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HomeMy WebLinkAbout20051110 Ver 2_Restoration Plan_20080221 05- II to V~ Richland Creek Stream Restoration Plan Town of Wake Forest ~'~ ~ Wake County, North Carolina Under a grant from the North Carolina Clean Water Management Trust Fund ~~e ~ur~, ,~~ ~b ~ EprMy ~b^ • ~ ~ • EdunYOn ~Ya^ l ~~ ~t~rn u~~ ~~,~ Ff^~1.7.. ..N ~~ p~~ ~" D., Prepared By: ~ KCI Associates of North Carolina, P.A. Landmark Center II, Suite 220 ~~ 4601 Six Forks Road KCI Raleigh, NC 27609 June 2005 ~. TABLE OF CONTENTS 1.0 INTRODUCTION ...............................................................................................................1 1.1 Project Description ..............................................................................................................1 1.2 Project Goals and Objectives .............................................................................................1 1.3 Methodology ........................................................................................................................1 1.4 Qualifications .......................................................................................................................3 2.0 EXISTING CONDITIONS .................................................................................................3 2.1 Watershed ............................................................................................................................3 General Description ...............................................................................................................3 Geology and Soils .................................................................................................................4 Natural Communities ............................................................................................................4 Land Use ...............................................................................................................................7 2.2 Restoration Site ....................................................................................................................7 Site Description .....................................................................................................................7 Bankfull Verification .............................................................................................................7 Existing Stream Characteristics .............................................................................................8 Stability Assessment ..............................................................................................................8 Constraints ............................................................................................................................. 9 3.0 REFERENCE REACH ANALYSIS ..................................................................................9 3.1 Richland Creek Above Section 1 Reach (RCASIR) .........................................................9 3.2 Unnamed Tributary to Lake Wheeler (UTLW) ...............................................................11 4.0 NATURAL CHANNEL DESIGN ......................................................................................11 4.1 Design Methodology ............................................................................................................11 4.2 Richland Creek Restoration Design ...................................................................................11 4.3 Riparian Buffers ..................................................................................................................15 5.0 SEDIMENT TRANSPORT ................................................................................................15 6.0 FLOODING ANALYSIS ....................................................................................................16 7.0 MONITORING AND EVALUATION ..............................................................................16 7.1 Stream Monitoring ..............................................................................................................18 7.2 Vegetation Monitoring ........................................................................................................18 S.0 REFERENCES ....................................................................................................................19 LIST OF FIGURES Figure 1. Vicinity Map ....................................................................................................................2 Figure 2. Watershed Boundary ......................................................................................................5 Figure 3. Watershed Soils ...............................................................................................................6 Figure 4. Richland Creek Above Section 1 Reach (RCASIR) .....................................................10 Figure 5. Unnamed Tributary to Lake Wheeler (UTLW) ...........................................................12 Figure 6. Priority Levels of Incised River Restoration ................................................................14 Figure 7. River State Diagram .......................................................................................................17 LIST OF TABLES Table 1. Morphological Design Criteria ........................................................................................13 APPENDICES 1. Richland Creek Hydrograph (June -October 2004) 2. Site Photograph Documentation 3. Restoration Design Plan Set 1.0 INTRODUCTION The Town of Wake Forest (TWF) has contracted KCI Associates of North Carolina, P.A. (KCI) to provide professional assessment and design services on two separate reaches (Sections 1 and 2) of Richland Creek in Wake Forest, Wake County, North Carolina. The project has been funded by a grant from the North Carolina Clean Water Management Trust fund (CWMTF). The following restoration plan was prepared as a comprehensive design document to facilitate the permitting of the proposed project. 