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Prepared Under Contract to Nicor Gas

Bloomington Manufactured Gas Plant Site 1319 Half Street/Bloomington Housing Authority Properties

Amendment to the Remediation Objectives Report and Remedial Action Plan

Prepared January 2017

Burns & McDonnell 1431 Opus Place

Downers Grove, IL 60515-1164

Bloomington MGP Site – 1319/BHA Properties ii ROR/RAP Amendment

ACRONYMS AND ABBREVIATIONS

1319/BHA properties 1319 Half Street property and a portion of the Bloomington Housing Authority property

bgs below ground surface BMcD Burns & McDonnell. cm/sec centimeters per second COC constituent of concern IAC Illinois Administrative Code Illinois EPA Illinois Environmental Protection Agency LWBU lower water bearing unit NFR No Further Remediation ROR/RAP Remediation Objectives Report/Remedial Action Plan SRP Site Remediation Program TACO Tiered Approach to Corrective Action Objectives UWBU upper water bearing unit

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Bloomington MGP Site – 1319/BHA Properties ES-1 ROR/RAP Amendment

EXECUTIVE SUMMARY

This Amendment to the March 2015 Illinois Environmental Protection Agency (Illinois EPA) approved Remediation Objectives Report/Remedial Action Plan – 1319 Half Street/Bloomington Housing Authority Properties (1319/BHA properties ROR/RAP) (Burns & McDonnell [BMcD] 2015a) and associated Response to Illinois EPA Comments (BMcD 2015b) presents a Tier 3 further evaluation of the indoor inhalation exposure route and an updated groundwater ingestion exposure route evaluation, remediation objectives and remedial actions. This ROR/RAP Amendment has been prepared in accordance with the Tiered Approach to Corrective Action Objectives (TACO) as defined in Chapter 35 of the Illinois Administrative Code (IAC), Part 742, and the requirements of the Illinois Site Remediation Program (SRP), 35 IAC, Part 740. The indoor inhalation exposure route was evaluated further under Tier 3 for the compounds and analytes that appear in the SRP target compounds and analytes list to establish remediation objectives that do not require an institutional control. The Tier 3 further evaluation of the indoor inhalation exposure route indicates that the exposure route cannot be eliminated at the 1319/BHA properties and will be evaluated through post-remediation water table sampling to demonstrate compliance with the established Tier 3 remediation objectives. The groundwater ingestion exposure route was evaluated for the Bloomington MGP site and surrounding properties in the Groundwater Remediation Objectives Report (BMcD 2016). Groundwater in shallow monitoring wells located within the 1319/BHA properties have exceedances of remediation objectives; therefore, the groundwater ingestion exposure route cannot be eliminated. Post-remediation groundwater samples will be collected to demonstrate compliance with the Tier 1 Class I groundwater remediation objectives. As presented in the Illinois EPA-approved ROR/RAP, remedial action is appropriate. The updated evaluations presented in this ROR/RAP Amendment do not result in a change to the overall remedial action planned to achieve the remediation objectives for the 1319/BHA properties. The remediation objectives are intended to eliminate exposure to constituents of concern and the remedial actions are expected to result in a comprehensive No Further Remediation letter based on the unrestricted residential property classification, as identified in Subpart F of 35 IAC, Part 740.

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Bloomington MGP Site – 1319/BHA Properties TC-1 ROR/RAP Amendment

TABLE OF CONTENTS

1.0 INTRODUCTION ............................................................................................... 1-1 2.0 TIER 3 FURTHER EVALUATION OF THE INDOOR INHALATION

EXPOSURE ROUTE ......................................................................................... 2-1 2.1 DEVELOPMENT OF TIER 3 REMEDIATION OBJECTIVES ................. 2-1 2.2 APPLICATION OF TIER 3 REMEDIATION OBJECTIVES .................... 2-3

3.0 UPDATED GROUNDWATER INGESTION EXPOSURE ROUTE EVALUATION ................................................................................................... 3-1

4.0 SUMMARY OF REMEDIATION OBJECTIVES ................................................ 4-1 5.0 UPDATED REMEDIAL ACTIONS .................................................................... 5-1 6.0 REFERENCES .................................................................................................. 6-1

Tables

Table 1 Tier 3 Screening: Indoor Inhalation Exposure Route—Groundwater Table 2 Summary of Groundwater Ingestion Exposure Route Screening Table 3 Soil Remediation Objectives Table 4 Groundwater Remediation Objectives

Figures

Figure 1 Site Layout Map Figure 2 Water Table Sample Location Map Figure 3 Indoor Inhalation Exceedance Map Figure 4 Groundwater Ingestion Exceedance Location Map Figure 5 Post-Remediation Monitoring Well Location Map

Appendix

Appendix A Tier 3 Remediation Objectives for the Indoor Inhalation Exposure Route

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Bloomington MGP Site – 1319/BHA Properties 1-1 ROR/RAP Amendment

1.0 INTRODUCTION This Amendment to the March 2015 Illinois Environmental Protection Agency (Illinois EPA) approved Remediation Objectives Report/Remedial Action Plan – 1319 Half Street/Bloomington Housing Authority Properties (1319/BHA properties ROR/RAP) (Burns & McDonnell [BMcD] 2015a) and associated Response to Illinois EPA Comments (BMcD 2015b) presents a Tier 3 further evaluation of the indoor inhalation exposure route and an updated groundwater ingestion exposure route evaluation. This ROR/RAP Amendment has been prepared in accordance with the Tiered Approach to Corrective Action Objectives (TACO) as defined in Chapter 35 of the Illinois Administrative Code (IAC), Part 742, and the requirements of the Illinois Site Remediation Program (SRP), 35 IAC, Part 740. The 1319/BHA properties are located adjacent to the northern boundary of the former Bloomington MGP site, separated by Half Street. The 1319 Half Street property is an 0.11 acre property acquired by Nicor Gas in 2004 and located at the intersection of Half Street and Hinshaw Avenue. The property is a vacant and partially fenced lot. The BHA property occupies 0.75 acres along Half Street and Hinshaw Avenue along the eastern boundary of the 1319 Half Street property. The BHA property is also a vacant and partially fenced lot with trees along its northern boundary. These two properties have been historically only used as residential properties as indicated by available historical documentation. The northwest portion of the BHA property (BHA Northwest) has been excavated up to 15 feet below ground surface (bgs) and backfilled with imported clean clay and topsoil. A Comprehensive No Further Remediation (NFR) Letter dated May 12, 2011 was received from the Illinois EPA for the BHA Northwest property. Figure 1 presents the layout of the properties. The geology on the properties was characterized during previous investigations at the property. The following stratigraphic units, listed in descending order, were identified: fill; silty clay; silty sand; and clay till. The following describes each stratigraphic unit. The initial soil unit on the 1319/BHA properties consists of previously disturbed fill material (mostly silt, silty clay, small gravels, sand, coal, cinders, brick and occasional wood pieces). The fill unit ranges from 0 to 10 feet bgs. The silty clay unit consists of discontinuous deposits of the Richland Loess. Where encountered, the Richland Loess underlies the fill and consists of silty clay, silt and clayey silt and varies in thickness from 1 to 8.5 feet beneath the 1319/BHA properties. The silty clay consists mainly of dark yellowish Brown to dark olive Gray in color with minor amounts of black mottling. The amount of sand present generally increased towards the bottom of the unit. The silty sand unit consists of discontinuous deposits of the Henry Formation deposits. Where encountered, the Henry Formation underlies the fill or silty clay and consists of silts, sands, and some


gravel, and varies in thickness from 0.2 to 7 feet beneath the 1319/BHA properties. The granular deposits consist mainly of dark brown to gray clayey silt with sand, and gray silty sand with some gravel. The clay till unit consists of the Wedron and Glasford Formations and generally underlies the silty sand unit. The Wedron Formation below the 1319/BHA properties was a brownish-gray to gray silty clay with trace sand and some gravel. The top of the clay till beneath the 1319/BHA properties was encountered at depths ranging from 7.5 feet bgs to 15 feet bgs. At the base of the Wedron Formation is an organic rich silt lens consistent with the Robein silt that represents the boundary between the Wedron and Glasford Formations. The top of the Glasford Formation is located at depths between 68 and 85 feet bgs. Two principal water-bearing units lie beneath the Bloomington MGP site and surrounding properties including the 1319/BHA properties. The first water-bearing unit encountered is the upper water-bearing unit (UWBU). Groundwater in the UWBU is generally encountered approximately 5 to 15 feet bgs and the depth to groundwater on the properties was measured at depths ranging from 2.65 feet to 9.2 feet during the latest round of water table sampling. The UWBU ranged from a few inches to 4 feet thick. The geometric mean hydraulic conductivity of the UWBU was determined to be 3.0 x 10-3 centimeters per second (cm/sec). Groundwater flow direction within the UWBU is generally to the northwest. Groundwater flow is well-defined within the study area and is discussed in the Groundwater Investigation Report (BMcD 2016a). The lower water-bearing unit (LWBU) is encountered within the sand and gravel layer in the upper part of the Glasford Formation generally encountered at depths starting at between 68 to 85 feet bgs and varies in thickness from 2.5 to 5 feet. The mean hydraulic conductivity of the LWBU is 2.15 x 10-4 cm/sec. Groundwater flow direction within the LWBU is generally to the northwest. A clay confining layer separates the two water bearing units and is approximately 45 feet thick across the study area. Groundwater within the UWBU and LWBU are Class I Potable Resources.

