620 Groundwater Quality

Draft Proposed Rules

The Illinois EPA is proposing draft language to update 35 Ill. Adm. Code 620. The proposed updates include nine new chemicals, three new atrazine metabolites, and procedures for selecting toxicity values consistent with current federal guidance. Definitions are updated and references are consistent with those criteria and practices as incorporated. Site specific groundwater standards for designated Class III Special Resource Groundwater are also added. Exposure factors are updated, and the Human Non-Threshold Toxicant Advisory Concentration model is updated. Tables for similar-acting constituents are added.  Finally, this proposal includes groundwater quality standards for five Per- and Polyfluoroalkyl Substances (PFAS): perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorononanoic acid (PFNA), perfluorohexanesulfonic acid (PFHxS), and perfluorobutanesulfonic acid (PFBS).

Public Comment 

Prior to submitting proposed rules to the Illinois Pollution Control Board for review and final adoption, the Illinois EPA is soliciting public comment on draft proposed rules.  The Illinois EPA will accept written public comment until June 25, 2021. Comments should be submitted to EPA.620.rulemaking@illinois.gov. All comments, including proposed alternative language, received by Illinois EPA will be considered prior to the Agency filing the proposed rule with Illinois Pollution Control Board. Questions about the process or rulemaking should be submitted to the e-mail address above.

Public Meeting

The Illinois EPA will host a virtual public meeting to review the proposed changes and answer questions concerning the proposal. The meeting will be held at 1:00 pm on May 26, 2021. More information may be found in the Comment Period and Meeting Notice, below.

The meeting link is:

https://illinois.webex.com/illinois/j.php?MTID=m19e9dc943bb9f835453fc6b6e8823826

If you have questions about connecting to the meeting, contact Jeff Guy at (217) 785-8724 or by submitting an e-mail to EPA.620.rulemaking@illinois.gov

Documents

Draft Proposed 35 Ill. Adm. Code 620 *the attached document includes only the sections proposed for updates

A copy of the current 35 Ill. Adm. Code 620

Factsheet

Table - Part 620 Proposed Groundwater Quality Standards

Comment Period and Meeting Notice

Key Provisions

1. Updates the methodology located in Appendix A for developing oral reference doses (RfDs), when a verified RfD is not available. The updated methodology is the method used by Integrated Risk Information Systems (IRIS), the Tier 1 source for selecting toxicity criteria.

 

2. Formalizes the hierarchy currently used by Illinois EPA for selecting a verified RfD from various sources. The hierarchy is located in Appendix A.

 

3. Updates to Exposure Factors listed in the models as follows:

Non-Carcinogen Model (Human Threshold Toxicant Advisory Concentration – HTTAC)

            Updated exposure factors from an average adult to a child 0-6 years of age

SymbolParameterExisting ValueUpdated Value
BW (kg)Body Weight7015
W (L/day)Per Capita Daily Water Ingestion Rate20.78

 

Updated Value Sources

BW: Exposure Factors Handbook, 2011 (U.S. EPA), Table 8-1; weighted average of mean body weights (birth to less than 6 years of age). Utilized in the U.S. EPA Regional Screening Level (RSL) calculator for a child 0 – 6 years of age.

W:  Exposure Factors Handbook, 2011 (U.S. EPA), Tables 3-15 and 3-33; weighted average of 90th percentile consumer-only ingestion of drinking water (birth to less than 6 years of age). Utilized in the U.S. EPA Regional Screening Level (RSL) calculator for a child 0 – 6 years of age.

Carcinogen Model (Human Non-Threshold Toxicant Advisory Concentration – HNTAC)

Due to updates to the source of the HNTAC model, the model is updated as follows:

  • Current model

Current Model Exposure Factors

SymbolParameterExisting Value
BW (kg)Body Weight70
IR (L/day)Daily Water Ingestion Rate2
EF (days/year)Exposure Frequency350
ED (year)Exposure Duration30

 

  • Updated model

The age-adjusted drinking water ingestion rate (IFWadj) is an exposure value calculated using an age-adjusted intake factors equation and equals 327.95 L/kg:

Updated exposure factors for the IFWadj equation

SymbolParameterUpdated Value
EF all (days/year)Exposure Frequency350
EDchild (years)Exposure Duration – child6
IRWchild (L/day)Daily Water Ingestion Rate – child0.78
BWchild (kg)Body Weight – child15
EDadult (year)Exposure Duration – adult20
IRWadult (L/day)Daily Water Ingestion Rate – adult2.5
BWadult (kg)Body Weight – adult80

 

Updated Value Sources

ED:  Exposure Factors Handbook, 2011 (U.S. EPA), Table 16-108; 90th percentile for current residence time (26 years). Utilized in the U.S. EPA Regional Screening Level (RSL).

