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Home My WebLink About20090356 Ver 1_More Info Received_20090504Wt TMNSITE CONSULTING ENGINEERS, INCORPORATED ENGINEERS • PLANNERS • CEI May 4, 2009 Ms. Cyndi Karoly, Supervisor 401 Oversight/Express Review Permitting Unit 2321 Crabtree Boulevard Raleigh, NC 27604 Attn.: Ms. Lauren Witherspoon Re: DWQ Project # 2009-0356 The Lynden Centre at Crabtree, Raleigh, NC UT to Crabtree Creek [030402, 27-33{10), C, NSW] Dear Ladies, o? ?4 dry Per your REQUEST FOR MORE INFORMATION letter dated April 13, 2009, TranSite Consulting Engineers, Inc. (TCE, Inc.) is pleased to submit the following responses: Additional Information Requested.- Buffer Mitigation Buffer mitigation will be required as a condition if you choose to proceed with the bTnor Variance. If you choose to pay into a mitigation bank for the required mitigation, please provide and acceptance letter from the mitigation bank demonstrating they have the available mitigation credits. We have included, herewith, an acceptance letter from the Ecosystem Enhancement Program for impacts associated with the referenced project. 2. Diffitse Flow Per the requirements of the Neuse Riparian Buffer Rule, you must show that this site meets diffuse flow requirements. See Chapter 8 of the Best Management Practices (BMP) Manual for acceptable die flow devices. Two Preformed Scour Holes (PSH) have been placed on site at the outlets of the drainage pipes to diffuse flow within the restored buffer. A detail for the PSH has been placed on Sheet C 4.3 and velocity computations pertaining to the PSH's have also been provided. We trust that you will find this information sufficient for you to proceed with the review and approval of our variance request. Should you have any questions or need any additional information please do not hesitate to contact us at your convenience. Sincerely, TranSite Consulting Engineers, Inc. --Z? //1- J Douglas B. Saunders, PE Principal 3516 Bush Street, Suite 101, Raleigh, NC 27609 • Phone (919)873-2401 • Fax (919)873-2404 Page 1 of 1 Trailwood Building, LLC PO Box 10961 Raleigh NC 27605 Project: Lynden Center W4 ?000 , rR fie, Expiration of Acceptance: January 29, 2010 County: Wake The purpose of this letter is to notify you that the North Carolina Ecosystem Enhancement Program (NCEEP) is willing to accept payment for impacts associated with the above referenced project. Please note that this decision does not assure that the payment will be approved by the permit issuing agencies as mitigation for project impacts. It is the responsibility of the applicant to contact these agencies to determine if payment to the NCEEP will be approved. You must also comply with all other state, federal or local government hermits, regulations or authorizations associated with the proposed activity including SL 2008-152• An Act to Promote CoM2ensatory Mitigation by Private Mitigation Banks This acceptance is valid for nine months from the date of this letter and is not transferable. If we have