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2.0 TIER 3 FURTHER EVALUATION OF THE INDOOR INHALATION EXPOSURE ROUTE

TACO specifies that use of the Tier 1 remediation objectives for the indoor inhalation exposure route requires the implementation of an institutional control requiring future buildings on the property to be constructed with a full concrete slab-on-grade or a full concrete basement floor and walls. Therefore, the indoor inhalation exposure route was further evaluated under Tier 3 to determine whether an institutional control is necessary for the 1319/BHA properties. 2.1 DEVELOPMENT OF TIER 3 REMEDIATION OBJECTIVES The Little, Daisey, and Nazaroff (1992) model for vapor intrusion was used to calculate Tier 3 remediation objectives for the 1319/BHA properties. This model conservatively assumes that no concrete slab or basement floor and walls are present to inhibit the advection of soil gas into the building. A detailed presentation of the calculation of Tier 3 remediation objectives is presented in Appendix A. Tier 3 indoor inhalation remediation objectives were developed for the compounds and analytes that appear on the SRP target compounds and analytes lists (SRP, Appendix A, Tables A through D) and the TACO indoor inhalation volatiles list (TACO, Appendix A, Table J). As outlined in the TACO Tier 3 requirements (35 IAC 742.935 (c) and (e)), the following site-specific information is presented to support development of Tier 3 groundwater remediation objectives. Scaled map of the area, showing all buildings and man-made pathways (current and planned) The layout of the 1319/BHA properties is depicted on Figure 1. No buildings are currently present on the properties. Potential manmade preferential pathways currently include buried utility trenches and the concrete slab foundation of the former small, wood-framed house on the 1319 Half Street property. As presented in the Illinois EPA-approved ROR/RAP, remedial actions will include excavation of soil to depths ranging from 10 feet below ground surface (bgs) to 18 feet bgs, to meet unrestricted residential remediation objectives. In the process of excavation, the concrete slab foundation and buried utility trenches will be removed. Current extent and modeled migration of contamination The extent of constituents of concern (COCs) in soil is well-defined and is described in the ROR/RAP. To meet the soil remediation objectives outlined in the ROR/RAP, remedial action (consisting of soil removal) is planned. The extent of COCs in groundwater is also well-defined and is described in the Groundwater Remediation Objectives Report (BMcD 2016b) for the Bloomington MGP site and surrounding properties. The soil remedial actions proposed for various properties are expected to result in reduced constituent concentrations in the UWBU.


Geology, including soil types and parameters and the thickness of the capillary fringe The Illinois EPA-approved ROR/RAP presents an evaluation of the geology of the 1319/BHA properties, based on soil probes and soil borings advanced during previous investigations. In summary, the stratigraphic units generally present on the 1319/BHA properties are: fill; silty clay; silty sand; and clay till. The Tier 3 indoor inhalation remediation objectives were calculated using TACO default soil and capillary fringe parameters (TACO, Appendix C, Table M) that were used by Illinois EPA to develop Tier 1 indoor inhalation remediation objectives. These values are appropriate and conservative for each soil type present at the 1319/BHA properties. Depth to groundwater (including seasonal variation) and flow direction The Illinois-EPA approved ROR/RAP presents an overview of the hydrogeologic conditions at the 1319/BHA properties. The upper water-bearing unit flow in general is to the northwest; however, directly beneath the 1319/BHA properties groundwater flows locally to the west. Some seasonal and year-to-year variation in depth to groundwater has been observed. The shallowest depth to water measured at the 1319/BHA properties was 2.65 feet bgs in the most recent round of water table sampling in September 2014 and was used for the development of the Tier 3 indoor inhalation groundwater remediation objectives. Location of soil gas sampling points and discussion of soil gas sampling procedures No soil gas samples have been collected at the 1319/BHA properties. The shallow water table, with a measured depth to water of 2.65 feet bgs, presents potential challenges for collection of soil gas samples at a minimum depth of 3 feet as required by TACO. Results and locations of groundwater sampling events Water table samples were collected from four locations positioned across the 1319/BHA properties. Location SP1121W was placed near soil probes SP463 and SP455 that were identified as having samples determined to be source material. Location SP1122W was placed near the highest detected benzene concentration in soil at the 1319/BHA properties, in soil probe SP350 (15 to 16 feet bgs), and had visual tar noted in the boring log. The other two locations SP1119W and SP1120W were spaced across the 1319/BHA properties. These water table locations are shown in Figure 2. Other groundwater samples from the 1319/BHA properties were collected from monitoring wells screened below the water table and therefore, were not included for evaluation of the indoor inhalation exposure route. As presented in the Illinois-EPA approved ROR/RAP, the four water table samples were screened against Tier 1 remediation objectives. Benzene exceeded the Tier 1 residential indoor inhalation remediation objective at SP1122W with a concentration of 0.19 mg/L. Analytical results for the other three water table samples were below the Tier 1 remediation objectives.


Mathematical and technical justification for the model proposed, and demonstration that the model was correctly applied Appendix A presents the mathematical and technical justification for use of the Little, Daisey, and Nazaroff (1992) model. It also presents rationale for the model selected and the inputs used, and addresses the transport mechanisms included in the model. 2.2 APPLICATION OF TIER 3 REMEDIATION OBJECTIVES Based on the evaluation of the site-specific conditions, the Tier 3 indoor inhalation residential groundwater remediation objectives were calculated in Appendix A and are acceptable for use at the 1319/BHA properties. These Tier 3 remediation objectives are appropriate for evaluation of a potential future building with an earthen crawl space or earthen floor. Table 1 presents the Tier 3 indoor inhalation screening evaluation for the water table samples collected at the 1319/BHA properties. Benzene exceeded the Tier 3 remediation objective of 0.10 mg/L at one location SP1122W with a concentration of 0.19 mg/L. No other constituents exceeded the Tier 3 indoor inhalation residential groundwater remediation objectives. Figure 3 presents the location of the indoor inhalation exceedance. Since there is an exceedance, the indoor inhalation exposure route cannot be eliminated at the 1319/BHA properties.

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3.0 UPDATED GROUNDWATER EXPOSURE ROUTE EVALUATION This section presents an updated exposure route evaluation of the groundwater ingestion exposure route based on the recently prepared Groundwater Remediation Objectives Report (BMcD 2016b). In the Report, the evaluation of the groundwater component of the groundwater ingestion pathway was completed for the Bloomington MGP site and surrounding properties collectively known as the study area. The evaluations included a Tier 1 evaluation for both the UWBU and LWBU, an area background evaluation for the UWBU and a Tier 3 evaluation for the LWBU. These evaluations resulted in the development of remediation objectives for COCs at the study area in the UWBU and the elimination of the LWBU from further evaluation. To evaluate groundwater collected from monitoring wells, exposure point concentrations (EPCs) were developed for COCs as presented in the Groundwater Investigation Report (BMcD 2016a). Table 2 presents a summary of the monitoring wells on the 1319/BHA properties that are located within the UWBU along with EPCs for each COC in groundwater screened against remediation objectives. Figure 4 presents the shallow monitoring wells that had exceedances of the Tier 1 groundwater remediation objectives. Groundwater concentrations exceeded the Class I groundwater remediation objectives at the 1319/BHA properties; therefore, the direct groundwater ingestion component of the Class I groundwater ingestion exposure route cannot be eliminated.

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4.0 SUMMARY OF REMEDIATION OBJECTIVES As presented in the Illinois EPA-approved ROR/RAP and as updated in this Amendment, remediation objectives were established for the 1319/BHA properties based on the presence of source material and the evaluations of the soil ingestion, soil inhalation, soil migration to groundwater, groundwater ingestion and the indoor inhalation exposure routes. The soil remediation objectives were established in the Illinois EPA-approved ROR/RAP and are presented in Table 3 for the COCs established for the properties. The groundwater remediation objectives have been established and are presented in Table 4. In summary, the updated evaluations do not result in a change to the specific measures to be taken to achieve the remediation objectives for the 1319/BHA properties as follows:

• Remove soil that contains source material. • Remove all surface soil (0 to 3 feet bgs). • Remove subsurface soil that exceeds remediation objectives for the soil ingestion and soil outdoor

inhalation exposure pathways for a residential property and construction workers. • Remove subsurface soil that exceeds remediation objectives for the soil migration to groundwater

exposure pathway. Post remediation monitoring wells will be installed in the UWBU to demonstrate groundwater remediation objectives have been met for both the groundwater ingestion and indoor inhalation exposure routes. These remediation objectives are intended to eliminate exposure to constituents of concern at the1319/BHA properties and to obtain a No Further Remediation (NFR) letter based on the unrestricted residential property classification, as identified in Subpart F of 35 IAC 740.