1.1 Project Description The proposed stream restoration is part of a stream/riparian buffer preservation and greenway project along the portion of Richland Creek that extends from the Franklin/Wake County Line (County Line) to Durham Road (NC 98) (Figure 1. Vicinity Map). As a component of this project, two sections of degraded channel are being restored. Section 1 is comprised of 6501inear feet (LF) of degraded channel (542 LF restoration) that begins approximately 2,700 feet downstream of the County Line. Section 2 includes the 1,900 LF reach (1,875 LF restoration) immediately upstream of the Stadium Drive Bridge. 1.2 Project Goals and Objectives The goals and objectives of the Richland Creek Stream Restoration Project are: ^ Improve water quality and reduce land and riparian vegetation loss resulting from lateral erosion and bed degradation; ^ Restore a stable channel morphology that is capable of moving the flows and sediment provided by its watershed; ^ Improve aquatic habitat; and, ^ Provide educational opportunities (to be directed through TWF). 1.3 Methodology An assessment of Richland Creek was initiated by obtaining available site and watershed data in order to define the current and anticipated conditions in which the restored stream system would need to function. This information included but was not limited to soils and geologic mapping, hydraulic and hydrologic (H&H) reports, floodplain mapping, land use/land cover mapping, regional hydraulic geometry data, and historic aerial photography. Data was collected following the methods prescribed in Applied River Morphology (Rosgen, 1996). As part of this assessment (Level III), existing morphologic characteristics were measured and used to classify the channel and make predictions about the condition and behavior of the stream. Observed bankfull indicators were identified and surveyed in section and in profile. An estimate of the bankfull discharge was calculated based on bankfull stage, channel roughness, and bed slope using the Manning Equation. Field determinations were correlated with regional hydraulic geometry data and were calibrated using the River Analysis System (HEC-RAS) developed by the Army Corps of Engineers (ACOE). Sediment transport characteristics of the existing stream were evaluated by collecting and analyzing bed and bar materials and by installing and monitoring scour chains to evaluate depth of scour and volume of deposition. This sediment data was later used to validate the proposed design for transport competence and capacity. ~, ;' r Figure 1. Vicinity Map N Section 1 -Stations 10+00 to 15+42 N Section 2 -Station 60+00 to 78+75 1:36,000: 1 "=300' 3000 0 3000 Feet Source: USGS Topographical Quadrangles (Grissom, Wake Forest, Rolesville, FranklintonJ Monitoring of surface water fluctuations was undertaken to understand the hydrologic response of the watershed and to verify the proposed design discharges. Two (2) surface water-monitoring gauges, one (1) barometric logger (required for gauge calibration), and one (1) rain gauge were used to perform this monitoring. Five months of continuous recordings (June through October) were utilized in this study. In-situ gauging with a Doppler velocity meter was used to calibrate the discharge estimates from these instruments. Two reference ecosystems with similar hydrogeomorphic parameters as the project site were identified and surveyed. The reference sites were used to define the morphological parameters (dimensionless ratios) that provide the basis (design criteria) for the restoration of Richland Creek. Additionally, design criteria were developed to address utilities and other issues (construction access) thaC could affect the proposed restoration. Stream restoration design plans were developed based upon the approved design criteria. These plans are presented on the project base mapping and depict the location, extent, and nature of the proposed modifications, including the proposed stream planform, typical cross-sections, and typical details for in-stream and bank stabilization structures/techniques. 1.4 Qualifications Qualifications for the primary specialists are provided as follows: Specialist: Gary M. Mryncza, Professional Hydrologist (P.H. - 1605) Education: MS, Water Resources, University of Birmingham (U.K.) BS, Natural Science, Towson University Experience: KCI, 1996 to present Specialist: Brian Hayes, Professional Geologist (P.G. - 1018) Education: BS, Geology, North Carolina State University Experience: KCI, 2004 to present Environmental Services, Inc. & NCDOT, 1995 to 2004 2.0 EXISTING CONDITIONS 2.1 Watershed General Description Richland Creek is situated within the northeastern portion of the Piedmont physiographic province, which is typified by rolling topography with broad ridges, sharply indented stream valleys, and narrow, low-gradient floodplains. The Richland Creek watershed (USGS 14-digit Hydrologic Unit 03020201070060) is located within sub-basin 03-04-02 of the Neuse River Basin. The headwaters of the Richland Creek form to the west and south of Youngsville, North Carolina. The watershed extends south-southwest to a point approximately 1.5 miles downstream of the Falls Reservoir Dam where Richland Creek joins the Neuse River. The North Carolina Division of Water Quality (NCDWQ) has classified Richland Creek, from its headwaters to its confluence with the Neuse River, as well as all tributaries, as Class C nutrient sensitive waters (NSW). NCDWQ has further assigned these streams a water quality use support rating of "support-threatened" with increasing watershed development and non-point source pollution as identified causes of probable impairment. The portion of Richland Creek evaluated as part of this project is located between the Franklin/Wake County Line and Stadium Drive in Wake Forest, North Carolina. Capital Boulevard (US 1) roughly bounds the watershed to the west and the Seaboard Coast Railroad Line bounds it to the east (Figure 2. Watershed Boundary). The topographic relief within the project reach is approximately 25 feet, ranging from approximately 282 feet above mean sea level (AMSL) at the upstream limits of Section 1 to 257 feet AMSL at the downstream limits at the Stadium Drive Bridge. Geology and Soils The Richland Creek Restoration Site lies within the Northern Outer Piedmont Ecoregion (Piedmont). This