Annual report for... Southwest Creek mitigation site, Lenoir County, project no. 6.201014, TIP no. R-2001B |
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ANNUAL REPORT FOR 2007 Southwest Creek Mitigation Site Lenoir County TIP No. R-2001B Prepared By: Natural Environment Unit & Roadside Environmental Unit North Carolina Department of Transportation January 2007 TABLE OF CONTENTS SUMMARY...................................................................................................................... 1 1.0 INTRODUCTION.................................................................................................. 2 1.1 Project Description..................................................................................... 2 1.2 Purpose ..................................................................................................... 2 1.3 Project History ........................................................................................... 2 2.0 HYDROLOGY....................................................................................................... 4 2.1 Success Criteria......................................................................................... 4 2.2 Hydrologic Description............................................................................... 4 2.3 Results of Hydrologic Monitoring ............................................................... 6 2.3.1 Site Data ......................................................................................... 6 2.3.2 Climatic Data................................................................................... 6 2.4 Conclusions ............................................................................................... 6 3.0 VEGETATION .................................................................................................... 10 3.1 Success Criteria....................................................................................... 10 3.2 Description of Species ............................................................................. 10 3.3 Results of Vegetation Monitoring ............................................................. 10 3.4 Conclusions ............................................................................................. 11 4.0 OVERALL CONCLUSIONS/RECOMMENDATIONS.......................................... 11 LIST OF FIGURES Figure 1. Site Location Map ........................................................................................... 3 Figure 2. Gauge Location Map....................................................................................... 5 Figure 3. 2006 Hydrologic Monitoring Gauge Results................................................... 8 Figure 4. 30-70 Percentile Graph ................................................................................... 9 LIST OF TABLES Table 1. Hydrologic Monitoring Results.......................................................................... 6 Table 2. Hydrologic Monitoring Results (2003-2007) ...................................................... 6 Table 3. Vegetation Monitoring Statistics ..................................................................... 10 APPENDICES APPENDIX A GAUGE DATA GRAPHS APPENDIX B SITE PHOTOGRAPHS, PHOTO & PLOT LOCATIONS 1 SUMMARY The following report summarizes the monitoring activities that have occurred in the past year for the Southwest Creek mitigation site. Monitoring activities in 2007 represent the fifth year of monitoring for the site. The site must demonstrate both hydrologic and vegetation success for a minimum of five years or until the site is deemed successful. On May 15, 2003, two groundwater gauges, two surface water gauges, and one rain gauge were installed to monitor the site for hydrologic success. One groundwater gauge of the two in the forested wetland met the requirement for jurisdictional wetland hydrology (12.5% of the growing season). Gauge GW-1 recorded hydrology for 17.6%, while GW-2 recorded hydrology for 3.7% of the growing season. However, due to the drought conditions that occurred in 2007, the site recorded below average rainfall. The restored marsh gauge (SG-1) was comparable with the flooding patterns and inundation periods from the reference marsh gauge (SG-2). There were two vegetation monitoring plots established throughout the 2.9 acre planting area. The 2007 vegetation monitoring of the site revealed an average tree density of 680 trees per acre. This average is well above the minimum success criteria of 240 trees per acre. Base on five years of successful monitoring results, NCDOT recommends discontinuing hydrologic and vegetation monitoring at the Southwest Creek mitigation site. 2 1.0 INTRODUCTION 1.1 Project Description The Southwest Creek mitigation site consists of two areas that serve as onsite mitigation for the NC 11 Deep Run Bypass (Figure 1). The Southwest Creek site includes approximately 43.1 acres of wetland preservation and approximately 3.61 acres of wetland restoration. The site consists of the former NC 11 road bed that has been graded to meet the elevations of surrounding wetlands. 