R97012A.PDF

ILLINOIS POLLUTION CONTROL BOARD

October 2, 1997

IN THE MATTER OF:

TIERED APPROACH TO CORRECTIVE

ACTION OBJECTIVES (TACO):

AMENDMENTS TO 35 ILL.

ADM. CODE 742.105, 742.200, 742.505,

742.805, and 742.915

)

R97-12(B)

(Rulemaking - Land)

Proposed Rule. Second Notice.

OPINION AND ORDER OF THE BOARD (by M. McFawn and J. Yi)

The Board proposes today for second notice amendments to 35 Ill. Adm. Code 742:

Tiered Approach to Corrective Action Objectives, also known as TACO. The amendments

address how the effect of similar-acting chemicals on the same target organ (also know as the

mixture rule) is to be taken into account when determining remediation objectives under

TACO. Specifically, the amendments consider the effects of similar-acting chemicals,

i.e.,

carcinogens and noncarcinogens, under Tiers 1, 2, and 3 of the TACO process. The statutory

premise for the mixture rule is found at Section 58.5(c) of the Illinois Environmental

Protection Act (Act) (415 ILCS 5/58.5(c) (1996)) and 35 Ill. Adm. Code 620 of the Board’s

regulations. Section 58.5(c) of the Act provides in pertinent part that the regulations

establishing remediation objectives shall address “the presence of multiple substances of

concern and multiple exposure pathways.” 415 ILCS 5/58.5(c) (1996). Section 620.615 of

the Board’s regulations requires that the Agency determine “the need for additional health

advice appropriate to site-specific conditions” when similar-acting chemicals are detected. 35

Ill. Adm. Code 620.615. The amendments were originally proposed by the Agency during the

course of Docket A of this rulemaking.

On April 17, 1997, the Board opened this Docket B to fully consider the type and to

what extent a mixture rule is necessary under TACO to protect human health. Public hearings

were held on May 21, 1997, and May 29, 1997, to consider the proposal of the Illinois

Environmental Protection Agency (Agency). On July 10, 1997, the Board proceeded to first

notice, pursuant to the Illinois Administrative Procedure Act (APA) (5 ILCS 100/1-1 (1996)).

Subsequently, on July 25, 1997, the amendments to Part 742 were published in the

Illinois

Register

(21 Ill. Reg. 9687 (July 25, 1997)), upon which a 45-day comment period began.

The first notice comment period ended on September 8, 1997. No public comments

were received during the first notice period, however, one public comment was received just

prior to its initiation. The Site Remediation Advisory Committee (SRAC) filed a motion to

See Tiered Approach to Corrective Action Objectives (TACO): 35 Ill. Adm. Code 742 (June

5, 1997), R97-12(A) (effective July 1, 1997).

file instanter and supplemental post-hearing comments on July 15, 1997 (PC 3

). The Board

hereby grants the SRAC’s motion and considers its supplemental post-hearing comments in this

second notice opinion.

Today the Board adopts the amendments to Part 742, unchanged from first notice, for

the purpose of second notice pursuant to the APA. The amendments will be submitted to the

Joint Committee on Administrative Rules for its consideration. The mixture rule is adopted

for second notice for each of the three tiers. The mixture rule under Tier 1 applies to

carcinogens and noncarcinogens detected in groundwater. There is no rule applicable to

contaminants of concern in soil at Tier 1 sites. The mixture rule under Tier 2 applies to both

carcinogens and noncarcinogens in groundwater, but only to noncarinogens in soil. Finally,

the mixture rule under Tier 3 applies to both carcinogens and noncarcinogens in both

groundwater and soil. Also adopted today is the definition of “similar-acting chemicals” and

Appendix A.Table H which lists carcinogens with groundwater remediation objectives based

on concentrations in excess of 1 in 1,000,000 cancer risk.

ANALYSIS

Definition of Similar-Acting Chemical

The Board proposed at first notice to adopt at Section 742.200 a definition of similar-

acting chemicals. There was no such definition in the final rules adopted under Docket A

because the term was defined within Sections 742.710 and 742.805(c). In response to public

testimony, the Board proposed that, at Section 742.200, the following definition of “similar-

acting chemicals” be inserted:

“Similar-Acting Chemicals” are chemical substances that have toxic or harmful

physiological effect on the same specific organ or organ system. (See Appendix

A.Tables E and F, for a list of similar-acting chemicals with noncarcinogenic

and carcinogenic effects.)

As stated in its first notice opinion, the Board finds that this definition parallels the

description of similar-acting chemicals found at 35 Ill. Adm. Code 620.615. Since the

mixture rule originates from that rule, the Board finds that its description of similar-acting

chemicals is most appropriate for defining the same under TACO.

Appendix A.Table H: Carcinogens with Groundwater Remediation Objectives in Excess of a

1 in 1,000,000 Cancer Risk Concentration

Docket B public comments and exhibits will be referred to as PC at __ and Exh. 1 at __,

respectively; the May 21, 1997 hearing will be referred to as Tr.1 at __; the May 29, 1997

hearing will be referred to as Tr.2 at __.

In its prefiled testimony under Docket B, the Agency proposed that a new Table H be

added to Part 742 in Appendix A. Exh.1 at 10. Table H lists those chemicals whose Tier 1

Class I groundwater remediation objectives exceed the 1 in 1,000,000 cancer risk

concentrations and therefore must undergo either the Tier 2 or Tier 3 procedure for evaluating

the mixture effect of similar-acting chemicals. At first notice, the Board agreed with the

Agency that the new Appendix A.Table H will assist the remediation applicant to more readily

determine whether the similar-acting carcinogenic chemicals detected are subject to the mixture

rule found under Tier 2 or 3. The Board continues to agree with the Agency that this new

table will aid the remediation applicant when applying the mixture rule in the TACO process.

Satisfaction of Section 620.615 of the Board’s Groundwater Regulations

In its prefiled testimony before first notice, the Agency proposed that the Board adopt

language that the “requirements of 35 Ill. Adm. Code 620.615 regarding mixtures of similar-

acting chemicals shall be considered met for Class I groundwater at the point of human

exposure” if certain requirements under Tier 1 and Tier 2, respectively, are achieved. Exh. 2

at 4-5. Those requirements are (1) that the level of the contaminant of concern does not

exceed the Tier 1 remediation objective, and (2) that the remediation objective is based on a

risk level of 1 in 1,000,000. Because we adopted a mixture rule for both similar-acting

carcinogenic and noncarcinogenic chemicals under all three tiers, the Board at first notice

accepted the Agency’s premise, but modified the language it proposed with the amendments

adopted at first notice.

Accordingly, the language proposed at first notice at both Tiers 1 and 2 provides that

the evaluation required under Section 620.615 shall be considered satisfied, subject to two

exceptions. First, under all three tiers if more than one similar-acting noncarcinogenic

chemical is detected at the site, the mixture rule set out at Section 742.805(c) or that developed

under Tier 3 must be applied. Second, if a similar-acting carcinogenic chemical listed on

Appendix A.Table H is detected at the site, the mixture rule at Section 742.805(d) or that

developed under Tier 3 must be applied. The Board finds that compliance with one of the

applicable mixture rules under TACO serves to satisfy the statutory requirement that multiple

chemicals be addressed. Further, the Board finds that the mixture rule serves as an appropriate

alternative procedure to that set out at Section 620.615.

Prior to Docket B, the Agency requested that the mixture rule apply to both

carcinogens and noncarcinogens to ensure that Section 620.615 is satisfied under TACO. The

Agency now requests that the mixture rule only apply to similar-acting carcinogens in

groundwater under Tier 1. The Agency’s rationale for changing its position is that, as a matter

of policy, a “look-up table” is preferable to a mixture rule, and therefore, the Agency is

willing to forgo such a rule since no such table can be created for noncarcinogens. The

Agency never explained the risk difference between carcinogens and noncarcinogens,

i.e.

, why

it believes Section 620.615 could be deemed satisfied absent such a rule when similar-acting

noncarcinogens are detected in groundwater. The only difference appears to be the ability to

devise a “look-up table” for carcinogens. The Board did not agree with the Agency that the

Act and Section 620.615 can be deemed satisfied unless the cumulative affect of similar-acting

chemicals is evaluated in all cases. We found that TACO and Section 620.615 would not be

comparable if similar-acting noncarcinogenic chemicals in groundwater are not subject to the

mixture rule under Tier 1. Therefore, we made all similar-acting contaminants subject to the

mixture rule under Tier 1. See Tiered Approach to Corrective Action Objectives (TACO):

Amendments to 35 Ill. Adm. Code 742.105, 742.200, 742.505, 742.805, and 742.915 (July

10, 1997), R97-12(B), slip op. at 8-9, 13.

