Culvert Scour Assessment
Pine Creek
Site Information
Site Location:
Willamette NF, Road 21
Year Installed:
Circa 1999
Lat/Long:
122°27”21.67”W
Watershed Area (mi2): 1.91
43°33’16.38”N
Stream Slope (ft/ft) : 0.062
Channel Type: Step-pool
Bankfull Width (ft):
Survey Date:
1
1
13
March 21 2007
Water surface slope extending up to 20 channel widths up and downstream of crossing.
Culvert Information
Culvert Type:
Pipe arch
Culvert Material:Annular CMP
Culvert Width:
13
Outlet Type:
Mitered
Culvert Length:
60 ft
Inlet Type:
Mitered
Pipe Slope (structure slope): 0.05
Culvert Bed Slope: 0.038
(First hydraulic control upstream of inlet to first hydraulic control downstream of outlet.)
Culvert width as a percentage of bankfull width: 1.03
Alignment Conditions: Inlet appears to be further south than natural channel alignment. Bank scour
on right bank upstream of inlet may be partially related to alignment.
Bed Conditions: Large cobble/boulder steps in upstream end of pipe.
Pipe Condition: Structure joints open in places on culvert walls. Cannot see pipe bottom.
Hydrology
Discharge (cfs) for indicated recurrence interval
25% 2-yr
2-year
Qbf2
5-year
10-year
50-year
100-year
15
58
65
91
113
165
188
2
Bankfull flow estimated by matching modeled water surface elevations to field-identified bankfull elevations.
A—358
Pine Creek
Site Evaluations
Points represent survey points
Figure 1—Plan view map.
Pine Creek
A—359
Culvert Scour Assessment
History
The Pine Creek culvert was installed in 1999.
Bed material was placed inside the culvert during
construction. The gradation used was similar to
the upstream channel. Pebble counts following
construction revealed similar D84 and D16, and
low D50 compared to the upstream channel. Very
few fines were present. No bed material sorting,
bedform construction, or bank construction was
performed.
As for horizontal alignment, the culvert was
centered in the existing channel. For vertical
alignment, the pipe was placed intermediate
between the upstream and downstream profiles.
Following construction, about 50 percent of the
placed bed material scoured out of the structure
but sediments redeposited within the pipe, raising
the bed to near the constructed-bed elevation.
In addition, channel sediment that aggraded
upstream of the culvert transported through the
structure.
No significant maintenance has occurred at the
site since construction.
The above information was furnished by
Kim Johansen, USFS.
An assessment of nearby stream gauges
suggests that nothing more than a 5-year
recurrence interval event has occurred in the
region since construction.
Pine Creek culvert post construction (Fall 1999, Kim
Johansen, U.S. Forest Service).
The previous culvert at this site was included
in the 1987 Western Federal Lands Highway
Division (WFLHD) “Oregon Culvert Fish Passage
Survey.” The field survey for the WFLHD
study was conducted on December 1, 1987.
The previous culvert was a 7.5-foot-diameter
corrugated metal pipe with an additional 36-inchdiameter pipe installed for flood relief. Oregon
Department of Fish and Wildlife (ODFW) staff
rated the previous culvert as a “good” installation
for fish passage but WFLHD staff noted high
velocities (nearly double that of the natural
channel) and a 2- to 3-foot-deep scour hole, and
considered the pipe to not be a good installation
for fish passage.
The following are photos of the previous culvert
from the WFLHD study:
Culvert inlet.
A—360
Pine Creek
Site Evaluations
Typical stream channel.
Site Description
The Pine Creek culvert is a large bottomless
arch mitered to conform to the roadfill. The site
is characterized by a high-gradient step-pool/
cascade channel extending approximately 50 feet
upstream of the inlet. The high gradient flattens
out as it enters the culvert. A steep riffle/step at
the entrance transitions into a relatively flat scour
pool along the right footing. Grade drops off again
downstream of the outlet, which soon enters the
broader flood plain of the Middle Fork Willamette
River.
Two upstream representative reaches were
identified at the site; a lower gradient upper one
and a steeper lower one. A long cascade and
wood jam separate representative reach one
(downstream) from representative reach two
(upstream). Below this cascade, representative
reach one consists of a series of steps and
pools. Large fallen trees are present through this
reach, generally along the banks and flood plain.
Gradient through this reach is much higher than
that found through the culvert or in representative
reach two.
Upstream of the cascade, reference reach two
runs through a series of riffles, pools, and steps.
As a flatter reach, this segment of channel is
wider with bars of gravels and some cobbles. A
similar flood-plain surface exists as that found in
the lower representative reach. Large fallen trees
also line the banks and have a small influence in
the channel.
Pine Creek
Survey Summary
Sixteen cross sections and a longitudinal profile
were surveyed along Pine Creek in March 2007
to characterize the culvert and two upstream
reference reaches. In the culvert, representative
cross sections were taken along a step and
through a pool. Two additional cross sections
were surveyed upstream to characterize the
inlet as well as the contraction of flow. Another
two cross sections were surveyed downstream
of the culvert to characterize the outlet and the
expansion of flow.
Representative cross sections in representative
reach one were taken through a step and a
pool. An additional two sections were taken to
characterize the upstream and downstream
boundaries of the reach. Representative cross
sections in representative reach two were also
taken through a step and a pool. An additional
two sections were taken to characterize the
upstream and downstream boundaries of the
reach.
Profile Analysis Segment Summary
The profile analysis resulted in a total of 10 profile
segments. Two segments with similar gradients
upstream of the inlet were not combined in order
to separate out the inlet transition segment
for analysis. The culvert consisted of two
profile segments. The downstream segment
in the culvert had comparable gradient to two
representative profile segments in the upstream
channel. There was no suitable comparison
segment for the upstream segment in the culvert.
The upstream transition segment had comparable
gradient to two representative profile segments in
the upstream channel. The downstream transition
segment had comparable gradient to three
upstream representative segments. See figure 2
and table 1.
A—361
Culvert Scour Assessment
Scour Conditions
Observed conditions
Footing scour – At least half and possibly as
much as all of the originally placed material was
scoured out of the pipe after construction. At the
time of the survey there was scour to the culvert
base at the inlet. The culvert base was exposed
for 4 feet. The scour was concentrated on the left
bank. The thalweg was along the left edge of the
pipe at the inlet (for 10 feet) and along the right
edge in the downstream half of the pipe.
Culvert-bed adjustment – Most, if not all, of the
original bed material installed in the culvert has
scoured out (see photo of post-construction
conditions in History section). Bed material has
aggraded adjacent to the scour pool along the
right bank and through the lower two-thirds of the
pipe resulting in a relatively flat bed. The slope of
the culvert bed has been reduced through scour
and aggradation (assuming the original culvert
bed was constructed at the same slope as the
structure).