1.2 Purpose In order to demonstrate successful mitigation, the site must be monitored for a minimum of five years or until success criteria are achieved. Success criteria are based on federal guidelines for wetland mitigation and are stipulated in the approved mitigation plan and in relevant environmental permits. Criteria for both hydrologic conditions and vegetation survival are included in these documents. Included in this report are analyses of both hydrologic and vegetative monitoring results, as well as local climate conditions throughout the growing season. 1.3 Project History April 2003 Site Planted May 2003 Monitoring Gauges Installed May-November 2003 Hydrologic Monitoring (Year 1) July 2003 Vegetation Monitoring (Year 1) May-November 2004 Hydrologic Monitoring (Year 2) September 2004 Vegetation Monitoring (Year 2) March-November 2005 Hydrologic Monitoring (Year 3) September 2005 Vegetation Monitoring (Year 3) March-November 2006 Hydrologic Monitoring (Year 4) August 2006 Vegetation Monitoring (Year 4) March-November 2007 Hydrologic Monitoring (Year 5) June 2007 Vegetation Monitoring (Year 5) 3 Figure1. Site Location Map 4 2.0 HYDROLOGY 2.1 Success Criteria The Southwest Creek site has different success criteria to account for both marsh and swamp areas. In accordance with federal guidelines for wetland mitigation, the success criteria for hydrology state that the area must be inundated or saturated (within 12 inches of the surface) by surface or groundwater for at least a consecutive 12.5% of the growing season during years of normal rainfall. Hydrologic success criteria for the swamp area are consistent with federal guidelines. As was stated in the March 2000 mitigation plan, the success of the restored marsh will be determined by comparing the hydrologic data (by demonstrating patterns of flooding or inundation) to that recorded within the reference marsh system adjacent to the site. According to the Soil Conservation Service, the growing season in Lenoir County extends from March 17 to November 15, approximately 244 days. Thirty-one consecutive days would equal 12.5% of the growing season for Southwest Creek. Local climate must represent average conditions for the area in order for the hydrologic data to be valid. Average conditions are determined through an analysis of monthly rainfall totals recorded at the nearest official weather station. 2.2 Hydrologic Description Two groundwater gauges are being used to measure groundwater levels within the forested wetland portions. Two additional surface gauges are located within the marsh area. One surface gauge is in the restored area and another gauge serves as a reference within the existing marsh (reference marsh) adjacent to the site. The data from the two surface gauges are compared to determine the success of the marsh portion. A rain gauge is also located within the swamp area in order to obtain accurate site rainfall measurements. The site rainfall data is used to analyze the site’s (specifically, the swamp portion) response to rainfall events. Figure 2 is a map showing the location of all of the site gauges. Appendix A contains a plot of the water depth for each of the groundwater and surface water monitoring gauges. Precipitation events, measured by the onsite rain gauge, are included on each groundwater gauge graph as bars. 5 6 2.3 Results of Hydrologic Monitoring 2.3.1 Site Data The total number of consecutive days that the groundwater was within twelve inches of the surface was determined at each groundwater monitoring gauge location. This number was converted into a percentage of the total growing season. Table 1 presents the hydrologic results for 2007. Figure 3 is a graphical representation of the hydrologic monitoring results for 2007. Table 1. Hydrologic Monitoring Results Monitoring Gauge < 5% 5-8% 8-12.5% >12.5% Actual % Dates of Success SW-GW1 r 17.6 March 17-Apr 28 SW-GW2 r 3.7 Table 2. Hydrologic Monitoring Results (2003-2007) Monitoring Gauge 2003 Results 2004 Results 2005 Results 2006 Results 2007 Results SW-GW1 75.4 38.9 36.9 46.3 17.6 SW-GW2 75.4 35.6 76.6 31.1 3.7 Average Rainfall Average Rainfall Average Rainfall Average Rainfall Below Average 2.3.2 Climatic Data Figure 4 is a comparison of monthly rainfall for the period of