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Contaminated Sites Workshop – Science Advisory Board Projects. September 28, 2004. Agenda. Overview of the SAB Risk Assessment in Contaminated Sites Management High Risk Screening and Classification Process Screening Risk Assessment Level 1 – The SRA-1 Process Level 2 – The SRA-2 Process - PowerPoint PPT Presentation
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Agenda Overview of the SAB Risk Assessment in Contaminated Sites
Management High Risk Screening and Classification
Process Screening Risk Assessment
Level 1 – The SRA-1 ProcessLevel 2 – The SRA-2 Process
Other Standards and Guidance Initiatives
Background
A unique model in British Columbia Independent Board of Directors Registered under the Societies ActAn agency at the University of VictoriaFunding from the Ministry of Water Land and
Air ProtectionA Recommendation of the Minister’s Panel on
Contaminated Sites
First AGMOctober 14, 2004
Morris J. Wosk Centre for Dialogue580 West Hastings Street
Vancouver, BC
11:30 – 2:00pm
Contact: Sara Alvarez in the SAB [email protected]
Additional information on Risk Guidance
Membership Criteria
Advanced degrees in pertinent science and engineering disciplines
Number of years experience Professional credentials Leadership in the discipline Field or lab experience Evidence of ability to produce peer
reviewed or other professional literature
More Information
The SAB’s website can be found at:
www.sabcs.chem.uvic.ca Terms of Reference Constitution and Bylaws Nomination Form Contact Information News and Recent Documents
Contaminated Sited and Risk Assessment Site determined to be contaminted Site with chemicals present at concentration
greater than BC Numerical Standards or Criteria. Section 16 of the Contaminated sites regulation
states “The numerical standards, or the risk based standards prescribed in section 18 or 18.1, may be used in relation to the remediation of a contaminated site.”
When is risk assessment is employed? At some sites it is not possible or practical
to remove substances due to technological, physical or financial constraints.
When a site owner selects the risk-based approach, it allows the risks associated with leaving substances in place to be estimated.
When is risk assessment is employed? The mere presence of a substance or
contaminant at a site does not necessarily constitute a risk. In order for a risk to exist, the following three basic conditions must be met: substances must be present; these substances must be able to cause toxic or other
adverse biological effects — that is substances must be hazardous; and
pathways by which humans, animals or plants (receptors) may be exposed to substances must exist.
Risk Assessment
Risk assessment uses mathematical models to predict the dose (amount of chemical), which is the amount of a substance received by a receptor by any specific exposure pathway.
Provided that the safe dose is not exceeded, there is little risk that exposure to the substance will adversely affect the health of receptors.
Risk Assessment
Risk assessment is a tiered process with each tier generaly requiring the collection of additional and more detailed site specific information.
Tier 1 Screening Level SRA1 SRA2
Tier 2 Baseline –deterministic Tier 3 Detailed –focused on specific issues and
often probabilistic
Risk Assessment in British Columbia SAB to develop and oversee the development of
Screening Level Risk Assessment Guidance and Detail Risk Assessment Guidance.
It is the intent of the SAB to have these guidance documents build on one another so as to reduce reduce, redundancy.
The screening level risk assessment looks at assessing pathways of exposure to receptors of interest.
Background – Panel report
Focus regulatory resources on high-risk sites
Establish stand-alone and independent system of licensed environmental professionals- allow them to oversee non-high risk sites
Establish SAB to develop screening level risk-assessment methodology
Ministry’s proposed process
Investigation and remediation of all but high risk contaminated sites under licensed professionals.
Ministry will guide and direct remediation process on high risk contaminated sites and sites undergoing risk-based remediation
Ministry will also review and develop new standards and protocols.
Compliance acceptance
Retain existing approach of using numeric standards to classify a site
Added two protocols: high risk identification, and pathway/receptor screening assessment
Ministry requirements for identification of
high risk contaminated sites Level 1: Initial high risk procedure largely
consisting of prohibiting conditions Level 2: Development of high spot numbers
representing concentrations capable of causing significant harm and in combination with other prescribed conditions
Level 3: Consideration of a scoring system for classification
Definition of a “high risk” contaminated site-WLAP references
WMA 27.1(8) reference to “imminent and significant threat or risk to human health, given current and anticipated human exposure, or the environment“
Sites that require immediate regulatory attention
High risk identification process must: Be representative of good science Be pragmatic Enable a reasonable selection process
Assure high risk sites are appropriately identified
Assure that the number of “non-high” risk sites selected as “high risk” is minimal.
