North Carolina Administrative Code
Title 15A - Environmental Quality
Chapter 02 - ENVIRONMENTAL MANAGEMENT
Subchapter L - GROUNDWATER CLASSIFICATION AND STANDARDS
Section .0200 - CLASSIFICATIONS AND GROUNDWATER QUALITY STANDARDS
Section 02L .0202 - GROUNDWATER QUALITY STANDARDS

Universal Citation: 15A NC Admin Code 02L .0202

Current through Register Vol. 39, No. 6, September 16, 2024

(a) The groundwater quality standards for the protection of the groundwaters of the State are those specified in this Rule. They are the maximum allowable concentrations resulting from any discharge of contaminants to the land or waters of the State, which may be tolerated without creating a threat to human health or which would otherwise render the groundwater unsuitable for its intended best usage.

(b) The groundwater quality standards for contaminants specified in Paragraphs (h) and (i) of this Rule are as listed, except that:

(1) Where the standard for a substance is less than the practical quantitation limit, the detection of that substance at or above the practical quantitation limit constitutes a violation of the standard. The practical quantitation limit, defined in Rule .0102 of this Subchapter, is a scientific standard pursuant to G.S. 150B-2(8a)(h).

(2) Where two or more substances exist in combination, the Director shall consider the effects of chemical interactions after consulting with the Division of Public Health and may establish maximum concentrations at values less than those established in accordance with Paragraphs (c), (h), or (i) of this Rule, based on additive toxic effects. In the absence of information to the contrary, in accordance with Paragraph (d) of this Rule, the carcinogenic risks associated with carcinogens present shall be considered additive and the toxic effects associated with non-carcinogens present shall also be considered additive.

(3) Where naturally occurring substances exceed the established standard, the standard shall be the naturally occurring concentration as established by the Director based upon site-specific conditions.

(4) Where the groundwater standard for a substance is greater than the Maximum Contaminant Level (MCL), the Director shall apply the MCL as the groundwater standard at any private drinking water well or public water system well that may be impacted.

(c) Except for tracers, the use of which has been permitted by the Division in 15A NCAC 02C .0200, substances that are not naturally occurring and for which no standard is specified in Paragraphs (h) or (i) of this Rule shall not be permitted in concentrations at or above the practical quantitation limit in Class GA or Class GSA groundwaters. Any person may request the Director of the Division of Water Resources modify this requirement by establishing an Interim Maximum Allowable Concentration (IMAC) in accordance with the specific guidelines listed in Subparagraphs (1)-(9) of this Paragraph. In addition, any person may request the Director of the Division of Water Resources to update or remove an existing IMAC in accordance with the specific guidelines listed in Subparagraphs (1)-(9) of this Paragraph. The requestor shall submit relevant toxicological and epidemiological data, study results, and calculations in accordance with Paragraphs (d) and (e) of this Rule. The specific guidelines are as follows:

(1) The Division shall review the request to determine whether the information submitted is in accordance with Paragraphs (d) and (e) of this Rule.

(2) If the information submitted is not in accordance with Paragraphs (d) and (e) of this Rule, the Director of the Division of Water Resources shall request additional information from the requester. If the requester does not provide the additional information necessary to be in accordance with Paragraphs (d) and (e) of this Rule, the Director of the Division of Water Resources shall return the request.

(3) If the information submitted is in accordance with Paragraphs (d) and (e) of this Rule, at least 30 days prior to establishing, updating, or removing an IMAC for any substance, the Division of Water Resources shall provide public notice and opportunity for comment that an IMAC has been requested to be established, updated, or removed. The public notice shall include:
(A) the request for the establishment, update, or removal of the IMAC for a substance,

(B) the level of the proposed IMAC, which is calculated by the Division of Water Resources in accordance with Paragraphs (d) and (e) of this Rule,

(C) if applicable the level of the existing IMAC, and

(D) the basis upon which the Division of Water Resources has relied in development of the proposed IMAC establishment, update, or removal.

This notice shall be emailed to interested parties and posted on the Division of Water Resources' website: https://deq.nc.gov/about/divisions/water-resources/water-planning/classification-standards/groundwater-imacs.