January through November 2006 to historical precipitation (collected between 1975 and 2006) for Kinston, North Carolina. This comparison gives an indication of how 2007 relates to historical data in terms of climate conditions. The NC State Climate Office provided all local rainfall information. For the 2007-year, the month of May experienced above average rainfall. The months of January, April, June, July, and October recorded average rainfall for the site. February, March, August, September, and November experienced below average rainfall. Overall, 2007 experienced a below average rainfall year. 2.4 Conclusions The 2007-year represents the fifth full growing season for which the hydrologic data has been examined. One groundwater gauge of the two in the forested wetland met the requirement for jurisdictional wetland hydrology (12.5% of the growing season). Gauge GW-1 recorded hydrology for 17.6%, while GW-2 recorded hydrology for 3.7% of the growing season. The restored marsh gauge 7 (SG-1) was comparable with the flooding patterns and inundation periods from the reference marsh gauge (SG-2). NCDOT recommends discontinuing hydrologic monitoring at the Southwest Creek mitigation site. 8 9 Figure 4. 30-70 Percentile Graph 10 3.0 VEGETATION: SOUTHWEST CREEK MITIGATION SITE (YEAR 5 MONITORING) 3.1 Success Criteria The success criteria state that at least 320 stems per acre must survive after the completion of the third growing season and 240 stems per acre after the fifth growing season. If desired vegetation has not been established, NCDOT will notify the appropriate agencies and will implement corrective measures. 3.2 Description of Species The following tree species were planted in the Wetland Restoration Area: Fraxinus pennsylvanica, Green Ash Taxodium distichum, Bald cypress Quercus lyrata, Overcup Oak Nyssa aquatica, Water Tupelo 3.3 Results of Vegetation Monitoring Table 3. Vegetative Monitoring Statistics Site Notes: Overcup oak and water tupelo were noted living outside of plots even though very few were noted in the stem counts. Other species noted: cattail, Juncus sp., Scirpus sp., black willow, broomsedge, woolgrass, fennel, goldenrod, trumpet creeper, sedge, water grass, smart weed, laurel oak, tulip poplar, Baccharis sp., indian grass, wax myrtle, red maple, sweetgum, and various grasses. Plot # Green Ash Baldcypress Overcup Oak Water Tupelo Total (5 year) Total (at planting) Density (Trees/Acre) 1 14 21 1 1 37 37 680 2 15 21 3 1 40 40 680 6 8 0 A v e r a g e D e n s i ty ( T re e s /A c re ) 11 3.4 Conclusions There were 2 vegetation monitoring plots established throughout the 2.9 acre planting area. The 2007 vegetation monitoring of the site revealed an average tree density of 680 trees per acre. This average is well above the minimum success criteria of 240 trees per acre for Year 5. NCDOT recommends discontinuing vegetation monitoring at Southwest Creek mitigation site. 4.0 OVERALL CONCLUSIONS/RECOMMENDATIONS The following report summarizes the monitoring activities that have occurred in the past year for the Southwest Creek mitigation site. Monitoring activities in 2007 represent the fifth year of monitoring for the site. The site must demonstrate both hydrologic and vegetation success for a minimum of five years or until the site is deemed successful. The fifth year of monitoring indicated marginal hydrologic success, with one of the two groundwater gauges in the forested wetland area meeting the success criteria (within 12” of the surface for 12.5% of the growing season). The groundwater gauges revealed saturation levels of 17.6% and 3.7% of the growing season. However, due to the drought conditions that occurred in 2007, the site recorded below average rainfall. In accordance with the mitigation plan, the restored marsh gauge (SG-1) was comparable with the flooding patterns and inundation periods of the reference marsh gauge (SG-2). There were two vegetation monitoring plots established throughout the 2.9 acre planting area. The 2007 vegetation monitoring of the site revealed an average tree density of 680 trees per acre. This average is well above the minimum success criteria of 240 trees per acre. Based on five years of successful monitoring results, NCDOT recommends discontinuing hydrologic and vegetation monitoring at the Southwest Creek mitigation site. APPENDIX A GAUGE DATA GRAPHS APPENDIX B SITE PHOTOGRAPHS, PHOTO & PLOT LOCATIONS SOUTHWEST CREEK Photo 1 Photo 2 June 2006 APPENDIX A GAUGE DATA GRAPHS GROUNDWATER GAUGES SURFACE WATER GAUGES
Object Description
Description
Title | Annual report for... Southwest Creek mitigation site, Lenoir County, project no. 6.201014, TIP no. R-2001B |
Other Title | Southwest Creek mitigation site, Lenoir County |
