1. DEPARTMENT OF ENVIRONMENTAL PROTECTION
      2. Bureau of Environmental Cleanup and Brownfields
      3. TABLE OF CONTENTS
      4. A. Introduction
      5. B. Definition and Use of Important Terms
      6. C. Overview of the VI Evaluation Process
      7. C.1. VI Conceptual Site Model
      8. C.2. Screening Values and Points of Application (POA)
      9. C.3. Guidelines for Evaluating VI Using a Combination of Standards
      10. D. Preferential Pathway Evaluation
      11. Figure 2. The Role of an External Preferential Pathway in the VI Evaluation
      12. E. Use of Proximity Distances
      13. Map View
      14. Side View
      15. F. Soil and Groundwater VI Screening
      16. F.1. Soil and Groundwater Screening Values
      17. F.2. Soil and Groundwater Screening Methods
      18. G. Alternative VI Assessment Options
      19. G.1. Soil Gas and Indoor Air Screening Values
      20. G.2. Using an OSHA Program to Address VI
      21. G.3. Soil Gas and Indoor Air Screening Methods
      22. G.4. Vapor Intrusion Modeling
      23. H. Mitigation and Environmental Covenants
      24. I. Remediating and Re-Assessing the VI Pathway
      25. J. Addressing Chapter 250 Requirements
      26. K. Evaluating the VI Pathway under the Site-Specific Standard
      27. K.1. Overview
      28. K.2. Preferential Pathway Evaluation
      29. K.3. Use of Proximity Distances
      30. K.4. Site-Specific Standard VI Screening
      31. Environmental Medium
      32. Attenuation Factor
      33. Residential
      34. Residential
      35. ConvertedResidential
      36. K.5. Performing a VI Risk Assessment and Modeling
      37. K.6. Mitigation and Remediation
      38. K.7. Addressing Chapter 250 Requirements
      39. Figure 5. Statewide Health Standard Vapor Intrusion Assessment Process
      40. Figure 6. Site-Specific Standard Vapor Intrusion Assessment Process
      41. Table 6. Collection of Data for Vapor Intrusion Screening
      42. Sample Conditions for VI Data Collection
      43. (Continued)
      44. L. References
  1. APPENDICES
      1. 1. Indoor Air
      2. Table X-1. Volatile Substances Without Inhalation Toxicity Data
      3. Table X-2. Inhalation Risk Variables
      4. 2. Sub-Slab Soil Gas
      5. 3. Near-Source Soil Gas
      6. 4. Soil
      7. Table X-3. Soil Partitioning Parameters
      8. 5. Groundwater
      9. 6. Attenuation Factor Summary
      10. Table X-4. Attenuation Factors
      11. Environmental
      12. Medium
      13. Table X-5. Vapor Intrusion Screening Value Calculation Parameters
      14. Appendix Y: Vapor Intrusion Modeling Guidance
      15. 1. Background
      16. 2. Assumptions
      17. 3. Statewide Health Standard Parameter Adjustments
      18. 4. Site-Specific Standard Parameter Adjustments
      19. 5. Petroleum Hydrocarbons
      20. 6. Attenuation Factor Risk Calculations
      21. 7. Report Contents
      22. Table Y-1. Adjustable J&E Model Input Parameters and Default Values
      23. Parameter Symbol SHS
      24. Residential Nonresidential
      25. Table Y-2. Guidance for the Selection of the J&E Model Soil Type
      26. Predominant Soil Types in Boring Logs Recommended Soil Classification
      27. Table Y-3. J&E Model Default Exposure Factors
      28. Figure Y-1. USDA SCS Soil Classification Chart
      29. Appendix Z: Vapor Intrusion Sampling Methods
      30. 1. Introduction
      31. a) Applicability
      32. b) Conceptual Site Model Development
      33. c) Spatial and Temporal Variability Considerations
      34. 2. Near-Source Soil Gas Sampling
      35. a) Description
      36. Table Z-1. Capillary Fringe Height Estimates
      37. Soil Type Lcz (cm) Lcz (ft)
      38. b) Sample Point Installation
      39. i) Installation of Temporary Points
      40. ii) Installation and Construction of Semi-Permanent Points
      41. 3. Sub-Slab Soil Gas Sampling
      42. a) Description
      43. b) Location
      44. c) Sample Point Installation
      45. 4. Indoor Air Sampling
      46. a) Sampling Indoor Air
      47. b) Outdoor Ambient Air Sampling
      48. 5. Sampling Soil Gas for Oxygen Content
      49. 6. Quality Assurance and Quality Control Procedures and Methods
      50. a) Sampling Procedures and Methods
      51. i) Pre-Sampling Survey
      52. ii) Sampling Equipment
      53. iii) Sampling Point Construction
      54. iv) Equilibration
      55. v) Leak Testing/Detection for Subsurface Sample Collection
      56. vi) Purging
      57. vii) Sampling Rates
      58. viii) Sample Recordation
      59. b) Data Quality Objective (DQO) Process, Sampling and Data Quality Assessment
      60. Process
      61. c) QA/QC Samples
      62. d) Analytical Methods
      63. e) Data Evaluation
      64. 7. Active Sub-Slab Depressurization System Testing
      65. a) Description
      66. b) Performance Testing Methods

261-0300-101 / DRAFT July 25, 2015 / Page i
DEPARTMENT OF ENVIRONMENTAL PROTECTION
Bureau of Environmental Cleanup and Brownfields
DOCUMENT NUMBER:
261-0300-101
TITLE:
Land Recycling Program Technical Guidance Manual for Vapor Intrusion
into Buildings from Groundwater and Soil under Act 2
EFFECTIVE DATE:
Upon publication of notice as final in the
Pennsylvania Bulletin
AUTHORITY:
The Land Recycling and Environmental Remediation Standards Act,
35 P.S. §§6026.101
et seq.
(Act 2) and the regulations issued pursuant to
that legislation at 25
Pa. Code
Chapter 250.
POLICY:
It is the policy of the Department of Environmental Protection
(Department or DEP) to implement Act 2 in accordance with the
regulations contained in Chapter 250 of the
Pa. Code
and as described in
this guidance manual.
PURPOSE:
DEP has developed a Technical Guidance Manual (TGM) to assist
remediators in satisfying the requirements of Act 2 and the regulations
published in Chapter 250 of the
Pa. Code
. This specific document
provides guidance for how to address vapor intrusion (VI) from
contaminated soil and groundwater into buildings. This document
replaces the
“Land Recycling Program Technical Guidance Manual –
Section IV.A.4. Vapor Intrusion into Buildings from Groundwater and Soil
under the Act 2 Statewide Health Standard”
dated January 24, 2004, in its
entirety.
APPLICABILITY:
The guidance is applicable to any person or persons conducting a site
remediation under Act 2.
DISCLAIMER:
The policies and procedures outlined in this guidance are intended to
supplement existing requirements. Nothing in the policies or procedures
shall affect regulatory requirements.
The policies and procedures herein are not an adjudication or a regulation.
There is no intent on the part of DEP to give the rules in these policies that
weight or deference. This document establishes the framework within
which DEP will exercise its administrative discretion in the future. DEP
reserves the discretion to deviate from this policy statement if
circumstances warrant.
PAGE LENGTH:
103 pages
DEFINITIONS:
Definitions of key terms are provided in the guidance
.
See 25
Pa. Code
Chapter 250 for additional definitions.

261-0300-101 / DRAFT July 25, 2015 / Page ii
TABLE OF CONTENTS
A.
Introduction......................................................................................................................................1
B.
Definition and Use of Important Terms...........................................................................................2
C.
Overview of the VI Evaluation Process...........................................................................................5
C.1.
VI Conceptual Site Model ...................................................................................................6
C.2.
Screening Values and Points of Application (POA)............................................................7
C.3.
Guidelines for Evaluating VI Using a Combination of Standards.....................................10
D.
Preferential Pathway Evaluation....................................................................................................10
E.
Use of Proximity Distances ...........................................................................................................13
F.
Soil and Groundwater VI Screening..............................................................................................17
F.1.
Soil and Groundwater Screening Values...........................................................................17
F.2.
Soil and Groundwater Screening Methods ........................................................................17
G.
Alternative VI Assessment Options...............................................................................................18
G.1.
Soil Gas and Indoor Air Screening Values........................................................................19
G.2.
Using an OSHA Program to Address VI...........................................................................19
G.3.
Soil Gas and Indoor Air Screening Methods.....................................................................20
G.4.
Vapor Intrusion Modeling..................................................................................................22
H.
Mitigation and Environmental Covenants .....................................................................................23
I.
Remediating and Re-Assessing the VI Pathway............................................................................25
J.
Addressing Chapter 250 Requirements .........................................................................................25
K.
Evaluating the VI Pathway under the Site-Specific Standard .......................................................26
K.1.
Overview............................................................................................................................26
K.2.
Preferential Pathway Evaluation........................................................................................27
K.3.
Use of Proximity Distances ...............................................................................................28
K.4.
Site-Specific Standard VI Screening .................................................................................28
K.5.
Performing a VI Risk Assessment and Modeling..............................................................29
K.6.
Mitigation and Remediation ..............................................................................................30
K.7.
Addressing Chapter 250 Requirements .............................................................................30
L.
References......................................................................................................................................57
APPENDICES ...........................................................................................................................................62
Appendix X: Methodology for Developing Statewide Health Standard Vapor Intrusion
Screening Values .......................................................................................................................................63
Appendix Y: Vapor Intrusion Modeling Guidance ..................................................................................75
Appendix Z: Vapor Intrusion Sampling Methods ....................................................................................85

261-0300-101 / DRAFT July 25, 2015 / Page iii
FIGURES
Figure 1. VI Screening Value Points of Application and Vertical Petroleum Product Proximity
Distances .....................................................................................................................................9
Figure 2. The Role of an External Preferential Pathway in the VI Evaluation.........................................12
Figure 3. The Use of Proximity Distances to Evaluate Potential VI Sources in Soil and
Groundwater..............................................................................................................................15
Figure 4. The Effect of Separate Phase Liquid on the Applicability of Screening Values.......................16
Figure 5. Statewide Health Standard Vapor Intrusion Assessment Process.............................................32
Figure 6. Site-Specific Standard Vapor Intrusion Assessment Process....................................................33
TABLES
Table 1. Groundwater Statewide Health Standard Vapor Intrusion Screening Values (SVGW).............34
Table 2. Soil Statewide Health Standard Vapor Intrusion Screening Values (SV
soil
) ..............................38
Table 3. Near-Source Soil Gas Statewide Health Standard Vapor Intrusion Screening Values
(SV
NS
)..........................................................................................................................................42
Table 4. Sub-Slab Soil Gas Statewide Health Standard Vapor Intrusion Screening Values (SV
SS
) ........46
Table 5. Indoor Air Statewide Health Standard Vapor Intrusion Screening Values (SV
IA
).....................50
Table 6. Collection of Data for Vapor Intrusion Screening......................................................................54
Table 7. Application of Statewide Health Standard Vapor Intrusion Screening Criteria.........................55

261-0300-101 / DRAFT July 25, 2015 / Page 1
A.
Introduction
Releases of volatile and some semi-volatile regulated substances to soil or groundwater can
result in intrusion of these regulated substances into indoor air. The resulting impacts to indoor
air may pose a threat to human health in existing or future inhabited buildings. For this exposure
pathway to exist there must be a source of volatile substances in the unsaturated zone soil or
groundwater at the water table, a current or future presence of inhabited buildings, and a
transport pathway along which vapors may migrate from the source into the inhabited
building(s). Inhabited buildings are buildings with enclosed air space that are designed for
human occupancy. In order to properly address this pathway the remediator first develops a
Conceptual Site Model (CSM) based on the site characterization to guide further assessment and,
if necessary, remediation.
This document provides guidance for addressing potential vapor intrusion (VI) of volatile
organic compounds (VOCs) and certain semi-volatile organic compounds (SVOCs) from soil
and/or groundwater sources including those impacted by separate phase liquid (SPL) into
inhabited buildings at sites using the Statewide health standard and the site-specific standard. As
such, this guidance establishes screening values and assessment options that can be used under
the Statewide health standard to address VI for existing or potential future inhabited buildings.
The potential VI impacts from volatile inorganic substances (e.g., mercury and cyanide) can only
be addressed using the site-specific standard or mitigation.
The VI screening value tables in
this guidance are not meant to evaluate VI under the site-specific standard.
Guidance on VI
evaluations under the site-specific standard, including the use of a human health inhalation risk
assessment, is provided in Section K.
Section 250.312 states that a Statewide health standard final report must include an assessment
of the VI exposure pathway. A site-specific standard exposure pathway assessment inclusive of
VI is required by Section 250.404, and risk assessments are performed pursuant to
Section 250.405. VI must be addressed for existing inhabited buildings and undeveloped areas
of the property where inhabited buildings could be constructed in the future. VI must also be
addressed at undeveloped properties where no current buildings exist but future inhabited
buildings could be constructed. A VI evaluation is not required for the background standard.
It is important to note that mitigation measures may be used for existing inhabited
buildings to eliminate unacceptable risks associated with VI under the Statewide health
and site-specific standards at any time in the evaluation process. If mitigation is used in
lieu of a detailed evaluation, an environmental covenant is needed to address VI concerns
with respect to existing or future inhabited buildings. As needed and appropriate, the
covenant would be designed to ensure: (i) that potential risks associated with VI will be
evaluated and addressed if or when an inhabited building is constructed in the future or
(ii) that appropriate mitigation measures will be taken, in lieu of a detailed evaluation in
buildings that exist or are constructed on the property.
If there is a petroleum release to surface or subsurface soil and a full site characterization
has not been performed, a remediator may attain the Statewide health standard by
following the requirements in Section 250.707(b)(1)(iii). Further VI analysis is not needed
in these situations for soil if the following conditions are also satisfied: (1) all requirements
of Section 250.707(b)(1)(iii) have been met; (2) at least one soil sample is collected on the
sidewall nearest the inhabited building unless there are substantially higher field

261-0300-101 / DRAFT July 25, 2015 / Page 2
instrument readings elsewhere; and (3) contamination has not contacted or penetrated the
building foundation based on observations of obvious contamination and the use of
appropriate field screening instruments. Evaluation of groundwater for VI potential may
still be necessary if groundwater contamination is identified as a potential VI concern.
This guidance should be used to evaluate VI for sites where the remedial investigation or
site characterization report is expected to be submitted following the effective date of this
guidance. If a site characterization report has been submitted and approved by the
Department prior to the effective date of this guidance, the remediator should update the
VI evaluation portion of the report only.
Beyond these actions, this guidance provides multiple options for addressing VI including soil
and groundwater screening values, alternative assessment options, mitigation with an
environmental covenant, and remediation. The alternative assessment options consist of
screening values for indoor air, sub-slab soil gas, and near-source soil gas in addition to VI
modeling. Use of the screening values and other options as well as important terms is described
below.
B.
Definition and Use of Important Terms
Several of the terms used in this guidance may have multiple meanings within the context of the
Land Recycling Program (LRP) or other DEP programs. Therefore, it is important that their
intended use in this guidance be well-defined. The following definitions and uses are provided
only for application under this VI guidance. They are presented in the order that allows the
reader to make the best sense of each definition as opposed to alphabetical order.
?
Hydrogeologic Zones:
o
Definition
- When used in this guidance, the following hydrogeologic terms are
related to one another as shown on Figure 1. In the
saturated zone
all
interconnected voids are filled with water. In practice, the top of the saturated
zone is identified as the
water table
, which is the water surface at atmospheric
pressure in appropriately constructed monitoring wells.
Groundwater
refers to
water in the saturated zone, below the water table. The
capillary fringe
is the
zone of tension saturation directly above the water table and its thickness is
dependent on the soil type in which it occurs. The base of the capillary fringe is
saturated, and soil pore space becomes progressively less filled with water upward
from the water table. In the
vadose zone
above the capillary fringe the pores are
not filled with water. The capillary fringe and the vadose zone are not readily
distinguished in the field. The
unsaturated zone
is defined here as the zone above
the water table, including both the capillary fringe and the vadose zone.
o
Use
- These terms are used to define points of application for various screening
values as shown on Figure and applicable sampling intervals for soil, groundwater
and near-source soil gas. They also pertain to the sources, fate, and transport of
vapors in the subsurface.

261-0300-101 / DRAFT July 25, 2015 / Page 3
?
Point of Application (POA):
o
Definition
- The locations in an inhabited building, the unsaturated zone, and the
saturated zone where screening values are applied to evaluate vapor intrusion.
o
Use
- POAs guide the selection of indoor air, sub-slab soil gas, near-source soil
gas, soil, and groundwater sampling locations. See Section C.2. The relationship
of the POAs to the building, the hydrogeologic zones, and the contamination are
displayed in Figure 1. Sampling guidance for each POA is provided in Table 6.
?
Acceptable Soil or Soil-like Material:
o
Definition
- Any unconsolidated material containing some amount of organic
material that occurs in the vadose zone above a potential vapor intrusion source
(soil and/or groundwater) that does not exceed the saturated hydraulic
conductivity of sand or the net air-filled porosity of silt at residual water content,
both as derived from Tables 5 and 3 in U.S. EPA (2004). Natural soils coarser
than sand or with air-filled porosity greater than silt may not constitute acceptable
soil (e.g., gravel). Conversely, fill material that is otherwise soil-like and does not
exceed the characteristics described above may constitute acceptable soil-like
material (e.g., mixtures of granular material comprised predominantly of sand, silt
and clay with brick, block and concrete fragments where the granular material
occupies virtually all of the interstitial space between the fragments).
o
Use
- A minimum of five feet of acceptable soil or soil-like material needs to be
present between a Potential VI Source and foundation level to permit the use of
groundwater screening values. The presence of acceptable soil or soil-like
material is also a condition for using vertical proximity distances and may exclude
a feature as a preferential pathway. Acceptable soil or soil-like material should
NOT exhibit any of the following characteristics:
1.
Obvious contamination (e.g., staining or odors)
2.
Readings from an appropriate field screening instrument in the jar head
space above soil samples that are greater than 100 ppmv
3.
Evidence of separate phase liquids (SPL)
4.
Exceedances of soil screening values.
Material that is suspected to be contaminated (via observation or from field
equipment readings) may be sampled to determine if the soil screening values are
exceeded. If screening values are not exceeded then that soil can be regarded as
an acceptable soil or soil-like material. Likewise, if evidence of SPL is found, the
SPL may be analyzed to confirm the presence of substances of VI concern. If
those substances are not detected then the soil can be considered to be acceptable
soil or soil-like material. Soil does not need to be sampled in areas beyond where
soil has been directly impacted by a release of regulated substances to
demonstrate an acceptable soil or soil-like material. For the purposes of the

261-0300-101 / DRAFT July 25, 2015 / Page 4
petroleum substance vertical proximity distances described below, the
Department further defines acceptable soil or soil-like material as exhibiting
greater than 2% oxygen in soil gas near the building slab.
?
Preferential Pathway:
o
Definition
- A natural or man‐made feature that acts as a conduit for vapor
transport by enhancing vapor migration from contaminated environmental media
through soil or soil‐like material to an existing or future inhabited building.
o
Use
- A feature must be proximal to both the contamination and a building and
have sufficient volume to be a preferential pathway. A suspected preferential
pathway should be investigated to determine if it results in an excess VI risk. The
presence of a preferential pathway may preclude the use of proximity distances or
soil and groundwater screening values. Utility lines and their foundation
penetrations in buildings the size of a typical single-family home are usually not
considered to be preferential pathways. Additional information regarding how to
identify and evaluate preferential pathways is provided in Section C and an
example is shown in Figure 2.
?
Proximity Distance:
o
Definition
- The distance, in the absence of a preferential pathway, between an
existing or future inhabited building and contaminated groundwater or soil, within
which VI could pose a risk.
o
Use
- The presence of separate phase liquid or exceedances of soil or groundwater
VI screening values within a proximity distance constitute a Potential VI Source.
For petroleum substances, the horizontal proximity distance is 30 feet. The
vertical proximity distance for petroleum hydrocarbons is six feet for adsorbed- or
dissolved-phase contamination and 15 feet for SPL. The use of the vertical
proximity distances requires the presence of acceptable soil or soil-like material.
The horizontal proximity distance for non-petroleum contamination is 100 feet.
There is no vertical proximity distance for non-petroleum contamination. Refer to
Section E for further guidance on proximity distances, and see Figure 3 for an
example.
?
Separate Phase Liquid:
o
Definition
- That component of a regulated substance present in some portion of
the void space in a contaminated environmental medium (i.e., soil or bedrock)
that is comprised of non-aqueous phase liquid (NAPL). As such, SPL is distinct
from the mass of a regulated substance in the contaminated environmental
medium that is adsorbed onto or diffused into the soil or rock matrix, or dissolved
in water or diffused into air that may also occupy a portion of that void space.
o
Use
- SPL within a proximity distance acts as a Potential VI Source, but it may be
analyzed to determine if it contains substances of VI concern. The presence of
SPL provides one basis for limiting the applicability of screening values and the