not received a copy of the issued 404 Permit/401 Certification/CAMA permit within this time frame, this acceptance will expire. It is the applicant's responsibility to send copies of the permits to NCEEP. Once NCEEP receives a copy of the permit(s) an invoice will be issued based on the required mitigation in that permit and payment must be made prior to conducting the authorized work. The amount of the In Lieu Fee to be paid to NCEEP by an applicant is calculated based upon the Fee Schedule and policies listed at www,nceep.net. Based on the information supplied by you the impacts that may require compensatory mitigation are summarized in the following table. River Basin CU Location Stream (feet) Wetlands (acres) Buffer I (Sq. Ft.) Buffer 11 (Sq. Ft.) Cold Cool Warm Riparian Non-Riparian Coastal Marsh Impact Neuse 03020201 0 0 0 0 0 0 1,216 1,106 Credits Neuse 03020201 0 0 0 0 0 0 3,648 1,659 Upon receipt of payment, EEP will take responsibility for providing the compensatory mitigation. If the regulatory agencies require mitigation credits greater than indicated above, and the applicant wants NCEEP to be responsible for the additional mitigation, the applicant will need to submit a mitigation request to NCEEP for approval prior to permit issuance. The mitigation will be performed in accordance with the Memorandum of Understanding between the N.C. Department of Environment and Natural Resources and the U.S. Army Corps of Engineers dated November 4, 1998. If you have any questions or need additional information, please contact Valerie Mitchener at (919) 715-1973 or Kelly Williams at (919) 716-1921. Sincerely, William D. Gilmore, PE Director cc: Cyndi Karoly, NCDWQ Wetlands/401 Unit Amy Chapman, NCDWQ- Wetlands/401 Unit Doug Saunders, agent File kfftDYG4l?5... 'EKkA"... Prot" Oar State, ern NCDENR North Carolina Ecosystem Enhancement Program, 1652 Mail Service Center, Raleigh, NC 27699-1652 / 919-715-0476 / www.nceep.net Job Desc. /E IN1.?G,Q?/sL?>r- Sheet No. of TRANJITE CONSULTING Subject ENGINEERS, INCORPORATED ENGINEERS PLANNERS CEI Designedby Date TCE Job No. Checked by Date_ FOB' -rl-A6 6VC#?F4,0:,) Cai?i?? ??o??-f ?,?? C?sr?2?a5 - ;5F- -/?/?QP_>JSE?GOuI , <?1/TGY G__', AJ I FICA 17v us 14RO010F , %hf- 5CC%V/Z;_ a(C) (TWA)AA6s s 7fq 010 (n2AW&-e 4' S?rn) = l CF5 u. _ ?• 98 Ftl?5 ffE ato AN.p V!o FofZ (#E _ ale- V/o = tj .fJ F FHWA Urban Drainage Design Program, HY-22 HYDRAULIC PARAMETERS OF OPEN CHANNELS Trapezoidal, Rectangular, or Triangular X-Section Date: 04/30/2009 Project No. . Project Name.:The Lynden Centre Computed by :TCE Project Description North PSH Q10 Outlet Velocity from Drainage System INPUT PARAMETERS 1. Channel Slope (ft/ft) 0.0385 2. Channel Bottom Width (ft) 8.00 3. Left Side Slope (Horizontal to 1) 0.01 4. Right Side Slope (Horizontal to 1) 0.57 5. Manning's Coefficient 0.000 6. Discharge (cfs) 0.00 7. Depth of Flow (ft) 0.00 OUTPUT RESULTS Cross Section Area (Sgft) 0.17 Average Velocity (ft/sec) 3.27 Top Width (ft) 0.67 Hydraulic Radius. (ft) 0.17 Froude