The Board also modified the Agency’s proposed language. Those principle

modifications include substituting (1) “the requirements of Section 620.615” with the term

“evaluations” and (2) “shall be considered met” with the term “satisfied”. The Board

believed these substitutions more accurately reflect the appropriate cross-reference and

relationship between the two rules. See Sections 742.505(b)(3) and 742.805(c) and (d); Tiered

Approach to Corrective Action Objectives (TACO): Amendments to 742.105, 742.200,

742.505, 742.805, and 742.915 (July 10, 1997), R97-12(B), slip op. at 9.

Tier 1

In Docket A on June 5, 1997, the Board adopted a mixture rule at Section 742.505(b)

that is applicable only to noncarcinogenic chemicals for groundwater remediation objectives

under Tier 1, regardless of whether the Tier 1 remediation objectives were exceeded. See

Tiered Approach to Corrective Action Objectives (TACO): Amendments to 742.105,

742.200, 742.505, 742.805, and 742.915 (June 5, 1997), R97-12(B). The Board did not

adopt a mixture rule for similar-acting carcinogens in groundwater because the record did not

support the same. See Tiered Approach to Corrective Action Objectives (TACO):

Amendments to 742.105, 742.200, 742.505, 742.805, and 742.915 (June 5, 1997), R97-

12(B), slip op. at 19.

Based on the evidence presented to the Board by the Agency in Dockets A and B, the

Board found at first notice (1) that a mixture rule is not necessary for either carcinogenic or

noncarcinogenic chemicals when developing soil remediation objectives under Tier 1, and (2)

that a mixture rule is necessary for both similar-acting carcinogenic and noncarcinogenic

chemicals when developing groundwater remediation objectives under Tier 1. Accordingly,

the current rule at Section 742.505(b) that similar-acting noncarcinogenic chemicals be

evaluated under Tier 1 for groundwater was retained, but amended to include the same

requirement for similar-acting carcinogenic chemicals when the Tier 1 remediation objectives

are exceeded or when similar-acting carcinogenic chemicals have remediation objectives set at

risk levels higher than 1 in 1,000,000. We adopt for second notice the same mixture rule for a

Tier 1 analysis.

Soil

With regard to Tier 1 soil remediation objectives, Dr. Hornshaw testified at hearing

that the inherent protection built into the process of developing the Tier 1 soil remediation

objectives, for similar-acting carcinogenic and noncarcinogen, made consideration of the

additivity of effects of similar-acting chemicals unnecessary in Tier 1. Tr.1 at 14, 19.

Therefore, Dr. Hornshaw testified that the remediation objectives set forth in Appendix

A.Tables E and F are protective of human health in the context of soil remediation objectives.

Groundwater

In Docket A, the Agency advocated that the Board adopt a mixture rule for both

similar-acting noncarcinogens and carcinogens in groundwater. In Docket B, however, the

Agency advocated such a rule for carcinogens only. At hearing, Dr. Hornshaw testified that,

initially, the Agency and the SRAC agreed that consideration of mixtures of similar-acting

chemicals is not necessary under Tier 1 but for those carcinogens whose groundwater

remediation objectives are not based on a 1 in 1,000,000 cancer risk. Tr.1 at 23.

In support of this agreement, the Agency explained that, unlike the Tier 1 soil

remediation objectives, there is not necessarily the same degree of protection built into the

groundwater remediation objectives. Tr.1 at 21. Dr. Hornshaw argued that the only

conservatisms built into development of the remediation objectives for groundwater are

assumptions regarding the toxicity and the actual intake of the chemical. Tr.1 at 21-22.

Further, Dr. Hornshaw maintained that, for certain similar-acting carcinogenic chemicals

whose Tier 1 groundwater remediation objective are based on the chemical’s drinking water

standard, the groundwater remediation objectives do not have the same degree of conservatism

as the corresponding soil remediation objectives. Tr.1 at 22. For that reason, the Agency

only advocated that similar-acting carcinogens be subject to a mixture rule under Tier 1.

At hearing, the SRAC witness agreed with the Agency. Mr. Harry Walton, testifying

on behalf of the SRAC, maintained that the mixture rule need not be applicable under Tier 1 to

noncarcinogens in groundwater because the site cleanup will be driven by carcinogens. Tr.2 at

44-45, 49. The example relied upon by Mr. Walton and other participants was a site where

benzene, toluene, ethyl benzene, and xylene are present. Mr. Walton testified that similar-

acting noncarcinogenic chemicals will be cleaned up to acceptable levels coincidental to the

benzene cleanup. Tr.2 at 44-45, 49.

At first notice, we agreed with the Agency in part. We adopted a proposed mixture

rule for carcinogens under Tier 1. However, the Board also found that a mixture rule is

necessary for similar-acting noncarcinogenic chemicals when developing groundwater

remediation objectives. The Board noted that it sympathized with the desire by the Agency

and the participants for the simplicity of “look-up tables” under Tier 1. However, the Agency

and the participants agreed that under Tier 1 more than a simple look-up table is necessary

when determining groundwater remediation objectives for similar-acting carcinogenic

chemicals which exceed the high end of the statutory risk range of 1 in 1,000,000 cancer risk.

We concluded that, likewise, the evidence does not support a simple look-up table when the

cumulative effect of similar-acting noncarcinogenic chemicals in groundwater exceeds the

hazard quotient/index of one. Furthermore, we found that the burden on a remediation

applicant to determine the cumulative effect of similar-acting noncarcinogenic chemicals and to

correct the remediation objectives as necessary is not unduly burdensome. For instance, in the

example most used by the participants at hearing, including the SRAC’s witness, Mr. Walton,

the only additional burden on the remediation applicant will be to perform the necessary

calculations to determine the cumulative effect and the corrected remediation objectives, and

prove that the latter were achieved as part of the benzene remediation. See Tiered Approach

to Corrective Objectives (TACO) (July 10, 1997), R97-12(B), slip op. at 9-13 for additional

discussion.

In its supplemental post-hearing comments (received after adoption of the July 10, 1997

first notice opinion and order), the SRAC reiterated the arguments it made at hearing why a

mixture rule is unnecessary when determining remediation objectives for groundwater under

Tier 1. PC 3 at 2. First, the SRAC asserts that Part 620 and Part 742 were developed in

different contexts for different purposes. PC 3 at 2. The SRAC maintains that Part 620 was

developed as statewide standards, without limited consideration of site specific conditions, and

those standards were not intended to be imposed as remedial standards in the context of a

remediation program. PC 3 at 2. The SRAC argues that, on the other hand, Part 742 is

intended for use in context with various remediation programs to establish remediation

objectives appropriate for a specific site. PC 3 at 3. Next the SRAC argues that a mixture

rule is unnecessary because Part 742 requires sources of contamination be removed and/or

controls installed in addition to the conservatism of the Tier 1 numbers. PC 3 at 3-4.

Moreover, the SRAC again argues that in its practical application, mixtures of similar-acting

chemicals will not be the driving force of TACO remediations. PC 3 at 4. Finally, the SRAC

argues that Section 58.5(d)(1) of the Act mandates that Tier 1 remediation objectives be

expressed as a table of numeric value for soil and groundwater objectives and that to do

otherwise would be contrary to the language and intent of the authorizing legislation. PC 3 at

4-5.

For the most part, the Board has already addressed these arguments in the first notice

opinion and order because Mr. Walton had testified to the same at hearing on May 29, 1997.

However, two arguments warrant further discussion. They are the following two arguments

made in the SRAC’s supplemental post-hearing comment. First, the SRAC argues that Section

58.5(d)(1) of the Act (415 ILCS 5/58.5(d)(1) (1996)) mandates numeric tables for Tier 1

remediation objectives. PC 3 at 4. Second, the SRAC argues that the Part 620 groundwater

quality standards were established for statewide applicability and were never intended to be

imposed as remedial standards in the context of a remediation program. PC 3 at 2.

As to the SRAC’s statutory argument, the Board recognizes that Section 58.5(d) of the

Act requires that:

[a]t a minimum, the objectives shall include the following:

Tier 1 remediation objectives expressed as a table of numeric

values for soil and groundwater. (Emphasis added.) 415 ILCS

5/58.5(d) (1996).

