15A NCAC 02L .0202 GROUNDWATER QUALITY STANDARDS
(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.
(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.
(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.
History Note: 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.