Date | 2007-01 |
Description | 2007 |
Digital Characteristics-A | 934 KB; 26 p. |
Digital Format | application/pdf |
Pres File Name-M | pubs_serial_southwestcreekmitigation2007.pdf |
Pres Local File Path-M | \Preservation_content\StatePubs\pubs_borndigital\images_master\ |
Full Text | ANNUAL REPORT FOR 2007 Southwest Creek Mitigation Site Lenoir County TIP No. R-2001B Prepared By: Natural Environment Unit & Roadside Environmental Unit North Carolina Department of Transportation January 2007 TABLE OF CONTENTS SUMMARY...................................................................................................................... 1 1.0 INTRODUCTION.................................................................................................. 2 1.1 Project Description..................................................................................... 2 1.2 Purpose ..................................................................................................... 2 1.3 Project History ........................................................................................... 2 2.0 HYDROLOGY....................................................................................................... 4 2.1 Success Criteria......................................................................................... 4 2.2 Hydrologic Description............................................................................... 4 2.3 Results of Hydrologic Monitoring ............................................................... 6 2.3.1 Site Data ......................................................................................... 6 2.3.2 Climatic Data................................................................................... 6 2.4 Conclusions ............................................................................................... 6 3.0 VEGETATION .................................................................................................... 10 3.1 Success Criteria....................................................................................... 10 3.2 Description of Species ............................................................................. 10 3.3 Results of Vegetation Monitoring ............................................................. 10 3.4 Conclusions ............................................................................................. 11 4.0 OVERALL CONCLUSIONS/RECOMMENDATIONS.......................................... 11 LIST OF FIGURES Figure 1. Site Location Map ........................................................................................... 3 Figure 2. Gauge Location Map....................................................................................... 5 Figure 3. 2006 Hydrologic Monitoring Gauge Results................................................... 8 Figure 4. 30-70 Percentile Graph ................................................................................... 9 LIST OF TABLES Table 1. Hydrologic Monitoring Results.......................................................................... 6 Table 2. Hydrologic Monitoring Results (2003-2007) ...................................................... 6 Table 3. Vegetation Monitoring Statistics ..................................................................... 10 APPENDICES APPENDIX A GAUGE DATA GRAPHS APPENDIX B SITE PHOTOGRAPHS, PHOTO & PLOT LOCATIONS 1 SUMMARY The following report summarizes the monitoring activities that have occurred in the past year for the Southwest Creek mitigation site. Monitoring activities in 2007 represent the fifth year of monitoring for the site. The site must demonstrate both hydrologic and vegetation success for a minimum of five years or until the site is deemed successful. On May 15, 2003, two groundwater gauges, two surface water gauges, and one rain gauge were installed to monitor the site for hydrologic success. One groundwater gauge of the two in the forested wetland met the requirement for jurisdictional wetland hydrology (12.5% of the growing season). Gauge GW-1 recorded hydrology for 17.6%, while GW-2 recorded hydrology for 3.7% of the growing season. However, due to the drought conditions that occurred in 2007, the site recorded below average rainfall. The restored marsh gauge (SG-1) was comparable with the flooding patterns and inundation periods from the reference marsh gauge (SG-2). There were two vegetation monitoring plots established throughout the 2.9 acre planting area. The 2007 vegetation monitoring of the site revealed an average tree density of 680 trees per acre. This average is well above the minimum success criteria of 240 trees per acre. Base on five years of successful monitoring results, NCDOT recommends discontinuing hydrologic and vegetation monitoring at the Southwest Creek mitigation site. 2 1.0 INTRODUCTION 1.1 Project Description The Southwest Creek mitigation site consists of two areas that serve as onsite mitigation for the NC 11 Deep Run Bypass (Figure 1). The Southwest Creek site includes approximately 43.1 acres of wetland preservation and approximately 3.61 acres of wetland restoration. The site consists of the former NC 11 road bed that has been graded to meet the elevations of surrounding wetlands. 