ANNUAL REPORT FOR 2012
Mile Branch
Guilford County
TIP No. R-0609IA
COE Action ID: 2004-00340
DWQ #: 2006-0331
Prepared By:
Natural Environment Section & Roadside Environmental Unit
North Carolina Department of Transportation
December 2012
TABLE OF CONTENTS
SUMMARY ........................................................................................................... 1
1.0 INTRODUCTION: ...................................................................................... 2
1.1 Project Description ......................................................................... 2
1.2 Purpose ........................................................................................ 2
1.3 Project History ............................................................................... 2
1.4 Debit Ledger ................................................................................... 2
2.0 STREAM ASSESSMENT: ......................................................................... 4
2.1 Success Criteria .............................................................................. 4
2.2 Stream Description ......................................................................... 4
2.2.1 Post-Construction Conditions .................................... 4
2.2.2 Monitoring Conditions ................................................ 4
2.3 Results of Stream Assessment ....................................................... 6
2.3.1 Site Data .................................................................... 6
2.4 Results of Stream and Buffer Vegetation ........................................ 7
2.4.1 Description of Species ............................................... 7
2.4.2 Results of Vegetation Monitoring ............................... 7
2.4.3 Conclusions ............................................................... 8
3.0 OVERALL CONCLUSIONS AND RECOMMENDATIONS ........................ 8
4.0 REFERENCES .......................................................................................... 9
LIST OF FIGURES
Figure 1 – Vicinity Map ........................................................................................ 3
TABLES
Table 1 – Abbreviated Morphological Summary .................................................. 5
APPENDICES
Appendix A – Cross Section Comparisons & Longitudinal Profile
Appendix B – Site Photographs, Cross Section & Photo Point Locations
1
SUMMARY
The following report summarizes the stream monitoring activities that have occurred
during 2012 at the Mile Branch Mitigation Site in Guilford County. The site was
constructed during 2008 by the North Carolina Department of Transportation (NCDOT).
This report provides the monitoring results for the fourth formal year of monitoring (Year
2012). The Year 2012 monitoring period is the fourth of five scheduled years for
monitoring on Mile Branch (See Success Criteria Section 2.1).
Based on the overall conclusions of monitoring along Mile Branch, the site has met the
required monitoring protocols for the fourth formal year of monitoring. Based on the
monitoring data, the channel is stable throughout the stream at this time. A bankfull
event has occurred since the last monitoring evaluation. NCDOT replanted the buffer in
January 2010 and replanted the streambank and buffer in March 2011 due to low tree
survival.
On April 30, 2010, NCDOT repaired an area of the stream at Sta. 11+64 due to a wash
out behind the cross vane arm. NCDOT repaired this area by placing boulders behind
the right arm of the vane and installed a sill at the end of the arm. Also the cross vane
at Sta. 11+42 had a boulder placed behind the left arm of the vane where washing had
occurred. N.C. Division of Water Quality and U.S. Army Corps of Engineers personnel
requested that this information be included in the monitoring report in lieu of completing
a permit modification.
In late March 2011, NCDOT repaired the scour on the right bank from approximately
11+70 to 11+83 by installing boulder toe protection. All disturbed areas were seeded
and matted. Live stakes and bare root seedlings were planted on March 29, 2011.
During the 2012 monitoring evaluation, there were two beaver dams noted onsite at
Photo Point #3 (large dam) and at Cross Section #3 (small dam) that have been
breached and beavers have been trapped and are continuing to be trapped by USDA.
DOT Maintenance is scheduled to remove the debris from the large dam so water can
access the floodplain. NCDOT plans to replant the areas disturbed by the beaver
activity with live stakes and bareroot seedlings by March 2013.
NCDOT will continue stream monitoring at the Mile Branch Mitigation Site in 2013.
2
1.0 INTRODUCTION
1.1 Project Description
The following report summarizes the stream monitoring activities that have occurred
during 2012 at the Mile Branch Mitigation Site. The site is located adjacent to the US
311 southbound lanes just east of SR 1158 Jackson Lake Road (Figure 1). The Mile
Branch Mitigation Site was constructed to provide mitigation for stream impacts
associated with Transportation Improvement Program (TIP) number R-0609IA in
Guilford County.
The mitigation project covers approximately 659 linear feet of stream relocation.