Profile characteristics – The profile has a concave
shape through the crossing, with the maximum
concavity focused near the inlet (figure 2). This
shape reflects the inlet scour and upstream
channel incision combined with aggradation
in the downstream portion of the channel and
downstream of the outlet.
Residual depths – The upstream culvert segment
(C) residual depth is greater than any residual
depth found in the natural channel (figure 21).
This is the location of inlet scour. Residual
depth in the downstream portion of the culvert
(B) is within the range of residual depths in
corresponding profile segments (G and J).
Residual depth in the downstream transition
segment (A) is within or above the range of
depths in corresponding profile segments in the
natural channel (G, H, and J). Residual depth
A—362
in the upstream transition segment (D) is within
the range of depths in corresponding profile
segments in the natural channel (E and H).
Substrate – The bed material distribution in the
riffle in the culvert is similar to the bed material
in the step in representative channel reach one
(downstream) but coarser than the riffles in
representative channel reach two (upstream). The
bed material distribution in the glide in the culvert
is similar to the glide in representative channel
reach one. Culvert bed material sorting values
diverge only slightly from the range of values
found in the natural channel (table 7). Pebble
count data is provided at the end of this summary.
Predicted conditions
Cross-section characteristics – Hydraulic
modeling estimates that the culvert reduces
flow area, top width, and wetted perimeter but
increases hydraulic radius and depth (figures 5
through 7 and 12 through 19). These impacts
are apparent even at the lowest modeled flow
(25 percent Q2). Flow geometry in the upstream
transition (D) remains mostly within the range
of corresponding profile segments (E and H) at
all flows. The downstream transition segment
(A) exhibits greater depths and lower wetted
perimeter than corresponding profile segments
(G, H, and J).
Shear stress – Shear stress in the culvert and
in the upstream transition segment (D) spikes
to higher values than in corresponding profile
segments (figures 10 and 19). Shear stress in the
downstream transition (A) has a wider range than
that found in corresponding profile segments (G,
H, and J).
Excess shear – Modeling suggests that excess
shear in the culvert is mostly within the range
(or slightly lower) than the excess shear in the
natural channel (figure 20).
Pine Creek
Site Evaluations
Velocity – Velocity in the culvert and in the
upstream transition segment (D) spikes to higher
values than in corresponding profile segments
(figures 11 and 18). Velocity in the downstream
transition (A) has a wider range than that found in
corresponding profile segments (G, H, and J).
Scour summary
Originally placed material scoured out of the
pipe after construction. There is currently scour
to the culvert base at the upstream end (inlet) of
the culvert. There has been aggradation in the
downstream portion of the culvert. The bed has
therefore adjusted to a flatter slope than what
was originally constructed (assuming the original
culvert bed was constructed at the same gradient
as the structure). Hydraulic modeling indicates
high shear stress and velocity within the culvert,
indicating potential risk of continued scour during
high flow events.
The culvert appears to have most likely been
placed lower in the profile than the original
stream. This could relate to channel adjustments
from the previous culvert or may also be a
result of restrictions in height imposed by the
current road prism. The change in profile has
caused upstream incision. Deposition of coarse
material upstream of the culvert may be due
to culvert backwater during a high flood event
(possible debris plugging). Subsequent lateral
boundary adjustment has occurred in response
to this deposited material and has resulted in the
lateral migration of the channel in the right bank
direction. This has altered the culvert alignment,
creating a sharp bend at the inlet that contributes
to inlet scour.
Pine Creek
AOP Conditions
Cross-section complexity – The sum of squared
height differences in the culvert cross sections
are both within the range of those in the channel
cross sections (table 3).
Profile complexity – Vertical sinuosity in the
culvert and transition segments are within the
range of those in the channel segments (table 4).
Depth distribution – The upstream culvert cross
section (riffle) has a depth-distribution value
within the range of channel conditions but the
downstream culvert cross section (glide) has a
value less than channel conditions (table 5).
Habitat units – The culvert has more glide habitat
and less pool and riffle habitat than the natural
channel (table 6).
Residual depths – The upstream culvert segment
(C) residual depth is greater than any residual
depth found in the natural channel (figure 21).
This is the location of inlet scour. Residual
depth in the downstream portion of the culvert
(B) is within the range of residual depths in
corresponding profile segments (G and J).
Residual depth in the downstream transition
segment (A) is within or above the range of
depths in corresponding profile segments in the
natural channel (G, H, and J). Residual depth
in the upstream transition segment (D) is within
the range of depths in corresponding profile
segments in the natural channel (E and H).
Substrate – The bed-material distribution in the
riffle in the culvert is similar to the bed material
in the step in representative channel reach one
(downstream) but coarser than the riffles in
representative channel reach two (upstream). The
bed-material distribution in the glide in the culvert
is similar to the glide in representative channel
reach one. Culvert bed material sorting values
diverge only slightly from the range of values
found in the natural channel (table 7). Pebble
count data is provided at the end of this summary.
A—363
Culvert Scour Assessment
Large woody debris – There was no LWD present
in the culvert (table 8). The representative
channel had moderate LWD abundance. LWD
formed steps and scour pools in the channel
outside the crossing and played a primary role in
habitat unit creation and complexity. Features in
the culvert did not mimic the role of wood in the
natural channel.
AOP summary
Site observations and complexity measures
indicate that this site is moderately suitable for
AOP. There is flow concentration that would allow
for passage during low flows and there is some
coarse material that would create velocity refuge
at higher flows. The high velocity spikes indicated
in the hydraulic modeling could potentially limit
fish passage at high flows. The thalweg runs
along the culvert edge for much of the length,
limiting the roughness and associated velocity
refuge that is found in the natural channel outside
the crossing. There is an exposed bank on the
A—364
left bank of the culvert for terrestrial organism
passage, but no bank exists along most of the
right bank.
Design Considerations
Inlet scour, upstream incision, and upstream
lateral boundary adjustment could likely have
been reduced by raising the invert elevation
of the culvert bed; however, this may have
required raising the elevation of the road prism at
considerable expense. Adding stable, embedded
boulders into the culvert bed would reduce risk
of scour to the culvert base, which is currently
occurring. Use of an open-bottom arch at this
location would allow for the construction of stable
bed elements while not significantly reducing
culvert capacity. Creation of continuous banks
along both culvert walls would reduce the smooth
wall-based flow currently occurring along much
of the length and would also benefit terrestrial
organism passage.
