Section 742.935  Indoor Inhalation Exposure Route

a)         Exclusion of Exposure Route

Site information may demonstrate that there is no actual or potential impact of contaminants of concern to receptors from the indoor inhalation exposure route.  In these instances, a demonstration excluding the exposure route shall be submitted to the Agency for review and approval.  A submittal under this Section shall include the following information:

1)         A description of the site, physical site characteristics, existing and planned buildings, and existing and planned man-made pathways; and

2)         A discussion of the possibility of the route becoming active in the future.

b)         Exclusion of Exposure Route Using Building Control Technologies

Any proposals to use building control technologies as a means to prevent or mitigate human exposures under the indoor inhalation exposure route that differ from the requirements of Subpart L shall be submitted to the Agency for review and approval.  A submittal under this Section shall include the following information:

1)         A description of the site and physical site characteristics;

2)         The current extent and modeled migration of contamination;

3)         Geology, including soil types and parameters;

4)         Results and locations of sampling events;

5)         Scaled map of the area, including all buildings and man-made pathways;

6)         A description of building characteristics and methods of construction, including a description of man-made pathways; 

7)         Present and post-remediation uses of the land that are at issue due to the area of contamination, including human receptors at risk;

8)         A description of  any building control technologies currently in place or proposed for installation that can reduce or eliminate the potential for completion of the exposure route, including design and construction specifications;

9)         Information regarding the effectiveness of any building control technologies currently in place or proposed for installation and a schedule for performance testing to show the effectiveness of the control technology.  For buildings not yet constructed, an approved building control technology shall be in place and operational prior to human occupancy;

10)         Identification of documents reviewed and the criteria used in the documents for determining whether building control technologies are effective and how those criteria compare to existing or potential buildings or man-made pathways at the site; and

11)         A description as to how the effectiveness of the building control technologies will be operated and maintained for the life of the buildings and man-made pathways, or until soil gas and groundwater contaminant concentrations have reached remediation objectives that are approved by the Agency.  This includes provisions for potential extended system inoperability due to power failure or other disruption.

c)         Calculations and Modeling Used to Establish Soil Gas Remediation Objectives

The calculations and modeling shall account for contaminant transport through the mechanisms of diffusion and advection.  Proposals to use soil gas data, including sub-slab samples, to establish remediation objectives for the indoor inhalation exposure route that differ from the requirements of Section 742.227 shall be submitted to the Agency for review and approval.  A submittal under this Section shall include the following information:

1)         Scaled map of the area, showing all buildings and man-made pathways (current and planned);

2)         The current extent and modeled migration of contamination;

3)         Geology, including soil types and parameters;

4)         Depth to groundwater (including seasonal variation) and flow direction;

5)         Location of soil gas sampling points;

6)         A discussion of soil gas sampling procedures that, at a minimum, addresses the following:

A)        sampling equipment;

B)        soil gas collection protocol, including field tests and weather conditions; and

C)        laboratory analytical methods.

d)         Calculations and Modeling Used to Establish Soil Remediation Objectives

The calculations and modeling shall account for contaminant transport through the mechanisms of diffusion and advection.  Any proposals to use soil data in lieu of soil gas data to establish remediation objectives for the indoor inhalation exposure route shall be submitted to the Agency for review and approval.  A submittal under this Section shall include the following information:

1)         Scaled map of the area, showing all buildings and man-made pathways (current and planned);

2)         The current extent and modeled migration of contamination;

3)         Geology, including soil types and parameters;

4)         Location of soil sampling points;

5)         A discussion of soil sampling procedures that, at a minimum, addresses the following:

A)        sampling equipment;

B)        soil collection protocol, including field tests and weather conditions; and

C)        laboratory analytical methods;

6)         Mathematical and technical justification for the model proposed; and

7)         Demonstration that the model was correctly applied.

e)         Calculations and Modeling Used to Establish Groundwater Remediation Objectives

The calculations and modeling shall account for contaminant transport through the mechanisms of diffusion and advection.  Proposals to use groundwater data to establish remediation objectives for the indoor inhalation exposure route that differ from the requirements of Sections 742.805 and 742.812 shall be submitted to the Agency for review and approval.  A submittal under this Section shall include the following information:

1)         Scaled map of the area, showing all buildings and man-made pathways (current and planned);

2)         The current extent and modeled migration of contamination;

3)         Geology, including soil types and parameters and the thickness of the capillary fringe;

4)         Depth to groundwater (including seasonal variation) and flow direction;

5)         Results and locations of groundwater sampling events;

6)         Mathematical and technical justification for the model proposed; and

7)         Demonstration that the model was correctly applied.

(Source:  Added at 37 Ill. Reg. 7506, effective May 15, 2013)