Administrative Code

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Virginia Administrative Code
Title 12. Health
Agency 5. Department of Health
Chapter 590. Waterworks Regulations
6/30/2022

12VAC5-590-500. Disinfection criteria, determination of CT, disinfection profiles, and disinfection benchmarks for Giardia and virus inactivation.

A. A waterworks utilizing surface water sources or GUDI sources, in whole or in part, shall be disinfected in accordance with subsection C of this section and 12VAC5-590-1000.

B. The owner of a groundwater system subject to the requirements of 12VAC5-590-421 A 1 d shall provide primary disinfection treatment by means of one of the following:

1. A residual disinfectant concentration (C) and contact time (T) to achieve a 4-log removal or inactivation of viruses. CT shall be calculated in accordance with subsections C and D of this section, which contain information on calculation methods and contact tank baffling factors.

2. UV treatment to achieve a 4-log removal or inactivation of viruses. Log inactivation shall be determined in accordance with 12VAC5-590-401 E 7 c. A secondary disinfection residual in the distribution system may be required by the department.

C. Disinfection criteria.

1. An owner of a waterworks utilizing surface water sources, in whole or in part, or GUDI sources shall provide a minimum 3-log (99.9%) removal of Giardia cysts and a 4-log (99.99%) removal of viruses, respectively.

2. Additional inactivation levels that must be achieved by disinfection shall be in accordance with Table 500.1 for waterworks employing the filtration processes listed.

TABLE 500.1
Maximum Log Removal Credits for Various Filtration Technologies and the Resulting Minimum Required Logs of Inactivation by Disinfection

FILTRATION PROCESSa

MAXIMUM LOG REMOVAL CREDITS FOR FILTRATION

ADDITIONAL LOG INACTIVATION REQUIRED BY DISINFECTION

Giardia lamblia

Viruses

Giardia lamblia

Viruses

Conventional

2.5

2.0

0.5

2.0

Direct

2.0

1.0

1.0

3.0

Pre-engineered package

2.5

Zero

0.5

4.0

Diatomaceous Earth

2.0

1.0

1.0

3.0

Slow Sand

2.0

2.0

1.0

2.0

Membrane (MF or UF)

3.0

Zero

0.5

4.0

Bag or Cartridge

2.0

Zero

1.0

4.0

aRefer to Part III of this chapter for further description of the filtration processes.

D. A disinfection profile shall be developed in accordance with the procedures in subdivisions D 1, D 2, and D 3.

1. The owner shall monitor at least weekly for a period of 12 consecutive months to determine the total log inactivation for Giardia lamblia and viruses. If an owner monitors more frequently, then the monitoring frequency shall be evenly spaced. An owner of a waterworks that operates for fewer than 12 months per year shall monitor weekly during the period of operation.

2. The owner of a waterworks with a single point of disinfectant application before the entrance to the distribution system or with more than one point of disinfectant application shall conduct the monitoring in subdivisions D 2 a through D 2 e of this section.

a. For a waterworks using a disinfectant other than UV, the temperature of the disinfected water shall be measured at each residual disinfectant concentration sampling point during peak hourly flow or at an alternative location approved by the department.

b. For a waterworks using chlorine, the pH of the disinfected water shall be measured at each chlorine residual disinfectant concentration sampling point during peak hourly flow or at an alternative location approved by the department.

c. The residual disinfectant concentration (C) of the water before or at the first customer and before each additional point of disinfectant application shall be measured at peak hourly flow.

d. The disinfectant contact times (T) of the water before or at the first customer and before each additional point of disinfectant application shall be determined during peak hourly flow. The disinfectant contact time to be used for calculating CT is T10, which is the detention time at which 90% of the water passing through a unit is retained within that unit. T10 shall be determined either by calculations that involve the theoretical hydraulic detention time and baffling factors that account for the degree of short-circuiting that might be expected through any given unit or by tracer studies. The baffling factors listed in Table 500.15 shall be used in determining contact time if tracer studies are not performed.

e. Inactivation credits for ozone contactors will be based on only the chambers that have a measured ozone residual. A minimum of two dedicated online monitors per ozone contactor shall be installed at locations suited to the CT calculation method used. Ozone residual levels shall be monitored continuously and recorded. Methods for computing log inactivation of Giardia lamblia and virus shall be approved by the department. Tracer studies shall be required to verify T10 values before receiving inactivation credit.

