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Home My WebLink About20070930 Ver 1_Stormwater Info_20070525 Stormwater & Level Spreader Calculations Project: Ridge Park Date: 5/25/2007 By: Lewis Hardee John A. Edwards & Co. 333 Wade Avenue Raleigh, NC 27605 (919) 828-4428 DIVISION OF WATER QUALITY • LEVEL SPREADER WORKSHEET (112007) I. PROJECT INFORMATION (please complete the following information): Project Name : Ridge Park - Ralei4h, NC Contact Person: John A. Edwards & Co. -Lewis Hardee Phone Number: (9191828-4428 Level Spreader ID: _ Level Spreader Level Spreader Length 120 ft. (perpendicular to flow) Drainage Area 5.74 ac. (on-site and off-site drainage to the level spreader) Impervious Area 1.93 ac. (on-site and off-site drainage to the level spreader) Forebay Area 336 cu ft. (0.2% of the contributing impervious surface area) Maximum Filter Strip/Buffer Slope 6.0 % (6% for forestedlleaf littler cover, 8% for grasslthick cover) Max. Discharge from 1"/Hr Storm 1.8 cfs Max. Discharge to Level Spreader 1.83 cfs (Discharge rate from extended detention wetland or pond) Filter Stripl Zone 1 Buffer Vegetation Forested (GrasslThick ground cover or Forested) Filter Strip/ Zone 1 Buffer Width 90 ft. Filter Stripl Zone 2 Buffer Vegetation Forested Filter Stripl Zone 2 Buffer Width 111 ft. Bypass Method Used Flow Splitter Box to Reinforced Grass Swale Please include a worksheet for this. II. REQUIRED ITEMS CHECKLIST Initial in the space provided to indicate the following design requirements have been met and supporting documentation is attached. If a requirement has not been met, please explain why. At a minimum, a complete stormwater management plan submittal includes a worksheet for each BMP, design calculations, plans and specifications showing all BMPs and outlet structure details, a detailed drainage plan and a fully executed operation and maintenance agreement. An incomplete submittal package will result in a request for additional information and will substantially delay final review and approval of the project. Applicants Initials LEH Project Site was visited prior to designing level spreader system. LEH Date of the Site visit. Please attach time-dated digital photos of existing buffer conditions. LEH Level spreader length is at least: l3 ft. per cfs for thick ground cover /grass; OR 65 ft per cfs for 50- footcanopied forest with leaf litter; 50 ft per cfs for 100-foot forested buffer; 40 ft. per cfs for 150-foot forested buffer; OR a weighted average of the two vegetation types within the bufferlfilter strip). LEH All ground cover types and their widths have been labeled on the construction plans. LEH All contours have been depicted on the construction plans. LEH No structures are located in protected buffers (must meet no practical altematives criteria). LEH No draws are located in the buffer or filter strip in the vicinity of the proposed level spreader. LEH Construction details for the level spreader have been provided. LEH The operation and maintenance agreement signed and notarized by the responsible party is provided. LEH No practical altematives explanation + Variance request. (Level Spreaders in Series only). Bypass method used: LEH Bypass conveyance method is specified and construction details and calculations are provided. LEH Alternative design option is specified and plan details and calculations are provided. LEH Discharge to level spreader and subsequent filter strip is hydraulically and spatially separate from the bypass discharge. LEH Construction details for the bypass and outlets are provided. & BYPASS CHANNEL AREA PHOTOGRAPHS FROM THE PROPOSED LEVEL SPREADER LEVEL SPREADER SYSTEM OPERATION AND MAINTENANCE AGREEMENT (1/2007) A level spreader system includes: a forebay, diverter box, level spreader, riparian buffer/vegetated filter strip, and flow bypass channel. Name of Project: Ridge Park Address: 3531 Horton St. -Raleigh. NC Maintenance activities shall be performed as follows: MAINTENANCE ACTIVITY FREQUENCY Post-construction monitoring-inspect for vegetation, Check after every heavy rainfall for first 6 months settlin ,erosion, or concentrated flow. followin construction. Inspect Diverter Box and clean and/or make repairs. Once a month and after heavy rainfalls/storms. Look for: • Clogged inlet or outlet pipes. • Trash/debris in the box. Inspect Forebay + Level Spreader. Clean and/or Once a month and after heavy rainfalls/storms. make repairs. Look for: • Sediment in forebay and along level spreader lip; • Trash and/or leaf buildup. • Scour, undercutting of level spreader. • Settlement of level spreader structure (no longer level; you see silt downhill below level spreader). • Fallen trees on level spreader. • #57 stone washin downhill. Inspect the Riparian Buffer and the Bypass Swale Once a month and after heavy rainfalls/storms. and make repairs as needed'. Look for: • Damaged