Pine Creek
Pine Creek
500
S egment
L ength (ft)
43
52
18
50
93
19
70
21
14
16
XS 7
D
D
A
A
A
G
H
J
E
H
G
J
B
B
U ps trea m T ra n s itio n
D
XS 8
25.7%
25.4%
15.4%
3.6%
21.2%
12.6%
0.6%
% D ifferen c e in
G ra d ien t
XS 9
(s te p )
P ebble c ount
XS 1 0 :
D is ta n c e a lo n g b e d (fe e t)
300
(ri ffl e )
P ebble c ount
XS 5 :
XS 6
C
R epres en ta tiv e
C h a n n el S eg men t
(p o o l /g l i d e )
P ebble c ount
XS 4 :
B
C u lv e rt
C u lv ert S eg men t
XS 2
XS 3
D o w n s trea m T ra n s itio n
Table 1­—Segment comparisons
400
XS 1
A
S egment G radient
0.045
0.038
0.022
0.077
0.074
0.223
0.034
0.061
0.014
0.038
Figure 2—Pine Creek longitudinal profile.
90
95
100
Relative elevation (feet)
105
110
115
120
125
130
S egment
A
B
C
D
E
F
G
H
I
J
E
XS 1 1 :
200
(g l i d e )
P ebble c ount
fo rm i n g s te p
w ood jam
XS 1 2
F
(ri ffl e )
P ebble c ount
XS 1 4 :
100
R e p re s e n ta ti ve C h a n n e l
XS 1 3
G
XS 1 5 :
(ri ffl e )
P ebble c ount
H
I
J
XS 1 6
0
Site Evaluations
A—365
n
o
i
t
a
v
e
l
E
)
t
f
(
A—366
B
D
E
G
H
J
0.1102 – 0.1107
0.1099 – 0.1117
0.1117 – 0.1147
0.1527 – 0.1578
0.1527
0.0987 – 0.1284
0.1273 – 0.1321
1
1
2
4
2
2
3
# of measured XSs
2
3
7
9
7
7
6
# of interpolated XSs
95
100
105
110
115
120
125
0
*
2 6
. .
1 1 2
*
5
.
2
5
7 8
. .
3 3 3
Figure 3—HEC-RAS profile.
1
5
.
4
*
6
6
6
6
4 7
. .
7 7
*
3
3
3
3
2
.
8
*
6
6
6
6
4 7
. .
8 8
9
*
3
3
3
3
3
.
9
0
1
6
.
0
1
*
5
1
.
1
1
200
*
3 4
. .
1 1
1 1
*
5
7
.
1
1
Main Channel Dis tance (ft)
*
6
6
6
6
6
.
9
2
1
3
.
2
1
5
.
2
1
*
5
7
.
2
1
3
1
*
3
3
3
3
.
3
1
*
6
6
6
6
.
3
1
4
1
300
*
2
.
4
1
*
4
.
4
1
Stations with decimal values are interpolated cross sections placed along the surveyed profile.
5
2
.
5
*
3
3
3
3
5
2
.
.
5 7 7
100
6
.
4
1
*
8
.
4
1
5
1
4
.
5
1
*
7
.
5
1
6
1
400
Ground
W S 15 c fs
W S Qbf
W S Q10
W S Q50
W S Q100
L e ge nd
Obtained using equation from Jarrett (1984): n = 0.39S0.38R-0.16, where S=stream slope; R=hydraulic radius. Jarrett’s equation only applied
within the following ranges: S = 0.002 to 0.08, R = 0.5 ft to 7 ft. For cross sections outside these ranges, n was computed either from adjacent
sections that fell within the ranges, using the guidance of Arcement and Schneider (1987), or from the HEC-RAS recommendations for culvert
modeling.
A
SegmentRange of Manning's n values1
Table 2—Summary of segments used for comparisons
Culvert Scour Assessment
Pine Creek
Pine Creek
Elevation (ft)
n
o
i
t
a
v
e
l
E
)
t
f
(
n
o
i
t
a
v
e
l
E
)
t
f
(
60
RS = 14
30
70
.1147
Station (ft)
20
80
40
90
.1147
50
60
W S Q1 0 0
L e ge n d
119
20
120
Station (ft)
100
B a n k S ta
L e ve e
G ro u n d
W S 1 5 c fs
W S Qb f
n
o
i
t
a
v
e
l
E
)
t
f
(
n
o
i
t
a
v
e
l
E
Elevation (ft)
118
119
120
122
121
123
124
126
125
120
-10
121
122
124
123
10
.1117
30
30
40
60
50
.1117
60
80
70
20
50
Station (ft)
40
.1117
RS = 13
Station (ft)
70
B a n k S ta
L e ve e
G ro u n d
W S 1 5 c fs
W S Qb f
W S Q1 0
W S Q5 0
W S Q1 0 0
L e ge n d
B a n k S ta
L e ve e
G ro u n d
W S 1 5 c fs
W S Qb f
W S Q1 0
20
L e ge n d
W S Q1 0 0
125
10
.1099
W S Q5 0
0
RS = 15
.1099
126
128
127
.1099
Figure 4—Cross-section plots. Only measured cross sections are included. Manning’s n values are included at the top of the cross section. The
stationing (RS) corresponds to the stationing on the HEC-RAS profile. Green arrows define the ineffective flow areas. Black arrows represent
points identified in the field as the bankfull channel boundary. Only those points identified in the field and supported by hydraulic and topographic
analyses are shown below.
Elevation (ft)
121
123
122
W S Q1 0
50
10
Bank St a
Ground
WS 15 c fs
WS Qbf
WS Q10
WS Q50
WS Q100
L e ge nd
W S Q5 0
40
.1147
0
.
1
1
0
7
124
30
-10
.1107
Elevation (ft)
125
127
126
121
-20
122
123
125
124
126
127
129
128
.1107
RS = 16
)
t
f
(
Site Evaluations
A—367
n
o
i
t
a
v
e
l
E
)
t
f
(
Elevation (ft)
n
o
i
t
a
v
e
l
E
)
t
f
(
A—368
0
10
30
50
60
70
80
20
30
40
50
60
70
80
W S Q1 0 0
L e ge n d
109
110
Station (ft)
B a n k S ta
L e ve e
G ro u n d
W S 1 5 c fs
W S Qb f
n
o
i
t
a
v
e
l
E
)
t
f
(
Elevation (ft)
106
-20
107
108
110
109
111
112
114
113
109
-20
110
111
113
112
114
115
117
116
-10
-10
0
0
10
.1527
10
.1551
Station (ft)
20
30
30
.1527
RS = 9
Station (ft)
20
.1551
RS = 11
.
1
5
2
7
.
