RESTORATION PLAN Glade Creek Stream Restoration Alleghany ...

More documents

Recommendations

Info

6.3 HEC-RAS Analysis6.3.1 No-rise, LOMR, CLOMRAs of July 2, 2007, there is no FEMA mapping for the project area, based on a review of the N.C.Flood maps website. The proposed project is a Rosgen Priority II stream restoration project, withno wetland restoration component, only wetland preservation. The hydrology of the site will notbe significantly altered by the project. The Faw’s property and the adjoining properties will not behydrologically trespassed upon by the stream restoration project.HEC-RAS (USACE, 2001) was used to model water surface elevations for existing conditions fora variety of discharges generated from TR-20. The peak 1-, 2-, 10-, and 100-year stormdischarges were all modeled in HEC-RAS.An existing conditions topographic basemap for the project reach was constructed in ArcGIS bymerging the 1-foot contour interval channel survey conducted by Cavanaugh and Associates, PAwith the 10-foot contour interval Alleghany County map. For existing conditions, topographicinformation from the Cavanaugh survey superceded that of the County basemap. Thesebasemaps were then used in HEC-GeoRAS (version 3.1) to define and assemble the channelnetwork topology, cross-sections, and reach lengths. Cross-sections were located at hydrauliccontrol points (such as upstream and downstream of bridge culverts and at slope breaks), as wellas at intermediate locations to capture changes to channel and overbank geometry. The crosssectionswere oriented to be orthogonal to the local mean channel flow and anticipated overbankflow. Bridge and culvert geometry and hydraulic coefficients for the bridge were measured in thefield during a site visit conducted in the Spring of 2007. The site visit also provided informationon existing channel conditions and overbank vegetation so that the channel and overbankManning’s n-values could be estimated using a table of typical values found in Chow (1959).In the absence of paired discharge-stage flow measurements on Glade Creek, model boundaryconditions had to be assumed to be uniform flow with bed slopes estimated from the topographicbasemaps. A subcritical flow regime was modeled, as there were no significant areas that wouldwarrant calculations under mixed or supercritical conditions. Because of limited detailed surveydata beyond the reach extents, boundary conditions were calculated by assuming that a localslope at the top and the slope from the downstream end of the bridge to the bottom of the reachextended beyond the reach.6.4 Soil Restoration6.6.1 Topsoil Salvage, Soil Testing and Nutrient AmendmentsWhere grading is performed for channel stabilization, the overlying 4-6 inches of topsoil will bestockpiled for redistribution over the site after grading is complete. Soil samples were collectedonsite and were sent to the N.C. Department of Agriculture Soils Laboratory for analysis. Theanalysis report confirms the field assessment of the alluvial soils that occupy the project site, thatthey are loamy with a moderate to low bulk density and they will not require any morefertilization or lime application than is usually applied for tree seedling and live stakeestablishment.26
6.5 Natural Plant Community Restoration6.5.1 Narrative & Plant Community RestorationThe project site is approximately 2,600 feet above seal level, in the Blue Ridge Mountains. Theplanting schedule for riparian plantings (see Section 11, Table 6) reflects both thePiedmont/Mountain Levee Forest (Shafale and Weakley 1990) and the species already present onsite. The trees, mid-story trees and shrubs species listed for Zone 1, Riparian Woodlands-Mesicare all common to the area and easily observed nearby. Many of the species are good foodsources for wildlife and are adapted to the more well-drained areas of the site. The Zone 2-Floodplain Bench planting schedule lists a variety of willows, to be planted as live stakes toestablish root systems quickly, stabilizing the soil in the active channel. Tag or smooth alderand river birch are listed as sub-canopy and canopy species, respectively. These specieswill grow taller than the willows and provide additional shading of the channel over thelong term.6.5.2 On-site Invasive Species ManagementMultiflora rose is the only vegetative invasive species observed onsite, and it occurs mainly onthe downstream end of the project. Mechanical control and herbicide will be used to control thisspecies.27
Page 1 and 2: RESTORATION PLANGlade Creek Stream
Page 3 and 4: Table of ContentsExecutive Summary.
Page 5 and 6: Executive SummaryThe project site a
Page 7 and 8: 1.0 Project Site Identification and
Page 9 and 10: By far the most prevalent soil seri
Page 11 and 12: N.C. Natural Heritage Program List
Page 13 and 14: Bog turtles inhabit slow, shallow,
Page 15 and 16: control measure. There is no guaran
Page 17 and 18: the Mountain physiographic province
Page 19 and 20: 3.6 VegetationThe riparian area alo
Page 21 and 22: 4.5 VegetationThe forest canopy is
Page 23 and 24: 6.0 Project Site Restoration Plan6.
Page 25: o n' nDwhere all terms are as de
Page 29 and 30: 8.0 ReferencesBarnes, H.H. Jr., 196
Page 31 and 32: Wolman, M.G., and Miller, J.P., 196
Page 33 and 34: Table 4. Morphological TableTable 4
Page 35 and 36: Table 6. Designed Vegetative Commun
Page 37 and 38: TEMPORARY HERBACEOUS SEEDDateSpecie
Page 39 and 40: P a r k w a y¬« 18 £¤ 21SpartaD
Page 41 and 42: CeCCeECeCCdGWaFCaFWaEGlade CreekTlC
Page 43 and 44: WhiteheadWhitehead 7.5 Min Topo Qua
Page 45 and 46: ChDCeFCeFGrDChDCrFCoveChEDoughtonRe
Page 47: 11.0 Designed SheetsSheet 1. CoverS

RESTORATION PLAN Glade Creek Stream Restoration Alleghany ...

Create successful ePaper yourself

Delete template?

Save as template?