Groundwater Quality Vulnerability Analysis - WHPA delineation & - - PowerPoint PPT Presentation

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Groundwater Quality Vulnerability Analysis - WHPA delineation & - - PowerPoint PPT Presentation

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Groundwater Quality Vulnerability Analysis

  • WHPA delineation & vulnerability

CTC SWP Committee October 20, 2009 Rick Gerber

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1) Technical Rules/Technical Bulletins

  • > November 20, 2008

2) WHPA & Vulnerability Delineation

  • Velocity/travel times

3) Peel Region (TRCA) WHPAs

  • Earthfx Inc (October 17, 2007)
  • AMEC Peer Review (August 21, 2009)

4) Conclusions/Discussion

Overview Overview

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Slide modified from MOE 24-Mar-2009

  • 1. Technical Rules/Bulletins (Nov, 2008)
  • 1. Technical Rules/Bulletins (Nov, 2008)

Groundwater Quality Vulnerability Analysis – WHPA

  • Assess the intrinsic vulnerability according to the natural susceptibility of

aquifers to becoming contaminated 1) Delineate Wellhead Protection Area (WHPA-A,B,C,D; Part V Part V); 2) Determine natural vulnerability of aquifer system to contaminants (H,M,L – Part IV Part IV); 3) Overlay 1 & 2 to determine vulnerability scores (Part VII.3 Part VII.3). Consider anthropogenic transport pathways (Part IV Part IV) Assess uncertainty with plans for continuous improvement (Part I.4 Part I.4)

  • Threats and Issues mapping within WHPA (Vulnerability score of 6) (Part XI

Part XI)

  • Risk Score = Hazard Rating (1-10) x Vulnerability Score (6) (Part XI

Part XI) Vulnerability score <=6 cannot contain a significant threat (Significant > 80; Moderate 60-79; Low 40-59)

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Slide from MOE 24-Mar-2009

6 4 2

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  • 2. WHPA & Vulnerability Delineation
  • 2. WHPA & Vulnerability Delineation
  • v = Ki/n = average linear velocity; where

K = hydraulic conductivity (constant of proportionality describing ease with which a fluid can move through a porous media) i = hydraulic gradient n = porosity

From Freeze & Cherry (1979)

Average linear groundwater flow velocity

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From Freeze & Cherry (1979)

Note range Higher K = Higher average linear groundwater flow velocity

K=hydraulic conductivity v = Ki/n

Hydraulic conductivity

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From Freeze & Cherry (1979)

i=hydraulic gradient; higher i = higher avg linear gw flow velocity v = Ki/n

Hydraulic gradient

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porosity

From Freeze & Cherry (1979) From Freeze & Cherry (1979) (<1%)

~30% ~15% >50%

n=porosity; higher n = lower avg linear velocity v = Ki/n

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Good Aquifer: v=Ki/n=(1e-4 m/s)*0.01/0.3 = 105 m/yr (avg linear flow velocity) note - fracture flow can be much higher (m/d)

Average linear groundwater flow velocity

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Contaminant Transport

  • Contaminants can move at the average linear

groundater flow velocity (e.g chloride) OR

  • Movement can be slower (e.g. sorption,

dispersion, diffusion according to concentration gradients, etc);

  • Decrease mass but not necessarily velocity

(e.g. dilution, radioactive decay, biodegradation, chemical reactions, ion-exchange, etc); and

  • Increase velocity (colloidal transport,

complexation, etc)

Contaminants interact w physical, chemical & biological system

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Groundwater Vulnerability (WHPA)

a) Delineate Vulnerable Area – WHPA (A,B,C, C1-10yr and D) b) Assign intrinsic vulnerability

  • 0-5yrs High, 5-25yrs Medium, >25yrs Low

Relative Intrinsic Vulnerability c) Overlay WHPA zones with Intrinsic Vulnerability to give Vulnerability Score d) Constructed pathways e) Uncertainty

Unsaturated till Saturated till Saturated aquifer

WAAT SAAT UZAT JHL ½ WAAT SWAT WWAT 2 year TOT (WHPA: A=100m; B=2yr

C=5yr and D = 25 yr)

d) Numerical GW Flow Modelling – WAAT/SAAT

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CTC SWP - Municipal Pumping Rates

500 1,000 1,500 2,000 2,500 3,000 3,500 4,000 4,500

C e d a r v a l e W e l l 1 A C e d a r v a l e W e l l 3 C e d a r v a l e W e l l 4 A P r i n c e s s A n n W e l l 6 L i n d s a y C

  • u

r t W e l l 4 t h L i n e W e l l A D a v i d s

  • n

W e l l 2 P r

  • s

p e c t P a r k W e l l E r i n W e l l 7 E r i n W e l l 8 H i l l s b u r g h W e l l H 2 H i l l s b u r g h W e l l H 3 O r a n g e v i l l e 5

  • 5

A O r a n g e v i l l e 6 O r a n g e v i l l e 7

  • P

a s s m

  • r

e O r a n g e v i l l e 8 A O r a n g e v i l l e 8 B O r a n g e v i l l e 8 C O r a n g e v i l l e 9 A