1
5
5
1
40
40
50
50
60
60
L e ge nd
Bank St a
Ground
WS 15 c fs
WS Qbf
WS Q10
WS Q50
WS Q100
L e ge nd
Bank St a
Ground
WS 15 c fs
WS Qbf
WS Q10
WS Q50
WS Q100
Figure 4—Cross-section plots. Only measured cross sections are included. Manning’s n values are included at the top of the cross section. The
stationing (RS) corresponds to the stationing on the HEC-RAS profile. Green arrows define the ineffective flow areas. Black arrows represent
points identified in the field as the bankfull channel boundary. Only those points identified in the field and supported by hydraulic and topographic
analyses are shown below. (continued)
Elevation (ft)
111
113
112
W S Q1 0
10
.1527
114
.1527
RS = 10
Station (ft)
40
B a n k S ta
L e ve e
G ro u n d
W S Q5 0
0
.1527
20
W S Qb f
W S 1 5 c fs
n
o
i
t
a
v
e
l
E
Elevation (ft)
115
117
116
112
113
114
116
115
W S Q1 0
W S Q1 0 0
L e ge n d
117
.1557
W S Q5 0
.1557
118
120
119
.1557
RS = 12
)
t
f
(
Culvert Scour Assessment
Pine Creek
)
t
f
(
Pine Creek
Elevation (ft)
n
o
i
t
a
v
e
l
E
)
t
f
(
n
o
i
t
a
v
e
l
E
20
30
RS = 6
50
50
60
60
70
W S Q1 0 0
L e ge n d
70
101
-10
102
103
Station (ft)
In e ff
B a n k S ta
Elevation (ft)
-20
-10
30
40
50
50
60
L e ge n d
W S Q1 0 0
101
-30
102
103
104
105
106
107
108
109
102
-10
103
104
106
105
0
Station (ft)
10
.1124
20
RS = 5
Note: n values for first profile.
Station (ft)
30
40
Bank St a
Ground
WS 15 c fs
WS Qbf
WS Q10
WS Q50
WS Q100
L e ge nd
B a n k S ta
In e ff
G ro u n d
W S 1 5 c fs
W S Qb f
W S Q1 0
20
.1527
W S Q5 0
10
.1527
107
0
.1527
108
110
109
RS = 7
Figure 4—Cross-section plots. Only measured cross sections are included. Manning’s n values are included at the top of the cross section. The
stationing (RS) corresponds to the stationing on the HEC-RAS profile. Green arrows define the ineffective flow areas. Black arrows represent
points identified in the field as the bankfull channel boundary. Only those points identified in the field and supported by hydraulic and topographic
analyses are shown below. (continued)
Elevation (ft)
G ro u n d
W S 1 5 c fs
W S Qb f
n
o
i
t
a
v
e
l
E
)
t
f
(
Elevation (ft)
105
104
40
.1527
40
106
10
30
Station (ft)
.1527
20
B a n k S ta
L e ve e
G ro u n d
n
o
L e ge n d
i
W S Q1 0 0 t
a
W S Q5 0
v
W S Q1 0
e
W S Qb f l
E
W S 1 5 c fs
W S Q1 0
.1527
10
.1527
W S Q5 0
0
0
.1527
107
109
108
104
-10
105
106
108
107
109
110
112
111
.1527
RS = 8
)
t
f
(
Site Evaluations
A—369
n
o
i
t
a
v
e
l
E
)
t
f
(
Elevation (ft)
n
o
i
t
a
v
e
l
E
)
t
f
(
A—370
99
-10
100
0
10
.1321
-10
0
20
30
20
Station (ft)
.1321
RS = 2
Station (ft)
10
40
.
1
3
2
1
30
50
40
60
50
70
B a n k S ta
In e ff
L e ve e
G ro u n d
n
o
L e ge n d
i
W S Q1 0 t0
W S Q5 0a
v
W S Q1 0
e
W S Qb f
l
W S 1 5 c fs
E
)
t
f
(
Elevation (ft)
.1273
30
40
50
60
70
L e ge n d
W S Q1 0 0
97
-10
98
99
101
100
102
103
105
104
99
-10
100
101
103
102
0
10
20
30
40
.1273
Station (ft)
.1273
RS = 1
Station (ft)
50
60
70
B a n k S ta
L e ve e
G ro u n d
W S 1 5 c fs
W S Qb f
W S Q1 0
W S Q5 0
W S Q1 0 0
L e ge n d
B a n k S ta
In e ff
G ro u n d
W S 1 5 c fs
W S Qb f
W S Q1 0
20
.13
W S Q5 0
10
RS = 3
104
0
.13
105
107
106
.13
Figure 4—Cross-section plots. Only measured cross sections are included. Manning’s n values are included at the top of the cross section. The
stationing (RS) corresponds to the stationing on the HEC-RAS profile. Green arrows define the ineffective flow areas. Black arrows represent
points identified in the field as the bankfull channel boundary. Only those points identified in the field and supported by hydraulic and topographic
analyses are shown below. (continued)
Elevation (ft)
101
103
102
-20
Bank St a
Ground
WS 15 c fs
WS Qbf
WS Q10
WS Q50
WS Q100
L e ge nd
n
o
i
t
a
v
e
l
E
Elevation (ft)
104
105
107
106
99
-30
100
101
102
103
104
105
106
107
.0987
RS = 4
Note: n values for first profile.
)
t
f
(
Culvert Scour Assessment
Pine Creek
Pine Creek
.
P
.
W
l
a
t
o
T
0
10
20
30
40
50
60
70
80
0
A
Culvert
B
100
C
W.P. total (ft)
0
A
Culvert
B
Figure 6—Wetted perimeter.
0
10
20
30
40
50
60
100
C
Figure 5—Flow area (total) profile plot.
Flow area (sq ft)
)
t
f
(
w
o
l
F
a
e
r
A
q
s
(
)
t
f
D
D
Main Channel Distance (ft)
200
E
Main Channel Distance (ft)
200
E
F
F
300
G
300
G
Flow
H I
Flow
H I
J
J
400
400
W.P. Total 15 cfs
W.P. Total Qbf
W.P. Total Q10
W.P. Total Q50
W.P. Total Q100
Legend
Flow Area 15 cfs
Flow Area Qbf
Flow Area Q10
Flow Area Q50
Flow Area Q100
Legend
Site Evaluations
A—371
A—372
p
o
T
h
t
d
i
W
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0
A
Culvert
B
0
10
0
A
Figure 8—Top width.
Top width (ft)
20
30
40
50
60
Culvert
B
Figure 7—Hydraulic radius.
Hydraulic radius (ft)
)
t
f
(
r
d
y
H
s
u
i
d
a
R
)
t
f
(
100
C
100
C
D
D
Main Channel Distance (ft)
200
E
Main Channel Distance (ft)
200
E
F
F
300
G
300
G
Flow
H I
Flow
H I
J
J
400
400
Top Width 15 cfs
Top Width Qbf
Top Width Q10
Top Width Q50
Top Width Q100
Legend
Hydr Radius 15 cfs
Hydr Radius Qbf
Hydr Radius Q10
Hydr Radius Q50
Hydr Radius Q100
Legend
Culvert Scour Assessment
Pine Creek
r
a
e
h
S
n
a
h
C
0
1
2
3
4
5
0
A
Culvert
B
Pine Creek
Shear channel (lbs/sq ft)
A—373
0
A
Culvert
B
100
C
100
C
Figure 10—Shear stress (channel) profile.