turf reinforcement or riprap rolling downhill. • Erosion within the buffer or swale. • Concentrated flows downhill of level s reader-look for ullies or sediment flows. Mow grass to a 6" height. As needed during growing season. Remove any weeds/shrubs growing on level spreader Once a year. or in swale. ~ NOTE: Contact NC Division of Water Quality, 401/Wetlands Unit at 919-733-1786 BEFORE any work in Protected Riparian Buffers. Page 1 of 2 LEVEL LOCATION ON SITE (DESCRIBE) HOW WILL IT BE ACCESSED? SPREADER NO. 1 Below wall and down slope from the North By public street and then by foot Level S reader side of the ublic cul-de-sac I acknowledge and agree by my signature below that I am responsible for the performance of the maintenance procedures listed above. I agree to notify DWQ of any problems with the system or prior to any changes to the system or responsible party. Print name: C. Gradv Matthews Title: Principal -Granite /Raleigh, LLC Address: 111 North Bovlan Ave. -Raleigh. NC Phone: (919) 787-6405 Signature: Date: Note: The legally responsible party should not be a homeowners association unless more than 50% of the lots have been sold and a resident of the subdivision has been named the president. I, , a Notary Public for the State of , County of , do hereby certify that personally appeared before me this day of ,and acknowledge the due execution of the forgoing wet [wetland] detention basin maintenance requirements. Witness my hand and official seal, SEAL My commission expires Page 2 of 2 ~zow sn~1T~~~' ,~o~l' G~4u-~/~-~i~ivs ~QU~4ToNS : Gv~~- Q =GwL f/3~ o~iClc~- Q =CD ~1~ OR/PIGS.' Q= Q./ . ' L S Gy =..f9 a = coA~ /B=.Sv(~ z~ h 91 = 3Z Z f~fscc Z fi~° So~/~ ~~ ~~~o ~ET~RM/A/ ~JEI~ Q . GwLN~/z /6.9~ ~3Xs)M~ ~=/os~~ Ov~2~T ~i~~ x,,'3.0 ,y~Ir~r =5~~~ ~ = s~ (,~~IR f ~l~fT -~11-N1 t ORlF1 ~~ ~4D~Us = 2.7 S ~'t. -l3R' ~~SS~pA-i'~ ~ ~5C C'~5S / f~IPP~P -~ ~'~s Q2 ... _......... HYDRAULIC RESULTS Discharge cfs Peak Flow Period hrs Vebcfty (fpsJ Area (sq.ftJ Hydraulic Radius ft Normal De h ft h 3.5 0.1 3.52 3.83 0.54 1.13 LINER RESULTS Not to Scale Reach Material T e Phase Ve . T Sod Type Manning's'n' Permissible Cabulated Safety Remarks Sta a Pattern Class Ve . Densit Shear Stress (psf) Shear Stress (psf) Factor Straght C350 3 0.049 8.00 2.19 3.66 STABLE Staple E Default ~'YP/3S5 G~~N/1/~L •~ ~~/~JiDQC'-~1~ ~1+~'~SS S~~l,~ 3 0 Width 0 00 ft 3 0 ~~I55 C~il/rl/~G .' ,~/~/,~eC~O ~,eAss scJ,~ Ql0 'ROM STATIONlREACH: HYDRAULIC RESULTS _ _ RAINAGE AREA; _ ESIGN FREQUENCY: Discharge cfs Peak Fbw Period hrs Velocity (fps Area (sq.ftJ Hydraulic Radius ft Normal De ft h 6.9 0.1 3.73 4.53 0.58 1.23 LINER RESULTS Not to Scale Reach Material T e Phase Ve . T Soil Type Manning's'n' Permissible Calculated Safety Remarks Sta a Pattern Class Ve . Densit Shear Stress (psfJ Shear Stress (psfJ Factor Straght C350 3 0.049 8.00 2.38 3.36 STABLE Staple E Defauq Bottom 0 Width - 0.00 ft 3. MATERIAL SPECIFICATIONS CATEGORY I C350 The composite turf reinforcement mat (C-T1uVI) shall be a machine produced mat of 100% coconut fiber matrix incorporated into a permanent three dimensional netting structure. The matrix shall be stitch bonded between a heavy duty UV stabilized bottom net with 0.50 x 0.50 inch (1.27 x 1.27 cm) openings, a super heavy duty UV stabilized, dramatically cuspated (crimped) intermediate netting with 0.50 x 0.50 inch, (1.27 x 1.27 cm) openings, over lain with a heavy duty UV stabilized top net with 0.50 x 0.50 inch (1.27 x 1.27 cm) openings. The cuspated 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 (3.81 cm) centers with UV stabilized polypropylene thread to form a permanent three dimensional structure. All mats shall be manufactured with a colored thread stitched along both outer edges (approximately 2 - 5 inches [5-12.7 cm] from the edge) as an overlap guide for adjacent mats. The composite turf reinforcement mat shall be the North American Green C350, or equivalent. The C350 permanent composite turf reinforcement mat shall have the following physical properties: Material Content Matrix 100% Coconut Fiber, (0.50 lb/yd2 [0.27 kg/m2]) Nettings Top -Heavy UV Stabilized Polypropylene 8.50 lbs/1,000 ftz (4.15 kg/100 m2) Mid -Super heavy UV Stabilized Polypropylene 201b/1,000 ftz (10.21 kg/100 m2) Bottom -Heavy UV Stabilized Polypropylene 8.50 lbs/1,000 ftz (4.15 kg/100 m2) Thread UV Stabilized Polypropylene Physical Specifications (per roll) English Width 6.50 ft Length 55.50 ft Weight 37.00 lbs + 10% Area 40.00 yd2 Metric 2.00 m 16.90 m 16.80 kg 33.40 m2 S'~APLE PATTERN "E" 3.75 staples/yd^2 (4.5 staples/m^2) using 6 in (15.2 cm), 11 ga. wire "U" staples. 8 in (20.3 cm) 4 staples and longer may be (1 used for loose soils. 9 ga. staples or heavier may be necessary in hard or rocky soils. Secure blankets to soil by placing a staple/stake through each YELLOW colored dot. NORTH AMERICAN GREEN 6.67ft (2.Om)