1. TABLE OF CONTENTS
      2. SECTION IV: VAPOR INTRUSION
      3. A. Introduction
      4. B. Definition and Use of Important Terms
      5. C. Overview of the VI Evaluation Process
      6. 1. VI Conceptual Site Model
      7. Figure IV-1: VI Screening Value POAs and Vertical Petroleum Proximity Distances
      8. 2. Screening Values and Points of Application (POA)
      9. 3. Guidelines for Evaluating VI Using a Combination of Standards
      10. VI Assessment Needs When Using a Combination of Standards
      11. Act 2 Standard
      12. Used to Address
      13. Soil and
      14. Groundwater
      15. VI Evaluation Tools
      16. ScreeningValues inTables IV-
      17. Use 1/10ScreeningValues inTables IV-
      18. Modeling
      19. Assessment
      20. Mitigationwith EC
      21. (i.e.,
      22. pathwayelimination)
      23. Remediation
      24. D. Preferential Pathway Evaluation
      25. 1. External Preferential Pathways
      26. Figure IV-3: The Role of an External Preferential Pathway in the VI Evaluation
      27. 2. Significant Foundation Openings
      28. E. Use of Proximity Distances
      29. Figure IV-4: Use of Proximity Distances to Evaluate Potential VI Sources
      30. F. Soil and Groundwater VI Screening
      31. Soil or Groundwater Screening Additional Considerations
      32. Soil concentrations < SVSOIL
      33. Soil concentrations < generic soil-to-groundwater numeric value
      34. Groundwater concentrations< SVGW
      35. Groundwater concentrations <
      36. used aquifer groundwater MSC
      37. 1. Soil and Groundwater Screening Values
      38. 2. Soil and Groundwater Screening Methods
      39. G. Alternative VI Assessment Options
      40. Alternative Assessment Option Additional Considerations
      41. Near-source soil gas
      42. concentrations < SVNS
      43. Near-source soil gas
      44. concentrations < SVSS
      45. Sub-slab soil gas concentrations
      46. < SVSS for existing buildings
      47. Sub-slab soil gas concentrations< SVIA for existing buildings
      48. Indoor air concentrations< SVIA at existing buildings
      49. Vapor intrusion modeling usingacceptable input parameters
      50. 1. Soil Gas and Indoor Air Screening Values
      51. 2. Soil Gas and Indoor Air Screening Methods
      52. 3. Vapor Intrusion Modeling
      53. H. Mitigation and Activity and Use Limitations
      54. I. Remediating and Reassessing the VI Pathway
      55. J. Addressing 25 Pa. Code Chapter 250 Requirements
      56. K. Evaluating the VI Pathway Under the Site-Specific Standard
      57. 1. Overview
      58. 2. Preferential Pathway Evaluation
      59. 3. Use of Proximity Distances
      60. 4. Site-Specific Standard VI Screening
      61. Sample Type
      62. Attenuation Factor
      63. Residential
      64. Residential
      65. ConvertedResidential
      66. 5. Performing a VI Risk Assessment and Modeling
      67. 6. Mitigation and Remediation
      68. 7. Using an OSHA Program to Address VI
      69. 8. Addressing Chapter 250 Requirements
      70. Figure IV-9: Screening Value Use Restrictions
      71. L. References
      72. M. Tables
      73. Table IV-1: Groundwater SHS Vapor Intrusion Screening Values (SVGW)
      74. Regulated Substance CAS No.
      75. Residential
      76. (μg/L)
      77. Nonresidential
      78. (μg/L)
      79. ConvertedResidential
      80. (μg/L)
      81. Regulated Substance CAS No.
      82. Residential
      83. (μg/L)
      84. Nonresidential
      85. (μg/L)
      86. ConvertedResidential
      87. (μg/L)
      88. Regulated Substance CAS No.
      89. Residential
      90. (μg/L)
      91. Nonresidential
      92. (μg/L)
      93. ConvertedResidential
      94. (μg/L)
      95. Regulated Substance CAS No.
      96. Residential
      97. (μg/L)
      98. Nonresidential
      99. (μg/L)
      100. ConvertedResidential
      101. (μg/L)
      102. Regulated Substance CAS No.
      103. Residential
      104. (μg/L)
      105. Nonresidential
      106. (μg/L)
      107. ConvertedResidential
      108. (μg/L)
      109. Table IV-2: Soil SHS Vapor Intrusion Screening Values (SVSOIL)
      110. Regulated Substance CAS No.
      111. Residential
      112. (mg/kg)
      113. Nonresidential
      114. (mg/kg)
      115. ConvertedResidential(mg/kg)
      116. Regulated Substance CAS No.
      117. Residential
      118. (mg/kg)
      119. Nonresidential
      120. (mg/kg)
      121. ConvertedResidential(mg/kg)
      122. Regulated Substance CAS No.
      123. Residential
      124. (mg/kg)
      125. Nonresidential
      126. (mg/kg)
      127. ConvertedResidential(mg/kg)
      128. Regulated Substance CAS No.
      129. Residential
      130. (mg/kg)
      131. Nonresidential
      132. (mg/kg)
      133. ConvertedResidential(mg/kg)
      134. Regulated Substance CAS No.
      135. Residential
      136. (mg/kg)
      137. Nonresidential
      138. (mg/kg)
      139. ConvertedResidential(mg/kg)
      140. Table IV-3: Near-Source Soil Gas SHS Vapor Intrusion Screening Values (SVNS)
      141. Regulated Substance CAS No.
      142. Residential
      143. (μg/m
      144. Nonresidential
      145. (μg/m
      146. ConvertedResidential(μg/m
      147. Regulated Substance CAS No.
      148. Residential
      149. (μg/m
      150. Nonresidential
      151. (μg/m
      152. ConvertedResidential(μg/m
      153. Regulated Substance CAS No.
      154. Residential
      155. (μg/m
      156. Nonresidential
      157. (μg/m
      158. ConvertedResidential(μg/m
      159. Regulated Substance CAS No.
      160. Residential
      161. (μg/m
      162. Nonresidential
      163. (μg/m
      164. ConvertedResidential(μg/m
      165. Table IV-4: Sub-Slab Soil Gas SHS Vapor Intrusion Screening Values (SVSS)
      166. Regulated Substance CAS No.
      167. Residential
      168. (μg/m
      169. Nonresidential
      170. (μg/m
      171. ConvertedResidential(μg/m
      172. Regulated Substance CAS No.
      173. Residential
      174. (μg/m
      175. Nonresidential
      176. (μg/m
      177. ConvertedResidential(μg/m
      178. Regulated Substance CAS No.
      179. Residential
      180. (μg/m
      181. Nonresidential
      182. (μg/m
      183. ConvertedResidential(μg/m
      184. Regulated Substance CAS No.
      185. Residential
      186. (μg/m
      187. Nonresidential
      188. (μg/m
      189. ConvertedResidential(μg/m
      190. Table IV-5: Indoor Air SHS Vapor Intrusion Screening Values (SVIA)
      191. Regulated Substance CAS No.
      192. Residential
      193. (μg/m
      194. Nonresidential
      195. (μg/m
      196. Regulated Substance CAS No.
      197. Residential
      198. (μg/m
      199. Nonresidential
      200. (μg/m
      201. Regulated Substance CAS No.
      202. Residential
      203. (μg/m
      204. Nonresidential
      205. (μg/m
      206. Regulated Substance CAS No.
      207. Residential
      208. (μg/m
      209. Nonresidential
      210. (μg/m
      211. Table IV-6: Collection of Data for Vapor Intrusion Screening
      212. Sample Conditions for VI Data Collection
      213. Sample Conditions for VI Data Collection
      214. Characterization Data Vapor Intrusion Screening Conditions
      215. Attainment Data Vapor Intrusion Screening Conditions
      216. Characterization Data Vapor Intrusion Screening Conditions
      217. Vapor Intrusion Screening Conditions
      218. APPENDICES
      219. Appendix IV-A: Methodology for Developing SHS Vapor Intrusion Screening Values
      220. 1. Indoor Air
      221. Table IV-A-1: Volatile Substances Without Inhalation Toxicity Data
      222. Regulated Substance CAS No.
      223. Regulated Substance CAS No.
      224. Table IV-A-2: Inhalation Risk Variables
      225. 2. Sub-Slab Soil Gas
      226. 3. Near-Source Soil Gas
      227. 4. Soil
      228. Table IV-A-3: Soil Partitioning Parameters
      229. 5. Groundwater
      230. 6. Building Foundation Openings
      231. 7. Attenuation Factor Summary
      232. Table IV-A-4: Attenuation Factors
      233. Table IV-A-5: Vapor Intrusion Screening Value Calculation Parameters
      234. Regulated Substance CAS No.
      235. MW Koc S TB TC ΔHv,b H H′ RfCi IUR
      236. (g/mol) (L/kg) (mg/L) (°C) (K) (cal/mol) (atm-m
      237. 3/mol) (@ Tgw) (mg/m
      238. 3) (μg/m
      239. Regulated Substance CAS No.
      240. MW Koc S TB TC ΔHv,b H H′ RfCi IUR
      241. (g/mol) (L/kg) (mg/L) (°C) (K) (cal/mol) (atm-m
      242. 3/mol) (@ Tgw) (mg/m
      243. 3) (μg/m
      244. Regulated Substance CAS No.
      245. MW Koc S TB TC ΔHv,b H H′ RfCi IUR
      246. (g/mol) (L/kg) (mg/L) (°C) (K) (cal/mol) (atm-m
      247. 3/mol) (@ Tgw) (mg/m
      248. 3) (μg/m
      249. Regulated Substance CAS No.
      250. MW Koc S TB TC ΔHv,b H H′ RfCi IUR
      251. (g/mol) (L/kg) (mg/L) (°C) (K) (cal/mol) (atm-m
      252. 3/mol) (@ Tgw) (mg/m
      253. 3) (μg/m
      254. Regulated Substance CAS No.
      255. MW Koc S TB TC ΔHv,b H H′ RfCi IUR
      256. (g/mol) (L/kg) (mg/L) (°C) (K) (cal/mol) (atm-m
      257. 3/mol) (@ Tgw) (mg/m
      258. 3) (μg/m
      259. Appendix IV-B: Vapor Intrusion Modeling Guidance
      260. 1. Background
      261. 2. Assumptions
      262. 3. J&E Model Parameter Adjustments
      263. Table IV-B-1: Adjustable J&E Model Input Parameters and Default Values
      264. Parameter Symbol Residential Nonresidential
      265. Table IV-B-2: Pennsylvania Shallow Soil and Groundwater Temperatures
      266. Northwest Region Northcentral Region Northeast Region
      267. Table IV-B-3: Guidance for the Selection of the J&E Model Soil Type
      268. Predominant Soil Types in Boring Logs
      269. Recommended
      270. Soil Classification
      271. Figure IV-B-1: USDA SCS Soil Classification Chart
      272. 4. Site-Specific Standard Parameter Adjustments
      273. Table IV-B-4: J&E Model Default Exposure Factors
      274. 5. Petroleum Hydrocarbons
      275. 6. Attenuation Factor Risk Calculations
      276. 7. Report Contents
      277. Appendix IV-C: Vapor Intrusion Sampling Methods
      278. 1. Introduction
      279. a) Applicability
      280. b) Conceptual Site Model Development
      281. Spatial and Temporal Variability Considerations
      282. 2. Sampling Locations
      283. Figure IV-C-1: Sampling Location Options: Soil and Groundwater Sources
      284. Sample Description Screen
      285. Figure IV-C-2: Sampling Location Options: External Preferential Pathway
      286. Figure IV-C-3: Sampling Location Options: Significant Foundation Opening
      287. 3. Near-Source Soil Gas Sampling
      288. a) Description
      289. Table IV-C-1: Capillary Fringe Height Estimates
      290. Soil Type Lcz (cm) Lcz (ft)
      291. b) Sample Point Installation
      292. i) Installation of Temporary Points
      293. ii) Installation and Construction of Semi-Permanent Points
      294. 4. Sub-Slab Soil Gas Sampling
      295. a) Description
      296. b) Location
      297. c) Sample Point Installation
      298. 5. Indoor Air Sampling
      299. a) Sampling Indoor Air
      300. b) Outdoor Ambient Air Sampling
      301. 6. Sampling Soil Gas for Oxygen Content
      302. 7. Sampling Separate Phase Liquids
      303. Table IV-C-2: SPL Vapor Phase Parameters
      304. 8. Quality Assurance and Quality Control Procedures and Methods
      305. a) Sampling Procedures and Methods
      306. i) Pre-Sampling Survey
      307. ii) Sampling Equipment
      308. iii) Sampling Point Construction
      309. iv) Equilibration
      310. v) Leak Testing/Detection for Subsurface Sample Collection
      311. vi) Purging
      312. vii) Sampling Rates
      313. viii) Sample Recordation
      314. b) Data Quality Objective (DQO) Process, Sampling and Data Quality Assessment
      315. Process
      316. c) QA/QC Samples
      317. d) Analytical Methods
      318. Parameter Method
      319. Sample
      320. Media/Storage
      321. Description
      322. Method Holding
      323. e) Data Evaluation
      324. 9. Active Sub-Slab Depressurization System Testing
      325. a) Description
      326. b) Performance Testing Methods
      327. Appendix IV-D: OSHA Program Vapor Intrusion Checklist