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5.0 UPDATED REMEDIAL ACTIONS To address the remediation objectives, remedial actions will include the following main components as presented in the Illinois EPA-approved ROR/RAP:

• Site preparation; • Waste characterization; • Ambient air monitoring; • Excavation, stockpiling, off-site disposal of soil, and backfilling; • Confirmation sampling; • Management of decontamination water, potential stormwater, infiltrating groundwater and

run-on/run-off; and • Site restoration.

In order to demonstrate compliance with the groundwater remediation objectives, post-remediation groundwater samples will be collected upon completion of remedial activities. Post-remediation monitoring wells will be installed at five locations across the properties, two upgradient, one in the center, and two downgradient as shown in Figure 5. The wells will be placed to intersect the water table and to monitor the UWBU and two quarterly rounds of confirmation groundwater samples will be collected at each location and sent to an accredited analytical laboratory. Results will be compared to the established remediation objectives for both the groundwater ingestion and the indoor inhalation exposure routes. The first round of samples will be collected once post-remediation groundwater levels have stabilized.

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6.0 REFERENCES Burns & McDonnell (BMcD), 2015a. Remediation Objectives Report/Remedial Action Plan – 1319 Half

Street/Bloomington Housing Authority Properties, Bloomington Manufactured Gas Plant Site. BMcD, 2015b. Letter Response to Illinois EPA Comments on the Remediation Objectives

Report/Remedial Action Plan – 1319 Half Street/Bloomington House Authority Properties, Bloomington Manufactured Gas Plant Site.

BMcD, 2016a. Groundwater Investigation Report, Bloomington Manufactured Gas Plant Site. BMcD, 2016b. Groundwater Remediation Objectives Report, Bloomington Manufactured Gas Plant Site. Illinois Administrative Code (IAC), 2004. Title 35: Environmental Protection, Subtitle G: Waste

Disposal, Chapter I: Pollution Control Board, Subchapter f: Risk Based Cleanup Objectives, Part 740, Site Remediation Program.

IAC, 2013. Title 35: Environmental Protection, Subtitle G: Waste Disposal, Chapter I: Pollution Control

Board, Subchapter f: Risk Based Cleanup Objectives, Part 742, Tiered Approach to Corrective Action Objectives.

Little, J.C.; Daisey, J.M.; and Nazaroff, W.W., 1992. Transport of subsurface contaminants into

buildings: an exposure pathway for volatile organics. Environmental Science and Technology vol. 26, pages 2058-2066.

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TABLES

ROR/RAP AMENDMENT BLOOMINGTON MGP SITE – 1319/BHA PROPERTIES

Bloomington MGP Site—1319/BHA Properties Page 1 of 1 ROR/RAP Amendment

Table 1Tier 3 Screening: Indoor Inhalation Exposure Route - Groundwater

ROR/RAP AmendmentBloomington MGP Site -- 1319/BHA Properties

Tier 3 Sample Location and Date/ConcentrationIndoor Inhalation SP1119W SP1120W SP1121W SP1122W

Remediation 9/23/2014 9/24/2014 9/24/2014 9/24/2014Compound/Analyte Objective WT ~ 5.9' WT ~ 9.2' WT ~ 2.65' WT ~ 8.2'

Volatile Organic Compounds (VOCs) (milligrams per liter [mg/L])Acetone 21,000 0.0050 U 0.0050 U 0.0050 U 0.0050 UBenzene 0.10 0.0025 0.00050 U 0.00050 U 0.19Bromodichloromethane 0.032 0.0010 U 0.0010 U 0.0010 U 0.0010 UBromoform 1.3 0.0010 U 0.0010 U 0.0010 U 0.0010 UBromomethane 1.2 0.0010 U 0.0010 U 0.0010 U 0.0010 U2-Butanone 3,600 0.0050 U 0.0050 U 0.0050 U 0.0050 UCarbon disulfide 61 0.0050 U 0.0050 U 0.0050 U 0.0050 UCarbon tetrachloride 0.063 0.0010 U 0.0010 U 0.0010 U 0.0010 UChlorobenzene 23 0.0010 U 0.0010 U 0.0010 U 0.0010 UChlorodibromomethane 2,700 0.0010 U 0.0010 U 0.0010 U 0.0010 UChloroform 0.040 0.0010 U 0.0010 U 0.0010 U 0.0010 U1,1-Dichloroethane 5,000 0.0010 U 0.0010 U 0.0010 U 0.0010 U1,2-Dichloroethane 0.045 0.0010 U 0.0010 U 0.0010 U 0.0010 U1,1-Dichloroethene 24 0.0010 U 0.0010 U 0.0010 U 0.0010 Ucis-1,2-Dichloroethene 6,400 0.0010 U 0.0010 U 0.0010 U 0.0010 Utrans-1,2-Dichloroethene 4,500 0.0010 U 0.0010 U 0.0010 U 0.0010 U1,2-Dichloropropane 0.11 0.0010 U 0.0010 U 0.0010 U 0.0010 Ucis-1,3-Dichloropropene 0.12 0.0010 U 0.0010 U 0.0010 U 0.0010 Utrans-1,3-Dichloropropene 0.12 0.0010 U 0.0010 U 0.0010 U 0.0010 UEthylbenzene 0.36 0.00050 U 0.00050 U 0.00050 U 0.16Methyl tertiary-butyl ether 2,000 0.0010 U 0.0010 U 0.0010 U 0.0010 UMethylene chloride 88 0.0050 U 0.0050 U 0.0050 U 0.0050 UStyrene 310 0.0010 U 0.0010 U 0.0010 U 0.0025Tetrachloroethene 2.4 0.0010 U 0.0010 U 0.0010 U 0.0010 UToluene 530 0.00050 U 0.00050 U 0.00050 U 0.0131,1,1-Trichloroethane 1,110 0.0010 U 0.0010 U 0.0010 U 0.0010 U1,1,2-Trichloroethane 0.12 0.0010 U 0.0010 U 0.0010 U 0.0010 UTrichloroethene 0.17 0.00050 U 0.00050 U 0.00050 U 0.00050 UVinyl chloride 0.047 0.00050 U 0.00050 U 0.00050 U 0.00050 UXylenes, Total 30 0.0010 U 0.0010 U 0.0010 U 0.038

Semivolatile Organic Compounds (SVOCs) (mg/L)Bis(2-chloroethyl)ether 0.011 0.0016 U 0.0015 U 0.0016 U 0.0017 U2-Chlorophenol 11,000 0.0041 U 0.0037 U 0.0040 U 0.0042 U1,2-Dichlorobenzene 120 0.0016 U 0.0015 U 0.0016 U 0.0017 U1,4-Dichlorobenzene 0.13 0.0016 U 0.0015 U 0.0016 U 0.0017 UHexachlorobenzene 0.0040 0.00041 U 0.00037 U 0.00040 U 0.00042 UHexachlorocyclopentadiene 0.083 0.016 U 0.015 U 0.016 U 0.017 UHexachloroethane 0.13 0.0041 U 0.0037 U 0.0040 U 0.0042 UIsophorone 6,300 0.0016 U 0.0015 U 0.0016 U 0.0017 U2-Methylnaphthalene 25 0.00072 0.00037 U 0.00040 U 0.00042 U2-Methylphenol 4,000 0.0016 U 0.0015 U 0.0016 U 0.0017 UNitrobenzene 0.071 0.00082 U 0.00074 U 0.00080 U 0.00084 Un-Nitrosodi-n-propylamine 0.0055 0.00041 U 0.00037 U 0.00040 U 0.00042 UPhenol 1,900 0.0041 U 0.0037 U 0.0040 U 0.0042 UNaphthalene 0.050 0.0032 0.0011 0.00080 U 0.0141,2,4-Trichlorobenzene 1.4 0.0016 U 0.0015 U 0.0016 U 0.0017 U

Polychlorinated Biphenyls (PCBs) (mg/kg)Aroclor 1232 0.0031 NA NA NA NA

HeptachlorHeptachlor 0.0019 NA NA NA NA

Mercury (mg/L)Mercury 0.060 0.00020 U 0.00020 U 0.00020 U 0.00020 UNotes:1) WT ~ n - Water table encountered at approximately n feet bgs during drilling.2) Remediation objectives are the Tier 3 groundwater remediation objectives calculated in Appendix A for the no-slab scenario with both advection and diffusion.3) U - Compound/analyte not detected. The associated numerical value is the reporting limit.4) NA - Not analyzed in water table samples. However, heptachlor and aroclor 1232 was non-detect in soil samples and aroclor 1232 was non-detect in groundwater samples. These compounds are not an environmental concern at the 1319/BHA Properties.

