the practical application of geology to the mitigation and regulation of isolated wetlands november...

The Practical Application of Geology to the

Mitigation and Regulation of Isolated Wetlands

November 6, 2012Geological Society of America

Charlotte, NC

Amy Keyworth, Rick Bolich and Evan KaneNCDENR, Division of Water Quality

Background

• Geographically isolated from surface water• The Clean Water Act of 1972

does not protect IWs

– 2001 – Solid Waste Agency of Northern Cook County (SWANCC)

– 2006 – Rapanos/Carabell

Background

• Wetland functions– Flood control– Erosion control– Surface water quality– Biodiversity– Unique functions – amphibian reproduction

• NC – regulate IWs since 2001Protect the function, and the presence

Isolated Wetlands Hydrologic Connectivity Study

Multidisciplinary EPA grant-funded study– Biology, Ecology, Hydrology, Water quality

• Our role – hydrologic connectivity to surface water

• Bonus – knowledge we can apply to existing regulatory programs

• Activities that we regulate that might affect the presence and function of IWs– Mine dewatering– Land application of wastewater

• What level of hydrogeologic assessment is necessary?

Today’s objective

Legend

newphysiography83m_region

PHYSIOGRAP

Blue Ridge Province

Inner Coastal Plain

Outer Coastal Plain

Piedmont Province

50 Miles

50 Miles

Blue Ridge Province

Piedmont Province

Coastal Plain

North Carolina

Bladen County Brunswick County

10 Miles

#####

#

##

Owens 19891:250,000

2 Miles

##

#

#

#

#

2 Miles

Weems 20111:100,000

2 Miles

##

#

#

#

#

2 Miles

Isolated Wetlands Hydrologic Connectivity Study

• Lessons learned– Stratigraphy– Hydrology

• Horizontal flow direction• Vertical gradient

Data Collection

• 44 cores• 72 monitoring wells• 3 pumping wells• 10 stream gaging stations• Water levels

– monthly point-in-time– 32 automatic data-loggers

• 3 Aquifer tests

Stratigraphic Conceptual Models

Isolated wetland Stream

ETP

Isolated wetland Stream

Dark gray clay layer

Sandy layer

Water Level

Sand at Site BL7

Isolated wetland Stream

Silt bodies at BL1

Silt body

Sandy layerWater Level

Dark gray clay layer

Silt confining layer at site BL6

Isolated wetland Stream

Unconfined aquifer

Confined aquiferUnconfined

aquifer

Silt body

Sandy layerWater Level

Dark gray clay layer

Elev

ation

(fe

et)

Distance (feet)0 600200 400

65

60

55

50

45

40

35

30

25

20

15

10

5

0

Interbedded sand and clay

Sandy layer

Clay chips

Unknown

Wood

Isolated wetland

Connected wetland

Lower K layer at site GS1

250 Feet

250 Ft

Site BL9 – cemented zones

Core site

Cemented zone

Isolated Wetland

Hydrology Results

500 ft

Flow direction Site BL7 - topographic control

#

#

#

####

Monitoring wells

Surface Water gaging

Flow direction

500 ft

#

Monitoring wells

Flow direction

Flow directionSite BL17 - radial

10/1

5/10

11/4

/10

11/2

4/10

12/1

4/10

1/3/

11

1/23

/11

2/12

/11

3/4/

11

3/24

/11

4/13

/11

5/3/

11

5/23

/11

6/12

/11

7/2/

11

7/22

/11

8/11

/11

8/31

/11

60

61

62

63

64

BL6-MW2 D and S

BL6-MW2d

BL6-MW2s

Wa

ter

Ta

ble

Ele

va

tio

n (

ft m

sl)

Vertical gradientUpward

10/1

5/10

11/4

/10

11/2

4/10

12/1

4/10

1/3/

11

1/23

/11

2/12

/11

3/4/

11

3/24

/11

4/13

/11

5/3/

11

5/23

/11

6/12

/11

7/2/

11

7/22

/11

8/11

/11

8/31

/11

73

74

75

76

77

BL17 - MW1D and S

BL17-MW1d

BL17-MW1s

Wa

ter

Ta

ble

Ele

va

tio

n (

ft m

sl)

Vertical gradientDownward

10/1

5/10

11/4

/10

11/2

4/10

12/1

4/10

1/3/

11

1/23

/11

2/12

/11

3/4/

11

3/24

/11

4/13

/11

5/3/

11

5/23

/11

6/12

/11

7/2/

11

7/22

/11

8/11

/11

8/31

/11

51

52

53

54

55

56

BL1 - MW1d and s

BL1-MW1d

BL1-MW1s

Wat

er T

able

Ele

vati

on

(ft

msl

)

Vertical gradientNo vertical gradient

Vertical gradientChanges with conditions

BL7-MW1D BL7-MW1S Precipitation

50

51

52

0

1

2

Aug SepApr May JulJun

Wat

er T

able

Ele

vatio

n (ft

msl

)

Hou

rly P

reci

pita

tion

(in)

BL7 - MW1D and S

What level of assessment is necessary?

10 Miles

#####

#

##

Owen 19892 Miles

##

#

#

#

#

2 Miles

Weems 20112 Miles

##

#

#

#

#

2 Miles

Conclusions

• Can’t assume a simple system• Scale matters• Detailed stratigraphic characterization

Sample site plan

Core locationMonitoring well location

Conclusions

• Can’t assume a simple system• Scale matters• Detailed stratigraphic characterization• Think local scale

Acknowledgements

• EPA Cooperative Agreement Number CD 95415809 and CWA Section 106

• Bladen Lakes State Forest• Turnbull Creek Educational State Forest• The Nature Conservancy

Contact Information

Amy.Keyworth@ncdenr.gov

Rick.Bolich@ncdenr.gov Evan.Kane@ncdenr.gov