261-0300-101 / DRAFT December 16, 2017 / Page IV-i
TABLE OF CONTENTS
SECTION IV: VAPOR INTRUSION...............................................................................................IV-1
A.
Introduction................................................................................................................................ IV-1
B.
Definition and Use of Important Terms..................................................................................... IV-3
C.
Overview of the VI Evaluation Process..................................................................................... IV-7
1.
VI Conceptual Site Model ............................................................................................. IV-7
2.
Screening Values and Points of Application (POA).................................................... IV-10
3.
Guidelines for Evaluating VI Using a Combination of Standards............................... IV-11
D.
Preferential Pathway Evaluation.............................................................................................. IV-14
1.
External Preferential Pathways .................................................................................... IV-15
2.
Significant Foundation Openings ................................................................................ IV-18
E.
Use of Proximity Distances ..................................................................................................... IV-21
F.
Soil and Groundwater VI Screening ........................................................................................ IV-24
1.
Soil and Groundwater Screening Values ..................................................................... IV-24
2.
Soil and Groundwater Screening Methods .................................................................. IV-25
G.
Alternative VI Assessment Options......................................................................................... IV-28
1.
Soil Gas and Indoor Air Screening Values .................................................................. IV-28
2.
Soil Gas and Indoor Air Screening Methods ............................................................... IV-29
3.
Vapor Intrusion Modeling............................................................................................ IV-32
H.
Mitigation and Activity and Use Limitations .......................................................................... IV-33
I.
Remediating and Reassessing the VI Pathway ........................................................................ IV-35
J.
Addressing Chapter 250 Requirements ................................................................................... IV-36
K.
Evaluating the VI Pathway Under the Site-Specific Standard................................................. IV-37
1.
Overview...................................................................................................................... IV-37
2.
Preferential Pathway Evaluation.................................................................................. IV-38
3.
Use of Proximity Distances ......................................................................................... IV-38
4.
Site-Specific Standard VI Screening ........................................................................... IV-38
5.
Performing a VI Risk Assessment and Modeling........................................................ IV-40
6.
Mitigation and Remediation ........................................................................................ IV-41
7.
Using an OSHA Program to Address VI ..................................................................... IV-41
8.
Addressing Chapter 250 Requirements ....................................................................... IV-42
L.
References................................................................................................................................ IV-48
M.
Tables....................................................................................................................................... IV-54
Table IV-1: Groundwater SHS Vapor Intrusion Screening Values (SV
GW
)........................... IV-54
Table IV-2: Soil SHS Vapor Intrusion Screening Values (SV
SOIL
)........................................ IV-59
Table IV-3: Near-Source Soil Gas SHS Vapor Intrusion Screening Values (SV
NS
).............. IV-64
Table IV-4: Sub-Slab Soil Gas SHS Vapor Intrusion Screening Values (SV
SS
).................... IV-68
Table IV-5: Indoor Air SHS Vapor Intrusion Screening Values (SV
IA
) ................................ IV-72
Table IV-6: Collection of Data for Vapor Intrusion Screening .............................................. IV-76
Table IV-7: Application of Statewide Health Standard Vapor Intrusion Screening
Criteria ......................................................................................................................... IV-78
APPENDIX IV-A: METHODOLOGY FOR DEVELOPING SHS VAPOR
INTRUSION SCREENING VALUES.............................................................................................IV-82
1.
Indoor Air..................................................................................................................... IV-82
2.
Sub-Slab Soil Gas ........................................................................................................ IV-85
3.
Near-Source Soil Gas................................................................................................... IV-86

261-0300-101 / DRAFT December 16, 2017 / Page IV-ii
4.
Soil ............................................................................................................................... IV-87
5.
Groundwater ................................................................................................................ IV-88
6.
Building Foundation Openings .................................................................................... IV-89
7.
Attenuation Factor Summary....................................................................................... IV-90
APPENDIX IV-B: VAPOR INTRUSION MODELING GUIDANCE........................................IV-96
1.
Background .................................................................................................................. IV-96
2.
Assumptions................................................................................................................. IV-97
3.
J&E Model Parameter Adjustments............................................................................. IV-97
4.
Site-Specific Standard Parameter Adjustments ......................................................... IV-103
5.
Petroleum Hydrocarbons ........................................................................................... IV-104
6.
Attenuation Factor Risk Calculations ........................................................................ IV-105
7.
Report Contents ......................................................................................................... IV-105
APPENDIX IV-C: VAPOR INTRUSION SAMPLING METHODS........................................IV-107
1.
Introduction................................................................................................................ IV-107
a)
Applicability .................................................................................................. IV-107
b)
Conceptual Site Model Development ............................................................ IV-107
c)
Spatial and Temporal Variability Considerations.......................................... IV-107
2.
Sampling Locations ................................................................................................... IV-109
3.
Near-Source Soil Gas Sampling ................................................................................ IV-113
a)
Description..................................................................................................... IV-113
b)
Sample Point Installation ............................................................................... IV-113
i)
Installation of Temporary Points ....................................................... IV-113
ii)
Installation and Construction of Semi-Permanent Points .................. IV-114
4.
Sub-Slab Soil Gas Sampling...................................................................................... IV-114
a)
Description..................................................................................................... IV-114
b)
Location ......................................................................................................... IV-114
c)
Sample Point Installation ............................................................................... IV-114
5.
Indoor Air Sampling .................................................................................................. IV-115
a)
Sampling Indoor Air ...................................................................................... IV-115
b)
Outdoor Ambient Air Sampling..................................................................... IV-116
6.
Sampling Soil Gas for Oxygen Content..................................................................... IV-117
7.
Sampling Separate Phase Liquids.............................................................................. IV-117
8.
Quality Assurance and Quality Control Procedures and Methods ............................ IV-119
a)
Sampling Procedures and Methods................................................................ IV-119
i)
Pre-Sampling Survey ......................................................................... IV-119
ii)
Sampling Equipment.......................................................................... IV-119
iii)
Sampling Point Construction ............................................................. IV-120
iv)
Equilibration ...................................................................................... IV-121
v)
Leak Testing/Detection for Subsurface Sample Collection............... IV-121
vi)
Purging............................................................................................... IV-122
vii)
Sampling Rates .................................................................................. IV-122
viii)
Sample Recordation ........................................................................... IV-123
b)
Data Quality Objective (DQO) Process, Sampling and Data
Quality Assessment Process .......................................................................... IV-123
c)
QA/QC Samples............................................................................................. IV-123
d)
Analytical Methods........................................................................................ IV-124
e)
Data Evaluation.............................................................................................. IV-126

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9.
Active Sub-Slab Depressurization System Testing ................................................... IV-126
a)
Description..................................................................................................... IV-126
b)
Performance Testing Methods ....................................................................... IV-127
APPENDIX IV-D: OSHA PROGRAM VAPOR INTRUSION CHECKLIST.........................IV-128

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SECTION IV: VAPOR INTRUSION
A.
Introduction
Releases of volatile and some semi-volatile regulated substances to soil or groundwater can
result in vapor-phase intrusion of these regulated substances into indoor air. The resulting
impacts to indoor air may pose a threat to human health in 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, current or future 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 used or planned to be used 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, mitigation or remediation.
This section 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 (SHS) and the site-specific standard (SSS).
As such, this guidance establishes screening values and assessment options that can be used
under the SHS 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 SSS or mitigation.
The VI screening value tables in this guidance are not meant to
evaluate VI under the SSS except under certain circumstances.
Guidance on VI evaluations
under the SSS, including the use of a human health inhalation risk assessment, is provided in
Section IV.K.
25 Pa. Code § 250.312 requires an assessment of the VI exposure pathway in an SHS final report
(FR). An exposure pathway assessment that includes VI is required by 25 Pa. Code § 250.404,
and a risk assessment is required by 25 Pa. Code § 250.405 under the SSS. VI must be addressed
for existing inhabited buildings and undeveloped areas of the property where inhabited buildings
are planned to be constructed in the future. The VI pathway must be addressed for Special
Industrial Area (SIA) sites and for storage tank corrective action sites because cleanups at these
sites ultimately achieve either the SHS or the SSS. A VI evaluation is generally 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 SHS and SSS at any
time in the evaluation process. Mitigation can be used in lieu of a complete evaluation of
the VI pathway. When choosing preemptive mitigation, the remediator needs to implement
postremediation care to ensure: (1) that potential risks associated with VI will be evaluated
and addressed when an inhabited building is constructed in the future or (2) that
appropriate mitigation measures will be taken in lieu of a complete evaluation in buildings
that exist or are constructed on the property. Mitigation, even if preemptive, requires a
cleanup plan or remedial action plan (RAP). It is also important to note that any
unplanned change to a property’s use that results in a change in the VI exposure pathway
will require additional VI evaluation to account for that change in exposure. In order to
demonstrate attainment of an Act 2 standard for soil and/or groundwater, current or
future planned inhabited buildings need to be evaluated for VI in the FR. If there are no

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plans for future construction of inhabited buildings at the site, the remediator may choose,
but is not required, to use an activity and use limitation (AUL) to address possible future
VI issues.
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 SHS by following the requirements in 25 Pa. Code
§ 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 25 Pa. Code § 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 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.
The Department will not require remediators to amend or resubmit reports that have been
approved under previous versions of this guidance.
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.

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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 in Figure IV-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 in Figure IV-1 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.
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 VI.
o
Use
- POAs guide the selection of indoor air, sub-slab soil gas, near-source soil
gas, soil, and groundwater sampling locations. See Section IV.C.2. The
relationship of the POAs to the building, the hydrogeologic zones, and the
contamination are displayed in Figure IV-1. Sampling guidance for each POA is
provided in Table IV-6 and Appendix IV-C.
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 VI 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 and fill (including gravel)
coarser than sand or with air-filled porosity greater than silt may not constitute
acceptable soil. Conversely, fill material that is otherwise soil-like and does not

261-0300-101 / DRAFT December 16, 2017 / Page IV-4
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
the calculated groundwater screening values. The presence of acceptable soil or
soil-like material is also a condition for using vertical proximity distances and
applying separation distances for preferential pathways. Acceptable soil or soil-
like material should NOT exhibit any of the following characteristics:
obvious contamination by a regulated substance of VI concern
(e.g., staining or odors);
readings from an appropriate field screening instrument in the headspace
above soil samples that are greater than 100 ppmv;
evidence of SPL; and
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. 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
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 enhances vapor migration
from a potential VI source to or into an inhabited building. An
external
preferential pathway
is a channel or conduit that allows for a greater vapor
flux than ordinary diffusion through vadose zone soil. A
significant
foundation opening
is a breach in a building foundation or basement wall
that may amplify the entry of subsurface vapors.
o
Use
- A feature must be proximal to both the contamination and a building
and have sufficient volume to be a preferential pathway. A significant
opening in a building foundation, such as a dirt basement floor, can also
act as 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
certain screening values. Significant foundation openings may be sealed
to inhibit vapor entry. Additional information regarding how to identify

261-0300-101 / DRAFT December 16, 2017 / Page IV-5
and evaluate preferential pathways is provided in Section IV.D and an
example is shown in Figure IV-3.
Proximity Distance:
o
Definition
- The minimum distance, in the absence of a preferential
pathway, which a potential VI source (see definition below) must be from
a building or where a future inhabited building is planned to be
constructed, to not pose a potential unacceptable VI risk.
o
Use
- The presence of SPL 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
five 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 IV.E for
further guidance on proximity distances, and see Figure IV-4 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 may be a potential VI source if it contains substances of
VI concern. SPL may be analyzed to make this determination
(Appendix IV-C, Section IV-C.7). The presence of SPL containing
substances of VI concern provides one basis for limiting the applicability
of screening values and the modeling assessment option. As shown in
Figure IV-5, the presence of an 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 numeric values since they also

261-0300-101 / DRAFT December 16, 2017 / Page IV-6
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 IV-5). 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 by a regulated substance of VI concern under
any one of the following conditions constitutes a potential VI source:
in the unsaturated zone, soil exceeding SHS screening values
within proximity distances;
in the saturated zone, groundwater exceeding SHS screening
values within proximity distances;
as SPL within proximity distances; and
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 Section IV.D and
Figure IV-3 for preferential pathways and Section IV.E and Figure IV-4
for proximity distances. When utilizing the SSS VI evaluation process, a
potential VI source is determined by exceedances of SHS soil and
groundwater screening values (Section IV.K.4.).