Bloomington MGP Site - 1319/BHA Properties Page 1 of 1 ROR/RAP Amendment

Table 2Summary of Groundwater Ingestion Exposure Route Screening


Groundwater Sample Location/Exposure Point ConcentrationConstituents of Concern Remediation Objective SMW15 SMW27 SMW33 SMW34 SMW35

Target Compound List (TCL) Volatile Organic Compounds (VOCs) (milligrams per liter [mg/L])Benzene† 0.0006 0.00050 U 0.97 0.011 0.00050 U 0.0010 UEthylbenzene† 0.07 0.00050 U 0.34 0.069 0.00050 U 0.0010 UStyrene† 0.0125 0.0010 U 0.0020 U 0.0010 U 0.0010 U 0.010 UToluene† 0.10 0.00050 U 0.20 0.00050 U 0.00050 U 0.010 U

TCL Semivolatile Organic Compounds (SVOCs) (mg/L)Dibenzofuran 0.007 0.0019 U 0.060 0.0019 U 0.0020 U 0.0019 U2,4-Dimethylphenol† 0.018 0.0093 U 1.2 0.0093 U 0.010 U 0.0094 U2-Methylnaphthalene*† 0.014 0.00047 U 0.26 0.00047 U 0.00051 U 0.00047 U2-Methylphenol† 0.050 0.0019 U 0.32 0.0019 U 0.0020 U 0.0019 UPhenol† 0.0167 0.0047 U 0.012 0.0047 U 0.0051 U 0.0047 UAcenaphthene† 0.070 0.0015 0.049 0.015 0.0010 U 0.00094 UAcenaphthylene*† 0.021 0.00093 U 0.14 0.027 § 0.0010 U 0.00094 UBenzo(a)anthracene 0.00013 0.00012 U 0.00012 U 0.00012 U 0.00013 U 0.00012 UBenzo(b)fluoranthene 0.00018 0.00017 U 0.00017 U 0.00017 U 0.00018 U 0.00017 UBenzo(k)fluoranthene 0.00017 0.00016 U 0.00016 U 0.00016 U 0.00017 U 0.00016 UBenzo(a)pyrene 0.0002 0.00019 U 0.00019 U 0.00019 U 0.00020 U 0.00019 UChrysene 0.012 0.00047 U 0.00047 U 0.00047 U 0.00051 U 0.00047 UDibenzo(a,h)anthracene 0.0003 0.00028 U 0.00019 U 0.00028 U 0.00031 U 0.00028 UFluorene† 0.035 0.00093 U 0.032 J 0.00093 U 0.0010 U 0.00094 UIndeno(1,2,3-cd)pyrene 0.00043 0.00019 U 0.00019 U 0.00019 U 0.00020 U 0.00019 UNaphthalene† 0.023 0.00093 U 0.13 0.00093 U 0.0010 U 0.00094 UPhenanthrene*† 0.021 0.00093 U 0.046 0.00093 U 0.0010 U 0.00094 U

Target Analyte List (TAL) Metals and Cyanide (mg/L)Arsenic†¥ 0.0033 0.0010 U 0.027 0.0044 § 0.0010 U 0.010 UBarium† 0.20 0.029 0.049 0.070 0.066 0.26Cyanide, Total† 0.029 0.34 0.45 0.24 0.13 0.18 **Cyanide, Amenable† 0.029 0.12 NA 0.055 0.037 0.010Notes:1) U - Compound/analyte not detected. The associated numerical value is the reporting limit.2) * - Compound/Analyte is listed in the ''Non-TACO Objectives'' table, Illinois EPA, March 31, 2016.3) Shaded values exceed the remediation objective.4) † - Remediation objective was adjusted for the effects of similar-acting noncarcinogenic chemicals, as calculated in the Groundwater Investigation Report (BMcD 2016).5) § - Determined not to be a Tier 1 exceedance due to weighted-average method for similar-acting noncarcinogenic chemicals, as determined in the Groundwater Investigation Report (BMcD 2016).6) NA - Not Analyzed7) ¥ - Remediation objective for arsenic was taken from 35 IAC 620, October 7, 2013.8) J - Estimated value.9) ** - Corresponding amenable cyanide analytical result is below screening level; therefore, there is no exceedance.

Bloomington MGP Site - 1319/BHA Properties Page 1 of 1 ROR/RAP Amendment

Table 3Soil Remediation Objectives


Constituents of Concern Ingestion Outdoor Inhalation Ingestion Outdoor

Inhalation Volatile Organic Compounds (VOCs) (mg/kg)

Benzene -- 0.8 -- 2.2 0.03 0.03Xylenes (total) -- -- -- 5.6 -- 5.6

Semi-Volatile Organic Compounds (SVOCs) (mg/kg)Dibenzofuran 78 -- -- -- 3 32,4-Dimethylphenol -- -- -- -- 9 92-Methylnaphthalene -- -- -- -- 1.9a 1.94-Methylphenol -- -- -- -- 3.9a 3.9

Polynuclear Aromatic Hydrocarbons (PAHs) (mg/kg)Acenaphthlyene -- -- -- -- 85a 85Benzo(a)anthracene 1.8b -- 170 -- 2 1.8Benzo(b)fluoranthene 2.1b -- 170 -- 5 2.1Benzo(k)fluoranthene 9 -- -- -- 49 9Benzo(a)pyrene 2.1b -- 17 -- 8 2.1Chrysene 88 -- -- -- 160 88Dibenzo(a,h)anthracene 0.42b -- 17 -- 2 0.42Indeno(1,2,3-cd)pyrene 1.6b -- -- -- 14 1.6Naphthalene -- -- -- 1.8 12 1.8Phrenanthrene -- -- -- -- 210a 210

Metals (mg/L)Arsenic 13.0 -- -- -- -- 13.0Lead 400 -- -- -- -- 400Manganese 1,600 -- -- -- -- 1,600Mercury -- 10 -- 0.1 -- 0.1SPLP Aluminum -- -- -- -- 3.5 3.5SPLP Barium -- -- -- -- 2.0 2.0SPLP Cadmium -- -- -- -- 0.005 0.005SPLP Lead -- -- -- -- 0.0075 0.0075SPLP Manganese -- -- -- -- 0.15 0.15SPLP Mercury -- -- -- -- 0.002 0.002Notes:1) a - "Non-TACO Objectives" remediation objective, Illinois EPA, October 30, 2012.2) b - Screening value is from the table of background concentrations for Polynuclear Aromatic Hydrocarbon Chemicals (IAC 2013).3) c - Screening value is from the table of background concentrations for Inorganic Chemicals (IAC 2013).4) -- - Constituent of concern does not exceed pathway remediation objective.

Residential Tier 1 Remediation Objectives

Construction Worker Tier 1 Remediation

Objectives

Soil Migration to GW Tier 1

Remediation Objectives

Remediation Objective

Bloomington MGP Site -- 1319/BHA Properties Page 1 of 1 ROR/RAP Amendment

Table 4Groundwater Remediation Objectives


Groundwater Ingestion Indoor InhalationConstituents of Concern Remediation Objective* Remediation Objective Remediation Objective

Volatile Organic Compounds (milligrams per liter [mg/L])Benzene 0.0006 0.10 0.0006

Ethylbenzene 0.07 -- 0.07Styrene 0.0125 -- 0.0125Toluene 0.10 -- 0.10

Semivolatile Organic Compounds (mg/L)Dibenzofuran 0.007 -- 0.007

2,4-Dimethylphenol 0.018 -- 0.0182-Methylnaphthalene 0.014 -- 0.014

2-Methylphenol 0.050 -- 0.050Phenol 0.0167 -- 0.0167

Acenaphthene 0.070 -- 0.070Acenaphthylene 0.021 -- 0.021

Benzo(a)anthracene 0.00013 -- 0.00013Benzo(b)fluoranthene 0.00018 -- 0.00018Benzo(k)fluoranthene 0.00017 -- 0.00017

Benzo(a)pyrene 0.0002 -- 0.0002Chrysene 0.012 -- 0.012

Dibenzo(a,h)anthracene 0.0003 -- 0.0003Fluorene 0.035 -- 0.035

Indeno(1,2,3-cd)pyrene 0.00043 -- 0.00043Naphthalene 0.023 -- 0.023

Phenanthrene 0.021 -- 0.021Metals (mg/L)

Arsenic 0.0033 -- 0.0033Barium 0.20 -- 0.20

Amenable Cyanide 0.029 -- 0.029Notes:1) * - Groundwater Ingestion remediation objectives established in the Groundwater Remedation Objectives Report (BMcD 2016).2) -- - Constituent of Concern does not exceed pathway remediation objective.