(4) If the Director of the Division of Water Resources finds the establishment, update or removal will not degrade the quality of the groundwaters, will not likely cause or contribute to pollution of the waters of the state, and will be protective of public health, then the Director shall establish, update or remove the IMAC. If the request does not meet the requirements listed in this Subparagraph, the Director of the Division of Water Resources shall return the request. The Director shall establish, update, or remove the IMAC or return the request within 180 calendar days of receipt of a request submitted in accordance with Paragraphs (d) and (e) of this Rule unless the requester agrees, in writing, to a longer period. Failure by the Director to establish, update or remove an IMAC or return the request within 180 days of receipt of a request submitted in accordance with Paragraphs (d) and (e) of this Rule shall be considered a return of the request.

(5) If the Director of the Division of Water Resources establishes or updates an IMAC, the IMAC shall be posted on the Division of Water Resource's website and the Commission shall be notified in writing within 30 calendar days and at the next regularly scheduled Commission meeting that a new IMAC has been established or an existing IMAC has been updated or removed.

(6)
(A) Within 12 months of establishing an IMAC pursuant to this Paragraph, the Director of the Division of Water Resources shall make a recommendation to the Commission whether:
(i) a new groundwater standard in place of the IMAC should be established pursuant to this Rule; or

(ii) the IMAC should expire.

(B) After a recommendation is presented by the Director under Part (A) of this Subparagraph, the Commission shall decide whether rulemaking shall be initiated to adopt a new groundwater standard in place of the IMAC.

(C) If the Commission initiates rulemaking to adopt a new groundwater standard in place of the IMAC, then the IMAC shall remain in effect unless it expires under Subparagraph (7) of this Paragraph.

(7) An IMAC shall expire upon the earliest of:
(A) the date the Commission declines to initiate rulemaking to adopt a new groundwater standard in place of the IMAC under Part (B) of Subparagraph (c)(6);

(B) the effective date of a Rule adopted by the Commission establishing a new groundwater standard in place of the IMAC; or

(C) after initiating rulemaking pursuant to Part (C) of Subparagraph (c)(6), the date the Commission declines to adopt a new groundwater standard in place of the IMAC.

(8) For any IMAC that expires prior to the adoption by the Commission of a new groundwater standard in place of the IMAC, any person may request an IMAC be established again under this Paragraph based on new information in accordance with Paragraphs (d) and (e) of this Rule that was not included in the original IMAC request to the Director or new site information that was not included in the original IMAC request to the Director.

(9) The Director of the Division of Water Resources shall provide an annual update to the Commission on the status of pending IMAC requests and any IMACs that have been established, updated or removed during the previous calendar year.

(d) Except as provided in Paragraph (f) of this Rule, groundwater quality standards for substances in Class GA and Class GSA groundwaters are established as the least of:

(1) Systemic threshold concentration calculated as follows: [Reference Dose (mg/kg/day) x 70 kg (adult body weight) x Relative Source Contribution (0.10 for inorganics; 0.20 for organics)] / [2 liters/day (avg. water consumption)];

(2) Concentration that corresponds to an incremental lifetime cancer risk of 1x10-6;

(3) Taste threshold limit value;

(4) Odor threshold limit value;

(5) Maximum contaminant level; or

(6) National secondary drinking water standard.

(e) The following references, in order of preference, shall be used in establishing concentrations of substances which correspond to levels described in Paragraph (d) of this Rule:

(1) Integrated Risk Information System (U.S. EPA);

(2) Health Advisories (U.S. EPA Office of Drinking Water);

(3) Other health risk assessment data published by the U.S. EPA; or

(4) Other relevant, published health risk assessment data, and scientifically valid peer-reviewed published toxicological data.

(f) The Commission may establish groundwater standards less stringent than existing maximum contaminant levels or national secondary drinking water standards if it finds, after public notice and opportunity for hearing in accordance with G.S. 150B, that:

(1) more recent data published in the EPA health references listed in Paragraph (e) of this Rule results in a standard that is protective of public health, taste threshold, or odor threshold;

(2) the standard will not endanger the public health and safety, including health and environmental effects from exposure to groundwater contaminants; and

(3) compliance with a standard based on the maximum contaminant level or national secondary drinking water standard would produce substantial hardship without equal or greater public benefit.