261-0300-101 / DRAFT July 25, 2015 / Page 5
modeling assessment option. As shown in Figure 4, the presence of a SPL layer
on the water table or SPL within a smear zone associated with such a layer
precludes the use of the groundwater screening values or the modeling assessment
option to evaluate groundwater contamination. This is the case whether the water
table occurs in the soil or bedrock beneath a site. These options are available,
however, beyond the limits of the SPL. In the unsaturated zone, soil
contamination that includes interstitial residual SPL precludes the use of soil
screening values and the modeling assessment option to evaluate soil
contamination since the model assumes partitioning from adsorbed mass on the
soil to pore water and then to soil gas, as opposed to direct evaporation from SPL
to soil gas. The same is true for screening values based on the generic soil-to-
groundwater MSCs since they also rely on this partitioning equation. However,
near-source soil gas screening values may be used provided the sampling is
performed above the SPL-impacted soil or groundwater (Figure 4). The soil gas
version of the Johnson and Ettinger (J&E) model (U.S. EPA, 2004) may also be
used to evaluate near-source soil gas sampling results under the modeling
assessment option.
?
Potential VI Source:
o
Definition
- Contamination under any of the following conditions constitutes a
Potential VI Source:
?
In unsaturated zone soil exceeding screening values within proximity
distances
?
In saturated zone groundwater exceeding screening values within
proximity distances
?
As separate phase liquid within proximity distances
?
Associated with a preferential pathway.
o
Use
- Identifies areas of a site where VI must be addressed through alternative
assessment options, remediation, mitigation, or restrictions established in an
environmental covenant. See Figures 2 and 3.
C.
Overview of the VI Evaluation Process
This guidance offers a flexible VI evaluation process for the Statewide health standard that
provides multiple alternatives to the remediator. Figure 5 presents a flowchart outlining the
process, which is described in detail in the following sections. It is important to note that the
purpose of Figure 5 is to illustrate how all of the steps in the VI evaluation process under the
Statewide health standard fit together. Figure 5 should not be used as the sole guide for
performing a VI evaluation; rather, it should be used in conjunction with the text of this
guidance. The principal steps of a VI evaluation under the Statewide health standard are:
?
Develop the CSM and assess preferential pathways;

261-0300-101 / DRAFT July 25, 2015 / Page 6
?
Identify Potential VI Sources from conditions that limit screening and/or exceedances of
soil and groundwater screening values within proximity distances;
?
Utilize alternative assessment options including screening near-source soil gas, sub-slab
soil gas, or indoor air data, or conducting VI modeling;
?
Mitigate buildings and ensure future protection with an environmental covenant;
?
Remediate the soil and/or groundwater contamination and reassess the pathway;
?
Address the Chapter 250 Statewide health standard requirements.
In most cases all of the above steps will not be necessary and the remediator is not required to
follow the process sequentially. For instance, buildings with a potentially complete VI pathway
may be mitigated without the collection of soil gas or indoor air data.
If conditions are identified that pose an immediate threat to human health or safety at any
time in the VI evaluation process, prompt interim actions should be taken to protect
human health.
C.1.
VI Conceptual Site Model
The VI CSM is central to the VI evaluation. The CSM is a representation of contaminant
sources, migration pathways, exposure mechanisms, and potential receptors. The CSM is
key to preparing a sampling plan (Appendix Z), and as the CSM is revised data gaps may
be identified that will guide further sampling. The CSM is also a prerequisite for VI
modeling (Appendix Y). The source description and contaminants of concern are
components of the CSM supported by soil, groundwater, and possibly near-source soil
gas data. The CSM development may also rely on sampling the vapor migration pathway
(sub-slab soil gas) or receptor exposures (indoor air).
The goal of the VI CSM is to describe how site characteristics, such as subsurface and
building conditions, might influence both the distribution of VOCs in soil gas and the
potential indoor air quality of structures in the vicinity of a soil or groundwater VOC
source. VOC concentrations in soil gas attenuate, or decrease, as the VOCs move from
the source through the soil and enter indoor air. The extent of attenuation is related to
site conditions, building properties and chemical properties. The soil vapor attenuation is
quantified in terms of an attenuation factor defined as the ratio of indoor air concentration
to source vapor concentration (Appendix X).
The level of the detail of the CSM should be tailored to the complexity of the site, the
available data and the selected Act 2 remedial standard. For the VI pathway, complex
relationships exist among the many factors that influence vapor intrusion. Hence,
multiple lines of evidence are often used to evaluate risks associated with the vapor
pathway. Finally, it should be remembered that the CSM is a dynamic tool to be updated
as new information becomes available during site characterization.

261-0300-101 / DRAFT July 25, 2015 / Page 7
Some important elements of the VI CSM include the following (California EPA, 2011a;
Massachusetts DEP, 2011; U.S. EPA, 2012a; Hawaii DoH, 2014):
?
Sources of contamination—origins, locations, substances, and concentrations;
presence of separate phase liquid
?
Transport mechanisms—route from source to indoor air, potential preferential
pathways
?
Subsurface and surface characteristics—soil type, depth to bedrock,
heterogeneities; ground cover
?
Groundwater and soil moisture—depth to water, water level changes, capillary
fringe thickness
?
Fate and transport—biodegradation of petroleum hydrocarbons
?
Weather—precipitation, barometric pressure changes, wind, frozen ground
?
Building construction—basement, slab on grade, or crawl space; foundation
condition (cracks, openings), sumps and French drains
?
Building heating and ventilation
?
Background sources—indoor air contaminants, ambient air pollution
?
Receptor types—residential, nonresidential, sensitive receptors; potential future
development.
C.2.
Screening Values and Points of Application (POA)
Screening values are published in Tables 1 through 5 for soil, groundwater, near-source
soil gas, sub-slab soil gas and indoor air. Separate screening values are provided in these
tables for residential and nonresidential uses of potentially affected inhabited buildings.
In addition, there are two distinct nonresidential building categories: ―nonresidential‖
and ―converted residential.‖ The first category refers to buildings constructed for
nonresidential use, and the second category refers to buildings that presently have a
purely nonresidential use although they were originally constructed for residential use.
An example is a dentist’s office in a converted home. The converted residential
screening values are based on vapor flow and air exchange rates representative of
residential structures but on exposure factors for nonresidential settings. Residential
screening values apply if a building has both residential and nonresidential uses
(e.g., apartments over a retail store).
The POA for each of these screening values is shown on Figure 1. Groundwater
screening values (SV
GW
) apply within the zone of groundwater saturation that will exhibit
concentrations of regulated substances representative of concentrations at the water table.
This is an interval within 10 feet or less of the water table. Soil screening values (SV
SOIL
)
apply throughout the volume of contaminated soil in the unsaturated zone. Near-source

261-0300-101 / DRAFT July 25, 2015 / Page 8
soil gas screening values (SV
NS
) apply just above an unsaturated zone soil VI source and
just above the capillary fringe for a groundwater VI source. Near-source soil gas
screening is also applicable to a preferential pathway when if it doesn’t penetrate the
building foundation. Sub-slab soil gas screening values (SV
SS
) apply immediately below
the slab of a building potentially impacted by VI, whether the building has a basement or
is slab-on-grade construction. Finally, indoor air screening values (SV
IA
) apply in the
lowest occupied space of a potentially impacted building.
Screening values cannot be calculated for substances that have no inhalation toxicity data
(Appendix X). Therefore, Statewide health standard VI evaluations are not required for
substances without screening values. However, the VI pathway would be satisfactorily
addressed if the concentrations for such substances were below practical quantitation
limits or if a mitigation system was installed. The remediator may also choose to
evaluate VI using the site-specific standard for chemicals without Chapter 250 inhalation
toxicity parameters.
Table 6 summarizes data collection conditions for VI screening and how to apply the
POAs. Methods for VI screening are described in Sections F and G and in Table 7.
Appendix X describes the methodology for developing the screening values.

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Figure 1. VI Screening Value Points of Application and Vertical Petroleum Product Proximity Distances

261-0300-101 / DRAFT July 25, 2015 / Page 10
C.3.
Guidelines for Evaluating VI Using a Combination of Standards
The VI pathway can be evaluated under the Statewide health standard, the site-specific
standard or a combination of both standards. When using a combination of standards the
VI pathway must be evaluated along with all of the other requirements of each standard
being used. The screening values presented in Tables 1 through 5 were designed to be
used only when attaining the Statewide health standard. However, under specific
circumstances, adjusted Statewide health standard VI screening values can be used when
evaluating VI under the site-specific standard. See Section K.4 for additional detail on
using screening values under the site-specific standard.
The VI pathway must be assessed to satisfactorily attain the Statewide health standard for
soil and groundwater. Under the Statewide health standard a remediator cannot evaluate
the VI pathway without also evaluating soil and groundwater because Act 2 does not
define indoor air or soil gas as environmental media. However, when using a
combination of standards a remediator can evaluate soil and groundwater under either the
Statewide health standard or the site-specific standard then separately evaluate VI
entirely under the site-specific standard. This is permissible because the site-specific
standard evaluates individual exposure pathways and Act 2 considers VI to be an
exposure pathway, not an environmental medium. Under the site-specific standard a risk
assessment is needed to evaluate the VI pathway if pathway elimination is not being
used. The Statewide health standard does not evaluate individual exposure pathways
separately, so regulators should not attempt to evaluate the VI pathway under the
Statewide health standard if soil and groundwater are being evaluated under the site-
specific standard. The remediator may also choose to evaluate VI for each substance and
medium using the process corresponding to the standard that it attains.
When using VI modeling under the Statewide health standard, the desired output is a
predicted indoor air concentration (Appendix Y). This modeled concentration should be
used in the evaluation of VI by comparing it to the associated indoor air screening value
or, under appropriate circumstances, occupational limits acceptable in conjunction with
an OSHA-compliant worker protection program (see Section G.2). The J&E model
(U.S. EPA, 2004) can calculate risk values which should not be used for Statewide health
standard evaluations. Use of risk calculations to evaluate VI is considered to be a risk
assessment, which is a tool to be used under the site-specific standard and is subject to
additional reporting requirements and fees. If calculated risk values are used in the VI
analysis, it will be assumed that the site is being remediated under a combination of
standards and all associated fees and requirements of both standards will apply.
If the remediator intends to use the site-specific standard as the sole means of evaluating
VI or under a combination of standards, the site-specific standard VI process described in
Section K should be used.
D.
Preferential Pathway Evaluation
Preferential pathways can act as conduits for contaminated vapors to flow from areas of
contamination into inhabited buildings (see definition in Section B and Figure 2). The presence
and significance of preferential pathways are identified during CSM development. Some

261-0300-101 / DRAFT July 25, 2015 / Page 11
examples of preferential pathways include sewer lines with faulty traps, utility line trenches
backfilled with gravel, basement sumps, and bedrock fractures.
Utility lines and their foundation penetrations in buildings the size of a typical single-family
home are usually not considered to be preferential pathways. The backfill material around utility
lines is often what acts as the conduit for vapor transport, not the utility line itself. Since most
excavations at structures the size of a typical single-family home are backfilled with native soil,
these features do not act as preferential pathways. Underground features associated with larger
buildings are typically backfilled with non-native soil (e.g. gravel or stone), which can act as a
conduit for vapors and should therefore be considered potential preferential pathways.
Remediators should take reasonable measures to identify and assess potential preferential
pathways. This should include a careful visual inspection of the property and nearby streets and
sidewalks for signs of underground utility lines and vaults, an examination of the building
interior for utility penetrations, sumps, and overall foundation condition, and a Pennsylvania One
Call notification. It may be appropriate to review building plans, contact utilities, or conduct
instrumental surveys (such as ground-penetrating radar). The Department does not require
remediators to prove the absence of preferential pathways.
If a potential preferential pathway is
external
to a building (i.e. the feature extends beyond the
building footprint), such as a utility trench, a sewer line, or bedrock fractures, the proximity
distances to a source area, as described in Section E, should not be used because these distances
are based on the movement of vapors, and associated attenuation, through soil. Therefore, an
area of contamination that exceeds screening values beyond a proximity distance from a building
may be a Potential VI Source (Figure 2). For a subsurface feature that is external to a building
the following conditions cause it to be regarded as a preferential pathway:
?
Soil or groundwater contamination exceeding VI screening values within 30 horizontal
and five vertical feet of the feature, or SPL is present within 30 horizontal and
15 vertical feet of the feature; AND
?
The feature passes within five horizontal and five vertical feet of the building
foundation.
To be excluded as a preferential pathway, soil within the distances specified above around the
subsurface feature and the building foundation should consist of acceptable soil or soil-like
material. (For SPL a minimum of five vertical feet of acceptable soil or soil-like material should
be present.) As an example, if a high-permeability backfilled trench passes through soil
contamination that exceeds screening values, and six feet of acceptable soil or soil-like material
is present between the trench and the building foundation, then no further VI analysis would be
necessary.

261-0300-101 / DRAFT July 25, 2015 / Page 12
Figure 2. The Role of an External Preferential Pathway in the VI Evaluation
Figure 2 illustrates the evaluation of a potential external preferential pathway. In the map view,
Zone A is the area of contamination identified in the site characterization. Zones B and C exceed
the soil and/or groundwater screening values, but it is beyond the horizontal proximity distance
from the building. Zone C is the area of exceedences within 30 feet horizontally from the feature
that is a potential preferential pathway. The side view shows that some of the contamination is
above the water table and some is below. As groundwater is greater than five feet below the
feature, the groundwater contamination in Zone D is not of concern for the potential preferential
pathway. Zone E, in unsaturated soil, is within 30 feet horizontally and five feet vertically of the
feature. Furthermore, the feature is separated by less than five feet from the building foundation.
This evaluation demonstrates that the feature is a preferential pathway and Zone E is a Potential
VI Source; therefore, further VI assessment is required.
The Department recommends a progressive approach to evaluating external preferential
pathways. The investigation can begin in the vicinity of the source, for instance by sampling soil
gas in between the area of screening value exceedences and the preferential pathway, or by
collecting vapor samples within the preferential pathway itself. As a next step soil gas sampling
could be performed in the vicinity of the nearest potential receptor along the preferential pathway
if it does not penetrate the building. If necessary, indoor air sampling should be conducted. If
there are no screening values exceedences or excessive risks at the first potential receptor, then
>5 ft
Potential
VI Source
Map View
Side View
saturated
zone
<5 ft
E
inhabited
building
horizontal
proximity
distance
preferential
pathway
30 ft
<5 ft
contamination
A
exceeds SVs
B
C
D

261-0300-101 / DRAFT July 25, 2015 / Page 13
the remediator is generally not expected to investigate the next potential receptor(s) near the
preferential pathway.
If a potential preferential pathway is completely
internal
to a building’s structure, such as a
sump, a French drain, or a dirt basement floor, then only the horizontal proximity distances
discussed in Section D are applicable. The vertical proximity distances and the distances given
above for external subsurface features are based on attenuation through soil and therefore do not
apply to potential preferential pathways that are entirely inside a building. Sumps and French
drains should be evaluated for both wet and dry conditions. Wet sumps may introduce
contaminated groundwater into the building. Dry sumps may convey contaminant vapors
directly through the foundation.
If preferential pathways are identified, the remediator should not use soil or groundwater
screening values because they are based on the attenuation of vapors through acceptable soil-like
material and an intact foundation slab which may not occur in the presence of a preferential
pathway. Similarly, the default model for predicting indoor air concentrations (see Appendix Y)
using soil or groundwater data should not be used when preferential pathways are present
because this model is also based on the attenuation of soil vapors through soil and an intact slab.
Near-source soil gas and sub-slab soil gas screening should not be performed if the preferential
pathway penetrates the building foundation. (However, if it is an internal preferential pathway,
then this data may be screened with indoor air screening values.) The remediator may model
appropriately collected near-source soil gas data if the preferential pathway does not penetrate
the building foundation.
As described later in this guidance, a preferential pathway may be eliminated by appropriate site
remediation or mitigation actions.
E.
Use of Proximity Distances
If there are no preferential pathways, then the remediator may use horizontal and vertical
proximity distances from existing or future inhabited buildings to identify Potential VI Sources
(Figure 5). To accomplish this step, existing and/or future inhabited buildings are located and
proximity distances from each of these buildings are delineated. Then, relying on the results of
site characterization and/or post-remediation sampling, any areas of contaminated groundwater
at the water table and volumes of contaminated unsaturated zone soil that exceed applicable
screening values within a proximity distance from an existing or future inhabited building are
identified (Figure 3). Areas of SPL and areas predicted to exceed the screening values in a fate-
and-transport analysis are identified. If no SPL or soil or groundwater exceedances are present
within these proximity distances then additional VI analysis is unnecessary.
If there is contamination both within a proximity distance (e.g., Figure 3) and near a potential
preferential pathway (e.g., Figure 2), then the remediator evaluates each area of contamination
separately. There may be Potential VI Sources in both locations. The process outlined in
Figure 5 would be repeated for each area of contamination and each potential vapor migration
route.
A proximity distance is the distance between an existing or future inhabited building and
contaminated groundwater or soil within which VI could pose a risk. Proximity distances are a
function of the mobility and persistence of the chemical, as well as, in the case of petroleum

261-0300-101 / DRAFT July 25, 2015 / Page 14
substances, the depth of the source and the characteristics of the subsurface materials. There are
distinct proximity distances for petroleum and non-petroleum regulated substances:
?
For contamination associated with non-petroleum substances present in soil and/or
groundwater, a horizontal proximity distance of 100 feet applies between the building
and SPL or soil or groundwater screening value exceedances; and
?
For soil and/or groundwater contamination associated with petroleum substances and
related hydrocarbons, a horizontal proximity distance of 30 feet and a vertical proximity
distance of six feet apply between the building and soil or groundwater screening value
exceedances. For petroleum SPL, a further vertical proximity distance of 15 feet applies
between the SPL and foundation level.
Note: The petroleum proximity distances apply to any petroleum substance, not just the
substances listed on the Petroleum Short List from the Land Recycling Program Technical
Guidance Manual.
Petroleum substances are treated differently than non-petroleum substances in setting proximity
distances because their high rates of biodegradation play a key role in diminishing the effects of
VI (U.S. EPA, 2013a; ITRC, 2014). Petroleum hydrocarbons typically biodegrade under both
anaerobic and aerobic conditions, with aerobic degradation occurring much more rapidly. Since
soil oxygen content is generally higher in surface and shallow sub-surface soils, vapors from
petroleum hydrocarbons biodegrade rapidly as they migrate upward through the soil column
reducing their concentrations prior to migrating into inhabited buildings. The Department
defines an acceptable soil or soil-like material as having greater than 2% oxygen for purposes of
applying proximity distances for petroleum substances. Measurement of soil oxygen content is
not required unless there is reason to believe the soil is anaerobic (see Appendix Z for a
recommended methodology).
If only petroleum substances have been detected the remediator determines the horizontal and
vertical distance of the building foundation to the groundwater plume or soil contamination. If a
current or future inhabited building is greater than or equal to 30 horizontal feet from an area of
petroleum substance SPL or screening value exceedances, then there is adequate distance for
aerobic biodegradation to occur to reduce the vapor concentrations to acceptable levels.
Likewise, if there is greater than or equal to six feet of acceptable soil or soil-like material
vertically between the bottom of a current and/or future inhabited building foundation and the
top of the dissolved phase groundwater or unsaturated zone soil petroleum screening value
exceedances, then there is adequate distance for biodegradation to occur to reduce the vapor
concentrations to acceptable levels. The minimum vertical separation distance is 15 feet for
petroleum SPL, at least six feet of which should be acceptable soil or soil-like material. Vertical
distances are calculated using the maximum groundwater elevation and the top of the measured
or inferred SPL (smear zone or residual LNAPL). If neither the horizontal nor vertical proximity
condition is met, the remediator must evaluate VI.