261-0300-101 / DRAFT December 16, 2017 / Page IV-7
C.
Overview of the VI Evaluation Process
This guidance offers a flexible VI evaluation process for the SHS and SSS that provides multiple
alternatives to the remediator. Figures IV-6 and IV-7 present flowcharts outlining the process
for each standard, which is described in detail in the following sections. It is important to note
that the purpose of Figures IV-6 and IV-7 is to illustrate how all of the steps in the VI evaluation
process fit together. Figures IV-6 and IV-7 should not be used as your sole guide for performing
a VI evaluation; rather, they should be used in conjunction with the text of this guidance.
The principal steps of a VI evaluation under the SHS (Figure IV-6) are:
Develop the CSM and assess the presence of preferential pathways;
Identify potential VI sources from exceedances of soil and groundwater screening values
within proximity distances and/or the occurrence of SPL;
Utilize alternative assessment options including screening near-source soil gas, sub-slab
soil gas, or indoor air data, or conducting VI modeling;
Mitigate buildings using activity and use limitations;
Remediate the soil and/or groundwater contamination and reassess the pathway;
Address the 25 Pa. Code Chapter 250 SHS 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. (See Section IV.K.1. for
an overview of the SSS process.)
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. Such conditions include, but are not limited to, those that may result in
injury or death resulting from inaction, such as acute toxicity to sensitive receptors (e.g.,
fetal cardiac malformations from TCE exposure (U.S. EPA, 2011a)), a fire or explosion
hazard, or atmospheres that cause marked discomfort or sickness.
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
drives the design of a sampling plan (Appendix IV-C), 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 IV-B). 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).

261-0300-101 / DRAFT December 16, 2017 / Page IV-8
Figure IV-1: VI Screening Value POAs and Vertical Petroleum Proximity Distances

261-0300-101 / DRAFT December 16, 2017 / Page IV-9
The goal of the VI CSM is to describe how site characteristics, such as subsurface and
building conditions, might influence both the distribution of substances of VI concern in
soil gas and the potential indoor air quality of structures in the vicinity of a soil or
groundwater source of substances of VI concern. Concentrations of substances of
VI concern in soil gas attenuate, or decrease, as the substances of VI concern move away
from the source, through the soil, through the foundation, and into indoor air. The extent
of attenuation is related to site conditions, building characteristics, 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 IV-A).
The level of 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 VI. 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.
Some important elements of the VI CSM are included in the list below (California EPA,
2011a; Massachusetts DEP, 2011; U.S. EPA, 2012a, 2015a; Hawaii DoH, 2014). Some
elements may not be known or pertinent to the case, and this does not imply a deficient
CSM.
Sources of contamination—origins, locations, substances, and concentrations;
presence of SPL
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, perennial clean water lens
Fate and transport—biodegradation of petroleum hydrocarbons, transformation of
substances into regulated daughter products
Weather—precipitation, barometric pressure changes, wind, frozen ground
Building construction—basement, slab on grade, or crawl space; a garage that is
open to the atmosphere in between the ground surface and the occupied areas
Foundation openings—cracks, gaps, sumps, French drains, floor drains
Building heating and ventilation
Background sources—indoor air contaminants, ambient air pollution

261-0300-101 / DRAFT December 16, 2017 / Page IV-10
Receptor types—residential, nonresidential, sensitive receptors; potential future
development
2.
Screening Values and Points of Application (POA)
SHS screening values for regulated substances of VI concern are published in
Tables IV-1 through IV-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
attenuation factors representative of residential structures but exposure factors for
nonresidential settings. When a building has both residential and nonresidential uses
(e.g., apartments over a retail store), the remediator may need to evaluate VI with both
residential and nonresidential screening values.
The remediator should determine which structures at a site are inhabited and intended for
human occupancy. Structures that are not routinely occupied, such as storage sheds or
confined spaces, are not considered inhabited buildings. Structures that are not fully
enclosed (e.g., carports, shelters) are also not inhabited buildings. Basements are
generally regarded as an occupied space in a building; crawl spaces are not regarded as
occupied space.
The POA for each of the screening values is shown on Figure IV-1. Groundwater
screening values (SVGW) 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 ten feet or less of the water table. Soil screening
values (SVSOIL) apply throughout the volume of contaminated soil in the unsaturated
zone. Near-source soil gas screening values (SVNS) 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, except in
some cases if it penetrates the building foundation (Section IV.D). Sub-slab soil gas
screening values (SVSS) 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 (SVIA) 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 A). Therefore, SHS and SSS VI evaluations are not required for substances
without screening values. However, the remediator could choose to address the
VI pathway by demonstrating that the concentrations for such substances are below
practical quantitation limits (PQLs) or by installing a mitigation system. If soil
concentrations are less than generic soil-to-groundwater numeric values and groundwater
concentrations are less than used aquifer medium-specific concentrations (MSCs), then
there is no potential VI source. In addition, proximity distances are applicable to

261-0300-101 / DRAFT December 16, 2017 / Page IV-11
substances that do not have screening values (see Section IV.E). The remediator could
also evaluate VI using the SSS by developing toxicity values or utilizing published
information (§ 250.605).
Table IV-6 summarizes data collection conditions for VI screening and how to apply the
POAs. Methods for VI screening are described in Sections IV.F and IV.G and in
Table IV-7. Appendix IV-A describes the methodology for developing the screening
values. SSS screening is explained in Section IV.K.
3.
Guidelines for Evaluating VI Using a Combination of Standards
The VI pathway can be evaluated under the SHS, the SSS 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 IV-1 through IV-5 were designed to be used only when
attaining the SHS. However, under specific circumstances, adjusted SHS VI screening
values can be used when evaluating VI under the site-specific standard. See
Section IV.K.4 for additional detail on using screening values under the SSS.
The VI pathway must be assessed to satisfactorily attain the SHS for soil and
groundwater (see 25 Pa. Code § 250.312(a)). Under the SHS, a remediator cannot
evaluate the VI pathway without also evaluating soil and/or 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, for instance, evaluate soil under the SHS and
groundwater under the SSS then separately evaluate VI entirely under the SSS. This is
permissible because the SSS evaluates individual exposure pathways and Act 2 considers
VI to be an exposure pathway, not an environmental medium. Under the SSS, a risk
assessment is needed to evaluate the VI pathway if pathway elimination is not being
used. The SHS does not evaluate individual exposure pathways separately so
remediators cannot evaluate the VI pathway under the SHS if soil and groundwater are
being evaluated under the SSS. The remediator may also choose to evaluate VI for each
substance and medium using the process for the corresponding standard. Figure IV-2
shows how to treat substances independently with a combination of standards.
When using VI modeling under the SHS, the desired output is a predicted indoor air
concentration (Appendix IV-B). This modeled concentration should be used in the
evaluation of VI by comparing it to the associated indoor air screening value. The J&E
model (U.S. EPA, 2004) also calculates risk values which should not be used for SHS
evaluations. Use of risk calculations to evaluate VI is considered to be a risk assessment,
which is a tool to be used under the SSS 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.

261-0300-101 / DRAFT December 16, 2017 / Page IV-12
Figure IV-2: Representative Process to Evaluate VI with a Combination of Standards

261-0300-101 / DRAFT December 16, 2017 / Page IV-13
If the remediator uses the site-specific standard to evaluate the VI pathway, either solely
or under a combination of standards, the SSS VI process described in Section IV.K
should be used.
The following matrix illustrates the assessment needs for addressing the VI pathway
using a combination of standards.
VI Assessment Needs When Using a Combination of Standards
Act 2 Standard
Used to Address
Soil and
Groundwater
VI Evaluation Tools
Use
Screening
Values in
Tables IV-
1–5
Use 1/10
Screening
Values in
Tables IV-
1–5*
Modeling
Risk
Assessment
Mitigation
with EC
(i.e.,
pathway
elimination)
Remediation
Statewide Health
Standard (SHS)
?
?
?
?
Site-Specific
Standard (SSS)
?
?
?
?
?
Combination of
Standards**
?
?
?
?
?
?
*
When defining a potential VI source, a one-tenth adjustment to soil and groundwater screening values is not
required for the SSS.
**
Some media and/or substances may attain the SHS while others may attain the SSS.

261-0300-101 / DRAFT December 16, 2017 / Page IV-14
D.
Preferential Pathway Evaluation
A preferential pathway is a feature that increases the rate of vapor migration between a source
and an inhabited building (see definition in Section IV.B). DEP defines two classes of
preferential pathways.
An external preferential pathway
is a channel or conduit that allows for
a greater vapor flux than ordinary diffusion through vadose zone soil (Figure IV-3).
Significant
foundation openings
are breaches in the building foundation and basement walls that may
enhance the entry of subsurface vapors. (Typical cracks, gaps, and utility line penetrations are
not generally significant foundation openings; see Section IV.D.2.) The presence and
significance of these features should be identified whenever possible during CSM development
(Section IV.C.1.). When building access is not possible, other preferential pathway assessment
and investigation techniques should be used, when available, to complete the CSM. Guidance
for assessing and investigating external preferential pathways and significant foundation
openings is provided in Sections IV.D.1. and IV.D.2., respectively. Guidance for using
screening values when external preferential pathways and significant foundation openings are
present is provided in Sections IV.F and IV.G.
Some recognized instances of preferential pathways include the following.
An external preferential pathway that does not penetrate the building foundation.
External preferential pathways can impact buildings through VI even if they do not
penetrate the building foundation. If the external preferential pathway is not fully
enclosed, vapors can migrate into a building via typical cracks and gaps in building
foundations. An example is permeable backfill material (e.g., gravel or sand) around a
utility line close to a building slab or a basement wall. The vapors can travel through the
backfill material and then migrate through soil into the building via typical cracks and
gaps in the building foundation. If a utility trench is backfilled with native soil, then it is
unlikely to act as a preferential pathway. Another example is a drain line or cracked
sewer pipe (Guo
et al.
, 2015). Water will travel through the line, but vapors can escape
through cracks in the pipe and can migrate through soil into a building. Natural features
such as open bedrock fractures could also transport vapors near a building.
A conduit (external preferential pathway) that enters the building.
This is when a
utility line itself, not the backfill material, acts as a conduit for vapors. For example,
liquid- and vapor-phase contamination can enter breaks in sewer and drain lines,
permitting vapors to pass into buildings through failed plumbing components (Jarvela
et
al.
, 2003; Pennell
et al.
, 2013).
A significant foundation opening without an external preferential pathway.
In this
case, vapors migrate by diffusion through soil from the source to the building. All
building foundations have minor cracks and gaps, but if there is a large opening—such as
a dirt basement floor—then that opening will amplify the flux of vapors into indoor air.
Sealing the opening(s) (e.g., pouring a concrete slab over the dirt floor) can eliminate the
preferential pathway.
A combination of an external preferential pathway with a significant opening.
For
example, vapors may migrate through gravel backfill around a utility line and then flow
through a gap where the line penetrates the foundation. Sealing the gap would resolve
VI through the significant opening but not the role of the external preferential pathway.

261-0300-101 / DRAFT December 16, 2017 / Page IV-15
Reasonable effort should be made to determine whether external preferential pathways or
significant foundation openings are present. It is recommended that remediators discuss how
they plan to evaluate external preferential pathways and significant foundation openings with
their Department Project Officer to ensure that all parties agree on the proposed approach.
As described later in this guidance, a preferential pathway may be eliminated by appropriate site
remediation or mitigation actions.
1.
External Preferential Pathways
Utility corridors and pipes are potential external preferential pathways common to most
sites (U.S. EPA, 2015a, Sections 5.4, 6.3.2). When a preferential pathway is external to a
building, the proximity distances to a source area (as described in Section IV.E) are
insufficient to eliminate the source from consideration because proximity 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 when an external preferential pathway is present
(Figure IV-3). Heightened attention should be paid to external preferential pathways
which may contain SPL.
For a subsurface feature that is external to a building, the following conditions allow it to
be excluded as an external preferential pathway:
Soil and groundwater contamination exceeding VI screening values is at least
30 horizontal or five vertical feet from the feature, and any SPL is at least
30 horizontal or 15 vertical feet from the feature; OR
The feature is at least five feet away from the building foundation.
To exclude a feature as a preferential pathway, soil between the subsurface feature and
the building foundation within the separation distances specified above 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 within the overall 15-foot minimum
separation.) As an example, consider an area of contaminated soil exceeding screening
values which is beyond the horizontal proximity distance from a building. If a high-
permeability backfilled trench passes through the soil contamination and near the
building, but 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.
Figure IV-3 illustrates the evaluation of a potential external preferential pathway
associated with a release from an underground storage tank (UST). (The assessment
described here is not limited to USTs or petroleum hydrocarbons.) As shown in the
separate map and side views, the distribution of contamination relative to the preferential
pathway is important both horizontally and with depth. Zone A, shown in both views, is
the volume of contaminated media identified in the site characterization. In the map
view, the contamination in Zones B and C exceeds the soil and/or groundwater screening
values, but these areas are beyond the horizontal proximity distance from the building.

