Michigan AquifersNorthern Michigan Wastewater Treatment

Operators Annual Meeting

Lesa A. Bagby, GeoTrans, Inc.

IntroductionHydrogeology Overview

Water CycleGroundwaterAquifersGroundwater Quality Groundwater QuantityWater Well DesignGroundwater MovementPublic Water SupplyWellhead Protection

Examples of Michigan AquifersUnconfined Sand and Gravel - Southeastern MichiganConfined Sandstone – Southcentral MichiganConfined Limestone – Northern Michigan

Water Cycle

Open SystemSolar EnergyEndless CycleEvap0rationPrecipitationRunoff InfiltrationDischarge

Ice Caps and Glaciers2.14 % WW77.3 % FW0 % AFW

Groundwater

0.16 % WW

22 % FW98 % AFW

Oceans97.3 % WW0 % FW0 % AFW

Water Source

WW = World’s Water Supply

FW = World’s Fresh Water Supply

AFW = Available Fresh Water

What is Groundwater?

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Soil Moisture Unsaturated Zone (Vadose)• Water• Air• Used by plants

GroundwaterSaturated Zone (Phreatic)•Water•Total Saturation•Occurs in many types

of soil and rock•Used by People

AquifersAn aquifer is a geologic unit capable of storing and

producing groundwater of consumptive economic importance.

Types of AquifersFormation Type

Drift –Unconsolidated (Sand and Gravel)Bedrock – (Sandstone and Limestone)

Position in the Subsurface UnconfinedConfinedPerched

Drift Aquifers

• Drift is unconsolidated material

• Quality groundwater

• Thickest drift

• Clay drift

• Sand and gravel drift

Bedrock Aquifers

• Occur at the surface as well as under the drift

• Quality drinking water

• Primary porosity

• Secondary porosity

• Access

• Prolific bedrock aquifers

Unconfined Aquifers

Adapted from Manual of Applied Field Hydrogeology, Weight, Sonderegger, McGraw-Hill, 2001

Unsaturated Zone (Vadose)

Unconfined Aquifer

Confining Layer

Confined AquifersA confined aquifer has a barrier both above and below

These barriers are called confining layers

Confining layers are made up of geologic materials that greatly slow or restrict the movement of groundwater (such as clay)

Water pressure within a confined aquifer is higher than in an unconfined aquifer because of the weight of the overlying formations coupled with their confined nature (because the water cannot escape easily through the confining layers, pressure builds up).

Copyright © 2009 International Water Law Project | All Rights ReservedDesign by Sidebar Designs | Modified by Gabriel Eckstein

Perched Groundwater

In areas where a small confining layer is present, above the water table there may be perched groundwater

Since the volume of water held in these areas is minimal, they are generally not used as a source of drinking water

Water Table

Unconfined Aquifer

Confining Layer

PerchedGroundwater

Adapted from Applied Ground-water Hydrology and Well Hydraulics, Kasenow, Water Resources Publications, LLC, 1997

Groundwater QualityWater molecule

Dissolved substancesGeologic formationsSmall quantities

Water quality

Water quality standards

Maximum Contaminant LevelsDeveloped by the United States Environmental Protection Agency

Available at http://www.epa.gov/safewater/contaminants/index.html#listmcl

Provides:• The name of the regulated chemical

• The maximum concentration that the chemical is safe in drinking water

• The Potential Health Effects

• Sources of the Contaminant

• Secondary Contaminant Levels for chemicals that are safe to drink but would affect the taste, color or odor of the drinking water

Cleanup CriteriaDeveloped by the Michigan Department of Environmental Quality

Available at http://www.michigan.gov/deq/0,1607,7-135-3311_4109_9846-101581--,00.html

Water Quality Parameters and their SignificanceChemical Source Significance

Calcium and Magnesium

Dissolved from limestone and dolomiteFound in brines and sea water

Causes hardness and scale-forming properties of water

Sodium and Potassium

Dissolved from almost all rocks and soilsFound in ancient brines, industrial brines, sea water and sewageFound in rock salt used for deicing purposes

Causes salty taste in water, may cause foaming in steam boilers, may be harmful to persons on sodium-restricted diets

