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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
Object Description
Description
Title | Annual report for... Mile Branch, Guilford County, TIP no. R-0609IA |
Other Title | Mile Branch, Guilford County |
Date | 2012-12 |
Description | 2012 |
Digital Characteristics-A | 1.93 MB; 23 p. |
Digital Format |
application/pdf |
Related Items | http://worldcat.org/oclc/862947383/viewonline |
Pres File Name-M | pubs_serial_milebranch201212.pdf |
Full Text | 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 |
OCLC number | 862947383 |