(g) Groundwater quality standards specified in Paragraphs (h) and (i) of this Rule shall be reviewed by the Division of Water Resources on a triennial basis to consider whether to recommend to the Commission that new or revised groundwater quality standards be adopted in accordance with Paragraphs (d) and (e) of this Rule.

(h) Class GA Standards. Unless otherwise indicated, the standard refers to the total concentration in micrograms per liter (µg/L) of any constituent in a dissolved, colloidal, or particulate form that is mobile in groundwater. These standards do not apply to sediment or other particulate matter that is preserved in a groundwater sample as a result of well construction or sampling procedures. The Class GA standards are:

Substance

Chemical Abstracts Service (CAS) Registry Number

Standard (µg/L)

Acenaphthene

83-32-9

80

Acenaphthylene

208-96-8

200

Acetic acid

64-19-7

5,000

Acetochlor

34256-82-1

100

Acetochlor ESA

187022-11-3

500

Acetochlor OXA

184992-44-4

500

Acetone

67-64-1

6,000

Acetophenone

98-86-2

700

Acrolein

107-02-8

4

Acrylamide

79-06-1

0.008

Alachlor

15972-60-8

2

Aldrin

309-00-2

0.002

Anthracene

120-12-7

2,000

Antimony

7440-36-0

1

Arsenic

7440-38-2

10

Atrazine and chlorotriazine metabolites

1912-24-9

3

Barium

7440-39-3

700

Benzene

71-43-2

1

Benzo(a)anthracene

56-55-3

0.05

Benzo(a)pyrene

50-32-8

0.005

Benzo(b)fluoranthene

205-99-2

0.05

Benzo(g,h,i)perylene

191-24-2

200

Benzo(k)fluoranthene

207-08-9

0.5

Benzoic acid

65-85-0

30,000

Benzyl alcohol

100-51-6

700

Beryllium

7440-41-7

4

Bis(chloroethyl)ether

111-44-4

0.03

Bis(2-ethylhexyl) phthalate

117-81-7

3

Boron

7440-42-8

700

Bromodichloromethane

75-27-4

0.6

Bromoform

75-25-2

4

Bromomethane

74-83-9

10

n-Butanol

71-36-3

590

sec-Butanol

78-92-2

10,000

n-Butylbenzene

104-51-8

70

sec-Butylbenzene

135-98-8

70

tert-Butylbenzene

98-06-6

70

Butylbenzyl phthalate

85-68-7

1,000

Cadmium

7440-43-9

2

Caprolactam

105-60-2

4,000

Carbofuran

1563-66-2

40

Carbon disulfide

75-15-0

700

Carbon tetrachloride

56-23-5

0.3

Chlordane

12789-03-6

0.1

Chloride

16887-00-6

250,000

Chlorobenzene

108-90-7

50

Chloroethane

75-00-3

3,000

Chloroform

67-66-3

70

Chloromethane

74-87-3

3

2-Chlorophenol

95-57-8

0.4

2-Chlorotoluene

95-49-8

100

4-Chlorotoluene

106-43-4

24

Chromium

7440-47-3

10

Chrysene

218-01-9

5

Cobalt

7440-48-4

1

Coliform organisms (total)

No CAS Registry Number

1 per 100 mL

Color

No CAS Registry Number

15 color units

Copper

7440-50-8

1,000

Cyanide (free cyanide)

57-12-5

70

2,4-D (2,4-dichlorophenoxy acetic acid)

94-75-7

70

Dalapon

75-99-0

200

DDD

72-54-8

0.1

DDE

72-55-9

0.1

DDT

50-29-3

0.1

Dibenz(a,h)anthracene

53-70-3

0.005

1,4-Dibromobenzene

106-37-6

70

Dibromochloromethane

124-48-1

0.4

1,2-Dibromo-3-chloropropane

96-12-8

0.04

Dibutyl phthalate

84-74-2

700

Dichloroacetic acid

79-43-6

0.7

1,2-Dichlorobenzene

95-50-1

20

1,3-Dichlorobenzene

541-73-1

200

1,4-Dichlorobenzene

106-46-7

6

Dichlorodifluoromethane

75-71-8

1,000

1,1-Dichloroethane

75-34-3

6

1,2-Dichloroethane

107-06-2

0.4

1,2-Dichloroethene (cis)