Such tables were adopted in Docket A. Specifically, the numerical groundwater remediation

objectives are found at Appendix B.Table E. We also recognize that Section 58.5(c)(4) of the

Act provides in pertinent part that:

The methodologies adopted under this Section shall ensure that

the following factors are taken into account in determining

remediation objectives:

potential risks posed by carcinogens and noncarcinogens;

and

the presence of multiple substances of concern and

multiple exposure pathways. (Emphasis added.) 415

ILCS 5/58.5(c)(4) (1996).

We have concluded that both statutory provisions can be satisfied, and are not

irreconcilable when read together. Furthermore, we have concluded that more than a numeric

table is necessary to determine the groundwater remediation objectives for similar-acting

carcinogens,

i.e.

, that a mixture rule must be applied. The Agency testified that it and other

participants have agreed that this is necessary to properly manage the risk posed by the similar-

acting chemicals at a site. Tr.1 at 21-22; Tr.2 at 36-37. At hearing, no one argued that

Section 58.5(d) of the Act prohibits this approach. And, in the context of similar-acting

noncarcinogens, the Agency did not argue that a mixture rule is contrary to Section 58.5(d).

Instead, it explained that it wants to preserve the user-friendly approach a numeric table

affords. The Board finds that the mandate of Section 58.5(c) prevails over the Agency’s policy

argument, and a mixture rule is necessary to protect human health. As for the statutory

argument made by the SRAC, we do not agree that a mixture rule is contrary to the language

or intent of Section 58.5 of the Act when read in its entirety.

The SRAC’s second argument is that the Part 620 groundwater quality standards were

established for statewide applicability, “without limited consideration of site-specific

conditions.” PC 3 at 2. Yet Section 620.615 requires the Agency to take into account “the

need for additional health advice appropriate to site-specific conditions” (emphasis added)

when similar-acting chemicals are detected. In any event, the Part 620 groundwater quality

standards were adopted as remediation objectives in this rulemaking. They are the remediation

objectives at Appendix B.Table E to be applied on a site-specific basis. Under Part 620,

specifically Section 620.615, the groundwater quality standards are subject to a mixture rule

when site-specific groundwater conditions so required. So that these numerical values under

TACO are equally protective, the mixture rule is necessary. The mixture rule assures that the

cumulative effect of similar-acting chemicals is evaluated, and the applicable remediation

objectives are corrected to a level which does not pose a risk to human health. This is equally

true for both similar-acting carcinogens and noncarcinogens. Neither the Agency nor the

SRAC has explained why levels of similar-acting noncarcinogens in excess of the hazard

quotient/index do not pose a risk to public health. They simply argue that remediation

objectives are sufficiently conservative. However, absent such a rule, contamination at the site

could remain at a level in excess of the hazard quotient of one – the value at which a chemical

exposure is measured to be greater than the reference dose. The reference dose is the

acceptable daily chemical exposure at which no harmful consequences occur. See Section

742.200 (definition of “reference dose”); Tr.2 at 29-31.

Tier 2

Under Docket A, the adopted mixture rule is applicable only for similar-acting

noncarcinogenic chemicals in the context of both groundwater and soil remediation objectives.

The Board did not adopt a mixture rule for similar-acting carcinogenic chemicals because the

record did not support the same. Tiered Approach to Corrective Action Objectives (TACO):

Amendments to 742.105, 742.200, 742.505, 742.805, and 742.915 (June 5, 1997), R97-

12(A) slip. op. at 49-50.

The Agency’s position under Docket B is that a mixture rule for similar-acting

noncarcinogenic chemicals is still necessary for soil and groundwater remediation objectives,

but maintains that the only mixture rule necessary for similar-acting carcinogenic chemicals is

in the context of groundwater remediation objectives. Based upon the evidence presented by

the Agency, the Board agrees with the Agency’s analysis and conclusions regarding this issue.

Accordingly, the mixture rule proposed under Tier 2 which applies to similar-acting

noncarcinogenic chemicals is also retained, but amended to require that the cumulative effect

of similar-acting carcinogenic chemicals be evaluated when developing groundwater

remediation objectives. However, the Tier 2 mixture rule for soil remediation objectives

remains unchanged, applicable only to similar-acting noncarcinogenic chemicals. A brief

summary of that evidence follows.

Soil

As for mixtures of similar-acting chemicals in soil under Tier 1 or 2, Dr. Hornshaw

testified at hearing that it was only necessary to address mixture effects of similar-acting

noncarcinogenic chemicals because, for similar-acting carcinogenic chemicals, the language of

Section 58.5(d) of the Act specifically provides for the establishment of remediation objectives

at an excess lifetime cancer risk of between 1 in 10,000 and 1 in 1,000,000. Tr.1 at 15. Dr.

Hornshaw further explained that the Agency and the SRAC were in agreement that, “since the

statute provides for an acceptable cancer risk range and since even if there are 10 carcinogens

present at their respective 1 in 1,000,000 remediation objectives (an unusual event), the

cumulative cancer risk of 1 in 100,000 is still within an acceptable range.” Tr.1 at 15. On

the other hand, because the Act does not specify an acceptable risk range for similar-acting

noncarcinogenic chemicals, Dr. Hornshaw concluded that the additive effects of similar-acting

noncarcinogenic chemicals need to be considered and provided for under Tier 2. Tr.1 at 15,

19.

Groundwater

With regard to mixtures of similar-acting carcinogenic chemicals in groundwater under

Tier 2, the Agency maintained that there are similar-acting carcinogenic chemicals whose

groundwater objectives exceed the 1 in 1,000,000 cancer risk level, and which, if present in a

mixture with other similar-acting carcinogenic chemicals, could potentially result in a

cumulative cancer risk exceeding 1 in 10,000. Tr.1 at 24. The Agency maintained that, given

the statutory and regulatory requirements to consider mixture effects in groundwater, the

mixture rule should be applied to Tier 2 mixtures of similar-acting carcinogenic chemicals.

Tr.1 at 22-23. Accordingly, the Agency concluded that similar-acting carcinogenic chemicals

whose Tier 1 groundwater objectives exceed the 1 in 1,000,000 risk level must be evaluated

for mixture effects under Tier 2. Tr.1 at 24. To facilitate such an evaluation, the Agency

proposed that those similar-acting carcinogenic chemicals whose Tier 1 groundwater

remediation objectives exceed the 1 in 1,000,000 risk level will be specifically identified in a

look-up table. Tr.1 at 24; See Exh. 1, Appendix A, Table H. The Agency also testified that

those similar-acting carcinogenic chemicals whose Tier 1 groundwater remediation objectives

are not based on a 1 in 1,000,000 risk level should be subject to the mixture rule. Tr.1 at 24.

As for mixtures of similar-acting noncarcinogenic chemicals in groundwater, Dr.

Hornshaw testified that the Agency and the SRAC agreed that consideration of similar-acting

noncarcinogenic chemicals in Tier 2 is required. Tr.1 at 20.

Tier 3

Under Docket A, no mixture rule was adopted under Tier 3. Under Docket B, the

Agency requested the mixture rule apply to both soil and groundwater remediation objectives

for both similar-acting carcinogenic and noncarcinogenic chemicals. Tr.1 at 19, 27. The

Agency proposed the following language towards that end:

Contaminants of concern which affect the same target organ, organ system or

similar mode of action shall be specifically addressed. At a minimum, the

chemical subject to this requirement are identified in Appendix A, Tables E and

The Board proposed for first notice at Section 742.915(h) the amendments requested

under Tier 3 by the Agency to ensure that the cumulative effects of both carcinogenic and

noncarcinogenic chemicals are evaluated under the Tier 3 site-specific approach.

At the close of its first notice opinion, the Board questioned why the proposed language

does not parallel more closely that requested under Tiers 1 and 2. The Board suggested that

the mixture rule under Tier 3 (1) use the term “similar-acting chemical;” (2) provide minimum

requirements for specifically addressing the cumulative effects of similar-acting chemicals, be

they similar-acting carcinogenic or noncarcinogenic chemicals; and (3) that compliance with

those minimum requirements be deemed protective of Class I groundwater in terms of human

health. The term “similar-acting chemicals” was substituted but Section 742.915(e) was not

otherwise amended at first notice. Finally, the Board asked the Agency and the participants to

consider and comment on these suggested revisions. No comments were received. We will

therefore not change the rule from that proposed at first notice.

