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HomeMy WebLinkAbout20011231 All Versions_R-2248D_Site 19 Review and Remedial Action_201401061 SITE REVIEW AND RECOMMENDATIONS FOR REMEDIAL ACTION R-2248D – CHARLOTTE OUTER LOOP TRIBUTARY TO DIXON BRANCH (SITE 19) ON-SITE STREAM MITIGATION MECKLENBURG COUNTY, NORTH CAROLINA TIP NUMBER: R-2248D Prepared for NORTH CAROLINA DEPARTMENT OF TRANSPORTATION PROJECT DEVELOPMENT AND ENVIRONMENTAL ANALYSIS BRANCH RALEIGH, NORTH CAROLINA DECEMBER 2014 2 TABLE OF CONTENTS 1.0 PROJECT BACKGROUND .......................................................................................... 3 2.0 PROJECT PURPOSE AND OBJECTIVE(S) ............................................................... 3 3.0 FIELD INVESTIGATION TECHNIQUES .................................................................. 3 4.0 FIELD WORK DATA AND RESULTS ........................................................................ 4 5.0 OPINION OF CHANNEL STABILITY AND EVOLUTION ...................................... 5 6.0 MAINTENANCE AND REPAIR RECOMMENDATIONS ........................................ 5 7.0 REFERENCES ............................................................................................................... 6 FIGURES FIGURE 1 SITE ASSESSMENT FIGURE FIGURE 2 CONCEPTUAL REPAIR PLAN APPENDICES APPENDIX A BACKGOUND DATA/FILE REVIEW APPENDIX B GEOMORPHIC SURVEY DATA, BEHI, AND NBS APPENDIX C PHOTO PAGE 3 1.0 PROJECT BACKGROUND The area of investigation included in this report is the North Carolina Department of Transportation’s (NCDOT) on-site mitigation project located west of Statesville Road (HWY 21) and east of I-77 northbound, just north of the T-intersection of HWY 21 and Twin Lakes Parkway. The NCDOT constructed this as an on-site mitigation project in May 2008. The specific area of investigation is identified as “Site 19” as specified in the United State Corp of Engineers (USACE) 404 Individual Permit (Action ID #200131321) and North Carolina Division of Water Resources (DWR; formerly the Division of Water Quality) Certification (WQC #011231). Based on the design plans provided by NCDOT, the stream alignment is 600+ feet and is consistent with the original design. The site has been monitored by NCDOT staff for the past 7 years. As documented in the last monitoring report provided by NCDOT, the following modifications and repairs have occurred since construction was completed in 2005: ·May 2010 – The area downstream of culvert (access road to build board) was repaired with a combination of boulders and bank grading. ·2013-2014 – Two applications of herbicide were applied to remove the lespedeza noted during the summer 2012 agency meeting. ·March 2014 – The left stream bank was live staked with black willow and silky dogwood where dead or missing stakes were noted. Additional supplemental planting on the left bank and floodplain included willow oak, sycamore, river birch, and green ash. 2.0 PROJECT PURPOSE AND OBJECTIVE(S) The purpose of this project scope was to: ·Provide a detailed qualitative and quantitative site review, including a geomorphic survey, near bank stress (NBS), bank erosion hazard index (BEHI), and corresponding sediment load ·Determine if this localized instability is systemic and could be an indication of a larger problem ·Determine the channel evolution state (i.e., is the channel moving towards stability or instability) ·Provide maintenance and repair recommendations if they are necessary The objective of this project is to better understand the sites function and stability and to collect limited quantitative data on the stream’s geomorphic conditions to inform NCDOT so they can develop a course of action to allow the project to be closed out by the resource agencies. 