156-59-2

70

1,2-Dichloroethene (trans)

156-60-5

100

1,1-Dichloroethylene

75-35-4

350

2,4-Dichlorophenol

120-83-2

0.98

1,2-Dichloropropane

78-87-5

0.6

1,3-Dichloropropene (cis and trans isomers)

542-75-6

0.4

Dieldrin

60-57-1

0.002

Diethylphthalate

84-66-2

6,000

2,4-Dimethylphenol

105-67-9

100

2,4-Dinitrotoluene

121-14-2

0.05

2,6-Dinitrotoluene

606-20-2

0.05

Di-n-octyl phthalate

117-84-0

100

Dinoseb

88-85-7

7

1,4-Dioxane

123-91-1

3

Dioxin (2,3,7,8-TCDD)

1746-01-6

0.0002 ng/L

1,1-Diphenyl

92-52-4

400

Diphenyl ether

101-84-8

180

Diquat

85-00-7

20

Dissolved solids (total)

No CAS Registry Number

500,000

Disulfoton

298-04-4

0.3

Diundecyl phthalate (Santicizer 711)

3648-20-2

100

Endosulfan

115-29-7

40

Endosulfan sulfate

1031-07-8

40

Endothall

145-73-3

100

Endrin, total (includes endrin, endrin aldehyde, and endrin ketone)

72-20-8

2

Epichlorohydrin

106-89-8

4

Ethyl acetate

141-78-6

3,000

Ethylbenzene

100-41-4

600

Ethylene dibromide

106-93-4

0.02

Ethylene glycol

107-21-1

10,000

Fluoranthene

206-44-0

300

Fluorene

86-73-7

300

Fluoride

16984-48-8

2,000

Foaming agents

No CAS Registry Number

500

Formaldehyde

50-00-0

600

Gross alpha (adjusted) particle activity (excludes radium-226 and uranium)

12587-46-1

15 pCi/L

Heptachlor

76-44-8

0.008

Heptachlor epoxide

1024-57-3

0.004

Heptane

142-82-5

400

Hexachlorobenzene

118-74-1

0.02

Hexachlorobutadiene

87-68-3

0.4

Hexachlorocyclohexane isomers (technical grade)

608-73-1

0.02

alpha-Hexachlorocyclohexane

319-84-6

0.006

beta-Hexachlorocyclohexane

319-85-7

0.02

gamma-Hexachlorocyclohexane (Lindane)

58-89-9

0.03

n-Hexane

110-54-3

400

Indeno(1,2,3-cd)pyrene

193-39-5

0.05

Iron

7439-89-6

300

Isophorone

78-59-1

40

Isopropyl ether

108-20-3

70

Isopropylbenzene

98-82-8

70

4-Isopropyltoluene

99-87-6

25

Lead

7439-92-1

15

Manganese

7439-96-5

50

Mercury

7439-97-6

1

Methanol

67-56-1

4,000

Methoxychlor

72-43-5

40

Methylene chloride

75-09-2

5

Methyl butyl ketone

591-78-6

40

Methyl ethyl ketone

78-93-3

4,000

Methyl isobutyl ketone

108-10-1

100

Methyl methacrylate

80-62-6

25

1-Methylnapthalene

90-12-0

1

2-Methylnaphthalene

91-57-6

30

2-Methylphenol

95-48-7

400

3-Methylphenol

108-39-4

400

4-Methylphenol

106-44-5

40

Methyl tert-butyl ether (MTBE)

1634-04-4

20

Naphthalene

91-20-3

6

Nickel

7440-02-0

100

Nitrate (as N)

14797-55-8

10,000

Nitrite (as N)