261-0300-101 / DRAFT December 16, 2017 / Page IV-16
However, Zone C represents the portion of contamination that exceeds screening values
that is within 30 feet horizontally of the potential preferential pathway.
The side view of Figure IV-3 shows that some of the contamination is above the water
table and some is below it. Zone D represents the contamination that exceeds soil and
groundwater screening values but is greater than five feet below the potential preferential
pathway, so the groundwater and soil contamination in Zone D is not of concern for
vapor migration into the feature. Zone E, which is a portion of Zone C in unsaturated
soil, is within five feet vertically of the feature, which means vapors from Zone E could
enter the potential preferential pathway. Since the feature is separated by less than
five feet from the building foundation, the feature is considered to be a preferential
pathway with Zone E as a potential VI source. In this case, further VI assessment is
required.
Figure IV-3: The Role of an External Preferential Pathway in the VI Evaluation
If a utility line trench is backfilled with native, low-permeability soil and the feature is
intact (i.e., there is no evidence of the ability of groundwater or soil vapors to enter the
pipe) then the feature is not considered to be an external preferential pathway. The
Department does not expect remediators to prove that underground features do not have
high-permeability backfill or are intact. However, if there is an indication that these
conditions exist, then remediators should evaluate the feature further. For example, if the

261-0300-101 / DRAFT December 16, 2017 / Page IV-17
underground feature is the trench for a large diameter water line which is likely to be
backfilled with gravel, it should be considered to be a potential external preferential
pathway. If the underground feature is a small diameter fiber optic line, it is likely to
have native soil backfill and the remediator could work under the assumption that it is not
an external preferential pathway.
The Department recommends a progressive approach to evaluating external preferential
pathways. The investigation can include sampling at the source (soil, groundwater, SPL,
near-source soil gas), within the preferential pathway (soil gas or vapor), under the
building (sub-slab soil gas), and within the building (indoor air). If a series of buildings
is associated with one underground feature (e.g., a sewer line servicing multiple buildings
along a street), then the buildings closest to the vapor source should be evaluated first. If
it is determined that there are no VI concerns with the first building along the potential
preferential pathway, then it is generally not necessary to evaluate the rest of the
buildings along the line since they are increasingly farther away from the source.
Access to buildings is not always necessary for the evaluation of external preferential
pathways because much of the pertinent information relates to their condition outside of
the building. Examples of non-intrusive investigation techniques include a visual
inspection of the exterior of the property for utility line entry points, an inspection of
nearby streets and sidewalks for signs of underground utility lines and vaults, a
Pennsylvania One Call notification, or a review of building plans.
The following recommendations pertain to assessing and screening external preferential
pathways. (See Appendix IV-C, Figure IV-C-2 for an illustration.) The evaluation is
described in terms of VI screening, but the remediator may also use the data with
appropriate attenuation factors (Appendix IV-A) to carry out an SSS risk assessment
(Section IV.K.5.). This is not a checklist of required evaluations; rather, if any of the
following items is satisfied such that screening values or risk thresholds are not exceeded,
then other items do not need to be examined.
Use of soil and groundwater screening values
– Contamination in the source
area may be screened using soil and groundwater screening values unless SPL is
present or contaminated groundwater enters the preferential pathway.
Groundwater that is within a preferential pathway may be screened with used
aquifer MSCs.
Use of indoor air modeling
– The default model for predicting indoor air
concentrations (see Appendix IV-B) using soil, groundwater, or soil gas data may
be used in the absence of an external preferential pathway. The default model
should not be used if an external preferential pathway is present because this
model is based on the diffusion of vapors through soil.
Use of near-source soil gas screening values
– If contaminated groundwater or
SPL does not enter the preferential pathway, then near-source soil gas samples
may be collected in the source area and the data screened with near-source soil
gas screening values. Near-source soil gas data can also be screened against sub-
slab soil gas screening values if an external preferential pathway or significant
foundation opening is present or if a potential VI source is less than five feet

261-0300-101 / DRAFT December 16, 2017 / Page IV-18
below foundation level (see Section IV.G). This option is not available if the
source is less than five feet below grade.
Soil gas sampling within a preferential pathway
– Soil gas samples may be
collected in the preferential pathway (e.g., within trench backfill) between the
source area and the building. These are not near-source soil gas samples
(Section IV.G). They should be collected at a depth of at least 5 feet if the area is
not paved and satisfy the other soil gas sampling criteria in this guidance
(Table IV-6, Appendix IV-C). The data may be screened with sub-slab screening
values.
Sampling within a sewer line
– If the preferential pathway is a sewer line or
similar enclosed conduit that contains contamination, then the remediator may
consider analysis of SPL, water, and vapor in the line. Flows and concentrations
are likely to be highly variable, and there can be other sources of contamination in
sewer lines. For these reasons, such sampling can be used as an informational
line of evidence but not for screening.
Sub-slab sampling
– If the preferential pathway does not penetrate the
foundation (e.g., trench backfill without a significant opening or a conduit that
does not enter the building), then sub-slab samples through the foundation may be
obtained (Section IV.G). This data may be screened with sub-slab screening
values.
Sealed utility penetrations
– If the preferential pathway does penetrate the
building, then the remediator should examine potential entry routes to indoor air.
The basement or slab should be inspected for significant openings; foundation
openings can be sealed (see Section IV.D.2.). If vapors travel within a sewer or
drain line, then plumbing components could be inspected for integrity and
repaired if necessary. Sampling should be performed to demonstrate that the
pathway is incomplete, and this may require indoor air sampling.
Indoor air sampling
– Indoor air may be sampled at any time when there is an
external preferential pathway, and the data may be screened with indoor air
screening values (Section IV.G).
2.
Significant Foundation Openings
Significant openings internal to a building’s structure, such as a dirt basement floor, may
enhance vapor entry (U.S. EPA, 2015a, Sections 2.3, 6.5.2). Typical cracks, gaps, and
utility line penetrations on their own are generally not considered to be significant
openings. In fact, all foundations, even new ones, will have these minor openings which
will permit the ingress of some vapors if a potential VI source or an external preferential
pathway comes close to a building foundation. Common foundation openings such as
sealed sumps, French drains, and floor drains are not necessarily significant openings.

261-0300-101 / DRAFT December 16, 2017 / Page IV-19
Significant foundation openings will have any one of the following characteristics.
The combined area of openings in the foundation surface is more than
five percent of the total foundation surface area (Appendix IV-A).
There are direct indications of contaminant entry into the building through
openings, such as seepage of SPL or contaminated groundwater, chemical odors,
or elevated readings on a field screening instrument.
An opening is connected directly to an external preferential pathway; for instance,
a gap around a utility line penetration permits unimpeded vapor entry from the
permeable backfill in the utility line trench.
The most effective way to evaluate a building for significant foundation openings is to
gain access to the building and visually inspect the foundation and basement walls for
utility penetrations and overall foundation condition. Remediators should try to access
buildings whenever possible so that they can get the best possible information when
evaluating significant foundation openings. However, visual inspections are not always
possible. Sometimes property owners do not grant access to buildings. It is also possible
for finished basements to have coverings on walls and floors (e.g., paneling, carpet, etc.)
making openings difficult to see. If the remediator cannot gain access to a building to
inspect for significant foundation openings, there are several assessment options
presented below that do not require building access.
The Department recommends sealing significant foundation openings to inhibit the
pathway (U.S. EPA, 2008, Section 3.2). Proper sealing should be done with durable
materials as a long-term solution such that the former openings are no more transmissive
to vapors than the rest of the foundation. Although sumps, when dry, are not generally
considered to be significant openings, if a sump contains contaminated groundwater it
may need to be sealed. Sealing openings is a building repair and is therefore not
considered an activity and use limitation.
The recommendations listed below concern the assessment and screening of significant
foundation openings. (See Appendix IV--C, Figure IV-C-3 for an illustration.) The
evaluation is described in terms of VI screening, but the remediator may also use the data
with appropriate attenuation factors (Appendix IV-A) to carry out an SSS risk assessment
(Section V.K.5.). Unless otherwise noted, the methods below cannot be used if
contaminated soil, groundwater, or SPL is present within the building. This is not a
checklist of required evaluations; rather, if any of the following items is satisfied such
that screening values or risk thresholds are not exceeded, then other items do not need to
be examined.
Options to assess significant foundation openings that do not require building access
include the following.
If there is no external preferential pathway, then the horizontal proximity
distances discussed in Section IV.E are applicable to the potential VI source.
Vertical proximity distances do not apply because they are based on attenuation
across an intact slab.

261-0300-101 / DRAFT December 16, 2017 / Page IV-20
Soil data may be screened using generic soil-to-groundwater numeric values.
Groundwater data may be screened with used aquifer MSCs. These screening
values are acceptable even if contaminated soil or groundwater is present inside
the building.
Near-source soil gas samples may be collected in the source area. This data
should be screened with sub-slab screening values or modeled.
Modeling of soil, groundwater, or near-source soil gas data may be performed by
assuming that no slab is present as a conservative scenario (as described in
Appendix IV-B).
Options to assess significant foundation openings when building access is available and
possible include the following.
Sub-slab soil gas samples may be obtained if the building does not have a dirt
floor. Sub-slab data should be screened with indoor air screening values.
If foundation openings are sealed, then soil and groundwater data may be
screened with standard screening values, near-source soil gas data may be
screened with near-source soil gas screening values, and sub-slab soil gas data
may be screened with sub-slab screening values (Sections IV.F and IV.G).
Indoor air screening can be used at any time, even when contaminated soil,
groundwater, or SPL is present within the building.

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E.
Use of Proximity Distances
The remediator may use horizontal and vertical proximity distances from existing or planned
future inhabited buildings to identify potential VI sources (Figure IV-6). 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
postremediation 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 IV-4).
Areas of SPL and areas predicted to exceed the screening values in a fate-and-transport analysis
are identified. If there is no SPL present or soil or groundwater screening values are not
exceeded within these proximity distances, then no VI sources are present to address under the
SHS.
If there is contamination both within a proximity distance (e.g., Figure IV-4) and near a potential
preferential pathway (e.g., Figure IV-3), then the remediator evaluates each area of
contamination separately. There may be potential VI sources in both locations. The process
outlined in Figure IV-6 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
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 five 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
hydrocarbons listed on the Petroleum Short List from the LRP Technical Guidance Manual.
(Note that 1,2-dibromoethane, 1,2-dichloroethane, and MTBE are not petroleum hydrocarbons.)
Petroleum substances are either aliphatic or aromatic compounds. Aliphatic compounds are
composed of straight-chained, branched, or cyclic compounds and can be saturated (alkanes) or
unsaturated (alkenes, alkynes, and others). Aromatic compounds have one or more conjugated,
benzene or heterocyclic rings within their structures.
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, 2013, 2015b; 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

261-0300-101 / DRAFT December 16, 2017 / Page IV-22
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 IV-C
for a recommended methodology). For instance, in the case of a large SPL plume or a large
building overlying SPL, oxygen may be depleted and the 15-foot vertical proximity distance
might not be protective for VI.
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 exceedance, 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 five 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 contaminated groundwater plume or unsaturated zone area of soil
petroleum screening value exceedance, then there is adequate distance for biodegradation to
occur to reduce the vapor concentrations to acceptable levels. The minimum vertical proximity
distance is 15 feet for petroleum SPL, at least five 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 NAPL). If neither the horizontal
nor vertical proximity condition is met, the remediator must evaluate VI further.
An example of the application of proximity distances is shown in Figure IV-4. (The assessment
described here is not limited to USTs or petroleum hydrocarbons.) Zone A is the area of
contamination identified in the site characterization. Zones B and C include groundwater
contamination that exceeds screening values, and Zone G represents the horizontal proximity
distance from Zones B and C. Zone C is the area within the horizontal proximity distance from
the existing building, so it is the only portion of groundwater contamination that could pose a
VI problem. Therefore, Zone C is a potential VI source, at least for non-petroleum substances,
that requires additional assessment.

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Figure IV-4: Use of Proximity Distances to Evaluate Potential VI Sources
The vertical proximity distance can be applied to the petroleum portion of the contamination. If
this release contains only petroleum, then the contamination in groundwater is not of VI concern
because groundwater is entirely below the vertical proximity distance line. The brown and
orange zones below the tank represent contaminated soil that exceeds screening values, with the
brown zone being the portion of contaminated soil that is above the vertical proximity distance.
However, the contaminated soil 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.

