20081317 Ver 1_Appendix A entire_20160314

APPENDIX A
2015 (Year 5) Hydrogeomorphic Stream Surveys and Cross Section
Measurements by Michael Baker Engineering, Inc.

1.0 Geomorphic Monitoring
For monitoring stream restoration success criteria, 34 permanent cross-sections were installed
following construction in 2010 (Fig 1). In accordance with the Hell Swamp Mitigation Plan (July
2009), three cross-sections were established per 1,000 foot reach of stream/valley restoration.
The permanent cross-sections are used to monitor headwater valley formation and scour over
time. For the riparian headwater systems (no defined channel construction), these cross-
sections were measured for the as -built report and at Years 3 and 5 if channel features formed.
For the Scott Creek single thread channel stream restoration segment, two cross-sections were
measured for the as -built report and were surveyed annually during the monitoring period.
It was estimated that channel features may form naturally in unpredictable locations within the
project reaches over the 5 -year monitoring period. Therefore, in addition to the Scott Creek
annual cross-section surveys of cross-sections 7 and 8; 16 of the 34 original cross sections
were selected to resurvey in 2015. The selected cross-sections were based on proximity to
channel features noted by CZR during stream valley surveys which they conducted annually;
rarely did a cross section transect co-occur with a naturally formed feature.
1.1 Geomorphic Success Criteria
Valleys have been designed to remain stable with minimal changes through the
monitoring period; however, these cross-sections may show minor changes in flow
patterns as the headwater riparian valley systems develop.
1.1.1 Permanent Cross-sections 1 and 2
During Year 5 monitoring, cross-sections 1 and 2 were re -surveyed to record
changes within the Upper Scott Creek valley since as -built conditions. These cross-
sections were also re -surveyed during monitoring Year 3 based on observations by
field personnel. The Year 5 surveys were completed to document observations of
possible channel development and flow patterns. It is noted that these 2 cross-
sections are categorized as headwater valley cross-sections instead of riffle or pool
cross-sections. Graphs of these two monitored cross-sections are presented in this
report.
Cross-section 1 is the most upstream of the original cross sections of the Scott
Creek headwater valley. According to the Year 5 survey data, the thalweg has
remained very stable since as -built conditions and remains at the same elevation as
first surveyed. The ground elevations of the valley were also observed to be slightly
lower in elevation and the change is attributed to soil compaction and
microtopographic variability. Overall, cross-section 1 has remained stable and
exhibits elevations similar to those measured during the as -built survey.
Cross-section 2 is also located along the upstream section of the Scott Creek
headwater valley. According to the Year 5 survey data, the thalweg has remained
very stable since as -built conditions and the elevation remains fixed at 4.6 feet. The
ground elevations of the valley were observed to be slightly lower in elevation than
as built conditions. These observations are also attributed to soil compaction and
site maturity. Overall, cross-section 2 has also remained stable and exhibits
elevations similar to those found during as -built conditions.
Hell Swamp/Scott Creek Mitigation Site Appendix A - 1 PCS Phosphate Company, Inc.
Fifth Annual and Summary Report February 2016