0
5
10
15
20
Figure 9—Maximum depth.
Maximum channel depth (ft)
q
s
/
b
l
(
)
t
f
x
a
M
l
h
C
h
t
p
D
)
t
f
(
D
D
Main Channel Distance (ft)
200
E
Main Channel Distance (ft)
200
E
F
F
300
G
300
G
Flow
H I
Flow
H I
J
J
400
400
Shear Chan 15 cfs
Shear Chan Qbf
Shear Chan Q10
Shear Chan Q50
Shear Chan Q100
Legend
Max Chl Dpth 15 cfs
Max Chl Dpth Qbf
Max Chl Dpth Q10
Max Chl Dpth Q50
Max Chl Dpth Q100
Legend
Site Evaluations
)
s
/
t
f
(
A—374
l
e
V
l
n
h
C
0
0
A
Culvert
B
100
C
Figure 11—Velocity (channel) profile plot.
Velocity channel (ft/s)
1
2
3
4
5
6
7
8
D
Main Channel Distance (ft)
200
E
F
300
G
Flow
H I
J
400
Vel Chnl 15 cfs
Vel Chnl Qbf
Vel Chnl Q10
Vel Chnl Q50
Vel Chnl Q100
Legend
Culvert Scour Assessment
Pine Creek
40
60
80
B (culv)
G
G
E
D (US Trans)
25%Q2
A (ds trans)
D (us trans)
E
H
H
Figure 12—Flow area (total).
0
A (DS Trans)
J
G
G
E
D (US Trans)
B (Culv)
A (DS Trans)
Qbf
A (ds trans)
D (us trans)
B (culv)
E
H
J
100%
of the
values
50%
of the
values
E
E
D (US Trans)
B (Culv)
G
A (DS Trans)
10
A (ds trans)
D (us trans)
B (culv)
G
H
J
A (DS Trans)
H
J
E
D (US Trans)
G
G
B (Culv)
50
A (ds trans)
D (us trans)
B (culv)
E
Minimum value
25th percentile
H
J
J
H
Median (aka 50th percentile)
75th percentile
Maximum value
Box Plot Explanation
E
D (US Trans)
B (Culv)
B (culv)
E
G
G
100
A (ds trans)
D (us trans)
A (DS Trans)
Pine Creek
Flow
20Area (ft2)
Flow area (ft2)
B (Culv)
H
J
Site Evaluations
A—375
J
H
J
H
J
G
D (US Trans)
B (culv)
G
25%Q2
A (ds trans)
D (us trans)
E
Figure 14—Hydraulic radius.
0
0.5 Radius (ft)
Hydraulic
1
1.5
2
2.5
3
E
Figure 13—Wetted perimeter.
G
J
H
J
G
Qbf
B (culv)
G
Qbf
H
H
H
A (ds trans)
D (us trans)
E
A (ds trans)
D (us trans)
B (culv)
E
J
J
J
J
H
J
E
25%Q2
J
A (DS Trans)
A (DS Trans)
A (ds trans)
D (us trans)
H
H
B (Culv)
B (Culv)
B (culv)
H
D (US Trans)
D (US Trans)
G
B (culv)
E
G
10
E
B (culv)
10
A (ds trans)
D (us trans)
G
A (ds trans)
D (us trans)
A (DS Trans)
A (DS Trans)
E
E
B (Culv)
B (Culv)
E
D (US Trans)
D (US Trans)
G
G
E
E
0
H
H
H
H
20
J
J
J
J
30
G
E
G
50
A (ds trans)
D (us trans)
B (culv)
50
A (ds trans)
D (us trans)
B (culv)
E
H
H
H
H
40
J
J
J
J
50
A (DS Trans)
A (DS Trans)
G
G
B (Culv)
B (Culv)
A (DS Trans)
A (DS Trans)
B (culv)
E
G
B (culv)
G
100
A (ds trans)
D (us trans)
E
100
A (ds trans)
D (us trans)
A (DS Trans)
A (DS Trans)
B (Culv)
B (Culv)
D (US Trans)
D (US Trans)
B (Culv)
B (Culv)
Wetted
10 Perimeter (ft)
Hydraulic radius (ft)
D (US Trans)
D (US Trans)
D (US Trans)
E
E
E
E
G
G
G
G
A—376
H
H
H
H
Wetted perimeter (ft)
J
J
J
J
60
Culvert Scour Assessment
Pine Creek
Maximum depth (ft)
D (US Trans)
A—377
G
25%Q2
A (ds trans)
D (us trans)
B (culv)
E
Figure 16—Maximum depth.
0
1
Maximum
Depth (ft)
2
3
4
5
G
G
H
J
E
G
G
Qbf
A (ds trans)
D (us trans)
B (culv)
E
Qbf
A (ds trans)
D (us trans)
B (Culv)
E
E
Figure 15—Top width.
H
H
B (Culv)
B (culv)
D (US Trans)
D (US Trans)
25%Q2
J
J
E
E
A (ds trans)
D (us trans)
J
A (DS Trans)
A (DS Trans)
G
G
B (culv)
H
H
H
H
H
J
J
E
G
G
10
A (ds trans)
D (us trans)
B (culv)
E
10
A (ds trans)
D (us trans)
B (culv)
B (Culv)
B (Culv)
G
D (US Trans)
D (US Trans)
E
J
J
E
E
0
A (DS Trans)
A (DS Trans)
G
G
10
H
H
H
H
J
J
E
G
G
50
A (ds trans)
D (us trans)
B (culv)
E
50
A (ds trans)
D (us trans)
B (culv)
B (Culv)
B (Culv)
20
D (US Trans)
D (US Trans)
Top Width (ft)
J
J
E
E
30
H
H
J
J
J
J
40
A (DS Trans)
A (DS Trans)
G
G
E
G
G
100
A (ds trans)
D (us trans)
B (culv)
E
100
A (ds trans)
D (us trans)
B (culv)
B (Culv)
B (Culv)
50
D (US Trans)
D (US Trans)
60
H
H
E
E
A (DS Trans)
A (DS Trans)
A (DS Trans)
A (DS Trans)
G
G
B (Culv)
B (Culv)
H
H
H
H
Pine Creek
J
J
J
J
Top width(ft)
D (US Trans)
Site Evaluations
B (Culv)
D (US Trans)
E
G
25%Q2
A (ds trans)
D (us trans)
B (culv)
D (US Trans)
H
J
G
B (culv)
G
Qbf
A (ds trans)
D (us trans)
E
Qbf
H
H
J
J
J
J
E
E
Figure 18—Velocity (channel).
0
Velocity
2 (ft/sec)
4
6
8
G
Figure 17—Width-to-depth ratio.
