on the efficacy of monitoring wells in karstic carbonate aquifers
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On The Efficacy of Monitoring Wells in Karstic Carbonate Aquifers. Ralph O. Ewers, Ph.D. On The Efficacy of Monitoring Wells in Karstic Carbonate Aquifers or. How Not to Diagnose Contaminant Problems in Karst Ralph O. Ewers, Ph.D. - PowerPoint PPT PresentationTRANSCRIPT
On The Efficacy of Monitoring Wells in Karstic
Carbonate Aquifers
Ralph O. Ewers, Ph.D.Ralph O. Ewers, Ph.D.
On The Efficacy of Monitoring Wells in Karstic
Carbonate Aquifersor
How Not to DiagnoseHow Not to Diagnose
Contaminant Problems Contaminant Problems
in Karstin KarstRalph O. Ewers, Ph.D.Ralph O. Ewers, Ph.D.
Monitoring wells may be unreliable in detecting contaminant release.
Simulated Underground Storage Tank Pit Trace
Date- January 26, 2005Date- January 26, 2005
Weather- DryWeather- Dry
Springs- At low base flowSprings- At low base flow
8 pounds of 40% Fluorescein8 pounds of 40% Fluorescein
500 gallons of flush water500 gallons of flush water
Results 1 well detection, Results 1 well detection, weakly positive. weakly positive.
4 Days
Simulated Underground Storage Tank Pit Trace
Date- January 26, 2005Date- January 26, 2005
Weather- DryWeather- Dry
Springs- At low base flowSprings- At low base flow
8 pounds of 40% Fluorescein8 pounds of 40% Fluorescein
500 gallons of flush water500 gallons of flush water
Results 1 well detection, Results 1 well detection, weakly positive. weakly positive.
4 Days
1 Chance in 8
A monitoring well that detects a contaminant is
unlikely to provide appropriate data regarding the quantity of the release or the speed and direction
of the contaminant movement.
Simulated Underground Storage Tank Pit Trace
Date- January 26, 2005Date- January 26, 2005
Weather- DryWeather- Dry
Springs- At low base flowSprings- At low base flow
8 pounds of 40% Fluorescein8 pounds of 40% Fluorescein
16 pounds of 20% Rhodamine-16 pounds of 20% Rhodamine-WTWT
500 gallons of flush water500 gallons of flush water
Results 1 well detection, Results 1 well detection, weakly positive. weakly positive.
4 Days
Garrison, Idstein, and Ewers (2006)
Fluorescein traversed 6.3 Fluorescein traversed 6.3 miles in 4 days.miles in 4 days.
Eosine appeared 2.8 miles Eosine appeared 2.8 miles south 3 days after south 3 days after injection.injection.
Eosine traversed 6.3 miles Eosine traversed 6.3 miles in 5 days, 3 days before it in 5 days, 3 days before it appeared sporadically in a appeared sporadically in a monitoring well 100 feet monitoring well 100 feet distant. distant.
Simulated Underground Storage Tank Pit Trace
Water levels measured in wells often give erroneous indications of groundwater
flow direction.
N=12N=12
N=43N=43
N=30N=30
N=33N=33
NN
Transmissivity between1.1 x 10-5 m2/s and 1.9 x 10-5 m2/s
Ewers, White, Paschl, and Hannish (2005)
N=12N=12
N=43N=43
N=30N=30
N=33N=33
NN
Transmissivity between1.1 x 10-5 m2/s and 1.9 x 10-5 m2/s
Groundwater Velocity at Least 9 m/hr in Conduits
4.2 Miles
Well water levels taken at traditional calendar
intervals give little insight into the fluctuations that
the well presents.
70 80 90 100Ju lian D ate
200
250
300
350
400
450
Co
nd
uctiv
ity (
mic
ro m
ho
s)
80
120
160
200
240
280
Sta
ge
(Fee
t M
SL
)
13 .2
13.6
14
14.4
14.8
15.2
Te
mp
erat
ure
(C
els
ius)
M ills tone Spring
Head fluctuations in wells in response to nearby
pumping do not necessarily indicate flow
connections.
Solvent Pit
Dye Injection WellPumped Well – Intended Remediation Well
Long-Term TCE Release Site – Tool Manufacturing Facility
60 ft.
Solvent Pit
Dye Injection WellPumped Well – Intended Remediation Well
Long-Term TCE Release Site – Tool Manufacturing Facility
Well Pumped For 20 Days
Solvent Pit
Dye Injection WellPumped Well – Intended Remediation Well
Long-Term TCE Release Site – Tool Manufacturing Facility
To Spring 3000 ft Distant
No Dye Detected
Dye Injection WellPumped Well – Intended Remediation Well
Long-Term TCE Release Site – Tool Manufacturing Facility
Increased Flow
Decreased Flow
Dye Injection WellPumped Well – Intended Remediation Well
Long-Term TCE Release Site – Tool Manufacturing Facility
A PRESSURE CONNECTION A PRESSURE CONNECTION IS NOT NECESSARILY IS NOT NECESSARILY A FLOW CONNECTION A FLOW CONNECTION
TRADITIONAL WELL TESTS IN CARBONATE AQUIFERS TYPICALLY DO NOT SENSE
THE MOST IMPORTANT ELEMENTS OF THE
PERMEABILITY STRUCTURE.
(Quinlan, Worthington and Davies, 1992; Teutsch and Sauter, 1992; Worthington, 1992)
Virtually every well in a carbonate aquifer is
influenced by a unique suite of permeability and
recharge elements.
Johnson and Ewers (1994)Recker and Ewers (1990)
Each well responds to storm events differently, with no apparent relation to distance from the conduit.
MONITORING WELLS ARE
UNRELIABLE IN KARST