CONCEPTUAL SITE MODEL (CSM)

Report
THE CONCEPTUAL SITE MODEL
A Visual Journey Though Data and Time
October 29, 2013
CONCEPTUAL SITE MODEL
WHAT IS A CONCEPTUAL SITE MODEL ?
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CONCEPTUAL SITE MODEL
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A Conceptual Site Model (CSM) describes site features and
surface/subsurface conditions to understand contaminants
and the risk(s) they pose to receptors.
CONCEPTUAL SITE MODEL
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A CSM is included in the Part 213 definition of RBCA which directly
references the ASTM:
Standard guide for development of conceptual site models and
remediation strategies for light nonaqueous-phase liquids released to
the subsurface, designation E 2531-06 E1, which references the
Standard guide for development of conceptual site models for
Contaminated Sites, designation E 1689-95 (Reapproved 2008), which
states (paraphrased):
A CSM is a written or pictorial representation of an
environmental system and the processes that determine
transport of contaminants from sources to receptors.
CONCEPTUAL SITE MODEL
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A CSM describes site conditions by:
- Identifying sources, pathways and receptors for
contamination.
- Identifying critical biological, chemical or physical
processes.
- Identifying the presence (and absence) of contamination.
CONCEPTUAL SITE MODEL
The CSM is an EVOLVING document.
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CONCEPTUAL SITE MODEL
DEVELOPMENT OF A CONCEPTUAL SITE MODEL
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CONCEPTUAL SITE MODEL
1. Scope
2. Summary
3. Sources
4. Pathways and Receptors
5. Narrative and Visual Description
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CONCEPTUAL SITE MODEL
1. Scope of the Conceptual Site Model
- What Needs to be Characterized
- Extent of Area to be Investigated
- Human and/or Ecological Receptors
- Contaminants of Concern (COCs)
- Applicable Remedial Criteria
- Immediate/Long Term Environmental Concerns
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CONCEPTUAL SITE MODEL
2. Summarize Available Information
- Property Description
- Historical Information
- Off-site and Regional Information
- Geologic and Hydrogeological Information
- Other
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CONCEPTUAL SITE MODEL
3. Identify and Characterize Sources
- Operational and Ownership History
- Current and Historic Releases
- Location and Content of Releases
- Extent/Volume/Mass
- Prior Remedial Actions
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CONCEPTUAL SITE MODEL
4. Identify Pathways and Receptors
- Exposure Pathways
• Current
• Potential Future Use
- Human and/or Ecological Receptors
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CONCEPTUAL SITE MODEL
4. Identify Pathways and Receptors
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CONCEPTUAL SITE MODEL
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5. A Narrative and Visual Description
- Puts all the pieces together in a summary fashion for the
site as it is understood at that time.
- The CSM should describe the site, contaminants,
pathways, and receptors. More complex sites should
include a discussion of data gaps or uncertainties.
Note: this is probably the most critical part of a CSM. You need to be
able to provide a clear description of your model and graphics with an
explanation are a great way to do this.
CONCEPTUAL SITE MODEL
LET THE FUN BEGIN…
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CONCEPTUAL SITE MODEL
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CONCEPTUAL SITE MODEL
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CONCEPTUAL SITE MODEL
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CONCEPTUAL SITE MODEL
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The Narrative:
A release of NAPL occurred from a dispenser. That NAPL
migrated into the subsurface and migrated along a clay
layer at 10 feet and then entered an aquifer 30 feet west of
the source. The NAPL then pancaked in a classical fashion
and created a groundwater plume that is migrating to the
NE. That plume included BTEX at levels representative of a
NAPL source and has migrated 260 feet down-gradient.
The source area presents a VI risk but soil vapor data
indicate that the risk is contained and has not reached any
structures. Down-gradient drinking wells are in the path of
migration of the dissolved phase…
CONCEPTUAL SITE MODEL
Contact Information
Joseph DeGrazia, C.P.G.
Senior Geologist
Michigan Department on Environmental Quality
Remediation and Redevelopment Division
Southeast Michigan District Office
(586) 753-3812
[email protected]
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