Groundwater Vulnerability Analysis Assessment Report: Guidance Module 3 RFP Teleconference

1
Groundwater Vulnerability AnalysisAssessment
Report Guidance Module 3RFP Teleconference

• Presentation by
• Rick Vantfoort, Ministry of the Environment
• November 6, 2006

2
Eligible Technical Studies

• Draft Guidance Module 3 Groundwater
  Vulnerability Analysis
• Draft Guidance Module 4 Surface Water
  Vulnerability Analysis
• Draft Guidance Module 5 Issues Evaluation and
  Threats Inventory
• Draft Guidance Module 6 Water Quality Risk
  Assessment

3
Basic Steps

• Basic approach using existing information
• Identify vulnerable areas (WHPAs)
• Map relative intrinsic vulnerability within each
  area (High/Med/Low)
• Establish vulnerability scoring (numeric 2-10)
• Adjust vulnerability (if necessary) to account
  for constructed pathways
• Determine / assign Tier 1 and/or 2 vulnerability
  scores for SQRA
• Assign uncertainty rating (High/Low)
• Provide above results in map form
• Provide input on a continuous improvement plan
• Where prominent data gaps affect the
  hydrogeologic interpretation, additional study or
  use of advanced models may be necessary

4
Models and Methods for WHPA Mapping

• 3D numerical models most commonly used approach
  with the current level of available hydrogeologic
  data
• Simpler (non-numerical) approaches are likely
  appropriate where data and/or risks are limited
  (using existing data)
• Advanced hydrogeological studies may be
  appropriate for complex hydrogeological settings
  (e.g., karst terrain). Additional study must be
  warranted by data gaps and a defined benefit to
  improved model and source protection
• WHPA zones based on Time-of-Travel (TOT) only
  (e.g., 2, 5 and 25 yr)

5
Models and Methods for Vulnerability Assessment

• Basic Hydrogeological Assessment
• Aquifer Vulnerability Index (AVI) / Intrinsic
  Susceptibility Index (ISI) or other index
  approaches
• Surface to Aquifer Advective Time (SAAT)
• Advanced Hydrogeological Assessment
• Special Considerations
• Intrinsic Vulnerability (Chemical Independent)
• Identification of Target Aquifers
• Incorporation of High-Quality Data
• Validation with Observed Water Quality (not
  monitoring)
• Local Scale Improvements

6
Intrinsic Vulnerability Scoring in WHPA
Zone A 100 m
Zone D 25 yr TOT
10
M
M
L
L
8
H
H
H
M
M
6
4
DNAPL Scoring
Pathogen Scoring
2
10 yr TOT
Zone B 2 yr TOT
Zone C 5 yr TOT
7
Constructed Preferential Pathway SQRA Adjustment
(Examples)
Zone A 100 m
Zone D 25 yr TOT
High Density of Improperly Abandoned Boreholes
10
M
M
Quarry
L
L
8
H
H
H
M
M
6
4
2
10 yr TOT
Zone B 2 yr TOT
Zone C 5 yr TOT
8
Uncertainty / Level of Confidence Assessment

• Uncertainty rating assigned to each sensitivity
  area (high/low) for input into Water Quality Risk
  Assessment
• Need to assess uncertainty in both the footprint
  of the vulnerable area and in the vulnerability
  rating
• Considerations include
• input data completeness and reliability
• Model selection, correlation and validity
• Water quality data, if available, may validate
  this analysis
• Will assist in identifying additional data
  analysis or needs in future planning cycles

9
Summary

• Establish vulnerable areas for municipal supply
  wells (WHPAs) based upon available data and
  appropriate methodology
• Assess vulnerability scoring for sensitivity
  areas
• Assess preferential pathways and, if necessary,
  review relative vulnerability
• Assess certainty and determine continuous
  improvement plan

10
T h a n k Y o u !