Iron and Manganese

Dissolved from almost all rocks and soils, contaminant plumes can increase the dissolution from the soil into the groundwater

Causes staining on laundry and fixtures, objectionable taste, interferes with efficiency of water softeners

Water Quality Parameters and their Significance continuedChemical Source Significance

Bicarbonate and Carbonate

Action of carbon dioxide on water on carbonate rocks like limestone and dolomite

Produces alkalinity, may form scale and may release carbon dioxide gas in steam boilers

Chloride Dissolve from rocks and soilsFound in ancient brines, industrial brines, sea water and sewageFound in rock salt used for deicing purposes

Causes salty taste in water, may increase corrosive activity of water

Sulfate Dissolved from rocks and soils that contain gypsum, iron sulfides, and other sulfur compoundsFound in industrial waste

Forms hard scale in steam boilers, gives bitter taste to water, can be beneficial in the brewing process

Water Quality Parameters and their Significance continuedChemical Source Significance

Nitrate Decaying organic material, sewage, nitrates in soil, fertilizers

Sign of pollution in individual wells, not usually entire aquifers, promotes algae growth and affect taste of water, may cause methemoglobinemia (Blue Babies) in infants which can be fatal

Hydrogen Sulfide

Natural decomposition of organic material

Causes objectionable odor and taste

Trace Metals(like Arsenic)

Dissolved from rocks and soil, may be released from plumbing piping, may be released in the presence of organic material (wetlands)

Causes adverse health affects at certain levels

Maximum Contaminant Level For Arsenic10 ug/L

Maximum Contaminant Level For Nitrate10 mg/L

Saline and Brine Groundwater

Secondary Drinking Water Regulatory Level For Total Dissolved Solids500 mg/L

Water QuantityGenerally, two aquifer properties are used to

evaluate the quantity of water that can be produced from an aquifer:Hydraulic Conductivity - Three-dimensional flow

represented by a unit cube Aquifer Thickness – Thickness of the zone of

saturation

Transmissivity is also used to described an aquiferTransmissivity – Hydraulic conductivity multiplied

by aquifer thickness and is a two-dimensional flow represented flow represented by a unit prism

Water Quantity continuedRules of thumb

The thicker the aquifer the more water will be available for withdrawal relative to thinner aquifers of the same material

For unconsolidated aquifers, the coarser the material the higher the Hydraulic Conductivity and subsequently the more water that will be available for withdrawl

For bedrock aquifers, fractured rock can produce significantly more water than unfractured rock

Silts, clays and shales have low Hydraulic Conductivity and would supply single households, if any

Applied Ground-Water Hydrology and Well Hydraulics, Kasenow, Water Resources Publication, LLC, 1997

Water Quantity continuedClassification of Transmissivity by Magnitude

TransmissivityGallons per day per foot

Class Meaning Supply Potential

120,000 I Exceptional A Natural Resource

80,500 II Very High Of Great Regional Importance

8,050 III High Of Regional Importance

805 IV Intermediate Of Local Importance

80.50 V Low Of Local Value

8.05 VI Very Low Limited to Private Supplies

<8.05 VII Imperceptible Probably Not an AquiferModification of Krasny’s classification, Applied Ground-Water Hydrology and Well Hydraulics, Kasenow, Water Resources Publication, LLC, 1997

Water Well ConstructionInstallation methods

Dug

Drilled

Driven

Well screensKeeps solids out of well

Open boreholesBedrock wells

Sealing ancillary space

Typical well depths

Groundwater MovementInfluences on movement

TemperatureSoil TypeGeology

Rate of movementGenerally slow, 3-4 feet per day in sand, inches per

day in clayDirection of movement

High pressure to low pressureVertical Lateral

Groundwater flow maps

Darcy Groundwater Movement Model, Version 2

Vertical Cross Section of Groundwater Flow

Plan View of Groundwater Flow

Calculate Groundwater Elevations

Measure depth to water

Subtract from top of well casing elvevation

Estimate Groundwater Elevation Contours

Interpolation between known elevations

Direction of Horizontal Flow

Perpendicular to the groundwater elevation contours

Applied Ground-Water Hydrology and Well Hydraulics 2nd Edition, Kasenow, Water Resources Publication, LLC2001