FIGURES

ROR/RAP AMENDMENT BLOOMINGTON MGP SITE – 1319/BHA PROPERTIES

APPENDIX A

TIER 3 REMEDIATION OBJECTIVES FOR THE INDOOR INHALATION EXPOSURE ROUTE

ROR/RAP AMENDMENT

BLOOMINGTON MGP SITE – 1319/BHA PROPERTIES

Bloomington MGP Site – 1319/BHA Properties A-1 ROR/RAP Amendment

APPENDIX A

DEVELOPMENT OF TIER 3 GROUNDWATER REMEDIATION OBJECTIVES FOR THE INDOOR INHALATION EXPOSURE PATHWAY

INTRODUCTION

The Tier 1 remediation objectives (ROs) for the indoor inhalation exposure route presented in TACO, Appendix B, Tables H and I (35 IAC 742) were developed using the Johnson and Ettinger (1991) model (J&E) for subsurface vapor intrusion into buildings. This model includes analytical solutions for phase partitioning and attenuation of constituent vapor concentrations based on physical processes, including diffusion through subsurface soil and advection of soil gas into indoor air. The TACO Tier 1 default model parameters used for calculation of soil gas and groundwater ROs assume that current or future buildings have a full concrete slab-on-grade that is a minimum of 10 centimeters thick, or have full concrete basement floor and walls. Consequently, TACO specifies that use of the Tier 1 ROs for the indoor inhalation exposure route requires the implementation of an institutional control that ensures current or future buildings on the subject property will be constructed to meet these assumed criteria. Additionally, TACO presents Tier 1 ROs for “diffusion only” and “diffusion and advection” scenarios. The “diffusion only” scenario is less conservative, and requires implementation of an additional institutional control requiring any current or future building to be greater than 5 feet vertically and horizontally from contamination. The objective of this Tier 3 evaluation is to develop ROs for groundwater for the indoor inhalation exposure route that do not require the implementation of an institutional control. A mass flux vapor model was used to simulate conditions where the full concrete slab-on-grade or the full concrete basement floor and walls specified in Tier 1 TACO assumptions are absent. Furthermore, this Tier 3 evaluation uses the more conservative “diffusion and advection” scenario. Therefore, the resultant Tier 3 ROs developed do not require the building to be greater than 5 feet away from the contaminants, and they allow the site to be evaluated using only groundwater sample analytical results. As shown in Table A-1, Tier 3 groundwater ROs for residential receptors in buildings constructed with neither a full concrete slab nor a full concrete basement floor and walls (i.e., earthen floor) were calculated.

MODEL SELECTION Three mass flux transport models were outlined in a paper by Little, Daisey, and Nazaroff (1992). One of these models (hereafter referred to as the LDN Model), which describes transport from a planar source and, like the J&E Model, includes diffusion and advection transport mechanisms, was selected to calculate the Tier 3 ROs. Unlike the J&E model, which assumes there is attenuation of soil gas constituent concentrations across a building concrete slab or basement floor and walls, the LDN model conservatively assumes that the entire flux of constituents arriving at the zone near the building is transported into the building. Therefore, the LDN Model, as described in the 1992 paper, is appropriate


to evaluate the scenario where no concrete slab or no basement with concrete floor and walls are present to limit vapor transport into the building (e.g. an earthen floor). The LDN Model is also appropriate for evaluation of other building foundation construction types that may provide little resistance to vapor transport like stone foundations, partial concrete floors, or crawl spaces.

TRANSPORT MECHANISMS: DIFFUSION AND ADVECTION As required in 35 IAC 742.935(c), this Tier 3 evaluation using the LDN Model accounts for diffusive transport from the contaminant source to areas near the building (i.e., the zone of building pressure influence), and then advective transport from the zone of advective influence into indoor air, as summarized below:

• Diffusive transport through soils (i.e., total effective diffusion coefficient, DTeff): The LDN Model

accounts for diffusive transport using the same relationship for diffusion through soils that is used in published mass flux models and by the United States Environmental Protection Agency (USEPA) and Illinois EPA to assess diffusive transport through soils. This relationship for calculation of DT

eff, is consistent with TACO Equations J&E9a and J&E11. The diffusion-related input assumptions used in the TACO Tier 1 default model have been used as input assumptions in the LDN Model.

• Advective transport: The LDN Model accounts for advective transport by conservatively assuming that constituents in soil gas are “swept into the building as fast as they arrive at the zone of influence” (Little, Daisey, and Nazaroff 1992) rather than by using a specific input value for the advective flow rate of soil gas into the building. This assumption is equivalent to assuming a high soil gas advection rate from soil into the building (i.e., assuming an infinite value for the volumetric flow rate of soil gas into the enclosed space [Qsoil]). The Tier 3 ROs are more conservative than the Tier 1 “diffusion and advection” ROs because the assumption for advective transport that all constituents in soil gas are swept into the building is more conservative than the Tier 1 assumption of an empirically established advective flow rate (Qsoil = 83.33 cm3/sec). The Tier 3 ROs should not be compared to the Tier 1 “diffusion only” ROs, which assume that constituents only enter the building by diffusing across the slab and no advective migration occurs at all (Qsoil = 0 cm3/sec).

Because the LDN Model assumes that there are no transport limitations due to the presence of a concrete slab, and instead all subsurface constituents in soil gas are swept into the building, the overall rate of movement of soil gas to indoor air is limited by the rate of diffusion in soil (i.e., diffusion-limited conditions for constituent transport).

INPUT VALUES As shown in Table A-2, the input parameters to the LDN Model were based on TACO default physical setting input values for Tier 1 ROs for parameters that are not related to the slab; however, the following parameters are not included in the LDN Model because no slab is present:

• Area of total cracks (Acrack);


• Slab thickness (Lcrack); • Air-filled porosity for soil in cracks (θa,crack); • Total porosity for soil in cracks (θT,crack); • Water-filled porosity for soil in cracks (θw,crack); and • Floor-wall seam gap (w).

Additionally, as previously discussed, no value was needed for the volumetric flow rate of soil gas into the enclosed space (Qsoil), because the LDN Model assumes that all constituents in soil gas beneath the building floor are swept into the building. This is similar to assuming an infinite value for Qsoil. The water table at the 1319/BHA properties is shallow; therefore, to maintain conservatism, the distance from ground surface to top of contamination (Dsource) value was set to 2.65 feet (80.8 cm). This value is the shallowest groundwater depth measurement at the 1319/BHA properties in the most recent round of water table sampling in September 2014. The calculated ROs are therefore more conservative than would have resulted from using the TACO default Dsource value of 10 feet. As recommended by Illinois EPA, the chemical-specific physical parameters and toxicity parameters used for the calculations were the values in the USEPA Regional Screening Levels (RSLs) – Generic Tables (May 2016).

CALCULATED TIER 3 REMEDIATION OBJECTIVES As listed in Table A-1, ROs were calculated for constituents that are listed in both the Site Remediation Program (SRP) Target Compound List (TCL) (35 IAC 740, Appendix A, Tables A-D) and the TACO Indoor Inhalation Volatile Chemicals List (35 IAC 742, Appendix A, Table J). Risk-based carcinogenic or non-carcinogenic indoor air target concentrations (or both) were calculated as appropriate based on the toxicological effects of each chemical, using the same equations and exposure scenario input values as specified in TACO for Tier 1 and Tier 2 applications. For chemicals exhibiting both carcinogenic and non-carcinogenic effects, the minimum of the carcinogenic and non-carcinogenic target concentrations was selected as the target concentration in indoor air, ROindoor air. Using the input parameters presented in Table A-2, the LDN Model was used to calculate the vapor intrusion attenuation factor (α), which is the ratio of the concentration in indoor air to the concentration in soil gas, for each chemical. The attenuation factors were then used with the Henry’s Law equilibrium constants at the system temperature (H’TS) and a unit conversion from liters (L) to cubic meters (m3) to calculate groundwater ROs:

𝑅𝑅𝑅𝑅𝑔𝑔𝑔𝑔 =𝑅𝑅𝑅𝑅𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖𝑖 𝑎𝑎𝑖𝑖𝑖𝑖

α × 𝐻𝐻𝑇𝑇𝑇𝑇′ × 1000 𝐿𝐿𝑚𝑚3

Table A-3 presents the calculations for groundwater remediation objectives using a Dsource input value of 2.65 feet (80.8 cm). Table A-1 summarizes the Tier 3 ROs that were calculated.


CONCLUSION The LDN Model was used to develop Tier 3 ROs for groundwater at the 1319/BHA properties for the indoor inhalation exposure route for buildings without a concrete slab on grade or full concrete basement floor and walls (i.e. an earthen floor). The resultant Tier 3 ROs facilitate closure of the properties without the use of institutional controls.

REFERENCES Illinois Administrative Code (IAC), 2004. Title 35: Environmental Protection, Subtitle G: Waste

Disposal, Chapter I: Pollution Control Board, Subchapter f: Risk Based Cleanup Objectives, Part 740, Site Remediation Program.