region is composed of mostly gneiss and schist rock intruded by granitic plutons and veneered with saprolite. At the eastern boundary, the Fall Line is a broad transition zone where Piedmont rocks occur on the same landscape with Coastal Plain sediments. Some areas near this boundary have meta-volcanic and meta-sedimentary rocks. The project area is part of the Cecil soil association. The Cecil association occurs on gently sloping to steep, deep, well-drained soils that have a subsoil of firm red clay; derived mostly from gneiss and schist. Soils that make up the rest of the association are mainly the Appling, Madison, Wedowee, Enon, Wilkes, Chewacla, Congaree, Wehadkee and Bibb. The Soil Survey of Wake County (USDA, 1970) has classified the soils underlying the majority of the site within the floodplain as Chewacla loam, 0 to 2 percent slopes, frequently flooded and the surrounding upland areas as Cecil sandy loam, 10- 15 percent slopes (Figure 3. Soils). Wehadkee soils were field mapped as inclusions in wetter areas. Preliminary verification of the soils in the study area was conducted based on field profile descriptions and the Wake County Soil Survey. Natural Communities A field survey was conducted to identify and document the dominant plant communities in the project area. Several distinct community mosaics were recognized, and complete species lists with dominance were compiled. These lists were utilized to best fit the communities described in the Classification of Natural Communities of North Carolina (Schafale & Weakley, 1990). Natural communities in the study area include Piedmont Levee Forest and Piedmont Bottomland Forest. Piedmont Levee Forests are prevalent along the active levee position of Richland Creek. Woody species of the canopy include Fraxinus pennsylvanica (green ash), Platanus occidentalis (sycamore), Betula nigra (river birch), Liquidambar styraciflua (sweet gum), Acer negundo (boxelder), and Juglans nigra (black walnut). Species in the overstory dominate those in the understory. The Piedmont Bottomland Forest, a PFOIA wetland type, is the natural community to the east of Richland Creek that occurs along perennial tributaries to Richland Creek. These Bottomland forests are located between the levees of Richland Creek and the major wetland areas that have 4 ;; ~J ~~. ,~ Wake County, North Carolina , : ~ ~. rr -,~ ', n ~- ~) ~ ,i 'Ii~~ l t ~ ~ ~. fit '~ ' ~~ -'°S;, ~ , s , y, { ~' , ~ ,~ '~ti> `t~,.. ~~ I ~'~ ~ ~; ~ ;~ ~ ,J. Y~ ~ ~~ ~ ~~~ .'ir i a ~f~ i i ~ f =^ei/b i/~~t?~i _S'ti _- ~ ~~~.~~ y -.- e~. ~~"1,. ,;t k~, l •I .: f," .r7 .! ,:y r;` . - ,;~=; `,ti, „ l Figure 2. Watershed Boundary Watershed Boundary N Restoration Section 1 1:36,000: 1 "=300' N Restoration Section 2 3000 0 3000 Feet Source.' USGS Topographical Quadrangles (Grissom, Wake Forest, Rolesville, Franklinton) " PP ~ y~ ~,. R+ 5' . i ~- r~°' ~ ~: w~'y ~K. ; ~. .: ; ~' /f ~}, ~'~ ,. i i+ ~~-'9'~ * a... ~~`~ ~+ .e ~~"~aw' Ark; '~ .y~, ~ w<!~""'i a~4"^ ~ °~ ~~~~ ~ ~_ ay, a ~-.-r,-,~. ~ ' ,~,. «r .a; ,i, .~ ~r ~ ~~ ~ ~r -.~ ~ r. ~ kJ S ~",` kry ~sS #x' '~^k~ ;~~'~L ~ ~ ~" F'`4i~ ~ ^. Figure 3. Soils ® Altavista fine sandy loam ~ Madison sandy loam ~ Appling sandy loam Mantachie soils D Cecil sandy loam Water D Chewacla soils ~ Wedowee soils ~ Enon fine sandy loam Wehadkee soils Faceville sandy loam ® Wilkes soils N Restoration Section 1 1000 0 1000 Feet N Restoration Section 2 Source.' Rake County G/S & Nonh Carolina Center jor Geographic lnjormaJion and Analysis been identified along the eastern boundary of the study area. The canopy is dominated by Liriodendron tulipifera (tulip tree), sweet gum, Ulmus Americana (American elm), Celtis laevigata, (sugarberry), green ash and Pinus taeda (loblolly pine) and the understory consists primarily of Carpinus caroliniana (musclewood) and Ilex opaca (American holly). Land Use Current land use in the contributing watershed consists of forest, cropland/pasture, and areas of suburban development. Historically, the area has been predominantly rural. However, development pressures in the area are significant. According to 2000 US Census figures, the population of the Town of Wake Forest more than doubled in the preceding decade (NCSDC, 2001). Recent growth in the watershed has included considerable commercial and residential development with associated road networks and utilities infrastructure. The increased impervious land cover and modified drainage patterns have altered both the intensity and timing/concentration of runoff in localized areas. The watershed is exhibiting the effects of this increased urbanization, including the loss of riparian habitat, the alteration of the stable stream morphology, localized bank erosion, the degradation of water quality, and the loss of aquatic habitat. Further, the potential for continued development is high. 2.2 Restoration Site Site Description Section 1 is a 650-foot reach (542 LF restoration) located adjacent to a picnic/fitness trail that begins approximately 2,700 feet downstream of the County Line. The left bank height approaches five feet and severe erosion is prevalent throughout this reach. Several large trees have fallen into the channel creating obstructions to flow and fitness trail-related structures are also being compromised. Section 2 is an incised reach with high, unstable banks in most areas. Channel degradation has disrupted the proper utilization of the floodplain and accelerated rates of bank erosion are prominent. A sanitary sewer line parallels the left side of the stream riparian belt width throughout the section and encroaches to within 30 feet of the left top-of-bank. Likewise, a housing development occupies the right floodplain position throughout the section, with buildings and parking areas located as close as 20 feet from the top-of-bank. Continued bank erosion could potentially threaten these structures. Bankfull Verification The standard methodology used in natural channel design is based on the ability to select the appropriate bankfull discharge and generate the corresponding bankfull hydraulic geometry from a stable reference system(s). Thus, the determination of bankfull stage is the most critical component of the natural channel