1.1.2 Permanent Cross-sections 7 and 8
Two permanent cross-sections (7 and 8) were established in the Scott Creek single -
thread channel. Year 5 monitoring data from these permanent cross-sections were
collected in January 2015. Cross-sectional data collected during Year 5 monitoring
were compared to the as -built baseline data collected in 2010, Year 2 data collected
in 2011, Year 3 data collected in 2012 and Year 4 data collected in 2013. Cross-
sectional graphs for each of the annually monitored cross-sections are presented in
this report. In the presented cross-section graphs, the floodprone lines are widths
measured at an elevation twice the maximum bankfull depth of each individual
channel (e.g. cross-section 7 is a riffle feature and will have a lesser value than that
of the deep pool in cross-section 8, resulting in the differences between the 2
floodprone elevation lines).
Cross-section 7 is located across a riffle at station 47+66 on Scott Creek. It is noted
that this cross-section also transects the lower UT1 valley approximately at station
23+50. As shown in the cross-section 7 graph presented below, the UT1 thalweg is
on the right portion of the cross section.
According to the Year 5 survey data, the channel features in riffle cross-section 7
have remained mostly stable since as -built conditions. No significant areas of
concern regarding the channel within this cross-section were observed following
Year 5 monitoring. It is noted that the current bankfull depth (1.1 feet) is
approximately 0.4 foot lower in elevation than was measured following as -built
conditions (1.5 feet). This slight change is within expected natural variability of post -
constructed stream development and indicates that the riffle is stable and does not
currently show any movement toward channel instability.
The cross-section 7 survey data also illustrates channel development in the thalweg
area of UT1 following Year 5 monitoring. It is noted that the current UT1 thalweg
elevation (1.7 feet) is approximately 0.3 -foot lower in elevation than was measured
following as -built conditions (2.0 feet). This slight channel deepening in the thalweg
elevation was first noted during Year 4 monitoring. The 0.3 -foot change indicates
that the lower portion of UT1 is slowly developing a natural drainage pattern within
the area of cross-section 7. This cross-sectional area of UT1 appears stable and
does not currently show any movement toward channel instability.
Cross-section 8 is located across a pool feature at station 52+81 also on Scott
Creek. According to the Year 5 survey data, the channel features in pool cross-
section 8 have remained very stable since as -built conditions with some minor
deposition within the pool area of the channel. It is noted that the current bankfull
elevation (0.1 foot) is approximately 0.5 foot higher in elevation than as -built
conditions (-0.4 foot). Minor deposition is common for pools in restored meandering
channels and varies from year to year depending upon the flow frequency and
magnitude.
The changes observed following the Year 5 survey were found to be similar to the
as -built conditions data. This indicates that the floodplain in this area has
experienced very little adjustment since construction.
According to the Year 5 survey data, Scott Creek cross-sections 7 and 8
experienced minor adjustments and soil deposition throughout the 5 -year monitoring
period. The thalweg and floodplain changes observed along cross-sections 7 and 8
can be attributed to channel development, soil movement, vegetation maturity,
Hell Swamp/Scott Creek Mitigation Site Appendix A - 2 PCS Phosphate Company, Inc.
Fifth Annual and Summary Report February 2016

and/or slight differences in survey rod locations. These minor adjustments are to be
expected as the site matures and vegetation becomes established. Following the 5 -
year monitoring period, no areas of concern were observed within the Scott Creek
single -thread channel restoration segment.
During the Year 5 cross-section survey, no visual indications of instability within
permanent cross-sections 7 or 8 were observed by field personnel.
1.1.3 Additional Permanent Cross-sections
In addition to aforementioned cross-sections (1, 2, 7 and 8) 14 of the original 34
permanent cross-sections were also re -surveyed at the end of Year 5 to record changes
within each respective headwater valley (no riffle or pool cross sections). These cross-
sections were established and surveyed following construction and were not monitored
again until Year 5. The cross-sections are located as follows: cross-sections 3, 4, 5, and
6 (Scott Creek), cross-section 11 (UT1), cross-sections 13, 14 and 16 (UT3), cross-
section 21 (UT4), cross-section 24 (UT6), cross-section 29 (UT7) and cross-sections 30,
31 and 32 (UT8). Graphs of these 14 monitored cross-sections are presented in this
report.
These 14 cross-sectional surveys were completed to document observations by field
personnel throughout the Year 5 monitoring period. According to the Year 5 survey,
some of the valley cross-sections underwent slight to significant changes, while others
remained relatively unchanged. Some cross-sections were noted to have experienced
observable increases or decreases in thalweg elevations and/or ground elevations.
According to the survey data, five (3, 4, 5, 11 and 21) cross-sections of the additional 14
cross-sections displayed notable changes that were documented during the Year 5
survey. The changes within these 5 valley cross-sections are briefly described below.
Following the Year 5 monitoring period, it was noted that cross-sections 3 and 4 in upper
Scott Creek valley showed some slight aggradation within the valley bottoms since their
as built condition. However, according to the data, a small channel seems to be
developing in the aggraded areas within each respective cross-section. Even though
some slight aggradation has occurred, the Year 5 thalweg elevations of cross-sections 3
and 4 are relatively the same as was measured in the as -built. Overall, both cross-
sections appear to be stable and functioning as designed.
The survey data for cross-section 5 (just downstream from 3 and 4 in upper Scott Creek)
shows that the soil depths within the valley bottom are somewhat uneven and that soils
have adjusted at different rates. This natural microtopographic variability is common
within multi -thread headwater valley systems. The thalweg in this cross-section is at
relatively the same elevation as was measured following construction. No apparent
issues were noted in the vicinity of cross-section 5 during the Year 5 survey.
Similarly, the survey data for cross-section 11 (lower UT1 valley), shows that the soil in
this area has adjusted at different rates. It is noted that the thalweg in this cross-section
is at a slightly lower elevation than was measured immediately following construction.
Following Year 5 monitoring, cross-section 21 (mid -valley UT4) shows that the soil along
the right bank of the valley has experienced some aggradation and a defined channel is
not discernable within the survey data. The aggradation observed within cross-section
21 is at this time attributed to the location of the cross-section on the downstream portion
of UT4. This area likely experienced a period of sediment deposition following
construction and has since stabilized.
Hell Swamp/Scott Creek Mitigation Site Appendix A - 3 PCS Phosphate Company, Inc.
Fifth Annual and Summary Report February 2016

