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Home My WebLink About20071212 Ver 1_Mitigation Reports_20070808~atunil Rr~~nut•~ 12~ ~k nati~m ~l ('~ ~mrt~ ;Uiun August 8, 2007 North Carolina Department of Environment And Natural Resources Division of Water Quality 401 Oversight and Express Review Program 1650 Mail Service Center Raleigh, NC 27699-1650 ATTENTION: Eric Kulz, Stream Mitigation Specialist RE: Brown Marsh Swamp Stream and Wetland Mitigation Site -Full Delivery Project; 2nd Response to DWQ Letter dated July 27, 2007; DWQ #07-1212 We regret that we misunderstood specifics of your concern as expressed in your July 27 letter and your August 6 e-mail. Yesterday's meeting between you and our designer, Ryan Smith (Ko & Associates) enlightened us and provided you with a better picture of the unique aspects of the project. We have revised the morphological tables for both tributaries to address your concerns about how we calculated valley slope. We are confident that this information will bring resolution to the single outstanding issue. Please review this material when you return to the office. An acknowledgement of your concurrence with this new information will be appreciated. Again, we appreciate the constructive technical input you are providing on our projects. We are only interested in building restoration projects that will function as intended. Your further cooperation in advancing the issuance of the 401 approval will be appreciated. We are interested in scheduling mobilization of the contractor ASAP. If you have any questions or need additional information, please do not hesitate to contact us at Restoration Systems at 919.755.9490 (random(c~,restorationsystems.com) or Ko & Associates at 9 t 9.851.6066 (rsmith _,koassociates.com). Thanks for your time. Sincerely, _~ ~~~~c~ ~~~y~r~ M. Randal Turner Enclosures cc: Cyndi Karoly, NCDWQ Ryan Smith/Kevin Williams, Ko & Associates, P.C. Worth Creech, RS Kim Garvey, USACE Pilot Mill • 1101 Haynes St.. Suite 107 • Raleigh. NC 27604 • ww~w.restorationsystems.com • Phone 919.755.9490 • Fax 919.755.9492 Morphological Characteristics: Northern UT Restoration Plan: Brown Marsh Swamp Stream and Wetland Restoraiton Site County: Robeson County, NC Design by. RVS Checked by RKW ITEM Existin Conditions Pro oser,' Conditions Reference Reach Reference Reach ReferBnce Reach LOCATION Existin Northern UT Northern UT UT to Ironhill Branch Mill Creek UT to Wildcat Branch STREAM TYPE G5 E5 E5 E5 E5 DRAINAGE AREA, Ac - Sq Mi 723.20 Ac - 1.13 S Mi 723.20 Ac - 1.13 S Mi 1030.40 Ac - 1.6i S MI 1228.80 Ac - 1.92 S Mi 2$1.60 Ac - 0.44 S Mi BANKFULL WIDTH (W~,~), ft 10.7 ft 11.5 ft 10.3 ft 11.3 ft 8.2 fl BANKFULL MEAN DEPTH (doa), ft 1.85 ft 1.53 ft 0.95 ft 1.85 ft 1.03 fl IDTH/DEPTH RATIO (W„~Id~) 5.8 7.5 10.8 6.1 8.0 BANKFULL X-SECTION AREA (Aykr), ftZ 19.7 ft2 17.8 ft2 9.8 ft' 21.0 ft2 8.5 ft2 BANKFULL MEAN VELOCITY, fps 0.9 f s 1.1 f s 1.1 s 1.6 f s 1.0 i s BANKFULL DISCHARGE, cfs 18.1 cfs 18.1 cis 10.3 cfs 30.6 cis 8.5 cfs BANKFULL MAX DEPTH (dm,,,), ft 2.86 ft 1.52 ft 1.58 ft 2.58 ft 1.57 ft WIDTH Flood-Prone Area (W~„), ft 21.7 ft 35.00 ft 290.0 ft 300.0 ft 130.0 fl ENTRENCHMENT RATIO (ER) 2.0 3.0 28.2 26.5 15.9 MEANDER LENGTH (Lm), ft 1500 - 1500 ft 34.5 - i 15.0 ft 42.0 - 72.0 ft 37.7 - 72.6 ft 22.5 - 29.0 ft RATIO OF Lm TOWS 140.7-140.7 3.0-10.0 4.1-7.0 3.3-6.4 2.7-3.5 RADIUS OF CURVATURE, ft 150 - 400 ft 23.0 - 34.5 ft 13.7 - 20:8 ft 9,7 - 29.8 ft 10.9 - 15.3 ft RATIO OFRcTOWod 14.1-37.5 2.0-3.0 1.3-2.0 0.9-2.6 1.3-1.9 BELT WIDTH, ft 600.00 - 600.00 ft 23.0 - 69.0 ft 30.0 - 59.0 ft 15.1 - 