IAC, 2013. Title 35: Environmental Protection, Subtitle G: Waste Disposal, Chapter I: Pollution Control

Board, Subchapter f: Risk Based Cleanup Objectives, Part 742, Tiered Approach to Corrective Action Objectives.

Illinois Environmental Protection Agency (Illinois EPA), 2015. Spreadsheet entitled “Toxicity Values for

Tier 2 and Tier 3 Applications,” http://www.epa.state.il.us/land/taco/toxicity-values.xls, accessed December 2015.

Johnson, P.C. and Ettinger, R.A., 1991. Heuristic model for predicting the intrusion rate of contaminant

vapors in buildings. Environmental Science and Technology vol. 25, pages 1445-1452. Little, J.C.; Daisey, J.M.; and Nazaroff, W.W., 1992. Transport of subsurface contaminants into

buildings: an exposure pathway for volatile organics. Environmental Science and Technology vol. 26, pages 2058-2066.

USEPA, 2016. Risk Assessment » Regional Screening Levels (RSLs) - Generic Tables (May 2016),

Internet Address: https://www.epa.gov/risk/regional-screening-levels-rsls-generic-tables-may-2016 Accessed July 2016. Files Accessed: (1) Summary Table, Excel format, (2) Chemical Specific Parameters, Excel format, and (3) User’s Guide, HTML format.

* * * * *

https://www.epa.gov/risk

Bloomington MGP Site – 1319/BHA Properties Page 1 of 2 ROR/RAP Amendment

Table A-1Summary of Calculated Residential Remediation Objectives

Tier 3 Indoor Inhalation Exposure Route

Tier 3 Groundwater ROsResidential

Compound/Analyte (mg/L)Volatile Organic Compounds (VOCs)

Acetone 21,000Benzene 0.10Bromodichloromethane 0.032Bromoform 1.3Bromomethane 1.22-Butanone 3,600Carbon disulfide 61Carbon tetrachloride 0.063Chlorobenzene 23Chlorodibromomethane 2,700Chloroform 0.0401,1-Dichloroethane 5,0001,2-Dichloroethane 0.0451,1-Dichloroethene 24cis-1,2-Dichloroethene 6,400trans-1,2-Dichloroethene 4,5001,2-Dichloropropane 0.111,3-Dichloropropene (cis + trans) 0.12Ethylbenzene 0.36Methyl tertiary-butyl ether 2,000Methylene chloride 88Styrene 310Tetrachloroethene 2.4Toluene 5301,1,1-Trichloroethane 1,1101,1,2-Trichloroethane 0.12Trichloroethene 0.17Vinyl chloride 0.047Xylenes, Total 30Notes:

1) bgs - below ground surface; mg/m3 - milligrams per cubic meter; mg/L - milligrams per liter2) ROs shown in italics are based on the solubility limit of the chemical because no inhalation toxicity criteria were available, as discussed in footnotes on Table A-3.


Table A-1 (Continued)Summary of Calculated Residential Remediation Objectives


Tier 3 Groundwater ROsResidential

Compound/Analyte (mg/L)Semivolatile Organic Compounds (SVOCs)

Bis(2-chloroethyl)ether 0.0112-Chlorophenol 11,0001,2-Dichlorobenzene 1201,4-Dichlorobenzene 0.13Hexachlorobenzene 0.0040Hexachlorocyclopentadiene 0.083Hexachloroethane 0.13Isophorone 6,3002-Methylnaphthalene 252-Methylphenol 4,000Nitrobenzene 0.071n-Nitrosodi-n-propylamine 0.0055Phenol 1,900Naphthalene 0.0501,2,4-Trichlorobenzene 1.4

Polychlorinated Biphenyls (PCBs) (mg/kg)Aroclor 1232 0.0031

HeptachlorHeptachlor 0.0019

MercuryMercury 0.060Notes:

1) bgs - below ground surface; mg/m3 - milligrams per cubic meter; mg/L - milligrams per liter2) ROs shown in italics are based on the solubility limit of the chemical because no inhalation toxicity criteria were available, as discussed in footnotes on Table A-3.


Table A-2Input Values for Residential CalculationsTier 3 Indoor Inhalation Exposure Route

Equation/Reference Input Value

Building-Related Parameters

ABSurface area of enclosed space

at or below grade cm2

(same as TACO Equation J&E12a)1.000 x 106

ER Air exchange rate exchangesper hour TACO Appendix C, Table M 0.53

HB Height of building cm TACO Appendix C, Table M 244

LB Length of building cm TACO Appendix C, Table M 1,000

LFDistance from ground surface to

bottom of floor cm TACO Appendix C, Table M 10*

Qbldg Building ventilation rate cm3/s

(same as TACO Equation J&E13)

3.59 x 104

WB Width of building cm TACO Appendix C, Table M 1,000Note:1) * - Although the Tier 3 model assumes no slab is present, setting LF = 10 cm is conservative (shortens the diffusion path length) and results in the appropriate value for LT to maintain consistency with Tier 1 for non-building-related parameters (see page 2 of this table).

Residential Tier 3 Input ValuesUnitsParameterSymbol

( )BBB WLA ×=


Table A-2 (Continued)Input Values for Residential CalculationsTier 3 Indoor Inhalation Exposure Route


Exposure ParametersATc Averaging time for carcinogens year TACO Appendix C, Table M 70

ATncAveraging time for

noncarcinogens year TACO Appendix C, Table M 30

ED Exposure duration year TACO Appendix C, Table M 30

EF Exposure frequency day/year TACO Appendix C, Table M 350

RfC Reference concentration µg/m3 USEPA RSL Tables(1) Chemical Specific

ROindoor aircarc Indoor Air Target Concentration

for carcinogenic chemicals mg/m3


Calculated value

ROindoor airnc Indoor Air Target Concentration

for non-carcinogenic chemicals mg/m3


Calculated value

ROgw-calcGroundwater

remediation objective mg/L

(derived from TACO Equations J&E4 and J&E6)

Calculated value

THQ Target hazard quotient unitless TACO Appendix C, Table M 1

TR Target risk unitless TACO Appendix C, Table M 1 x 10-6

URF Unit risk factor (µg/m3)-1 USEPA RSL Tables(1) Chemical SpecificNote:(1) "USEPA RSL Tables" refers to Regional Screening Level (RSL) Chemical-specific Parameters Supporting Table May 2016 and Regional Screening Level Summary Table May 2016 published by USEPA, https://www.epa.gov/risk/regional-screening-levels-rsls-generic-tables-may-2016

Symbol Parameter UnitsResidential Tier 3 Input Values




Attenuation and Partitioning ParametersDi Diffusivity in air cm2/s USEPA RSL Tables(1) Chemical Specific

Dsoileff Effective diffusion coefficient for

the soil layer cm2/s


Calculated Value

Dcappeff Effective diffusion coefficient for

the capillary fringe cm2/s


Calculated Value

DsourceDistance from ground surface to

top of contamination cm Site-specific value 80.8

DTeff Total overall effective diffusion

coefficient cm2/s

(same as TACO Equation J&E9a)

Calculated Value

Dw Diffusivity in water cm2/s USEPA RSL Tables(1) Chemical Specific

H'TSDimensionless Henry's law

constant at 13°C unitless TACO Appendix C, Table E Chemical Specific

Note:(1) "USEPA RSL Tables" refers to Regional Screening Level (RSL) Chemical-specific Parameters Supporting Table May 2016 and Regional Screening Level Summary Table May 2016 published by USEPA, https://www.epa.gov/risk/regional-screening-levels-rsls-generic-tables-may-2016

Residential Tier 3 Input ValuesSymbol Parameter Units

+

= 2

,

33.3,

'2,

33.3,

iT

iw

TS

w

iT

iai

effi H

DDD

θθ

θθ

+

= 2

,

33.3,

'2,

33.3,

iT

iw

TS

w

iT

iai

effi H

DDD

θθ

θθ

effii

n

i

TeffT

DL

LD/

1=Σ

=




Attenuation and Partitioning Parameters (Continued)

Lcapp Thickness of capillary fringe cm TACO Appendix C, Table M 37.5

Lsoil Thickness of vadose zone soil cmtherefore

(based on TACO Equation J&E9b: )

33.3

LTDistance from bottom of floor to

top of contamination cm


70.8

n

Total number of layers of different types of soil vapors

migrate through from source to building

unitless TACO Appendix C, Table M 2(vadose zone and capillary fringe)

S Solubility in water mg/L USEPA RSL Tables(1) Chemical Specific

T Temperature K TACO Appendix C, Table M 286

α Attenuation factor unitlessLittle, Daisey, and Nazaroff (1992): equation 5, steady state form

Calculated Value

θa,soil Air-filled soil porosity cm3/cm3 TACO Appendix C, Table M 0.28

θa,cappAir-filled porosity of

capillary fringe cm3/cm3 TACO Appendix C, Table M(Capillary Fringe = 0.1 x θT,i)

