Current through Register Vol. 39, No. 6, September 16, 2024
The Department shall publish on the Department website and
annually revise maximum soil contaminant concentrations to be used as soil
cleanup levels for contamination from petroleum underground storage tank
systems. The Department shall establish maximum soil contaminant concentrations
for residential, industrial/commercial, and soil-to-groundwater exposures as
follows:
(1) The following equations
and references shall be used in establishing residential maximum soil
contaminant concentrations. Equation 1 shall be used for each contaminant with
an EPA carcinogenic classification of A, B1, B2, C, D or E. Equation 2 shall be
used for each contaminant with an EPA carcinogenic classification of A, B1, B2
or C. The maximum soil contaminant concentration shall be the lower of the
concentrations derived from Equations 1 and 2.
(a) Equation 1: Non-cancer Risk-based
Residential Ingestion Concentration
Soil mg/kg =[0.2 x oral chronic reference dose x body
weight, age 1 to 6 x averaging time noncarcinogens] / [exposure frequency x
exposure duration, age 1 to 6 x (soil ingestion rate, age 1 to 6 /
106 mg/kg)].
(b) Equation 2: Cancer Risk-based Residential
Ingestion Concentration
Soil mg/kg =[target cancer risk of
10-6 x averaging time carcinogens] / [exposure
frequency x (soil ingestion factor, age adjusted /
106mg/kg) x oral cancer slope factor]. The age
adjusted soil ingestion factor shall be calculated by: [(exposure duration, age
1 to 6 x soil ingestion rate, age 1 to 6) /( body weight, age 1 to 6)] +
[((exposure duration, total - exposure duration, age 1 to 6) x soil ingestion,
adult) / (body weight, adult)].
(c) The exposure factors selected in
calculating the residential maximum soil contaminant concentrations shall be
within the recommended ranges specified in the following references or the most
recent version of these references:
(i) EPA,
2011. Exposure Factors Handbook, incorporated by reference including subsequent
amendments or editions and may be obtained electronically free of charge from
the United States Environmental Protection Agency website at
https://cfpub.epa.gov/ncea/risk/recordisplay.cfm?deid=236252;
(ii) EPA, 1991. Risk Assessment Guidance for
Superfund: Volume I Human Health Evaluation Manual (Part B, Development of Risk
Based Preliminary Remediation Goals), incorporated by reference including
subsequent amendments or editions and may be obtained electronically free of
charge from the United States Environmental Protection Agency website at
https://www.epa.gov/risk/risk-assessment-guidance-superfund-rags-part-b;
(iii) EPA. Regional Screening Level Generic
Tables (RSL) and User's Guide, incorporated by reference including subsequent
amendments or editions and may be obtained electronically free of charge from
the United States Environmental Protection Agency website at
https://www.epa.gov/risk/regional-screening-levels-rsls;
and
(iv) EPA, 2018. Region 4 Human
Health Risk Assessment Supplemental Guidance, incorporated by reference
including subsequent amendments or editions and may be obtained electronically
free of charge from the United States Environmental Protection Agency website
at
https://www.epa.gov/sites/production/files/2018-03/documents/hhra_regional_supplemental_guidance_report-march-2018_update.pdf.
(d) The following references or
the most recent version of these references, in order of preference, shall be
used to obtain oral chronic reference doses and oral cancer slope factors:
(i) EPA. Integrated Risk Information System
(IRIS) Computer Database, incorporated by reference including subsequent
amendments or editions and may be obtained electronically free of charge from
the United States Environmental Protection Agency website at
https://www.epa.gov/iris;
(ii) EPA. Health Effects Assessment Summary
Tables (HEAST), incorporated by reference including subsequent amendments or
editions and may be obtained electronically free of charge from the United
States Environmental Protection Agency website at
https://epa-heast.ornl.gov;
(iii) EPA. Regional Screening Level Generic
Tables (RSL) and User's Guide;
(iv)
EPA, 2018. Region 4 Human Health Risk Assessment Supplemental Guidance;
and
(v) Other scientifically valid
peer-reviewed published health risk assessment data, and scientifically valid
peer-reviewed published toxicological data.
(2) The following equations and references
shall be used in establishing industrial/commercial maximum soil contaminant
concentrations. Equation 1 shall be used for each contaminant with an EPA
carcinogenic classification of A, B1, B2, C, D or E. Equation 2 shall be used
for each contaminant with an EPA carcinogenic classification of A, B1, B2 or C.
The maximum soil contaminant concentration shall be the lower of the
concentrations derived from Equations 1 and 2.
(a) Equation 1: Non-cancer Risk-based
Industrial/Commercial Ingestion Concentration
Soil mg/kg =[0.2 x oral chronic reference dose x body
weight, adult x averaging time noncarcinogens] / [exposure frequency x exposure
duration, adult x (soil ingestion rate, adult / 106
mg/kg) x fraction of contaminated soil ingested].
(b) Equation 2: Cancer Risk-based
Industrial/Commercial Ingestion Concentration
Soil mg/kg =[target cancer risk of
10-6 x body weight, adult x averaging time
carcinogens] / [exposure frequency x exposure duration, adult x (soil ingestion
rate, adult / 106 mg/kg) x fraction of contaminated
soil ingested x oral cancer slope factor].