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F.
Soil and Groundwater VI Screening
This section describes the development and application of soil and groundwater screening values
to properly collected characterization and attainment data. Remediators may choose from the
following soil and groundwater screening options.
Soil or Groundwater Screening
Additional Considerations
Soil concentrations < SVSOIL
Not available if SPL is present or if there is a
significant foundation opening that has not been
sealed.
Soil concentrations < generic soil-
to-groundwater numeric value
Available with significant foundation openings.
Not available if SPL is present.
Groundwater concentrations
< SVGW
Not available if groundwater is less than five feet
below foundation level, if SPL is present, if
contaminated groundwater enters an external
preferential pathway, or if there is a significant
foundation opening that has not been sealed.
Groundwater concentrations <
used aquifer groundwater MSC
Available if groundwater is less than five feet
below foundation level, if contaminated
groundwater enters an external preferential
pathway, or if there is a significant foundation
opening. Not available if SPL is present.
When evaluating VI for the Converted Residential Category using the generic soil-to-
groundwater numeric values or the used aquifer groundwater MSCs, the non-residential values
should be used since the current use of the property, and therefore the exposure parameters, are
non-residential. A summary of screening value restrictions and the reasoning for the restrictions
is provided in Figure IV-9.
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 they are the Act 2 groundwater MSCs, and (2) at depths
greater than or equal to five feet below the foundation they are the values provided in
Table IV-1. The soil VI screening values are provided in Table IV-2. The derivation of
these values is explained in Appendix IV-A. Table IV-6 describes important conditions
for collecting soil and groundwater data to be used for VI screening.
The groundwater VI screening values (SVGW) 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 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.).

261-0300-101 / DRAFT December 16, 2017 / Page IV-25
The soil VI screening values (SVSOIL) 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.
If a preferential pathway or significant foundation opening restricts the use of soil or
groundwater screening values (Section IV.D), the remediator may still utilize
groundwater MSCs and generic soil-to-groundwater numeric values for VI screening
(unless SPL is present). These values may be applied even if contamination is present
within the building (e.g., contaminated groundwater in a sump or contaminated soil in a
dirt basement floor).
2.
Soil and Groundwater Screening Methods
The presence of residual SPL in soil or mobile SPL in groundwater prevents the use of
soil or groundwater screening values (Figure IV-5). (Although Figure IV-5 illustrates a
UST, the criteria indicated are not limited to tank cases or petroleum hydrocarbon
contaminants.) Screening values for soil and groundwater may be used to address VI for
buildings beyond the appropriate horizontal proximity distance from SPL (Figure IV-6).
If there is a preferential pathway or a significant foundation opening, then additional
restrictions may apply (Section IV.D). The remainder of this subsection assumes that
neither SPL nor preferential pathways prevent the use of soil and groundwater screening
values. Potential sampling locations are illustrated in Appendix IV-C, Figures IV-C-1-3.
For purposes of screening soil and groundwater data to evaluate the VI 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 25 Pa. Code § 250.701(c).
VI can be addressed by screening either characterization data or postremediation 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 IV-4). Important conditions for screening are
listed in Table IV-6. Among these are that groundwater must be sampled at or near 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 soil and
groundwater characterization data are below MSCs without remediation being performed,
then the site characterization data may be used for VI screening (Tables IV-6 and IV-7).
No potential VI source exists if the applicable characterization data does not exceed soil

261-0300-101 / DRAFT December 16, 2017 / Page IV-26
and groundwater VI screening values (SVSOIL, SVGW). If the characterization data
exceed MSCs but the remediator intends to pursue the SHS (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 IV-7). Note, however, that
the groundwater data evaluated for VI is within the horizontal proximity distance from
current or planned future inhabited buildings, not just at the point of compliance. For
example, when at least eight consecutive quarters of groundwater attainment data have
been collected, the remediator may apply the 75%/10x test to monitoring wells on the
property and the 75%/2x test for off-site monitoring wells for VI screening
(§ 250.707(b)(2)(i)). Fewer than eight consecutive quarters of data may be screened for
no exceedances with Department approval pursuant to § 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 are 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 AUL restricting construction of future inhabited
buildings.

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Figure IV-5: Effect of Separate Phase Liquid on the Applicability of Screening Values

261-0300-101 / DRAFT December 16, 2017 / Page IV-28
G.
Alternative VI Assessment Options
The purpose of the VI assessment options is to gather and evaluate enough information to
adequately determine whether a potential VI source is present that must be addressed under the
SHS. Remediators may choose from the following alternative assessment options.
Alternative Assessment Option
Additional Considerations
Near-source soil gas
concentrations < SVNS
Not available if contaminated groundwater or SPL
enters a preferential pathway, if there is a
significant foundation opening, if an external
preferential pathway penetrates the building
foundation, or if a potential VI source is less than
five feet below foundation level.
Near-source soil gas
concentrations < SVSS
Available for preferential pathways and significant
foundation openings, and available for a potential
VI source less than five feet below foundation
level, but not if it is less than five feet below grade.
Sub-slab soil gas concentrations
< SVSS for existing buildings
Not available if an external preferential pathway
penetrates the building foundation or if there is a
significant foundation opening that has not been
sealed.
Sub-slab soil gas concentrations
< SVIA for existing buildings
Available if a preferential pathway penetrates the
foundation or there is a significant foundation
opening.
Indoor air concentrations
< SVIA at existing buildings
No restrictions.
Vapor intrusion modeling using
acceptable input parameters
Not available for soil or groundwater where an
external preferential pathway or SPL is present.
Not available for near-source soil gas if an external
preferential pathway is present.
A summary of screening value restrictions and the reasoning for the restrictions is provided in
Figure IV-9.
1.
Soil Gas and Indoor Air Screening Values
The near-source soil gas screening values (SVNS) are provided in Table IV-3, the sub-
slab soil gas screening values (SVSS) in Table IV-4, and the indoor air screening values
(SVIA) in Table IV-5. The derivation of these values is explained in Appendix IV-A.
Table IV-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 IV-C.
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.

261-0300-101 / DRAFT December 16, 2017 / Page IV-29
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. Screening near-source
soil gas data against near-source soil gas screening values is an option when a preferential
pathway does not penetrate the building foundation (Section IV.D). 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. As a
result, screening sub-slab soil gas data against sub-slab screening values cannot be done
in the presence of a preferential pathway that penetrates the building foundation
(Section IV.D). 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 not attributable to soil or groundwater
contamination. This can lead to false positive indoor air detections which increases
uncertainty in VI investigations. The likelihood of false negative indoor air detections is
relatively low. If the remediator suspects that there are indoor sources of vapor
contamination at the site, indoor air sampling is not recommended.
2.
Soil Gas and Indoor Air Screening Methods
Near-source soil gas, sub-slab soil gas, and indoor air data may be acquired during the
site characterization phase or following soil or groundwater remediation. VI sampling
requirements and statistical tests are not specified in 25 Pa. Code 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 sub-slab soil gas, and indoor air
sampling and at least two near-source soil gas sample locations at the source. Potential
sampling locations are illustrated in Appendix IV-C, Figures IV-C-1-3.
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).
These decisions are made on a case-by-case basis. Other important conditions for
collecting data for the VI evaluation are listed in Table IV-6 and Appendix IV-C.
The presence of SPL does not prevent the use of near-source soil gas or sub-slab soil gas
screening values (Figure IV-5) unless the SPL has entered an external preferential
pathway or significant opening. Indoor air screening values are available even in

261-0300-101 / DRAFT December 16, 2017 / Page IV-30
circumstances when SPL, an external preferential pathway, and/or a significant opening
are present.
The POA for near-source soil gas is at least five feet below grade (Figure IV-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 Appendix IV-C, Table IV-C-1. 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 (8°C) below the minimum indoor
temperature in the occupied space and when 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. If a building is not heated, then indoor air samples collected at any time of
the year may be used for screening.
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 IV-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 IV-C).
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 sample locations as source
concentrations, vapor entry rates, and indoor ventilation rates will vary across the
structure. If an as-yet undeveloped area is being evaluated, then there will need to be
enough near-source soil gas points to encompass future building construction. Because

261-0300-101 / DRAFT December 16, 2017 / Page IV-31
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.
If the near-source soil gas, sub-slab soil gas, or indoor air characterization data are equal
to or less than the screening values (SV
NS
, SV
SS
, SV
IA
), then no potential VI sources are
present to address under the SHS. (However, be aware of potential restrictions associated
with preferential pathways, as described above.) 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 IV-7). The other option is to select another
assessment or remedial alternative (Figure IV-6). 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
SSS. In this case, the remediator should not collect near-source soil gas samples because
they are farther from the point of exposure.
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 planned 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 (e.g. two rounds of sampling at
four locations or four rounds of sampling at two locations). Sample locations should be
biased toward areas with the greatest expected VI impact. The following soil and
groundwater statistical tests of § 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 test) and two times the screening value beyond
the property boundary (75%/2x test).
As applied in accordance with EPA-approved methods on statistical analysis of
environmental data, as identified in 25 Pa. Code § 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 test 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.

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3.
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
(Appendix B). 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 own set of conservative default input parameters that should be used
when applicable. However, some parameters such as soil type, depth to the source, and
building size can be adjusted to site-specific conditions.
Soil and groundwater data cannot be used for modeling if an external preferential
pathway or SPL is present. In addition, near-source soil gas data may not be modeled
when there is an external preferential pathway. However, near-source data may be
collected above SPL and modeled. The J&E model also may be applied when a building
has significant foundation openings, such as a dirt floor, as described in Appendix B.
For sites that are completely or partially undeveloped, many of the modeling input
parameters will have to be estimated. The remediator can use information from building
plans, if available, and conservative parameter values. A list of input parameters that can
be adjusted based on site conditions is provided in the modeling guidance presented in
Appendix IV-B.
Pennsylvania versions of EPA’s J&E model spreadsheets are available on DEP’s website.
They should be used for Act 2 and storage tank corrective action 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 SHS, 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. The J&E model can calculate risk values, but these
should not be used for SHS evaluations. Use of risk calculations to evaluate VI is
considered to be a risk assessment, which is a tool to be used under the SSS, 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.

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H.
Mitigation and Activity and Use Limitations
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 and
planned future 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 should be installed by
individuals or firms certified by DEP for radon mitigation pursuant to 25 Pa. Code Chapter 240
of the regulations (Pennsylvania DEP, 1997). Standard residential systems do not need to be
designed or approved by a Licensed Professional Engineer. The remediator is not required to
perform indoor air confirmation sampling. Active sub-slab depressurization systems can be
tested by measuring pressure differentials to demonstrate depressurization throughout the slab or
by collecting one or more indoor air samples that do not exceed screening values. The system
should be tested following its installation, if a significant modification or repair is made, after a
change in ownership, or upon request by the Department. Performance and testing guidelines for
these systems are provided in Appendix IV-C, Section IV-C.9.
Other engineering controls that mitigate VI, such as the installation of a vapor barrier, can be
used to prevent VI. Vapor barriers should be designed and manufactured for use in VOC
mitigation. The material should be chemically resistant and have 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.
The following AULs can be used to maintain the attainment of the SHS.
Using mitigation as a means of eliminating or reducing vapor migration
Committing to mitigation (as described below) of currently planned future inhabited
buildings on the property.
Committing to evaluate potential VI sources at the time currently planned future
inhabited buildings are constructed. The results of the evaluation should be submitted to
DEP for review.
Prohibiting construction of basements or future residential and/or nonresidential
inhabited buildings in a specified area of the property where the VI pathway may be
complete.
If there are no plans for future construction of inhabited buildings at the site, the remediator may
still choose to use an AUL to address possible future VI issues. In this case, controls would not
be required to maintain the SHS, but the remediator may wish to have additional protection for

261-0300-101 / DRAFT December 16, 2017 / Page IV-34
unplanned uses. Any combination of the above four conditions may be utilized. For example,
Figure IV-4 depicts the proximity distance evaluation for a current building (Section IV.E).
Groundwater contamination in Zones B and C and the soil contamination zone in orange also
represent potential VI sources at the site if a future inhabited building is constructed within the
applicable proximity distances from these areas. Zone G, indicated by the outer dotted
perimeter, 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 AULs requiring future evaluation if a new
building is constructed, preemptive mitigation of new buildings, or the prohibition of occupied
buildings within Zone G.
As required by the Uniform Environmental Covenants Act (Act 68 of 2007, 27 Pa. C.S.
§§ 6501–6517, “UECA”) and the accompanying regulations (25 Pa. Code Chapter 253),
engineering and institutional controls needed to address the VI pathway in order to demonstrate
attainment of the SHS or SSS are to be in the form of an environmental covenant, unless waived
by DEP. 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.
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

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I.
Remediating and Reassessing 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 postremediation data is evaluated following the process illustrated in Figure IV-6 and
described in Sections IV.F and IV.G.
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.