261-0300-101 / DRAFT July 25, 2015 / Page 15
Figure 3. The Use of Proximity Distances to Evaluate
Potential VI Sources in Soil and Groundwater
An example of the application of proximity distances is shown in Figure 3. In the map view,
Zone A is the area of contamination identified in the site characterization. Zones B and C exceed
the soil and/or groundwater screening values. Zone C is the area within the horizontal proximity
distance from the existing building. As illustrated in the side view, some of the contamination is
above the water table and some is below. Zones D and E, in groundwater, are below the vertical
proximity distance for petroleum substances. Zone F, in unsaturated zone soil, is not, but it is
entirely beyond the horizontal proximity distance from the building. Therefore, if the
contamination consists only of petroleum hydrocarbons, then there is no Potential VI Source and
no further VI evaluation would be required for the currently occupied building. If the
contamination consists of non-petroleum substances, then Zones C and E are a Potential VI
Source requiring additional assessment.
inhabited
building
horizontal
proximity
distance
vertical
proximity
distance
contamination
A
exceeds SVs
Potential VI Source
B
C
Map View
Side View
saturated
zone
F
D
G
E

261-0300-101 / DRAFT July 25, 2015 / Page 16
Figure 4. The Effect of Separate Phase Liquid on the Applicability of Screening Values

261-0300-101 / DRAFT July 25, 2015 / Page 17
F.
Soil and Groundwater VI Screening
F.1.
Soil and Groundwater Screening Values
There are two sets of groundwater VI screening values: 1) at depths less than five feet
below the building foundation it is the Act 2 groundwater MSCs, and 2) at depths greater
than or equal to five feet below the foundation it is the values provided in Table 1. The
soil VI screening values are provided in Table 2. The derivation of these values is
explained in Appendix X. Table 6 describes important conditions for collecting soil and
groundwater data that will be used for VI screening.
The groundwater VI screening values (SV
GW
) for depths less than five feet below
foundation level are the used aquifer groundwater MSCs (Chapter 250, Appendix A,
Table 1). The groundwater screening values for depths greater than or equal to five feet
below foundation level are the higher of the groundwater MSCs and the calculated
groundwater screening values based on EPA’s empirical attenuation factors. The
groundwater MSCs are considered suitable VI screening values because groundwater
with concentrations at or below the MSCs is acceptable for use inside buildings (e.g.
cooking, showering, cleaning, etc.).
The soil VI screening values (SV
SOIL
) are the higher of the generic soil-to-groundwater
numeric values (Chapter 250, Appendix A, Table 3B) and calculated soil screening
values. Soil screening values may be applied at any depth below a building foundation.
The calculated soil screening values are established using the acceptable risk-based
indoor air concentrations and model-derived attenuation factors. The generic soil-to-
groundwater numeric values are considered appropriate for VI screening because soil
contamination that is unable to impact aquifers in excess of groundwater MSCs is also
unlikely to pose an excess inhalation risk. Furthermore, VI sources associated with
contaminated soil are typically not directly beneath buildings and they do not have an
infinite lateral extent, making the assumptions of the model for calculating soil screening
values conservative.
F.2.
Soil and Groundwater Screening Methods
As shown in Figure 5, screening values for soil and groundwater may be used to address
VI provided that no preferential pathway is present and there is no SPL within the
appropriate horizontal proximity distance. The remainder of this subsection assumes that
neither of these conditions exists to limit the use of soil and groundwater screening
values.
For purposes of screening soil and groundwater data to evaluate the vapor intrusion
pathway using one or a combination of remediation standards, the concentration of a
regulated substance is not required to be less than the limits relating to the PQLs for a
regulated substance in accordance with Section 250.4 (Section 250.701(c)).
Vapor intrusion can be addressed by screening either characterization data or post-
remediation data for soil and groundwater. The soil and groundwater sampling results
combined with applicable proximity distances are used in the screening analysis to
determine if any Potential VI Sources are present (see Figure 3). Important conditions

261-0300-101 / DRAFT July 25, 2015 / Page 18
for screening are listed in Table 6. Among these are that groundwater must be sampled at
the water table because it will be the source of vapors that can migrate to buildings.
Proper characterization of soil and groundwater contamination is required at all Act 2
sites and this data alone may be sufficient for the VI assessment. If the site attains the
Statewide health standard on the basis of soil and groundwater characterization data
without remediation being performed, then that data may be used for VI screening
(Table 7). No further VI evaluation is necessary if the applicable characterization data
does not exceed soil and groundwater VI screening values (SV
SOIL
, SV
GW
). If the
characterization data exceed MSCs but the remediator intends to pursue the Statewide
health standard (i.e., by means of remediation), then the characterization data should be
used to identify Potential VI Sources. If there are none, then no further VI evaluation is
necessary.
When a Potential VI Source is remediated, VI screening may be performed with the soil
or groundwater attainment data in accordance with the sampling methodologies and
related statistical tests of Chapter 250, Subchapter G (Table 7). For example, when at
least eight consecutive quarters of groundwater attainment data have been collected, the
remediator may apply the 75%/10x rule to monitoring wells on the property or the
75%/2x rule for off-site monitoring wells for VI screening (Section 250.707(b)(2)(i)).
Fewer than eight rounds of data may be screened with Department approval pursuant to
Section 250.704(d).
For soil remediated
in situ
, the POA is throughout the volume of soil originally
determined to exceed the soil screening value(s) (i.e., the Potential VI Source). For soil
excavated and removed from the site, the POA is the margins of the excavation.
The number and locations of groundwater monitoring wells is selected on the basis of
their representativeness with respect to water quality in the relevant portion of the plume.
For groundwater on developed properties, the POA is throughout the area of a plume that
has been identified as a Potential VI Source prior to VI assessment or remediation. For
groundwater on undeveloped properties or in undeveloped portions of properties where
future inhabited buildings may be constructed, the POA is throughout the area of a plume
that has been identified as a Potential VI Source prior to VI assessment or remediation
and is not within an area subject to an environmental covenant restricting construction of
future inhabited buildings.
G.
Alternative VI Assessment Options
The purpose of the VI assessment options is to gather and evaluate enough information to
adequately address the VI pathway for groundwater and/or soil under the Statewide health
standard. These options may be applied to Potential VI Sources. There are several assessment
options the remediator may choose:
?
Near-source soil gas concentrations < SV
NS
(Not available if a preferential pathway
penetrates the building foundation or a Potential VI Source is less than five feet below
foundation level.)
OR Near-source soil gas concentrations < SV
SS
(Available for a
Potential VI Source less than five feet below foundation level, but not if it is less than
five feet below grade or if a preferential pathway penetrates the foundation.)

261-0300-101 / DRAFT July 25, 2015 / Page 19
?
Sub-slab soil gas concentrations < SV
SS
for existing buildings
(Not available if a
preferential pathway penetrates the building foundation.)
?
Indoor air concentrations < SV
IA
at existing buildings
?
Vapor intrusion modeling using acceptable input parameters
(Not available for soil
or groundwater where a preferential pathway or SPL is present. Not available for near-
source soil gas if a preferential pathway penetrates the foundation.)
G.1.
Soil Gas and Indoor Air Screening Values
The near-source soil gas screening values (SV
NS
) are provided in Table 3, the sub-slab
soil gas screening values (SV
SS
) in Table 4, and the indoor air screening values (SV
IA
) in
Table 5. The derivation of these values is explained in Appendix X. Table 6 describes
important conditions for collecting soil gas and indoor air data to be used for VI
screening. Detailed information on sampling methodologies is provided in Appendix Z.
The near-source soil gas screening values are based on attenuation factors derived from
modeling and endpoint concentrations equal to the acceptable indoor air screening values.
Near-source soil gas is measured within or directly above an unsaturated zone soil source
or directly above the capillary fringe for a groundwater source. Near-source soil gas may
also be sampled immediately above a preferential pathway that does not penetrate the
building foundation. Vapor concentrations measured in near-source soil gas are
theoretically the highest possible concentrations because they are directly adjacent to the
source.
The sub-slab soil gas screening values are based on EPA’s empirical attenuation factors
and endpoint concentrations equal to the acceptable indoor air screening values. Sub-slab
samples are collected immediately below the foundation, and their proximity to the
receptor makes them a reliable indicator of potential exposures. Sub-slab sampling may
also be done beneath intact paved areas large enough to be representative of future
inhabited buildings without basements.
The indoor air screening values (SV
IA
) are calculated using the inhalation risk equations
in EPA’s risk assessment guidance. Indoor air data represent conditions that are as close
to the receptor as possible and, therefore, provide the most accurate representation of
concentrations at the point of exposure. Indoor air can be influenced by other vapor
sources inside or outside of the structure. Other vapor sources can falsely be attributed to
indoor air contamination caused by a release being evaluated; however, the possibility of
not detecting vapor concentrations that are present in indoor air is very low. If the
remediator suspects that other sources of vapor contamination could be a problem at their
site, indoor air sampling is not recommended.
G.2.
Using an OSHA Program to Address VI
The indoor air screening values are based on the same target risk (i.e., hazard quotient
(HQ) = 1.0 and excess cancer risk level = 10
-5
) used for the soil and groundwater
medium-specific concentrations (MSCs) published in Chapter 250 for attainment of the

261-0300-101 / DRAFT July 25, 2015 / Page 20
Statewide health standard. However, a special case exists when VI from soil or
groundwater into industrial (or commercial) facilities that use the same chemical(s) in
their industrial processes makes VI from environmental sources difficult to evaluate.
DEP does not regulate indoor air. Rather, worker exposure to chemical vapors associated
with an onsite industrial process is regulated by the Occupational Safety and Health
Administration (OSHA). It is nearly impossible to accurately isolate and measure the VI
component of the indoor air that can be attributed to soil and groundwater contamination
using indoor air sampling. As a result, workers who are not properly trained to work in
areas that contain these vapors can still be exposed to soil or groundwater related vapors
due to VI.
Therefore, an OSHA program can be used to address VI if the remediator can
demonstrate that the substances in the soil or groundwater contamination they are
evaluating are currently being used in a regulated industrial process inside the inhabited
building(s) and that OSHA regulations are fully implemented and documented in all areas
of the building(s). This means that workers and others who might be exposed to all
chemicals of concern have full knowledge of the chemicals’ presence, have received
appropriate health and safety training, and have been provided with the appropriate
protective equipment (when needed) to minimize exposure. It is the expectation that
MSDS sheets are posted, a hazard communications plan is in place, and employees have
been properly trained in the handling of chemicals and the use of personal protective
equipment. It is also expected that a quantitative analysis of indoor air data using
occupational screening values will be included in the VI assessment. If OSHA
implementation cannot be documented, then an OSHA program cannot be used as a
means of addressing VI.
Facilities that use an OSHA program to address VI from soil or groundwater
contamination that is not otherwise evaluated under this section will need an
environmental covenant to ensure that future owners know that the previous owner relied
on the OSHA program to protect its workers. If the future owner does not use the same
chemical(s) in their industrial process and/or does not fully implement an OSHA program
for the same chemical(s), then VI would need to be evaluated.
G.3.
Soil Gas and Indoor Air Screening Methods
Near-source soil gas, sub-slab soil gas, and indoor air data may be acquired during the
characterization phase or following soil or groundwater remediation. Vapor intrusion
sampling requirements and statistical tests are not specified in Chapter 250. Therefore,
the number of sample points for addressing VI is determined based on the CSM,
professional judgment, and the guidance in this document. DEP recommends a minimum
of two sample locations per building for near-source soil gas, sub-slab soil gas, and
indoor air sampling.
The characterization data and CSM are used to determine the size and location of the area
of Potential VI Sources. For most sites, sampling should be biased toward the most
contaminated areas or the most appropriate locations for the sample type. When a large
number of samples is necessary, the sample locations should be determined by an
appropriate randomization method (e.g., systematic random sampling, stratified random
sampling, etc.) as described in the RCRA SW-846 manual (U.S. EPA, 2007, Chapter 9).

261-0300-101 / DRAFT July 25, 2015 / Page 21
These decisions are made on a case-by-case basis. Other important conditions for
collecting data for the VI evaluation are listed in Table 6 and Appendix Z.
The POA for near-source soil gas is at least five feet below grade (Figure 1). If near-
source soil gas samples are collected at least five feet below foundation level, then the
data may be screened using near-source soil gas screening values (SV
NS
). If near-source
soil gas samples are collected less than five feet below foundation level, then the data
may be screened using sub-slab soil gas screening values (SV
SS
). Acceptable soil or soil-
like material should be present between the sampling depth and the building foundation.
For near-source soil gas above a groundwater source, the number and locations of soil
gas vapor probes are selected on the basis of their representativeness with respect to
water quality in the relevant portion of the plume. When the water table occurs in soil,
the POA for near-source soil gas is nominally within one foot of the top of the capillary
fringe, or as close to this interval as sampling can reasonably be performed given typical
fluctuations in groundwater levels. Theoretical capillary fringe thicknesses for different
soil types are provided in Table 10 of U.S. EPA (2004). When the water table occurs
within bedrock, the POA for near-source soil gas is within one foot of the soil-bedrock
interface.
Sub-slab and indoor air samples should be biased toward areas of the building with the
greatest expected VI impact. Indoor air samples should be collected in the basement, if
present, or the lowest occupied floor. DEP recommends obtaining a concurrent ambient
air sample (in addition to at least two indoor samples) to account for potential
background contamination from outside the building.
The indoor air data collected for screening purposes should be collected when the daily
average outdoor temperature is at least 15°F below the minimum indoor temperature in
the occupied space and the heating system is operating normally. Indoor air sampling
can be performed during warmer seasons, but that data should be used for informational
purposes only and should not be used to screen out the VI pathway.
The remediator may initially characterize VI with a minimum of two rounds of near-
source soil gas, sub-slab soil gas, or indoor air sampling (Table 7). This data will
normally be collected during the site characterization, but it can also be obtained
following soil or groundwater remediation or during attainment monitoring. The two
sampling events should occur at least 45 days apart for statistical independence.
When preparing a sampling plan many factors should be considered (Appendix Z). Two
sample locations and two sampling rounds will not be sufficient at all sites and for all
buildings. Spatial and temporal variability of VI data is significant, and small data sets
have the potential of under-representing true mean concentrations and inhalation risks.
Larger buildings will likely require more samples as source concentrations, vapor entry
rates, and indoor ventilation rates will vary across the structure. If an undeveloped area is
being evaluated, then there will need to be enough near-source soil gas points to
encompass future building construction. Because petroleum hydrocarbons tend to pose a
relatively low risk for VI owing to bioattenuation, DEP regards chlorinated VOCs as a
greater concern for potential under-sampling.

261-0300-101 / DRAFT July 25, 2015 / Page 22
No further VI evaluation is necessary if none of the near-source soil gas, sub-slab soil
gas, or indoor air characterization data exceed screening values (SV
NS
, SV
SS
, SV
IA
). If
there are screening value exceedances, then the remediator has two options to continue
evaluating the VI pathway. One option is to collect sufficient near-source soil gas, sub-
slab soil gas, or indoor air data to apply statistical screening tests (Table 7). The other
option is to select another assessment or remedial alternative (Figure 5). For example, if
sub-slab sample results exceed screening values, then indoor air samples could be
collected and screened, a mitigation system could be installed, or a risk assessment could
be performed under the site-specific standard.
To screen near-source soil gas, sub-slab soil gas, and indoor air data using statistical tests,
at least eight data points must be obtained at the existing or potential future building.
This data can be a combination of sample locations and sampling rounds as long as there
are at least two rounds collected at all of the same points. Sample locations should be
biased toward areas with the greatest expected VI impact. The following soil and
groundwater statistical tests of Section 250.707(b) may be applied to the collective data
from the near-source soil gas, sub-slab soil gas, or indoor air sampling at each building:
?
Seventy-five percent of all samples shall be equal to or less than the applicable VI
screening value with no individual sample exceeding ten times the screening
value on the property (75%/10x rule) and two times the screening value beyond
the property boundary (75%/2x rule).
?
As applied in accordance with EPA-approved methods on statistical analysis of
environmental data, as identified in Section 250.707(e), the 95% upper confidence
limit of the arithmetic mean shall be at or below the applicable VI screening value
(95% UCL test). The minimum number of samples is specified by the method
documentation.
As an example, if there are two sub-slab sampling points in an onsite building that have
been sampled four times, the 75%/10x rule may be applied to those eight sets of
analytical results. These tests should not be used for combinations of near-source and
sub-slab data or soil gas and indoor air data. Data should be collected concurrently from
all sample locations at the building.
Near-source soil gas, sub-slab soil gas, and indoor air sampling rounds should be
performed in subsequent quarters or twice per quarter. Samples should be collected at
least 45 days apart. DEP may allow alternative sampling frequencies with prior written
approval.
G.4.
Vapor Intrusion Modeling
VI modeling can be used to predict indoor air concentrations in current or future
buildings. Modeling of any kind has an inherent amount of uncertainty involved but, if
acceptable input parameters are used with measured data, it can be a useful tool. The
J&E model is currently the most widely used and accepted VI model available. The J&E
model does have its limitations, namely it does not account for bioattenuation of
petroleum hydrocarbons in its predictions. As a result, other models, such as BioVapor,
can be used to predict indoor air concentrations at petroleum VI sites. Each model has its

261-0300-101 / DRAFT July 25, 2015 / Page 23
own set of conservative default input parameters that should be used when applicable.
However, some parameters such as soil type, permeability and depth to the source can be
adjusted to site-specific conditions.
Soil and groundwater data cannot be used for modeling if a preferential pathway or SPL
is present. In this situation, near-source soil gas data can be modeled to evaluate VI
provided that samples are collected directly above a preferential pathway and it does not
penetrate the building foundation. Likewise, near-source data may be collected above
SPL and used in the model.
For sites that are completely or partially undeveloped, many of the modeling input
parameters will have to be estimated. The remediator can use EPA’s default input
parameters (U.S. EPA, 2004) and information for future building plans. A list of input
parameters that can be adjusted based on site conditions is provided in the Modeling
Guidance presented in Appendix Y.
Pennsylvania versions of EPA’s J&E model spreadsheets are available on DEP’s website
and should be used for Statewide health standard J&E modeling. These versions have
DEP default parameter inputs as well as physical/chemical properties and toxicological
values from Chapter 250, Appendix A, Table 5A.
It is important to remember that when using VI modeling under the Statewide health
standard, the desired output is a predicted indoor air concentration. This modeled
concentration should be used in the evaluation of VI by comparing it to the associated
indoor air screening value or, under appropriate circumstances, occupational limits
acceptable in conjunction with an OSHA-compliant worker protection program. The
J&E model can calculate risk values, but these should not be used for Statewide health
standard evaluations. Use of risk calculations to evaluate VI is considered to be a risk
assessment, which is a tool to be used under the site-specific standard and is subject to
additional reporting requirements and fees. If calculated risk values are used in the VI
analysis, then the site is being remediated under a combination of standards and all
associated fees and requirements of both standards will apply.
H.
Mitigation and Environmental Covenants
Properly installed and maintained mitigation measures eliminate or greatly reduce VI exposure
and therefore remain protective regardless of changes in subsurface concentrations or toxicity
levels. Many areas of Pennsylvania have high levels of naturally occurring radon gas, which can
pose a significant public health threat. VI mitigation systems not only address potential VI
concerns associated with the release of regulated substances at remediation sites but also provide
additional public health benefits associated with reducing the significant threat caused by
naturally occurring radon gas. However, mitigation systems may not be feasible in all cases.
The feasibility of using a mitigation system to address VI impacts for existing buildings will
depend on the specific details of the site, the building, and the design of the system. Mitigation
most commonly involves the installation of an active sub-slab depressurization system (similar to
a fan-driven radon abatement system) (U.S. EPA, 2008).
For residential buildings, standard radon-type mitigation systems may be installed by individuals
or firms certified by DEP for radon mitigation pursuant to 25
Pa. Code
Chapter 240

261-0300-101 / DRAFT July 25, 2015 / Page 24
(Pennsylvania DEP, 1997). Standard residential systems do not need to be designed or approved
by a Licensed Professional Engineer. Active sub-slab depressurization systems can be tested
using pressure differential testing or indoor air sampling. Performance and testing guidelines for
these systems are provided in Appendix Z. The remediator must demonstrate depressurization
throughout the sub-slab. The remediator is not required to perform indoor air confirmation
sampling when active sub-slab depressurization systems are tested using pressure differential
testing.
An environmental covenant needs to be placed on the deed to ensure maintenance of the
mitigation system. The environmental covenant should include language that requires the
property owner to maintain the VI mitigation system. In most cases the environmental covenant
does not need to include language requiring periodic monitoring or reporting to DEP. DEP
should be notified in the event of a property transfer, if there is a problem with the system or
upon request by DEP.
Other engineering controls to mitigate VI, such as the installation of a vapor barrier engineered
to prevent VI, also require an environmental covenant for current and/or future buildings. Vapor
barriers should be designed and manufactured for use in VOC mitigation. The material should
be chemically resistant and have a demonstrated low permeability for the VOCs present.
Moisture barriers typically do not meet these criteria. Vapor barriers should be installed and
tested pursuant to the manufacturer’s recommendations.
Environmental covenants are needed for the following situations:
?
When using mitigation as a means of eliminating or reducing VI exposure at existing
structures.
?
When committing to mitigation (as described below) of future inhabited building on
the property.
?
When committing to evaluate Potential VI Sources at the time a future inhabited
building is constructed. The results of the evaluation should be submitted to DEP for
review.
?
When prohibiting construction of basements or residential and/or nonresidential
inhabited buildings in a specified area of the property where the VI pathway may be
complete.
?
When using an OSHA program to address Potential VI Sources in lieu of VI
evaluation under this section.
For example, Figure 3 depicts the proximity distance evaluation for a current building
(Section E). Contamination Zones B, C, D, E, and F also represent a Potential VI Source at the
site if a future inhabited building is constructed within the applicable proximity distances from
these five zones. Zone G, with the dotted perimeter in the map view, is the area within the
horizontal proximity distance from the Potential VI Source (Zones B and C) which exceeds soil
and/or groundwater screening values. The remediator could evaluate VI within Zone G, for
instance, with near-source soil gas sampling or modeling. Alternatively, the remediator could
incorporate activity and use limitations (AULs) in an environmental covenant requiring future