Construction was completed in August 2008 by the North Carolina Department of
Transportation (NCDOT). Stream restoration involved the installation of rock cross
vanes, rock sills, construction of a new stream channel and construction of the
floodplain to allow for overbank flooding. It also included the installation of coir fiber
matting and live stakes along the streambank and bareroot seedlings in the buffer area.
1.2 Purpose
In order for a mitigation site to be considered successful, the site must meet the
success criteria. This report details the monitoring in 2012 at the Mile Branch Mitigation
Site. Hydrologic monitoring was not required for the site.
1.3 Project History
August 2008 Construction Completed
January 2009 Planted Live Stakes and Bareroot Seedlings
September 2009 Stream Channel and Vegetation Monitoring (1 yr.)
January 2010
April 2010
Replanted Buffer
Streambank Repairs
October 2010
March 2011
March 2011
Stream Channel and Vegetation Monitoring (2 yr.)
Streambank Repairs
Replanted Streambank and Buffer
October 2011
September 2012
November 2012
Stream Channel and Vegetation Monitoring (3 yr.)
Vegetation Monitoring (4 yr.)
Stream Channel Monitoring (4 yr.)
1.4 Debit Ledger
The entire Mile Branch stream mitigation site was used for the R-0609IA project to
compensate for unavoidable stream impacts.
3
Figure 1. Vicinity Map
4
2.0 STREAM ASSESSMENT
2.1 Success Criteria
In accordance with the approved mitigation plan, NCDOT will evaluate the success of
the stream relocation project based on guidance provided by the Stream Mitigation
Guidelines disseminated by the United States Army Corps of Engineers-Wilmington
District. The survey of channel dimension will consist of permanent cross sections
placed at approximately four cross sections (two riffles and two pools). Annual
photographs showing both banks and upstream and downstream views will be taken
from permanent, mapped photo points. The survey of the longitudinal profile will
represent distinct areas of the stream and will cover a cumulative total of 632 linear feet
of channel. The entire restored length of stream will be investigated for channel stability
and in-stream structure functionality. Any evidence of channel instability will be
identified, mapped and photographed.
Vegetation Success
The success of vegetation plantings will be measured through stem counts. Permanent
quadrants will be used to sample the riparian buffer. Survival of the live stakes will be
determined by visual observation throughout the 5 year monitoring period.
Bareroot vegetation will be evaluated using 2 staked survival plots. Plots will be 50 ft.
by 50 ft. and all flagged stems will be counted in those plots. Success will be defined as
320 stems per acre after 5 years. All vegetation monitoring will be conducted during the
growing season.
2.2 Stream Description
2.2.1 Post-Construction Conditions
The mitigation project covers approximately 659 linear feet of stream relocation.
Construction was completed in August 2008 by the North Carolina Department of
Transportation (NCDOT). Stream restoration involved the installation of rock cross
vanes, rock sills, construction of a new stream channel and construction of the
floodplain to allow for overbank flooding. It also included the installation of coir fiber
matting and live stakes along the streambank and bareroot seedlings in the buffer area.
2.2.2 Monitoring Conditions
The objective of the Mile Branch Mitigation Site relocation was to build a C4 stream type
as identified in the Rosgen’s Applied River Morphology. A total of four cross sections
(two in a riffle, two in a pool) were surveyed. For this report, only cross sections
containing riffles were used in the comparison of channel morphology in Table 1.
5
Table 1. Abbreviated Morphological Summary
(Mile Branch Cross Sections #1 and #3)
Variable Proposed
Cross Section #1
(Riffle)
Cross Section #3
(Riffle)
Min. - Max Values
(Riffle Sections Only)
2012 2012 2012
Drainage Area (sq. mi) 2.24 2.24 2.24 2.24
Bankfull Width (ft) 21.2 25.74 20.94 20.94 – 25.74
Bankfull Mean Depth (ft) 1.77 1.08 1.72 1.08 – 1.72
Width/Depth Ratio 12 23.83 11.91 11.91 – 23.83
Bankfull Cross Sectional Area
(ft
2
)
37.1 27.84 35.27 27.84 – 35.27
Maximum Bankfull Depth (ft) 2.62 2.99 3.26 2.99 – 3.26
Flood prone Area (ft) 147.6 51 49.9 49.9 – 51
Entrenchment Ratio 6.98 1.98 2.44 1.98 – 2.44
*Drainage Area, Floodprone Width, and Slope are averaged values only.