0.043

θT,i Total porosity of soil layer i cm3/cm3 TACO Appendix C, Table M 0.43

θw,soil Water-filled soil porosity cm3/cm3 TACO Appendix C, Table M 0.15

θw,cappWater-filled porosity of

capillary fringe cm3/cm3 TACO Appendix C, Table M(Capillary Fringe = 0.9 x θT,i)

0.387

Note:(1) "USEPA RSL Tables" refers to Regional Screening Level (RSL) Chemical-specific Parameters Supporting Table May 2016 and Regional Screening Level Summary Table May 2016 published by USEPA, https://www.epa.gov/risk/regional-screening-levels-rsls-generic-tables-may-2016

UnitsResidential Tier 3 Input Values

Symbol Parameter

Ti

n

iLL =Σ

=1

FsourceT LDL −=

𝐿𝐿𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 + 𝐿𝐿𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 = 𝐿𝐿𝑇𝑇 𝐿𝐿𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 = 𝐿𝐿𝑇𝑇 − 𝐿𝐿𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐

α =𝐴𝐴𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏 × 𝐷𝐷𝑇𝑇

𝑒𝑒𝑒𝑒𝑒𝑒

𝑄𝑄𝑏𝑏𝑏𝑏𝑏𝑏𝑏𝑏 × 𝐿𝐿𝑇𝑇


Table A-3Calculation of Residential Groundwater Remediation Objectives


Little, Daisey, & Nazaroff (1992) Calculation of Calculated Solubility SelectedChemical-Specific Parameters Model Calculations Indoor Air Target Concentrations Tier 3 RO Limit Tier 3 RO

Compound/AnalyteDi

(cm2/sec)Dw

(cm2/sec)H'TS

(unitless)URF

(μg/m3)RfC

(mg/m3)Dsoil

eff

(cm2/sec)Dcapp

eff

(cm2/sec)DT

eff

(cm2/sec)α

(unitless)ROindoor air

carc

(mg/m3)ROindoor air

nc

(mg/m3)ROindoor air

(mg/m3)ROgw-calc

(mg/L)S

(mg/L)ROgroundwater

(mg/L)Volatile Organic Compounds (VOCs)

Acetone 1.1E-01 1.2E-05 9.73E-04 NA 3.1E+01 8.4E-03 2.7E-03 4.0E-03 1.6E-03 NC 3.2E+01 3.2E+01 21,000 1.0E+06 21,000Benzene 9.0E-02 1.0E-05 1.34E-01 7.8E-06 3.0E-02 7.0E-03 3.1E-05 5.9E-05 2.3E-05 3.1E-04 3.1E-02 3.1E-04 0.10 1.8E+03 0.10Bromodichloromethane 5.6E-02 1.1E-05 3.71E-02 3.7E-05 NA 4.4E-03 7.5E-05 1.4E-04 5.5E-05 6.6E-05 NC 6.6E-05 0.032 3.0E+03 0.032Bromoform 3.6E-02 1.0E-05 1.06E-02 1.1E-06 NA 2.8E-03 2.3E-04 4.1E-04 1.6E-04 2.2E-03 NC 2.2E-03 1.3 3.1E+03 1.3Bromomethane (Methyl bromide) 1.0E-01 1.4E-05 1.79E-01 NA 5.0E-03 7.8E-03 3.3E-05 6.1E-05 2.4E-05 NC 5.2E-03 5.2E-03 1.2 1.5E+04 1.22-Butanone 9.1E-02 1.0E-05 1.32E-03 NA 5.0E+00 7.2E-03 1.8E-03 2.8E-03 1.1E-03 NC 5.2E+00 5.2E+00 3,600 2.2E+05 3,600Carbon disulfide 1.1E-01 1.3E-05 8.06E-01 NA 7.0E-01 8.3E-03 2.0E-05 3.7E-05 1.5E-05 NC 7.3E-01 7.3E-01 61 2.2E+03 61Carbon tetrachloride 5.7E-02 9.8E-06 7.48E-01 6.0E-06 1.0E-01 4.5E-03 1.2E-05 2.2E-05 8.7E-06 4.1E-04 1.0E-01 4.1E-04 0.063 7.9E+02 0.063Chlorobenzene 7.2E-02 9.5E-06 7.93E-02 NA 5.0E-02 5.6E-03 3.8E-05 7.2E-05 2.8E-05 NC 5.2E-02 5.2E-02 23 5.0E+02 23Chlorodibromomethane 3.7E-02 1.1E-05 2.07E-02 NA NA 2.9E-03 1.2E-04 2.2E-04 8.8E-05 NC NC NC NC 2.7E+03 2,700Chloroform 7.7E-02 1.1E-05 9.18E-02 2.3E-05 9.8E-02 6.0E-03 3.9E-05 7.3E-05 2.9E-05 1.1E-04 1.0E-01 1.1E-04 0.040 8.0E+03 0.0401,1-Dichloroethane 8.4E-02 1.1E-05 1.42E-01 NA* NA 6.5E-03 3.0E-05 5.6E-05 2.2E-05 NC NC NC NC 5.0E+03 5,0001,2-Dichloroethane 8.6E-02 1.1E-05 2.29E-02 2.6E-05 7.0E-03 6.7E-03 1.2E-04 2.3E-04 9.0E-05 9.4E-05 7.3E-03 9.4E-05 0.045 8.6E+03 0.0451,1-Dichloroethene 8.6E-02 1.1E-05 7.10E-01 NA 2.0E-01 6.7E-03 1.7E-05 3.1E-05 1.2E-05 NC 2.1E-01 2.1E-01 24 2.4E+03 24cis-1,2-Dichloroethene 8.8E-02 1.1E-05 1.00E-01 NA NA 6.9E-03 3.9E-05 7.4E-05 2.9E-05 NC NC NC NC 6.4E+03 6,400trans-1,2-Dichloroethene 8.8E-02 1.1E-05 2.43E-01 NA NA 6.8E-03 2.4E-05 4.5E-05 1.8E-05 NC NC NC NC 4.5E+03 4,5001,2-Dichloropropane 7.3E-02 9.7E-06 6.52E-02 1.0E-05 4.0E-03 5.7E-03 4.5E-05 8.5E-05 3.3E-05 2.4E-04 4.2E-03 2.4E-04 0.11 2.8E+03 0.111,3-Dichloropropene (cis + trans) 7.6E-02 1.0E-05 3.98E-01 4.0E-06 2.0E-02 5.9E-03 1.7E-05 3.3E-05 1.3E-05 6.1E-04 2.1E-02 6.1E-04 0.12 2.8E+03 0.12Ethylbenzene 6.8E-02 8.5E-06 1.64E-01 2.5E-06 1.0E+00 5.3E-03 2.2E-05 4.2E-05 1.6E-05 9.7E-04 1.0E+00 9.7E-04 0.36 1.7E+02 0.36Methyl tertiary-butyl ether 7.5E-02 8.6E-06 1.50E-02 NA* 3.0E+00 5.9E-03 1.4E-04 2.6E-04 1.0E-04 NC 3.1E+00 3.1E+00 2,000 5.1E+04 2,000Methylene chloride 1.0E-01 1.3E-05 5.70E-02 1.0E-08 6.0E-01 7.8E-03 6.5E-05 1.2E-04 4.8E-05 2.4E-01 6.3E-01 2.4E-01 88 1.3E+04 88Styrene 7.1E-02 8.8E-06 5.48E-03 NA 1.0E+00 5.6E-03 3.8E-04 6.7E-04 2.6E-04 NC 1.0E+00 1.0E+00 720 3.1E+02 310Tetrachloroethene 5.0E-02 9.5E-06 4.00E-01 2.6E-07 4.0E-02 3.9E-03 1.3E-05 2.5E-05 9.7E-06 9.4E-03 4.2E-02 9.4E-03 2.4 2.1E+02 2.4Toluene 7.8E-02 9.2E-06 1.49E-01 NA 5.0E+00 6.1E-03 2.6E-05 4.9E-05 1.9E-05 NC 5.2E+00 5.2E+00 1,800 5.3E+02 5301,1,1-Trichloroethane 6.5E-02 9.6E-06 4.21E-01 NA 5.0E+00 5.1E-03 1.5E-05 2.8E-05 1.1E-05 NC 5.2E+00 5.2E+00 1,110 1.3E+03 1,1101,1,2-Trichloroethane 6.7E-02 1.0E-05 1.98E-02 NA* 2.0E-04 5.2E-03 1.3E-04 2.3E-04 9.2E-05 NC 2.1E-04 2.1E-04 0.12 4.6E+03 0.12Trichloroethene 6.9E-02 1.0E-05 2.41E-01 4.1E-06 2.0E-03 5.4E-03 2.0E-05 3.8E-05 1.5E-05 5.9E-04 2.1E-03 5.9E-04 0.17 1.3E+03 0.17Vinyl chloride 1.1E-01 1.2E-05 8.14E-01 4.4E-06 1.0E-01 8.4E-03 2.0E-05 3.7E-05 1.5E-05 5.5E-04 1.0E-01 5.5E-04 0.047 8.8E+03 0.047Xylenes, Total** 6.9E-02 8.5E-06 2.71E-01 NA 1.0E-01 5.3E-03 1.8E-05 3.3E-05 1.3E-05 NC 1.0E-01 1.0E-01 30 1.1E+02 30Notes:1) Chemical-specific parameters are from the USEPA Regional Screening Levels (RSLs) Summary Table, revised May 2016.2) Dimensionless Henry's Law Constants (H'TS) are the values contained in TACO, Appendix C, Table E for a system temperature (TS) of 13°C.3) Chemicals shown are the SRP target compounds and analytes that appear on the TACO indoor inhalation volatile chemicals list (TACO, Appendix A, Table J).4) NA - Toxicity information is not available for this chemical for the inhalation route of exposure.5) NC - Not calculated because toxicity information is not available for the inhalation route of exposure.6) ROindoor air is the lesser of the calculated carcinogenic and non-carcinogenic ROs for indoor air.7) Solubility limits are from the USEPA RSLs Summary Table, revised May 2016.8) carc - carcinogenic9) nc - non-carcinogenic10) Selected Tier 3 RO is the lesser of the calculated Tier 3 RO and the solubility limit. If no toxicity criteria were available for the inhalation route of exposure, the solubility limit was selected as the Tier 3 RO, in the same manner as used in Tier 1 (TACO, Appendix B, Table H, Footnote f). ROs based on the solubility limit are shown in italics.11) * - Although a URF is provided in the USEPA RSLs Summary Table, chemical does not meet the statutory definition of a carcinogen as specified in the Illinois Environmental Protection Act (Chapter 415 of the Illinois Compiled Statutes [415 ILCS 5/58.2]).12) ** - No Dimensionless Henry's Law Constant (H'TS) is provided within TACO for total xylenes at 13°C. The value used for the Dimensionless Henry's Law Constant (H'TS) is the value contained in TACO for total xylenes at 25°C, which results in a more conservative groundwater remediation objective for the indoor inhalation exposure route.


