.58	0.56
1CT values provided in the table are modified by linear interpolation between 0.5°C increments.

Inactivation Log Credit	Water Temperature, °C
	18	19	20	21	22	23	24	25
2	0.27	0.26	0.25	0.23	0.21	0.19	0.17	0.15
3	0.44	0.42	0.40	0.37	0.34	0.31	0.28	0.25
4	0.54	0.52	0.50	0.46	0.42	0.38	0.34	0.30
1CT values provided in the table are modified by linear interpolation between 0.5°C increments.

No CT table is provided for chloramines or total chlorine because the CT values would be prohibitively high for groundwater systems.

Tables are from the EPA Groundwater Rule Implementation Guidance, EPA 816-R-09-004, January 2009, pages 97-98.

Iowa Admin. Code agency 567, tit. II, div. B, ch. 43, app C

Adopted by IAB April 11, 2018/Volume XL, Number 21, effective 5/16/2018