design (NCD) process. Bankfull can be defined as "the stage at which channel maintenance is most effective, that is, the discharge at which moving sediment, forming or removing bars, forming or changing bends and meanders, and generally doing work that results in the average morphologic characteristics of the channels," (Dunne and Leopold, 1978). Several characteristics that commonly indicate the bankfull stage include: incipient point of flooding, breaks in slope, changes in vegetation, highest depositional features (i.e. point bars), and highest scour line. The identification of bankfull stage, in general, let alone in a degraded system can be problematic. Therefore, verification measures must be taken to ensure the correct identification of the bankfull stage. The three methods used to verify bankfull stage at Richland Creek were regional hydraulic geometry relationships (regional curves), a pressure transducer /data logger combination gauge that monitored actual water level in Richland Creek throughout the study period, and a hydrology/hydraulics model to evaluate flow and sediment transport. Regional curves are typically utilized in ungauged areas to approximate bankfull discharge, area, width, and depth as a function of drainage area based on inter-related variables from other similar streams in the same hydrophysiographic province. Regional curves and corresponding equations from "Bankfull Hydraulic Geometry Relationships for North Carolina Streams" (Harman et al., 1999) were used to approximate bankfull in the project reach. Based on the regional curves, a bankfull discharge and cross-sectional area of 310 ft3/s and 69 ftz would be anticipated in Section 1. Section 2 would discharge 370 ft3/s through 82 ft2 based on a drainage area of 7.2 square miles. Stream stage data (water levels) were collected in Section 2. Data was collected for five months (June through October) and water levels were correlated to an estimated discharge using a rating curve generated for the gauged section. Three significant flow events occurred during the monitoring period. On August 30`x, Richland Creek in the vicinity of the gauge was discharging approximately 309 ft3/s. August 13"' and June 8"' experienced flows exceeding 185 and 155 ft3/s, respectively. The stage data collected during this period is useful in supporting/validating the bankfull identification from field indicators. Refer to Appendix 1 for a summary of the collected hydrology data. Information from the regional curves and from the hydrologic monitoring was used in conjunction with the Hydrologic Engineering Center River Analysis System (HEC-RAS) software to refine the bankfull determinations. The model allows for analysis of one-dimensional (1-D) steady state flow by solving for the energy equation. The approximate discharges calculated using the Manning open channel flow equation were run through the modeled reaches. The outputs corresponded well with the field indicators and allowed for minor adjustments to the bankfull "call" and to the subsequent calculations of the existing morphological variables. Existing Stream Characteristics A Rosgen Level III assessment of Richland Creek was conducted in May-July 2004. Representative channel cross-sections were surveyed at four locations in Richland Creek (two in each of the two sections). Summary data from the existing conditions survey is included in the morphological design criteria table (Table 1) presented later in this document. Photo- documentation is included in Appendix 2. Stability Assessment The Rosgen Level III assessment is also referred to as the "stream state or condition," stage in the hierarchy of river inventory (Rosgen, 1996). This technique assesses the stability of streams by investigating various parameters such as channel dimension and pattern (W/D51~ compared with W~reference~ Meander Width Ratio), lateral stability (BEHI), vertical stability (Bank Height Ratio), sediment supply and transport, and evolution scenario. The stability assessment illustrated that the channel condition varies locally in Richland Creek with some reaches experiencing significant disturbance and others moving towards a state of dynamic equilibrium. Section 1 is experiencing active bank erosion throughout the reach. Bank height ratios ranging from 1.3 to 1.7 indicate unstable bed conditions. The BEHI rated as high with the scores increasing in the near bank region adjacent to the gazebo in the lower portion of the reach. Section 1 appears to be in Stage IV of the channel evolution model (CEM) presented by Simon (1989). Stage IV indicates that the channel is experiencing bed degradation and widening processes as a function of the channel's instability. Section 2 is also experiencing lateral bank erosion for extended reaches. The channel is in the process of enlarging and expanding its belt width in an effort to restore its natural pattern and achieve a state of equilibrium. Several beaver dams have altered the condition of Richland Creek in this section; flattening the slope upstream and inducing scour downstream. These obstructions have also created minor blockages that are influencing the bank stability in the adjacent areas. Overall, many of the stability related issues that are commonly associated with suburban development and a changing hydrologic regime have been documented throughout the Section 2 reach. Constraints The following are a list of documented constraints that were considered in the development of a restoration strategy for Richland Creek in Wake Forest: ^ Presence of a subsurface sewer line that runs parallel and adjacent to the east bank of Richland Creek for the entire length of the Section 2 reach. This line is associated with a 25- foot wide maintained easement corridor. ^ Presence of the Stadium Drive bridge at the downstream limits of Section 2. ^ A vegetated corridor limits access to perform the stream restoration without mechanized clearing. ^ An exercise course occupies the area to the east of Section 1 (efforts to minimize encroachment into this area have been considered). 