CONCLUSIONS

The Board proposes for second notice the same mixture rule as that proposed for first

notice. The mixture rule for similar-acting chemicals in soil is graduated. At Tier 1, it is not

applicable. At Tier 2, it is applicable to noncarcinogens only. And, at Tier 3, it is applicable

to carcinogens and noncarcinogens. The mixture rule for similar-acting chemicals in Class I

groundwater uniformly spans all three tiers of TACO. It is applicable to both similar-acting

carcinogens and noncarcinogens under all three tiers. The mixture rule is basically that

proposed by the Agency with one exception. That exception is that the mixture rule under

Tier 1 applies to similar-acting noncarcinogenic chemicals as well as similar-acting carcinogens

detected in groundwater at sites.

Further, the Board concludes, as we did at first notice, that a mixture rule for similar-

acting noncarcinogenic chemicals in groundwater is required under Tier 1, as well as under

Tiers 2 and 3, because the remediation objective for similar-acting noncarcinogenic chemicals

in groundwater is premised upon a hazard quotient of one. Finally, having proposed the

mixture rule to be all-inclusive, the Board adopts the cross-reference to Section 620.615 of the

Board’s groundwater rules. Thus, the remediation applicant and the public are assured that an

evaluation of similar-acting chemicals provided thereunder is also provided under TACO.

ORDER

The Board directs the Clerk to cause the submission of the following proposal to the Joint

Committee on Administrative Rules:

TITLE 35: ENVIRONMENTAL PROTECTION

SUBTITLE G: WASTE DISPOSAL

CHAPTER I: POLLUTION CONTROL BOARD

SUBCHAPTER f: RISK BASED CLEANUP OBJECTIVES

PART 742

TIERED APPROACH TO CORRECTIVE ACTION OBJECTIVES

SUBPART A: INTRODUCTION

Section

742.100

Intent and Purpose

742.105

Applicability

742.110

Overview of Tiered Approach

742.115

Key Elements

742.120

Site Characterization

SUBPART B: GENERAL

Section

742.200

Definitions

742.205

Severability

742.210

Incorporations by Reference

742.215

Determination of Soil Attenuation Capacity

742.220

Determination of Soil Saturation Limit

742.225

Demonstration of Compliance with Remediation Objectives

742.230

Agency Review and Approval

SUBPART C: EXPOSURE ROUTE EVALUATIONS

Section

742.300

Exclusion of Exposure Route

742.305

Contaminant Source and Free Product Determination

742.310

Inhalation Exposure Route

742.315

Soil Ingestion Exposure Route

742.320

Groundwater Ingestion Exposure Route

SUBPART D: DETERMINING AREA BACKGROUND

Section

742.400

Area Background

742.405

Determination of Area Background for Soil

742.410

Determination of Area Background for Groundwater

742.415

Use of Area Background Concentrations

SUBPART E: TIER 1 EVALUATION

Section

742.500

Tier 1 Evaluation Overview

742.505

Tier 1 Soil and Groundwater Remediation Objectives

742.510

Tier 1 Remediation Objectives

SUBPART F: TIER 2 GENERAL EVALUATION

Section

742.600

Tier 2 Evaluation Overview

742.605

Land Use

742.610

Chemical and Site Properties

SUBPART G: TIER 2 SOIL EVALUATION

Section

742.700

Tier 2 Soil Evaluation Overview

742.705

Parameters for Soil Remediation Objective Equations

742.710

SSL Soil Equations

742.715

RBCA Soil Equations

742.720

Chemicals with Cumulative Noncarcinogenic Effects

SUBPART H: TIER 2 GROUNDWATER EVALUATION

Section

742.800

Tier 2 Groundwater Evaluation Overview

742.805

Tier 2 Groundwater Remediation Objectives

742.810

Calculations to Predict Impacts from Remaining Groundwater Contamination

SUBPART I: TIER 3 EVALUATION

Section

742.900

Tier 3 Evaluation Overview

742.905

Modifications of Parameters

742.910

Alternative Models

742.915

Formal Risk Assessments

742.920

Impractical Remediation

742.925

Exposure Routes

742.930

Derivation of Toxicological Data

SUBPART J: INSTITUTIONAL CONTROLS

Section

742.1000

Institutional Controls

742.1005

No Further Remediation Letters

742.1010

Restrictive Covenants, Deed Restrictions and Negative Easements

742.1015

Ordinances

742.1020

Highway Authority Agreements

SUBPART K: ENGINEERED BARRIERS

Section

742.1100

Engineered Barriers

742.1105

Engineered Barrier Requirements

APPENDIX A

General

ILLUSTRATION A

Developing Soil Remediation Objectives Under the Tiered

Approach

ILLUSTRATION B

Developing Groundwater Remediation Objectives Under the

Tiered Approach

Table A

Soil Saturation Limits (C

sat

) for Chemicals Whose Melting Point is Less

Than 30

Table B

Tolerance Factor (K)

Table C

Coefficients {A

N-I+1

} for W Test of Normality, for N=2(1)50

Table D

Percentage Points of the W Test for N=3(1)50

Table E

Similar-Acting Noncarcinogenic Chemicals with Noncarcinogenic Toxic

Effects on Specific Target Organs/Organ Systems or Similar Modes of

Action

Table F

Similar-Acting Carcinogenic Chemicals with Carcinogenic Toxic Effects

on Specific Target Organs/Organ Systems or Similar Modes of Action

Table G

Concentrations of Inorganic Chemicals in Background Soils

Table H Chemicals Whose Tier 1 Class I Groundwater Remediation Objective

Exceeds the 1 in 1,000,000 Cancer Risk Concentration

APPENDIX B

Tier 1 Tables and Illustrations

ILLUSTRATION A

Tier 1 Evaluation

Table A

Tier 1 Soil Remediation Objectives for Residential Properties

Table B

Tier 1 Soil Remediation Objectives for Industrial/Commercial Properties

Table C

pH Specific Soil Remediation Objectives for Inorganics and Ionizing

Organics for the Soil Component of the Groundwater Ingestion Route

(Class I Groundwater)

Table D

pH Specific Soil Remediation Objectives for Inorganics and Ionizing

Organics for the Soil Component of the Groundwater Ingestion Route

(Class II Groundwater)

Table E

Tier 1 Groundwater Remediation Objectives for the Groundwater

Component of the Groundwater Ingestion Route

Table F

Values Used to Calculate the Tier 1 Soil Remediation Objectives for the

Soil Component of the Groundwater Ingestion Route

APPENDIX C

Tier 2 Tables and Illustrations

ILLUSTRATION A

Tier 2 Evaluation for Soil

ILLUSTRATION B

Tier 2 Evaluation for Groundwater

ILLUSTRATION C

US Department of Agriculture Soil Texture Classification

Table A

SSL Equations

Table B

SSL Parameters

Table C

RBCA Equations

Table D

RBCA Parameters

Table E

Default Physical and Chemical Parameters

Table F

Methods for Determining Physical Soil Parameters

Table G

Error Function (erf)

Table H

Q/C Values by Source Area

Table I

[oc]

Values for Ionizing Organics as a Function of pH (cm(3)/g or L/kg)

Table J

Values to be Substituted for k

When Evaluating Inorganics as a Function

of pH (cm(3)[water]/g[soil])

Table K

Parameter Estimates for Calculating Water-Filled Soil Porosity (

)

AUTHORITY: Implementing Sections 22.4, 22.12, Title XVI, and Title XVII and authorized

by Sections 27, 57.14, and 58.5 of the Environmental Protection Act [415 ILCS 5/22.4,

22.12, 27, 57.14 and 58.5 and Title XVI and Title XVII] (see P.A. 88-496, effective

September 13, 1993 and P.A. 89-0431, effective December 15, 1995).

MAIN SOURCE: Adopted at 21 Ill. Reg. 7942, effective July 1, 1997, amended at 21 Ill.

Reg. __________________, effective __________________.

NOTE: Capitalization indicates statutory language.

SUBPART A: INTRODUCTION

Section 742.105

Applicability

Any person, including a person required to perform an investigation pursuant to

the Illinois Environmental Protection Act (415 ILCS 5/1 et seq.) (Act), may

elect to proceed under this Part to the extent allowed by State or federal law and

regulations and the provisions of this Part. A person proceeding under this Part

may do so to the extent such actions are consistent with the requirements of the

program under which site remediation is being addressed.