3.0 FIELD INVESTIGATION TECHNIQUES Kimley-Horn staff performed two field reviews in October 2014. During the field visits, a general qualitative review of the site’s hydraulic and geomorphic functions was completed. The review evaluated the overall channel stability, in-stream structures, and riparian buffer. In addition to this qualitative evaluation, a quantitative evaluation was performed. This evaluation included a detailed geomorphic survey of the site and BEHI and NBS data collection. The geomorphic survey included a representative longitudinal profile from the beginning of the project to the culvert crossing and two representative cross sections. The longitudinal profile data was collected to assess the channel’s floodplain connectivity, incision, and depth variability (i.e., riffle-pool variability). The two cross sections provided data on Rosgen stream type, width-to-depth ratios, bankfull cross-sectional area, and width of available floodplain. The cross sections were chosen to represent one riffle and one pool. The representative longitudinal profile and cross section locations are shown in Figure 1. 4 4.0 FIELD WORK DATA AND RESULTS See Figure 1 for a graphical representation of observed field conditions and location of geomorphic cross sections. See Appendix B for geomorphic survey data (cross sections, profile, and stream classifications). Left and right sides/banks are referenced as if looking downstream (south) in the summary below: General Site Facts: ·Drainage Area = 0.42 square miles ·Study stream length = 605 feet stream and 40 feet of culvert ·Valley length = ~570 feet Qualitative Site Review: ·A bench appears to have developed at the bankfull elevation. ·The stream banks appear stable except for the local areas of erosion in the two outer meander bends noted in Figure 2. o The local erosion in the meander bends appears to be from poor structure geometry and/or a concentration of overland flow as it flows from the top of the bank down to the channel. ·Overall, the stream riparian buffer is continuous with a good mix of woody (trees and shrubs) and herbaceous species. ·The bed is comprised mostly of fine sand and silt with some imported rock (rip-rap) that was placed or washed into a few riffles. ·The channel appears to have depth variability in the reach with a variety of pools, riffles, runs, and glides. Quantitative Geomorphic Assessment: ·Stream is classified as a stable stream type (Rosgen E). ·Average stream slope = 0.007 feet/feet ·Sinuosity = ~1.12 ·Width of flood prone area = 21 to 32 feet (Entrenchment Ration = 2.1-3.7) ·Bankfull Area = 5 square feet in the relatively stable riffle (this is less than NC rural piedmont regional curve value) o This low value indicates that the stream is frequently accessing its floodplain. o These smaller channels are typical of small streams with low upstream sediment sources (i.e., designed as more of a threshold channel than an active transport system). ·Bankfull Area = 32 square feet in the unstable pool area o This location is a blow area at a failed rock vane and is six times the upstream bankfull area. ·Width-to-Depth Ratio = 6.0 (in riffle) ·Pool to Pool Spacing (from profile) = 50 to 100 feet (i.e., 9-18 times Bankfull Width) ·Pool-to-Pool Spacing (from plan, i.e., in the meander bends) = 80 to 90 feet ·The length of bank with high or vary high erosion (based on BEHI and NBS) = 15-20% (~200 feet) – see Figure 1. 