261-0300-101 / DRAFT December 16, 2017 / Page IV-36
J.
Addressing 25 Pa. Code Chapter 250 Requirements
The final step in the process flowchart on Figure IV-6 is to address the requirements of 25 Pa.
Code Chapter 250 with respect to VI. This step is necessary to demonstrate compliance with the
SHS in order to receive liability protection under Act 2. The submitted report should include a
description of the CSM for VI with a preferential pathway assessment. The flowchart endpoint
can be reached in the following three ways, and compliance should be documented in either the
FR (Chapter 250) or the site characterization and/or remedial action completion reports
(Chapter 245):
Soil and Groundwater Screening.
The remediator may screen soil and groundwater
concentration data within proximity distances of existing or planning buildings. 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 planned 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 planned
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 IV-B 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 IV-C)
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 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 SSS to address VI, then the remediator should follow the process and
reporting described in Section IV.K.

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K.
Evaluating the VI Pathway Under the Site-Specific Standard
1.
Overview
A remediator may perform a SSS VI evaluation for one of three reasons:
The remediator has selected the SSS for substances of VI concern in soil and/or
groundwater;
Soil and groundwater attain the SHS MSCs, but the VI pathway is not
satisfactorily addressed by the SHS VI assessment process described previously in
this guidance;
The remediator wishes to evaluate VI for substances to which the SHS process
cannot be applied, such as mercury, cyanide, or organics without inhalation
toxicity values.
The SSS VI evaluation process shares many elements with the SHS process, but the
screening values are not the same and a human health risk assessment is an option. The
SSS VI process is outlined in Figure IV-7. It is important to note that the purpose of
Figure IV-7 is to illustrate how all of the steps in the VI evaluation process under the SSS
fit together. Figure IV-7 should not be used as your 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 SSS are:
Develop the CSM and assess the presence of preferential pathways.
Identify potential VI sources from exceedances of SHS soil and groundwater
screening values within proximity distances and/or the occurrence of SPL.
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 using activity and use limitations.
Remediate the soil and/or groundwater contamination and reassess the pathway.
Address the 25 Pa. Code Chapter 250 SSS 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 SHS VI screening values presented in this guidance are based on a carcinogenic
target risk level of 10
-5
and a non-carcinogenic hazard quotient of 1.0. These screening

261-0300-101 / DRAFT December 16, 2017 / Page IV-38
values are not appropriate for use in risk assessments being performed under the SSS
because the SHS target risk levels may not be sufficiently conservative to account for
cumulative risks to receptors from multiple contaminants and/or multiple pathways.
However, screening can be performed under the SSS for VI according to Section IV.K.4
below.
2.
Preferential Pathway Evaluation
The remediator must assess potential preferential pathways and significant foundation
openings as part of the SSS CSM development. The presence of a preferential pathway
or significant opening may limit the use of proximity distances, screening values, and
modeling.
The conditions listed in Section IV.D to identify and evaluate preferential pathways and
significant openings also apply under the SSS. Specifically, contamination in soil and
groundwater that exceeds SHS screening values within 30 horizontal and five vertical
feet of a preferential pathway constitutes a potential VI source (Figure IV-3). Acceptable
soil or soil-like material is qualified by no exceedances of SHS soil screening values.
However, soil, groundwater, near-source soil gas, sub-slab, and indoor air sample data
should be screened with appropriate site-specific screening values as described in
Section IV.K.4.
3.
Use of Proximity Distances
The remediator may utilize proximity distances to identify potential VI sources, as
described in Section IV.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 five feet below a building foundation and
petroleum SPL is at least 15 feet below a building foundation, they are not considered to
be a potential VI source. These vertical proximity distances must encompass acceptable
soil or soil-like material.
Potential VI sources are established by the presence of SPL and exceedances of SHS soil
and groundwater screening values within the applicable horizontal proximity distance.
Appropriate site-specific screening values are explained in Section IV.K.4. For
petroleum vertical proximity distances to apply, there must be acceptable soil or soil-like
material (i.e., no exceedances of SHS soil screening values) in the upper five feet.
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 SSS. This step in the evaluation allows substances to be eliminated
prior to performing a risk assessment. Samples should be collected pursuant to the
guidance in Table IV-6 and Appendix IV-C. An assessment of external preferential
pathways, significant foundation openings, and the presence of SPL needs to be
performed prior to screening as these are conditions that can limit the use of screening
values.

261-0300-101 / DRAFT December 16, 2017 / Page IV-39
If no limiting conditions exist, then soil and groundwater data may be screened using
appropriate 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 (Section IV.G
and Figure IV-9):
Near-source soil gas screening values are not available if there is a source less
than five feet below the building foundation, if SPL or contaminated groundwater
has entered a preferential pathway, if an external preferential pathway penetrates
the building foundation, or if there is a significant foundation opening. Despite
these limitations, if the potential VI source is at least five feet below grade, then
near-source soil gas data may be screened with sub-slab screening values.
Sub-slab soil gas screening may not be performed if an external preferential
pathway penetrates the building foundation or in the presence of a significant
foundation opening. In those cases, the data may be screened with indoor air
screening values.
The Department permits remediators to define potential VI sources using SHS soil and
groundwater screening values, even if the substances and media will be attaining the SSS.
However, when screening soil or groundwater attainment data to eliminate substances
from a risk assessment, the remediator must use SSS screening values as described
below.
The SHS VI screening values listed in Tables IV-1 through IV-5 may not be used as
is, without adjustment, for SSS screening.
The SHS criteria are based on a 10
-5
target
cancer risk and a 1.0 target hazard quotient, and on groundwater MSCs and soil-to-
groundwater numeric values (Appendix IV-A). Attainment for the SSS is demonstrated
for cumulative risks to receptors from all substances, media, and pathways.
VI evaluations using a combination of standards are discussed in Section IV.C.3.
As illustrated in Figure IV-8, substance-by-substance SSS VI risk screening values can
be determined 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 IV-1 through IV-5, or used aquifer
groundwater MSCs and generic soil-to-groundwater numeric values if limiting
conditions apply (see Section IV.F and Figure IV-9). Reduce each screening
value 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, 2016a). 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 IV-A):

261-0300-101 / DRAFT December 16, 2017 / Page IV-40
Sample Type
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 IV.F.2, and
the methods for near-source soil gas, sub-slab soil gas, and indoor air are provided in
Section IV.G.2. Screening may be applied to characterization and postremediation 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 SSS, the only acceptable screening criterion is no exceedances of the applicable
screening values. Substances that screen out using either one-tenth of the SHS VI
screening values or the EPA RSLs do not need to be included in a VI risk assessment.
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 (25 Pa. Code § 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. For the SSS, the cumulative excess
risk for known or suspected carcinogens may not be greater than 10
-4
and the hazard
index may not exceed one for systemic toxicants (25 Pa. Code § 250.402).
Current toxicity values should be used in a SSS risk assessment (25 Pa. Code § 250.605).
Therefore, if a toxicity value has been updated since the last revision of the SHS
screening values, that new information must be included in a cumulative risk assessment.
This provision is consistent with DEP’s discretion in allowing screening to substitute for
a risk assessment.
VI modeling is one option for SSS risk assessments. DEP’s modeling guidance is
provided in Appendix IV-B. For SSS 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 IV.K.4.

261-0300-101 / DRAFT December 16, 2017 / Page IV-41
Inhalation risks are calculated using standard equations. (See Appendices IV-A
and IV-B)
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/or remedial action completion
reports. Human health risk assessment guidance is found in Section III.H. Screening of
chemicals of concern may follow the methodology described in Section IV.K.4.
6.
Mitigation and Remediation
If site contamination does not screen out using the SSS screening values or the
cumulative risks are excessive, then the remediator may choose to mitigate the VI
pathway or remediate the VI sources. The remediator can also select these options before
screening field data or carrying out a risk assessment. Mitigation and remediation require
submittal of a cleanup plan.
Current and planned future inhabited buildings may be mitigated to eliminate the VI
pathway (Section IV.H). Mitigation measures that prevent the migration of vapor, such
as vapor barriers or sub-slab depressurization systems, are considered to be engineering
controls. The standard mitigation approach is an active sub-slab depressurization system
(U.S. EPA, 2008). Performance and testing guidelines are provided in Appendix IV-C.
Measures taken that limit or prohibit exposure are considered to be institutional controls.
Engineering or institutional controls used to mitigate the VI pathway must be addressed
in the postremediation care plan and must be memorialized in an environmental
covenant.
Remediation of soil and/or groundwater is also an alternative to address the VI pathway
(Section IV.I). Postremediation 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.
7.
Using an OSHA Program to Address VI
VI can be difficult to evaluate when vapors from soil or groundwater sources enter
industrial (or commercial) facilities that use the same chemical(s) in their processes.
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 as an institutional control within
the SSS. The remediator should 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 a hazard

261-0300-101 / DRAFT December 16, 2017 / Page IV-42
communications plan is in place, including the posting of Safety Data Sheets [SDSs;
formerly known as Material Safety Data Sheets (MSDSs)], so 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.
Remediators should not use an OSHA program to evaluate risk from VI in cases where
the regulated substances being evaluated for the VI pathway are not used in the work
place. It is also expected that a quantitative analysis of indoor air data using occupational
screening values will be included in the VI assessment. Data is needed to show that
OSHA worker protection measures are satisfied and also to demonstrate compliance and
attainment of the SSS. If OSHA implementation cannot be documented, then an OSHA
program cannot be used as a means of addressing VI. A checklist is included in
Appendix IV-D to help remediators and reviewers ensure that the OSHA program is
adequately documented. All items on the checklist should be provided to demonstrate
that a complete OSHA program is present to provide protection. Additional guidance
regarding the use of industrial hygiene/occupational health programs to address the VI
pathway can be found in EPA’s
OSWER Technical Guide for Assessing and Mitigating
the Vapor Intrusion Pathway from Subsurface Vapor Sources to Indoor Air
(U.S. EPA,
2015a).
The use of an OSHA program to address VI is an institutional control because it limits
exposure through the implementation of the OSHA requirements. If the future owner
does not use the same chemical(s) in their industrial process as the previous owner and/or
does not fully implement an OSHA program for the same chemical(s), then VI would
need to be reevaluated by the new owner.
8.
Addressing Chapter 250 Requirements
The final step in the process flowchart on Figure IV-7 is to address the requirements of
Chapter 250 with respect to VI. This step is necessary to demonstrate compliance with
the SSS under Act 2. The submitted report should include a description of the CSM for
VI with a preferential pathway assessment. The flowchart endpoint can be reached in the
following four ways. Compliance should be documented in Act 2 (Chapter 250) or
storage tank corrective action (Chapter 245) reports:
Soil and Groundwater Screening.
The remediator may screen soil and
groundwater concentration data within proximity distances to existing or currently
planned inhabited buildings. 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 planned 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 FR 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

261-0300-101 / DRAFT December 16, 2017 / Page IV-43
data satisfy the screening criteria, then no further analysis is necessary. Sampling
locations relative to potential VI sources and existing or planned 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 FR 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 25 Pa.
Code § 250.409 and Section III.H. 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 IV-B.
Mitigation and Activity and Use Limitations.
The remediator may address the
VI pathway by installing a mitigation system or implementing AULs in an
environmental covenant. Submittal of a cleanup plan is required when an
engineering control is used to mitigate the exposure pathway for a current
receptor. 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 IV-C)
and the results described in the report. The conditions to be included in a
covenant to maintain the remedy or eliminate the pathway should also be detailed
in a postremediation care plan. Documentation for mitigation systems and
covenant remedies is provided in the FR 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
SSS or through the SHS process, as appropriate.

261-0300-101 / DRAFT December 16, 2017 / Page IV-44
Figure IV-6: Statewide Health Standard Vapor Intrusion Assessment Process
261-0300-101 / DRAFT December 16, 2017 / Page IV-45
Figure IV-7: Site-Specific Standard Vapor Intrusion Assessment Process
261-0300-101 / DRAFT December 16, 2017 / Page IV-46
Figure IV-8: Process to Determine Site-Specific Standard Vapor Intrusion Screening Values

261-0300-101 / DRAFT December 16, 2017 / Page IV-47
Figure IV-9: Screening Value Use Restrictions

261-0300-101 / DRAFT December 16, 2017 / Page IV-48
L.
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Environmental Science & Technology, 45, 2227-2235.