This Part is to be used in conjunction with the procedures and requirements

applicable to the following programs:

Leaking Underground Storage Tanks (35 Ill. Adm. Code 731 and 732);

Site Remediation Program (35 Ill. Adm. Code 740); and

RCRA Part B Permits and Closure Plans (35 Ill. Adm. Code 724 and

725).

The procedures in this Part may not be used if their use would delay response

action to address imminent and substantial threats to human health and the

environment. This Part may only be used after actions to address such threats

have been completed.

This Part may be used to develop remediation objectives to protect surface

waters, sediments or ecological concerns, when consistent with the regulations

of other programs, and as approved by the Agency.

A no further remediation determination issued by the Agency prior to July 1,

1997 pursuant to Section 4(y) of the Act or one of the programs listed in

subsection (b) of this Section that approves completion of remedial action

relative to a release shall remain in effect in accordance with the terms of that

determination.

Site specific groundwater remediation objectives determined under this Part for

contaminants of concern may exceed the groundwater quality standards

established pursuant to the rules promulgated under the Illinois Groundwater

Protection Act. [415 ILCS 55] as long as done in accordance with Sections

742.805(a) and 742.900(c)(9). (See 415 ILCS 5/58.5(d)(4)

Where contaminants of concern include polychlorinated byphenyls (PCBs), a

person may need to evaluate the applicability of regulations adopted under the

Toxic Substances Control Act (15 U.S.C. 2601).

SOURCE: Amended at 21 Ill. Reg. ______________ , effective __________________.

SUBPART B: GENERAL

Section 742.200

Definitions

Except as stated in this Section, or unless a different meaning of a word or term is clear

from the context, the definition of words or terms in this Part shall be the same as that applied

to the same words or terms in the Act.

“Act” means the Illinois Environmental Protection Act [415 ILCS 5/1 et seq.].

“ADL” means Acceptable Detection Limit, which is the detectable

concentration of a substance which is equal to the lowest appropriate Practical

Quantitation Limit (PQL) as defined in this Section.

“Agency” means the Illinois Environmental Protection Agency.

“Agricultural Property” means any real property for which its present or post-

remediation use is for growing agricultural crops for food or feed either as

harvested crops, cover crops or as pasture. This definition includes, but is not

limited to, properties used for confinement or grazing of livestock or poultry

and for silviculture operations. Excluded from this definition are farm

residences, farm outbuildings and agrichemical facilities.

“Area Background” means CONCENTRATIONS OF REGULATED

SUBSTANCES THAT ARE CONSISTENTLY PRESENT IN THE

ENVIRONMENT IN THE VICINITY OF A SITE THAT ARE THE RESULT

OF NATURAL CONDITIONS OR HUMAN ACTIVITIES, AND NOT THE

RESULT SOLELY OF RELEASES AT THE SITE. (Section 58.2 of the Act)

“ASTM” means the American Society for Testing and Materials.

“Board” means the Illinois Pollution Control Board.

“Cancer Risk” means a unitless probability of an individual developing cancer

from a defined exposure rate and frequency.

“Cap” means a barrier designed to prevent the infiltration of precipitation or

other surface water, or impede the ingestion or inhalation of contaminants.

“Carcinogen” means A CONTAMINANT THAT IS CLASSIFIED AS A

CATEGORY A1 OR A2 CARCINOGEN BY THE AMERICAN

CONFERENCE OF GOVERNMENTAL INDUSTRIAL HYGIENISTS; A

CATEGORY 1 OR 2A/2B CARCINOGEN BY THE WORLD HEALTH

ORGANIZATION'S INTERNATIONAL AGENCY FOR RESEARCH ON

CANCER; A "HUMAN CARCINOGEN" OR "ANTICIPATED HUMAN

CARCINOGEN" BY THE UNITED STATES DEPARTMENT OF HEALTH

AND HUMAN SERVICE NATIONAL TOXICOLOGICAL PROGRAM; OR

A CATEGORY A OR B1/B2 CARCINOGEN BY THE UNITED STATES

ENVIRONMENTAL PROTECTION AGENCY IN the INTEGRATED RISK

INFORMATION SYSTEM OR A FINAL RULE ISSUED IN A FEDERAL

“Class I Groundwater” means groundwater that meets the Class I: Potable

Resource Groundwater criteria set forth in 35 Ill.inois Adm.inistrative Code

620.

“Class II Groundwater” means groundwater that meets the Class II: General

Resource Groundwater criteria set forth in 35 Ill.inois Adm.inistrative Code

620.

“Conservation Property” means any real property for which present or post-

remediation use is primarily for wildlife habitat.

“Construction Worker” means a person engaged on a temporary basis to

perform work involving invasive construction activities including, but not

limited to, personnel performing demolition, earth-moving, building, and

routine and emergency utility installation or repair activities.

“Contaminant of Concern” or “Regulated Substance of Concern” means ANY

CONTAMINANT THAT IS EXPECTED TO BE PRESENT AT THE SITE

BASED UPON PAST AND CURRENT LAND USES AND ASSOCIATED

RELEASES THAT ARE KNOWN TO THE person conducting a remediation

BASED UPON REASONABLE INQUIRY. (Section 58.2 of the Act)

“Engineered Barrier” means a barrier designed or verified using engineering

practices that limits exposure to or controls migration of the contaminants of

concern.

“Exposure Route” means the transport mechanism by which a contaminant of

concern reaches a receptor.

“Free Product” means a contaminant that is present as a non-aqueous phase

liquid for chemicals whose melting point is less than 30

C (e.g., liquid not

dissolved in water).

“GROUNDWATER” MEANS UNDERGROUND WATER WHICH OCCURS

WITHIN THE SATURATED ZONE AND GEOLOGIC MATERIALS

WHERE THE FLUID PRESSURE IN THE PORE SPACE IS EQUAL TO OR

GREATER THAN ATMOSPHERIC PRESSURE. (Section 3.64 of the Act)

“Groundwater Quality Standards” means the standards for groundwater as set

forth in 35 Ill.inois Adm.inistrative Code 620.

“Hazard Quotient” means the ratio of a single substance exposure level during a

specified time period to a reference dose for that substance derived from a

similar exposure period.

“Highway” means ANY PUBLIC WAY FOR VEHICULAR TRAVEL WHICH

HAS BEEN LAID OUT IN PURSUANCE OF ANY LAW OF THIS STATE,

OR OF THE TERRITORY OF ILLINOIS, OR WHICH HAS BEEN

ESTABLISHED BY DEDICATION, OR USED BY THE PUBLIC AS A

HIGHWAY FOR 15 YEARS, OR WHICH HAS BEEN OR MAY BE LAID

OUT AND CONNECT A SUBDIVISION OR PLATTED LAND WITH A

PUBLIC HIGHWAY AND WHICH HAS BEEN DEDICATED FOR THE

USE OF THE OWNERS OF THE LAND INCLUDED IN THE

SUBDIVISION OR PLATTED LAND WHERE THERE HAS BEEN AN

ACCEPTANCE AND USE UNDER SUCH DEDICATION BY SUCH

OWNERS, AND WHICH HAS NOT BEEN VACATED IN PURSUANCE OF

LAW. THE TERM “HIGHWAY” INCLUDES RIGHTS OF WAY,

BRIDGES, DRAINAGE STRUCTURES, SIGNS, GUARD RAILS,

PROTECTIVE STRUCTURES AND ALL OTHER STRUCTURES AND

APPURTENANCES NECESSARY OR CONVENIENT FOR VEHICULAR

TRAFFIC. A HIGHWAY IN A RURAL AREA MAY BE CALLED A

“ROAD”, WHILE A HIGHWAY IN A MUNICIPAL AREA MAY BE

CALLED A “STREET”. (Illinois Highway Code [605 ILCS 5/2-202])

“Highway Authority” means THE DEPARTMENT of Transportation WITH

RESPECT TO A STATE HIGHWAY; THE COUNTY BOARD WITH

RESPECT TO A COUNTY HIGHWAY OR A COUNTY UNIT DISTRICT

ROAD IF A DISCRETIONARY FUNCTION IS INVOLVED AND THE

COUNTY SUPERINTENDENT OF HIGHWAYS IF A MINISTERIAL

FUNCTION IS INVOLVED; THE HIGHWAY COMMISSIONER WITH

RESPECT TO A TOWNSHIP OR DISTRICT ROAD NOT IN A COUNTY

UNIT ROAD DISTRICT; OR THE CORPORATE AUTHORITIES OF A

MUNICIPALITY WITH RESPECT TO A MUNICIPAL STREET. (Illinois

Highway Code [605 ILCS 5/2-213])

“Human Exposure Pathway” means a physical condition which may allow for a

risk to human health based on the presence of all of the following:

contaminants of concern; an exposure route; and a receptor activity at the point

of exposure that could result in contaminant of concern intake.