*Riffle values are used for classification purposes.
6
2.3 Results of the Stream Assessment
2.3.1 Site Data
The assessment included the survey of four cross sections and the longitudinal profile
of Mile Branch established by the NCDOT after construction. The length of the profile
along Mile Branch was approximately 632 linear feet. Four cross sections were
established during the 2009 monitoring year. Cross section locations were subsequently
based on the stationing of the longitudinal profile and are presented below. The
location of the cross sections and longitudinal profile are shown in Appendix A.
¨ Cross Section #1. Mile Branch, Station 83+00 linear feet, midpoint of riffle
¨ Cross Section #2. Mile Branch, Station 340+00 linear feet, midpoint of pool
¨ Cross Section #3. Mile Branch, Station 412+00 linear feet, midpoint of riffle
¨ Cross Section #4. Mile Branch, Station 520+00 linear feet, midpoint of pool
Based on comparisons of the monitoring data, all four cross sections appear stable with
little or no active bank erosion. The floodplain on the right bank at Cross Section #4
had to be repaired after the as-built was completed. The right endpin at this cross
section had to be reset again due to the latest streambank repairs in March 2011. The
graph of Cross Section #4 shows this layout. Graphs of the cross sections are
presented in Appendix A. Future survey data will vary depending on actual location of
rod placement and alignment; however this information should remain similar in
appearance. The longitudinal profile shows that the channel is stable for the 2012
monitoring evaluation. A bankfull event has occurred since the last evaluation.
There were two beaver dams located onsite at Photo Point #3 (large dam) and at Cross
Section #3 (small dam) that have been breached and beavers have been trapped and
are continuing to be trapped by USDA. DOT Maintenance is scheduled to remove the
debris from the large dam so water can access onto the floodplain.
7
2.4 Results of Stream and Buffer Vegetation
2.4.1 Description of Species
The following live stake species were planted on the streambank:
Salix nigra, Black Willow
Cornus amomum, Silky Dogwood
The following tree species were planted in the buffer area:
Liriodendron tulipifera, Tulip Poplar
Platanus occidentalis, American Sycamore
Fraxinus pennsylvanica, Green Ash
Quercus phellos, Willow Oak
Nyssa sylvatica, Blackgum
Quercus lyrata, Overcup Oak
Betula nigra, River Birch
2.4.2 Results of Vegetation Monitoring
Buffer Vegetation: Two 50 ft. x 50 ft. vegetation plots were set to determine the trees
per acre in the buffer area.
Plot #
Tulip Poplar
American Sycamore
Green Ash
Willow Oak
Overcup Oak
River Birch
Blackgum
Total (Year 4)
Total (at planting)
Density (Trees/Acre)
1 2 6 14 2 1 25 45 378
2 6 12 9 3 12 5 1 48 55 593
486
Average
Density
(Trees/Acre)
8
Site Notes: The black willow and silky dogwood live stakes were surviving along the
streambank. Other vegetation noted included lespedeza, alder, goldenrod, pine, tear-thumb,
jewelweed, and various grasses. There is some planted vegetation missing in
the areas disturbed by the recent beaver activity.
2.4.3 Conclusions
There were two vegetation monitoring plots established throughout the buffer area. The
2012 vegetation monitoring of the site revealed an average tree density of 486 trees per
acre. This average is above the minimum success criteria of 320 trees per acre after
the fourth year of monitoring. NCDOT plans to replant the areas disturbed by the
beaver activity with live stakes and bareroot seedlings by March 2013. NCDOT will
continue to monitor the vegetation at the Mile Branch Mitigation Site.
3.0 OVERALL CONCLUSIONS/RECOMMENDATIONS
The Mile Branch Mitigation Site has met the required monitoring protocols for the fourth
formal year of monitoring. The channel and structures throughout the stream are stable
at this time.
Debris from the beaver dams is scheduled to be removed by DOT Maintenance and the
areas disturbed by the beaver activity will be replanted by March 2013.
NCDOT will continue stream monitoring at the Mile Branch Mitigation Site for 2013.
