Current through Register Vol. 48, No. 38, September 20, 2024
a)
Physical and Chemical Properties of Contaminants
Tier 2 evaluations require information on the physical and
chemical properties of the contaminants of concern. The physical and chemical
properties used in a Tier 2 evaluation are contained in Appendix C, Table E. If
the site has contaminants not included in this table, a person may request the
Agency to provide the applicable physical and chemical input values or may
propose input values under Subpart I. If a person proposes to apply values
other than those in Appendix C, Table E, or those provided by the Agency, the
evaluation shall be considered under Tier 3.
b) Soil and Groundwater Parameters
1) A Tier 2 evaluation requires examination
of soil and groundwater parameters. The parameters that may be varied, and the
conditions under which these parameters are determined as part of Tier 2, are
summarized in Appendix C, Tables B, D, and M. If a person proposes to vary
site-specific parameters outside of the framework of these tables, the
evaluation shall be considered under Tier 3.
2) To determine site-specific physical soil
parameters, a minimum of one boring per 0.5 acre of contamination shall be
collected. This boring must be deep enough to allow the collection of the
required field measurements. The site-specific physical soil parameters must be
determined from the portion of the boring representing the stratigraphic units
being evaluated. For example, if evaluating the soil component of the
groundwater ingestion exposure route, two samples from the boring will be
required:
A) A sample of the predominant soil
type for the vadose zone; and
B) A
sample of the predominant soil type for the saturated zone.
3) A site-specific SSL dilution
factor (used in developing soil remediation objectives based upon the
protection of groundwater) may be determined by substituting site information
in Equation S22 in Appendix C, Table A. To make this demonstration, a minimum
of three monitoring wells shall be used to determine the hydraulic gradient. As
an alternative, the default dilution factor value listed in Appendix C, Table B
may be used. If monitoring wells are used to determine the hydraulic gradient,
the soil taken from the borings shall be visually inspected to ensure there are
no significant differences in the stratigraphy. If there are similar soil types
in the field, one boring shall be used to determine the site-specific physical
soil parameters. If there are significant differences, all of the borings shall
be evaluated before determining the site-specific physical soil parameters for
the site.
4) Not all of the
parameters identified in Appendix C, Tables B, D, and M need to be determined
on a site-specific basis. A person may choose to collect partial site-specific
information and use default values as listed in Appendix C, Tables B, D, and M
for the rest of the parameters.