H
H
A (ds trans)
D (us trans)
B (Culv)
G
25%Q2
J
J
B (Culv)
B (culv)
D (US Trans)
D (US Trans)
B (culv)
A (DS Trans)
A (DS Trans)
G
G
B (culv)
E
G
B (culv)
G
10
A (ds trans)
D (us trans)
E
10
A (ds trans)
D (us trans)
B (Culv)
B (Culv)
E
D (US Trans)
D (US Trans)
A (ds trans)
D (us trans)
J
H
H
J
J
J
J
E
E
H
H
H
E
E
G
A (DS Trans)
A (DS Trans)
G
G
B (culv)
E
G
B (culv)
G
50
A (ds trans)
D (us trans)
E
50
A (ds trans)
D (us trans)
B (Culv)
B (Culv)
E
D (US Trans)
D (US Trans)
0
H
H
E
E
20
H
H
J
J
J
J
40
A (DS Trans)
A (DS Trans)
G
G
B (culv)
E
G
B (culv)
G
100
A (ds trans)
D (us trans)
E
100
A (ds trans)
D (us trans)
B (Culv)
B (Culv)
60
D (US Trans)
D (US Trans)
A (DS Trans)
A (DS Trans)
H
H
E
E
Width-to-depth Ratio
Velocity (ft/sec)
B (Culv)
A (DS Trans)
A (DS Trans)
G
G
A—378
H
H
H
H
Width-to-depth ratio
J
J
J
J
80
Culvert Scour Assessment
Pine Creek
E
G
G
25%Q2
A (ds trans)
D (us trans)
B (culv)
E
H
J
Excess shear (Applied/tcrit)
0
50
J
H
100
Dis charge (cfs )
G
D (US Trans)
150
Qbf
H
200
H
E
D (US Trans)
B (Culv)
G
G
A (DS Trans)
10
A (ds trans)
D (us trans)
B (culv)
E
J
Culvert (DS pebble count) - pool/glide
Culvert (US pebble count) - riffle
US Channel (DS pebble count) - step
US Channel (DS Mid pebble count) - glide
US Channel (US Mid pebble count) - riffle
H
H
US Channel (US pebble count) - riffle
J
J
D (US Trans)
B (Culv)
Figure 20—Excess shear stress.
G
G
A (DS Trans)
50
A (ds trans)
D (us trans)
B (culv)
E
E
J
B (Culv)
Excess shear stress is the channel shear divided by the critical shear for bed entrainment of the D84
particle size. Values of excess shear greater than 1 indicate bed movement for the D84 particle size.
0
2
Excess Shear (Applied / tcrit)
4
6
8
10
12
14
E
B (culv)
E
G
A (ds trans)
D (us trans)
A (DS Trans)
Figure 19—Shear stress (channel).
0
A (DS Trans)
Shear Stress (lbs/ft2)
5
10
15
B (Culv)
Shear stress (lbs/ft2)
D (US Trans)
Pine Creek
20
25
H
J
E
D (US Trans)
B (Culv)
G
G
A (DS Trans)
100
A (ds trans)
D (us trans)
B (culv)
E
H
J
Site Evaluations
A—379
J
H
J
H
Culvert Scour Assessment
Table 3—Sum of squared height difference
Reach
XSUnit
Location
type
Culvert
Sum of squared
height difference Within range of channel conditions?
US
Riffle
0.03
Yes
DS
Pool/glide
0.03
Yes
US
Riffle
0.02
DS
Riffle
0.02
Upstream (1-DS)
US
Glide
0.08
DS
Step
0.04
Upstream (2-US)
Table 4—Vertical sinuosity
Segment
LocationVertical Sinuosity (ft/ft)
A
DS transition
1.008
B
Culvert
1.003
C
Culvert
1.013
D
US transition
1.010
E
US channel
1.009
F
US channel
1.059
G
US channel
1.003
H
US channel
1.018
I
US channel
1.011
J
US channel
1.005
Table 5—Depth distribution
Reach
Culvert
XS
25% Q2
Location
Within range of
channel conditions?
US
6
Yes
DS
0
No
US
23
DS
18
US
1
DS
2
Upstream (2-US)
Upstream (1-DS)
A—380
Pine Creek
Site Evaluations
Table 6—Habitat unit composition
Percent of surface area
Reach
Pool Glide
Riffle
Step
Culvert
22%
41%
38%
0%
Upstream Channel (2-US)
36%
0%
63%
1%
Upstream Channel (1-DS)
49%
0%
46%
4%
1.2

1.0
0.8



0.6
0.4
Residual depth (ft)



0.2





Segment J
Segment i
Segment H
Segment G
Segment F
Segment E
Segment D:
US Trans
Segment C:
Culvert

Segment B:
Culvert
Segment A:
DS Trans
0.0



DS
US
Culvert
Culvert
Transition
Transition
Segment F Segment GSegment HSegment I Segment J
Segment A: Segment B:Segment Segment
C:
D: Segment E
Figure 21—Residual depths.
Table 7—Bed material sorting and skewness
Reach
XSUnit
Sorting
Location
Type
Culvert
Within range Skewness Within range
of channel
of channel
conditions?
conditions?
US
Riffle
1.57
No
0.33
Yes
DS
Pool/glide
2.02
No
0.18
Yes
US
Riffle
1.81
0.03
DS
Riffle
1.92
-0.08
US
Glide
2.01
-0.10
DS
Step
1.92
0.49
Upstream (2-US)
Upstream (1-DS)
Pine Creek
A—381
Culvert Scour Assessment
Table 8. Large woody debris
Reach
Pieces/Channel Width
Culvert
0
Upstream (2-US)
1.34
Upstream (1-DS)
1.17
Terminology:
US = Upstream
DS = Downstream
RR = Reference reach
XS = Cross section
A—382
Pine Creek
Site Evaluations
View upstream through culvert.
View downstream towards culvert inlet.
View downstream from roadway.
View upstream from roadway.
Upstream reference reach 2 (upstream).
Upstream reference reach 2 (upstream) – downstream pebble count (riffle).
Pine Creek
A—383
Culvert Scour Assessment
Upstream reference reach 2 (upstream) – View of upstream reference reach 1 (downstream).
downstream pebble count (pool tail-out).
Upstream reference reach 1 (downstream) – Upstream reference reach 1 (downstream) –
downstream pebble count (step).
upstream pebble count (between steps).
View downstream towards inlet.
View upstream from within culvert.