1.2 Purpose In order to demonstrate successful mitigation, the site must be monitored for a minimum of five years or until success criteria are achieved. Success criteria are based on federal guidelines for wetland mitigation and are stipulated in the approved mitigation plan and in relevant environmental permits. Criteria for both hydrologic conditions and vegetation survival are included in these documents. Included in this report are analyses of both hydrologic and vegetative monitoring results, as well as local climate conditions throughout the growing season. 1.3 Project History April 2003 Site Planted May 2003 Monitoring Gauges Installed May-November 2003 Hydrologic Monitoring (Year 1) July 2003 Vegetation Monitoring (Year 1) May-November 2004 Hydrologic Monitoring (Year 2) September 2004 Vegetation Monitoring (Year 2) March-November 2005 Hydrologic Monitoring (Year 3) September 2005 Vegetation Monitoring (Year 3) March-November 2006 Hydrologic Monitoring (Year 4) August 2006 Vegetation Monitoring (Year 4) March-November 2007 Hydrologic Monitoring (Year 5) June 2007 Vegetation Monitoring (Year 5) 3 Figure1. Site Location Map 4 2.0 HYDROLOGY 2.1 Success Criteria The Southwest Creek site has different success criteria to account for both marsh and swamp areas. In accordance with federal guidelines for wetland mitigation, the success criteria for hydrology state that the area must be inundated or saturated (within 12 inches of the surface) by surface or groundwater for at least a consecutive 12.5% of the growing season during years of normal rainfall. Hydrologic success criteria for the swamp area are consistent with federal guidelines. As was stated in the March 2000 mitigation plan, the success of the restored marsh will be determined by comparing the hydrologic data (by demonstrating patterns of flooding or inundation) to that recorded within the reference marsh system adjacent to the site. According to the Soil Conservation Service, the growing season in Lenoir County extends from March 17 to November 15, approximately 244 days. Thirty-one consecutive days would equal 12.5% of the growing season for Southwest Creek. Local climate must represent average conditions for the area in order for the hydrologic data to be valid. Average conditions are determined through an analysis of monthly rainfall totals recorded at the nearest official weather station. 2.2 Hydrologic Description Two groundwater gauges are being used to measure groundwater levels within the forested wetland portions. Two additional surface gauges are located within the marsh area. One surface gauge is in the restored area and another gauge serves as a reference within the existing marsh (reference marsh) adjacent to the site. The data from the two surface gauges are compared to determine the success of the marsh portion. A rain gauge is also located within the swamp area in order to obtain accurate site rainfall measurements. The site rainfall data is used to analyze the site’s (specifically, the swamp portion) response to rainfall events. Figure 2 is a map showing the location of all of the site gauges. Appendix A contains a plot of the water depth for each of the groundwater and surface water monitoring gauges. Precipitation events, measured by the onsite rain gauge, are included on each groundwater gauge graph as bars. 5 6 2.3 Results of Hydrologic Monitoring 2.3.1 Site Data The total number of consecutive days that the groundwater was within twelve inches of the surface was determined at each groundwater monitoring gauge location. This number was converted into a percentage of the total growing season. Table 1 presents the hydrologic results for 2007. Figure 3 is a graphical representation of the hydrologic monitoring results for 2007. Table 1. Hydrologic Monitoring Results Monitoring Gauge < 5% 5-8% 8-12.5% >12.5% Actual % Dates of Success SW-GW1 r 17.6 March 17-Apr 28 SW-GW2 r 3.7 Table 2. Hydrologic Monitoring Results (2003-2007) Monitoring Gauge 2003 Results 2004 Results 2005 Results 2006 Results 2007 Results SW-GW1 75.4 38.9 36.9 46.3 17.6 SW-GW2 75.4 35.6 76.6 31.1 3.7 Average Rainfall