27.0 ft 13:8 - 19.4 ft MEANDER WIDTH RATIO 58.29 -56.29 ft 2.0 - 6.0 2.9 - 5.7 1.3 - 2.a 1.7 - 2.a SINUOSITY (K) 1.00 1.39 1.33 1.18 1.15 VALLEY SLOPE, fUft 0.0016 fUft 0.0013 ft/ft 0.0017 fUft 0.0031 ft/ft 0.0027 ft/ft AVERAGE SLOPE (S), fUft 0.0010 ft/ft 0.0010 fUft 0.0013 fUft 0.0026 ft/ft O.D024 ftrft POOL SLOPE, fUft 0.0000 fUft 0.0004 ft/ft 0.0015 - 0.0065 fUft 0.0000 - 0.0080 fUft 0.0000 - O.000D ft/ft RATIO OF POOL SLOPE TO AVERAGE SLOPE 0.0 0.4 1.2-5,0 O.D-3.0 0.0-0.0 MAX POOL DEPTH, ft 2.61 ft 3.07 ft 1.50 ft 3112 ft 1,75 ft RATIO OF POOL DEPTH TO AVERAGE BANKFULL DEPTH 1.4 2.0 1.6 1.7 1,7 POOL WIDTH, ft 10.7 ft 12.65 ft 16.10 ft 11.85 ft 8.$3 fit RATIO OF POOL WIDTH TO BANKFULL WIDTH 1.0 1.10 1.67 1.05 1.08.. POOL TO POOL SPACING, ft 60.00 - 140.00 ft 27.6 - 70.3 ft 40.0 - 65.0 ft 11.4 - 61.0 ft 14.0 - 16.6 ft RATIO OF POOL TO POOL SPACING TO ANKFU L WIDTH 5.83 - 13.13 ft 2.4 - 6.1 3.9 - 6.3 1.0 - 5.4 1.7 - 2.0 Note: valley slope was derived by using elevations at existing ground at the beginning (upstream) and ending (downstream) project limits. The proposed alignment has been relocated to its historic valley. The historic valley is east of the existing valley and has a longer valley distance, which constitutes the difference between existing and proposed valley slopes for the Northern UT. Morphological Characteristics: Southern UT Restoration Plan: Brown Marsh Swamp Stream and Wetland Restoraiton Site County: Robeson County, NC Design by: RVS Checked by: RKW ITEM Existin Conditions Pro osed Conditions Reference Reach Reference Reach LOCATION Southern UT Southern UT UT to Wildcat Branch U7 4p Swam STREAM TYPE E5 E5 E5 ES DRAINAGE AREA, Ac - Sq Mi .115.20 Ac - 0.18 S Mi 115.20 Ac - 0.1$ S Mi 281.60 Ac - D.44 S Mi 48:00 Ac - 0.085 Mi BANKFULL WIDTH (W~), ft 5.6 ft Z5 ft $.2 ft 3.$ ft BANKFULL MEAN DEPTH (dam), ft O,g1 ft 0.79 ft Y,03 ft 0,48 ft WIDTH/DEPTH RATIO (W y,Q/dyy) 6.1 9.5 $.0 7.9 BANKFULL X-SECTION AREA (A~), ftZ 3.0 ft2 5.9 ft2 $.S ft? 1.8 ft3 BANKFULL MEAN VELOCITY, tps 1.6 f s 0.8 fps 1.Okps 1,3 t 5 BANKFULL DISCHARGE, ds 4.9 cfs 4.9 cfs 8.5 cfs 2:3 Cfs BANKFULL MAX DEPTH (dma„), ft 1.24 ft ___ 1.60 ft 1,52 fi 0:72 ft WIDTH Flood-Prone Area (W~,), ft 7,21 ft iS.OD ft 13D 0 ft 100.0 ft ENTRENCHMENT RATIO (ER) 1 3 2 0 15 9 26.fi MEANDER LENGTH (Lm), ft 800.0 22.5 - 75.0 ft 22:5 - 28:0 ft 12.U - 70.0 ft RATIO OF Lm TOWS, 143.9 3.0-10A 2.7-35 . 3.2-18.8 RADIUS OF CURVATURE, ft 65.0 15.0 - 22.5 fl 10.9 - 15.3 fi 4 4 - 45.6 ft RATIO OF Rc TO W ~, 11.7 2.0 - 3.0 9.3 - 1.9 1:2 - 12.i BELT WIDTH, ft 100.D 15.0 - 45.0 ft 13.8 - 19,4 ft" 5,7 - 16.D ft MEANDER WIDTH RATIO 18.0 _ 2.0 - 6.0 1.7 - 2.4 LS - 42 SINUOSITY (K) 1.00 1.21 1.15 1 24 VALLEY SLOPE, fUft 0.0022 ft/ft 0.0022 fUft 0.0027 filft tD.00$4 ft/ft VERAGE SLOPE (S), ft/ft 0.0003 ft/ft _ D.0029 fttft OA024 fVtt 0.006(3"ft/ft POOL SLOPE, fUft RATIO OF POOL SLOPE TO AVERAGE SLOPE 0.0000 ft/ft 0.0 0.0011 Rift - 0.4 _ O;D000 - O.U000 ftlft 0.0 - D D 0.0060 - 0.0066 , ,, D 0 • 0.9_ MAX POOL DEPTH, ft 0.94 ft 1.9T ft 1.75 ft 1.10 $ , RATIO OF POOL DEPTH TO AVERAGE BANKFULL DEPTH 1.0 2.5 1.7 2.3 POOL WIDTH, ft 4.96 ft 7.50 ft $:83 ft 3.80 H RATIO OF POOL WIDTH TO BANKFULL WIDTH 0.89 1.00 1.08 1.01 POOL TO POOL SPACING, ft RATIO OF POOL TO POOL SPACING TO BANKFULL WIDTH 4.7 - 54.1 ft 4.7 - 9.7 18.0 - 45.8 ft 2.4 - 6.1 14:0 - 16.6 ft 1.7 - 2.0 9.0 - 23:0 fk" 2.4 - 6:1 --• •• ~ ~r ~~„,y a,a.=~~~~ ~ o~ ~n~~~~~~y y~ uunu m uie uegmmng tupsUeam) anD enD~ng (Downstream) project limits. The existing and proposed alignments are both boated within the Southern UT's historic valley.