5 5.0 OPINION OF CHANNEL STABILITY AND EVOLUTION Based on the above data, the overall channel reach is relatively stable with the exception of two outer meanders as shown in Figures 1 and 2. The stable areas (shown in green on Figure 1) are providing the following functions: ·Hydraulics o A multi-stage channel that includes low flow, inner berm, and bankfull bench is providing flood flow access to overbank areas, which reduces shear stress and velocity. ·Geomorphology o The sinuosity is within typical ranges. o The average slope(s) of the features and overall reach is typical for piedmont streams in Mecklenburg County. o Good depth variability (i.e., pools and riffles) o Good low flow slope variability (i.e., steeper riffles and flat pools) o Good riparian buffer (density and diversity) The less stable areas (shown in yellow, orange, and red in Figure 1) have the following functional deficiencies: ·Hydraulics o The high bank on outside of meander reducing floodplain access and creating higher shear stress. o The failed hydraulic structures (rock vanes) deflecting flow into the bank instead of away from it. The cause of this failure appears to be the improper vertical slope (too steep) and horizontal angle. ·Geomorphology o The cross-sectional area is over-wide where the vanes have failed and the bank has eroded. The bank erosion is increasing sediment supply downstream. o The bank slope and bank height on the outer meander prevents rooting depth and vegetation cover that would offer bank protection and provide long term stability. Based on the above data, it is our professional opinion that these areas of instability should be repaired to prevent the failures from moving upstream or downstream into the more stable sections. The remainder of the site is reaching its dynamic equilibrium and should be protected. 6.0 MAINTENANCE AND REPAIR RECOMMENDATIONS A conceptual repair plan has been prepared and presented in Figure 2. The conceptual repair plan proposes rebuilding two single arm rock vanes to include the appropriate geometry. The repair plan also proposes reshaping the channel geometry at the two eroded pool locations by sloping back the outer bank (left bank). The proposed slope at the outer meanders is 3:1 with a transition area in between (i.e., half a meander length). A native seed mix, soil amendments, straw, and coir fiber matting should be applied to all of the disturbed areas. Live stakes and bare roots should also be planted in the disturbed areas during the appropriate season. The live stakes should be installed on 3-foot centers and the bare roots should be installed on 8-foot centers in a randomized pattern. 6 7.0 REFERENCES Rosgen, D.L. 1996. Applied River Morphology. Wildland Hydrology Books. Pagosa Springs, CO. Rosgen, D.L. 1998. The Reference Reach-a Blueprint for Natural Channel Design. Draft Presented at ASCE Conference on River Restoration. Denver, CO, March, 1998. ASCE. Reston, VA. Rosgen, D.L. 2008. River Stability Field Guide. Wildland Hydrology. Fort Collins, CO. Harman, W.R., R. Starr 2011. Natural Channel Design Review Checklist, US Fish and Wildlife Service, Chesapeake Bay Field Office, Annapolis, MD. Leopold, L.B., M.G. Wolman and J.P. Miller. 1964. Fluvial Processes in Geomorphology, W.H Freeman and Company. San Francisco CA. XS 2 X S 1 £¤21 Statesville Rd Twin Lakes Pkwy ± 50 0 50 Feet Legend:Title: F0408020 Feet Figure 1 - Site 19 Assessment Se diment Load (Tons/Yr)0 - 0.5 0.5 - 1.5 1.5 - 3.3 3.3 - 16.0 16.0 - 50.0 Localize d Blow-Ou t due tostructure failure and poor geometry Bench forming along right bank at the bankfull elevation Profile Extents ± 50 0 50Feet Legend:Figure 1 - Concept Repair PlanTitle: F0408020 Feet APPENDIX A STA. 12+20 Y-7 MATCH SHEET NO. 38 S H E E T N O . P R O J E C T R E F E R E N C E N O . E N G I N E E R R O A D W A Y D E S I G N E N G I N E E R H Y D R A U L I C S 4 2 $DATE$$TIME$$FILE$ 4 2 ME T R I C C O N S T . R E V . R / W R E V . 