Conceptual Site Models much more than a pretty picture

1. Conceptual Site Models much more than a pretty picture

2. Conceptual Site Models… Much more than a pretty picture Tuesday 24 SeptemberALGA Industry Forum, DLA Piper

3. Traditional Conceptual Site Model (CSM) • The single Cross Section, only used for • the risk assessment phase Box Ticked • Source: USEPA Region 4: Conceptual Site Model (CSM)

4. So – What More Can You Do with a CSM? NEPM 2013, Schedule B2: Site Characterisation The development of a CSM is an essential part of all site assessments and provides the framework for identifying how site is contaminated and how potential receptors may be exposed. Definition: A conceptual site model (CSM) is a representation of site-related information regarding contamination sources, receptors and exposure pathways between those sources and receptors.

5. Content of Presentation Elements of CSMs – Sources, Pathways and Receptors Five ways to use CSMs as site representations, they can provide: A logical approach to the design of Sampling and Analysis Plans (SAPs) Relevant investigation criteria for Tier 1 Assessments A dynamic/iterative process, using results to revise and update SAPs A frame work for Tier 1 through to Tier 3 Risk Assessment A user friendly risk communicative tool for community consultation

6. Elements of CSMs – Sources, Pathways and Receptors • Essential elements of CSMs • The essential elements of an initial CSM are: • SOURCES PATHWAYS RECEPTORS • known and potential sources of contamination and contaminants of concern • potential and complete exposure pathways • human and ecological receptors • All of these issues should be identified in the initial CSM.

7. Sources • Known and potential, including: • historical and current land uses • the mechanism(s) of loss • e.g. ‘top down’ surface spill vs sub-surface release • Resources (unknown): • Aerial photographs • Certificate of title search • Interviews and site walkovers • Site plans and databases (DMP, DER CS etc) • Local historical data • Resources (known): • Incident Reports • Previous Investigations

8. Aerial Photographs

9. N • Site Plans and Databases (DMP, DER CS etc) LEGEND Site Boundary Regional Groundwater Flow Direction DEC Contaminated Site Location 2006 Geotech Test Pits and Soil Bores (Classification) Lot 512 (Contaminated – Remediation Required) Kwinana Marshalling Yards Hydrocarbon contamination in soil and groundwater (including phase separated hydrocarbons) towards the southern portion of the Site. Lot 511 (Contaminated – Remediation Required) Kwinana Marshalling Yards Hydrocarbon contamination in soil and groundwater (including phase separated hydrocarbons) towards the southern portion of the Site.

10. Pathways • Naturally derived, including: • topography/drainage • geology • hydrogeology (depth to and direction of groundwater flow) • Anthropogenic, including: • subsurface utility trench and barriers • irrigation or potable extraction bores Extents of Site Audit 2006 Geotech Test Pits and Soil Bores ? ?

11. Topography/drainage Hydrogeology (depth to and direction of groundwater flow) Extents of Site Audit 2006 Geotech Test Pits and Soil Bores ? ?

12. Irrigation or potable extraction bores Extents of Site Audit 2006 Geotech Test Pits and Soil Bores ? ?

13. Receptors • Human, including: • on site workers • onsite occupants • down-hydraulic gradient offsite occupants • Ecological, including: • aquatic ecosystems • terrestrial ecosystems Extents of Site Audit 2006 Geotech Test Pits and Soil Bores ? ?

14. Future Human Landuse

15. Aquatic ecosystems

16. CSM Use #1: A logical and structured approach to design Sampling and Analysis Plans (SAPs) Identifying Datagaps • Multiple presentations available: • Tables • 2D - Plans • 3D/Sections

17. CSM Use #1: Example – Tables – Potential Areas of Environmental Concern

18. CSM Use #1: Example – 3D/Sections

19. CSM Use #1: Example – 2D Plans Source: Bureau Veritas

20. Summary CSM Use #1: • Data gap identification and uncertainty assessment are key activities in developing and refining a CSM and the SAP • Multiple ways to represent this using the CSM process

21. CSM Use #2: Choosing the relevant investigation levels for site • (DEC 2010) Assessment Levels for Soil, Sediment and Water • The selection of appropriate assessment levels is based on the identified beneficial use e.g: • support for aquatic ecosystems • public drinking water supply • domestic non-potable water use or public/agricultural irrigation. • Depending on the conceptual site model, assessment against more than one investigation level may be required.

22. CSM Use #2: Example Source: DEC DATA GAP ANALYSIS AND CONCEPTUAL SITE MODEL

23. CSM Use #3: A dynamic/iterative process, using results and data to revise and update SAPs • The development of a CSM is a dynamic process • Information and data from each stage used to refine the CSM • Datagaps identified • SAP reviewed and updated • The CSM should be continually challenged and updated throughout the assessment process.