261-0300-101 / DRAFT July 25, 2015 / Page 25
evaluation if a new building is constructed, preemptive mitigation of new buildings, or the
prohibition of occupied buildings within Zone G.
Natural attenuation resulting in decreasing concentrations of soil and groundwater contamination
over time can occur at sites with releases of substances that naturally degrade in soil. At sites for
which an environmental covenant was used to address the VI pathway from Potential VI
Source(s), it may include a provision that allows for termination of the covenant or the AULs
related to VI if the remediator can demonstrate to DEP that the AUL(s) is/are no longer
necessary under current site conditions to comply with the selected standard.
The following language is provided as a guide for environmental covenants with only one AUL
related to VI:
This Environmental Covenant may be terminated if: (1) an evaluation is
performed that demonstrates that mitigation to address a complete or potentially
complete vapor intrusion pathway is no longer necessary and appropriate, and
(2) the Department reviews and approves the demonstration.
Alternatively, the following language is provided as a guide for environmental covenants with
multiple AULs including AULs unrelated to VI:
This Environmental Covenant may be modified with respect to the VI AUL if:
(1) an evaluation is performed that demonstrates that mitigation to address a
complete or potentially complete vapor intrusion pathway is no longer necessary
and appropriate, and (2) the Department reviews and approves the
demonstration.
I.
Remediating and Re-Assessing the VI Pathway
Under some circumstances mitigation may not be practical or cost effective. The remediator
may choose to perform further soil and/or groundwater remediation to address the VI pathway.
Following the remediation, additional data must be collected for VI screening. This can include
new soil or groundwater attainment data, or it can consist of soil gas or indoor air sampling data.
The post-remediation data is evaluated following the process illustrated in Figure 5 and
described in Sections G and H.
The timing of the remediation is an important consideration. If there is an excess VI risk but
remediation is a long-term action (such as a pump-and-treat system), then excess inhalation risks
may exist for an unacceptably long time. In such cases the remediator is responsible for
implementing interim measures to protect human health.
J.
Addressing Chapter 250 Requirements
The final step in the process flowchart on Figure 5 is to address the requirements of Chapter 250
with respect to VI. This step is necessary to demonstrate compliance with the Statewide health
standard in order to receive liability protection under Act 2. The submitted report should include
a description of the conceptual site model for VI with a preferential pathway assessment. The
flowchart endpoint can be reached in the following three ways, and compliance should be

261-0300-101 / DRAFT July 25, 2015 / Page 26
documented in either the final report (Chapter 250) or the site characterization and remedial
action completion reports (Chapter 245):
?
Soil and Groundwater Screening.
The remediator may screen soil and groundwater
concentration data within proximity distances. If no Potential VI Sources are identified,
then no further analysis is necessary. Maps and cross sections that show the spatial
relationship between soil and groundwater data, any SPL, any potential preferential
pathways, and existing or potential future inhabited structures should be used to
document that no Potential VI sources are present. Applicable proximity distances
should be shown on these exhibits. Soil and groundwater data should be tabulated and
compared to applicable screening values. If statistical methods for screening the data are
used, they should be explained.
?
Alternative Assessment Options.
The remediator may evaluate the VI pathway by
screening near-source soil gas, sub-slab soil gas, or indoor air data, or by performing
modeling. If the site data satisfy the screening criteria, then no further analysis is
necessary. Sampling locations relative to Potential VI Sources and existing or potential
future inhabited buildings should be shown on maps. The methodology for collecting the
samples should be described and the results tabulated with applicable screening values.
If statistical methods for screening the data are used, they should be explained. Refer to
Appendix Y for recommended modeling documentation.
?
Mitigation and Environmental Covenants.
The remediator may address the VI
pathway by installing a mitigation system or implementing activity and use limitations in
an environmental covenant. Installation of the mitigation system must be documented,
for instance with plans, manufacturer specifications, and the installer’s certification.
Testing to demonstrate the system’s effectiveness should be performed (Appendix Z) and
the results described in the report. If mitigation is successful, no further analysis is
required. The conditions to be included in a covenant to maintain the remedy or
eliminate the pathway should be detailed in the report.
When a Potential VI Source in soil or groundwater is remediated, new samples should be
collected to reevaluate the VI pathway and data should be presented as described above. If the
remediator chooses the site-specific standard to address VI, then the remediator should follow
the process and reporting described in Section K.
K.
Evaluating the VI Pathway under the Site-Specific Standard
K.1.
Overview
A site-specific standard VI evaluation may be required for one of two reasons:
?
Substances of potential VI concern in soil and/or groundwater do not attain the
Statewide health standard in those media;
?
Soil and groundwater attain the Statewide health standard in themselves, but the
site does not satisfy the Statewide health standard VI assessment process
described previously in this guidance.

261-0300-101 / DRAFT July 25, 2015 / Page 27
The site-specific VI evaluation process shares many elements with the Statewide health
standard process, but the screening values are not the same and a human health risk
assessment is an option. The site-specific standard VI process is outlined in Figure 6. It
is important to note that the purpose of Figure 6 is to illustrate how all of the steps in the
VI evaluation process under the site-specific standard fit together. Figure 6 should not be
used as the sole guide for performing a VI evaluation; rather, it should be used in
conjunction with the text of this guidance. The principal steps of a VI evaluation under
the site-specific standard are:
?
Develop the conceptual site model and assess preferential pathways;
?
Identify Potential VI Sources from conditions that limit screening and/or
exceedances of site-specific standard soil and groundwater screening values
within proximity distances;
?
Screen near-source soil gas, sub-slab soil gas, or indoor air data;
?
Perform a cumulative human health risk assessment, which may include
modeling;
?
Mitigate buildings and ensure future protection with an environmental covenant;
?
Remediate the soil and/or groundwater contamination and reassess the pathway;
?
Address the Chapter 250 site-specific standard requirements.
In most cases all of the above steps will not be necessary, and the remediator is not
required to follow the process sequentially. For instance, buildings with a potentially
complete VI pathway may be mitigated without the collection of soil gas or indoor air
data.
The Statewide health standard VI screening values presented earlier in this guidance are
based on either a carcinogenic target risk level of 10
–5
and a non-carcinogenic hazard
quotient of 1.0 or soil and groundwater MSCs. These screening values are not
appropriate for use in risk assessments being performed under the site-specific standard
because the Statewide health standard target risk levels and MSCs may not be sufficiently
conservative to account for cumulative risks to receptors from multiple contaminants
and/or multiple pathways.
K.2.
Preferential Pathway Evaluation
The remediator must assess potential preferential pathways as part of the site-specific
standard conceptual site model development (Section D). The presence of a preferential
pathway may preclude the use of proximity distances for the soil or groundwater
contaminant source area. Soil and groundwater screening values may not be used if
preferential pathways are present within proximity distances and they limit the use of
other assessment options.

261-0300-101 / DRAFT July 25, 2015 / Page 28
The conditions that are used to identify preferential pathways in Section D also apply
under the site-specific standard. Specifically, contamination in soil and groundwater that
exceeds Statewide health standard screening values within 30 horizontal and five vertical
feet of a preferential pathway constitutes a Potential VI Source (Figure 2). Acceptable
soil or soil-like material is qualified by no exceedances of Statewide health standard soil
screening values.
K.3.
Use of Proximity Distances
The remediator may utilize proximity distances to identify Potential VI Sources, as
described in Section E. For non-petroleum substances the horizontal proximity distance
is 100 feet, and for petroleum hydrocarbons it is 30 feet. When dissolved or adsorbed
petroleum hydrocarbons are at least six feet deep and petroleum SPL is at least 15 feet
deep, further VI evaluation is not required. These vertical separations must encompass
acceptable soil or soil-like material.
Potential VI Sources are established by the presence of SPL and exceedances of site-
specific standard soil and groundwater screening values within the applicable horizontal
proximity distance. Allowable site-specific screening values are one-tenth the Statewide
health standard screening values given in Tables 1 and 2, as explained in Section K.4.
For petroleum vertical proximity distances to apply there must be no exceedances of
Statewide health standard soil screening values in the upper six feet. Likewise,
acceptable soil or soil-like material is qualified by no exceedances of Statewide health
standard soil screening values.
K.4.
Site-Specific Standard VI Screening
Screening of soil, groundwater, near-source soil gas, sub-slab soil gas, and indoor air data
is available under the site-specific standard. Samples should be collected pursuant to the
guidance in Table 6 and Appendix Z. An assessment of preferential pathways and the
presence of SPL needs to be performed prior to screening as these are conditions that can
limit the use of screening values.
If no limiting conditions exist, then soil and groundwater data may be screened using
site-specific standard screening values. If limiting conditions are present, near-source
soil gas, sub-slab soil gas, and indoor air may be screened with the following exceptions:
?
Near-source soil gas screening cannot be performed if there is a source less than
five feet below the building foundation or if a preferential pathway penetrates the
building foundation.
?
Sub-slab soil gas screening may not be performed if a preferential pathway
penetrates the building foundation.
The Statewide health standard VI screening values listed in Tables 1 through 5 may
not
be used for site-specific standard screening.
The Statewide health standard criteria
are based on a 10
–5
target cancer risk and a 1.0 target hazard quotient or MSCs (Appendix
X). Attainment for the site-specific standard is demonstrated for cumulative risks to

261-0300-101 / DRAFT July 25, 2015 / Page 29
receptors from all substances, media, and pathways. VI evaluations using a combination
of standards is discussed in Section C.3.
DEP recommends the use of substance-by-substance site-specific standard VI screening
values using either of the following methods:
?
Select the appropriate values for soil, groundwater, near-source soil gas, sub-slab
soil gas, or indoor air from Tables 1 through 5 and reduce them by a factor of 10.
?
Use the current EPA residential or industrial indoor air Regional Screening Level
(RSL) values (based on a target cancer risk of 10
–6
and a target hazard quotient
of 0.1) (U.S. EPA, 2015). RSLs based on a 10
–5
cancer risk may be used for
screening when it can be demonstrated that VI is the only complete exposure
pathway for a receptor. RSLs may be used for screening indoor air data or for
screening near-source or sub-slab soil gas data by using the following attenuation
factors (refer to Appendix X):
Environmental Medium
Attenuation Factor
Residential
Non-
Residential
Converted
Residential
Sub-slab soil gas
0.026
0.0078
0.026
Near-source soil gas
0.005
0.001
0.005
The methodology for soil and groundwater screening is described in Section F.2, and the
methods for near-source soil gas, sub-slab soil gas, and indoor air are provided in
Section G.3. Screening may be applied to characterization and post-remediation data. A
sufficient number of sample locations and rounds must be collected to satisfactorily
evaluate the pathway. DEP recommends a minimum of two sample locations and two
sampling rounds for screening.
For the site-specific standard the only acceptable screening criterion is no exceedances of
the applicable screening values. Substances that screen out using either one-tenth of the
Statewide health standard VI screening values or the EPA RSLs do not need to be
included in a VI risk assessment.
K.5.
Performing a VI Risk Assessment and Modeling
In a risk assessment, the VI pathway should be considered when developing the CSM.
The CSM should use a qualitative fate and transport analysis to identify all current and
future potentially complete and incomplete exposure pathways, including source media,
transport mechanisms, and all potential receptors (Section 250.404). The risks associated
with all complete exposure pathways must be combined for individual receptors in order
to evaluate the total cumulative risk to each receptor. For example, if ingestion of
contaminated soil, dermal contact with contaminated groundwater, and inhalation of
vapor-phase contamination via VI are all complete exposure pathways for the same
receptor, the calculated risk values for each of these pathways must be combined to
evaluate the total risk to the receptor.

261-0300-101 / DRAFT July 25, 2015 / Page 30
Current toxicity values should be used in a site-specific standard risk assessment
(Section 250.605). Therefore, if a toxicity value has been updated since the last revision
of the Statewide health standard screening values, that new information must be included
in a cumulative risk assessment. This provision is in keeping with DEP’s discretion in
allowing screening to substitute for a risk assessment.
VI modeling is one option for site-specific standard risk assessments. DEP’s modeling
guidance is provided in Appendix Y. For site-specific standard modeling, the user inputs
soil, groundwater, or near-source soil gas concentrations into the Pennsylvania versions
of EPA’s J&E models. The desired output is the incremental risks for each substance,
not
the predicted indoor air concentrations. The model risk results are then incorporated
into the cumulative risk assessment.
The second option is to use indoor air, sub-slab soil gas, or near-source soil gas data for
the risk assessment. Soil gas data must be converted to estimated indoor air
concentrations using the conservative attenuation factors tabulated in Section K.4.
Inhalation risks are calculated using standard equations. (See Appendices X and Y.)
The VI risk assessment must be submitted in a risk assessment report meeting the
procedural and substantive requirements of Act 2. For regulated storage tank sites the
risk assessment is provided in the site characterization and remedial action completion
reports. Human health risk assessment guidance is found in Section IV.G of the
Technical Guidance Manual (TGM). Screening of chemicals of concern may follow the
methodology described in Section K.4.
K.6.
Mitigation and Remediation
If site contamination does not screen out using the site-specific standard screening values
or the cumulative risks are excessive, then the remediator may choose to take an active
approach to addressing VI. These options include mitigation and remediation.
Buildings may be mitigated to eliminate the VI pathway (Section H). Mitigation
measures are considered to be engineering controls because they prevent the migration of
vapor. The standard mitigation approach is an active sub-slab depressurization system
(U.S. EPA, 2008). Performance and testing guidelines are provided in Appendix Z.
Mitigation systems installed on current buildings or planned for future construction must
be implemented with an environmental covenant placed on the property deed.
Remediation of soil and/or groundwater is also an alternative to address the VI pathway
(Section I). Post-remediation data must be collected and evaluated through screening or a
risk assessment. If remedial action is not completed promptly, then the remediator may
be responsible for employing interim measures to protect human health.
K.7.
Addressing Chapter 250 Requirements
The final step in the process flowchart in Figure 6 is to address the requirements of
Chapter 250 with respect to VI. This step is necessary to demonstrate compliance with
the site-specific standard under Act 2. The submitted report should include a description
of the CSM for VI with a preferential pathway assessment. The flowchart endpoint can

261-0300-101 / DRAFT July 25, 2015 / Page 31
be reached in the following four ways and compliance documented in Act 2
(Chapter 250) or corrective action (Chapter 245) reports:
?
Soil and Groundwater Screening.
The remediator may screen soil and
groundwater concentration data within proximity distances. If no Potential VI
Sources are identified, then no further analysis is necessary. Documenting this
conclusion requires the production of maps and cross sections that show the
spatial relationship between soil and groundwater data, any SPL, any potential
preferential pathways, and existing or potential future inhabited structures.
Applicable proximity distances should be shown on these exhibits. Soil and
groundwater data should be tabulated and compared to applicable screening
values. This information is submitted in the remedial investigation and final
reports or the site characterization and remedial action completion reports, as
appropriate.
?
Alternative Assessment Options.
The remediator may evaluate the VI pathway
by screening near-source soil gas, sub-slab soil gas, or indoor air data. If the site
data satisfy the screening criteria, then no further analysis is necessary. Sampling
locations relative to Potential VI Sources and existing or potential future inhabited
buildings should be shown on maps. The methodology for collecting the samples
should be described and the results tabulated with applicable screening values.
Supporting information is submitted in the remedial investigation and final reports
or the site characterization and remedial action completion reports, as appropriate.
?
Risk Assessment.
If VI screening values are not applicable or they are exceeded,
then a human health risk assessment may be performed. If the site-specific risk
thresholds (cumulative 10
–4
cancer risk and hazard index of 1.0) are satisfied, no
further analysis is required. Risk assessment requirements are described in
Section 250.409 and the TGM, Section IV.G. Documentation is supplied in a risk
assessment report or a risk assessment submitted as part of a site characterization
report and remedial action completion report, as appropriate. The risk evaluation
may include modeling, as described in Appendix Y.
?
Mitigation and Environmental Covenants.
The remediator may address the VI
pathway by installing a mitigation system or implementing AULs in an
environmental covenant. Installation of the mitigation system must be
documented, for instance with plans, manufacturer specifications, and the
installer’s certification. Testing to demonstrate the system’s effectiveness should
be performed (Appendix Z) and the results described in the report. If mitigation
is successful, no further analysis is required. The conditions to be included in a
covenant to maintain the remedy or eliminate the pathway should also be detailed
in the report. Documentation for mitigation systems and covenant remedies is
provided in the final report or remedial action completion report, as appropriate.
When a Potential VI Source in soil or groundwater is remediated, new samples are
collected to reevaluate the VI pathway. That data is presented as described above for the
site-specific standard or through the Statewide health standard process, as appropriate.

261-0300-101 / DRAFT July 25, 2015 / Page 32
Figure 5. Statewide Health Standard Vapor Intrusion Assessment Process
Assess the VI pathway with modeling
Calculate and screen modeled indoor air concentrations
using soil, groundwater, or near-source soil gas data
in accordance with Section G.4 and Appendix Y.
Assess the VI pathway using Statewide health
standard soil gas or indoor air screening values
Perform near-source soil gas, sub-slab soil gas, or
indoor air screening using the corresponding SHS
screening values in accordance with Section G.
1. APPLY ALTERNATIVE VI ASSESSMENT
OPTIONS TO POTENTIAL VI SOURCES
No further VI analysis is necessary.
Address Chapter 250 requirements in
accordance with Section I.
ADDRESS CH. 250
REQUIREMENTS
Start Here
DELINEATE POTENTIAL VI SOURCES
AT ANY POINT IN THE VI ASSESSMENT
PROCESS THE REMEDIATOR MAY
MITIGATE, REMEDIATE, OR CHOOSE
THE SITE-SPECIFIC STANDARD TO
EVALUATE VI IN ACCORDANCE WITH
SECTIONS H, I, AND K, RESPECTIVELY.
Develop and consult a Conceptual Site Model and delineate
concentrations of soil and groundwater constituents
3. REMEDIATE AND REEVALUATE THE
VI PATHWAY
Implement in accordance with Section I.
2. MITIGATE, TEST, AND IMPLEMENT AN
ENVIRONMENTAL COVENANT
Implement in accordance with Section H.
4. SELECT THE SITE-SPECIFIC STANDARD
Follow the SSS process in accordance with Section K.
Apply Proximity Distances
Apply petroleum and non-petroleum
proximity distances as appropriate in
accordance with Section E.
SCREEN FOR POTENTIAL VI
SOURCES
(Address both screens.)
Identify Preferential Pathways
Identify potential preferential pathways in
accordance with Section D.
If soil and groundwater screening value exceedences and SPL
are NOT within proximity distances of preferential pathways
or current or future inhabited structures,
no further VI
analysis is necessary
. Address Chapter 250 requirements in
accordance with Section I.
If soil or groundwater screening value exceedences or SPL is
within proximity distances to preferential pathways or current
or future inhabited structures, choose from the following
options:
1.
Alternative VI assessment options.
2.
Mitigation with an Environmental Covenant.
3.
Remediation and reevaluation of VI pathway.
4.
Evaluation of the VI pathway using the site-specific
standard.

261-0300-101 / DRAFT July 25, 2015 / Page 33
Figure 6. Site-Specific Standard Vapor Intrusion Assessment Process
Perform a risk assessment
Perform a risk assessment which evaluates cumulative
risks and may include VI modeling. Refer to
Section K.5 and Appendix Y for further guidance.
Assess the VI pathway using the
site-specific standard screening process
Perform near-source soil gas, sub-slab soil gas, or
indoor air screening using the corresponding SSS
screening values in accordance with Section K.4.
1. APPLY ALTERNATIVE VI ASSESSMENT
OPTIONS TO POTENTIAL VI SOURCES
Apply Proximity Distances
Apply petroleum and non-petroleum
proximity distances as appropriate in
accordance with Section K.3.
SCREEN FOR POTENTIAL VI
SOURCES
(Address both screens.)
No further VI analysis is necessary.
Address Chapter 250 requirements in
accordance with Section K.7.
ADDRESS CH. 250
REQUIREMENTS
Start Here
DELINEATE POTENTIAL VI SOURCES
If soil and groundwater screening value exceedences and SPL
are NOT within proximity distances of preferential pathways or
current or future inhabited structures,
no further VI analysis is
necessary
. Address Chapter 250 requirements in accordance
with Section K.7.
If soil or groundwater screening value exceedences or SPL is
within proximity distances to preferential pathways or current
or future inhabited structures, choose from the following
options:
1.
Alternative VI assessment options.
2.
Mitigation with an Environmental Covenant.
3.
Remediation and reevaluation of VI pathway.
AT ANY POINT IN THE VI
ASSESSMENT PROCESS THE
REMEDIATOR MAY MITIGATE OR
REMEDIATE TO ADDRESS VI UNDER
THE SITE-SPECIFIC STANDARD IN
ACCORDANCE WITH SECTION K.6.
Develop and consult a Conceptual Site Model and delineate
concentrations of soil and groundwater constituents.
3. REMEDIATE AND REEVALUATE THE
VI PATHWAY
Implement in accordance with Section K.6.
2. MITIGATE, TEST, AND IMPLEMENT AN
ENVIRONMENTAL COVENANT
Implement in accordance with Section K.6.
Identify Preferential Pathways
Identify potential preferential pathways
in accordance with Section K.2.