“Industrial/Commercial Property” means any real property that does not meet

the definition of residential property, conservation property or agricultural

property.

“Infiltration” means the amount of water entering into the ground as a result of

precipitation.

“Institutional Control” means a legal mechanism for imposing a restriction on

land use, as described in Subpart J.

“Man-Made Pathways” means CONSTRUCTED physical conditions THAT

MAY ALLOW FOR THE TRANSPORT OF REGULATED SUBSTANCES

INCLUDING, BUT NOT LIMITED TO, SEWERS, UTILITY LINES,

UTILITY VAULTS, BUILDING FOUNDATIONS, BASEMENTS, CRAWL

SPACES, DRAINAGE DITCHES, OR PREVIOUSLY EXCAVATED AND

FILLED AREAS. (Section 58.2 of the Act)

“Natural Pathways” means NATURAL physical conditions that may allow FOR

THE TRANSPORT OF REGULATED SUBSTANCES INCLUDING, BUT

NOT LIMITED TO, SOIL, GROUNDWATER, SAND SEAMS AND

LENSES, AND GRAVEL SEAMS AND LENSES. (Section 58.2 of the Act)

“Negative Easement” means a right of the owner of the dominant or benefitted

estate or property to restrict the property rights of the owner of the servient or

burdened estate or property.

“Person” means an INDIVIDUAL, TRUST, FIRM, JOINT STOCK

COMPANY, JOINT VENTURE, CONSORTIUM, COMMERCIAL ENTITY,

CORPORATION (INCLUDING A GOVERNMENT CORPORATION),

PARTNERSHIP, ASSOCIATION, STATE, MUNICIPALITY,

COMMISSION, POLITICAL SUBDIVISION OF A STATE, OR ANY

INTERSTATE BODY INCLUDING THE UNITED STATES GOVERNMENT

AND EACH DEPARTMENT, AGENCY, AND INSTRUMENTALITY OF

THE UNITED STATES. (Section 58.2 of the Act)

“Point of Human Exposure” means the point(s) at which human exposure to a

contaminant of concern may reasonably be expected to occur. The point of

human exposure is at the source, unless an institutional control limiting human

exposure for the applicable exposure route has been or will be in place, in

which case the point of human exposure will be the boundary of the institutional

control. Point of human exposure may be at a different location than the point

of compliance.

“PQL” means Practical Quantitation Limit or estimated quantitation limit,

which is the lowest concentration that can be reliably measured within specified

limits of precision and accuracy for a specific laboratory analytical method

during routine laboratory operating conditions in accordance with "Test

Methods for Evaluating Solid Wastes, Physical/Chemical Methods", EPA

Publication No. SW-846, incorporated by reference in Section 742.210. When

applied to filtered water samples, PQL includes the method detection limit or

estimated detection limit in accordance with the applicable method revision in:

"Methods for the Determination of Organic Compounds in Drinking Water",

Supplement II", EPA Publication No. EPA/600/4-88/039; "Methods for the

Determination of Organic Compounds in Drinking Water, Supplement III",

EPA Publication No. EPA/600/R-95/131, all of which are incorporated by

reference in Section 742.210.

“RBCA” means Risk Based Corrective Action as defined in ASTM E-1739-95,

as incorporated by reference in Section 742.210.

“RCRA” means the Resource Conservation and Recovery Act of 1976 (42

U.S.C. 6921).

“Reference Concentration (RfC)” means an estimate of a daily exposure, in

units of milligrams of chemical per cubic meter of air (mg/m

), to the human

population (including sensitive subgroups) that is likely to be without

appreciable risk of deleterious effects during a portion of a lifetime (up to

approximately seven years, subchronic) or for a lifetime (chronic).

“Reference Dose (RfD)” means an estimate of a daily exposure, in units of

milligrams of chemical per kilogram of body weight per day (mg/kg/d), to the

human population (including sensitive subgroups) that is likely to be without

appreciable risk of deleterious effects during a portion of a lifetime (up to

approximately seven years, subchronic) or for a lifetime (chronic).

“Regulated Substance” means ANY HAZARDOUS SUBSTANCE AS

DEFINED UNDER SECTION 101(14) OF THE COMPREHENSIVE

ENVIRONMENTAL RESPONSE, COMPENSATION, AND LIABILITY

ACT OF 1980 (P.L. 96-510) AND PETROLEUM PRODUCTS INCLUDING

CRUDE OIL OR ANY FRACTION THEREOF, NATURAL GAS, NATURAL

GAS LIQUIDS, LIQUEFIED NATURAL GAS, OR SYNTHETIC GAS

USABLE FOR FUEL (OR MIXTURES OF NATURAL GAS AND SUCH

SYNTHETIC GAS). (Section 58.2 of the Act)

“Residential Property” MEANS ANY REAL PROPERTY THAT IS USED

FOR HABITATION BY INDIVIDUALS, OR where children have the

opportunity for exposure to contaminants through soil ingestion or inhalation at

educational facilities, health care facilities, child care facilities or outdoor

recreational areas.

“Restrictive Covenant or Deed Restriction” means a provision placed in a deed

limiting the use of the property and prohibiting certain uses. (Black's Law

Dictionary, 5th Edition)

“Right of Way” means THE LAND, OR INTEREST THEREIN, ACQUIRED

FOR OR DEVOTED TO A HIGHWAY. (Illinois Highway Code [605 ILCS

5/2-217])

“Similar-Acting Chemicals” are chemical substances that have toxic or harmful

effect on the same specific organ or organ system (see Appendix A.Tables E

and F for a list of similar-acting chemicals with noncarcinogenic and

carcinogenic effects).

“Site” means ANY SINGLE LOCATION, PLACE, TRACT OF LAND OR

PARCEL OF PROPERTY, OR PORTION THEREOF, INCLUDING

CONTIGUOUS PROPERTY SEPARATED BY A PUBLIC RIGHT-OF-WAY.

(Section 58.2 of the Act)

“Slurry Wall” means a man-made barrier made of geologic material which is

constructed to prevent or impede the movement of contamination into a certain

area.

“Soil Saturation Limit (C

sat

)” means the contaminant concentration at which soil

pore air and pore water are saturated with the chemical and the adsorptive limits

of the soil particles have been reached.

“Solubility” means a chemical specific maximum amount of solute that can

dissolve in a specific amount of solvent (groundwater) at a specific temperature.

“SPLP” means Synthetic Precipitation Leaching Procedure (Method 1312) as

published in “Test Methods for Evaluating Solid Waste, Physical/Chemical

Methods”, USEPA Publication No. SW-846, as incorporated by reference in

Section 742.210.

“SSL” means Soil Screening Levels as defined in USEPA's Soil Screening

Guidance: User's Guide and Technical Background Document, as incorporated

by reference in Section 742.210.

“Stratigraphic Unit” means a site-specific geologic unit of native deposited

material and/or bedrock of varying thickness (e.g., sand, gravel, silt, clay,

bedrock, etc.). A change in stratigraphic unit is recognized by a clearly distinct

contrast in geologic material or a change in physical features within a zone of

gradation. For the purposes of this Part, a change in stratigraphic unit is

identified by one or a combination of differences in physical features such as

texture, cementation, fabric, composition, density, and/or permeability of the

native material and/or bedrock.

“TCLP” means Toxicity Characteristic Leaching Procedure (Method 1311) as

published in "Test Methods for Evaluating Solid Waste, Physical/Chemical

Methods,", USEPA Publication No. SW-846, as incorporated by reference in

Section 742.210.

“Total Petroleum Hydrocarbon (TPH)” means the additive total of all petroleum

hydrocarbons found in an analytical sample.