0 5 1 0 R - 2 2 4 8 D F O R D I T C H G R A D E S , S E E P R O F I L E S H E E T S . F O R C H A N N E L D E T A I L , S E E S H E E T N O . 2 - I . F O R D I T C H D E T A I L S , S E E S H E E T S 2 - G & 2 - H . F O R Y - 7 P R O F I L E , S E E S H E E T N O ’ S . 8 9 & 9 0 . R E F E R E N C E : T R A F F I C C O U N T S 2 0 2 5 A D T U S - 2 1 Y - 7 2 0 0 5 A D T 9 6 0 0 5 9 0 0 8 9 0 0 1 5 , 7 0 0 2 2 0 0 4 7 0 0 T W I N L A K E S P A R K W A Y P A V E D S H O U L D E R F A L S E S U M P D I T C H D E T A I L S H E E T 2 - H L E G E N D 1 0 x 2 x 1 d 2 w e i r 1 0 x 2 x 1 d C O N T R O L F E N C E S P E C I A L S E D I M E N T d d C A A 1 0 x 2 x 1 d A d 2 w e i r 1 0 x 2 x 1 d d C DRAINAGE OUTLETS. AND TEMPORARY ROCK SILT CHECKS TYPE-A AT PLACE TEMPORARY ROCK SEDIMENT DAMS TYPE- B NOTE:CONSTRUCTION SHEET 42 EROSION CONTROL FOR CLEARING AND GRUBBING 2 PS .00 .01 .02 .03 .04 .05 .06 .07 .07 .06 .05 .04 .03 .02 7.2 PS P A I N T E D I S L A N D = 3 5 0 . 0 0 0 Y - 7 P I DL c R c eD S = 8 0 k m / h f s L s T s S T L T = 1 1 + 1 8 . 1 6 7 = 7 2 1 ’ 5 9 . 8 " = 9 0 . 0 0 0 = 3 0 . 0 4 7 = 6 0 . 0 5 2 = 0 . 0 7 = 1 1 8 . 1 6 7 = 5 3 . 9 1 9 = 80 km/h T Y P 1 2. 8 5 7 FUTURE T Y P 1 2 .8 5 7 TS 10+00.000 Y-7 1 0 + 0 0 SC 10+90.000 Y-7 1 1 + 0 0 CS 11+43.919 Y-7 1 2 + 0 0 F U T U R E S B L L A N E S PS 1.2 5 PS 10+00 11+00 Y - 7 R = 3 5 0 12+00 POT 9+90.597 Y-7 BEGIN CONSTRUCTION = 2 3 3 3 ’ 3 5 . 3 " ( R T ) 1.2 3.63.63.6 3.6 VAR 0.9 3.6 1.2 4.5 3.6 3.6 1.2 4.5 (TYP)R=3.0 1 3 . 9 3 7 + 7 8 . 2 0 +80 3 . 6 3 . 6 R = 2 2 .5 T Y P R = 7 .5 VAR. BB B B B B 44.050 N7639’45"W 138.228 N7608’55"W B E S S I E G B L A N K E N S H I P ( E T A L ) D B 1 7 8 0 P G 5 7 0 ttt t M A R C S I L V E R M A N D B 3 5 6 2 P G 3 7 2 E XI S T R/ W E XI S T R/ W E XI S T R/ W E XI S T R/ W 8 6 87DB 9478 PG 874 SMITH CORNERS, LLC + 5 5. 9 2 5 +91.463 18.475 (COR-CL) 8 8 S PIPE APROXIMATE LOCATION CBCBXXXXXXXXXXXXXXXX LT LT7.3 m ASPH5.9 m ASPH 550 mm CONC C&G 850 mm CONC C&G 850 mm CONC C&G GR GR{{z z z 1350 CSP 5 0 0 m m C O N C 500 mmCONC 6.7 m CONC HW6.7 m CONC HW 2.9 m CONC HW 2.9 m CONC HW AATWIN LAKES PARKWAY U S 2 1 (2)2.43(H) X 3.07(W) RCBC 150 0 R C P LOCATION APROXIMATE PIPE z z HWY 21 STATESVILLE RD 10.0 m ASPH V A R A S P H O OPP P P P P P P F C F F C C C C S L O P E S T A K E L I N E F C S L O P E S T A K E L I N E F F F F C C C C C C CCCC C C C C CC RETAIN H E A D W A L L 1 3 5 0 R C P J B R E M O V E 375 R C P F A L S E S U M P II 2 G I( D ) +50 375 RCP 2 G I( D ) +20 B E R M D I T C H B E R M D I T C H REMOVE B E R M D I T C H 2 +80 2 G I(D ) 600 RCP 2 G I(B ) 900 RCP 900 RCP 9 0 0 R C P B E R M D IT C H 1500 R C P 3 H E A D W A L L 4 6 + 1 5 R c = 9 . 5 3 9 + 9 8 R c = 9 . 5 4 5 + 8 1 R c = 9 . 5 4 5 + 6 1 R c = 9 . 5 43 +41Rc=9.5 3 2 + 2 5 R c = 9. 5 23.5+68Rc=9.5RETAINRETAINRETAIN 2 T H R O U G H U S E O F L I V E S T A K E S B A N K S T O B E S T A B L I Z E D O F C H A N N E L A L L R A D I I T O C E N T E R E S T . M D D E 1 9 7 m @ 0 . 7 1 % G R A D E 6 . 6 5 m T O P @ 1 . 3 0 % m D E E P 2 . 9 B A S E W / 1 . 5 : 1 S I D E S L O P E N A T U R A L C H A N N E L D E T A I L 2 G I(B ) E S T . 2 3 . 4 M F F E S T . 1 0 M T O N S C L A S S " B " R I P R A P E S T . 5 . 9 M F F E S T . 1 . 