  • 9

B O r a n g e v i l l e 1 O r a n g e v i l l e 1 1 C a r d i n a l W

  • d

s W e l l 1 C a r d i n a l W

  • d

s W e l l 3 C

  • l

e s W e l l 1 I s l a n d L a k e W e l l 2 O b s e r v a t i

  • n

W e l l 2 A A l t

  • n

# 3 C a l e d

  • n

# 3 C a l e d

  • n

# 4 I n g l e w

  • d

# 2 I n g l e w

  • d

# 3 C h e l t e n h a m # 1 C h e l t e n h a m # 2 C a l e d

  • n

E a s t # 2 C a l e d

  • n

E a s t # 3 C a l e d

  • n

E a s t # 4 P a l g r a v e # 2 P a l g r a v e # 3 P a l g r a v e # 4 N

  • b

l e t

  • n

# 2 N

  • b

l e t

  • n

# 3 K l e i n b u r g # 2 K l e i n b u r g # 3 K i n g C i t y # 3 K i n g C i t y # 4 S t

  • u

f f v i l l e # 1 S t

  • u

f f v i l l e # 2 S t

  • u

f f v i l l e # 3 S t

  • u

f f v i l l e # 5 S t

  • u

f f v i l l e # 6 U x v i l l e

pumping rate (m3/d)

Lyndsay Court Orangeville 5-5A Palgrave 4 Stouffville 3,5 Cedarvale 4A Caledon East 4 Palgrave 3

~0.4 m3

2005/2006 municipal pumping rates

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Recharge = 15 mm/yr Q = 0, -1000, etc m3/d (x=y=5000m) 50m Kh/Kv(m/s) Ss (1/m)/Sy n

  • upper aquifer-a
  • 40m

10-4/10-5 1e-4/0.30 0.3 CH=50m

  • upper-aquifer-b
  • CH=41m

10-4/10-5 1e-4/0.30 0.3 CH=50m 30m lower aquitard 10m 10-8/10-9 1e-6/0.10 0.1

  • lower aquifer
  • CH=25m

10-4/10-5 1e-4/0.30 0.3 CH=45m 0m y=10,000 m

Numerical GW Flow Modelling – estimate travel times

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Lower aquifer;Q=1000 m3/d;25yr TOT Q=1000 m3/d Lower aquifer - steady state particle traces Q=2000 m3/d Upper aquifer;Q=1000 m3/d;25yr TOT Lower aquifer Q=2000 m3/d; 25yr TOT

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Upper aquifer; Q1000 m3/d; steady state particles Lower aquifer; Q1000 m3/d; steady state particles Lower aquifer; Q2000 m3/d; steady state particles Lower aquifer; Q1000 m3/d; 25yr TOT Lower aquifer; Q2000 m3/d; 25yr TOT No pumping ~450 m/25 yr ~1250 m/25 yr ~1550 m/25 yr

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Municipal Supply Wells & Intakes Wellington County

Lorne Park Lakeview R.L. Clark Toronto Island R.C. Harris Lakeview F.J. Horgan Whitby

  • 3. Peel Region (TRCA) WHPAs
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Surficial Geology (OGS) & Recharge East Cross Section West Cross Section

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Peel – Wellington Boundary Alton Airport Road Heart Lake Rd. Peel – York Boundary (Hwy #9) Palgrave

Section Location

Mount Wolfe Road

(Figure from Earthfx)

Hydraulic Setting #2 – ~ West Half

shallow aquifer ORM deep aquifer (TF) deep aquifer (Sc) Bedrock (shale) Bedrock (aquifer)

W E

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(Figure from Earthfx, October 17, 2007)

Observed groundwater levels Oak Ridges Aquifer Complex

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(Figure from Earthfx, October 17, 2007)

West Model extent

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(Figure from Earthfx, October 17, 2007)

a) WHPA from Time of Travel

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(Figure from Earthfx, October 17, 2007)

b) Natural intrinsic susceptibility

ISI (Intrinsic Susceptibility Index) = thickness x K-factor (sum for each unit above aquifer)

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(Figure from Earthfx, October 17, 2007)

Palgrave 2: 47m deep (permeable ORAC, shallow water table) Palgrave 3: 82 m deep (deeper water table, more silt in ORAC)

b) Natural intrinsic susceptibility

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(Figure from Earthfx, October 17, 2007)

b) Natural intrinsic susceptibility

CE4: 55m TAC CE3: 19m ORAC

  • Cl

CE2: 30m ORAC (GUDI)

  • Cl
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Note: only zones >6 can Have significant threat (Water Quality Risk Assessment)

  • Constructed pathways?

(private wells, pits/quarries, etc)

c) Vulnerability scoring

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(Figure from Earthfx, October 17, 2007)

c) Vulnerability scoring

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c) Vulnerability scoring

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  • 4. Conclusion/Future Tasks
  • 4. Conclusion/Future Tasks
  • Vulnerability (travel times) can be tested
  • Chemistry, isotopes, pumping tests, etc
  • Sentry wells
  • Confirm information & complete mapping
  • Consistency with HVA vulnerability
  • Anthropogenic constructed pathways
  • Uncertainty
  • Peer Review
  • Threats Inventory & Risk Assessment