(c) The exposure factors selected in
calculating the industrial/commercial maximum soil contaminant concentrations
shall be within the recommended ranges specified in the following references or
the most recent version of these references:
(i) EPA, 2011. Exposure Factors
Handbook;
(ii) EPA, 1991. Risk
Assessment Guidance for Superfund: Volume I Human Health Evaluation Manual
(Part B, Development of Risk Based Preliminary Remediation Goals);
(iii) EPA. Regional Screening Level Generic
Tables (RSL) and User's Guide; and
(iv) EPA, 2018. Region 4 Human Health Risk
Assessment Supplemental Guidance.
(d) The following references or the most
recent version of these references, in order of preference, shall be used to
obtain oral chronic reference doses and oral cancer slope factors:
(i) EPA. Integrated Risk Information System
(IRIS) Computer Database;
(ii) EPA.
Health Effects Assessment Summary Tables (HEAST);
(iii) EPA. Regional Screening Level Generic
Tables (RSL) and User's Guide;
(iv)
EPA, 2018. Region 4 Human Health Risk Assessment Supplemental Guidance;
and
(v) Other scientifically valid
peer-reviewed published health risk assessment data, and scientifically valid
peer-reviewed published toxicological data.
(3) The following equations and references
shall be used in establishing the soil-to-groundwater maximum contaminant
concentrations:
(a) Organic Constituents:
Soil mg/kg = groundwater standard or interim standard x
[(.02 x soil organic carbon-water partition coefficient) + 4 + (1.733 x 41 x
Henry's Law Constant (atm.-m3/mole))].
(i) If no groundwater standard or interim
standard has been established under Rule .0202 of this Subchapter, the
practical quantitation limit shall be used in lieu of a standard to calculate
the soil-to-groundwater maximum contaminant concentrations.
(ii) The following references or the most
recent version of these references, in order of preference, shall be used to
obtain soil organic carbon-water partition coefficients and Henry's Law
Constants:
(A) EPA. Superfund Chemical Data
Matrix (SCDM),incorporated by reference including subsequent amendments or
editions and may be obtained electronically free of charge from the United
States Environmental Protection Agency website at
https://www.epa.gov/superfund/superfund-chemical-data-matrix-scdm;
(B) EPA, 1991. Risk Assessment Guidance for
Superfund: Volume I Human Health Evaluation Manual (Part A), incorporated by
reference including subsequent amendments or editions and may be obtained
electronically free of charge from the United States Environmental Protection
Agency website at
https://www.epa.gov/risk/risk-assessment-guidance-superfund-rags-part/;
it is Volume I of the three-volume set called Risk Assessment Guidance for
Superfund;
(C) Agency for Toxic
Substances and Disease Registry, "Toxicological Profile for [individual
chemical]," incorporated by reference including subsequent amendments or
editions and may be obtained electronically free of charge from the United
States Agency for Toxic substances and Disease Registry website at
https://www.atsdr.cdc.gov/substances/index.asp;
(D) Montgomery, J.H., 2007. Groundwater
Chemicals Desk Reference. CRC Press. This document is incorporated by reference
including subsequent amendments and editions, and may be obtained for a charge
of two hundred ninety six dollars ($296.00) at
https://www.crcpress.com/Groundwater-Chemicals-Desk-Reference/Montgomery/p/book/9780849392764/
or a copy may be reviewed at the Division of Waste Management, Underground
Storage Tank Section office at 217 West Jones Street, Raleigh, N.C. 27603;
and
(E) Other scientifically valid
peer-reviewed published data.
(b) Inorganic Constituents:
Soil mg/kg = groundwater standard or interim standard x
[(20 x soil-water partition coefficient for pH of 5.5) + 4 + (1.733 x 41 x
Henry's Law Constant (atm.-m3/mole))].
(i) If no groundwater standard or interim
standard has been established under Rule .0202 of this Subchapter, the
practical quantitation limit shall be used in lieu of a standard to calculate
the soil-to-groundwater maximum contaminant concentrations.
(ii) The following references or the most
recent version of these references, in order of preference, shall be used to
obtain soil-water partition coefficients and Henry's Law Constants:
(A) EPA. Superfund Chemical Data Matrix
(SCDM);
(B) Baes, C.F., III, R.D.
Sharp, A.L. Sjoreen, and R.W. Shor, 1984. A Review and Analysis of Parameters
for Assessing Transport of Environmentally Released Radionuclides Through
Agriculture. Oak Ridge National Laboratory, incorporated by reference including
subsequent amendments or editions and may be obtained electronically free of
charge from the United States Nuclear Regulatory Commission website at
https://www.nrc.gov;
(C) Agency for Toxic Substances and Disease
Registry, "Toxicological Profile for [individual chemical];" and
(D) Other scientifically valid peer-reviewed
published data.
Authority
G.S.
143-215.2;
143-215.3(a)(1);
143-215.94A;
143-215.94E;
143-215.94T;
143-215.94V;
143B-282; 1995 (Reg. Sess. 1996)
c. 648,s. 1;
Recodified from
15A NCAC
02L .0115(m);
Amended Eff. December 1, 2005;
Readopted Eff. June 1,
2019.