8 M T O N S C L A S S " B " R I P R A P RE M O V E HEADWALL REMOVE F A L S E S U M P III 2 E L B O WS 4 5 0 C S P W / S T ’D 8 5 0 .1 0 B D O S 22.5+88R=9.5 4 2.5 + 0 7Rc =9.5 S U M P I II F A L S E 3 8 8 389 3 9 0 3 9 1 3 9 2 3 9 3 3 9 4 3 9 5 3 9 6 S E E D E T A I L 2 K R O O T W A D ( 3 T O T A L ) SEE DETAIL 2K EST. 27 TONS MIN. 0.6m DIA.BOULDERS NATURAL STONE "V" CROSS VANE S E E D E T A I L 2 K E S T . 2 4 T O N S M I N . 0 . 6 m D I A . B O U L D E R S N A T U R A L S T O N E R O C K V A N E S E E D E T A I L 2 K E S T . 2 7 T O N S M I N . 0 . 6 m D I A . B O U L D E R S N A T U R A L S T O N E " V " C R O S S V A N E S E E D E T A I L 2 K E S T . 2 3 T O N S M I N. 0 . 6 m D I A. B O U L D E R S N A T U R A L S T O N E R O C K V A N E SEE DETAIL 2K EST. 31 TONS MIN. 0.6m DIA.BOULDERS NATURAL STONE ROCK VANE S E E D E T A I L 2 K E S T . 8 T O N S M I N . 0 . 6 m D I A . B O U L D E R S N A T U R A L S T O N E R O C K V A N E +20 27.432 +60.000 Y-7(90.00 FT)48.500 +68.000 Y-7(159.12 FT) 7 1 . 0 0 0 + 6 0 . 0 0 0 Y - 7 ( 2 3 2 . 9 4 F T ) 6 7 . 2 0 0 + 9 8 . 0 0 0 Y - 7 ( 2 2 0 . 4 7 F T ) P R O P . R / W 3 0 . 0 0 0 + 8 7 . 3 4 6 Y - 7 ( 9 8 . 4 3 F T ) 3 4 . 0 0 0 + 9 0 . 0 0 0 Y - 7 ( 1 1 1 . 5 5 F T ) 3 6 .0 0 0 + 4 3 .9 1 9 Y - 7 (1 1 8 .1 1 F T ) P R O P . R / W 4 3. 9 2 5 + 4 3. 9 1 9 Y- 7 ( 1 4 4. 1 1 F T ) ( 1 6 6. 4 7 F T ) 5 0. 7 4 0 + 4 3. 9 1 9 Y- 7 P R O P. R/ W Channel Mitigation Monitoring Sheets I, II, III, AND IV Monitoring Data Record Project Title: R-2248D – Charlotte Outer Loop COE Action ID: 200131321 Stream Name: Trib. to Dixon Branch (Site 19) DWQ Number: 011231 City, County and other Location Information: Mecklenburg County, Charlotte Outer Loop, R-2248D Left of Project Station 10+00 Y-7 Date Construction Completed: May 2008 Monitoring Year: ( 6 ) of 5 Ecoregion: 8 digit HUC unit 03050103 USGS Quad Name and Coordinates: Rosgen Classification: Proposed C4 stream type classification Length of Project: 400 ft. Urban or Rural: Urban Watershed Size: Monitoring DATA collected by: M. Green and J. Young Date: 3/11/14 Applicant Information: Name: NCDOT – Roadside Environmental Unit Address: 1425 Rock Quarry Rd, Raleigh, NC 27610 Telephone Number: (919) 861-3772 Email address: mlgreen@ncdot.gov Consultant Information: Name: Address: Telephone Number: Email address: Project Status: Monitoring Level required by COE and DWQ (404 permit/ 401 Cert.): Level 1 The permittee shall perform the following components of Level I monitoring each year for the 5-year monitoring period or through two documented bankfull flow events: Reference photos; plant survival (i.e. identify specific problem areas (missing, stressed, damaged or dead plantings), estimated causes, and proposed/required remedial action);visual inspection of channel stability. Physical measurements of channel stability/morphology will not be required. The permittee shall submit the monitoring reports to the USACE, Raleigh Regulatory Field Office Project Manager, within sixty days after completing the monitoring. If less than two bankfull events occur during the first 5 years, the permittee shall continue monitoring until the second bankfull event is documented. The bankfull events must occur during separate monitoring years. In the event that the required bankfull events do not occur during the five-year monitoring period, the USACE, in consultation with the resource agencies, may determine that further monitoring is not required. It is suggested that all bankfull occurrences be monitored and reported through the required monitoring period. The permittee shall perform and