3. Instead of conducting new monitoring under subdivision D 2 of this section, an owner may elect to meet the requirements of subdivision D 3 a or D 3 b of this section.

a. The owner who has at least one year of existing data that are substantially equivalent to data collected under the provisions of subdivision D 3 of this section shall use these data to develop disinfection profiles if the owner has neither made a significant change to the treatment practice nor changed sources since the data were collected. The owner may develop a disinfection profile using up to three years of existing data.

b. The owner may use a disinfection profile developed previously in accordance with the procedures in subdivisions D 1, D 2, and D 3 of this section, if the owner has neither made a change to the treatment practice nor changed sources since the profile was developed. An owner that has not developed a virus profile shall develop a virus disinfection profile using the same monitoring data on which the Giardia lamblia profile is based.

E. The owner shall calculate the total inactivation ratio for Giardia lamblia and viruses as specified in subdivisions E 1 through E 4 of this subsection based on CT99.9 (3-log) values using the appropriate values in Tables 500.2 through 500.14. Note that the 3-log values in the tables for Giardia lamblia also indicate that a 4-log virus inactivation can be achieved. pH and temperature values between the indicated values in Tables 500.2 through 500.14 shall be determined by linear interpolation, or the CT value at the lower temperature and at the higher pH shall be used. All parameters necessary to determine the total inactivation ratio shall be monitored during peak hourly flow.

1. The owner using only one point of disinfectant application shall determine the total inactivation ratio for the disinfection segment based on either of the following methods:

a. Determine one inactivation ratio (CTcalc/CT99.9) before or at the first customer during peak hourly flow.

b. Determine successive CTcalc/CT99.9 values, representing sequential inactivation ratios, between the point of disinfectant application and a point before or at the first customer during peak hourly flow. The owner shall calculate the total inactivation ratio by determining (CTcalc/CT99.9) for each sequence and then adding the (CTcalc/CT99.9) values together to determine total inactivation (∑ (CTcalc/CT99.9)).

2. The owner using more than one point of disinfectant application before the first customer shall determine the CT value of each disinfection segment immediately before the next point of disinfectant application, or for the final segment before or at the first customer, during peak hourly flow. The (CTcalc/CT99.9) value of each segment and (∑ (CTcalc/CT99.9)) shall be calculated using the method in subdivision E 1 a or E 1 b of this subsection.

3. The owner shall determine the total logs of inactivation of Giardia lamblia by multiplying the value calculated in subdivision E 1 a or E 1 b of this subsection by 3.0.

4. The owner shall determine the total logs of inactivation of viruses by multiplying the value calculated in subdivision E 1 a or E 1 b of this subsection by 4.0.

F. A disinfection benchmark shall be calculated following the procedures in subdivisions F 1, F 2, and F 3 of this subsection.

1. For each year of profiling data collected and calculated, an owner shall determine the lowest mean monthly level of both Giardia lamblia and virus inactivation. The owner shall determine the mean Giardia lamblia and virus inactivation for each calendar month for each year of profiling data by dividing the sum of daily or weekly Giardia lamblia and virus log inactivation by the number of values calculated for that month.

2. The disinfection benchmark is the lowest monthly mean value (for waterworks with one year of profiling data) or the mean of the lowest monthly mean values (for waterworks with more than one year of profiling data) of Giardia lamblia and virus log inactivation in each year of profiling data.