261-0300-101 / DRAFT December 16, 2017 / Page IV-54
M.
Tables
Table IV-1: Groundwater SHS Vapor Intrusion Screening Values (SV
GW
)
Regulated Substance
CAS No.
Residential
(μg/L)
Type
Nonresidential
(μg/L)
Type
Converted
Residential
(μg/L)
Type
ACETALDEHYDE
75-07-0
5,300
SV
67,000
SV
22,000
SV
ACETONE
67-64-1
37,000,000
SV
470,000,000
SV
160,000,000
SV
ACETONITRILE
75-05-8
75,000
SV
940,000
SV
310,000
SV
ACROLEIN
107-02-8
6.8
SV
86
SV
29
SV
ACRYLAMIDE
79-06-1
3,200,000
SV
120,000,000
SV
41,000,000
SV
ACRYLIC ACID
79-10-7
150,000
SV
1,900,000
SV
650,000
SV
ACRYLONITRILE
107-13-1
110
SV
1,700
SV
560
SV
ALLYL ALCOHOL
107-18-6
1,000
SV
13,000
SV
4,300
SV
AMMONIA
7664-41-7
230,000
SV
2,900,000
SV
960,000
SV
ANILINE
62-53-3
27,000
SV
340,000
SV
110,000
SV
BENZENE
71-43-2
23
SV
350
SV
120
SV
BENZYL CHLORIDE
100-44-7
58
SV
870
SV
290
SV
BETA PROPIOLACTONE
57-57-8
0.012
MSC
0.063
MSC
0.063
MSC
BIPHENYL, 1,1-
92-52-4
91
MSC
970
SV
430
MSC
BIS(2-CHLOROETHYL)ETHER
111-44-4
240
SV
3,600
SV
1,200
SV
BIS(2-CHLORO-ISOPROPYL)ETHER
108-60-1
1,700
SV
25,000
SV
8,500
SV
BIS(CHLOROMETHYL)ETHER
542-88-1
0.0040
SV
0.060
SV
0.020
SV
BROMOCHLOROMETHANE
74-97-5
1,200
SV
15,000
SV
5,000
SV
BROMODICHLOROMETHANE
75-27-4
80
MSC
200
SV
80
MSC
BROMOMETHANE
74-83-9
26
SV
330
SV
110
SV
BUTADIENE, 1,3-
106-99-0
0.39
SV
5.9
SV
2.0
SV
CARBON DISULFIDE
75-15-0
2,000
SV
25,000
SV
8,200
SV
CARBON TETRACHLORIDE
56-23-5
6.0
SV
91
SV
30
SV
CHLORO-1,1-DIFLUOROETHANE, 1-
75-68-3
330,000
SV
1,400,000
Sol.
1,400,000
SV
CHLORO-1-PROPENE, 3- (ALLYL
CHLORIDE)
107-05-1
3.8
SV
48
SV
16
SV
CHLOROBENZENE
108-90-7
760
SV
9,600
SV
3,200
SV
CHLORODIBROMOMETHANE
124-48-1
80
MSC
670
SV
220
SV

261-0300-101 / DRAFT December 16, 2017 / Page IV-55
Regulated Substance
CAS No.
Residential
(μg/L)
Type
Nonresidential
(μg/L)
Type
Converted
Residential
(μg/L)
Type
CHLORODIFLUOROMETHANE
75-45-6
110,000
MSC
540,000
SV
440,000
MSC
CHLOROETHANE
75-00-3
35,000
SV
440,000
SV
150,000
SV
CHLOROFORM
67-66-3
80
MSC
180
SV
80
MSC
CHLOROPRENE
126-99-8
0.16
MSC
0.90
SV
0.83
MSC
CHLOROPROPANE, 2-
75-29-6
230
SV
2,900
SV
970
SV
CRESOL(S)
1319-77-3
20,000,000
Sol.
20,000,000
Sol.
20,000,000
Sol.
CUMENE (ISOPROPYL BENZENE)
98-82-8
1,900
SV
24,000
SV
8,000
SV
CYCLOHEXANE
110-82-7
13,000
MSC
53,000
MSC
53,000
MSC
CYCLOHEXANONE
108-94-1
4,000,000
SV
37,000,000
Sol.
17,000,000
SV
DIBROMO-3-CHLOROPROPANE, 1,2-
96-12-8
0.57
SV
22
SV
7.2
SV
DIBROMOETHANE, 1,2- (ETHYLENE
DIBROMIDE)
106-93-4
2.9
SV
44
SV
15
SV
DIBROMOMETHANE
74-95-3
220
SV
2,800
SV
920
SV
DICHLORO-2-BUTENE, 1,4-
764-41-0
0.42
SV
6.3
SV
2.1
SV
DICHLORO-2-BUTENE, TRANS-1,4-
110-57-6
0.42
SV
6.4
SV
2.1
SV
DICHLOROBENZENE, 1,2-
95-50-1
5,400
SV
69,000
SV
23,000
SV
DICHLOROBENZENE, P-
106-46-7
75
MSC
680
SV
230
SV
DICHLORODIFLUOROMETHANE
(FREON 12)
75-71-8
1,000
MSC
1,000
MSC
1,000
MSC
DICHLOROETHANE, 1,1-
75-34-3
110
SV
1,600
SV
550
SV
DICHLOROETHANE, 1,2-
107-06-2
34
SV
510
SV
170
SV
DICHLOROETHYLENE, 1,1-
75-35-4
300
SV
3,800
SV
1,300
SV
DICHLOROETHYLENE, TRANS-1,2-
156-60-5
600
SV
7,600
SV
2,500
SV
DICHLOROMETHANE (METHYLENE
CHLORIDE)
75-09-2
7,600
SV
95,000
SV
32,000
SV
DICHLOROPROPANE, 1,2-
78-87-5
37
SV
560
SV
190
SV
DICHLOROPROPENE, 1,3-
542-75-6
75
SV
1,100
SV
380
SV
DICYCLOPENTADIENE
77-73-6
0.63
MSC
2.6
MSC
2.6
MSC
DIOXANE, 1,4-
123-91-1
30,000
SV
450,000
SV
150,000
SV
EPICHLOROHYDRIN
106-89-8
930
SV
12,000
SV
3,900
SV
ETHOXYETHANOL, 2- (EGEE)
110-80-5
22,000,000
SV
280,000,000
SV
94,000,000
SV
ETHYL ACETATE
141-78-6
23,000
SV
290,000
SV
98,000
SV

261-0300-101 / DRAFT December 16, 2017 / Page IV-56
Regulated Substance
CAS No.
Residential
(μg/L)
Type
Nonresidential
(μg/L)
Type
Converted
Residential
(μg/L)
Type
ETHYL ACRYLATE
140-88-5
1,100
SV
14,000
SV
4,700
SV
ETHYL BENZENE
100-41-4
700
MSC
860
SV
700
MSC
ETHYL METHACRYLATE
97-63-2
29,000
SV
370,000
SV
120,000
SV
ETHYLENE GLYCOL
107-21-1 420,000,000
SV
1,000,000,000
Sol.
1,000,000,00
0
Sol.
FLUOROTRICHLOROMETHANE
(FREON 11)
75-69-4
2,000
MSC
3,600
SV
2,000
MSC
FORMALDEHYDE
50-00-0
200,000
SV
3,000,000
SV
990,000
SV
FORMIC ACID
64-18-6
69,000
SV
880,000
SV
290,000
SV
FURFURAL
98-01-1
700,000
SV
8,800,000
SV
2,900,000
SV
HEXACHLOROETHANE
67-72-1
31
SV
480
SV
160
SV
HEXANE
110-54-3
1,500
MSC
6,200
MSC
6,200
MSC
HYDRAZINE/HYDRAZINE SULFATE
302-01-2
410
SV
6,200
SV
2,100
SV
METHACRYLONITRILE
126-98-7
5,400
SV
68,000
SV
23,000
SV
METHANOL
67-56-1
41,000,000
SV
510,000,000
SV
170,000,000
SV
METHOXYETHANOL, 2-
109-86-4
3,000,000
SV
38,000,000
SV
13,000,000
SV
METHYL ACRYLATE
96-33-3
4,400
SV
56,000
SV
19,000
SV
METHYL CHLORIDE
74-87-3
53
SV
810
SV
270
SV
METHYL ETHYL KETONE
78-93-3
3,900,000
SV
49,000,000
SV
16,000,000
SV
METHYL HYDRAZINE
60-34-4
320
SV
4,000
SV
1,300
SV
METHYL ISOBUTYL KETONE
108-10-1
1,000,000
SV
13,000,000
SV
4,300,000
SV
METHYL ISOCYANATE
624-83-9
44
SV
550
SV
180
SV
METHYL METHACRYLATE
80-62-6
110,000
SV
1,300,000
SV
450,000
SV
METHYL N-BUTYL KETONE (2-
HEXANONE)
591-78-6
16,000
SV
200,000
SV
66,000
SV
METHYL STYRENE (MIXED
ISOMERS)
25013-15-4
960
SV
12,000
SV
4,000
SV
METHYL TERT-BUTYL ETHER
(MTBE)
1634-04-4
6,300
SV
96,000
SV
32,000
SV
METHYLNAPHTHALENE, 2-
91-57-6
380
SV
4,800
SV
1,600
SV
NAPHTHALENE
91-20-3
100
MSC
1,300
SV
440
SV
NITROBENZENE
98-95-3
1,400
SV
21,000
SV
7,000
SV

261-0300-101 / DRAFT December 16, 2017 / Page IV-57
Regulated Substance
CAS No.
Residential
(μg/L)
Type
Nonresidential
(μg/L)
Type
Converted
Residential
(μg/L)
Type
NITROPROPANE, 2-
79-46-9
3.4
SV
52
SV
17
SV
NITROSODIETHYLAMINE, N-
55-18-5
3.3
SV
120
SV
42
SV
NITROSODIMETHYLAMINE, N-
62-75-9
19
SV
710
SV
240
SV
NITROSO-DI-N-BUTYLAMINE, N-
924-16-3
91
SV
1,400
SV
460
SV
PCB-1221 (AROCLOR)
11104-28-2
3.5
SV
53
SV
18
SV
PCB-1232 (AROCLOR)
11141-16-5
3.6
SV
55
SV
18
SV
PHENOL
108-95-2
34,000,000
SV
84,000,000
Sol.
84,000,000
Sol.
PROPANOL, 2- (ISOPROPYL
ALCOHOL)
67-63-0
1,200,000
SV
16,000,000
SV
5,200,000
SV
PROPYLBENZENE, N-
103-65-1
4,900
SV
52,000
Sol.
21,000
SV
PROPYLENE OXIDE
75-56-9
3,700
SV
56,000
SV
19,000
SV
STYRENE
100-42-5
18,000
SV
220,000
SV
75,000
SV
TETRACHLOROETHANE, 1,1,1,2-
630-20-6
70
MSC
980
SV
330
SV
TETRACHLOROETHANE, 1,1,2,2-
79-34-5
54
SV
820
SV
270
SV
TETRACHLOROETHYLENE (PCE)
127-18-4
110
SV
1,300
SV
440
SV
TETRAHYDROFURAN
109-99-9
26
MSC
130
MSC
130
MSC
TOLUENE
108-88-3
34,000
SV
430,000
SV
140,000
SV
TRIBROMOMETHANE
(BROMOFORM)
75-25-2
2,000
SV
30,000
SV
10,000
SV
TRICHLORO-1,2,2-
TRIFLUOROETHANE, 1,1,2-
76-13-1
63,000
MSC
170,000
Sol.
170,000
Sol.
TRICHLOROBENZENE, 1,2,4-
120-82-1
80
SV
1,000
SV
340
SV
TRICHLOROBENZENE, 1,3,5-
108-70-3
59
SV
740
SV
250
SV
TRICHLOROETHANE, 1,1,1-
71-55-6
12,000
SV
160,000
SV
52,000
SV
TRICHLOROETHANE, 1,1,2-
79-00-5
11
SV
140
SV
48
SV
TRICHLOROETHYLENE (TCE)
79-01-6
9.0
SV
110
SV
38
SV
TRICHLOROPROPANE, 1,2,3-
96-18-4
44
SV
560
SV
190
SV
TRICHLOROPROPENE, 1,2,3-
96-19-5
0.83
SV
10
SV
3.5
SV
TRIETHYLAMINE
121-44-8
2,200
SV
27,000
SV
9,100
SV
TRIMETHYLBENZENE, 1,3,4-
(TRIMETHYLBENZENE, 1,2,4-)
95-63-6
59
SV
750
SV
250
SV
TRIMETHYLBENZENE, 1,3,5-
108-67-8
420
MSC
1,200
MSC
1,200
MSC