submit photo documentation twice each year (summer and winter) for the 5-year monitoring period, and for any subsequently required monitoring period. Section 1. PHOTO REFERENCE SITES (Monitoring at all levels must complete this section) Total number of reference photo locations at this site: 8 photos were taken from 4 photo point locations Dates reference photos have been taken at this site: 2/23/09, 9/1/09, 3/16/10, 9/28/10, 3/2/11, 9/12/11, 1/25/12, 9/20/12, 1/23/13, 9/17/13, 3/11/14 Individual from whom additional photos can be obtained (name, address, phone): Other Information relative to site photo reference: A site map with photo point locations is attached to this report. If required to complete Level 3 monitoring only stop here; otherwise, complete section 2. Section 2. PLANT SURVIVAL Attach plan sheet indicating reference photos. Identify specific problem areas (missing, stressed, damaged or dead plantings): The left buffer is lacking planted vegetation due to dense areas of lespedeza noted in 2012. Estimated causes, and proposed/required remedial action: An onsite meeting was held on June 5, 2012, between regulatory agencies and NCDOT. Regulatory agencies stated that additional planted species were needed within the buffer. NCDOT completed two herbicide applications on the lespedeza. The left buffer and left streambank was replanted on 3/11/14 with silky dogwood and black willow live stakes and willow oak, sycamore, river birch, and green ash bareroot seedlings. The left streambank was live staked only where missing or dead stakes were noted. ADDITIONAL COMMENTS: If required to complete Level 1 and Level 2 monitoring only stop here; otherwise, complete section 3. Section 3. CHANNEL STABILITY Visual Inspection: The entire stream project as well as each in-stream structure and bank stabilization/revetment structure must be evaluated and problems addressed. Report on the visual inspection of channel stability. Physical measurements of channel stability/morphology will not be required. Include a discussion of any deviations from as-built and an evaluation of the significance of these deviations and whether they are indicative of a stabilizing or destabilizing situation. UT to Dixon Branch (Site 19) stream relocation is stable for the Year 6 Winter evaluation. Some areas of bank scouring still exist upstream of the pipe crossing at Sta. 10+80 Y-7 and Sta. 10+40 Y-7. The areas of bank scouring behind the two j-hooks have filled in with sediment deposition due to bankfull events since the last monitoring visit. NCDOT live staked these areas on 3/11/14 to help promote woody plant growth. The area downstream of the pipe that had extensive erosion was repaired during May 2010 and is highly stable. A bankfull event had occurred since the last monitoring evaluation. NCDOT will continue to monitor channel stability at Site 19. Date 3/11/14 Station 10+80 Y-7 (additional photo) Station 10+40 Y-7 (additional photo) Station Station Number Station Number Structure Type Is water piping through or around structure? Head cut or down cut present? Bank or scour erosion present? Bank scouring on left bank behind J-hook Bank scouring on left bank behind J-hook Other problems noted? Section 4. DEBIT LEDGER The entire UT to Dixon Branch (Site 19) stream mitigation site was used for the R-2248D project to compensate for unavoidable stream impacts. UT to Dixon Branch Site 19 Photo Point #1 (Upstream) Photo Point #1 (Downstream) Photo Point #2 (Upstream) Photo Point #2 (Downstream) Photo Point #3 (Upstream) Photo Point #3 (Downstream) Year 6 Winter – March 2014 UT to Dixon Branch Site 19 Photo Point #4 (Upstream) Photo Point #4 (Downstream) Left bank scouring at end of J-Hook @ Sta. 10+80 Y-7 Left bank scouring at end of J-Hook @ Sta. 10+40 Y-7 Overview Photo of Site 19 Year 6 Winter – March 2014 APPENDIX B Worksheet 2-3. Field form for Level II stream classification (Rosgen, 1996, 2006b). 