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 ProcessLevel 2 – The SRA-2 Process

Other Standards and Guidance Initiatives

Overview of the SAB

Paul West

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 officesabcs@uvic.ca

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

Risk Assessment in Contaminated Sites

Management

Marc Cameron

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.”

Contaminated Sites Process

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.

Risk Assessment Process

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.

Risk Assessment and Contaminated Sites

High Risk Screening and Classification Process

Dennis Konasewich

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

Screening Risk Assessment

SRA-1 Status Report

Will Gaherty

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)

How it works?

Barriers Distance to receptors

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

Screening Risk Assessment

SRA-2 Status Report

Jean Cho

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

Other Standards and Guidance Initiatives

Jim Malick

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

Other Projects in Progress Cont.

Recommendations for revision of Soil Groundwater Model (Based on Completed Review)

Further recommendations on NSTS (Non-Scheduled Toxic Substances)