Number .25E+155 FHWA Urban Drainage Design Program, HY-22 HYDRAULIC PARAMETERS OF OPEN CHANNELS Trapezoidal, Rectangular, or Triangular X-Section Date: 04/30/2009 Project No. . Project Name.:The Lynden Centre Computed by :TCE Project Description North PSH Q10 Outlet Velocity from Cistern Overflow INPUT PARAMETERS 1. Channel Slope (ft/ft) 0.0100 2. Channel Bottom Width (ft) 8.00 3. Left Side Slope (Horizontal to 1) 0.01 4. Right Side Slope (Horizontal to 1) 1.99 5. Manning's Coefficient 0.000 6. Discharge (cfs) 0.00 7. Depth of Flow (ft) 0.00 OUTPUT RESULTS Cross Section Area (Sgft) 0.35 Average Velocity (ft/sec) 5.70 Top Width (ft) 0.67 Hydraulic Radius (ft) 0.17 Froude Number 0.00 FHWA Urban Drainage Design Program, HY-22 HYDRAULIC PARAMETERS OF OPEN CHANNELS Trapezoidal, Rectangular, or Triangular X-Section Date: 04/30/2009 Project No. . Project Name.:The Lynden Centre Computed by :TCE Project Description South PSH Q10 Outlet Velocity from Drainage System INPUT PARAMETERS 1. Channel Slope (ft/ft) 0.0167 2. Channel Bottom Width (ft) 8.00 3. Left Side Slope (Horizontal to 1) 0.01 4. Right Side Slope (Horizontal to 1) 1.74 5. Manning's Coefficient 0.000 6. Discharge (cfs) 0.00 7. Depth of Flow (ft) 0.00 OUTPUT RESULTS Cross Section Area (Sgft) 0.35 Average Velocity (ft/sec) 4.98 Top Width (ft) 0.67 Hydraulic Radius (ft) 0.17 Froude Number 0.00 FHWA Urban Drainage Design Program, HY-22 HYDRAULIC PARAMETERS OF OPEN CHANNELS Trapezoidal, Rectangular, or Triangular X-Section Date: 04/30/2009 Project No. . Project Name.:The Lynden Centre Computed by :TCE Project Description South PSH Q10 Outlet Velocity from Cistern Overflow INPUT PARAMETERS 1. Channel Slope (ft/ft) 0.0100 2. Channel Bottom Width (ft) 8.00 3. Left Side Slope (Horizontal to 1) 0.01 4. Right Side Slope (Horizontal to 1) 1.99 5. Manning's Coefficient 0.000 6. Discharge (cfs) 0.00 7. Depth of Flow (ft) 0.00 OUTPUT RESULTS Cross Section Area (Sgft) 0.35 Average Velocity (ft/sec) 5.70 Top Width (ft) 0.67 Hydraulic Radius (ft) 0.17 Froude Number 0.00 North American Green 14649 Highway 41 North Material and Performance Specification Sheet Evansville, IN 47725 NORTH 800-772-2040 AGERC FAX: 812-867-0247 ER www.nagreen.com A ter, Company C350 Turf Reinforcement Mat The composite turf reinforcement mat (C-TRM) shall be a machine-produced mat of 100% coconut fiber matrix incorporated into a permanent three- dimensional turf reinforcement matting. The matrix shall be evenly distributed across the entire width of the matting and stitch bonded between a super heavy duty UV stabilized nettings with 0.50 x 0.50 inch (1.27 x 1.27 cm) openings, an ultra heavy UV stabilized, dramatically corrugated (crimped) intermediate netting with 0.5 x 0.5 inch (1.27 x 1.27 cm) openings, and covered by an super heavy duty UV stabilized nettings with 0.50 x 0.50 inch (1.27 x 1.27 cm) openings. The middle corrugated netting shall form prominent closely spaced ridges across the entire width of the mat. The three nettings shall be stitched together on 1.50 