How To Describe or How To Describe or Identify Water Levels Using Identify Water Levels Using

Soil MorphologySoil Morphology

Prepared by Mr. Brian Oram, Professional Geologist, Soil Scientist

Wilkes UniversityEnvironmental Engineering and Earth Sciences Department

84 West South StreetWilkes Barre, PA 18766

http://www.water-research.net

How to determine the Height of the How to determine the Height of the Seasonal High Water Table Seasonal High Water Table

But first we must decide what we are really want to know and

our application.

• Sewage Applications PA – Evidence of Redoximorphic Features

• Stormwater Applications – Evidence of Saturation

These are the same ?

No- Redoximorphic features indicates the zone is saturated and

anaerobic and meet all the other requirements for the creation

of these features.

Seasonal High Water Table Seasonal High Water Table Wastewater ApplicationWastewater Application

• Presence of Redoximorphic Features• Direct Observation• Monitoring• Modeling and Water Budget Analysis

Current Law: Pennsylvania Current Law: Pennsylvania Land-Based DisposalLand-Based Disposal

• Presence of Redoximorphic Features• Direct Observation• This methodology requires the

preparation of detailed soil morphological descriptions.

Current Law: Current Law: Pennsylvania Pennsylvania Land-Based Land-Based

DisposalDisposal

Saturated Soil- Ponded Water

Redoximorphic Features (m2p)

Endosaturation – observed redoximorphicfeatures (f2d to m2p) and direct observation of saturated condition.

This means that the soil is saturated andanaerobic to create redoximorphic featuresat a depth of approximately 2 feet

Because the redoximorphic features are moreprominent it may be assumed that the soils is saturated and anaerobic for longer periods of time.

Depth to Water Table

Redoximorphic Features (f2f)

2 feet

Monitoring Monitoring DevicesDevices

Piezometer – Solid Pipe that is only open at the bottom or a discrete or very small interval

Well – Is a solid pipe that is Perforated or slotted over an interval.

Open at the bottomOpen Over anInterval

Measures the Piezometeric pressureat a discrete point

Measures the Average PiezometericPressure over a largerInterval – Measures water table depth underUnconsolidated near horizontal flow

Monitoring Monitoring DevicesDevices

Direction of Groundwater Flow

Lines of Equal Potential

100 ft 90 feet 80 feet

GroundwaterGradient =

dh/dl = 10 feet/100 feetdh/dl = 0.10 ft/ft

Monitoring Monitoring DevicesDevices

Direction of Groundwater Flow

Lines of Equal Potential

80 feet

GroundwaterGradient (Use Piezometers)=

dh/dl = (125 – 60)/100dh/dl = - 0.65 ft/ft

105

80

60

Datum

MaterialSaturated

60 feet

75

(100 feet)

120 feet

100100 feet

Monitoring Monitoring DevicesDevices

Direction of Groundwater Flow

Lines of Equal Potential

80 feet

100 feet

GroundwaterGradient (Use Piezometers)=

dh/dl = (120 ft -90feet)/50 feetdh/dl = 0.60 ft/ft

Datum

MaterialSaturated

120 feet

(100 feet)

120

100

90

105

80

MonitoringMonitoring

Direct Observation

Where is the Seasonal High Water Table?

Based on the presence of Redoximorphic features (f1f) Depth to Water Table = 2 feet

Based on Monitoring – SHWT wasOnly 1.5 feet below grade.

What ? Why is it 0.5 feet higher?Possible Answer- The water is not Anaerobic from 1.5 to 2.0 feetPore Water Anaerobic at > 2.0 feet

1.75 ft2.0 ft

Methods of Determining Wetness Methods of Determining Wetness Used by State AgenciesUsed by State Agencies

Method Number

Mottles (any color) 13

Monitoring Only 6

Mottles < 2 chroma 6

Redoximorphic 5

Soil Drainage Class 1

Soil Color 3

Soil Evaluation 1

Compiled by: Dr. Mike Vepraskas, NC State University

CompareCompareFour MethodsFour Methods

Variegated Colors- May or may not be Redox related. SHWT at 1.0 feet

Monitoring – One Year Monitoring – 1.75 feet

Pennsylvania (Redoximorphic Features)SHWT at 2 feet

North Carolina and Others (low chorma > 50% of matrix ) SHWT at 4 feet

SHWT – Seasonal High Water Table.

Redoximorphic Features (f2f)Depletions chorma > 2

For Land-Based Wastewater Disposal inPA – SHWT at 2 feet

Redoximorphic Features (m2p)Depletions chorma < 2

This is Just the Tip of the This is Just the Tip of the Iceberg !!!Iceberg !!!

There are a lot of other issues, such as:

• How does the lack of decomposable organic material limit the formation of redoximorphic features ?

It is possible that the material is saturated and anaerobic, but this does not meet all conditions for formation of redoximorphic features.

• How long is the material saturated and anaerobic? The presence of redoximorphicfeatures does not tell us how long the soil is saturated or anaerobic.

• Monitoring water level may suggest saturated conditions, but it is critical tounderstand hydrogeology, direction of groundwater flow (recharge, discharge, orHorizontal flow).

How To Describe or How To Describe or Identify Water Levels Using Identify Water Levels Using

Soil MorphologySoil Morphology

Prepared by Mr. Brian Oram, Professional Geologist, Soil Scientist

Wilkes UniversityEnvironmental Engineering and Earth Sciences Department

84 West South StreetWilkes Barre, PA 18766

http://www.water-research.net