IRWchild:  Exposure Factors Handbook, 2011 (U.S. EPA), Tables 3-15 and 3-33; weighted average of 90th percentile consumer-only ingestion of drinking water (birth to less than 6 years of age). Utilized in the U.S. EPA Regional Screening Level (RSL) calculator for a child 0 – 6 years of age.

IRWadult:  Exposure Factors Handbook, 2011 (U.S. EPA), Table 3-33; weighted average of 90th percentile consumer-only ingestion of drinking water (greater than or equal to 21 years of age). Utilized in the U.S. EPA Regional Screening Level (RSL) calculator for an average adult.

BWchild:  Exposure Factors Handbook, 2011 (U.S. EPA), Table 8-1; weighted average of mean body weights (birth to less than 6 years of age). Utilized in the U.S. EPA Regional Screening Level (RSL) calculator for a child 0 – 6 years of age.

BWadult:  Exposure Factors Handbook, 2011 (U.S. EPA), Table 8-3; weighted average of mean body weights (adults 21 – 78). Utilized in the U.S. EPA Regional Screening Level (RSL) calculator for an average adult.

An updated model is also added for carcinogens that operate by a mutagenic mode of action, in order to account for increased cancer risks from childhood exposure:

Updated HNTAC model for mutagens

The age-adjusted drinking water ingestion factor for mutagens (IFWMadj) is an exposure value calculated using an age-adjusted intake factors equation, applying weighted factors of 10, 3 and 1 for age-related exposure concerns. The IFWMadj equals 1,019.9 L/kg:

           

Updated exposure factors for the IFWMadj equation:

SymbolParameterUpdated Value
EF - all (days/year)Exposure Frequency 350
ED0-2 (years)Exposure Duration 0-2 years of age2
IRW0-2 (L/day)Daily Water Ingestion Rate – 0-2 years of age0.78
BW0-2 (kg)Body Weight – 0-2 years of age15
ED2-6 (years)Exposure Duration – ages 2-64
IRW2-6(L/day)Daily Water Ingestion Rate – ages 2-60.78
BW2-6 (kg)Body Weight – ages 2-615
ED6-16 (years)Exposure Duration -  ages 6-1610
IRW6-16 (L/day)Daily Water Ingestion Rate – ages 6-162.5
BW6-16 (kg)Body Weight – ages 6-1680
ED16-26 (year)Exposure Duration – ages 16-2610
IRW16-26 (L/day)Daily Water Ingestion Rate – ages 16-262.5
BW16-26 (kg)Body Weight – ages 16-2680

 

4. Updates Class I groundwater quality standards in tables at Part 620.410, based on updates to toxicity values, exposure factors and other methodologies.

 

5. Updates Class II groundwater quality standards in tables at Part 620.420, based on updates to Class I groundwater quality standards and updates to treatment factors, based on updates to dimensionless Henry's Law values when calculated at 20 oC and organic carbon partition coefficients.

 

6a. Establishes groundwater quality standards for the following chemicals:

CASRNConstituentPlacement in Tables
7429-90-5Aluminum

Part 620.310(a)(3)(A)(ii)

Part 620.410(a)

Part 620.420(a)(2)

7439-93-2Lithium

Part 620.410(a)

Part 620.420(a)(1)

90-12-01-Methylnaphthalene

Part 620.310(a)(3)(A)(ii)

Part 620.410(b)

Part 620.420(b)

7439-98-7Molybdenum

Part 620.310(a)(3)(A)(ii)

Part 620.410(a)

Part 620.420(a)(1)

375-73-5PFBS (perfluorobutanesulfonic acid)