3.0 REFERENCE REACH ANALYSIS A reference reach is a channel with a stable dimension, pattern, and profile within a particular geomorphic and hydrologic setting. The reference reach is used to develop dimensionless morphological ratios (based on bankfull stage) that can be extrapolated to disturbed/unstable streams to restore a stream of the same type and disposition as the reference stream (Rosgen, 1998). 3.1 Richland Creek Above Section 1 Reach (RCASIR) An upstream reach of Richland Creek located on the west side of the Town of Wake Forest was selected to serve as a reference reach for the restoration of Sections 1 & 2. Richland Creek flows south from its headwaters in Franklin County towards its confluence with the Neuse River (Figure 4). It drains approximately 4.8 square miles of low-density residential, agriculture, and forested lands. This selection was based on: location in the same hydrophysiographic province, same valley morphology, and similar sediment regime as the project reaches. The valley slope is similar to 9 v ~ • /A -__ ~ ~ ~ ~ ~_ ~' ' ~ 1 ` ` ~'` _ - }~ ~ ~~ ~~ ~.,, ~ "~ A - r j :: ~ '1 ~ - 1 \ 1 ~ ~ Wake County JJ ~'~ . ~ ~--~ ~ ,~ 5 +~+ 7 ~ ~ . ( ~ . ~`_ . f Figure 4. Reference Reach -Richland Creek Above Section 1 Reach Richland Creek Above Section 1 Reach 1000 0 1000 Feet Source: USGS Topographical Quadrangles (Grissom, Franklinton) that in Section 1 and 2 (0.45% compared to 0.5% and 0.35% respectively). The sediment distribution is somewhat coarser than the project reaches (d50: 7.1 millimeters compared to 4.3 and 4.7 mm; d84: 15 mm compared to 11 mm and 8 mm), however it is representative of the materials moving through the Richland Creek system. Location in the same drainage (upstream) makes RCAS 1R the most suitable candidate for evaluation of a stable/stabilizing channel under the same conditions that influence the project reaches. Approximately 400 linear feet of Richland Creek were surveyed in August 2004. This reach of Richland Creek was classified as a "C4" channel type. 3.2 Unnamed Tributary to Lake Wheeler (UTLW) UTLW is a third order stream located on the south side of Raleigh that flows southward into Lake Wheeler (Figure 5). It drains approximately 0.3 square miles of predominantly low-density residential land use with the remaining land consisting primarily of forest. The selection of this reach was based on: location in the same hydrophysiographic province, similar valley type, and similar sediment regime as the project reaches. The valley slope is slightly steeper than the restoration reaches (0.6% compared to 0.5% and 0.35%) and the sediment distribution is coarser with a median grain size of 16 millimeters. Local topography is characterized by rolling hills, which is consistent with land forms found at Richland Creek and throughout the Piedmont province and the reference reach and project sites are both located in the Raleigh Belt. UTLW was surveyed to provide supplemental information to facilitate the design of Richland Creek. Approximately 250 linear feet of the UTLW were surveyed in August 2004. UTLW was classified a "C4" channel type. Summary data from the UTLW reference reach survey are included in the morphological criteria table (Table 1). 4.0 NATURAL CHANNEL DESIGN 4.1 Design Methodology Different scenarios require different approaches with respect to stream restoration design in degraded systems. In "A Geomorphological Approach to Restoration of Incised Rivers (Rosgen, 1997)," four priority levels of restoration are described with accompanying explanations of channel type conversion and the advantages and disadvantages of each method. Refer to Figure 6. 4.2 Richland Creek Restoration Design The restoration of Richland Creek is based on Priority Level 2 and Priority Level 4 approaches. The design proposes constructing a meandering channel at the existing grade with a new floodplain at a lower elevation. Bank stabilization using natural materials, vegetation, and boulders will be performed following the grading of these reaches. Refer to Appendix 3 (Restoration Design Plan Set) for the proposed channel pattern and profiles. The design bankfull stage will equal the floodplain elevation of the new channel (bank height ratio = 1.0). The channel dimensions reflect slightly wider and shallower cross-sections, as the 11 ~,'',--_~ _ -~~~1~~ , f ~l~ tr ~ `~'} r1 {k i r ` 1 '\\~ ^ rJ~~ t ~, dvertJowz w,a v EtFV ?82 ~~ Y7YI ~ _~ __ `~~~ ~~ ~~ ~ ~ _._._` _--- ~' l~ ~`~'~;~ y -- _ t ~ ~~ ~~~~, `. ,`may-~ ~ , 1 ~~~ r ~~ ~ ~ 1 ~'(!ii-i-~ ~ ~ ~ ~ j' ~ ~~-~ %~ ~. r~ ~ ,~~,. r^? .; ,,.~ ~_~.~ Wake County + ~ ,, ~l! ~ w~~~~ ~~t'1``~~ .i';~~ ~ /~(~~~ ~L--r"•~~1 ~ 1~~~'~,ti~r/, ~y'~~~- I l_ ~ it U^-~.l r I Figure 5. Reference Reach -Unnamed Tributary to Lake Wheeler Unnamed Tributary to Lake Wheeler 2000 0 2000 Feet Source: USGS Topographical Quadrangle -Lake Wheeler Table 1. Morphological Design Criteria, Richland Creek Stream Restoration Reference: Reference: Existing Existing Richland UT to Lake Propose Propose CLASSIFICATIO Channel Channel Creek Wheeler d d N DATA Seaton Section Above Channel Channel T 2 Section 1 Section 1 Section 2 Rosgen Stream Type C/E4 Inc. E4 C4 C4 C4 C4 Drainage Area (aq mi) 5.6 7.2 4.8 0.3 5.6 7.2 Bankfull Width (W ~~) 26-28 25 28-32 12 3-13 5 28 5 32 (ft) . . . Bankfull Mean Depth 2 4-2 5 3.1 2 3-2 4 1 0-1 1 2 3 2 5 (dbx~) (n) . . . . . . Bankfull Cross Sectional area (Aa,~) (sf) 64-67 78 67-75 13-14 65 80 Width/depth Ratio 10.6-11.52 8.1 11.7-13 9 11 2-13 5 12-13 12.13 (W bk/dbki) . . . Maximum Depth (dmbk/) 3.5-4.2 4.1 3 75 1 6-1 8 3 7 4 0 (n) . . . . . Widlh of flood prone >100' >100' >100' >50' >100 >100 area (W~a) (n) Entrenchment Ratio >3.0' >3.0' > 3.0' >3 0' >3 0 >3 0 (ER) . . . Water Surtaca Slope (S) (fUn) 0.0045 0.003 0.004 0.005 0.0043 0.003 Sinuosity (stream 1 1 1 0-1 1 1 1 1 2 1 15 1 15 Ian th/veils len th K . . . RIMENSlON DATA Pool Da th n 2.8 3.1 2.9 1.2-1.3 2.8 3.0 Riffle De th n 2.4-2.5 3.1 2.3-2.4 1.0-1.1 2.3 2.5 Pool Width ft 28 27 26-35 10.5-12.0 31.4 35 Riffle Width n 26-28 25 28-32 12.3-13.5 28.5 32 PooIXS Area sf 70 80 70-75 14-15 78 95 Riffle XS Area sf 64-67 78 67-75 13-14 65 80 Pool depth/mean riffle 1 1-i 2 1 0 1 2-1 3 1 1-1 3 1 2 1 2 de th . . . . . . Pool width/riffle width 1.0-1.1 1.1 0.9.1.1 0.8-1.0 1.1 1.1 Pool area/ritfle area 1.0-1.1 1.0 0.9-1.1 1.0-1.2 1.2 1.2 Max ool de th/d 1.9-2.0 1.6 1.9-2.0 2.0-2.4 2.2 5.1 2.2 5.5 Low bank heighUmax bankfull de th 1 3-1.7 1.3 1.0-1.2 1.0-1.2 1.0 1.0 Mean Bankfull Velocity V f s q 7.4.9 4.6 3.6-5.0 3.0 4.9 5.0 Bankfull Discharge ((l) 310-320 360 260-270 35-42 320 400 ds PATTERN DATA Meanderlen th L ft 72-237 97-165" 110.200 33-74 143-285 160-320 Radius of curvature (Rd) " n 30.120 30-60 30-70 17-20 57-86 64-96 Belt width ft 110 220 300 50 200 225 Meander width ratio 3.9-4.2 8.8 9.3-10.7 3.7-4.1 7.0 7.0 w, Radius of curvaturelbankfull width 1.1-4.3 1.2-2.4 1.0.2.5 1.3-1.6 2.0-3.0 2.0-3.0 Meander length/bankfull width 2.6-8.5 3.9-6.6 3.5.7.1 2.4-6.0 5.0.10.0 5.0-10.0 PROFILE DATA Valle sloe 0.005 0.0035 0.0045 0.006 0.005 0.0035 Average water surface slo e 0.0045 0.003 0.004 0.005 0.0043 0.003 Riffle slope 0.007- 0.015 0.006 0.005-0.009 0.006-0.02 0.005-0.012 0.004-0.009 Pool slope 0.000- 0.000- 0 000- 0.001 0.002 0.000-0.0025 0.000-0.001 . 