24. CSM Use #3: Example – Unexpected Ammonia Result Source: DP

25. CSM Use #3: Example – Unexpected Ammonia Result

26. CSM Use #3: Example – Unexpected Ammonia Result

27. CSM Use #4: A frame work for Tier 1 through to Tier 3 Risk Assessment • A CSM should identify complete and potential pathways between the known or potential source(s) and the receptor(s). • Where the pathway between a source and a receptor is incomplete, the exposure to chemical substances via that pathway cannot occur. • Best way to demonstrate complete and incomplete pathways is the ASTM style flow chart.

28. CSM Use #4: Example - Flowchart    

29. CSM Use #5: Risk Communication Tool • Everyone can follow a flow chart • Provides transparently clear pathways which are immediately obvious to the layman (public) • It is the most helpful piece of presentation material for use in public meetings

30. CSM Use #5: Example – DERs Esperance Health Risk Assessment Source: DEC DATA GAP ANALYSIS AND CONCEPTUAL SITE MODEL

31. Summary - Benefits of Using Multiple CSM Representations X • Defines the study early in the process • Helps focus data needs and develop SAPs • Allows updating of the SAP throughout the project • Clarifies the risk assessment and management goals • Provides a user friendly communication tool

32. ? Questions and Comments

33. Conceptual Site Models – not just a pretty picture, an Auditor’s perspective John Throssell | Principal Environmental Hydrogeologist Image placeholder Image placeholder Image placeholder

34. Thinking conceptually Conceptualisation of your site starts when you read the RFP and commence writing the proposal. Your are still conceptualising when you issue the final report and the final invoice to the client. The challenge in reporting on contaminated land investigations is to; move on from the metronomic regurgitation of data (which quickly looses the readers attention), to being able to describe the site within its surroundings and the relationships between sources, pathways and receptors of contaminants (pretty pictures help).

35. What does the guidance tell us? NEPM Schedule B2 – Site Characterisation Introduction Stages of investigation Preliminary investigations Conceptual site models Systematic planning for collection of environmental data Sampling design Soil assessment…etc CRC CARE Technical Report No. 13 Field Assessment of vapours Introduction Conceptual site model and vapour behavior Guidance documents Framework for vapour assessment Design issues for field assessment of vapours…etc

36. What does the guidance tell us? CRC CARE Technical Report No. 13 • Introduction • Overview of petroleum hydrocarbons • Site characterisation strategies • 3.2 Developing an SCM for hydrocarbon sites 4. Investigation methods 5. Data presentation and reporting…etc There is a consistent message here…start conceptualising your site early! Comment… A preliminary SCM should be an output of the PSI, an input to the development of DQOs and the investigation design, and a revised SCM should be presented as an output of each stage of the DSI.

37. CSMs and the data cycle forms the basis for DQO process

38. Keeping the Auditor happy CSMs should provide a foundation for the development of data quality objectives and sampling design. • They should consider all potential exposure scenarios • They are dynamic and should be refined throughout the assessment process. • Level of detail in the CSM will be relative to the • phase of investigation being undertaken at the site • scale and complexity of the impacts present at the site of interest. • Draws data together in a meaningful way by linking: • Geology, Hydrogeology and Hydrogeochemistry of the environment with • Sources, pathways (inc. fate & transport) and receptors of the contamination • It is a product of the assessment and understanding of numerous detailed, interrelated and corroborated data sets, that must be undertaken before distilling them into an ‘easy-to-follow’ model of the way the site works.

39. CSM incorporating DQO’s

40. Simple Flow Chart Type CSM

41. Groundwater Transport Type CSM

42. Cross-section Type

43. Detailed Model

44. Conceptual Site Models and Audits • Helps the auditor see the level of understanding the consultant has of the site and the related contamination issues. • Good SCMs present both the macro and the micro attributes of the site.

45. Conceptual Site Models and Audits • Understanding of source/pathway/receptor relationships at the macro scale is acceptable at the PSI stage. • Iterative development of the CSM on the micro scale occurrs during the DSI process. • Modelling, risk assessment etc must be based on clear understanding at the micro scale (refer CRC CARE Technical Report no.13 for excellent examples relating to vapour intrusion) • CSMs are fundamental in distilling the input of multidisciplinary teams involved in characterisation and remediation of contaminated sites. • Must be able to communication the concepts of land contamination to non-technical stakeholders.

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47. Conceptual Site Models much more than a pretty picture