1 

PROPOSED ADDITION OF A SUBSURFACE INTRUSION COMPONENT TO THE HAZARD

RANKING SYSTEM

Cross Index of Topics Covered in the Preamble, Proposed Rule and Technical Support Document

As of January 26, 2016

The following table is provided to serve as an aid for reviewing and providing comments on the proposed addition 

of a subsurface intrusion component to the Hazard Ranking System (HRS). The table is organized by key 

background, policy and technical topics associated with the proposed rule and the evaluation of sites using the 

proposed addition. The topics are referenced in the 2 main documents that support this proposed rule: the Federal 

Register Notice, which includes the preamble to the proposed rule and the proposed rule; and the Technical 

Support Document (TSD). Both documents are located in the docket for this proposed rule accessible electronically 

on Regulations.gov, docket number EPA-HQ-SFUND-2010-1086. EPA is seeking comments on the addition of the 

subsurface intrusion component to the HRS. Comments on unmodified parts of the HRS are not being requested 

and responses to such comments will not be provided if submitted. 

Topic Section(s)

BACKGROUND AND POLICY SECTIONS

The purpose for proposing a subsurface intrusion (SsI) 

component to the Hazard Ranking System (HRS)

Preamble: III.A

TSD: 1.3.a, 1.4

HRS purpose and the Superfund Site Assessment Process Preamble: IV.A

TSD: 2.1.a.i

Alternatives considered 

sites

for addressing subsurface intrusion Preamble: V.A.1, V.A.2

TSD: 2.1.b, 2.2.b, 3.2, 3.3

Approach for including a subsurface 

HRS

intrusion component in the Preamble: V.A

TSD: 2.1.c

Proposed HRS structure modification Preamble: V.B.2

TSD: 2.2.b.v, 2.2.c

Ground water intrusion Preamble: III.A

TSD: Appendix F

PROPOSED SSI RULE TECHNICAL SECTIONS (Non-radioactive substances)

Definitions Preamble: VI.B.1

Proposed Rule: 1.1

Terminology Updates Preamble: VII.B

Proposed Rule: 2.4.1.1

TSD: 9.0

Eligible Hazardous Substances Proposed Rule: 2.2.2, 5.2.0, 5.2.1.1.1, 5.2.1.1.2

TSD: 5.0, 6.1.b.i, 6.1.b.ii

Delineation of Areas of Subsurface Intrusion Preamble: VI.B.2

Proposed Rule: 5.2.0

TSD: 6.1.b.i, 6.1.b.ii, 6.3

Likelihood of Exposure Preamble: VI.B.2

Proposed Rule: 5.2.1.1

TSD: 4.0

Observed Exposure Preamble: VI.B.3.a
2 

Topic Section(s)

Proposed Rule: 5.2.1.1.1

TSD: 4.2

• Observed Exposure by Direct Observation Preamble: VI.B.3.a.i

Proposed Rule: 5.2.1.1.1

TSD: 4.2.a

• Observed Exposure by Chemical Analysis Preamble: VI.B.3.a.ii

Proposed Rule: 5.2.1.1.1

TSD: 4.2.b

• Ground water Intrusion Observed Exposure Preamble: VI.B.3.a.i, VI.B.5.a.i

Proposed Rule: 5.2.1.1.1

TSD: 4.3.d.v, Figure 6-2, Figure 6-9

Potential for Exposure Preamble: VI.B.3.b

Proposed Rule: 5.2.1.1.2

TSD: 4.3

• Structure Containment Preamble: VI.B.3.b.i

Proposed Rule: 5.2.1.1.2.1

TSD: 3.4, 4.3.c

• Route Characteristics Preamble: VI.B.3.b.ii

Proposed Rule: 5.2.1.1.2

TSD: 4.3.b, 4.3.d

• Depth to Contamination Preamble: VI.B.3.b.ii.a

Proposed Rule: 5.2.1.1.2.2

TSD: 3.4, 4.3.b, 4.3.d, 4.3.d.i

• Vertical Migration Preamble: VI.B.3.b.ii.b 

Proposed Rule: 5.2.1.1.2.3, 5.2.1.1.2.4

TSD: 3.4, 4.3.d, 4.3.d.ii

• Vapor Migration Potential Preamble: VI.B.3.b.ii.c

Proposed Rule: 5.2.1.1.2.4

TSD: 4.3.d, 4.3.d.iii

• Calculation of the Potential for Exposure Factor Value Preamble: VI.B.3.b.iii

Proposed Rule: 5.2.1.1.2.5

TSD: 4.3.d.vi

Waste Characteristics

Toxicity Preamble: VI.B.4.a

Proposed Rule: 5.2.1.2.1.1

TSD: 5.1.a

Degradation Preamble: VI.B.4.a

Proposed Rule: 5.2.1.2.1.2

TSD: 5.1.b

Hazardous Waste Quantity Preamble: VI.B.4.b

Proposed Rule: 5.2.1.2.2
3 

Topic Section(s)

TSD: 5.3, 5.3.a, 5.3.b, 5.3.c

Calculation of the Waste Characteristics Factor Category Value Preamble: VI.B.4.c

Proposed Rule: 5.2.1.2.3

TSD: 5.6

Targets

Delineation of Target Areas Preamble: VI.B.2, VI.B.5

Proposed Rule: 5.2.1.3

TSD: 6.1, 6.1.b.i, 6.1.b.ii

Eligible Targets Preamble: VI.B.5.a

Proposed Rule: 5.2.1.3

TSD: 6.2

Exposed Individual/Levels of Exposure Preamble: VI.B.5.b, VI.B.5.b.i, VI.B.5.b.ii

Proposed Rule: 5.2.1.3.1

TSD: 6.3.a

Evaluation of Populations within Target Areas Preamble: VI.B.5.c, VI.B.5.c.i, VI.B.5.c.ii

Proposed Rule: 5.2.1.3.2, 5.2.1.3.2.1, 

5.2.1.3.2.2, 5.2.1.3.2.3

TSD: 6.3.b, 6.3.b.i, 6.3.b.ii

Resources Preamble: VI.B.5.d

Proposed Rule: 5.2.1.3.3

TSD: 6.3.c

Calculation of SsI Component Score Preamble: VI.B.6.a

Proposed Rule: 5.2.2

Calculation of Site Score Preamble: VI.B.6.c

Proposed Rule: 2.1.1

PROPOSED SSI RULE TECHNICAL SECTIONS (Radioactive Substances)

Sites Containing Radioactive Substances Proposed Rule: 7.0

Likelihood of Exposure Proposed Rule: 7.1

• Observed Exposure Proposed Rule: 7.1.1

• Potential for Exposure Proposed Rule: 7.1.2

Waste Characteristics

• Degradation Proposed Rule: 7.2.3

TSD: 5.1.b

• Hazardous Waste Quantity Proposed Rule: 7.2.5.1, 7.2.5.2, 7.2.5.3

TSD: 5.3.d

Targets Proposed Rule: 7.3

TSD: 6.3.d

• Exposed Individual/Levels of Exposure Proposed Rule: 7.3.2

TSD: 6.3.d