269 acres 0.42 mi2 Date:10/29/2014 Bankfull WIDTH (Wbkf) WIDTH of the stream channel at bankfull stage elevation, in a riffle section.ft Bankfull DEPTH (dbkf) ft Bankfull X-Section AREA (Abkf) ft2 Width/Depth Ratio (Wbkf / dbkf) Bankfull WIDTH divided by bankfull mean DEPTH, in a riffle section.ft/ft Maximum DEPTH (dmax) ft WIDTH of Flood-Prone Area (Wfpa) ft Entrenchment Ratio (ER) ft/ft Channel Materials (Particle Size Index )D 50 mm Water Surface SLOPE (S) ft/ft Channel SINUOSITY (k) Sinuosity is an index of channel pattern, determined from a ratio of stream length divided by valley length (SL / VL); or estimated from a ratio of valley slope divided by channel slope (Sval / S). NCDOT, Site 19, Reach 1 Sec.&Qtr.: Cross-Section Monuments (Lat./Long.): Stream: Drainage Area: Observers: Twp.&Rge: Location: Basin: 5.7 0.95 Valley Type:JD/JM Channel slope = "rise over run" for a reach approximately 20–30 bankfull channel widths in length, with the "riffle-to-riffle" water surface slope representing the gradient at bankfull stage. 5.4 6.0 2.17 AREA of the stream channel cross-section, at bankfull stage elevation, in a riffle section. Maximum depth of the bankfull channel cross-section, or distance between the bankfull stage and Thalweg elevations, in a riffle section. 1.16 20.93 3.68 0.05 0.00935 Mean DEPTH of the stream channel cross-section, at bankfull stage elevation, in a riffle section (dbkf = Abkf / Wbkf). E Twice maximum DEPTH, or (2 x dmbkf) = the stage/elevation at which flood-prone area WIDTH is determined in a riffle section. The ratio of flood-prone area WIDTH divided by bankfull channel WIDTH (W fpa / Wbkf) (riffle section). The D 50 particle size index represents the median or dominant diameter of channel materials,as sampled proportionately from the channel surface, between the bankfull stage and Thalweg elevations. Cross Section 1 (Riffle) Stream Type See Classification Key (Figure 2-21) Copyright © 2008 Wildland Hydrology River Stability Field Guide page 2-50 Worksheet 2-3. Field form for Level II stream classification (Rosgen, 1996, 2006b). 269 acres 0.42 mi2 Date:10/29/2014 Bankfull WIDTH (Wbkf) WIDTH of the stream channel at bankfull stage elevation, in a riffle section.ft Bankfull DEPTH (dbkf) ft Bankfull X-Section AREA (Abkf) ft2 Width/Depth Ratio (Wbkf / dbkf) Bankfull WIDTH divided by bankfull mean DEPTH, in a riffle section.ft/ft Maximum DEPTH (dmax) ft WIDTH of Flood-Prone Area (Wfpa) ft Entrenchment Ratio (ER) ft/ft Channel Materials (Particle Size Index )D 50 mm Water Surface SLOPE (S) ft/ft Channel SINUOSITY (k) Basin:Drainage Area: Location: Cross-Section Monuments (Lat./Long.): Stream:NCDOT, Site 19, Reach 1 Cross Section 2 (Pool) Twp.&Rge:Sec.&Qtr.: 32.52 Twice maximum DEPTH, or (2 x dmbkf) = the stage/elevation at which flood-prone area WIDTH is determined in a riffle section. Observers:JD/JM Valley Type: 15.8 2.05 Mean DEPTH of the stream channel cross-section, at bankfull stage elevation, in a riffle section (dbkf = Abkf / Wbkf). 32.5 AREA of the stream channel cross-section, at bankfull stage elevation, in a riffle section. 7.7 3.35 Maximum depth of the bankfull channel cross-section, or distance between the bankfull stage and Thalweg elevations, in a riffle section. 