261-0300-101 / DRAFT December 16, 2017 / Page IV-58
Regulated Substance
CAS No.
Residential
(μg/L)
Type
Nonresidential
(μg/L)
Type
Converted
Residential
(μg/L)
Type
VINYL ACETATE
108-05-4
18,000
SV
220,000
SV
74,000
SV
VINYL BROMIDE (BROMOETHENE)
593-60-2
2.2
SV
34
SV
11
SV
VINYL CHLORIDE
75-01-4
2.0
MSC
52
SV
17
SV
XYLENES (TOTAL)
1330-20-7
10,000
MSC
12,000
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 December 16, 2017 / Page IV-59
Table IV-2: Soil SHS 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
4,700
SV
1,200
SGN
ACETONITRILE
75-05-8
1.5
SGN
9.6
SV
6.0
SGN
ACROLEIN
107-02-8
0.00047
SGN
0.0020
SGN
0.0020
SGN
ACRYLAMIDE
79-06-1
37
SV
2,400
SV
480
SV
ACRYLIC ACID
79-10-7
1.9
SV
40
SV
8.1
SV
ACRYLONITRILE
107-13-1
0.010
SGN
0.051
SGN
0.051
SGN
ALLYL ALCOHOL
107-18-6
0.0068
SV
0.14
SV
0.029
SV
AMMONIA
7664-41-7
360
SGN
360
SGN
360
SGN
ANILINE
62-53-3
1.3
SV
27
SV
5.4
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
0.0056
SV
0.14
SV
0.028
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
SAT
10,000
SAT
CHLOROETHANE
75-00-3
5.4
SGN
26
SGN
26
SGN

261-0300-101 / DRAFT December 16, 2017 / Page IV-60
Regulated Substance
CAS No.
Residential
(mg/kg)
Type
Nonresidential
(mg/kg)
Type
Converted
Residential
(mg/kg)
Type
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
310
SV
6,600
SV
1,300
SV
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
84
SV
1,800
SV
350
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
0.0013
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
0.076
SGN
1.5
SV
0.30
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
0.23
SV
5.9
SV
1.2
SV
EPICHLOROHYDRIN
106-89-8
0.042
SGN
0.27
SV
0.17
SGN
ETHOXYETHANOL, 2- (EGEE)
110-80-5
190
SV
4,100
SV
820
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

261-0300-101 / DRAFT December 16, 2017 / Page IV-61
Regulated Substance
CAS No.
Residential
(mg/kg)
Type
Nonresidential
(mg/kg)
Type
Converted
Residential
(mg/kg)
Type
ETHYL METHACRYLATE
97-63-2
10
SGN
43
SGN
43
SGN
ETHYLENE GLYCOL
107-21-1
3,000
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
34
SV
12
SGN
FORMIC ACID
64-18-6
0.40
SV
8.9
SV
1.8
SV
FURFURAL
98-01-1
5.2
SV
110
SV
22
SV
HEXACHLOROETHANE
67-72-1
0.56
SGN
0.56
SGN
0.56
SGN
HEXANE
110-54-3
1,400
SGN
5,600
SGN
5,600
SGN
HYDRAZINE/HYDRAZINE SULFATE
302-01-2
0.0025
SV
0.063
SV
0.013
SV
METHACRYLONITRILE
126-98-7
0.069
SGN
1.2
SV
0.24
SV
METHANOL
67-56-1
270
SV
5,600
SV
1,100
SV
METHOXYETHANOL, 2-
109-86-4
18
SV
380
SV
75
SV
METHYL ACRYLATE
96-33-3
1.0
SGN
5
SGN
5
SGN
METHYL CHLORIDE
74-87-3
0.38
SGN
0.38
SGN
0.38
SGN
METHYL ETHYL KETONE
78-93-3
76
SGN
1,100
SV
210
SV
METHYL HYDRAZINE
60-34-4
0.0020
SV
0.041
SV
0.0082
SV
METHYL ISOBUTYL KETONE
108-10-1
51
SGN
210
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
6.4
SGN
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
1.4
SV
0.28
SGN
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
0.000039
SV
0.0025
SV
0.00049
SV
NITROSODIMETHYLAMINE, N-
62-75-9
0.00015
SV
0.0094
SV
0.0019
SV

261-0300-101 / DRAFT December 16, 2017 / Page IV-62
Regulated Substance
CAS No.
Residential
(mg/kg)
Type
Nonresidential
(mg/kg)
Type
Converted
Residential
(mg/kg)
Type
NITROSO-DI-N-BUTYLAMINE, N-
924-16-3
0.017
SGN
0.25
SV
0.078
SGN
PCB-1221 (AROCLOR)
11104-28-2
0.18
SGN
0.83
SGN
0.83
SGN
PCB-1232 (AROCLOR)
11141-16-5
0.14
SGN
0.7
SGN
0.7
SGN
PHENOL
108-95-2
380
SV
7,900
SV
1,600
SV
PROPANOL, 2- (ISOPROPYL
ALCOHOL)
67-63-0
15
SV
300
SV
61
SV
PROPYLBENZENE, N-
103-65-1
400
SGN
1,700
SGN
1,700
SGN
PROPYLENE OXIDE
75-56-9
0.052
SGN
1.1
SV
0.24
SGN
STYRENE
100-42-5
24
SGN
79
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
SAT
10,000
SAT
10,000
SAT
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
7.4
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

261-0300-101 / DRAFT December 16, 2017 / Page IV-63
Regulated Substance
CAS No.
Residential
(mg/kg)
Type
Nonresidential
(mg/kg)
Type
Converted
Residential
(mg/kg)
Type
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 December 16, 2017 / Page IV-64
Table IV-3: Near-Source Soil Gas SHS Vapor Intrusion Screening Values (SV
NS
)
Regulated Substance
CAS No.
Residential
(μg/m
3
)
Nonresidential
(μg/m
3
)
Converted
Residential
(μg/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

261-0300-101 / DRAFT December 16, 2017 / Page IV-65
Regulated Substance
CAS No.
Residential
(μg/m
3
)
Nonresidential
(μg/m
3
)
Converted
Residential
(μg/m
3
)
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
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

261-0300-101 / DRAFT December 16, 2017 / Page IV-66
Regulated Substance
CAS No.
Residential
(μg/m
3
)
Nonresidential
(μg/m
3
)
Converted
Residential
(μg/m
3
)
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
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

261-0300-101 / DRAFT December 16, 2017 / Page IV-67
Regulated Substance
CAS No.
Residential
(μg/m
3
)
Nonresidential
(μg/m
3
)
Converted
Residential
(μg/m
3
)
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
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 December 16, 2017 / Page IV-68
Table IV-4: Sub-Slab Soil Gas SHS Vapor Intrusion Screening Values (SV
SS
)
Regulated Substance
CAS No.
Residential
(μg/m
3
)
Nonresidential
(μg/m
3
)
Converted
Residential
(μg/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

261-0300-101 / DRAFT December 16, 2017 / Page IV-69
Regulated Substance
CAS No.
Residential
(μg/m
3
)
Nonresidential
(μg/m
3
)
Converted
Residential
(μg/m
3
)
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
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

261-0300-101 / DRAFT December 16, 2017 / Page IV-70
Regulated Substance
CAS No.
Residential
(μg/m
3
)
Nonresidential
(μg/m
3
)
Converted
Residential
(μg/m
3
)
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
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

261-0300-101 / DRAFT December 16, 2017 / Page IV-71
Regulated Substance
CAS No.
Residential
(μg/m
3
)
Nonresidential
(μg/m
3
)
Converted
Residential
(μg/m
3
)
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
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 December 16, 2017 / Page IV-72
Table IV-5: Indoor Air SHS Vapor Intrusion Screening Values (SV
IA
)
Regulated Substance
CAS No.
Residential
(μg/m
3
)
Nonresidential
(μg/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

261-0300-101 / DRAFT December 16, 2017 / Page IV-73
Regulated Substance
CAS No.
Residential
(μg/m
3
)
Nonresidential
(μg/m
3
)
CHLOROPROPANE, 2-
75-29-6
100
440
CRESOL(S)
1319-77-3
630
2,600
CUMENE (ISOPROPYL BENZENE)
98-82-8
420
1,800
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

261-0300-101 / DRAFT December 16, 2017 / Page IV-74
Regulated Substance
CAS No.
Residential
(μg/m
3
)
Nonresidential
(μg/m
3
)
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
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

261-0300-101 / DRAFT December 16, 2017 / Page IV-75
Regulated Substance
CAS No.
Residential
(μg/m
3
)
Nonresidential
(μg/m
3
)
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
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 December 16, 2017 / Page IV-76
Table IV-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.
Sample at or near the water table.
Monitoring well screens cross the water table.
The wetted length of the well screen should be no more than 10 feet.
If the depth to water below the foundation is less than 5 feet then MSC-based
screening values should be used.
Acceptable soil or soil-like material exists between the water table and the
building foundation.
No SPL is present.

261-0300-101 / DRAFT December 16, 2017 / Page IV-77
Sample
Conditions for VI Data Collection
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 IV-C.
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 IV-C.
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 (8°C) below
the minimum indoor temperature of the occupied space.
Refer to Appendix IV-C.

261-0300-101 / DRAFT December 16, 2017 / Page IV-78
Table IV-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) of the regulations may be utilized
for vapor intrusion soil screening (e.g., 75%/10x test).

261-0300-101 / DRAFT December 16, 2017 / Page IV-79
Characterization Data
Vapor Intrusion Screening Conditions
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 25 Pa.
Code §§ 250.702, 250.704, and 250.707(b)(2)(i) of the
regulations may be utilized for vapor intrusion groundwater
screening (e.g., 75%/10x test on the property and 75%/2x test
beyond the property boundary).
Fewer than eight rounds of data may be screened with DEP
approval pursuant to 25 Pa. Code § 250.704(d) of the
regulations. 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 found
at 25 Pa. Code § 250.707(b)(2)(ii) of the regulations 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 December 16, 2017 / Page IV-80
Table IV-7: Application of Statewide Health Standard Vapor Intrusion Screening Criteria (cont.)
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 is 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 planned 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 test) and two times the screening value beyond the
property boundary (75%/2x test).
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.
* The use of screening values may be restricted due to the presence of SPL, external preferential pathways, or significant
foundation openings. See Sections IV.F and IV.G and Figure IV-9 for additional information on screening value use.

261-0300-101 / DRAFT December 16, 2017 / Page IV-81
APPENDICES

261-0300-101 / DRAFT December 16, 2017 / Page IV-82
Appendix IV-A: Methodology for Developing SHS Vapor Intrusion Screening Values
DEP has calculated screening values (SVs) for regulated substances of VI concern for use with the SHS.
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 (α). An attenuation factor is the
ratio between the contaminant concentration in indoor air and the equilibrium soil gas concentration in
the unsaturated zone or sub-slab area (α ≡ 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
POA.
As there are distinct attenuation factors for residential (α R) and nonresidential (α 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 (α 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 IV-1-5 of the VI Guidance. They will be updated
periodically using current scientific information when the 25 Pa. Code Chapter 250 MSCs are revised,
consistent with the 25 Pa. Code § 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 IV-A-1. DEP has not published VI SVs for most of these
chemicals. SHS VI evaluations are not available for substances without SVs. The remediator
may choose to evaluate VI using the SSS for these chemicals. In addition, DEP does not
consider the polycyclic aromatic hydrocarbons (PAHs) in Table IV-A-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 (U.S. EPA, 2016b). These two substances have similar chemical and
toxicological characteristics.
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 RSLs and in the VISL Calculator (U.S. EPA,
2014a, 2016c). SVs for systemic toxicants (SV
IA(nc)
) and carcinogens (SV
IA(c)
) are calculated in
units of micrograms per cubic meter (μg/m
3
).

261-0300-101 / DRAFT December 16, 2017 / Page IV-83
For systemic toxicants (non-carcinogens) the indoor air SV is:
SV
IA(nc)
=
THQ×RfC
i
×AT
nc
×(365
days
yr
)×(24
hr
day)
ET×EF×ED
×
1,000
μg
mg
For carcinogens, the indoor air SV is:
SV
IA(c)
=
TR×AT
c
×(365
days
yr
)×(24
hr
day)
IUR×ET×EF×ED
For substances classified as mutagens, except for vinyl chloride and trichloroethylene, the
residential carcinogenic indoor air SV is:
SV
IA(c,m,R)
=
TR×AT
c
×(365
days
yr
)×(24
hr
day)
IUR×ET×EF×AED
For vinyl chloride, the residential carcinogenic indoor air SV is:
SV
IA(c,vc,R)
=
TR
IUR×ET×EF×ED
AT
c
×(365
days
yr
)×(24
hr
day)
+ IUR
For trichloroethylene, the residential carcinogenic indoor air SV is:
SV
IA(c,TCE,R)
=
TR×AT
c
×(365
days
yr
)×(24
hr
day)
(IUR
k
×AED + IUR
l
×ED)×ET×EF
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 nonresidential indoor air carcinogenic SVs for mutagens are determined using the non-
mutagenic equation SV
IA(c)
given above.
The variables and exposure factors in the above equations are defined in Table IV-A-2. Certain
conditions are explained in § 250.307(h) of the regulations.
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 IV-A-5 herein).

261-0300-101 / DRAFT December 16, 2017 / Page IV-84
Table IV-A-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]