0.0012 0.000.0.001 Pool to ools acin 63-93 21-69 25-90 15-84 29-177 23-200 Pool len th 11-28 10-33 5-25 9-20 29-57 32-64 Riffle slope/avg water surface slo e 1.6-3.3. 2.0 1.3-2.3 1.2-4.0 1.2-3.0 1.2-3.0 Pool slope/avg water surtace slo e 0.0-0.2 0.0-0.7 0.0-0.6 0.0-0.2 0.0-0.3 0.0-0.3 Run slope/avg water surface slo e 0.9-1.6 0.7-1.5 0.7-1.2 0.5-0.7 0.5-1.2 0.5-1.2 Run de th/d 1.0-1.1 1.0-1.1 1.0-1.1 1.0-1.1 1.1 1.1 Pool length/bankfull width 0.4-1.1 0.4-1.3 0.2-0.9 0.7-1.8 1.0-2.0 1.0-2.0 Pool to pool s acin /bankfull width 2.3-3.6 0.8-2.8 0.8-3.0 1.1-6.2 10.-6.2 1.0-6.2 * Approximations based upon limited morphological survey ** Pattern measurements are representative of the 500 ft immediately upstream of Stadium Dr. only (the remainder of the section has been altered and does not exhibit natural characteristics). Fisure 6. Priority Levels of Incised River Restoration DESCRIPTION METHODS ADVANTAGES DISADVANTAGES PRIORITY 1 Convert Gand/or F stream Re-establish channel on Re-establishment of 1) Floodplain re- types to C or E at previous previous floodplain using floodplain and stable establishment could cause elevation with floodplain. relic channel or construction channel: flood damage to urban, of new bankfull discharge 1) reduces bank height and agricultural, and industrial channel. Design new streambank erosion, development. channel for dimension, 2) reduces land loss, 2) Downstream end of pattern, and profile 3) raises water table, project could require grade characteristic of stable form. 4) decreases sediment, control from new to previous Fill in existing incised 5) improves aquatic and channel to prevent head- channel or with terrestrial habitats, cutting. discontinuous oxbow lakes 6) improves land level with new floodplain productivity, and elevation. 7) improves aesthetics. PRIORITY 2 Convert Fand/or G stream If belt width provides for the 1) Decreases bank height and 1) Does not raise water table types to C or E. minimum meander width streambank erosion, back to previous elevation. Re-establishment of ratio for C or E stream types, 2) Allows for riparian 2) Shear stress and velocity floodplain at existing level or construct channel in bed of vegetation to help stabilize higher during flood due to higher, but not at original existing channel, convert banks, narrower floodplain. level. existing bed to new 3) Establishes floodplain to 3) Upper banks need to be floodplain. If belt width is help take stress off of sloped and stabilized to too narrow, excavate channel during flood, reduce erosion during flood. streambank halls. End-haul 4) Improves aquatic habitat, material or place in 5) Prevents wide-scale streambed to raise bed flooding of original land elevation and create new surface, floodplain in the deposition. 6) Reduces sediment, 7) Downstream grade transition for grade control is easier. PRIORITY 3 Convert to a new stream type Excavation of channel to 1) Reduces the amount of 1) High cost of materials for without an active floodplain, change stream type involves land needed to return the bed and streambank but containing a floodprone establishing proper river to a stable form. stabilization. area. Convert G to B stream dimension, pattern, and 2) Developments next to 2) Does not create the type, or F to Bc. profile. To convert a G to B river need not be relocated diversity of aquatic habitat. stream involves an increase due to flooding potential. 3) Does not raise water table in width/depth and 3) Decreases flood stage for to previous levels. entrenchment ratio, shaping same magnitude flood. upper slopes and stabilizing 4) Improves aquatic habitat. both bed and banks. A conversion from F to Bc stream type involves a decrease in width/depth ratio and an increase in entrenchment ratio. PRIORITY 4 Stabilize channel in place. Along list of stabilization 1) Excavation volumes are 1) High cost for stabilization. materials and methods have reduced. 2) High risk due to excessive been used to decrease 2) Land needed for shear stress and velocity. streambed and streambank restoration is minimal. 3) Limited aquatic habitat erosion, including concrete, depending on nature of gabions, boulders, and stabilization methods used. bioengineering methods. source: Kosgen, 1997, "A Cieomorphological Approach to Restoration of Incised Rivers". width-depth ratio increases from 8 - 11.5 to 12 - 13. The proposed bankfull widths are 28.5 and 32 feet respectively (Section 1 & 2) and the mean /maximum depths are 2.3 / 3.7 and 2.5 / 4.0 feet (Appendix 3 -Details: Typical Cross-Sections). The range of dimensionless ratios for meander length (5.0 - 10.0) and radius of curvature (2.0 - 3.0) have been marginally increased resulting in longer meander lengths and higher meander radii of curvature. This shift is necessary to accommodate for the absence of immediate mature vegetation to stabilize stream banks. The re-establishment of a riffle-pool sequence and appropriate pool spacing with respect to the channel pattern have been addressed in the profiling of the design channel (Appendix 3). Refer to Table 1 for detailed morphological criteria. In-stream structures have also been incorporated to assist with the immediate stabilization of the restored channel. These structures are designed to reduce bank erosion and the influence of secondary circulation in the near-bank region of stream bends. The structures further promote efficient sediment transport and produce/enhance in-stream habitat. Cross-vanes will serve as grade control in the restored channel. Appendix 3 (Details: Stream Restoration) depicts design details for the in-stream structures. 