Public Water SupplyThree types in the State of Michigan

Type IType IIType III

Type I Hydrogeologic Evaluation RequirementsAquifer Characteristics

Transmissivity Direction of Groundwater Flow Safe Yield

Water Quality

Michigan Type I Wells and Aquifer Test Locations

Wellhead ProtectionVoluntary program to protect public

water supplyElements of Wellhead Protection

ProgramRoles and ResponsibilitiesWellhead Protection Area DelineationPotential Sources of ContaminationWellhead Protection Area ManagementContingency PlanNew WellsUpdates to the Plan

Map or list of Wellhead Protection Communities

Wellhead Protection Areas in Lower Michigan

ReviewHydrogeology Overview

Water CycleWhat is Groundwater?AquifersWater Quality Water QuantityWater Well DesignGroundwater MovementPublic Water SupplyWellhead Protection

Examples of Michigan AquifersSemi-Confined Sand and Gravel - Southeastern

MichiganConfined Sandstone – South-central MichiganConfined Limestone – Northern Michigan

Semi-confined Sand and Gravel

Semi-confined Sand and GravelAquifer

Semi-confined Sand and Gravel Aquifer

Well Field

Semi-Confined Sand and GravelLocation City in Southeastern Michigan

Aquifer Unconfined to Semi-confined sand and gravel from surface grade to a depth of 100-feet. Depth to water is 45-feet, therefore the aquifer thickness is 55-feet

Water Quality Trace volatile organic compounds. Source of chemicals from nearby industrial properties. Water treatment includes an air stripper to remove volatile organic compounds from the water supply

Water Quantity

Estimated transmissivity is 31,000 gallons per day/foot which indicates the aquifer is of regional importance

Water Well Design

Well field has two wells. Wells are comprised of 12-inch diameter well casings and well screens. The average pump rate for the wells is 180 gallons per minute

Confined Sandstone Aquifer

Confined Sandstone Aquifer

Confined Sandstone AquiferDown-hole Video

Confined Sandstone AquiferLocation Services portions of four townships in south-

central Michigan: Marion, Howell, Oceola and Genoa

Aquifer Confined sandstone (Marshall Sandstone) from a depth of 120 feet to 420 feet. Depth to water is 32-feet which is higher than that of the top of aquifer demonstrating the confined nature of the aquifer.

Water Quality Very good. Treatment is limited to chlorination and water softening.

Water Quantity

Estimated transmissivity is 200,000 gallons per day/foot which indicates the aquifer is an exceptional natural resource

Water Well Design

Well field has six wells. Wells are comprised of 12-inch diameter well casings and open boreholes. Average pump rates are 1,400 gallons per minute with an average withdrawal of 1 MGD.

Confined Sandstone AquiferLocation Services portions of four townships in south-

central Michigan: Marion, Howell, Oceola and Genoa

Aquifer Confined sandstone (Marshall Sandstone) from a depth of 120 feet to 420 feet. Depth to water is 32-feet which is higher than that of the top of aquifer demonstrating the confined nature of the aquifer.

Water Quality Very good. Treatment is limited to chlorination and water softening.

Water Quantity

Estimated transmissivity is 200,000 gallons per day/foot which indicates the aquifer is an exceptional natural resource

Water Well Design

Well field has six wells. Wells are comprised of 12-inch diameter well casings and open boreholes. Average pump rates are 1,400 gallons per minute with an average withdrawal of 1 MGD.

Confined Limestone Aquifer

Confined Limestone AquiferPlan View

Confined Limestone AquiferLocation Petoskey, Michigan

Aquifer Confined limestone (Traverse Limestone) as much as 580 feet thick and highly fractured. Depth to water is above the top of aquifer demonstrating the confined nature of the aquifer.

Water Quality Very good. Treatment is limited to chlorination.

Water Quantity

Estimated transmissivity is 22,000 gallons per day/foot which indicates the aquifer is of regional importance

Water Well Design

There are 4 well field with 1 production well in each well filed. Wells are comprised of 12-inch diameter well casings and open boreholes. Average pump rates are 1,000 gallons per minute with an average withdrawal of 3 MGD.