Average Rainfall Average Rainfall Average Rainfall Below Average 2.3.2 Climatic Data Figure 4 is a comparison of monthly rainfall for the period of January through November 2006 to historical precipitation (collected between 1975 and 2006) for Kinston, North Carolina. This comparison gives an indication of how 2007 relates to historical data in terms of climate conditions. The NC State Climate Office provided all local rainfall information. For the 2007-year, the month of May experienced above average rainfall. The months of January, April, June, July, and October recorded average rainfall for the site. February, March, August, September, and November experienced below average rainfall. Overall, 2007 experienced a below average rainfall year. 2.4 Conclusions The 2007-year represents the fifth full growing season for which the hydrologic data has been examined. One groundwater gauge of the two in the forested wetland met the requirement for jurisdictional wetland hydrology (12.5% of the growing season). Gauge GW-1 recorded hydrology for 17.6%, while GW-2 recorded hydrology for 3.7% of the growing season. The restored marsh gauge 7 (SG-1) was comparable with the flooding patterns and inundation periods from the reference marsh gauge (SG-2). NCDOT recommends discontinuing hydrologic monitoring at the Southwest Creek mitigation site. 8 9 Figure 4. 30-70 Percentile Graph 10 3.0 VEGETATION: SOUTHWEST CREEK MITIGATION SITE (YEAR 5 MONITORING) 3.1 Success Criteria The success criteria state that at least 320 stems per acre must survive after the completion of the third growing season and 240 stems per acre after the fifth growing season. If desired vegetation has not been established, NCDOT will notify the appropriate agencies and will implement corrective measures. 3.2 Description of Species The following tree species were planted in the Wetland Restoration Area: Fraxinus pennsylvanica, Green Ash Taxodium distichum, Bald cypress Quercus lyrata, Overcup Oak Nyssa aquatica, Water Tupelo 3.3 Results of Vegetation Monitoring Table 3. Vegetative Monitoring Statistics Site Notes: Overcup oak and water tupelo were noted living outside of plots even though very few were noted in the stem counts. Other species noted: cattail, Juncus sp., Scirpus sp., black willow, broomsedge, woolgrass, fennel, goldenrod, trumpet creeper, sedge, water grass, smart weed, laurel oak, tulip poplar, Baccharis sp., indian grass, wax myrtle, red maple, sweetgum, and various grasses. Plot # Green Ash Baldcypress Overcup Oak Water Tupelo Total (5 year) Total (at planting) Density (Trees/Acre) 1 14 21 1 1 37 37 680 2 15 21 3 1 40 40 680 6 8 0 A v e r a g e D e n s i ty ( T re e s /A c re ) 11 3.4 Conclusions There were 2 vegetation monitoring plots established throughout the 2.9 acre planting area. The 2007 vegetation monitoring of the site revealed an average tree density of 680 trees per acre. This average is well above the minimum success criteria of 240 trees per acre for Year 5. NCDOT recommends discontinuing vegetation monitoring at Southwest Creek mitigation site. 4.0 OVERALL CONCLUSIONS/RECOMMENDATIONS The following report summarizes the monitoring activities that have occurred in the past year for the Southwest Creek mitigation site. Monitoring activities in 2007 represent the fifth year of monitoring for the site. The site must demonstrate both hydrologic and vegetation success for a minimum of five years or until the site is deemed successful. The fifth year of monitoring indicated marginal hydrologic success, with one of the two groundwater gauges in the forested wetland area meeting the success criteria (within 12” of the surface for 12.5% of the growing season). The groundwater gauges revealed saturation levels of 17.6% and 3.7% of the growing season. However, due to the drought conditions that occurred in 2007, the site recorded below average rainfall. In accordance with the mitigation plan, the restored marsh gauge (SG-1) was comparable with the flooding patterns and inundation periods of the reference marsh gauge (SG-2). There were two vegetation monitoring plots established throughout the 2.9 acre planting area. The 2007 vegetation monitoring of the site revealed an average tree density of 680 trees per acre. This average is well above the minimum success criteria of 240 trees per acre. Based on five years of successful monitoring results, NCDOT recommends discontinuing hydrologic and vegetation monitoring at the Southwest Creek mitigation site. APPENDIX A GAUGE DATA GRAPHS APPENDIX B SITE PHOTOGRAPHS, PHOTO & PLOT LOCATIONS SOUTHWEST CREEK Photo 1 Photo 2 June 2006 APPENDIX A GAUGE DATA GRAPHS GROUNDWATER GAUGES SURFACE WATER GAUGES |
OCLC number | 870683160 |