Affected Property Assessment Requirements under TRRP Page: 2
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Affected Property Assessment Requirements under TRRP
protective concentration level exceedance (PCLE) zones, and discusses
some issues that may be encountered that warrant specific consideration.
Determining the Assessment Level
The term "assessment level" is used in TRRP to denote the concentration
to which the three-dimensional extent of a COC in the environment must
be assessed. The assessment level always includes human health
exposure pathway considerations, and when appropriate, ecological
exposure pathways considerations. An assessment level is typically a
calculated risk-based value that factors in different exposure
considerations for different environmental media (e.g., surface soil,
subsurface soil, groundwater) as well as COC-specific physical and
chemical properties, and toxicity factors. Human health considerations
are based on residential exposure.
Table 1 identifies some site-specific inputs that are necessary to determine
the assessment level. With the exception of source area size
considerations and standard exposure pathways, the different topics are
addressed in other guidance documents. See the documents referenced in
Table 1 for details on those subjects. With regard to more explanation of
their bearing on setting assessment levels, see TCEQ guidance document
Affected Property Assessment Planning (RG-366/TRRP-6).
Table 1. Important Information for Establishing Assessment Levels.
Topic Impact Guidance Document
The assessment must consider the appropriate COCs since
Target COCs assessment levels are COC-specific values that reflect the toxicity TRRP-10
and chemical/physical properties of the COC.
Groundwater Groundwater classification establishes relevant exposure TRRP-8
Classification- pathways.
An assessment level includes ecological screening benchmarks
Applicability of and PCLs when there are ecological exposure concerns.
Ecological Risks- Ecological levels can be lower than the human health-based RG-263 (revised)
assessment levels.
Method Quantitation The MQL or background concentration may substitute for the TRRP-13 (MQL)
Limits/Background2 assessment level when it is a higher value. TRRP-15 (Background)
Source Area Size Assessment levels for certain exposure pathways are dependent This document
on the source area size of the COC.
1. If unknown, assume Class 1 groundwater.
2. Can set assessment levels initially on human health and later define ecological PCLs, but at risk of mobilizing for
additional assessment.
3. Establishing a background concentration is optional, but it may prevent setting assessment levels inappropriately
low for a COC, such as an inorganic COC that is naturally occurring in the environment..Revised May 2010
TCEQ publication RG-366/TRRP-12
2
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Texas Commission on Environmental Quality. Remediation Division. Affected Property Assessment Requirements under TRRP, pamphlet, May 2010; Austin, Texas. (https://texashistory.unt.edu/ark:/67531/metapth624212/m1/2/: accessed July 18, 2024), University of North Texas Libraries, The Portal to Texas History, https://texashistory.unt.edu; crediting UNT Libraries Government Documents Department.