261-0300-101 / DRAFT July 25, 2015 / Page 34
Table 1. Groundwater Statewide Health Standard Vapor Intrusion Screening Values (SVGW)
Regulated Substance
CAS No.
Residential
(
?
g/L)
?
Type
Nonresidentia
l
(
?
g/L)
Type
Converted
Residential
(
?
g/L)
Type
ACETALDEHYDE
75-07-0
4,800
SV
68,000
SV
20,000
SV
ACETONE
67-64-1
35,000,000
SV
490,000,000
SV
150,000,000
SV
ACETONITRILE
75-05-8
72,000
SV
1,000,000
SV
300,000
SV
ACROLEIN
107-02-8
6.4
SV
89
SV
27
SV
ACRYLAMIDE
79-06-1
3,700,000
SV
160,000,000
SV
47,000,000
SV
ACRYLIC ACID
79-10-7
170,000
SV
2,400,000
SV
730,000
SV
ACRYLONITRILE
107-13-1
110
SV
1,900
SV
560
SV
ALLYL ALCOHOL
107-18-6
1,100
SV
15,000
SV
4,500
SV
AMMONIA
7664-41-7
200,000
SV
2,800,000
SV
840,000
SV
ANILINE
62-53-3
29,000
SV
410,000
SV
120,000
SV
BENZENE
71-43-2
23
SV
380
SV
110
SV
BENZYL CHLORIDE
100-44-7
60
SV
1,000
SV
300
SV
BETA PROPIOLACTONE
57-57-8
0.012
MSC
0.063
MSC
0.063
MSC
BIPHENYL, 1,1-
92-52-4
91
MSC
1,200
SV
430
MSC
BIS(2-CHLOROETHYL)ETHER
111-44-4
270
SV
4,600
SV
1,400
SV
BIS(2-CHLORO-ISOPROPYL)ETHER
108-60-1
1,800
SV
31,000
SV
9,200
SV
BIS(CHLOROMETHYL)ETHER
542-88-1
0.0040
SV
0.067
SV
0.020
SV
BROMOCHLOROMETHANE
74-97-5
1,100
SV
16,000
SV
4,800
SV
BROMODICHLOROMETHANE
75-27-4
80
MSC
220
SV
80
MSC
BROMOMETHANE
74-83-9
23
SV
320
SV
97
SV
BUTADIENE, 1,3-
106-99-0
0.35
SV
5.8
SV
1.7
SV
CARBON DISULFIDE
75-15-0
1,800
SV
25,000
SV
7,600
SV
CARBON TETRACHLORIDE
56-23-5
5.8
SV
97
SV
29
SV
CHLORO-1,1-DIFLUOROETHANE, 1-
75-68-3
1,200,000
SV
1,400,000
Sol.
1,400,000
Sol.
CHLORO-1-PROPENE, 3- (ALLYL CHLORIDE)
107-05-1
3.6
SV
50
SV
15
SV
CHLOROBENZENE
108-90-7
770
SV
11,000
SV
3,200
SV
CHLORODIBROMOMETHANE
124-48-1
80
MSC
680
SV
200
SV
CHLORODIFLUOROMETHANE
75-45-6
110,000
MSC
520,000
SV
440,000
MSC
CHLOROETHANE
75-00-3
31,000
SV
440,000
SV
130,000
SV
CHLOROFORM
67-66-3
80
MSC
190
SV
80
MSC
CHLOROPRENE
126-99-8
0.16
MSC
1.0
MSC
0.83
MSC
CHLOROPROPANE, 2-
75-29-6
210
SV
3,000
SV
890
SV
CRESOL(S)
1319-77-3
20,000,000
Sol.
20,000,000
Sol.
20,000,000
Sol.

261-0300-101 / DRAFT July 25, 2015 / Page 35
Regulated Substance
CAS No.
Residential
(
?
g/L)
?
Type
Nonresidentia
l
(
?
g/L)
Type
Converted
Residential
(
?
g/L)
Type
CUMENE (ISOPROPYL BENZENE)
98-82-8
2,100
SV
30,000
SV
8,900
SV
CYCLOHEXANE
110-82-7
13,000
MSC
53,000
MSC
53,000
MSC
CYCLOHEXANONE
108-94-1
4,300,000
SV
37,000,000
Sol.
18,000,000
SV
DIBROMO-3-CHLOROPROPANE, 1,2-
96-12-8
0.62
SV
27
SV
8.0
SV
DIBROMOETHANE, 1,2- (ETHYLENE
DIBROMIDE)
106-93-4
3.0
SV
50
SV
15
SV
DIBROMOMETHANE
74-95-3
220
SV
3,000
SV
910
SV
DICHLORO-2-BUTENE, 1,4-
764-41-0
0.44
SV
7.3
SV
2.2
SV
DICHLORO-2-BUTENE, TRANS-1,4-
110-57-6
0.45
SV
7.5
SV
2.2
SV
DICHLOROBENZENE, 1,2-
95-50-1
5,900
SV
82,000
SV
25,000
SV
DICHLOROBENZENE, P-
106-46-7
75
MSC
800
SV
240
SV
DICHLORODIFLUOROMETHANE (FREON 12)
75-71-8
1,000
MSC
1,000
MSC
1,000
MSC
DICHLOROETHANE, 1,1-
75-34-3
100
SV
1,700
SV
520
SV
DICHLOROETHANE, 1,2-
107-06-2
33
SV
550
SV
170
SV
DICHLOROETHYLENE, 1,1-
75-35-4
280
SV
3,900
SV
1,200
SV
DICHLOROETHYLENE, TRANS-1,2-
156-60-5
570
SV
7,900
SV
2,400
SV
DICHLOROMETHANE (METHYLENE
CHLORIDE)
75-09-2
7,000
SV
99,000
SV
30,000
SV
DICHLOROPROPANE, 1,2-
78-87-5
36
SV
610
SV
180
SV
DICHLOROPROPENE, 1,3-
542-75-6
75
SV
1,300
SV
380
SV
DICYCLOPENTADIENE
77-73-6
0.63
MSC
2.6
MSC
2.6
MSC
DIOXANE, 1,4-
123-91-1
31,000
SV
510,000
SV
150,000
SV
EPICHLOROHYDRIN
106-89-8
700
SV
9,800
SV
2,900
SV
ETHOXYETHANOL, 2- (EGEE)
110-80-5
24,000,000
SV
340,000,000
SV
100,000,000
SV
ETHYL ACETATE
141-78-6
23,000
SV
320,000
SV
96,000
SV
ETHYL ACRYLATE
140-88-5
1,100
SV
16,000
SV
4,700
SV
ETHYL BENZENE
100-41-4
700
SV
980
SV
700
SV
ETHYL METHACRYLATE
97-63-2
33,000
SV
460,000
SV
140,000
SV
ETHYLENE GLYCOL
107-21-1
510,000,000
SV
1,000,000,000
Sol.
1,000,000,000
Sol.
FLUOROTRICHLOROMETHANE (FREON 11)
75-69-4
2,000
MSC
3,600
SV
2,000
MSC
FORMALDEHYDE
50-00-0
170,000
SV
2,900,000
SV
870,000
SV
FORMIC ACID
64-18-6
63,000
SV
880,000
SV
260,000
SV
FURFURAL
98-01-1
750,000
SV
11,000,000
SV
3,200,000
SV
HEXACHLOROETHANE
67-72-1
34
SV
570
SV
170
SV
HEXANE
110-54-3
1,500
MSC
6,200
MSC
6,200
MSC

261-0300-101 / DRAFT July 25, 2015 / Page 36
Regulated Substance
CAS No.
Residential
(
?
g/L)
?
Type
Nonresidentia
l
(
?
g/L)
Type
Converted
Residential
(
?
g/L)
Type
HYDRAZINE/HYDRAZINE SULFATE
302-01-2
450
SV
7,500
SV
2,300
SV
METHACRYLONITRILE
126-98-7
5,300
SV
74,000
SV
22,000
SV
METHANOL
67-56-1
41,000,000
SV
570,000,000
SV
170,000,000
SV
METHOXYETHANOL, 2-
109-86-4
3,100,000
SV
44,000,000
SV
13,000,000
SV
METHYL ACRYLATE
96-33-3
4,300
SV
61,000
SV
18,000
SV
METHYL CHLORIDE
74-87-3
46
SV
780
SV
230
SV
METHYL ETHYL KETONE
78-93-3
3,800,000
SV
53,000,000
SV
16,000,000
SV
METHYL HYDRAZINE
60-34-4
320
SV
4,500
SV
1,300
SV
METHYL ISOBUTYL KETONE
108-10-1
1,100,000
SV
15,000,000
SV
4,400,000
SV
METHYL ISOCYANATE
624-83-9
40
SV
560
SV
170
SV
METHYL METHACRYLATE
80-62-6
110,000
SV
1,500,000
SV
460,000
SV
METHYL N-BUTYL KETONE (2-HEXANONE)
591-78-6
16,000
SV
230,000
SV
68,000
SV
METHYL STYRENE (MIXED ISOMERS)
25013-15-4
1,100
SV
16,000
SV
4,800
SV
METHYL TERT-BUTYL ETHER (MTBE)
1634-04-4
6,000
SV
100,000
SV
30,000
SV
METHYLNAPHTHALENE, 2-
91-57-6
480
SV
6,700
SV
2,000
SV
NAPHTHALENE
91-20-3
100
SV
1,600
SV
490
SV
NITROBENZENE
98-95-3
1,600
SV
26,000
SV
7,900
SV
NITROPROPANE, 2-
79-46-9
3.5
SV
59
SV
18
SV
NITROSODIETHYLAMINE, N-
55-18-5
3.6
SV
150
SV
46
SV
NITROSODIMETHYLAMINE, N-
62-75-9
20
SV
850
SV
250
SV
NITROSO-DI-N-BUTYLAMINE, N-
924-16-3
130
SV
2,200
SV
650
SV
PCB-1221 (AROCLOR)
11104-28-2
4.2
SV
71
SV
21
SV
PCB-1232 (AROCLOR)
11141-16-5
4.4
SV
74
SV
22
SV
PHENOL
108-95-2
39,000,000
SV
84,000,000
Sol.
84,000,000
Sol.
PROPANOL, 2- (ISOPROPYL ALCOHOL)
67-63-0
1,300,000
SV
19,000,000
SV
5,600,000
SV
PROPYLBENZENE, N-
103-65-1
5,200
SV
52,000
Sol.
22,000
SV
PROPYLENE OXIDE
75-56-9
3,400
SV
58,000
SV
17,000
SV
STYRENE
100-42-5
18,000
SV
260,000
SV
77,000
SV
TETRACHLOROETHANE, 1,1,1,2-
630-20-6
70
MSC
1,200
SV
350
SV
TETRACHLOROETHANE, 1,1,2,2-
79-34-5
56
SV
940
SV
280
SV
TETRACHLOROETHYLENE (PCE)
127-18-4
110
SV
1,500
SV
450
SV
TETRAHYDROFURAN
109-99-9
26
MSC
130
MSC
130
MSC
TOLUENE
108-88-3
34,000
SV
480,000
SV
140,000
SV
TRIBROMOMETHANE (BROMOFORM)
75-25-2
2,100
SV
35,000
SV
10,000
SV
TRICHLORO-1,2,2-TRIFLUOROETHANE, 1,1,2-
76-13-1
63,000
MSC
170,000
MSC
170,000
MSC

261-0300-101 / DRAFT July 25, 2015 / Page 37
Regulated Substance
CAS No.
Residential
(
?
g/L)
?
Type
Nonresidentia
l
(
?
g/L)
Type
Converted
Residential
(
?
g/L)
Type
TRICHLOROBENZENE, 1,2,4-
120-82-1
90
SV
1,300
SV
380
SV
TRICHLOROBENZENE, 1,3,5-
108-70-3
66
SV
930
SV
280
SV
TRICHLOROETHANE, 1,1,1-
71-55-6
12,000
SV
170,000
SV
50,000
SV
TRICHLOROETHANE, 1,1,2-
79-00-5
11
SV
160
SV
48
SV
TRICHLOROETHYLENE (TCE)
79-01-6
8.8
SV
120
SV
37
SV
TRICHLOROPROPANE, 1,2,3-
96-18-4
47
SV
650
SV
200
SV
TRICHLOROPROPENE, 1,2,3-
96-19-5
0.86
SV
12
SV
3.6
SV
TRIETHYLAMINE
121-44-8
2,200
SV
31,000
SV
9,200
SV
TRIMETHYLBENZENE, 1,3,4-
(TRIMETHYLBENZENE, 1,2,4-)
95-63-6
64
SV
890
SV
270
SV
TRIMETHYLBENZENE, 1,3,5-
108-67-8
420
MSC
1,200
MSC
1,200
MSC
VINYL ACETATE
108-05-4
17,000
SV
240,000
SV
72,000
SV
VINYL BROMIDE (BROMOETHENE)
593-60-2
2.0
SV
33
SV
10
SV
VINYL CHLORIDE
75-01-4
2.0
MSC
51
SV
15
SV
XYLENES (TOTAL)
1330-20-7
10,000
MSC
14,000
SV
10,000
MSC
Note:
These groundwater screening values apply to depths of five feet or greater below the bottom of the building foundation.
Screening values for depths less than five feet are the used aquifer groundwater MSCs (Title 25
Pa. Code
Ch. 250, Appendix A, Table 1)
Type:
SV—calculated screening value
MSC—medium specific concentration (Title 25
Pa. Code
Ch. 250, Appendix A, Table 1)
Sol.—aqueous solubility

261-0300-101 / DRAFT July 25, 2015 / Page 38
Table 2. Soil Statewide Health Standard Vapor Intrusion Screening Values (SV
soil
)
Regulated Substance
CAS No.
Residential
(mg/kg)
Type
Nonresidential
(mg/kg)
Type
Converted
Residential
(mg/kg)
Type
ACETALDEHYDE
75-07-0
0.23
SGN
0.96
SGN
0.96
SGN
ACETONE
67-64-1
430
SGN
6,000
SV
1,200
SV
ACETONITRILE
75-05-8
1.5
SGN
12
SV
6.0
SGN
ACROLEIN
107-02-8
0.00047
SGN
0.002
SGN
0.0020
SGN
ACRYLAMIDE
79-06-1
57
SV
3,700
SV
730
SV
ACRYLIC ACID
79-10-7
2.9
SV
61
SV
12
SV
ACRYLONITRILE
107-13-1
0.01
SGN
0.051
SGN
0.051
SGN
ALLYL ALCOHOL
107-18-6
0.0097
SV
0.2
SV
0.041
SV
AMMONIA
7664-41-7
360
SGN
360
SGN
360
SGN
ANILINE
62-53-3
1.9
SV
40
SV
7.9
SV
BENZENE
71-43-2
0.13
SGN
0.13
SGN
0.13
SGN
BENZYL CHLORIDE
100-44-7
0.059
SGN
0.30
SGN
0.30
SGN
BETA PROPIOLACTONE
57-57-8
0.00015
SGN
0.00076
SGN
0.00076
SGN
BIPHENYL, 1,1-
92-52-4
40
SGN
190
SGN
190
SGN
BIS(2-CHLOROETHYL)ETHER
111-44-4
0.0085
SV
0.21
SV
0.043
SV
BIS(2-CHLORO-ISOPROPYL)ETHER
108-60-1
8.0
SGN
8.0
SGN
8.0
SGN
BIS(CHLOROMETHYL)ETHER
542-88-1
0.000012
SGN
0.000060
SGN
0.000060
SGN
BROMOCHLOROMETHANE
74-97-5
1.6
SGN
1.6
SGN
1.6
SGN
BROMODICHLOROMETHANE
75-27-4
2.7
SGN
2.7
SGN
2.7
SGN
BROMOMETHANE
74-83-9
0.54
SGN
0.54
SGN
0.54
SGN
BUTADIENE, 1,3-
106-99-0
0.0086
SGN
0.041
SGN
0.041
SGN
CARBON DISULFIDE
75-15-0
130
SGN
530
SGN
530
SGN
CARBON TETRACHLORIDE
56-23-5
0.26
SGN
0.26
SGN
0.26
SGN
CHLORO-1,1-DIFLUOROETHANE, 1-
75-68-3
1,800
SGN
7,300
SGN
7,300
SGN
CHLORO-1-PROPENE, 3- (ALLYL CHLORIDE)
107-05-1
0.049
SGN
0.20
SGN
0.20
SGN
CHLOROBENZENE
108-90-7
6.1
SGN
6.1
SGN
6.1
SGN
CHLORODIBROMOMETHANE
124-48-1
2.5
SGN
2.5
SGN
2.5
SGN
CHLORODIFLUOROMETHANE
75-45-6
2,800
SGN
10,000
SGN
10,000
SGN
CHLOROETHANE
75-00-3
5.4
SGN
26
SGN
26
SGN
CHLOROFORM
67-66-3
2.0
SGN
2.0
SGN
2.0
SGN
CHLOROPRENE
126-99-8
0.0038
SGN
0.020
SGN
0.020
SGN
CHLOROPROPANE, 2-
75-29-6
16
SGN
67
SGN
67
SGN
CRESOL(S)
1319-77-3
460
SV
9,600
SV
1,900
SV

261-0300-101 / DRAFT July 25, 2015 / Page 39
Regulated Substance
CAS No.
Residential
(mg/kg)
Type
Nonresidential
(mg/kg)
Type
Converted
Residential
(mg/kg)
Type
CUMENE (ISOPROPYL BENZENE)
98-82-8
600
SGN
2,500
SGN
2,500
SGN
CYCLOHEXANE
110-82-7
1,700
SGN
6,900
SGN
6,900
SGN
CYCLOHEXANONE
108-94-1
120
SV
2,500
SV
500
SV
DIBROMO-3-CHLOROPROPANE, 1,2-
96-12-8
0.0092
SGN
0.0092
SGN
0.0092
SGN
DIBROMOETHANE, 1,2- (ETHYLENE
DIBROMIDE)
106-93-4
0.0012
SGN
0.0018
SV
0.0012
SGN
DIBROMOMETHANE
74-95-3
0.32
SGN
1.4
SGN
1.4
SGN
DICHLORO-2-BUTENE, 1,4-
764-41-0
0.00067
SGN
0.0034
SGN
0.0034
SGN
DICHLORO-2-BUTENE, TRANS-1,4-
110-57-6
0.00078
SGN
0.0039
SGN
0.0039
SGN
DICHLOROBENZENE, 1,2-
95-50-1
59
SGN
59
SGN
59
SGN
DICHLOROBENZENE, P-
106-46-7
10
SGN
10
SGN
10
SGN
DICHLORODIFLUOROMETHANE (FREON 12)
75-71-8
100
SGN
100
SGN
100
SGN
DICHLOROETHANE, 1,1-
75-34-3
0.75
SGN
3.9
SGN
3.9
SGN
DICHLOROETHANE, 1,2-
107-06-2
0.10
SGN
0.10
SGN
0.10
SGN
DICHLOROETHYLENE, 1,1-
75-35-4
0.19
SGN
0.19
SGN
0.19
SGN
DICHLOROETHYLENE, TRANS-1,2-
156-60-5
2.3
SGN
2.3
SGN
2.3
SGN
DICHLOROMETHANE (METHYLENE
CHLORIDE)
75-09-2
0.09
SV
1.9
SV
0.38
SV
DICHLOROPROPANE, 1,2-
78-87-5
0.11
SGN
0.11
SGN
0.11
SGN
DICHLOROPROPENE, 1,3-
542-75-6
0.13
SGN
0.61
SGN
0.61
SGN
DICYCLOPENTADIENE
77-73-6
0.13
SGN
0.56
SGN
0.56
SGN
DIOXANE, 1,4-
123-91-1
0.32
SV
8
SV
1.6
SV
EPICHLOROHYDRIN
106-89-8
0.042
SGN
0.27
SV
0.17
SGN
ETHOXYETHANOL, 2- (EGEE)
110-80-5
280
SV
5,900
SV
1,200
SV
ETHYL ACETATE
141-78-6
3.9
SGN
16
SGN
16
SGN
ETHYL ACRYLATE
140-88-5
0.58
SGN
2.7
SGN
2.7
SGN
ETHYL BENZENE
100-41-4
46
SGN
46
SGN
46
SGN
ETHYL METHACRYLATE
97-63-2
10
SGN
43
SGN
43
SGN
ETHYLENE GLYCOL
107-21-1
4,800
SV
10,000
SAT
10,000
SAT
FLUOROTRICHLOROMETHANE (FREON 11)
75-69-4
87
SGN
87
SGN
87
SGN
FORMALDEHYDE
50-00-0
12
SGN
40
SV
12
SGN
FORMIC ACID
64-18-6
0.5
SV
11
SV
2.1
SV
FURFURAL
98-01-1
7.4
SV
160
SV
31
SV
HEXACHLOROETHANE
67-72-1
0.56
SGN
0.57
SV
0.56
SGN
HEXANE
110-54-3
1,400
SGN
5,600
SGN
5,600
SGN