1.16 Sinuosity is an index of channel pattern, determined from a ratio of stream length divided by valley length (SL / VL); or estimated from a ratio of valley slope divided by channel slope (Sval / S). E 2.06 The ratio of flood-prone area WIDTH divided by bankfull channel WIDTH (W fpa / Wbkf) (riffle section). 0.05 The D 50 particle size index represents the median or dominant diameter of channel materials,as sampled proportionately from the channel surface, between the bankfull stage and Thalweg elevations. 0.00795 Channel slope = "rise over run" for a reach approximately 20–30 bankfull channel widths in length, with the "riffle-to-riffle" water surface slope representing the gradient at bankfull stage. Stream Type See Classification Key (Figure 2-21) Copyright © 2008 Wildland Hydrology River Stability Field Guide page 2-50 16 CH WS BKF P1 P2 P3 P4 Elevation (ft) Distance along stream (ft) 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 0 50 100 150 200 250 300 350 400 450 500 P1 Best Fit Slope = 0.00700 BKF Best Fit Slope = 0.00986 WS Best Fit Slope = 0.00795 16 riffle Ground Points Bankfull Indicators Water Surface Points Elevation (ft) Horizontal Distance (ft) 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 0 5 10 15 20 25 30 35 40 45 50 Wbkf = 5.69 Dbkf = .95 Abkf = 5.42 16 pool Ground Points Bankfull Indicators Water Surface Points Elevation (ft) Horizontal Distance (ft) 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 0 5 10 15 20 25 30 35 40 45 50 Wbkf = 15.8 Dbkf = 2.05 Abkf = 32.5 Reach 1 100.9734894 BEHI LOW 0 NBS LOW Soil Density (g/cm^3)1.3 BEHI MODERATE NBS MODERATE Tons per Year per Foot 0.172159627 BEHI HIGH NBS HIGH BEHI VERY HIGH NBS VERY HIGH BEHI EXTREME NBS EXTREME 577.6441602 96.3896704 Right Bank Feet Assessed 586.5108514 4.583819041 Erosion (ft/year)Length (ft)Bank Height (ft)Annual Soil Erosion (ft^3)NBS BEHI Erosion (ft/year)Length (ft)Bank Height (ft)Annual Soil Erosion (ft^3) 0.3 43.23280283 3 38.90952255 1.579080717 MODERATE MODERATE 0.07537.71111855 3 8.485001673 0.344350217 0.075 96.62426153 3 21.74045884 0.882301737 LOW LOW 0.00559.78000856 3 0.896700128 0.03639114 0.075 40.78632283 3 9.176922638 0.372430722 LOW LOW 0.00566.02949292 3 0.990442394 0.04019552 0.005 124.4042706 3 1.866064059 0.075731224 MODERATE MODERATE 0.07526.65319935 3 5.996969853 0.243377426 9 14.26467283 3 385.1461664 15.63054093 MODERATE MODERATE 0.07516.96055295 3 3.816124413 0.154871303 9 10.4422373 3 281.9404071 11.44210032 LOW LOW 0.00523.96318999 3 0.35944785 0.014587616 0.005 67.20720547 3 1.008108082 0.040912454 LOW LOW 0.005119.9182197 3 1.798773296 0.073000336 0.005 6.729104517 3 0.100936568 0.004096349 LOW LOW 0.00510.70640985 3 0.160596148 0.006517538 0.3 76.43146639 3 68.78831975 2.791663896 MODERATE MODERATE 0.07533.4010381 3 7.515233572 0.30499373 9 45.23781516 3 1221.421009 49.56941739 HIGH HIGH 0.338.56855901 3 34.71170311 1.408718932 9 12.44590468 3 336.0394264 13.63762246 MODERATE MODERATE 0.07551.77210026 3 11.64872256 0.472744767 0.075 39.83809604 3 8.96357161 0.363772212 MODERATE MODERATE 0.07527.57430468 3 6.204218553 0.251788283 HIGH HIGH 0.333.06452449 3 29.75807205 1.207683741 LOW LOW 0.00540.40813301 3 0.606121995 0.024598491 TOTAL Annual Soil Erosion (Tons/Year): Erosion (Tons/Year)Erosion (Tons/Year) APPENDIX C Photo Page 1 Site 19 Typical Section – looking downstream Site 19 Cross Section 2 – looking at eroded left bank (failed rock vane) Title Existing Conditions Photo Pages Prepared For Project R2248D Stream Restoration Mecklenburg County, North Carolina Prepared By Date KHA Project Number 11/6/14 011700078