“Volatile Organic Compounds (VOCs)” means organic chemical analytes

identified as volatiles as published in "Test Methods for Evaluating Solid Waste,

Physical/Chemical Methods,", USEPA Publication No. SW-846 (incorporated

by reference in Section 742.210), method numbers 8010, 8011, 8015, 8020,

8021, 8030, 8031, 8240, 8260, 8315, and 8316. For analytes not listed in any

category in those methods, those analytes which have a boiling point less than

200

C and a vapor pressure greater than 0.1 Torr (mm Hg) at 20

SOURCE: Amended at 21 Ill. Reg. ______________ , effective __________________.

SUBPART E: TIER I EVALUATION

Section 742.505

Tier 1 Soil and Groundwater Remediation Objectives

Soil

Inhalation Exposure Route

The Tier 1 soil remediation objectives for this exposure route

based upon residential property use are listed in Appendix B,

Table A.

The Tier 1 soil remediation objectives for this exposure route

based upon industrial/commercial property use are listed in

Appendix B, Table B. Soil remediation objective determinations

relying on this table require use of institutional controls in

accordance with Subpart J.

Ingestion Exposure Route

The Tier 1 soil remediation objectives for this exposure route

based upon residential property use are listed in Appendix B,

Table A.

The Tier 1 soil remediation objectives for this exposure route

based upon industrial/commercial property use are listed in

Appendix B, Table B. Soil remediation objective determinations

relying on this table require use of institutional controls in

accordance with Subpart J.

Soil Component of the Groundwater Ingestion Route

The Tier 1 soil remediation objectives for this exposure route

based upon residential property use are listed in Appendix B,

Table A.

The Tier 1 soil remediation objectives for this exposure route

based upon industrial/commercial property use are listed in

Appendix B, Table B.

The pH-dependent Tier 1 soil remediation objectives for

identified ionizable organics or inorganics for the soil component

of the groundwater ingestion exposure route (based on the total

amount of contaminants present in the soil sample results and

groundwater classification) are provided in Appendix B, Tables C

and D.

Values used to calculate the Tier 1 soil remediation objectives for

this exposure route are listed in Appendix B, Table F.

Evaluation of the dermal contact with soil exposure route is not required

under Tier 1.

Groundwater

The Tier 1 groundwater remediation objectives for the groundwater

component of the groundwater ingestion route are listed in Appendix B,

Table E.

The Tier 1 groundwater remediation objectives for this exposure route

are given for Class I and Class II groundwaters, respectively.

The evaluation of 35 Ill. Adm. Code 620.615 regarding mixtures of

similar-acting chemicals shall be considered satisfied for Class I

groundwater at the point of human exposure if: The Class I groundwater

remediation objectives set forth in Appendix B, Table E shall be

corrected for cumulative effect of mixtures of similar-acting

noncarcinogenic chemicals in accordance with the methodoligies set

forth in either subsection (b)(3)(A) or (B), if more than one chemical

listed in Appendix A, Table E is detected at a site and if such chemicals

affect the same target organ (i.e., has the same critical effect as defined

by the RfD)

No more than one similar-acting noncarcinogenic chemical as

listed in Appendix A, Table E is detected in the groundwater at

the site; and Calculate the weighted average using the following

equations:

ave =

CUO

where:

ave

= Weighted Average

through x

= Concentration of each individual contaminant at

the location of concern. Note that, depending on

the target organ/mode of action, the actual number

of contaminants will range from 2 to 14.

CUOx

= A Tier 1 remediation objective each x[a] from

Appendix B, Table E.

ii) If the value of the weighted average calculated in

accordance with the equations above is less than or equal

to 1.0, then the remediation objectives are met for those

chemicals.

ii) If the value of the weighted average calculated in

accordance with the equations above is greater than 1.0,

then additional remediation must be carried out until the

level of contaminants remaining in the remediated area

have a weighted average calculated in accordance with the

equation above less than or equal to one;

No carcinogenic contaminant of concern as listed in Appendix A,

Table H is detected in any groundwater sample associated with

the site, using analytical procedures capable of achieving either

the 1 in 1,000,000 cancer risk concentration or the ADL,

whichever is greater. Divide each individual chemical's

remediation objective by the number of chemicals in that specific

target organ group that were detected at the site. Each of the

contaminant concentrations at the site is then compared to the

remediation objectives that have been adjusted to account for this

potential additivity

If the conditions of subsection (b)(3) of this Section are not met, the

Class I groundwater remediation objectives set forth in Appendix B,

Table E shall be corrected for the cumulative effect of mixtures of

similar-acting chemicals using the following methodologies:

A) For noncarcinogenic chemicals, the methodologies set forth at

Section 742.805(c) or Section 742.915(h) shall be used; and

B) For carcinogenic chemicals, the methodologies set forth at

Section 742.805(d) or Section 742.915(h) shall be used.

SOURCE: Amended at 21 Ill. Reg. ______________ , effective __________________.

SUBPART H: TIER 2 GROUNDWATER EVALUATION

Section 742.805

Tier 2 Groundwater Remediation Objectives

To develop a groundwater remediation objective under this Section that exceeds

the applicable Tier 1 groundwater remediation objective, a person may request

approval from the Agency if the person has performed the following:

Identified the horizontal and vertical extent of groundwater for which the

Tier 2 groundwater remediation objective is sought;

Taken corrective action, to the maximum extent practicable to remove

any free product;

Using Equation R26 in accordance with Section 742.810, demonstrated

that the concentration of any contaminant of concern in groundwater will

meet:

The applicable Tier 1 groundwater remediation objective at the

point of human exposure; or

For any contaminant of concern for which there is no Tier 1

groundwater remediation objective, the Health Advisory

concentration determined according to the procedures specified in

35 Ill. Adm. Code 620, Subpart F at the point of human

exposure. A person may request the Agency to provide these

concentrations or may propose these concentrations under Subpart

I;.

Using Equation R26 in accordance with Section 742.810, demonstrated

that the concentration of any contaminant of concern in groundwater

within the minimum or designated maximum setback zone of an existing

potable water supply well will meet the applicable Tier 1 groundwater

remediation objective or if there is no Tier 1 groundwater remediation

objective, the Health Advisory concentration;

Using Equation R26 in accordance with Section 742.810, demonstrated

that the concentration of any contaminant of concern in groundwater

discharging into a surface water will meet the applicable water quality

standard under 35 Ill. Adm. Code 302;

Demonstrated that the source of the release is not located within the

minimum or designated maximum setback zone or within a regulated

recharge area of an existing potable water supply well; and

If the selected corrective action includes an engineered barrier as set

forth in Subpart K to minimize migration of contaminant of concern

from the soil to the groundwater, demonstrated that the engineered

barrier will remain in place for post-remediation land use through an

institutional control as set forth in Subpart J.

A groundwater remediation objective that exceeds the water solubility of that

chemical (refer to Appendix C, Table E for solubility values) is not allowed.

The contaminants of concern for which a Tier 1 remediation objective has been

developed shall be included in any mixture of similar-acting chemicals under

consideration in Tier 2. The evaluation of 35 Ill. Adm. Code 620.615

regarding mixtures of similar-acting chemicals shall be considered satisfied for

Class I groundwater at the point of human exposure if either of the following

requirements are achieved: Groundwater remediation objectives for chemicals

which affect the same target organ, organ system or similar mode of action shall

be met the requirements of Section 743.505(b)(3). Contaminants of concern for

which a Tier 1 remediation objective has been developed shall be included in

any mixture of similar-acting substances under consideration in Tier 2.

1) Calculate the weighted average using the following equations:

ave =

CUO

where:

ave

= Weighted Average

through x

= Concentration of each individual contaminant at

the location of concern. Note that, depending on

the target organ, the actual number of

contaminants will range from 2 to 14.

CUOx

= A Tier 1 or Tier 2 remediation objective must be

developed for each x

If the value of the weighted average calculated in

accordance with the equations above is less than or equal

to 1.0, then the remediation objectives are met for those

chemicals.

ii)

if the value of the weighted average calculated in

accordance with the equations above is greater than 1.0,

then additional remediation must be carried out until the

level of contaminants remaining in the remediated area

have a weighted average calculated in accordance with the

equation above less than or equal to one; or

2) Divide each individual chemical’s remediation objective by the number of

chemicals in that specific target organ group that were detected at the site.

Each of the contaminant concentrations at the site is then compared to the

remediation objectives that have been adjusted to account for this potential

additivity.

d) The evaluation of 35 Ill. Adm. Code 620.615 regarding mixtures of similar-

acting chemicals are considered satisfied if the cumulative risk from any

contaminant(s) of concern listed in Appendix A, Table H, plus any other

contaminant(s) of concern detected in groundwater and listed in Appendix A,

Table F as affecting the same target organ/organ system as the contaminant(s) of

concern detected from Appendix A, Table H, does not exceed 1 in 10,000.