261-0300-101 / DRAFT July 25, 2015 / Page 40
Regulated Substance
CAS No.
Residential
(mg/kg)
Type
Nonresidential
(mg/kg)
Type
Converted
Residential
(mg/kg)
Type
HYDRAZINE/HYDRAZINE SULFATE
302-01-2
0.0036
SV
0.09
SV
0.018
SV
METHACRYLONITRILE
126-98-7
0.076
SV
1.6
SV
0.32
SV
METHANOL
67-56-1
360
SV
7,500
SV
1,500
SV
METHOXYETHANOL, 2-
109-86-4
25
SV
520
SV
100
SV
METHYL ACRYLATE
96-33-3
1.0
SGN
4.5
SGN
4.5
SGN
METHYL CHLORIDE
74-87-3
0.38
SGN
0.38
SGN
0.38
SGN
METHYL ETHYL KETONE
78-93-3
76
SGN
1,400
SV
280
SV
METHYL HYDRAZINE
60-34-4
0.0027
SV
0.056
SV
0.011
SV
METHYL ISOBUTYL KETONE
108-10-1
51
SGN
290
SV
140
SGN
METHYL ISOCYANATE
624-83-9
0.029
SGN
0.12
SGN
0.12
SGN
METHYL METHACRYLATE
80-62-6
20
SGN
84
SGN
84
SGN
METHYL N-BUTYL KETONE (2-HEXANONE)
591-78-6
1.6
SGN
8.2
SV
6.4
SGN
METHYL STYRENE (MIXED ISOMERS)
25013-15-4
47
SGN
200
SGN
200
SGN
METHYL TERT-BUTYL ETHER (MTBE)
1634-04-4
0.28
SGN
1.7
SV
0.35
SV
METHYLNAPHTHALENE, 2-
91-57-6
680
SGN
1,900
SGN
1,900
SGN
NAPHTHALENE
91-20-3
25
SGN
25
SGN
25
SGN
NITROBENZENE
98-95-3
3.6
SGN
10
SGN
10
SGN
NITROPROPANE, 2-
79-46-9
0.00029
SGN
0.0015
SGN
0.0015
SGN
NITROSODIETHYLAMINE, N-
55-18-5
0.000057
SV
0.0036
SV
0.00073
SV
NITROSODIMETHYLAMINE, N-
62-75-9
0.00021
SV
0.013
SV
0.0027
SV
NITROSO-DI-N-BUTYLAMINE, N-
924-16-3
0.019
SV
0.47
SV
0.093
SV
PCB-1221 (AROCLOR)
11104-28-2
0.18
SGN
0.83
SGN
0.83
SGN
PCB-1232 (AROCLOR)
11141-16-5
0.14
SGN
0.66
SGN
0.66
SGN
PHENOL
108-95-2
570
SV
10,000
SAT
2,400
SV
PROPANOL, 2- (ISOPROPYL ALCOHOL)
67-63-0
20
SV
430
SV
86
SV
PROPYLBENZENE, N-
103-65-1
400
SGN
1,700
SGN
1,700
SGN
PROPYLENE OXIDE
75-56-9
0.053
SV
1.3
SV
0.27
SV
STYRENE
100-42-5
24
SGN
110
SV
24
SGN
TETRACHLOROETHANE, 1,1,1,2-
630-20-6
18
SGN
18
SGN
18
SGN
TETRACHLOROETHANE, 1,1,2,2-
79-34-5
0.026
SGN
0.13
SGN
0.13
SGN
TETRACHLOROETHYLENE (PCE)
127-18-4
0.43
SGN
0.43
SGN
0.43
SGN
TETRAHYDROFURAN
109-99-9
0.57
SGN
2.8
SGN
2.8
SGN
TOLUENE
108-88-3
44
SGN
44
SGN
44
SGN
TRIBROMOMETHANE (BROMOFORM)
75-25-2
3.5
SGN
3.5
SGN
3.5
SGN
TRICHLORO-1,2,2-TRIFLUOROETHANE, 1,1,2-
76-13-1
10,000
SGN
10,000
SGN
10,000
SGN

261-0300-101 / DRAFT July 25, 2015 / Page 41
Regulated Substance
CAS No.
Residential
(mg/kg)
Type
Nonresidential
(mg/kg)
Type
Converted
Residential
(mg/kg)
Type
TRICHLOROBENZENE, 1,2,4-
120-82-1
27
SGN
27
SGN
27
SGN
TRICHLOROBENZENE, 1,3,5-
108-70-3
31
SGN
31
SGN
31
SGN
TRICHLOROETHANE, 1,1,1-
71-55-6
7.2
SGN
9.5
SV
7.2
SGN
TRICHLOROETHANE, 1,1,2-
79-00-5
0.15
SGN
0.15
SGN
0.15
SGN
TRICHLOROETHYLENE (TCE)
79-01-6
0.17
SGN
0.17
SGN
0.17
SGN
TRICHLOROPROPANE, 1,2,3-
96-18-4
3.2
SGN
3.2
SGN
3.2
SGN
TRICHLOROPROPENE, 1,2,3-
96-19-5
0.037
SGN
0.15
SGN
0.15
SGN
TRIETHYLAMINE
121-44-8
0.36
SGN
1.5
SGN
1.5
SGN
TRIMETHYLBENZENE, 1,3,4-
(TRIMETHYLBENZENE, 1,2,4-)
95-63-6
8.4
SGN
35
SGN
35
SGN
TRIMETHYLBENZENE, 1,3,5-
108-67-8
74
SGN
210
SGN
210
SGN
VINYL ACETATE
108-05-4
5.0
SGN
21
SGN
21
SGN
VINYL BROMIDE (BROMOETHENE)
593-60-2
0.073
SGN
0.38
SGN
0.38
SGN
VINYL CHLORIDE
75-01-4
0.027
SGN
0.027
SGN
0.027
SGN
XYLENES (TOTAL)
1330-20-7
990
SGN
990
SGN
990
SGN
Type:
SV—calculated screening value
SGN—generic soil-to-groundwater numeric value (Title 25
Pa. Code
Ch. 250, Appendix A, Table 3B)
SAT—residual saturation limit

261-0300-101 / DRAFT July 25, 2015 / Page 42
Table 3. Near-Source Soil Gas Statewide Health Standard Vapor Intrusion Screening Values (SV
NS
)
Regulated Substance
CAS No.
Residential
(
?
g/m
3
)
Nonresidential
(
?
g/m
3
)
Converted
Residential
(
?
g/m
3
)
ACETALDEHYDE
75-07-0
1,900
39,000
7,900
ACETONE
67-64-1
6,500,000
140,000,000
27,000,000
ACETONITRILE
75-05-8
13,000
260,000
53,000
ACROLEIN
107-02-8
4.2
88
18
ACRYLAMIDE
79-06-1
19
1,200
250
ACRYLIC ACID
79-10-7
210
4,400
880
ACRYLONITRILE
107-13-1
72
1,800
360
ALLYL ALCOHOL
107-18-6
21
440
88
AMMONIA
7664-41-7
21,000
440,000
88,000
ANILINE
62-53-3
210
4,400
880
BENZENE
71-43-2
620
16,000
3,100
BENZYL CHLORIDE
100-44-7
99
2,500
500
BETA PROPIOLACTONE
57-57-8
1.2
31
6.1
BIPHENYL, 1,1-
92-52-4
83
1,800
350
BIS(2-CHLOROETHYL)ETHER
111-44-4
15
370
74
BIS(2-CHLORO-ISOPROPYL)ETHER
108-60-1
490
12,000
2,500
BIS(CHLOROMETHYL)ETHER
542-88-1
0.079
2.0
0.40
BROMOCHLOROMETHANE
74-97-5
8,300
180,000
35,000
BROMODICHLOROMETHANE
75-27-4
130
3,300
660
BROMOMETHANE
74-83-9
1,000
22,000
4,400
BUTADIENE, 1,3-
106-99-0
160
4,100
820
CARBON DISULFIDE
75-15-0
150,000
3,100,000
610,000
CARBON TETRACHLORIDE
56-23-5
810
20,000
4,100
CHLORO-1,1-DIFLUOROETHANE, 1-
75-68-3
10,000,000
220,000,000
44,000,000
CHLORO-1-PROPENE, 3- (ALLYL CHLORIDE)
107-05-1
210
4,400
880
CHLOROBENZENE
108-90-7
10,000
220,000
44,000
CHLORODIBROMOMETHANE
124-48-1
180
4,500
910
CHLORODIFLUOROMETHANE
75-45-6
10,000,000
220,000,000
44,000,000
CHLOROETHANE
75-00-3
2,100,000
44,000,000
8,800,000
CHLOROFORM
67-66-3
210
5,300
1,100
CHLOROPRENE
126-99-8
16
410
82
CHLOROPROPANE, 2-
75-29-6
21,000
440,000
88,000
CRESOL(S)
1319-77-3
130,000
2,600,000
530,000

261-0300-101 / DRAFT July 25, 2015 / Page 43
Regulated Substance
CAS No.
Residential
(
?
g/m
3
)
Nonresidential
(
?
g/m
3
)
Converted
Residential
(
?
g/m
3
)
CUMENE (ISOPROPYL BENZENE)
98-82-8
83,000
1,800,000
350,000
CYCLOHEXANE
110-82-7
1,300,000
26,000,000
5,300,000
CYCLOHEXANONE
108-94-1
150,000
3,100,000
610,000
DIBROMO-3-CHLOROPROPANE, 1,2-
96-12-8
0.32
20
4.1
DIBROMOETHANE, 1,2- (ETHYLENE DIBROMIDE)
106-93-4
8.1
200
41
DIBROMOMETHANE
74-95-3
830
18,000
3,500
DICHLORO-2-BUTENE, 1,4-
764-41-0
1.2
29
5.8
DICHLORO-2-BUTENE, TRANS-1,4-
110-57-6
1.2
29
5.8
DICHLOROBENZENE, 1,2-
95-50-1
42,000
880,000
180,000
DICHLOROBENZENE, P-
106-46-7
440
11,000
2,200
DICHLORODIFLUOROMETHANE (FREON 12)
75-71-8
21,000
440,000
88,000
DICHLOROETHANE, 1,1-
75-34-3
3,000
77,000
15,000
DICHLOROETHANE, 1,2-
107-06-2
190
4,700
940
DICHLOROETHYLENE, 1,1-
75-35-4
42,000
880,000
180,000
DICHLOROETHYLENE, TRANS-1,2-
156-60-5
13,000
260,000
53,000
DICHLOROMETHANE (METHYLENE CHLORIDE)
75-09-2
130,000
2,600,000
530,000
DICHLOROPROPANE, 1,2-
78-87-5
490
12,000
2,500
DICHLOROPROPENE, 1,3-
542-75-6
1,200
31,000
6,100
DICYCLOPENTADIENE
77-73-6
63
1,300
260
DIOXANE, 1,4-
123-91-1
630
16,000
3,200
EPICHLOROHYDRIN
106-89-8
210
4,400
880
ETHOXYETHANOL, 2- (EGEE)
110-80-5
42,000
880,000
180,000
ETHYL ACETATE
141-78-6
15,000
310,000
61,000
ETHYL ACRYLATE
140-88-5
1,700
35,000
7,000
ETHYL BENZENE
100-41-4
1,900
49,000
9,800
ETHYL METHACRYLATE
97-63-2
63,000
1,300,000
260,000
ETHYLENE GLYCOL
107-21-1
83,000
1,800,000
350,000
FLUOROTRICHLOROMETHANE (FREON 11)
75-69-4
150,000
3,100,000
610,000
FORMALDEHYDE
50-00-0
370
9,400
1,900
FORMIC ACID
64-18-6
63
1,300
260
FURFURAL
98-01-1
10,000
220,000
44,000
HEXACHLOROETHANE
67-72-1
490
12,000
2,500
HEXANE
110-54-3
150,000
3,100,000
610,000
HYDRAZINE/HYDRAZINE SULFATE
302-01-2
1.0
25
5.0
METHACRYLONITRILE
126-98-7
6,300
130,000
26,000

261-0300-101 / DRAFT July 25, 2015 / Page 44
Regulated Substance
CAS No.
Residential
(
?
g/m
3
)
Nonresidential
(
?
g/m
3
)
Converted
Residential
(
?
g/m
3
)
METHANOL
67-56-1
830,000
18,000,000
3,500,000
METHOXYETHANOL, 2-
109-86-4
4,200
88,000
18,000
METHYL ACRYLATE
96-33-3
4,200
88,000
18,000
METHYL CHLORIDE
74-87-3
2,700
68,000
14,000
METHYL ETHYL KETONE
78-93-3
1,000,000
22,000,000
4,400,000
METHYL HYDRAZINE
60-34-4
4.2
88
18
METHYL ISOBUTYL KETONE
108-10-1
630,000
13,000,000
2,600,000
METHYL ISOCYANATE
624-83-9
210
4,400
880
METHYL METHACRYLATE
80-62-6
150,000
3,100,000
610,000
METHYL N-BUTYL KETONE (2-HEXANONE)
591-78-6
6,300
130,000
26,000
METHYL STYRENE (MIXED ISOMERS)
25013-15-4
8,300
180,000
35,000
METHYL TERT-BUTYL ETHER (MTBE)
1634-04-4
19,000
470,000
94,000
METHYLNAPHTHALENE, 2-
91-57-6
630
13,000
2,600
NAPHTHALENE
91-20-3
140
3,600
720
NITROBENZENE
98-95-3
120
3,100
610
NITROPROPANE, 2-
79-46-9
1.8
45
9.1
NITROSODIETHYLAMINE, N-
55-18-5
0.045
2.9
0.57
NITROSODIMETHYLAMINE, N-
62-75-9
0.14
8.8
1.8
NITROSO-DI-N-BUTYLAMINE, N-
924-16-3
3.0
77
15
PCB-1221 (AROCLOR)
11104-28-2
8.5
220
43
PCB-1232 (AROCLOR)
11141-16-5
8.5
220
43
PHENOL
108-95-2
42,000
880,000
180,000
PROPANOL, 2- (ISOPROPYL ALCOHOL)
67-63-0
42,000
880,000
180,000
PROPYLBENZENE, N-
103-65-1
210,000
4,400,000
880,000
PROPYLENE OXIDE
75-56-9
1,300
33,000
6,600
STYRENE
100-42-5
210,000
4,400,000
880,000
TETRACHLOROETHANE, 1,1,1,2-
630-20-6
660
17,000
3,300
TETRACHLOROETHANE, 1,1,2,2-
79-34-5
84
2,100
420
TETRACHLOROETHYLENE (PCE)
127-18-4
8,300
180,000
35,000
TETRAHYDROFURAN
109-99-9
2,500
63,000
13,000
TOLUENE
108-88-3
1,000,000
22,000,000
4,400,000
TRIBROMOMETHANE (BROMOFORM)
75-25-2
4,400
110,000
22,000
TRICHLORO-1,2,2-TRIFLUOROETHANE, 1,1,2-
76-13-1
6,300,000
130,000,000
26,000,000
TRICHLOROBENZENE, 1,2,4-
120-82-1
420
8,800
1,800
TRICHLOROBENZENE, 1,3,5-
108-70-3
420
8,800
1,800

261-0300-101 / DRAFT July 25, 2015 / Page 45
Regulated Substance
CAS No.
Residential
(
?
g/m
3
)
Nonresidential
(
?
g/m
3
)
Converted
Residential
(
?
g/m
3
)
TRICHLOROETHANE, 1,1,1-
71-55-6
1,000,000
22,000,000
4,400,000
TRICHLOROETHANE, 1,1,2-
79-00-5
42
880
180
TRICHLOROETHYLENE (TCE)
79-01-6
420
8,800
1,800
TRICHLOROPROPANE, 1,2,3-
96-18-4
63
1,300
260
TRICHLOROPROPENE, 1,2,3-
96-19-5
63
1,300
260
TRIETHYLAMINE
121-44-8
1,500
31,000
6,100
TRIMETHYLBENZENE, 1,3,4- (TRIMETHYLBENZENE, 1,2,4-)
95-63-6
1,500
31,000
6,100
TRIMETHYLBENZENE, 1,3,5-
108-67-8
1,500
31,000
6,100
VINYL ACETATE
108-05-4
42,000
880,000
180,000
VINYL BROMIDE (BROMOETHENE)
593-60-2
150
3,800
770
VINYL CHLORIDE
75-01-4
160
14,000
2,700
XYLENES (TOTAL)
1330-20-7
21,000
440,000
88,000

261-0300-101 / DRAFT July 25, 2015 / Page 46
Table 4. Sub-Slab Soil Gas Statewide Health Standard Vapor Intrusion Screening Values (SV
SS
)
Regulated Substance
CAS No.
Residential
(
?
g/m
3
)
?
Nonresidential
(
?
g/m
3
)
Converted
Residential
(
?
g/m
3
)
ACETALDEHYDE
75-07-0
360
5,100
1,500
ACETONE
67-64-1
1,200,000
17,000,000
5,200,000
ACETONITRILE
75-05-8
2,400
34,000
10,000
ACROLEIN
107-02-8
0.80
11
3.4
ACRYLAMIDE
79-06-1
3.7
160
47
ACRYLIC ACID
79-10-7
40
560
170
ACRYLONITRILE
107-13-1
14
230
69
ALLYL ALCOHOL
107-18-6
4.0
56
17
AMMONIA
7664-41-7
4,000
56,000
17,000
ANILINE
62-53-3
40
560
170
BENZENE
71-43-2
120
2,000
610
BENZYL CHLORIDE
100-44-7
19
320
96
BETA PROPIOLACTONE
57-57-8
0.23
3.9
1.2
BIPHENYL, 1,1-
92-52-4
16
220
67
BIS(2-CHLOROETHYL)ETHER
111-44-4
2.8
48
14
BIS(2-CHLORO-ISOPROPYL)ETHER
108-60-1
94
1,600
470
BIS(CHLOROMETHYL)ETHER
542-88-1
0.015
0.25
0.076
BROMOCHLOROMETHANE
74-97-5
1,600
22,000
6,700
BROMODICHLOROMETHANE
75-27-4
25
430
130
BROMOMETHANE
74-83-9
200
2,800
840
BUTADIENE, 1,3-
106-99-0
31
520
160
CARBON DISULFIDE
75-15-0
28,000
390,000
120,000
CARBON TETRACHLORIDE
56-23-5
160
2,600
790
CHLORO-1,1-DIFLUOROETHANE, 1-
75-68-3
2,000,000
28,000,000
8,400,000
CHLORO-1-PROPENE, 3- (ALLYL CHLORIDE)
107-05-1
40
560
170
CHLOROBENZENE
108-90-7
2,000
28,000
8,400
CHLORODIBROMOMETHANE
124-48-1
35
580
170
CHLORODIFLUOROMETHANE
75-45-6
2,000,000
28,000,000
8,400,000
CHLOROETHANE
75-00-3
400,000
5,600,000
1,700,000
CHLOROFORM
67-66-3
41
680
210
CHLOROPRENE
126-99-8
3.1
52
16
CHLOROPROPANE, 2-
75-29-6
4,000
56,000
17,000
CRESOL(S)
1319-77-3
24,000
340,000
100,000

261-0300-101 / DRAFT July 25, 2015 / Page 47
Regulated Substance
CAS No.
Residential
(
?
g/m
3
)
?
Nonresidential
(
?
g/m
3
)
Converted
Residential
(
?
g/m
3
)
CUMENE (ISOPROPYL BENZENE)
98-82-8
16,000
220,000
67,000
CYCLOHEXANE
110-82-7
240,000
3,400,000
1,000,000
CYCLOHEXANONE
108-94-1
28,000
390,000
120,000
DIBROMO-3-CHLOROPROPANE, 1,2-
96-12-8
0.062
2.6
0.79
DIBROMOETHANE, 1,2- (ETHYLENE DIBROMIDE)
106-93-4
1.6
26
7.9
DIBROMOMETHANE
74-95-3
160
2,200
670
DICHLORO-2-BUTENE, 1,4-
764-41-0
0.22
3.7
1.1
DICHLORO-2-BUTENE, TRANS-1,4-
110-57-6
0.22
3.7
1.1
DICHLOROBENZENE, 1,2-
95-50-1
8,000
110,000
34,000
DICHLOROBENZENE, P-
106-46-7
85
1,400
430
DICHLORODIFLUOROMETHANE (FREON 12)
75-71-8
4,000
56,000
17,000
DICHLOROETHANE, 1,1-
75-34-3
590
9,800
3,000
DICHLOROETHANE, 1,2-
107-06-2
36
610
180
DICHLOROETHYLENE, 1,1-
75-35-4
8,000
110,000
34,000
DICHLOROETHYLENE, TRANS-1,2-
156-60-5
2,400
34,000
10,000
DICHLOROMETHANE (METHYLENE CHLORIDE)
75-09-2
24,000
340,000
100,000
DICHLOROPROPANE, 1,2-
78-87-5
94
1,600
470
DICHLOROPROPENE, 1,3-
542-75-6
230
3,900
1,200
DICYCLOPENTADIENE
77-73-6
12
170
51
DIOXANE, 1,4-
123-91-1
120
2,000
610
EPICHLOROHYDRIN
106-89-8
40
560
170
ETHOXYETHANOL, 2- (EGEE)
110-80-5
8,000
110,000
34,000
ETHYL ACETATE
141-78-6
2,800
39,000
12,000
ETHYL ACRYLATE
140-88-5
320
4,500
1,300
ETHYL BENZENE
100-41-4
370
6,300
1,900
ETHYL METHACRYLATE
97-63-2
12,000
170,000
51,000
ETHYLENE GLYCOL
107-21-1
16,000
220,000
67,000
FLUOROTRICHLOROMETHANE (FREON 11)
75-69-4
28,000
390,000
120,000
FORMALDEHYDE
50-00-0
72
1,200
360
FORMIC ACID
64-18-6
12
170
51
FURFURAL
98-01-1
2,000
28,000
8,400
HEXACHLOROETHANE
67-72-1
94
1,600
470
HEXANE
110-54-3
28,000
390,000
120,000
HYDRAZINE/HYDRAZINE SULFATE
302-01-2
0.19
3.2
1.0
METHACRYLONITRILE
126-98-7
1,200
17,000
5,100