3. The owner of a waterworks using chloramines, ozone, or chlorine dioxide for primary disinfection shall calculate the disinfection benchmark for viruses from the data collected in the same manner used to calculate the Giardia lamblia disinfection benchmark.

G. The owner shall retain the disinfection profile in graphic form, as a spreadsheet or in some other format acceptable to the department for evaluation as part of sanitary surveys conducted by the department.

H. Before making a significant change to the waterworks disinfection practice, the owner shall review the disinfection benchmark and consult with the department.

1. Significant changes to disinfection practice are (i) changes to the point of disinfectant application, (ii) changes to the disinfectants used in the treatment plant, (iii) changes to the disinfection process, and (iv) any other modification identified by the department.

2. The owner shall submit the following information to the department as part of the consultation process: (i) a description of the proposed change; (ii) the disinfection profile and benchmarks established for Giardia lamblia and, if necessary, viruses; (iii) an analysis of how the proposed change will affect the current levels of disinfection; and (iv) any additional information to justify the change.

TABLE 500.2
CT Values for 3-Log Inactivation of Giardia lamblia by Free Chlorine at Less than 0.5oC

FREE RESIDUAL
(mg/L)

pH

≤ 6.06.5

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

TABLE 500.3
CT Values for 3-Log Inactivation of Giardia lamblia by Free Chlorine at 5oC

FREE RESIDUAL

(mg/L)

pH

≤ 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 500.4
CT Values for 3-Log Inactivation of Giardia lamblia by Free Chlorine at 10oC

FREE RESIDUAL

(mg/L)

pH

≤ 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 500.5
CT Values for 3-Log Inactivation of Giardia lamblia by Free Chlorine at 15oC

FREE RESIDUAL

(mg/L)

pH

≤ 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 500.6
CT Values for 3-Log Inactivation of Giardia lamblia by Free Chlorine at 20oC

FREE RESIDUAL

(mg/L)

pH

≤ 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 500.7
CT Values for 3-Log Inactivation of Giardia lamblia by Free Chlorine at 25oC and Higher

FREE RESIDUAL

(mg/L)

pH

≤ 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 500.8
CT Values for Inactivation of Viruses by Free Chlorine, pH 6.0-9.0

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

0.5

1

2

3

4

5

6

7

8

2

6.0

5.8

5.3

4.9

4.4

4.0

3.8

3.6

3.4

3

9.0

8.7

8.0

7.3

6.7

6.0

5.6

5.2

4.8

4

12.0

11.6

10.7

9.8

8.9

8.0

7.6

7.2

6.8

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

9

10

11

12

13

14

15

16

17

2

3.2

3.0

2.8

2.6

2.4

2.2

2.0

1.8

1.6

3

4.4

4.0

3.8

3.6

3.4

3.2

3.0

2.8

2.6

4

6.4

6.0

5.6

5.2

4.8

4.4

4.0

3.8

3.6

LOG INACTIVATION 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

TABLE 500.9
CT Values for Inactivation of Giardia lamblia by Chlorine Dioxide, pH 6.0-9.0