Part 620.310(a)(3)(A)(ii)

Part 620.410(b)

Part 620.420(b)

355-46-4PFHxS (perfluorohexanesulfonic acid)

Part 620.310(a)(3)(A)(ii)

Part 620.410(b)

Part 620.420(b)

375-95-1PFNA (perfluorononanoic acid)

Part 620.310(a)(3)(A)(ii)

Part 620.410(b)

Part 620.420(b)

335-67-1PFOA (perfluorooctanoic acid)

Part 620.410(b)

Part 620.420(b)

1763-23-1PFOS (perfluorooctanesulfonic acid)

Part 620.310(a)(3)(A)(ii)

Part 620.410(b)

Part 620.420(b)

 

6b. Adds the following metabolites as a mixture to atrazine: DEA (desethyl-atrazine), DIA (desisopropyl-atrazine) and DACT (diaminochlorotriazine); and moves atrazine and its metabolites tables at Part 620.410(c)(2) and Part 620.420(c)(2) for complex chemical mixtures.

 

6c. Combines radium 226 and 228, forming CASRN. 7440-14-4: Combined Radium 226+228, and updates the groundwater quality standard from the former MCLs of 20 pCi/L, each, to the U.S. EPA drinking water MCL for combined radium 226+288 of 5 pCi/L. The updates also establish a Class II groundwater quality standard (equal to the Class I standard) for combined radium 226+228 and adds it to the table at Part 620.420(a)(2).  

 

6d. Establishes a Class II groundwater quality standard for silver and adds it to the table at Part 620.420(a)(2).

 

7. Updates constituent tables to include Chemical Abstract Services Registry Numbers (CASRNs) as additional identifiers for the constituents.

 

8. Adds footnotes to tables identifying the sources or methods for determining the groundwater quality standards.

 

9. Removes the explosive constituents at Parts 620.410(c) and 620.420(c); and integrates the constituents into Parts 620.410(b) and 620.420(b).

 

10. Adds Appendix E, providing tables for similar-acting non-carcinogenic constituents by health effect (Table A) and similar-acting carcinogen constituents by cancer effect (Table B).

 

11. Updates the names of the following constituents:

CASRNCurrent Constituent NameUpdated Constituent Name
143-33-9CyanideCyanide (sodium cyanide)
7681-49-4FluorideFluoride (sodium fluoride)
7487-94-7MercuryMercury (mercuric chloride)
78-93-32-Butanone (MEK)2-Butanone (methyl ethyl ketone)
94-75-72,4-D2,4-D (2,4-dichlorophenoxy acetic acid)
96-12-81,2-Dibromo-3-Chloropropane1,2-Dibromo-3-chloropropane (dibromochloropropane)
95-50-1ortho-Dichlorobenzeneo-Dichlorobenzene (1,2-dichlorobenzene)
106-46-7para-Dichlorobenzenep-Dichlorobenzene (1,4-dichlorobenzene)
75-09-2DichloromethaneDichloromethane (methylene chloride)
123-91-1P-Dioxane1,4-Dioxane (p-dioxane)
106-93-4Ethylene DibromideEthylene Dibromide (1,2-dibromoethane)
58-89-9Lindane (gamma-Hexachlorocyclohexane lindane)gamma-HCH (gamma-Hexachlorocyclohexane, lindane)
2691-41-0HMX (High Melting Explosive, Octogen)HMX (octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine)
1634-04-4Methyl Tertiary-Butyl Ether (MTBE)MTBE (methyl tertiary-butyl ether)
95-48-72-Methylphenol2-Methylphenol (o-cresol)
1336-36-3polychlorinated biphenyls (PCBs) (as decachloro-biphenyl)PCBs (polychlorinated biphenyls as decachloro-biphenyl)
121-82-4RDX (Royal Demolition Explosive, Cyclonite)RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine)
118-96-72,4,6-Trinitrotoluene (TNT)TNT (2,4,6-trinitrotoluene)

 