4.3 Riparian Buffers The Richland Creek floodplain in the project reach is predominantly forested with hardwood species (Refer to Section 2.1). The restoration project will generally utilize the same belt width as the existing channel, however some areas will require clearing to achieve the appropriate pattern outlined in the design criteria. Several large trees that have fallen or are at risk of falling due to bank and bed erosion of the existing channel will also be removed. The cleared areas will be re-vegetated with native woody and herbaceous plant materials. Following the re-vegetation, riparian buffers associated with the Richland Creek restoration will extend over fifty (50) feet on both sides of the stream for the majority of the project reach. The re-vegetated zone will consist of the following trees and shrubs: American sycamore, green ash, river birch, tulip tree, American elm, slippery elm (Ulmus rubra), silky dogwood (Cornus amomum), witch hazel (Hamamelis virginiana) and box elder. Herbaceous vegetation shall consist of a native grass mix that may include: bluestem (Andropogon glomeratus), deertongue (Panicum clandestinum), orchardgrass (Dactylis glomerata), switchgrass (panicum virgatum), and Virginia wildrye (Elymus virginicus). Rye grain (Secale cereale) and/or brown top millet (Pennisetum glaucum) will be used for temporary stabilization. In addition to the native seed mix and stabilization seeding, live stakes shall be installed to assist in stabilizing the stream banks. The following species may be used for live staking: black willow (Salix nigra), elderberry (Sambucus canadensis), silky willow (Salix sericea), and silky dogwood. Four hundred thirty-six (436) trees per acre (based on a 10' X 10' plant spacing) will be planted to achieve a mature survivability of three hundred twenty (320) trees per acre in the riparian zone (DENR, 2001). Woody vegetation shall be installed between November and March when the plants are dormant. 5.0 SEDIMENT TRANSPORT A stable channel is able to move the sediment supplied by its watershed without aggrading or degrading. The restored channels must be competent and have sufficient transport capacity. Competency is the channel's ability to move particles of a certain size. Capacity is the channel's 15 ability to move a specific volume of sediment (sediment discharge). Sediment discharge is the amount of sediment moving through a cross section over a specified period of time (lbs/s). KCI utilized the surface-based transport model (SBTM) developed by Wilcock and Crowe (Wilcock & Crowe, 2003) to analyze the sediment transport in the Richland Creek Reference Reach and subsequently in the designed Richland Creek channel (Sections 1 & 2). In basic terms, given the bed surface grain-size distribution and the bed shear velocity, the SBTM calculates the bedload transport rate and the bedload grain-size distribution. Using the hydraulics model, one can predict the shear velocity and discharge characteristics that will provide the necessary sediment transport capacity. By making the sediment transport and discharge dimensionless, this analysis can be scaled to another section of the channel, separate from the reference reach. In this case, it was scaled to the design sections. In the Richland Creek Reference Reach, the approximate bankfull depth was 3.7 feet (1.1 m). The shear velocity associated with this discharge based on the hydraulics model was 0.17 meters per second (m/s). This shear velocity corresponded to a dimensionless sediment transport rate (qT*) of 250,000 (2.5E-OS). A qT* value of 2.5E-OS intersects with a dimensionless water discharge (qw*) of approximately 1,500 for the Section 1 design slope (0.004) on the Richland Creek River State Diagram (Figure 7). The proposed design channel will discharge approximately 220 ft3/s over the area subject to bedload transport. The water discharge (qw) for this event based on the Manning-Strickler Resistance Equation is 3.100, which correlates to a qw* value of 1,744 (0 = 16.3%). A qT* value of 2.5E-OS intersects with a dimensionless water discharge (qw*) of approximately 2,000 for the Section 2 design slope (0.003) on Figure 7. The proposed effective design discharge (over the bedload portion of the channel) is approximately 300 ft3/s. The water discharge (qW) for this event is 3.360, which correlates to a qw* value of 1,891 (0 = 5.5%). 6.0 FLOODING ANALYSIS Richland Creek is located in a Federal Emergency Management Agency (FEMA) 100-Year Floodzone. As such, any modifications to the stream that would result in the increase of the 100- year flood elevation would require a Conditional Letter of Map Revision. It is the intent of the restoration design to maintain the 100-year flood elevation at the current level following restoration. The North Carolina Flood Mapping Program provided an existing conditions HEC-RAS (River Analysis System) model. The model parameters were reviewed to verify that the conditions represented a benchmark hydraulic condition that could be compared to post-restoration conditions. The existing conditions model will be revised to reflect changes to the channel and floodplain as a result of the restoration. A proposed hydrology and hydraulics (H&H) summary will be submitted with a letter indicating that an increase in the 100-year flood elevation is not anticipated (No-Rise Certification). 7.0 MONITORING AND EVALUATION Monitoring shall consist of the collection and analysis of stream stability data and a qualitative assessment of riparian/stream bank vegetation survivability, to assist in the evaluation of the project in meeting established restoration objectives. 16 Figure 7. 