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

1

2

3

4

5

6

7

8

9

0.5

10.0

8.6

7.2

5.7

4.3

4.2

4.2

4.1

4.1

1

21.0

17.9

14.9

11.8

8.7

8.5

8.3

8.1

7.9

1.5

32.0

27.3

22.5

17.8

13.0

12.8

12.6

12.4

12.2

2

42.0

35.8

29.5

23.3

17.0

16.6

16.2

15.8

15.4

2.5

52.0

44.5

37.0

29.5

22.0

21.4

20.8

20.2

19.6

3

63.0

53.8

44.5

35.3

26.0

25.4

24.8

24.2

23.6

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

10

11

12

13

14

15

16

17

18

0.5

4.0

3.8

3.7

3.5

3.4

3.2

3.1

2.9

2.8

1

7.7

7.4

7.1

6.9

6.6

6.3

6.0

5.8

5.5

1.5

12.0

11.6

11.2

10.8

10.4

10.0

9.5

9.0

8.5

2

15.0

14.6

14.2

13.8

13.4

13.0

12.4

11.8

11.2

2.5

19.0

3.8

3.7

3.5

3.4

3.2

3.1

2.9

2.8

3

23.0

7.4

7.1

6.9

6.6

6.3

6.0

5.8

5.5

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

19

20

21

22

23

24

25

0.5

2.6

2.5

2.4

2.3

2.2

2.1

2.0

1

5.3

5.0

4.7

4.5

4.2

4.0

3.7

1.5

8.0

7.5

7.1

6.7

6.3

5.9

5.5

2

10.6

10.0

9.5

8.9

8.4

7.8

7.3

2.5

2.6

2.5

12.2

11.4

10.6

9.8

9.0

3

5.3

5.0

14.2

13.4

12.6

11.8

11.0

TABLE 500.10
CT Values for Inactivation of Virus by Chlorine Dioxide, pH 6.0-9.0

LOG INACTIVATION 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

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

10

11

12

13

14

15

16

17

18

2

4.2

3.9

3.6

3.4

3.1

2.8

2.7

2.5

2.4

3

12.8

12.0

11.1

10.3

9.4

8.6

8.2

7.7

7.3

4

25.1

23.4

21.7

20.1

18.4

16.7

15.9

15.0

14.2

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

19

20

21

22

23

24

25

2

2.2

2.1

2.0

1.8

1.7

1.5

1.4

3

6.8

6.4

6.0

5.6

5.1

4.7

4.3

4

13.3

12.5

11.7

10.9

10.0

9.2

8.4

TABLE 500.11
CT Values for Inactivation of Giardia lamblia by Chloramines, pH 6.0-9.0