14797-65-0

1,000

N-nitrosodimethylamine

62-75-9

0.0007

Oxamyl

23135-22-0

200

Pentachlorophenol

87-86-5

0.3

Petroleum aliphatic carbon fraction class (C5 - C8)

No CAS Registry Number

400

Petroleum aliphatic carbon fraction class (C9 - C18)

No CAS Registry Number

700

Petroleum aliphatic carbon fraction class (C19 - C36)

No CAS Registry Number

10,000

Petroleum aromatics carbon fraction class (C9 - C22)

No CAS Registry Number

200

pH

No CAS Registry Number

6.5 - 8.5 (no unit)

Phenanthrene

85-01-8

200

Phenol

108-95-2

30

Phorate

298-02-2

1

n-Propylbenzene

103-65-1

70

Propylene glycol

57-55-6

100,000

Pyrene

129-00-0

200

Selenium

7782-49-2

20

Silver

7440-22-4

20

Simazine

122-34-9

4

Strontium

7440-24-6

2,000

Styrene

100-42-5

70

Sulfate

14808-79-8

250,000

1,2,4,5-Tetrachlorobenzene

95-94-3

2

1,1,2,2-Tetrachloroethane

79-34-5

0.2

1,1,1,2-Tetrachloroethane

630-20-6

1

Tetrachloroethylene (PCE)

127-18-4

0.7

2,3,4,6-Tetrachlorophenol

58-90-2

200

Thallium

7440-28-0

2

Tin (inorganic forms)

7440-31-5

2,000

Toluene

108-88-3

600

Toxaphene

8001-35-2

0.03

2,4,5-TP (Silvex)

93-72-1

50

1,2,4-Trichlorobenzene

120-82-1

70

1,1,1-Trichloroethane

71-55-6

200

1,1,2-Trichloroethane

79-00-5

0.6

Trichloroethylene (TCE)

79-01-6

3

Trichlorofluoromethane

75-69-4

2,000

2,4,5-Trichlorophenol

95-95-4

63

2,4,6-Trichlorophenol

88-06-2

4

1,2,3-Trichloropropane

96-18-4

0.005

1,2,4-Trimethylbenzene

95-63-6

400

1,3,5-Trimethylbenzene

108-67-8

400

Vanadium

7440-62-2

7

1,1,2-Trichloro-1,2,2-trifluoroethane

76-13-1

200,000

Vinyl chloride

75-01-4

0.03

Xylenes

1330-20-7

500

Zinc

7440-66-6

1,000

(i) Class GSA Standards. The standards for this class are the same as those for Class GA except as follows:

(1) chloride: allowable increase not to exceed 100 percent of the natural quality concentration; and

(2) dissolved solids (total): 1,000,000 µg/L.

(j) Class GC Standards.

(1) The concentrations of substances that, at the time of classification, exceed the standards applicable to Class GA or GSA groundwaters shall not be caused to increase, nor shall the concentrations of other substances be caused to exceed the GA or GSA standards as a result of further disposal of contaminants to or beneath the surface of the land within the boundary of the area classified GC.

(2) The concentrations of substances that, at the time of classification, exceed the standards applicable to GA or GSA groundwaters shall not be caused to migrate as a result of activities within the boundary of the GC classification, so as to violate the groundwater or surface water quality standards in adjoining waters of a different class.

(3) Concentrations of specific substances, that exceed the established standard at the time of classification, are listed in Section .0300 of this Subchapter.

Authority G.S. 143-214.1; 143-214.2; 143-215.3(a)(1); 143-215.3(a)(4); 143B-282(a)(2); 150B-2(8a)(h); 150B-19(6);
Eff. June 10, 1979;
Amended Eff. November 1, 1994; October 1, 1993; September 1, 1992; August 1, 1989;
Temporary Amendment Eff. June 30, 2002;
Amended Eff. August 1, 2002;
Temporary Amendment Expired February 9, 2003;
Amended Eff. April 1, 2013; January 1, 2010; April 1, 2005;
Pursuant to G.S. 150B-21.3A, rule is necessary without substantive public interest Eff. March 6, 2018;
Amended Eff. April 1, 2022.

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