inch (3.81cm) centers with UV stabilized polypropylene thread to form a permanent three- dimensional turf reinforcement matting. The C350 shall meet requirements established by the Erosion Control Technology Council (ECTC) Specification and the US Department of Transportation, Federal Highway Administration's (FHWA) Standard Specifications for Construction of Roads and Bridges on Federal Highway Projects, FP-03 Section 713.18 as a Type 5A, B, and C Permanent Turf Reinforcement Mat. Installation staple patterns shall be clearly marked on the turf reinforcement matting with environmentally safe paint. All mats shall be manufactured with a colored thread stitched along both outer edges (approximately 2-5 inches [5-12.5 cm] from the edge) as an overlap guide for adjacent mats. Material Content Matrix 100% Coconut fibers 0.50 Ibs/ d2 0.27 kg/M2) Nettings To and Bottom, UV stabilized Polypropylene 8 Ib/1000 ft2 3.91 kg/1 00 m2 Middle, corrugated UV stabilized Polypropylene 24 Ib/1000 ft2 11.7 kg/1 OOm2 Thread Pol ro lene, UV stabilized C350 is available in the following roll sizes: Width 6.5 ft (2.0 m) Length 55.5 ft (16.9 m) Weight ± 10% 37 Ibs (16.8 kg) Area 40.0 yd2 (33.4 m2) Index Value Properties: Property Test Method Typical Net Only Thickness ASTM D6525 0.67 in 17.0 mm 0.51 in Resiliency ASTM 6524 90% --- Density ASTM D792 0.53 oz/in3 --- Mass/Unit Area ASTM 6566 12.57 oz/ d2 426 /m2 --- Porosity ECTC Guidelines 99% -- Stiffness ASTM D1388 3.83 oz-in Light Penetration ECTC Guidelines 9.0% --- UV Stability ASTM D4355/ 1000 hr ' 86% 86% Tensile Strength MD ASTM D6818 625 Ibs/ft 9.12 kN/m 698 Ibs/ft Elongation MD ASTM D6818 22% 30% Tensile Strength TD ASTM D6818 768 Ibs/ft 11.21 kN/m 710 Ibs/ft Elongation TD ASTM D6818 15% 20% Bench Scale Testin NTPEP : Test Method Parameters Results ECTC Method 2 50 mm 2 in /hr for 30 min SLR** =18.32 Rainfall 100mm 4 in /hr for 30 min SLR** =19.65 150 mm 6 in /hr for 30 min SLR** = 20.48 ECTC Method 3 Shear Resistance Shear at 0.50 inch soil loss 7.5 Ibslft2 ECTC Method 4 Germination Top Soil, Fescue, 21 day incubation 243% improvement of biomass * Bench Scale tests should not be used for design purposes ** Soil Loss Ratio = Soil loss with Bare Soil/Soil Loss with RECP soil loss is based on re ression analysis) Updated 3/09 Performance Design Values: Rou hness Coefficients- Unve . Flow Depth Mannin 's n 50.50ft 0.15m 0.041 0.50-2.0 ft 0.040-0.013 2t 2.0 ft 0.60m 0.012 Product Participant of: DOR" p a~ ~ J W J ~ I f~qY 0 4 BUFFER IMPACTS SUMMARY (SF) z ~ o 2009 DEPdR- WA7Eft l7U~U WETIANDSAND S10RMWAIER B O ~ ~ J N RANC6d TOTAL IMPACTS ~ ~ U ZONE 1 IMPACTS ZONE 2 IMPACTS (ZONES 1 & 2) ® m X = z 2 _ ne._ 0 = t : ~ ~ ~ _ _ ....~~w.. _._.w„._~ ~ , ~ ~ ~ . ~ f3 N10~!OL~TNiC ~ Om~Q _ _ t w ~ ~ t 1SL,~NC~ tT EXISTING 4564 4026 8590 ~ 0 ~ O W t ~ ~ IN 15L~+"(r~ ~~.ZQ PROP. 2'-6" CU~dC & PRC~. a" CitRB GUTTER t GC7TT~ e ~ ~ ~ ADDITIONAL PROPOSED 1216 1106 2322 ~ N ~r m_.. _ .m - ~...w -m.. _ _ ~ a_u~- ~~._.a_ ~ ~ N n _..