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

1

2

3

4

5

6

7

8

9

0.5

635

568

500

433

365

354

343

332

321

1

1,270

1,136

1,003

869

735

711

687

663

639

1.5

1,900

1,700

1,500

1,300

1,100

1,066

1,032

998

964

2

2,535

2,269

2,003

1,736

1,470

1,422

1,374

1,326

1,278

2.5

3,170

2,835

2,500

2,165

1,830

1,772

1,714

1,656

1,598

3

3,800

3,400

3,000

2,600

2,200

2,130

2,060

1,990

1,920

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

10

11

12

13

14

15

16

17

18

0.5

310

298

286

274

262

250

237

224

211

1

615

592

569

546

523

500

474

448

422

1.5

930

894

858

822

786

750

710

670

630

2

1,230

1,184

1,138

1,092

1,046

1,000

947

894

841

2.5

1,540

1,482

1,424

1,366

1,308

1,250

1,183

1,116

1,049

3

1,850

1,780

1,710

1,640

1,570

1,500

1,420

1,340

1,260

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

19

20

21

22

23

24

25

0.5

198

185

173

161

149

137

125

1

396

370

346

322

298

274

250

1.5

590

550

515

480

445

410

375

2

788

735

688

641

594

547

500

2.5

982

915

857

799

741

683

625

3

1,180

1,100

1,030

960

890

820

750

TABLE 500.12
CT Values for Inactivation of Virus by Chloramines, pH 6.0-9.0

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

1

2

3

4

5

6

7

8

9

2

1,243

1,147

1,050

954

857

814

771

729

686

3

2,063

1,903

1,743

1,583

1,423

1,352

1,281

1,209

1,138

4

2,883

2,659

2,436

2,212

1,988

1,889

1,789

1,690

1,590

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

10

11

12

13

14

15

16

17

18

2

643

600

557

514

471

428

407

385

364

3

1,067

996

925

854

783

712

676

641

605

4

1,491

1392

1292

1193

1,093

994

944

895

845

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

19

20

21

22

23

24

25

2

342

321

300

278

257

235

214

3

570

534

498

463

427

392

356

4

796

746

696

646

597

547

497

TABLE 500.13
CT Values for Inactivation of Giardia lamblia by Ozone

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

1

2

3

4

5

6

7

8

9

0.5

0.48

0.44

0.40

0.36

0.32

0.30

0.28

0.27

0.25

1

0.97

0.89

0.80

0.72

0.63

0.60

0.57

0.54

0.51

1.5

1.50

1.36

1.23

1.09

0.95

0.90

0.86

0.81

0.77

2

1.90

1.75

1.60

1.45

1.30

1.23

1.16

1.09

1.02

2.5

2.40

2.20

2.00

1.80

1.60

1.52

1.44

1.36

1.28

3

2.90

2.65

2.40

2.15

1.90

1.81

1.71

1.62

1.52

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

10

11

12

13

14

15

16

17

18

0.5

0.23

0.22

0.20

0.19

0.17

0.16

0.15

0.14

0.14

1

0.48

0.45

0.42

0.38

0.35

0.32

0.30

0.29

0.27

1.5

0.72

0.67

0.62

0.58

0.53

0.48

0.46

0.43

0.41

2

0.95

0.89

0.82

0.76

0.69

0.63

0.60

0.57

0.54

2.5

1.20

1.12

1.04

0.95

0.87

0.79

0.75

0.71

0.68

3

1.43

1.33

1.24

1.14

1.05

0.95

0.90

0.86

0.81

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

19

20

21

22

23

24

25

0.5

0.13

0.12

0.11

0.10

0.10

0.09

0.08

1

0.26

0.24

0.22

0.21

0.19

0.18

0.16

1.5

0.38

0.36

0.34

0.31

0.29

0.26

0.24

2

0.51

0.48

0.45

0.42

0.38

0.35

0.32

2.5

0.64

0.60

0.56

0.52

0.48

0.44

0.40

3

0.13

0.12

0.11

0.10

0.10

0.09

0.08

TABLE 500.14
CT Values for Inactivation of Virus by Ozone

LOG INACTIVATION 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

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

10

11

12

13

14

15

16

17

18

2

0.50

0.46

0.42

0.38

0.34

0.30

0.29

0.28

0.27

3

0.80

0.74

0.68

0.62

0.56

0.50

0.48

0.46

0.44

4

1.00

0.92

0.84

0.76

0.68

0.60

0.58

0.56

0.54

LOG INACTIVATION CREDIT

WATER TEMPERATURE (°C)

19

20

21

22

23

24

25

2

0.26

0.25

0.23

0.21

0.19

0.17

0.15

3

0.42

0.40

0.37

0.34

0.31

0.28

0.25

4

0.52

0.50

0.46

0.42

0.38

0.34

0.30

TABLE 500.15
Baffling Classifications

BAFFLING CONDITION

T10/T

BAFFLING DESCRIPTION

Unbaffled (mixed flow)

0.1

None, agitated basin, very low length-to-width ratio, high inlet and outlet flow velocities

Poor

0.3

Single or multiple unbaffled inlets and outlets, no intra-basin baffles

Average

0.5

Baffled inlet or outlet with some intra-basin baffles

Superior

0.7

Perforated inlet baffle, serpentine or perforated intra-basin baffles, outlet weir or perforated launders

Statutory Authority

§§ 32.1-12 and 32.1-170 of the Code of Virginia.

Historical Notes

Derived from VR355-18-005.06 § 2.17, eff. August 1, 1991; amended, Virginia Register Volume 9, Issue 17, eff. June 23, 1993; Volume 18, Issue 19, eff. July 3, 2002; Volume 21, Issue 13, eff. April 6, 2005; Volume 25, Issue 5, eff. December 10, 2008; Volume 28, Issue 5, eff. December 7, 2011; Volume 37, Issue 20, eff. June 23, 2021.

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