12. Adds carcinogen designations for the following chemicals:            

CASRNConstituentCarcinogen ClassificationClassification Source (year)
106-46-7p-Dichlorobenzene (1,4-dichlorobenzene)2BIARC (1999)
100-41-4Ethylbenzene2BIARC (2000)
58-89-9gamma-HCH (gamma-hexachlorocyclohexane, lindane)1IARC (2018)
98-82-8Isopropylbenzene (cumene)2BIARC (2013)
335-67-1PFOA (perfluorooctanoic acid)2BIARC (2017)

IARC: International Agency for Research on Cancer

 

13. Adds mutagen designations for the following chemicals:

CASRNConstituent
56-55-3Benzo(a)anthracene
205-99-2Benzo(b)fluoranthene
207-08-9Benzo(k)fluoranthene
50-32-8Benzo(a)pyrene
218-01-9Chrysene
53-70-3Dibenzo(a,h)anthracene
96-12-81,2-Dibromo-3-chloropropane (dibromochloropropane)
75-09-2Dichloromethane (methylene chloride)
193-39-5Indeno(1,2,3-c,d)pyrene
79-01-6Trichloroethylene
75-01-4Vinyl Chloride

               

14. Updates oral reference dose toxicity values for the following constituents whose groundwater quality standards are based on the HTTAC equation:

CASRNConstituent

Updated Oral Reference Dose

(RfD)

 mg/kg-day

Updated RfD Source
7440-42-8Boron2E-01IRIS
7440-48-4Cobalt3E-04PPRTV
14797-73-0Perchlorate7E-04IRIS
7440-22-4Silver5E-03IRIS
7440-66-6Zinc3E-01IRIS
99-65-01,3-Dinitrobenzene1E-04IRIS
93-65-2MCPP (Mecoprop)1E-03IRIS
108-95-2Phenol3E-01IRIS
121-82-4RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine)4E-03IRIS

 

15. Updates oral slope factor toxicity values for the following constituents whose groundwater quality standards are based on the HNTAC equations:

CASRNConstituent

Updated Oral Slope Factor (SFo)

( mg/kg-day)-1

Updated SFo Source
319-84-6alpha-BHC (alpha-benzene hexachloride)6.3E+00IRIS
56-55-3Benzo(a)anthracene1.0E-01IRIS
205-99-2Benzo(b)fluoranthene1.0E-01IRIS
207-08-9Benzo(k)fluoranthene1.0E-02IRIS
218-01-9Chrysene1.0E-03IRIS
53-70-3Dibenzo(a,h)anthracene1.0E+00IRIS
121-14-22,4-Dinitrotoluene3.1E-01CalEPA
606-20-02,6-Dinitrotoluene1.5E+00PPRTV
123-91-11,4-Dioxane (p-dioxane)1.0E-01IRIS
193-39-5Indeno(1,2,3-c,d)pyrene1.0E-01IRIS

IRIS = Integrated Risk Information System (National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency)

PPRTV = Provisional Peer-Reviewed Toxicity Value (Superfund Health Risk Technical Support Center, National Center for Environmental Assessment, Office of Research and Development, U.S. Environmental Protection Agency)

CalEPA = Office of Environmental Health Hazard Assessment, California Environmental Protection Agency

 