Table A-3 (Continued)Calculation of Residential Groundwater Remediation Objectives


Little, Daisey, & Nazaroff (1992) Calculation of Calculated Solubility SelectedChemical-Specific Parameters Model Calculations Indoor Air Target Concentrations Tier 3 RO Limit Tier 3 RO

Compound/AnalyteDi

(cm2/sec)Dw

(cm2/sec)H'TS

(unitless)URF

(μg/m3)RfC

(mg/m3)Dsoil

eff

(cm2/sec)Dcapp

eff

(cm2/sec)DT

eff

(cm2/sec)α

(unitless)ROindoor air

carc

(mg/m3)ROindoor air

nc

(mg/m3)ROindoor air

(mg/m3)ROgw-calc

(mg/L)S

(mg/L)ROgroundwater

(mg/L)Semivolatile Organic Compounds (SVOCs)

bis(2-chloroethyl)ether 5.7E-02 8.7E-06 2.94E-04 3.3E-04 NA 4.7E-03 6.8E-03 5.6E-03 2.2E-03 7.4E-06 NC 7.4E-06 0.011 1.7E+04 0.0112-Chlorophenol 6.6E-02 9.5E-06 7.28E-03 NA NA 5.2E-03 3.1E-04 5.5E-04 2.2E-04 NC NC NC NC 1.1E+04 11,0001,2-Dichlorobenzene 5.6E-02 8.9E-06 3.56E-02 NA 2.0E-01 4.4E-03 6.6E-05 1.2E-04 4.8E-05 NC 2.1E-01 2.1E-01 120 1.6E+02 1201,4-Dichlorobenzene 5.5E-02 8.7E-06 4.69E-02 1.1E-05 8.0E-01 4.3E-03 5.1E-05 9.5E-05 3.7E-05 2.2E-04 8.3E-01 2.2E-04 0.13 8.1E+01 0.13Hexachlorobenzene 2.9E-02 7.8E-06 1.35E-02 4.6E-04 NA 2.3E-03 1.4E-04 2.5E-04 9.7E-05 5.3E-06 NC 5.3E-06 0.0040 6.2E-03 0.0040Hexachlorocyclopentadiene 2.7E-02 7.2E-06 4.22E-01 NA 2.0E-04 2.1E-03 8.1E-06 1.5E-05 6.0E-06 NC 2.1E-04 2.1E-04 0.083 1.8E+00 0.083Hexachloroethane 3.2E-02 8.9E-06 7.26E-02 1.1E-05 3.0E-02 2.5E-03 3.3E-05 6.1E-05 2.4E-05 2.2E-04 3.1E-02 2.2E-04 0.13 5.0E+01 0.13Isophorone 5.3E-02 7.5E-06 1.12E-04 NA 2.0E+00 4.8E-03 1.5E-02 7.5E-03 3.0E-03 NC 2.1E+00 2.1E+00 6,300 1.2E+04 6,3002-Methylnaphthalene 5.2E-02 7.8E-06 6.95E-03 NA NA 4.1E-03 2.6E-04 4.7E-04 1.9E-04 NC NC NC NC 2.5E+01 252-Methylphenol 7.3E-02 9.3E-06 2.00E-05 NA 6.0E-01 1.0E-02 1.1E-01 2.0E-02 7.7E-03 NC 6.3E-01 6.3E-01 4,000 2.6E+04 4,000Nitrobenzene 6.8E-02 9.4E-06 3.99E-04 4.0E-05 9.0E-03 5.5E-03 5.4E-03 5.5E-03 2.2E-03 6.1E-05 9.4E-03 6.1E-05 0.071 2.1E+03 0.071n-Nitrosodi-n-propylamine 5.6E-02 7.8E-06 5.48E-05 2.0E-03 NA 5.8E-03 3.2E-02 1.0E-02 4.0E-03 1.2E-06 NC 1.2E-06 0.0055 1.3E+04 0.0055Phenol 8.3E-02 1.0E-05 6.67E-06 NA 2.0E-01 2.2E-02 3.5E-01 4.3E-02 1.7E-02 NC 2.1E-01 2.1E-01 1,900 8.3E+04 1,900Naphthalene 6.0E-02 8.4E-06 8.29E-03 3.4E-05 3.0E-03 4.7E-03 2.4E-04 4.3E-04 1.7E-04 7.2E-05 3.1E-03 7.2E-05 0.050 3.1E+01 0.0501,2,4-Trichlorobenzene 4.0E-02 8.4E-06 2.38E-02 NA 2.0E-03 3.1E-03 8.7E-05 1.6E-04 6.3E-05 NC 2.1E-03 2.1E-03 1.4 4.9E+01 1.4

Polychlorinated Biphenyls (PCBs) (mg/kg)Aroclor 1232** 3.3E-02 7.5E-06 3.0E-02 5.7E-04 NA 2.6E-03 6.2E-05 1.2E-04 4.5E-05 4.3E-06 NC 4.3E-06 0.0031 1.5E+00 0.0031

HeptachlorHeptachlor 2.2E-02 5.7E-06 1.73E-02 1.3E-03 NA 1.7E-03 7.9E-05 1.4E-04 5.6E-05 1.9E-06 NC 1.9E-06 0.0019 1.8E-01 0.0019

MercuryMercury 3.1E-02 6.3E-06 1.59E-01 NA 3.0E-04 2.4E-03 1.4E-05 2.6E-05 1.0E-05 NC 3.1E-04 3.1E-04 0.19 6.0E-02 0.060Notes:1) Chemical-specific parameters are from the USEPA Regional Screening Levels (RSLs) Summary Table, revised May 2016.2) Dimensionless Henry's Law Constants (H'TS) are the values contained in TACO, Appendix C, Table E for a system temperature (TS) of 13°C.3) Chemicals shown are the SRP target compounds and analytes that appear on the TACO indoor inhalation volatile chemicals list (TACO, Appendix A, Table J).4) NA - Toxicity information is not available for this chemical for the inhalation route of exposure.5) carc - carcinogenic6) nc - non-carcinogenic7) NC - Not calculated because toxicity information is not available for the inhalation route of exposure.8) ROindoor air is the lesser of the calculated carcinogenic and non-carcinogenic ROs for indoor air.9) Solubility limits are from the USEPA RSLs Summary Table, revised May 2016.10) Selected Tier 3 RO is the lesser of the calculated Tier 3 RO and the solubility limit. If no toxicity criteria were available for the inhalation route of exposure, the solubility limit was selected as the Tier 3 RO, in the same manner as used in Tier 1 (TACO, Appendix B, Table H, Footnote f). ROs based on the solubility limit are shown in italics.11) ** - No Dimensionless Henry's Law Constants (H'TS) are provided within TACO for Aroclor 1232. The value used for the Dimensionless Henry's Law Constant (H'TS) is the value contained in the RSLs Summary Table for Aroclor 1232 at 25°C.

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