SOURCE: Amended at 21 Ill. Reg. ______________ , effective __________________.

SUBPART I: TIER 3 EVALUATION

Section 742.915

Formal Risk Assessments

A comprehensive site-specific risk assessment shall demonstrate that contaminants of concern

at a site do not pose a significant risk to any human receptor. All site-specific risk assessments

shall be submitted to the Agency for review and approval. A submittal under this Section shall

address the following factors:

Whether the risk assessment procedure used is nationally recognized and

accepted including, but not limited to, those procedures incorporated by

reference in Section 742.210;

Whether the site-specific data reflect actual site conditions;

The adequacy of the investigation of present and post-remediation exposure

routes and risks to receptors identified at the site;

The appropriateness of the sampling and analysis;

The adequacy and appropriateness of toxicity information;

The extent of contamination;

Whether the calculations were accurately performed; and

Similar-acting chemicals shall be specifically addressed. At a minimum, the

chemicals subject to this requirement are identified in Appendix A, Tables E

and F; and

Proposals seeking to modify the target risk consistent with Section 742.900(d)

shall address the following factors:

the presence of sensitive populations;

the number of receptors potentially impacted;

the duration of risk at the differing target levels; and

the characteristic of the chemicals of concern.

SOURCE: Amended at 21 Ill. Reg. ______________ , effective __________________.

Section 742.APPENDIX A:

General

Section 742.TABLE E:

Similar-Acting Noncarcinogenic Chemicals with Noncarcinogenic

Toxic Effects on Specific Target Organs/Organ Systems or

Similar Modes of Action

Kidney

Acetone

Cadmium (Ingestion only)

Chlorobenzene

Dalapon

1,1-Dichloroethane

Di-n-octyl phthalate

Endosulfan

Ethylbenzene

Fluoranthene

Nitrobenzene

Pyrene

Toluene

2,4,5-Trichlorophenol

Vinyl acetate

Liver

Acenaphthene

Acetone

Butylbenzyl phthalate

Chlorobenzene

1,1-Dichloroethylene

Endrin

Ethylbenzene

Fluoranthene

Nitrobenzene

Picloram

Styrene

2,4,5-TP (Silvex)

Toluene

2,4,5-Trichlorophenol

Central Nervous System

Butanol

Cyanide (amenable)

2,4-Dimethylphenol

Endrin

Manganese

2-Methylphenol

Mercury

Styrene

Xylenes

Circulatory System

Antimony

Barium

2,4-D

cis-1,2-Dichloroethylene

Nitrobenzene

trans-1,2-Dichloroethylene

2,4-Dimethylphenol

Fluoranthene

Fluorene

Styrene

Zinc

Gastrointestinal System

Endothall

Hexachlorocyclopentadiene

Methyl bromide

Reproductive System

Barium

Boron

Carbon disulfide

2-Chlorophenol

1,2 Dibromo-3-Chloropropane (Inhalation

only)

Dinoseb

Methoxychlor

Phenol

Cholinesterase Inhibition

Aldicarb

Carbofuran

Decreased Body Weight Gains

and Circulatory System Effects

Atrazine

Simazine

Adrenal Gland

Nitrobenzene

1,2,4-Trichlorobenzene

Respiratory System

1,2-Dichloropropane

Hexachlorocyclopentadiene

Methyl bromide

Vinyl acetate

Immune System

2,4-Dichlorophenol

p-Chloroaniline

SOURCE: Amended at 21 Ill. Reg. ______________ , effective __________________.

Section 742.APPENDIX A: General

Section 742.TABLE F:

Similar-Acting Carcinogenic Chemicals With Carcinogenic Toxic

Effects on Specific Target Organs/Organ Systems or Similar

Modes of Action

Kidney

Bromodichloromethane

Chloroform

1,2-Dibromo-3-chloropropane

2,4-Dinitrotoluene

2,6-Dinitrotoluene

Hexachlorobenzene

Liver

Aldrin

Bis(2-chloroethyl)ether

Bis(2-ethylhexyl)phthalate

Carbazole

Carbon tetrachloride

Chlordane

Chloroform

DDD

DDE

DDT

1,2-Dibromo-3-chloropropane

1,2-Dibromoethane

3,3'-Dichlorobenzidine

1,2-Dichloroethane

1,3-Dichloropropane (Ingestion only)

1,3-Dichloropropylene

Dieldrin

2,4-Dinitrotoluene

2,6-Dinitrotoluene

Heptachlor

Heptachlor epoxide

Hexachlorobenzene

alpha-HCH

gamma-HCH (Lindane)

Methylene chloride

N-Nitrosodiphenylamine

N-Nitrosodi-n-propylamine

Pentachlorophenol

Tetrachloroethylene

Trichloroethylene

2,4,6-Trichlorophenol

Toxaphene

Vinyl chloride

Circulatory System

Benzene

2,4,6-Trichlorophenol

Gastrointestinal System

Benzo(a)anthracene

Benzo(b)fluoranthene

Benzo(k)fluoranthene

Benzo(a)pyrene

Chrysene

Dibenzo(a,h)anthracene

Indeno(1,2,3-c,d)pyrene

Bromodichloromethane

Bromoform

1,2-Dibromo-3-chloropropane

1,2-Dibromoethane

1,3-Dichloropropylene

Lung

Arsenic

Beryllium (Inhalation only)

Cadmium (Inhalation only)

Chromium, hexavalent (Inhalation only)

1,3-Dichloropropylene

Methylene chloride

N-Nitrosodi-n-propylamine

Vinyl chloride

Nasal Cavity

1,2-Dibromo-3-chloropropane

(Inhalation only)

1,2-Dibromoethane (Inhalation only)

N-Nitrosodi-n-propylamine

Bladder

3,3'-Dichlorobenzidine

1,3-Dichloropropylene

N-Nitrosodiphenylamine

SOURCE: Amended at 21 Ill. Reg. ______________ , effective __________________.

Section 742.APPENDIX A: General

TABLE H: Chemicals Whose Tier 1 Class I Groundwater Remediation Objective Exceeds

the 1 in 1,000,000 Cancer Risk Concentration.

Class I Groundwater 1 in 1,000,000 Cancer

Remediation Objective Risk Concentration ADL

Chemical (mg/l) (mg/l) (mg/l)

Aldrin 0.00004 0.000002 0.00004

Benzo(a)pyrene 0.0002 0.000005 0.00023

Bis(2-chloroethyl)ether 0.01 0.00003 0.01

Bis(2-ethylhexyl)phthalate 0.006 0.003 0.0027

Carbon Tetrachloride 0.005 0.0003 0.00003

Chlordane 0.002 0.00003 0.00014

Dibenzo(a,h)anthracene 0.0003 0.000005 0.0003

1,2-Dibromo-3-chloropropane 0.0002 0.00003 0.0002

1,2-Dibromoethane 0.00005 0.0000004 0.00005

3,3'-Dichlorobenzidine 0.02 0.00008 0.02

1,2-Dichloroethane 0.005 0.0004 0.00003

Dieldrin 0.00002 0.000002 0.00002

Heptachlor 0.0004 0.000008 0.00003

Heptachlor epoxide 0.0002 0.000004 0.00032

Hexachlorobenzene 0.00006 0.00002 0.00006

alpha-HCH 0.00003 0.000006 0.00003

Tetrachloroethylene 0.005 0.0007 0.00001

Toxaphene 0.003 0.00003 0.00086

Vinyl chloride 0.002 0.000015 0.00006

Ionizable Organics

N-Nitrosodiphenylamine 0.01 0.007 0.01

Nitrosodi-n-propylamine 0.01 0.000005 0.01

Pentachlorophenol 0.001 0.0003 0.001

2,4,6-Trichlorophenol 0.0064 0.003 0.0064

Inorganics

Arsenic 0.05 0.00002 0.001

Beryllium 0.004 0.0000083 0.004

SOURCE: Added at 21 Ill. Reg. ______________ , effective __________________.

IT IS SO ORDERED.

I, Dorothy M. Gunn, Clerk of the Illinois Pollution Control Board, hereby certify that

the above opinion and order was adopted on the 2nd day of October 1997, by a vote of 7-0.

Dorothy M. Gunn, Clerk

Illinois Pollution Control Board