Erik Severson, Research Associate and Interpretive Soil
Scientist, CSES department, Virginia Tech
Well
Aerobic soil
Groundwater
Trench Bottom
Clayton Site
Left Side – Lateral 3
8/23/1999
Coarse-Textured
Clayey Horizon
Source: Aziz Amoozegar, Lake Wheeler
Introduction
F
Flat Topography +
Impermeable Layers
=
Perched Water Tables
1.
Document morphology and monitor
saturation in the Appomattox and
Bentley Soil Series.
2.
Calculate % wet season RMFs were
saturated.
3.
Confirm or deny epiaquic conditions.
4.
Compare saturation differences of
entirely residual soils versus transported
soils.
Location 1:
Bentley Soils
Location 2:
Residual Soil
Appomattox
Bentley
Cap and vent hole
Annulus
Bentonite
Slotted
pipe
gravel
Solid pipe
Restrictive
Layer
30-day
40
Average
50
60
Depth (cm)
0
10
20
30
70
20-day
80
90
100
4/30
4/23
4/16
4/9
4/2
3/26
3/19
3/12
3/5
2/26
2/19
2/12
2/5
1/29
1/22
1/15
1/8
1/1
0
10
20
Depth (cm)
30
40
Iron
Concentrations:
5%
50
60
70
80
Chroma 3 depleted ped
90
faces
65%
100
4/30
4/23
4/16
4/9
4/2
3/26
3/19
3/12
3/5
2/26
2/19
2/12
2/5
1/29
1/22
1/15
1/8
1/1
1) Document Soil Morphology
And
2) Monitor saturation for the
Appomattox and Bentley Soils
Ap
Bt1
Bt2
2BCt
3CBt
3Ct
0
200
180
-20
160
Depth (cm)
120
-60
100
80
-80
60
40
-100
20
-120
Oct-11
0
Mar-12
5YR 5/8 (c)
Aug-12
10YR 7/8 (d)
Jan-13
Jun-13
10YR 7/4 (d)
Nov-13
N/8 (d)
Apr-14
Precipitation
Precipitation (mm)
140
-40
Depleted ped faces
n =36
Concentrations
n=11
≥3 chroma depletions
n=20
≤2 chroma depletions
n=12
41%
23%
41%
65%
0
-50
Depth (cm)
-100
-150
-200
Perching confirmed at
6 out of 8 sites
-250
-300
-350
Sep-11
Apr-12
Oct-12
1.5M
3M
May-13
Discontinuity
Nov-13
Jun-14
 Compare hydrology of entirely
residual soils vs. transported soils
at same depths (1 m).
0
-20
Depth (cm)
-40
-60
-80
-100
-120
Nov-12
Mar-13
Jul-13
Residual
Nov-13
Transported
Mar-14
Soils
Avg. Water Table
30-day
20-day
Transported
81
64
91
Residual
95
83
--
Conclusions
Transported
soils perch
water for
extended
periods on
impermeable
layers.
Conclusions
Redox
Features
with
chroma ≥3
indicate a
fluctuating
water table.
Conclusions
Residual
soils
underneath
transported
soils were
not
saturated.
Conclusions
Entirely
residual
soils were
“drier” than
transported
soils.

Avoid use of transported soils with
restriction and perched water table

Avoid 1 M below lithologic discontinuity