Groundwater and Wells - Illinois State Water Survey

Groundwater and Wells: An Introductory Discussion with Application to Northeastern Illinois

H. Allen Wehrmann, P.E. Illinois State Water Survey Illinois Department of Natural Resources

2007 Priority Places Workshop: Implementing a Sustainable Water Supply for Kane County’s Future

Topical Presentation Outline Basic Concepts and Definition

The Hydrologic Cycle What

Is Groundwater?

Concepts and Definitions Porous

Flow vs. Fractured Flow Aquifers vs. Aquitards Artesian vs. Water Table Conditions

Regional Groundwater G Flow Systems S Well and Aquifer Hydraulics


The Water Cycle Climate, surface water, and groundwater are linked


Porous Systems Groundwater flows through pore spaces between grains


Fractured Systems


Fractured Limestone or Dolomite


Aquifers vs. Aquitards

An aquifer is a saturated bed, formation, or group of formations that yields water in sufficient quantity to be of consequence as a source of supply.

An aquitard yields inappreciable quantities of water, but leakage of water through the aquitard is possible. Aquitards often act as confining beds.


Unconfined vs. Confined Groundwater

An unconfined aquifer is one in which groundwater possesses a free surface open to the atmosphere. The upper surface of the zone of saturation is called the water table.

A confined fi d aquifer if is i one iin which hi h groundwater d t iis confined under pressure by overlying and underlying aquitards or aquicludes, and water levels in wells rise above b th the ttop off the th aquifer. if A confined fi d aquifer if is i also l called an artesian aquifer.


Unconfined Aquifers Land Surface Unsaturated ((Vadose)) Zone Water Table

Saturated Zone Unconfined Aquifer

Bedrock


Confined Aquifers Land Surface Unsaturated (Vadose) Zone Water Table

Unconfined Aquifer

Saturated Zone

Potentiometric Surface

Confining Layer - Aquitard

Confined Aquifer

Bedrock


Confined Aquifers and Artesian Wells Flowing artesian well Land surface

Confining layer

Confined Aquifer f


Regional Groundwater Flow Systems 0.1 mile 20 miles

Depth

0’

100’ 10’

200’ 20’ 2007 Priority Places Workshop: Implementing a Sustainable Water Supply for Kane County’s Future

Cone of Depression


Overlapping Cones of Depression


Overlapping Cones of Depression: Well Interference








Potentiometric S f Surface off the th Deep Bedrock A if S Aquifer System, t Fall 2000


Potentiometric Surface across NE Illinois WEST

EAST

Elevation (ft)

Elevation (ft)

1000

1000

DeKalb 800

Elburn Geneva

800

Elmhurst Bellwood

Industrial site in Chi cago

600

600

400

400

200

200

0

St. Peter

0

Ss

- 200

-200

- 400

-400

- 600

- 800

Ironton -Galesviil le

Ss

-600

-800

-1000

-1000

-1200

-1200


Deep Well Water Levels Levels, Cook County


Deep Well Water Levels, Kendall County 600

Ellevation abov ve Sea Level (feet)

500

400

300

200

100

Oswego #3 0 1950

1960

1970

1980

1990

2000


Water Sources for Public Supply in Northeast Illinois