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I I I I l i 1.00E-01 1.00E-02 1.00E-03 1.00E-04 «r a 1.00E-OS 1.00E-06 1.00E-07 1.00E-08 7.1 Stream Monitoring Dimension -Permanent cross-sections will be established along the restored reaches at intervals equal to one cross-section every twenty (20) bankfull-widths lengths and will be used to evaluate stream dimension stability. The permanent cross-sections will be evenly divided between riffle and pool bed features. Permanent monuments will be established at the left and right extents of each cross-section by either conventional survey or GPS. The cross-section surveys shall provide a detailed measurement of the stream and banks, to include points on the adjacent floodplain, at the top of bank, bankfull, at all breaks in slope, and the thalweg. Subsequently, width/depth ratios, entrenchment ratios and low bank height ratios will be calculated for each cross-section. Profile -Longitudinal profiles, each covering twenty (20) bankfull-width lengths, will be established at locations that are representative of restored channel conditions. The beginning and ending points of each measured section will be permanently monumented. Average water surface, pool, and riffle slopes, as well as pool-to-pool spacing will be calculated. Pattern -Measurements of the restored channel pattern, to include belt width, meander length, and radius of curvature will be collected within the same sections surveyed for the longitudinal profiles. Calculations will be made for meander width ratio, radius of curvature/bankfull width ratio, and meander length/bankfull width ratio. Bed Materials -Pebble counts will be conducted at each riffle cross-section, as well as across the overall study reach (based upon percentage of riffles and pools) for the purpose of classification and to evaluate sediment transport. Hydraulics -The success of restoring the bankfull return period (once every 1.4 to 1.7 years) will be evaluated using two (2) automatic stream monitoring gauges to record continuous stream depth readings. One gauge will be placed at or near the upstream limits of the project reach. The other will be placed at or near the downstream limits. 7.2 Vegetation Monitoring A qualitative vegetation assessment will be performed following the first growing season to identify any areas that are not fulfilling the stabilization needs of the channel and/or the re- vegetation standards of the riparian areas within the conservation easement. Any areas that are considered to be delinquent will be replanted under the warranty of the contract. 18 REFERENCES Dunne, T. and L.B. Leopold. 1978. Water in Environmental Planning. New York: W.H. Freeman and Company. Harman, W.A., G.D. Jennings, J.M. Patterson, D.R. Clinton, L.O. Slate, A.G. Jessup, J. R. Everhart, and R.E. Smith, 1999. Bankfull Hydraulic Geometry Relationships for North Carolina Streams. Wildland Hydrology. AWRA Symposium Proceedings. Edited by D.S. Olsen and J.P. Potyondy. American Water Resources Association. June 30 -July 2, 1999. Bozeman, MT. Harrelson, C.C., C.L. Rawlins, and J.P. Potyondy. 1994. Stream Channel Reference Sites: An Illustrated Guide to Field Technique. General Technical Report RM-245. USDA Forest Service, Rocky Mountain Forest and Range Experiment Station, Fort Collins, CO. NCDENR. 2001. "Guidelines for Riparian Buffer Restoration." Division of Water Quality, Wetlands Restoration Program, Raleigh, NC. NCDENR. "Water Quality Stream Classification for Streams in North Carolina." Water Quality Section. http://h2o.enr.state.nc.us/bims/reports/basinsandwaterbodies (September, 2002). NCGS. 1985. Geologic Map of North Carolina North Carolina State Data Center (NCSDC). 2001. Census 2000 Summary File for Town of Wake Forest, North Carolina. (Internet accessed via: www.census.state.nc.us). Rosgen, D.L. 1996. Applied River Morphology. Wildland Hydrology Books, Pagosa Springs, CO. Rosgen, D.L. 1997. A geomorphological approach to restoration of incised rivers. In: Wang, S.S.Y., E.J. Langendoen, and F.D. Shields, Jr. (Eds.). Proceedings of the Conference on Management of Landscapes Disturbed by Channel Incision. pp. 12-22. Rosgen, D.L. 1998. The Reference Reach - a Blueprint for Natural Channel Design. Presented at ASCE Conference, Denver, CO -June, 1998. Schafale, M.P. and A.S. Weakley. 1990. Classification of the Natural Communities of North Carolina, 3'd Approximation. North Carolina Natural Heritage Program, NCDEHNR, Division of Parks and Recreation. Raleigh, NC. Simon, A. 1989. A model of channel response in disturbed alluvial channels. Earth Surface Processes and Landforms. 14(1): 11-26. USDA. 1970. Soil Survey for Wake County, North Carolina. Soil Conservation Service. Wilcock, P., and J. Crowe. 2003. "A Surface-Based Transport Model for Sand and Gravel. ASCE Journal of Hydraulic Engineering, ASCE, 129(2), pp 120-128. 19 Appendix 1-Richland Creek Hydrograph Richland Creek Hydrograph 6/1/2004 to 9/1/2004 o.oo -~- Aug-04 Richland Creek Hydrograph 9/01/2004 to 10/21/2004 Sep-04 Date Oct-04 ~_ Appendix 2 -Site Photograph Documentation a Richland Creek Stream Restoration Photograph Documentation r uviug~ uNu ^. ~ ypicai u~uuwg uaurc au~acecu to uie exercise/fitness area in Section I. Photograph 4. Typical channel conditions in the upstream portion of Section 2. Longitudinal survey. r uuwg. ayu c. uu~mu~u ~uaa~ w ~ecuun ~; upstream or the gazebo in the background (left). ruuwg~ayu ~. i.~u»-acuiuu aw vcy ui puu~ m xcuuu t. . .wwg~aeu ~. .ytncai uauuwK uaurc wnu wss u~ uanrc vegetation, near downstream limits of Section I . ... .og. apu v. ucavc~ uu~u uu~uw~wucm iucatcu w Section 2 reach. S Photograph 7. Typical eroding bank. Condition persists throughout Section 2 reach. Photograph 10. Example of one of the small tributary inflows that will be stabilized as part of the restoration project. Photograph 8. Typical over-widened cross-section; Section 2. Photograph 11. Upstream view of over-wide cross-section invncdiatcly above the Stadium Drive Bridge. Photograph 9. Looking upstream in lower portion of Section 2. Note the beaver dam in the foreground and the eroding bank in the background (left). Photograph 12. Downstream view of the typical cross- scction and run-pool transition i^ the RCASI Rclcrcncc Reach. Photograph 13. Hydrologic monitoring gauge used to study flow regime and verify bankfull in Section 2. Photograph 14. Typical bar sampled for use in sediment transport analysis. .~ Appendix 3 -Restoration Design Plan Set