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.

Monitoring wells may be unreliable in detecting contaminant release.

Simulated Underground Storage Tank Pit Trace Date- January 26, 2005 Weather- Dry Springs- At low base flow 8 pounds of 40% Fluorescein 500 gallons of flush water Results 1 well detection, weakly positive. 4 Days

Simulated Underground Storage Tank Pit Trace Date- January 26, 2005 Weather- Dry Springs- At low base flow 8 pounds of 40% Fluorescein 500 gallons of flush water Results 1 well detection, 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, 2005 Weather- Dry Springs- At low base flow 8 pounds of 40% Fluorescein 16 pounds of 20% Rhodamine-WT 500 gallons of flush water Results 1 well detection, weakly positive. 4 Days Garrison, Idstein, and Ewers (2006)

Fluorescein traversed 6.3 miles in 4 days. Eosine appeared 2.8 miles south 3 days after injection. Eosine traversed 6.3 miles in 5 days, 3 days before it appeared sporadically in a monitoring well 100 feet distant. Simulated Underground Storage Tank Pit Trace

Water levels measured in wells often give erroneous indications of groundwater flow direction.

N=12 N=43 N=30 N=33 N Transmissivity between1.1 x m 2 /s and 1.9 x m 2 /s Ewers, White, Paschl, and Hannish (2005)

N=12 N=43 N=30 N=33 N Transmissivity between1.1 x m 2 /s and 1.9 x m 2 /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.

Head fluctuations in wells in response to nearby pumping do not necessarily indicate flow connections.

Solvent Pit Dye Injection Well Pumped Well – Intended Remediation Well Long-Term TCE Release Site – Tool Manufacturing Facility 60 ft.

Solvent Pit Dye Injection Well Pumped Well – Intended Remediation Well Long-Term TCE Release Site – Tool Manufacturing Facility Well Pumped For 20 Days

Solvent Pit Dye Injection Well Pumped Well – Intended Remediation Well Long-Term TCE Release Site – Tool Manufacturing Facility To Spring 3000 ft Distant No Dye Detected

Dye Injection Well Pumped Well – Intended Remediation Well Long-Term TCE Release Site – Tool Manufacturing Facility Increased Flow Decreased Flow

Dye Injection Well Pumped Well – Intended Remediation Well Long-Term TCE Release Site – Tool Manufacturing Facility A PRESSURE CONNECTION IS NOT NECESSARILY 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