According to the survey data, the remaining 9 cross-sections (6, 13, 14, 16, 24, 29, 30,
31 and 32) displayed minor changes since as -built conditions. These cross-sections
seem to be relatively stable and are functioning as designed. During the Year 5 survey,
field personnel did not observe any noticeable issues or instability within the headwater
valleys where the 14 cross-section were taken.
1.1.4 Areas of Concern
No areas of concern have been identified for the restored headwater prongs.
Hell Swamp/Scott Creek Mitigation Site Appendix A - 4 PCS Phosphate Company, Inc.
Fifth Annual and Summary Report February 2016

B
Sc
Legend
Valley Cross-sections
Valley Cross-sections Surveyed for Year 5
NOTE:
POST -CONSTRUCTION CONTOURS WERE
DEVELOPED FROM LIDAR DATA COLLECTED
BY TUCK MAPPING SOLUTIONS INC.AND
PROCESSED BY MATRIX EAST,LLC.
Michael Baker Engineering, Inc. Figure
- SOncyParkway
.600 0 750 1,500 3,000 Year 5 Cross-sections
Cary., North Carolina 27518
Pho"9:919463.5488 Feet Monitoring Map
Fax: 919 463
Hell Swamp Mitigation Site
Hell Swamp/Scott Creek Mitigation Site Appendix A - 5 PCS Phosphate Comoanv, Inc.
Fifth Annual and Summary Report February 2016

Year 5Cross-section Monitoring
Graphs
NOTE: All cross section graphs show the "downstream view" across valley/stream
(e.g., left side of graph = left bank/valley)
Hell Swamp/Scott Creek Mitigation Site Appendix A - 6 PCS Phosphate Company, Inc.
Fifth Annual and Summary Report February 2016

10
9
8
0
> 7
ID
W
6
5
0
8
7
� 6
_
0
�s
> 5
m
W
4
3
0
Hell Swamp Cross-section 1
Scott Creek (Station 14+50)
—As -Built
—Year 3
--*.--Year 5
50 100 150 200 250 300 350 400 450 500
Station (ft)
Hell Swamp Cross-section 2
Scott Creek (Station 20+20)
—As -Built
—Year 3
--*--Year 5
50 100 150 200 250 300 350 400 450
Station (ft)
Hell Swamp/Scott Creek Mitigation Site Appendix A - 7 PCS Phosphate Company, Inc.
Fifth Annual and Summary Report February 2016

7
6
5
c
0
4 -
CU
> 4
Q
LU
3
2
0
7
6
5
c
0
�a
> 4
0
LU
3
2
0
Hell Swamp Cross-section 3
Scott Creek (Station 26+65)
Station (ft)
Hell Swamp Cross-section 4
Scott Creek (Station 31+55)
Station (ft)
—As -Built +Year 5
—As -Built Year 5
Hell Swamp/Scott Creek Mitigation Site Appendix A - 8 PCS Phosphate Company, Inc.
Fifth Annual and Summary Report February 2016

