1. THE CONCEPTUAL SITE MODEL A Visual Journey Though Data and Time October 29, 2013

2. C ONCEPTUAL S ITE M ODEL _ WHAT IS A CONCEPTUAL SITE MODEL ?

3. C ONCEPTUAL S ITE M ODEL _ A Conceptual Site Model (CSM) describes site features and surface/subsurface conditions to understand contaminants and the risk(s) they pose to receptors.

4. C ONCEPTUAL S ITE M ODEL _ 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.

5. C ONCEPTUAL S ITE M ODEL _ 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.

6. C ONCEPTUAL S ITE M ODEL _ The CSM is an EVOLVING document.

7. C ONCEPTUAL S ITE M ODEL _ DEVELOPMENT OF A CONCEPTUAL SITE MODEL

8. C ONCEPTUAL S ITE M ODEL _ 1.Scope 2.Summary 3.Sources 4.Pathways and Receptors 5.Narrative and Visual Description

9. C ONCEPTUAL S ITE M ODEL _ 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

10. C ONCEPTUAL S ITE M ODEL _ 2. Summarize Available Information -Property Description -Historical Information -Off-site and Regional Information -Geologic and Hydrogeological Information -Other

11. C ONCEPTUAL S ITE M ODEL _ 3.Identify and Characterize Sources -Operational and Ownership History -Current and Historic Releases -Location and Content of Releases -Extent/Volume/Mass -Prior Remedial Actions

12. C ONCEPTUAL S ITE M ODEL _ 4. Identify Pathways and Receptors - Exposure Pathways Current Potential Future Use - Human and/or Ecological Receptors

13. C ONCEPTUAL S ITE M ODEL _ 4. Identify Pathways and Receptors

14. C ONCEPTUAL S ITE M ODEL _ 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.

15. C ONCEPTUAL S ITE M ODEL _ LET THE FUN BEGIN…

16. C ONCEPTUAL S ITE M ODEL _

20. 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…

21. C ONCEPTUAL S ITE M ODEL _ 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 degraziaj@michigan.gov