A—384
Pine Creek
Site Evaluations
Material
Frequency
sand
very fine gravel
fine gravel
fine gravel
medium gravel
medium gravel
coarse gravel
coarse gravel
very coarse gravel
very coarse gravel
small cobble
medium cobble
large cobble
very large cobble
small boulder
small boulder
medium boulder
large boulder
very large boulder
bedrock
S ize C las s (mm)
<2
2-4
4 - 5.7
5.7 - 8
8 - 11.3
11.3 - 16
16 - 22.6
22.6 - 32
32 - 45
45 - 64
64 - 90
90 - 128
128 - 180
180 - 256
256 - 362
362 - 512
512 - 1024
1024 - 2048
2048 - 4096
Bedrock
C ount
Item %
C umulative %
4
4
3
6
8
11
12
8
6
6
10
9
19
5
3
0
0
0
0
0
4%
4%
3%
5%
7%
10%
11%
7%
5%
5%
9%
8%
17%
4%
3%
0%
0%
0%
0%
0%
4%
7%
10%
15%
22%
32%
42%
49%
54%
60%
68%
76%
93%
97%
100%
100%
100%
100%
100%
100%
20
100%
18
90%
16
80%
14
70%
12
60%
10
50%
8
Frequency
40%
6
30%
4
20%
2
10%
Cumulative Frequency
Bedrock
2048-4096
1024-2048
362-512
512-1024
256-362
180-256
128-180
64-90
90-128
45-64
32-45
22.6-32
11.3-16
16-22.6
5.7-8
8-11.3
2-4
<2
4-5.7
0%
<2
0
Cumulative Frequency
Cross Section: Upstream Reference Reach 2 – Upstream Pebble Count
2-4
4 - 5.7 - 8
32 -45
45-64
64- 90
8 - 11.3
90 - 128
Bedrock
11.3
16- 16
-22.6
22.6- 32
128180
- 180
256
- 256
362
- 362
- 512
512 - 1024
Particle Size Category (mm)
1024
2048
- 2048
- 4096
Partic le Siz e Category (mm)
S ize C las s
S ize perc ent finer
than (mm)
D5
D16
D50
D84
D95
D100
3.65
10
34
139.6
190
290
Pine Creek
Material
P erc ent C ompos ition
Sand
Gravel
Cobble
Boulder
Bedrock
4%
56%
38%
3%
0%
Sorting Coefficient:
1.81
Skewness Coefficient: 0.03
A—385
Culvert Scour Assessment
Cross Section: Upstream Reference Reach 2 – Downstream Pebble Count
Material
S ize C las s (mm)
sand
very fine gravel
fine gravel
fine gravel
medium gravel
medium gravel
coarse gravel
coarse gravel
very coarse gravel
very coarse gravel
small cobble
medium cobble
large cobble
very large cobble
small boulder
small boulder
medium boulder
large boulder
very large boulder
bedrock
C ount
Item %
C umulative %
5
6
1
7
7
11
9
15
9
8
4
6
13
6
0
0
0
0
0
0
5%
6%
1%
7%
7%
10%
8%
14%
8%
7%
4%
6%
12%
6%
0%
0%
0%
0%
0%
0%
5%
10%
11%
18%
24%
35%
43%
57%
65%
73%
77%
82%
94%
100%
100%
100%
100%
100%
100%
100%
<2
2-4
4 - 5.7
5.7 - 8
8 - 11.3
11.3 - 16
16 - 22.6
22.6 - 32
32 - 45
45 - 64
64 - 90
90 - 128
128 - 180
180 - 256
256 - 362
362 - 512
512 - 1024
1024 - 2048
2048 - 4096
Bedrock
16
100%
14
90%
70%
Frequency
10
60%
50%
8
40%
Frequency
6
30%
4
20%
2
Cumulative Frequency
80%
12
Cumulative Frequency
10%
Bedrock
2048-4096
1024-2048
362-512
512-1024
256-362
180-256
128-180
64-90
90-128
45-64
32-45
22.6-32
11.3-16
16-22.6
5.7-8
8-11.3
2-4
<2
4-5.7
0%
<2
0
2-4
4 - 5.7 - 8
32 -45
45-64
64- 90
8 - 11.3
90 - 128
Bedrock
11.316- 16
-22.6
22.6- 32
128180
- 180
256
- 256
362
- 362
- 512
512 - 1024
Particle Size Category (mm)
1024
2048
- 2048
- 4096
Particle Size Category (mm)
S ize C las s
S ize perc ent finer
than (mm)
D5
D16
D50
D84
D95
D100
3
8
25
130
194
250
A—386
Material
P erc ent C ompos ition
Sand
Gravel
Cobble
Boulder
Bedrock
5%
68%
27%
0%
0%
Sorting Coefficient:
1.92
Skewness Coefficient:-0.08
Pine Creek
Site Evaluations
Material
sand
very fine gravel
fine gravel
fine gravel
medium gravel
medium gravel
coarse gravel
coarse gravel
very coarse gravel
very coarse gravel
small cobble
medium cobble
large cobble
very large cobble
small boulder
small boulder
medium boulder
large boulder
very large boulder
bedrock
S ize C las s (mm)
C ount
Item %
C umulative %
6
6
2
1
5
16
9
11
9
8
8
4
10
7
5
2
0
0
0
0
6%
6%
2%
1%
5%
15%
8%
10%
8%
7%
7%
4%
9%
6%
5%
2%
0%
0%
0%
0%
6%
11%
13%
14%
18%
33%
41%
51%
60%
67%
74%
78%
87%
94%
98%
100%
100%
100%
100%
100%
<2
2-4
4 - 5.7
5.7 - 8
8 - 11.3
11.3 - 16
16 - 22.6
22.6 - 32
32 - 45
45 - 64
64 - 90
90 - 128
128 - 180
180 - 256
256 - 362
362 - 512
512 - 1024
1024 - 2048
2048 - 4096
Bedrock
18
100%
16
90%
14
80%
70%
Frequency
12
60%
10
50%
8
Frequency
6
40%
30%
4
20%
2
10%
Bedrock
2048-4096
1024-2048
362-512
512-1024
256-362
180-256
90-128
128-180
64-90
45-64
32-45
22.6-32
11.3-16
16-22.6
5.7-8
8-11.3
4-5.7
<2
<2
2-4
4 - 5.7 - 8
32 -45
45-64
64- 90
8 - 11.3
90 - 128
Bedrock
11.316- 16
-22.6
22.6- 32
128180
- 180
256
- 256
362
- 362
- 512
512 - 1024
Particle Size Category (mm)
1024
2048
- 2048
- 4096
Particle Size Category (mm)
S ize C las s
S ize perc ent finer
than (mm)
D5
D16
D50
D84
D95
D100
2
11
30
160
286
450
Pine Creek
Cumulative Frequency
0%
2-4
0
Cumulative Frequency
Cross Section: Upstream Reference Reach 1 – Upstream Pebble Count
Material
P erc ent C ompos ition
Sand
Gravel
Cobble
Boulder
Bedrock
6%
61%
27%
6%
0%
Sorting Coefficient:
2.01