~_~~e_.. ~ _ _ - G. ~ ~ TOTAL PROPOSED & 5780 5132 10912 . M_ _ _ GONG 5l4 EXISTING i ~ GOPI(;. STE4'S a7 vviUt x ~ , ~~~w,,,, . ~ wt 11" TREAD 7" E,lSE ' . . , PROPOSED REMOVE 1991 343 2334 xx / x I G Y ~ { i , / ' f EXISTING IMPERVIOUS ~ o W Z x x ~ / c I , F-Q_w + - ~ ~ 1 ~ ~ 'i~~ °;p, , i ~ B FINAL TOTAL IMPACTS 3789 4789 8578 0 ~ ~ P / ' t ~o- j x I~ W ~ o x i ~ ~ co~c N~~ Q Z~~" u ~ ~ - ~ r: } r , ~ ~ x ~ F ' DELTA FINAL TO EXISTING 775) 763) (-12) ~ Q o Q ~ _ a p 00 x x x x ' a~ ~ ~ ~ ~ u ~ ~ ~ 7 ,fix TOTALAREA OF ZONE 1 BUFFER WITHIN PROPERTY BOUNDARY = 8218 SF (0.19AC) c ~ ~ W / - W u TOTALAREA OF ZONE 2 BUFFER WITHIN PROPERTY BOUNDARY = 5366 SF (0.12 AC) w Z x ~ ( } ~ i rl W A Z ~ ~ ~ ~ EXISTING: TOP OF BANK E ISTINC~~ TOP OF BANK ~ se of BANK TOTAL =13584 SF (0.31 AC) ~ Z ~ w ~j • ~ u' ~ ~ x Q U v~ 1~~ Z _ ~ ~ r~~, ~ ~ ~ , i t ~ ~ , i- w 0 ~ ~ ~ ~ ~ ~ ~a MITIGATION ~ r ~ ~ ~ ~ ~ ' PREFORMED:S000R ~ x SCOUR ZONE 1 =1,216 sf x 3 = 3,648 sf; 3,648 sf x $0.961sf = $3,502.08 s ~ x , E ~ HALE (PSH) / ~x ~ ~ SEE DETAIL ZONE 2 ZONE 2 1 ~ xx ~ ZONE 2 =1,106 sf x 1.5 =1,659 sf;1,659 sf x $0.96Isf = $1,592.64 ~ ~ G t ~ ! ( / ,x \ ~ ( i ~ x / . ~ ~ ~ r , ~ i 1 u ~ ~ , ~ x, i x `x 3 / x _ ~ a, ~ ~ ,f ~ u~ . x~x~ PREFORMED SCOUR HOLE o,m, ~~~na . ~~,~~z.~~ h~ _ C~ ' ~C PLAN VIEW x 1 k x ~ .x . , Pipe Outle - . x- A A xx . - - ~ . , ~ i ~ ZONE 1 d.l.l ZONf:I ~ ~ x ~ ~ ~ ~ i ~x Square Preformed with Natural Grounidsh z x ~x x~ Scour Hole (PSH) W W x x x xx x U ~ x~ X Z ~ O , ~ ~ ~ ix x ~ / ~ x~, / I SECTION A-A O ~ ~ -N e r; ~.x x I ~ ~ ~ x~ i Pipe Outle Turf Reinforcement Matting z = U i 'x North American Green C350 ~ z Or Approved Equal F- ~ x ~ x / ~ ~ 1 / j `fix 1' Natural Ground J 0 X / ~ ~ ~ ~ W z ?~r 21 W ' V V ~ ~ ~ 1'Tuck 1'Tuck L= ~ J x ~ / \ r x t ~4-' I~ N ~ x x x X ~ } m x y / x ~ ~ ~'~Y / ~ ~r xx ~ i ~ i ~ ~ ~ _ six x i~ -i x~h X ~ ~ ~ ~ ~i ~ ~ F x , , PREFORMED SCOU x NOLE PSH ORMED SCOUR )ETAIL NOTE: EXISTING RIP RAP LOCATED WITHIN ZONE 1 BUFFER, AND OUTSIDE OF TOP x ~ ~ ` SEE DETAI d.~rw~m _ m y~ ~ ~ ~ OF BANK, IS TO BE REMOVED DURING CONSTRUCTION, SEE STORMWATER ~ x ~ PLAN C 4.2. ENTIRE ZONE 1 BUFFER AREA IS TO BE REESTABLISHED WITH p ® ii x ~ HIGH QUALITY PLANTINGS, SEE LANDSCAPING PLAN C 6.1. ~ X~ t ~ ~ A ~ Z 0 Y. °~q O U t 1 k?r'..'k - _ W _ m~ ~ ~ 1 v~'+wmvwnt aW"m.. m ^w- t j 3` W t t z 'rte. ~ ~ m, , , f ~ ~ a r i r f °w,,, . { ~ , ti.~ ~Gr r M 4. ~ p ~w ~ r i • ~ w ' PROP. 2'-6 CURD&--°` . -LEGEND - ~b~ GUTTER M~ F 3 0 Z t aaTE: 03-23-09 i s w, ' ~ ~ ~ p - ~ _ ~'~f / I ZONEIBUFFER PREL~M~NARY PLANS oRawwpR; cHECpgSav: _ FILE NAME: ~ PROP. C URN & NOT fOR CONSTRUCTION doa ~NUMeER: Psh_Buffer -~~TTEft ~ j ZONE 2 BUFFER 107.049.001 a.. .M ~i ~ DATE PRINTED 04-30-09 ~ _ BUFFER TRANSMITTED gY TranSite Consult. Engrs. IMPACTS ZONE16UFFERIMPACTS PLAN \ u u u\ u\ v\ u ~ ZONE 2 BUFFER IMPACTS SCALE SNEET ~IOo . ~ w ® ® ® a GYICTIAIG RI IFFFR IAAPACTR TO BE REMOVED 20 0 10 20 UFFER IMPACTS LAN C 4.3 ( IN FEET ) PLOT DATE. 04-30-09 THIS DRAWING IS A COPYRIGHT OF TRANSITE CONSULTING ENGINEERS, INC., NC, 2006.