7
6
5
c
0
ca
> 4
d'
LU
3
2
d
7
6
5
c
0
> 4
ID
LU
3
2
0
Hell Swamp Cross-section 5
Scott Creek (Station 37+25)
Station (ft)
Hell Swamp Cross-section 6
Scott Creek (Station 41+80)
Station (ft)
—As -Built tYear 5
—As -Built —Year 5
Hell Swamp/Scott Creek Mitigation Site Appendix A - 9 PCS Phosphate Company, Inc.
Fifth Annual and Summary Report February 2016

5
4
r-.
3
c
0
a 2
0
W
1
5
4
_ 3
C
0 2
ca
W 1
0
-1
Hell Swamp Cross-section 7
Scott Greek (Station 47+70)
Note: Floodprone width is defined as
the discharge level that is twice the
maximum bankfull depth
--------------------------- �4c----------------------------------------------------------------------- �s
50 100 150 200 250 300 350 400 450
Station (ft)
Hell Swamp Cross-section 8
Scott Greek (Station 52+85)
-------------------------------------
Note: Floodprone width is defined as
the discharge level that is twice the
maximum bankfull depth
0 50 100
150 200
Station (ft)
As -Built Year
Year 3 Year 4
o—Year 5 -- Bankfull
----- Floodprone
Hell Swamp/Scott Creek Mitigation Site Appendix A - 10 PCS Phosphate Company, Inc.
Fifth Annual and Summary Report February 2016

Hell Swamp Cross-section 11
UT1 (Station 20+50)
6
5
4
c
0
c+s
> 3
m
iL
2
—As -Built Year 5
0 50 100 150 200 250 300 350 400 450
Station (ft)
10
9
g
c
0
4 -
CU
> 7
ar
W
6
Hell Swamp Cross-section 13
UT3 (Station 18+60)
25 50 75
100
Station (ft)
—As -Built +Year 5
125 150 1175 200
Hell Swamp/Scott Creek Mitigation Site Appendix A - 11 PCS Phosphate Company, Inc.
Fifth Annual and Summary Report February 2016

Hell Swamp Crass -section 14
UT3 (Station 24+30)
9
8
7
c
a
ca
a>i 6
LU
5
As -Built Year 5
4
0 25 50 75 100 125 150 175 200 225
Station (ft)
8
7
6
c
0
cu
> 5
Q
W
4
3
Hell Swamp Cross-section 16
UT3 (Station 36+35)
0 50 100 150 200 250
Station (ft)
—As -Built +Year 5
300 350 400
Hell Swamp/Scott Creek Mitigation Site Appendix A - 12 PCS Phosphate Company, Inc.
Fifth Annual and Summary Report February 2016

Hell Swamp Cross-section 21
UT4 (Station 15+85)
5
4
3
_
0
c+s
> 2
m
iL
1
—As -Built =Year 5
0 50 100 150 200
Station (ft)
Hell Swamp Cross-section 24
UT6 (Station 19+95)
5
4
3
0
c�
> 2
0
W
1
—As -Built +Year 5
0
0 25 50 75 100 125 150 175 200 225
Station (ft)
Hell Swamp/Scott Creek Mitigation Site Appendix A - 13 PCS Phosphate Company, Inc.
Fifth Annual and Summary Report February 2016

6
5
4
0
c�
> 3
W
LU
2
1
Hell Swamp Gross -section 29
UT7 (Station 19+15)
0 25 50 75
100
Station (ft)
—As -Built +Year 5
125 150 175 240 I
Hell Swamp Cross-section 30
UT8 (Station 13+15)
7
6
5
c
a
co
a 4
as
LU
3
—As -Built Year 5
2
0 25 50 75 100 125 150 175 200 225
Station (ft)
Hell Swamp/Scott Creek Mitigation Site Appendix A - 14 PCS Phosphate Company, Inc.
Fifth Annual and Summary Report February 2016

7
6
5
c
0
4 -
ca
> 4
0
W
3
al,
6
5
4
0
c�
> 3
ID
W
2
1
Hell Swamp Crass -section 31
UT8 (Station 17+90)
—As -Built �►-Year 5
25 50 75 100 125 150 175 200 225
Station (ft)
Hell Swamp Cross-section 32
UT8 (Station 23+35)
0 25 50 75
100
Station (ft)
—As -Built —Year 5
125 150 175 200
Hell Swamp/Scott Creek Mitigation Site Appendix A - 15 PCS Phosphate Company, Inc.
Fifth Annual and Summary Report February 2016