261-0300-101 / DRAFT July 25, 2015 / Page 48
Regulated Substance
CAS No.
Residential
(
?
g/m
3
)
?
Nonresidential
(
?
g/m
3
)
Converted
Residential
(
?
g/m
3
)
METHANOL
67-56-1
160,000
2,200,000
670,000
METHOXYETHANOL, 2-
109-86-4
800
11,000
3,400
METHYL ACRYLATE
96-33-3
800
11,000
3,400
METHYL CHLORIDE
74-87-3
520
8,700
2,600
METHYL ETHYL KETONE
78-93-3
200,000
2,800,000
840,000
METHYL HYDRAZINE
60-34-4
0.80
11
3.4
METHYL ISOBUTYL KETONE
108-10-1
120,000
1,700,000
510,000
METHYL ISOCYANATE
624-83-9
40
560
170
METHYL METHACRYLATE
80-62-6
28,000
390,000
120,000
METHYL N-BUTYL KETONE (2-HEXANONE)
591-78-6
1,200
17,000
5,100
METHYL STYRENE (MIXED ISOMERS)
25013-15-4
1,600
22,000
6,700
METHYL TERT-BUTYL ETHER (MTBE)
1634-04-4
3,600
61,000
18,000
METHYLNAPHTHALENE, 2-
91-57-6
120
1,700
510
NAPHTHALENE
91-20-3
28
460
140
NITROBENZENE
98-95-3
23
390
120
NITROPROPANE, 2-
79-46-9
0.35
5.8
1.7
NITROSODIETHYLAMINE, N-
55-18-5
0.0086
0.37
0.11
NITROSODIMETHYLAMINE, N-
62-75-9
0.026
1.1
0.34
NITROSO-DI-N-BUTYLAMINE, N-
924-16-3
0.59
10
3.0
PCB-1221 (AROCLOR)
11104-28-2
1.6
28
8.3
PCB-1232 (AROCLOR)
11141-16-5
1.6
28
8.3
PHENOL
108-95-2
8,000
110,000
34,000
PROPANOL, 2- (ISOPROPYL ALCOHOL)
67-63-0
8,000
110,000
34,000
PROPYLBENZENE, N-
103-65-1
40,000
560,000
170,000
PROPYLENE OXIDE
75-56-9
250
4,300
1,300
STYRENE
100-42-5
40,000
560,000
170,000
TETRACHLOROETHANE, 1,1,1,2-
630-20-6
130
2,100
640
TETRACHLOROETHANE, 1,1,2,2-
79-34-5
16
270
81
TETRACHLOROETHYLENE (PCE)
127-18-4
1,600
22,000
6,700
TETRAHYDROFURAN
109-99-9
480
8,100
2,400
TOLUENE
108-88-3
200,000
2,800,000
840,000
TRIBROMOMETHANE (BROMOFORM)
75-25-2
850
14,000
4,300
TRICHLORO-1,2,2-TRIFLUOROETHANE, 1,1,2-
76-13-1
1,200,000
17,000,000
5,100,000
TRICHLOROBENZENE, 1,2,4-
120-82-1
80
1,100
340
TRICHLOROBENZENE, 1,3,5-
108-70-3
80
1,100
340

261-0300-101 / DRAFT July 25, 2015 / Page 49
Regulated Substance
CAS No.
Residential
(
?
g/m
3
)
?
Nonresidential
(
?
g/m
3
)
Converted
Residential
(
?
g/m
3
)
TRICHLOROETHANE, 1,1,1-
71-55-6
200,000
2,800,000
840,000
TRICHLOROETHANE, 1,1,2-
79-00-5
8.0
110
34
TRICHLOROETHYLENE (TCE)
79-01-6
80
1,100
340
TRICHLOROPROPANE, 1,2,3-
96-18-4
12
170
51
TRICHLOROPROPENE, 1,2,3-
96-19-5
12
170
51
TRIETHYLAMINE
121-44-8
280
3,900
1,200
TRIMETHYLBENZENE, 1,3,4- (TRIMETHYLBENZENE, 1,2,4-)
95-63-6
280
3,900
1,200
TRIMETHYLBENZENE, 1,3,5-
108-67-8
280
3,900
1,200
VINYL ACETATE
108-05-4
8,000
110,000
34,000
VINYL BROMIDE (BROMOETHENE)
593-60-2
29
490
150
VINYL CHLORIDE
75-01-4
30
1,700
520
XYLENES (TOTAL)
1330-20-7
4,000
56,000
17,000

261-0300-101 / DRAFT July 25, 2015 / Page 50
Table 5. Indoor Air Statewide Health Standard Vapor Intrusion Screening Values (SV
IA
)
Regulated Substance
CAS No.
Residential
(
?
g/m
3
)
?
Nonresidential
(
?
g/m
3
)
?
ACETALDEHYDE
75-07-0
9.4
39
ACETONE
67-64-1
32,000
140,000
ACETONITRILE
75-05-8
63
260
ACROLEIN
107-02-8
0.021
0.088
ACRYLAMIDE
79-06-1
0.096
1.2
ACRYLIC ACID
79-10-7
1.0
4.4
ACRYLONITRILE
107-13-1
0.36
1.8
ALLYL ALCOHOL
107-18-6
0.10
0.44
AMMONIA
7664-41-7
100
440
ANILINE
62-53-3
1.0
4.4
BENZENE
71-43-2
3.1
16
BENZYL CHLORIDE
100-44-7
0.50
2.5
BETA PROPIOLACTONE
57-57-8
0.0061
0.031
BIPHENYL, 1,1-
92-52-4
0.42
1.8
BIS(2-CHLOROETHYL)ETHER
111-44-4
0.074
0.37
BIS(2-CHLORO-ISOPROPYL)ETHER
108-60-1
2.4
12
BIS(CHLOROMETHYL)ETHER
542-88-1
0.00039
0.0020
BROMOCHLOROMETHANE
74-97-5
42
180
BROMODICHLOROMETHANE
75-27-4
0.66
3.3
BROMOMETHANE
74-83-9
5.2
22
BUTADIENE, 1,3-
106-99-0
0.81
4.1
CARBON DISULFIDE
75-15-0
730
3,100
CARBON TETRACHLORIDE
56-23-5
4.1
20
CHLORO-1,1-DIFLUOROETHANE, 1-
75-68-3
52,000
220,000
CHLORO-1-PROPENE, 3- (ALLYL CHLORIDE)
107-05-1
1.0
4.4
CHLOROBENZENE
108-90-7
52
220
CHLORODIBROMOMETHANE
124-48-1
0.90
4.5
CHLORODIFLUOROMETHANE
75-45-6
52,000
220,000
CHLOROETHANE
75-00-3
10,000
44,000
CHLOROFORM
67-66-3
1.1
5.3
CHLOROPRENE
126-99-8
0.081
0.41
CHLOROPROPANE, 2-
75-29-6
100
440
CRESOL(S)
1319-77-3
630
2,600
CUMENE (ISOPROPYL BENZENE)
98-82-8
420
1,800

261-0300-101 / DRAFT July 25, 2015 / Page 51
Regulated Substance
CAS No.
Residential
(
?
g/m
3
)
?
Nonresidential
(
?
g/m
3
)
?
CYCLOHEXANE
110-82-7
6,300
26,000
CYCLOHEXANONE
108-94-1
730
3,100
DIBROMO-3-CHLOROPROPANE, 1,2-
96-12-8
0.0016
0.020
DIBROMOETHANE, 1,2- (ETHYLENE DIBROMIDE)
106-93-4
0.041
0.20
DIBROMOMETHANE
74-95-3
4.2
18
DICHLORO-2-BUTENE, 1,4-
764-41-0
0.0058
0.029
DICHLORO-2-BUTENE, TRANS-1,4-
110-57-6
0.0058
0.029
DICHLOROBENZENE, 1,2-
95-50-1
210
880
DICHLOROBENZENE, P-
106-46-7
2.2
11
DICHLORODIFLUOROMETHANE (FREON 12)
75-71-8
100
440
DICHLOROETHANE, 1,1-
75-34-3
15
77
DICHLOROETHANE, 1,2-
107-06-2
0.94
4.7
DICHLOROETHYLENE, 1,1-
75-35-4
210
880
DICHLOROETHYLENE, TRANS-1,2-
156-60-5
63
260
DICHLOROMETHANE (METHYLENE CHLORIDE)
75-09-2
630
2,600
DICHLOROPROPANE, 1,2-
78-87-5
2.4
12
DICHLOROPROPENE, 1,3-
542-75-6
6.1
31
DICYCLOPENTADIENE
77-73-6
0.31
1.3
DIOXANE, 1,4-
123-91-1
3.2
16
EPICHLOROHYDRIN
106-89-8
1.0
4.4
ETHOXYETHANOL, 2- (EGEE)
110-80-5
210
880
ETHYL ACETATE
141-78-6
73
310
ETHYL ACRYLATE
140-88-5
8.3
35
ETHYL BENZENE
100-41-4
9.7
49
ETHYL METHACRYLATE
97-63-2
310
1,300
ETHYLENE GLYCOL
107-21-1
420
1,800
FLUOROTRICHLOROMETHANE (FREON 11)
75-69-4
730
3,100
FORMALDEHYDE
50-00-0
1.9
9.4
FORMIC ACID
64-18-6
0.31
1.3
FURFURAL
98-01-1
52
220
HEXACHLOROETHANE
67-72-1
2.4
12
HEXANE
110-54-3
730
3,100
HYDRAZINE/HYDRAZINE SULFATE
302-01-2
0.0050
0.025
METHACRYLONITRILE
126-98-7
31
130
METHANOL
67-56-1
4,200
18,000
METHOXYETHANOL, 2-
109-86-4
21
88

261-0300-101 / DRAFT July 25, 2015 / Page 52
Regulated Substance
CAS No.
Residential
(
?
g/m
3
)
?
Nonresidential
(
?
g/m
3
)
?
METHYL ACRYLATE
96-33-3
21
88
METHYL CHLORIDE
74-87-3
14
68
METHYL ETHYL KETONE
78-93-3
5,200
22,000
METHYL HYDRAZINE
60-34-4
0.021
0.088
METHYL ISOBUTYL KETONE
108-10-1
3,100
13,000
METHYL ISOCYANATE
624-83-9
1.0
4.4
METHYL METHACRYLATE
80-62-6
730
3,100
METHYL N-BUTYL KETONE (2-HEXANONE)
591-78-6
31
130
METHYL STYRENE (MIXED ISOMERS)
25013-15-4
42
180
METHYL TERT-BUTYL ETHER (MTBE)
1634-04-4
94
470
METHYLNAPHTHALENE, 2-
91-57-6
3.1
13
NAPHTHALENE
91-20-3
0.72
3.6
NITROBENZENE
98-95-3
0.61
3.1
NITROPROPANE, 2-
79-46-9
0.0090
0.045
NITROSODIETHYLAMINE, N-
55-18-5
0.00022
0.0029
NITROSODIMETHYLAMINE, N-
62-75-9
0.00069
0.0088
NITROSO-DI-N-BUTYLAMINE, N-
924-16-3
0.015
0.077
PCB-1221 (AROCLOR)
11104-28-2
0.043
0.22
PCB-1232 (AROCLOR)
11141-16-5
0.043
0.22
PHENOL
108-95-2
210
880
PROPANOL, 2- (ISOPROPYL ALCOHOL)
67-63-0
210
880
PROPYLBENZENE, N-
103-65-1
1,000
4,400
PROPYLENE OXIDE
75-56-9
6.6
33
STYRENE
100-42-5
1,000
4,400
TETRACHLOROETHANE, 1,1,1,2-
630-20-6
3.3
17
TETRACHLOROETHANE, 1,1,2,2-
79-34-5
0.42
2.1
TETRACHLOROETHYLENE (PCE)
127-18-4
42
180
TETRAHYDROFURAN
109-99-9
13
63
TOLUENE
108-88-3
5,200
22,000
TRIBROMOMETHANE (BROMOFORM)
75-25-2
22
110
TRICHLORO-1,2,2-TRIFLUOROETHANE, 1,1,2-
76-13-1
31,000
130,000
TRICHLOROBENZENE, 1,2,4-
120-82-1
2.1
8.8
TRICHLOROBENZENE, 1,3,5-
108-70-3
2.1
8.8
TRICHLOROETHANE, 1,1,1-
71-55-6
5,200
22,000
TRICHLOROETHANE, 1,1,2-
79-00-5
0.21
0.88
TRICHLOROETHYLENE (TCE)
79-01-6
2.1
8.8

261-0300-101 / DRAFT July 25, 2015 / Page 53
Regulated Substance
CAS No.
Residential
(
?
g/m
3
)
?
Nonresidential
(
?
g/m
3
)
?
TRICHLOROPROPANE, 1,2,3-
96-18-4
0.31
1.3
TRICHLOROPROPENE, 1,2,3-
96-19-5
0.31
1.3
TRIETHYLAMINE
121-44-8
7.3
31
TRIMETHYLBENZENE, 1,3,4- (TRIMETHYLBENZENE, 1,2,4-)
95-63-6
7.3
31
TRIMETHYLBENZENE, 1,3,5-
108-67-8
7.3
31
VINYL ACETATE
108-05-4
210
880
VINYL BROMIDE (BROMOETHENE)
593-60-2
0.76
3.8
VINYL CHLORIDE
75-01-4
0.79
14
XYLENES (TOTAL)
1330-20-7
100
440

261-0300-101 / DRAFT July 25, 2015 / Page 54
Table 6. Collection of Data for Vapor Intrusion Screening
Sample
Conditions for VI Data Collection
Soil
• Collect an appropriate number of samples to characterize the source(s) and/or
demonstrate attainment.
• The samples are from unsaturated soil.
• No SPL is present.
Groundwater • Install an appropriate number of monitoring wells to characterize the source(s) and/or
demonstrate attainment.
• Sample from properly constructed monitoring wells.
• Monitoring well screens cross the water table.
• The wetted length of the well screen should be no more than 10 feet. (Alternative
methods such as using a packer to sample across the water table in deeper bedrock
well may be acceptable.)
• Contaminated groundwater that exceeds screening values cannot be in contact with the
building foundation.
• Acceptable soil or soil-like material exists between the water table and the building
foundation.
• No SPL is present.
Near-Source
Soil Gas
• Account for potential spatial variability in the sampling design based on the soil and
groundwater data.
• Collect at least two rounds of samples from at least two locations.
• Locate sample points where they will be most representative of soil gas in Potential VI
Sources and preferential pathways (if applicable).
• The sample depth is within about 1 foot of the top of the capillary fringe for
groundwater sources, considering the effects of water table fluctuations.
• Sample above bedrock when the water table is within bedrock.
• Sample within or no more than 1 foot above vadose zone soil sources.
• Sample at least 5 feet below grade.
• Acceptable soil or soil-like material exists between the source and the building
foundation.
• Refer to Appendix Z.
Sub-Slab
Soil Gas
• Account for potential spatial variability in the sampling design.
• Collect at least two rounds of samples from at least two locations.
• Bias sample points towards areas of greatest expected impact.
• Refer to Appendix Z.
Indoor Air
• Account for potential spatial variability in the sampling design.
• Collect at least two rounds of samples from at least two locations.
• Sample in the lowest occupied floor (basement and/or first floor).
• Sample when the daily average outdoor temperature is at least 15°F below the
minimum indoor temperature of the occupied space.
• Refer to Appendix Z.

261-0300-101 / DRAFT July 25, 2015 / Page 55
Table 7. Application of Statewide Health Standard Vapor Intrusion Screening Criteria
Characterization Data
Vapor Intrusion Screening Conditions
Soil Characterization
• Soil attains the Statewide health standard on the basis of the
characterization data without remediation.
• Use all applicable soil characterization data for VI screening.
• If there are no exceedances of VI soil screening values (SV
SOIL
), then
the VI evaluation is complete.
Groundwater
Characterization
• Groundwater attains the Statewide health standard on the basis of the
characterization data without remediation.
• Use all applicable groundwater characterization data for VI screening.
• Collect at least two rounds of data.
• If there are no exceedances of vapor intrusion groundwater screening
values (SV
GW
), then the VI evaluation is complete.
Near-Source Soil Gas,
Sub-Slab Soil Gas, or
Indoor Air
Characterization
• The remediator may characterize and screen soil gas or indoor air with
a limited number of sampling rounds.
• Sample at least two locations and perform a minimum of two sampling
events.
• Collect samples at least 45 days apart.
• If there are no exceedances of VI screening values (SV
NS
, SV
SS
, SV
IA
),
then the VI evaluation is complete.
Attainment Data
Vapor Intrusion Screening Conditions
Soil Attainment
• Use all applicable soil attainment data.
• The attainment requirements for soil in Sections 250.702, 250.703,
and 250.707(b)(1) may be utilized for vapor intrusion soil screening
(e.g., 75%/10x rule).
Groundwater Attainment
• Use all applicable groundwater attainment data.
• When eight or more consecutive quarters of data are available then the
attainment requirements for groundwater in Sections 250.702, 250.704,
and 250.707(b)(2)(i) may be utilized for vapor intrusion groundwater
screening (e.g., 75%/10x rule on the property and 75%/2x rule beyond
the property boundary).
• Fewer than eight rounds of data may be screened with DEP approval
pursuant to Section 250.704(d). The VI evaluation is complete if all
concentrations are less than or equal to the groundwater screening
values (SV
GW
).
• The alternate groundwater attainment statistical method of
Section 250.707(b)(2)(ii) may be applied to VI screening when the
minimum number of samples specified by the documentation of the
method have been collected.

261-0300-101 / DRAFT July 25, 2015 / Page 56
Table 7. Application of Statewide Health Standard Vapor Intrusion Screening Criteria
(Continued)
VI Monitoring Data
Vapor Intrusion Screening Conditions
Near-Source Soil Gas,
Sub-Slab Soil Gas, or
Indoor Air Monitoring
• Soil gas and indoor air monitoring is performed on a quarterly basis or
twice per quarter with samples collected at least 45 days apart.
• The Department may approve alternative sampling frequencies.
• Near-source and sub-slab soil gas samples are collected from all of the
same probes in each event.
• Indoor air samples are collected at all of the same locations in each
event.
• There are a minimum of two sampling rounds.
• Statistical tests for screening are applied to the collective data from all
near-source soil gas, sub-slab soil gas, or indoor air locations and
rounds at each building or portion of a building with a potential VI
impact.
• Statistical tests may be used when there is a combination of at least
eight sample locations and sampling rounds of any given type (near
source soil gas, sub-slab soil gas, or indoor air) at each current or
potential future building.
• The following statistical test may be applied when screening VI data:
Seventy-five percent of all samples are equal to or less than the
applicable screening value with no individual sample exceeding ten
times the screening value on the property (75%/10x rule) and two
times the screening value beyond the property boundary (75%/2x rule).
• An alternative statistical method may be applied to VI screening when
the minimum number of samples specified by the documentation of the
method have been collected:
As applied in accordance with EPA approved statistical methods, the
95% UCL of the arithmetic mean is at or below the applicable
screening value.

261-0300-101 / DRAFT July 25, 2015 / Page 57
L.
References
American Petroleum Institute (API), 2005, Collecting and Interpreting Soil Gas Samples from
the Vadose Zone, Publication No. 4741, Washington, DC.
American Petroleum Institute (API), 2010,
BioVapor User’s Manual
, Washington, DC.
American Society for Testing and Materials (ASTM), 2007a, Standard Test Method for Particle-
Size Analysis of Soils, D422-63(2007)e2, West Conshohocken, PA.
American Society for Testing and Materials (ASTM), 2007b, Standard Guide for Assessing
Depressurization-Induced Backdrafting and Spillage from Vented Combustion
Appliances, E1998-11, West Conshohocken, PA.
American Society for Testing and Materials (ASTM), 2008, Standard Practice for Radon Control
Options for the Design and Construction of New Low-rise Residential Buildings,
E1465-08a, West Conshohocken, PA.
American Society for Testing and Materials (ASTM), 2009a, Standard Test Methods for
Laboratory Determination of Density (Unit Weight) of Soil Specimens, D7263-09, West
Conshohocken, PA.
American Society for Testing and Materials (ASTM), 2009b, Standard Practice for Installing
Radon Mitigation Systems in Existing Low-Rise Residential Buildings, E2121-13, West
Conshohocken, PA.
American Society for Testing and Materials (ASTM), 2010a, Standard Test Method for Density
of Soil in Place by the Drive-Cylinder Method, D2937-10, West Conshohocken, PA.
American Society for Testing and Materials (ASTM), 2010b, Standard Test Methods for
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Conshohocken, PA.
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dilute chlorinated solvent groundwater plume,
Environmental Science & Technology
, 47,
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gas concentrations near and beneath a building overlying shallow petroleum
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Installation, and Operation of Sub-slab Depressurization Systems.