Proposed Changes to 620 Sub Part A-F

Sub Part SectionProposed Changes
Part A620.110Adds definition of "Chemical Abstract Service Registry Numbers (CASRN)", "Lowest Concentration Minimum Reporting Level", and "Mutagen". Updates definition of "Carcinogen" to be consistent with updates to terminology used by U.S. EPA Integrated Risk Information System, and definition of "Detection" to language currently used in test methods. Removes the definition of "Practical Quantitation Level".
 620.125Updates CFR references to most recent iteration of the code. Adds Illinois EPA "Integrated Water Quality Report and Section 303(d) List" (2016) and National Academy of Science "Water Quality Criteria" (1973) to incorporated references and updates several test methods. Adds references from the U.S. EPA Office of Research and Development, National Center for Environmental Assessment, and reference from U.S. EPA Office of Resource Conservation and Recovery. Updated for groundwater guidance from USEPA 2017. 
Part B620.21Removes permeameter as an acceptable means to determine hydraulic conductivity. Adds the wellhead protection area of a community water supply well or well field as a specific area to which Class I groundwater quality standards are applicable.
 620.250Lists a standard set of documentation that must be included with all groundwater management zone applications.
Part C620.302Adds to the list of examples of persons who do groundwater monitoring.
 620.310Updates table at Part 620.310(a)(3)(A)(i) to include CASRN for each constituent; and removes para-dichlorobenzene and ethylbenzene from the table due to their updated carcinogen classification and the Board Note for 620.310(a)(3)(A). Adds a table at Part 620.310(a)(3)(A)(ii) depicting the constituents in the subsection; and removes gamma-HCH (gamma-hexachlorocyclohexane, lindane) and isopropylbenzene (cumene) due to their updated carcinogen classification and the Board Note for 620.310(a)(3)(A). Amends Board Note for 620.310(a)(3)(A) to revised outdated language.
Part D620.410Adds Class I groundwater quality standards for nine new chemicals. Updates constituent tables to add CASRN for each constituent. Adds footnotes detailing the sources of the standards. Updates Class I groundwater quality standards as applicable. Removes explosive constituents table at 620.410(c) and integrates the constituents into table at 620.410(b). Moves atrazine from 620.410(b) to the complex chemical mixtures tables at 620.410(c) with the addition of atrazine metabolites.
 620.420Adds Class II groundwater quality standards for nine new chemicals and two chemicals listed in 620.410 without prior Class II groundwater quality standards. Updates constituent tables to add a CASRN for each constituent, and update Class II groundwater quality standards as applicable. Adds footnotes detailing the sources of the standards. Removes explosive constituents table at 620.420(c) and integrates the constituents into table at 620.420(b). Moves atrazine from 620.420(b) to the complex chemical mixtures tables at 620.420(c) with the addition of atrazine metabolites.
 620.430Establishes site specific Class III groundwater quality standards for chloride and pH at four dedicated nature preserves, which are caves, pursuant to 620.230(b). Establishes site specific Class III groundwater quality standards for chloride at two dedicated nature preserves, which are wetlands, pursuant to 620.230(b).
 620.440Updates names of explosive constituents.
 620.450Updates names of explosive constituents.
Part E620.510Requires that the 2009 Unified Guidance be used to determine background groundwater quality unless other methods are specified by regulation. Replaces the use of the PQL with the LLOQ, LCMRL or MDL, as appropriate to the nature of the chemical.
Part F620.601(b)-Updates code reference to 604.200.
 620.605(b)(1) Designates the more stringent toxicity value of the (Human Threshold Toxicant Advisory Concentration (HTTAC) or Human Nonthreshold Toxicant Advisory Concentration (HNTAC) as the guidance value in the absence of a Maximum Contaminant Level (MCL) or Maximum Contaminant Level Goal (MCLG).
  (b)(2) Removes the Human Nonthreshold Toxicant Advisory Concentration (HNTAC) language and equation and relocates it to Appendix A.

 

Proposed Changes to 620 Appendices

AppendixSectionProposed Changes
A(a)Updates exposure factors representative of a child for the HTTAC model, which is consistent with Illinois Administrative Code Part 742 and U.S. EPA Regional Screening Levels (per capita daily water consumption = 0.78 liters per day, assumed average weight of a child 0-6 years of age = 15 kg).
 (b)(2)Incorporates U.S. EPA's hierarchy of toxicity sources from "Tier 3 Toxicity Value White Paper", dated May 16, 2013, by U.S. EPA Office of Solid Waste and Emergency Response Human Health Regional Risk Assessors Forum (OSWER) for determining an appropriate verified oral reference dose.
 (b)(3)Revises methodology used to calculate guidance values when a verified oral reference dose is not available to make language consistent with U.S. EPA Reference Dose Guidance.
 (b)(4)Clarifies usage of uncertainty factors.
 (c)(1)Adds equation for calculating HNTAC guidance level for chemicals designated as mutagens.
 (c)(2)Updates equation for calculating HNTAC guidance levels for chemicals designated as carcinogens that are not designated as mutagens.
B(c)Removes language specific to mixtures of ortho-dichlorobenzene and para-dichlorobenzene, and 1,1-dichloroethane and 1,1,1-trichloroethane, and adds reference to Appendix E.
E Provides tables of similar acting non-carcinogenic and carcinogenic constituents.