9
4.0 REFERENCES
Stream Mitigation Plan for Mile Branch (Permit Site 6); Guilford County, NC, September
11, 2006.
As-Built Report for Stream Restoration on R-609IA Permit Site 6, Guilford County, NC,
March 20, 2009.
Rosgen, D.L, 1996. Applied River Morphology. Wildland Hydrology, Pagosa Springs,
Colorado.
US Army Corps of Engineers (USACE), 2003. Stream Mitigation Guidelines. Prepared
with cooperation from the US Environmental Protection Agency, NC Wildlife
Resources Commission, and the NC Division of Water Quality.
APPENDIX A
CROSS SECTION COMPARISONS
&
LONGTITUDINAL PROFILE
Cross-Section #1 (Riffle) Abbreviated Morphological Summary
2009 2010 2011 2012 2013
Bankfull Width (ft) 26.3 26.9 27.4 25.74
Bankfull Mean Depth (ft) 1.4 1.06 0.99 1.08
Width/Depth Ratio 18.8 25.38 27.68 23.83
Bankfull Cross Sectional Area (ft2) 36.9 28.64 27.14 27.84
Maximum Bankfull Depth (ft) 2.86 2.91 3.09 2.99
Width of the Floodprone Area (ft) 51 51 51 51
Entrenchment Ratio 1.94 1.9 1.86 1.98
Cross-Section #2 (Pool) Abbreviated Morphological Summary*
2009 2010 2011 2012 2013
Bankfull Cross Sectional Area (ft2) 55 55.65 53.54 56.32
Maximum Bankfull Depth (ft) 4.89 4.89 4.84 4.98
Bankfull Mean Depth (ft) 2 1.26 1.95 2.02
Bankfull Width (ft) 27.52 27.69 27.52 27.83
* According to the Rosgen Classification of Natural Rivers floodprone width, entrenchement ratio,
and width depth ratio are not measured in pool, glide, or run features.
Cross-Section #3 (Riffle) Abbreviated Morphological Summary
2009 2010 2011 2012 2013
Bankfull Width (ft) 19.75 19.61 19.93 20.49
Bankfull Mean Depth (ft) 1.68 1.57 1.48 1.72
Width/Depth Ratio 11.76 12.49 13.47 11.91
Bankfull Cross Sectional Area (ft2) 33.15 30.76 29.6 35.27
Maximum Bankfull Depth (ft) 3 2.84 2.75 3.26
Width of the Floodprone Area (ft) 49.9 49.9 49.9 49.9
Entrenchment Ratio 2.53 2.54 2.5 2.44
Cross-Section #4 (Pool) Abbreviated Morphological Summary*
2009 2010 2011 2012 2013
Bankfull Cross Sectional Area (ft2) 23.18 36.71 28.62 30.6
Maximum Bankfull Depth (ft) 3.02 4.15 3.86 3.94
Bankfull Mean Depth (ft) 2.11 2.62 1.72 1.89
Bankfull Width (ft) 11 14 16.64 16.21
* According to the Rosgen Classification of Natural Rivers floodprone width, entrenchment ratio,
and width depth ratio are not measured in pool, glide, or run features.
APPENDIX B
SITE PHOTOGRAPHS, CROSS SECTION AND
PHOTO POINT LOCATIONS
Cross Section #3 at Station 4+95.6
Cross Section #7 at Station 17+75.6
Mile Branch
Photo Point #1 (Upstream) Photo Point #1 (Downstream)
Photo Point #2 (Upstream on Trib. 1) Photo Point #2 (Downstream on Trib. 1)
Photo Point #3 (Upstream) Photo Point #3 (Downstream)
November 2012
Mile Branch
Photo Point #4 (Upstream) Photo Point #4 (Downstream)
Photo Point #5 (Upstream on Main Channel) Photo Point #5 (Upstream on Trib. 2)
Photo Point #5 (Downstream on Main Channel)
November 2012
Mile Branch
Photo Point #6 (Upstream) Photo Point #6 (Downstream)
Large beaver dam @ PP#3 after breaching Overview of area disturbed by beavers
November 2012
Mile Branch
Large dam @ PP#3 prior to breaching Small dam @ XS#3 prior to breaching
Vegetation Plot #1 Vegetation Plot #2
Vegetation Overview Photo
September 2012