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in VOC concentrations at vapor intrusion investigation sites, in Proceedings of Air &
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September 26–28, Providence, RI, 129–142.
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the State of New York, Troy, NY.
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Pennsylvania Radon
Mitigation Standards
, Bureau of Radiation Protection, Harrisburg, PA, 294-2309-002.
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Quick Domenico Groundwater Fate-and-Transport Model
, Bureau of Environmental
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, 9,
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intrusion from the vadose zone—seven algorithms compared,
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Low Permeability Fill Material – Design and Installation of a Home Radon Reduction
System, EPA/625/6-91/029.
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Detached Houses – Technical Guidance (Third Edition) for Active Soil Depressurization
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Guide on how to build Radon-Resistant Homes, Office of Air and Radiation,
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, National Center for Environmental Assessment, Washington, DC,
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Regional Screening Levels for Chemical
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, Mid-Atlantic Hazardous Sites Cleanup,
Philadelphia, PA.
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Calculator, User’s Guide
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Washington, DC.
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Environmental Science & Technology
, 45, 2227-2235.

261-0300-101 / DRAFT July 25, 2015 / Page 62

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APPENDICES

261-0300-101 / DRAFT July 25, 2015 / Page 63
Appendix X: Methodology for Developing Statewide Health Standard Vapor Intrusion Screening
Values
DEP has calculated VI screening values (SVs) for use with the Statewide health standard. These SVs
may be applied to appropriately collected data for indoor air, sub-slab soil gas, near-source soil gas, soil,
and groundwater. The methods used to develop the SVs are explained in the following sections.
The SVs for subsurface media are derived using attenuation factors (?). An attenuation factor is the
ratio between the contaminant concentration in indoor air and the equilibrium soil gas concentration in
the medium (? ≡
C
IA
/
C
SG
).
DEP’s approach is to first calculate indoor air SVs (SV
IA
), then to determine sub-slab soil gas, near-
source soil gas, soil, and groundwater SVs based on attenuation factors established for each of those
media.
As there are distinct attenuation factors for residential (?
R
) and nonresidential (?
NR
) structures, DEP
carries out separate calculations for SVs that apply to buildings constructed for residential use that have
been converted to a purely nonresidential use. These attenuation factors (?
CR
) are equal to the
residential factors under the assumption that vapor flow rates and indoor air exchange rates are
comparable to residential structures. The converted residential SVs are derived from the nonresidential
indoor air SVs.
The VI screening values are provided in Tables VI-1 through VI-5 of the VI Guidance. They will be
updated periodically using current scientific information when Chapter 250 MSCs are revised,
consistent with Section 250.11.
1.
Indoor Air
Indoor air represents the point of exposure for inhalation of volatile chemicals in the VI pathway.
The POA for indoor air screening is the basement or lowest occupied level of the building.
Contaminants that pose a risk for VI either have a boiling point less than 200°C or a Henry’s law
constant greater than or equal to 1 x 10
–5
atm-m
3
/mol and a molecular weight less than
200 g/mol. Certain regulated substances meet these criteria but currently have no inhalation
toxicity values; they are listed in Table X-1. DEP has not published VI SVs for most of these
chemicals. Statewide health standard VI evaluations are not available for substances without
SVs. The remediator may choose to evaluate VI using the site-specific standard for these
chemicals. In addition, DEP does not consider the polycyclic aromatic hydrocarbons (PAHs) in
Table X-1 to be of VI concern because of their high boiling points, relatively low Henry’s law
constants, and very low vapor pressures.
In the case of 1,3,5-trimethylbenzene, DEP has chosen 1,2,4-trimethylbenzene as a surrogate for
inhalation toxicity. These two substances have similar chemical and toxicological
characteristics, and this selection likely results in conservative SVs.
Indoor air SVs (SV
IA
) are determined from the inhalation risk equations in U.S. EPA (2009).
This method is equivalent to that used by EPA for Regional Screening Levels and in the VISL
Calculator (U.S. EPA, 2013a, 2013b). SVs for systemic toxicants (SV
IA(nc)
) and carcinogens
(SV
IA(c)
) are calculated in units of micrograms per cubic meter (?g/m
3
).

261-0300-101 / DRAFT July 25, 2015 / Page 64
For systemic toxicants (non-carcinogens) the indoor air SV is:
For carcinogens the indoor air SV is:
For substances classified as mutagens, except for vinyl chloride and trichloroethylene, the
residential carcinogenic indoor air SV is:
For vinyl chloride the residential carcinogenic indoor air SV is:
For trichloroethylene the residential carcinogenic indoor air SV is:
As TCE has a mutagenic mode of action for the kidneys, the residential carcinogenic SV is
calculated using distinct IUR values for kidney cancer and non-Hodgkin lymphoma and liver
cancer (U.S. EPA, 2011a).
The variables and exposure factors in the above equations are defined in Table X-2. Certain
conditions are explained in Section 250.307(h).
Residential and nonresidential indoor air SVs are defined as the lower of the applicable systemic,
carcinogenic, and mutagenic values. The toxicity parameters used are from Chapter 250,
Appendix A, Table 5A (Table X-5).

261-0300-101 / DRAFT July 25, 2015 / Page 65
Table X-1. Volatile Substances Without Inhalation Toxicity Data
Regulated Substance
CAS No.
ACENAPHTHENE [PAH]
83-32-9
ACENAPHTHYLENE [PAH]
208-96-8
ACETOPHENONE
98-86-2
AMMONIUM SULFAMATE
7773-06-0
ANTHRACENE [PAH]
120-12-7
BENZOTRICHLORIDE
98-07-7
BUTYL ALCOHOL, N-
71-36-3
BUTYLATE
2008-41-5
BUTYLBENZENE, N-
104-51-8
BUTYLBENZENE, SEC-
135-98-8
BUTYLBENZENE, TERT-
98-06-6
CHLOROACETALDEHYDE
107-20-0
CHLOROBUTANE, 1-
109-69-3
CHLORONAPHTHALENE, 2-
91-58-7
CHLOROPHENOL, 2-
95-57-8
CHLOROTOLUENE, O-
95-49-8
CHLOROTOLUENE, P-
106-43-4
CRESOL, O- (METHYLPHENOL, 2-)
95-48-7
CROTONALDEHYDE
4170-30-3
CROTONALDEHYDE, TRANS-
123-73-9
DICHLOROBENZENE, 1,3-
541-73-1
DICHLOROETHYLENE, CIS-1,2-
156-59-2
DICHLOROPROPIONIC ACID, 2,2- (DALAPON)
75-99-0
DIISOPROPYL METHYLPHOSPHONATE
1445-75-6
DIMETHYL METHYLPHOSPHONATE
756-79-6
DIMETHYLANILINE, N,N-
121-69-7
DITHIANE, 1,4-
505-29-3
ETHYL DIPROPYLTHIOCARBAMATE, S- (EPTC)
759-94-4
ETHYL ETHER
60-29-7
ETHYLENE CHLORHYDRIN
107-07-3
FLUORENE [PAH]
86-73-7
FURAN
110-00-9
ISOBUTYL ALCOHOL
78-83-1
METHYL ACETATE
79-20-9
METHYLSTYRENE, ALPHA
98-83-9
METOLACHLOR
51218-45-2
MONOCHLOROACETIC ACID
79-11-8
NITROPHENOL, 2-
88-75-5
NITROPHENOL, 4-
100-02-7
PENTACHLOROETHANE
76-01-7
PHENANTHRENE [PAH]
85-01-8
PHENYL MERCAPTAN
108-98-5
PYRIDINE
110-86-1
TRICHLOROACETIC ACID
76-03-9
TRICHLOROPROPANE, 1,1,2-
598-77-6
TRIMETHYLBENZENE, 1,3,5-*
108-67-8
TRINITROGLYCEROL (NITROGLYCERIN)
55-63-0
PAH: polycyclic (or polynuclear) aromatic hydrocarbons
* The Department has determined that 1,2,4-trimethylbenzene is an appropriate surrogate for
1,3,5-trimethylbenzene, and VI screening values for 1,3,5-trimethylbenzene are based on the RfC
i
value
for 1,2,4-trimethylbenzene.

261-0300-101 / DRAFT July 25, 2015 / Page 66
Table X-2. Inhalation Risk Variables
Symbol
Term
Residential
Nonresidential
THQ
Target Hazard Quotient, systemic toxicants
1.0
1.0
RfC
i
Inhalation Reference Concentration (mg/m
3
)
Table X-5
Table X-5
AT
nc
Averaging Time for systemic toxicants (yr)
30
25
ET
Exposure Time (hr/day)
24
8
EF
Exposure Frequency (days/yr)
350
250
ED
Exposure Duration (yr)
30
25
TR
Target Risk, carcinogens
1 x 10
–5
1 x 10
–5
IUR
Inhalation Unit Risk ((?g/m
3
)
–1
)
Table X-5
Table X-5
AT
c
Averaging Time for carcinogens (yr)
70
70
AED
Combined Age-Dependent Adjustment Factor and
Exposure Duration (yr)
76
N/A
IUR
k
TCE IUR, residential, kidney cancer ((?g/m
3
)
–1
)
1.0 x 10
–6
N/A
IUR
l
TCE IUR, residential, non-Hodgkin lymphoma and
liver cancer ((?g/m
3
)
–1
)
3.0 x 10
–6
N/A
2.
Sub-Slab Soil Gas
The POA for sub-slab soil gas screening is immediately beneath the slab or basement of a
building. In some circumstances samples may be collected from behind basement walls or
below intact paved areas large enough to be representative of future inhabited buildings.
Sub-slab SVs (SV
SS
) are defined using attenuation factors from U.S. EPA (2012b). These SVs
have units of micrograms per cubic meter (?g/m
3
).
EPA derived a sub-slab attenuation factor (?
SS
) from a statistical evaluation of paired sub-slab
and indoor air sampling data at 431 residential buildings at 12 sites. The data was limited to
chlorinated VOCs. The empirical attenuation factors are defined as
?
SS
=
C
IA
/
C
SS
.
EPA’s recommended residential attenuation factor is
?
?S,R
= 0.026, the 95
th
percentile of the
screened data. DEP has adopted this attenuation factor for all chemicals, including petroleum
hydrocarbons, as a conservative approach. This residential factor also applies to nonresidential
buildings that were originally constructed for residential use (?
SS,CR
) or that have mixed
residential and commercial uses.
For nonresidential buildings that were constructed purely for nonresidential use
(e.g., commercial, industrial, and institutional buildings), DEP adjusts EPA’s attenuation factor
to account for a higher air exchange rate in such structures. The 10
th
percentile air exchange
rates for residential and commercial buildings are 0.18 and 0.60 air changes per hour,
respectively (U.S. EPA, 2011b, Ch. 19). These are conservative rates, particularly for modern
nonresidential buildings which typically have values exceeding 1 hr
–1
. The adjusted
nonresidential sub-slab attenuation factor is:

261-0300-101 / DRAFT July 25, 2015 / Page 67
Sub-slab SVs are calculated directly from the indoor air SVs using the applicable attenuation
factor:
3.
Near-Source Soil Gas
Near-source soil gas samples are collected proximal to the source to minimize the influence of
variable effects such as soil moisture, atmospheric conditions, and leakage from the surface that
can bias shallow soil gas measurements. For groundwater and SPL the POA is immediately
above the capillary zone throughout the area of the plume. For soil in the vadose zone the POA
is within or immediately above the contaminated soil. Screening may be applied when at least a
5-foot vertical section of acceptable soil or soil-like material is present between the building
foundation and the depth where the near-source soil gas sample is obtained. (If a near-source
soil gas sample is collected less than 5 feet below the foundation it may be screened using sub-
slab soil gas SVs.) Near-source soil gas SVs (SV
NS
) are defined using attenuation factors
derived from modeling as explained below. These SVs have units of micrograms per cubic
meter (?g/m
3
).
DEP estimated a near-source soil gas attenuation factor (?
NS
) by running numerous J&E model
simulations (Johnson and Ettinger, 1991; U.S. EPA, 2004). DEP utilized EPA’s advanced soil
model (version 3.1, February 2004) to determine soil gas source concentrations corresponding to
specified indoor air SVs. The simulations encompassed 12 to 16 different chemicals, the full
suite of soil types, and water-filled porosities ranging from residual saturation to the EPA default
values in the J&E manual. DEP made conservative assumptions of a shallow source (5 ft.) and a
high vapor flow rate (
Q
soil
= 5 L/min). EPA’s default building characteristics for a small, slab-
on-grade building were retained. The models had low, 10
th
percentile values for the air exchange
rate (0.18 hr
–1
residential, 0.60 hr
–1
nonresidential; U.S. EPA, 2011b, Ch. 19).
The results of this modeling indicated that there is relatively little variability in the soil gas
attenuation factor for different conditions. The silt soil type has the highest attenuation factor
because of its low residual water content and relatively high air-filled porosity. Representative
factors are
?
NS,R
= 0.005 and
?
NS,NR
= 0.001 for residential and nonresidential scenarios. To
further assess these values DEP examined the soil gas data in EPA’s VI database (U.S. EPA,
2012b). Of 46 buildings at four sites with paired deep soil gas (>10 ft.) and indoor air
measurements, only one exceeded the modeled attenuation factor of 0.005. (This exception had
a calculated attenuation factor of 0.0075.)
Near-source SVs are calculated directly from the indoor air values using the applicable
attenuation factor:
4.
Soil
Soil samples may be collected in the unsaturated zone as part of the site characterization or a
demonstration of attainment following remediation. The POA is throughout the area of

261-0300-101 / DRAFT July 25, 2015 / Page 68
contamination. Screening may be applied to samples collected at any depth below the building
foundation and above the water table. SPL should not be present. Soil SVs (SV
SOIL
) are defined
as the higher of a calculated SV and the generic soil-to-groundwater pathway numeric value for a
used aquifer in Chapter 250. Soil SVs have units of milligrams per kilogram, dry basis (mg/kg).
The calculated SV is based on equilibrium partitioning of the contaminant between the sorbed
phase on soil, the dissolved phase in pore water, and the vapor phase in the pore space. This
relationship is given in Section 250.308(a)(3), with the dilution factor set to 1:
(
)
w e e V′
SOIL
is the calculated SV for soil (mg/kg) and
C
pw
is the concentration in pore water
(?g/L). The other parameters are defined in Table X-3. The value of
f
oc
is from
Section 250.308(a)(3). The dry bulk density used is representative of typical soil types
(U.S. EPA, 2004). DEP defines
?
w
equal to 0.1 to represent relatively dry conditions, close to
residual saturation, beneath a building.
The pore water concentration is related to the pore vapor concentration (
C
pv
) by Henry’s law:
where
C
pv
has units of micrograms per cubic meter (?g/m
3
).
H
′ is calculated at a soil
temperature of 11°C (52°F).
The allowable pore vapor concentration is determined from the SV
IA
by means of soil
attenuation factors:
The soil attenuation factors were determined through testing with the J&E model as described in
Section X.3, but with a source depth of 0.5 feet, directly below the slab. The corresponding
factors are
?
SOIL,R
= 0.01 and
?
SOIL,NR
= 0.002.
The soil SVs are limited by the residual saturation value of 10,000 mg/kg as defined in
Section 250.305(b).
Each calculated SV is compared to the generic soil-to-groundwater pathway numeric value for a
used aquifer with total dissolved solids less than or equal to 2,500 mg/L (Chapter 250,
Appendix A, Table 3B), and DEP defines the higher of the two values as the soil SV for VI
(SV
SOIL
). The generic soil-to-groundwater numeric values are considered appropriate for VI
screening because soil contamination that is unable to impact aquifers in excess of groundwater
MSCs is also unlikely to pose an excess inhalation risk. DEP also recognizes that the infinite
source assumption used to calculate SVs is very conservative, that soil contamination commonly
occurs outside the footprint of potentially impacted buildings, and that these SVs do not account
for the natural biological degradation of petroleum hydrocarbons in soil vapor.

261-0300-101 / DRAFT July 25, 2015 / Page 69
Table X-3. Soil Partitioning Parameters
Symbol
Description
Value
f
oc
fraction organic carbon in soil
0.0025
K
oc
organic carbon partitioning coefficient (L/kg)
Table X-5
?
w
water-filled porosity of soil
0.1
b
dry bulk density of soil (kg/L)
1.5
H
Henry’s law constant at soil temperature
Table X-5
5.
Groundwater
Groundwater data that have been collected as part of the site characterization or a demonstration
of attainment may be used for VI screening. The POA is throughout the area of the groundwater
plume. Certain conditions apply to groundwater screening: groundwater is not in contact with
the building foundation and acceptable soil or soil-like material is present between the
groundwater and the foundation. Groundwater samples are collected from properly constructed
monitoring wells screened across the water table, and the wetted length of the well screen should
be no more than 10 feet. SPL contaminants are not present.
Groundwater SVs (SV
GW
) for depths less than 5 feet are defined by the groundwater MSCs for a
used aquifer. Groundwater SVs for depths of 5 feet and greater are defined as the higher of a
calculated SV based on EPA attenuation factors and the groundwater MSCs for a used aquifer.
SVs have units of micrograms per liter (?g/L).
EPA derived a groundwater attenuation factor (?
GW
) from a statistical evaluation of paired
groundwater and indoor air sampling data at 774 residential buildings at 24 sites (U.S. EPA,
2012b). The data was limited to chlorinated VOCs. The empirical attenuation factors are
defined as
?
GW
=
C
IA
/
C
GW
.
EPA’s recommended residential attenuation factor for groundwater at least 5 feet deep is 0.0012,
the 95
th
percentile of the screened data. DEP has adopted this attenuation factor for all
chemicals, including petroleum hydrocarbons, as a conservative approach. This residential
factor (?
GW,R
) also applies to nonresidential buildings that were originally constructed for
residential use (?
GW,CR
) or that have mixed residential and commercial use.
For nonresidential buildings that were constructed purely for nonresidential use
(e.g., commercial, industrial, and institutional buildings), DEP adjusts EPA’s attenuation factor
to account for a higher air exchange rate in such structures. The 10
th
percentile air exchange
rates for residential and commercial buildings are 0.18 and 0.60 air changes per hour,
respectively (U.S. EPA, 2011b, Ch. 19). The adjusted nonresidential groundwater attenuation
factor is:

261-0300-101 / DRAFT July 25, 2015 / Page 70
Calculated groundwater SVs (SV
GW
) are determined from the indoor air SVs using the
applicable attenuation factor and a conversion from soil gas to a dissolved concentration via
Henry’s law:
where
H′
is the nondimensional Henry’s law constant at the groundwater temperature
(Table X-5). DEP calculates the Henry’s law constant at a groundwater temperature of
11°C (52°F).
DEP compares each calculated SV to the groundwater MSC for a used aquifer with total
dissolved solids less than or equal to 2,500 mg/L (Chapter 250, Appendix A, Table 1). DEP
defines the groundwater SV for VI (SV
GW
) for depths of 5 feet and greater as the maximum of
the calculated SV (SV
GW
) and the MSC, limited by the aqueous solubility (
S
). DEP regards the
groundwater MSCs as suitable for VI screening at any depth because they are acceptable for
water used inside homes, including inhalation exposures.
6.
Attenuation Factor Summary
The attenuation factors used to calculate the VI SVs are listed in Table X-4. The sub-slab and
groundwater attenuation factors are based on EPA’s empirical database (U.S. EPA, 2012b). The
near source soil gas and soil attenuation factors are defined from DEP’s modeling studies.
Table X-4. Attenuation Factors
Environmental
Medium
?
R
?
NR
?
CR
Sub-slab soil gas
0.026
0.0078
0.026
Near-source soil gas
0.005
0.001
0.005
Soil
0.01
0.002
0.01
Groundwater
0.0012
0.00036
0.0012
R: residential buildings
NR: nonresidential buildings
CR: residential building converted to nonresidential use
The near-source and sub-slab soil gas attenuation factors may also be used within a site-specific
standard risk assessment for estimating indoor air concentrations or for calculating SVs from
EPA’s regional screening levels (RSLs).

261-0300-101 / DRAFT July 25, 2015 / Page 71
Table X-5. Vapor Intrusion Screening Value Calculation Parameters
Regulated Substance
CAS No.
MW
K
oc
S
T
B
T
C
?
H
v,b
H
H
RfC
i
IUR
(g/mol)
(L/kg)
(mg/L)
(°C)
(K)
(cal/mol)
(atm-m
3
/mol)
(@
T
gw
)
(mg/m
3
)
(
?
g/m
3
)
–1
ACETALDEHYDE
75-07-0
44
4.1
1,000,000
20
466
6,157
6.7 x 10
–5
1.6 x 10