Skewness Coefficient:-0.10
A—387
Culvert Scour Assessment
Cross Section: Upstream Reference Reach 1 – Downstream Pebble Count
Material
sand
very fine gravel
fine gravel
fine gravel
medium gravel
medium gravel
coarse gravel
coarse gravel
very coarse gravel
very coarse gravel
small cobble
medium cobble
large cobble
very large cobble
small boulder
small boulder
medium boulder
large boulder
very large boulder
bedrock
S ize C las s (mm)
<2
2-4
4 - 5.7
5.7 - 8
8 - 11.3
11.3 - 16
16 - 22.6
22.6 - 32
32 - 45
45 - 64
64 - 90
90 - 128
128 - 180
180 - 256
256 - 362
362 - 512
512 - 1024
1024 - 2048
2048 - 4096
Bedrock
C ount
Item %
C umulative %
3
3
2
0
2
2
3
3
5
8
6
7
11
12
26
11
8
0
0
0
3%
3%
2%
0%
2%
2%
3%
3%
4%
7%
5%
6%
10%
11%
23%
10%
7%
0%
0%
0%
3%
5%
7%
7%
9%
11%
13%
16%
21%
28%
33%
39%
49%
60%
83%
93%
100%
100%
100%
100%
100%
30
90%
25
70%
20
Frequency
60%
50%
15
40%
Frequency
10
30%
20%
5
Cumulative Frequency
80%
Cumulative Frequency
10%
Bedrock
2048-4096
1024-2048
362-512
512-1024
256-362
180-256
128-180
64-90
90-128
45-64
32-45
22.6-32
11.3-16
16-22.6
5.7-8
8-11.3
2-4
<2
4-5.7
0%
<2
0
2-4
4 - 5.7
5.7 - 8
32 -45
45-64
64- 90
8 - 11.3
90 - 128
Bedrock
11.316- 16
-22.6
22.6- 32
128180
- 180
256
- 256
362
- 362
- 512
512 - 1024
Particle Size Category (mm)
1024
2048
- 2048
- 4096
Particle Size Category (mm)
S ize C las s
S ize perc ent finer
than (mm)
D5
D16
D50
D84
D95
D100
5
33.8
190
385
529
560
A—388
Material
P erc ent C ompos ition
Sand
Gravel
Cobble
Boulder
Bedrock
3%
25%
32%
40%
0%
Sorting Coefficient:
1.92
Skewness Coefficient: 0.49
Pine Creek
Site Evaluations
Cross Section: Culvert – Upstream Pebble Count
Material
sand
very fine gravel
fine gravel
fine gravel
medium gravel
medium gravel
coarse gravel
coarse gravel
very coarse gravel
very coarse gravel
small cobble
medium cobble
large cobble
very large cobble
small boulder
small boulder
medium boulder
large boulder
very large boulder
bedrock
S ize C las s (mm)
<2
2-4
4 - 5.7
5.7 - 8
8 - 11.3
11.3 - 16
16 - 22.6
22.6 - 32
32 - 45
45 - 64
64 - 90
90 - 128
128 - 180
180 - 256
256 - 362
362 - 512
512 - 1024
1024 - 2048
2048 - 4096
Bedrock
C ount
Item %
C umulative %
1
0
2
4
2
3
1
6
10
9
10
8
14
15
14
0
3
0
0
0
1%
0%
2%
4%
2%
3%
1%
6%
10%
9%
10%
8%
14%
15%
14%
0%
3%
0%
0%
0%
1%
1%
3%
7%
9%
12%
13%
19%
28%
37%
47%
55%
69%
83%
97%
97%
100%
100%
100%
100%
16
100%
14
90%
Frequency
70%
10
60%
8
50%
40%
Frequency
6
30%
4
20%
2
Cumulative Frequency
80%
12
Cumulative Frequency
10%
Bedrock
2048-4096
1024-2048
362-512
512-1024
256-362
180-256
128-180
64-90
90-128
45-64
32-45
22.6-32
11.3-16
16-22.6
5.7-8
8-11.3
2-4
<2
4-5.7
0%
<2
0
2-4
4 - 5.7 - 8
32 -45
45-64
64- 90
8 - 11.3
90 - 128
Bedrock
11.3
16- 16
-22.6
22.6- 32
128180
- 180
256
- 256
362
- 362
- 512
512 - 1024
Particle Size Category (mm)
1024
2048
- 2048
- 4096
Partic le Siz e Category (mm)
S ize C las s
S ize perc ent finer
than (mm)
D5
D16
D50
D84
D95
D100
8
30
110
258
300
540
Pine Creek
Material
P erc ent C ompos ition
Sand
Gravel
Cobble
Boulder
Bedrock
1%
36%
46%
17%
0%
Sorting Coefficient:
1.57
Skewness Coefficient: 0.33
A—389
Culvert Scour Assessment
Material
Frequency
sand
very fine gravel
fine gravel
fine gravel
medium gravel
medium gravel
coarse gravel
coarse gravel
very coarse gravel
very coarse gravel
small cobble
medium cobble
large cobble
very large cobble
small boulder
small boulder
medium boulder
large boulder
very large boulder
bedrock
S ize R ange (mm)
<2
2-4
4 - 5.7
5.7 - 8
8 - 11.3
11.3 - 16
16 - 22.6
22.6 - 32
32 - 45
45 - 64
64 - 90
90 - 128
128 - 180
180 - 256
256 - 362
362 - 512
512 - 1024
1024 - 2048
2048 - 4096
> 4096
C ount
Item %
C umulative %
6
10
1
5
7
12
7
12
4
18
7
6
5
3
0
1
0
0
0
0
6%
10%
1%
5%
7%
12%
7%
12%
4%
17%
7%
6%
5%
3%
0%
1%
0%
0%
0%
0%
6%
15%
16%
21%
28%
39%
46%
58%
62%
79%
86%
91%
96%
99%
99%
100%
100%
100%
100%
100%
20
100%
18
90%
16
80%
14
70%
12
60%
10
50%
8
Frequency
6
40%
30%
4
20%
2
10%
Cumulative Frequency
Bedrock
2048-4096
512-1024
1024-2048
362-512
256-362
180-256
128-180
64-90
90-128
45-64
32-45
22.6-32
16-22.6
8-11.3
11.3-16
5.7-8
<2
4-5.7
<2
0%
2-4
0
Cumulative Frequency
Cross Section: Culvert – Downstream Pebble Count
2-4
4 - 5.7
5.7 - 8
> 4096
32 -45
45-64
64- 90
8 - 11.3
90 - 128
11.316
- 16
-22.6
22.6- 32
128180
- 180
256
- 256
362
- 362
- 512
512 - 1024
Particle Size Category (mm)
1024
2048
- 2048
- 4096
Particle Size Category (mm)
S ize C las s
S ize perc ent finer
than (mm)
D5
D16
D50
D84
D95
D100
1
5
25
81
159
420
A—390
Material
P erc ent C ompos ition
Sand
Gravel
Cobble
Boulder
Bedrock
6%
73%
20%
1%
0%
Sorting Coefficient:
2.02
Skewness Coefficient: 0.18
Pine Creek