Time-frame for SAB
Report status to the Ministry September 30
Undertake additional work and complete draft procedure by November 15
Present SAB reviewed draft to the Ministry on November 30
Approach
Discussion with Ministry Discussions with consulting community Discussions with federal agencies Literature Review Consideration of approaches already developed Workshop Board discussions
Context of SRA-1
SRA-1 - simple rules - all LEPs SRA-2 - simple models - some LEPs DRA-1 - simplified risk assessment -
MWLAP DRA-2 - unconstrained risk assessment -
MWLAP
What is SRA-1?
Avoid “full blown” risk assessment at lowest risk sites that exceed numerical standards
Few if any similar approaches elsewhere, so built from scratch
What is SRA-1?
12-17 “yes/no” questions total, in three modules
Human and ecological risk Minimal professional judgement
(audit/liability)
Comments on Draft
Comments from roughly 8 sources General feeling that SRA1 highly
restrictive Comments helpful, but SRA2 had more
impact
Revisions
Framework basically unchanged from original draft
Clarification of a number of issues Questions quite different
Where Next?
Limited circulation now Submit to MWLAP in next week or so Field trials will tell a lot Science moving fast in some areas Experience with SRA2 will help, too
Outline
Pathways Evaluated in SRA-2Vapour Intrusion into Occupied BuildingsLeaching of Soil Contaminants to
GroundwaterTransport in Groundwater to Water Supply
WellTransport in Groundwater to Aquatic Receptor
Habitat Viability Issues Also Addressed
Schematic of Pathways
AquaticReceptor
HumanReceptor(vapour)
Contaminant Source
HumanReceptor(watersupply well)
Pathway 2.Soil to groundwater
Pathway 4. Via groundwaterto aquatic receptor
Pathway 3.Via groundwaterto water supply well
Pathway 1.Via soil vapourto human receptor
Pathway 1 – Soil Vapour Intrusion Input from 14 Scientists and Engineers
7 SAB MembersUSEPA, Health Canada, MWLAP, U of A, U
of T6 Consultants3 Reviewers
Pathway 1 – Soil Vapour Intrusion Partitioning Vapour
Attenuation Indoor Air
Concentration HQ (hazard
quotient) orILCR (incremental lifetime cancer risk)
Vapour-PhaseContaminantin Soil Air
Dissolved PhaseContaminantin Soil Water
Sorbed PhaseContaminantin/on Soil Matrix
Pathways 2 to 4 – Soil / GW
Presented in a Single Document Input from 20 Scientists and Engineers
12 SAB Members GSC, UBC, MWLAP, WA state, CPPI 8 Consultants 4 Reviewers
Pathway 2 Based on US EPA Soil Screening Guidance
Pathway 3 – Groundwater to Well
Aquifer Classification Suitability as
resource Potential for
future use Vulnerability
Pathways 3 & 4 – Groundwater Transport Quantify risk
using cross-plots
Sensitivity Analysis
Cleanup Standard
SRA-2 Habitat Assessment
Input from 13 Scientists and Engineers7 SAB MembersUSEPA, MWLAP, Western Washington U.6 Consultants3 Reviewers
SSS Model Review
Part of Protocol 2 Two external reviews
Chris Neville of Papodapulos & AssociatesJean ChoOpinion letter from John Cherry
Completed Projects (Posted)
Initial Review of CCME Canada Wide Standards for Petroleum Hydrocarbons
SRA1 – Initial Draft: Screening Risk Assessment Level 1 Guidance (May 2004)
Report of the EPH/LEPH/HEPH Task Force
Other Projects in Progress
Detailed Risk Assessment 1 (DRA-1) – Standard, deterministic
Detailed Risk Assessment 2 (DRA-2) – Extended, including stochastic methods
Review of Contaminated Soil Standards Task Group (CSST) Standards Derivation Protocol