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Home My WebLink About20060659 Ver 3_More Info Received_20120330WITHERS i- RAVENEL ENGINEERS I PLANNERS I SURVEYORS 111 MacKenan Drive CARY, NORTH CAROLINA, 27511 (919) 469 3340 FAX (919) 467 6008 TO NCDWQ WE ARE SENDING YOU ❑ Shop Drawings ❑ Copy of Letter ® Attached via ® Prints ❑ Change order LEUM OF 7 ° ° N§MffUAL DATE 03 30 12 IJOBNO 2050018 ATTENTION Lauren Witherspoon / Karen Higgins PHONE # RE The Woods at Umstead ❑ For review and comment b -0 Lo Set 3 the following items ❑ Plans ❑ Samples ❑ Specifications ❑ Diskette ❑ COPIES DATE NO DESCRIPTION 3 ❑ Returned for corrections ❑ For review and comment Bypass Channel Calcs 3 LS VFS 3 O & M Agreement 3 Stormwater Management Details 1 CD THESE ARE TRANSMITTED as checked below ® For approval ❑ Approved as submitted ❑ For your use ❑ Approved as noted ❑ As requested ❑ Returned for corrections ❑ For review and comment ❑ ❑ Resubmit copies for approval ❑ Submit copies for distribution ❑ Return corrected prints ❑ FOR BIDS DUE 20 ❑ PRINTS RETURNED AFTER LOAN TO US Date COPY TO File SIGNED Amy McDonald If enclosures are not as noted kindly notify us at once woods 0 Umstead - Bypass Channel Project Description Friction Method Solve For Input Data Roughness Coefficient Channel Slope Left Side Slope Right Side Slope Discharge Results Normal Depth Flow Area Wetted Perimeter Top Width Critical Depth Critical Slope Velocity Velocity Head Specific Energy Froude Number Flow Type GVF Input Data Downstream Depth Length Number Of Steps GVF Output Data Upstream Depth Profile Description Profile Headloss Downstream Velocity Upstream Velocity Normal Depth Critical Depth Channel Slope Critical Slope Manning Formula Normal Depth Supercritical 0 040 007600 ft/ft 300 Rift (H V) 300 ft/ft (H V) 600 ft' /s 065 It 128 ft' 413 ft 392 ft 076 ft 003458 Wit 469 ft/s 034 ft 099 It 145 000 ft 000 ft 0 000 ft 000 ft Infinity ft/s Infinity fits 065 ft 076 ft 007600 Rift 003458 fttft ,: p.K • �� q,c ao�L V& C- 1 144 1g 0 1rN M7 OWNS r CD Bentley Systems, Inc Haested Methods Solution Center Bentley FlowMaster (08 01 071 00) 1112/2012 11103 50 AM 27 Slemons Company Drive Suite 200 W Watertown CT 06795 USA +1203-755-1666 Page 1 of 1 Appendices Table 8 059 Permissible Unit Shear Stress Td Permissible Shear Stresses Lining Category Lining Type (IbKP) for Riprap and Temporary Liners Temporary Woven Paper Net 015 Jute Net 045 Fiberglass Roving Single 060 Double 085 Straw with Net 145 Curled Wood mat 155 Synthetic Mat 200 d5o Stone Size (inches) Gravel Riprap 1 , 033 2 067 Rock Riprap 6 200 9 30 12 4 00,g-I D 15 500 21 780 24 800 Adapted From FHWA, HEC 15 April 1983 pgs 17 & 37 Design Procedure- The following is a step -by step procedure for designing a temporary liner for Temporary Liners a channel Because temporary liners have a short period of service the design P rY Q may be reduced For liners that are needed for six months or less the 2 year frequency storm is recommended Step 1 Select a liner material suitable for site conditions and application Detemunc roughness coefficient from manufacturer s specifications or Table 8 05e page 8 05 10 Step 2 Calculate the normal flow depth using Manning s equation (Figure 805d) Check to see that depth is consistent with that assumed for selection of Manning s n in Figure 8 05d page 8 05 11 For smaller runoffs Figure 8 05d is not as clearly defined. Recommended solutions can be determined by using the Manning equation Step 3 Calculate shear stress at normal depth Step 4 Compare computed shear stress with the permissible shear stress for the liner Step 5 If computed shear is greater than permissible shear adjust channel dimensions to reduce shear or select a more resistant lining and repeat steps 1 through 4 Design of a channel with temporary lining is illustrated in Sample Problem 8 05b page 8 05 14 Rev 12193 80513 OF �ArFR AMPA W > � P r NCDENR STORMWATER MANAGEMENT PERMIT APPLICATION FORM 401 CERTIFICATION APPLICATION FORM LEVEL SPREADER VEGETATED FILTER STRIP (LS VFS) SUPPLEMENT This form must be completely filled ou4 printed Initialed and submdted 1 PROJECT WORM 00N , �_ ; '' t k � — t 1 , U v Project name The Woods at Umstead Contact name Hunter Freeman Phone number 919- 469.3340 Date January 12 2012 Drainage area number t 11 DESIGN INFORMATION The purpose of the LS VFS Buffer Rule Diffuse Flow Stormwater enters LS VFS from A BMP Type of VFS Engineered filter strip (graded & sodded slope < 8%) Explanation of any Other' responses above B Stormwater Enters the LS-VFS from the Drainage Area Drainage area Impervious surface area Percent impervious Rational C coefficient Peak flow from the 1 in/hr storm Time of concentration Rainfall intensity 10-yr storm Peak flow from the 10•yr stone Design storm Maximum amount of flow directed to the LS VFS Is a flow bypass system going to be used? Explanaton of any Other' responses above If Stormwater Enters the LS -VFS from a BMP Type of BMP Peak discharge from the BMP during the design storm Peak discharge from the BMP during the 10•year storm Maximum capacity of a 100 -foot long LS VFS Peak flow directed to the LS-VFS Is a flow bypass system going to be used9 Explanation of any Other' responses above LS-VFS Design Foeebay surface area Depth of forebay at stormwater entry point Depth of forebay at stormwater exit point Feet of level lip needed per cis Computed minimum length of the level lip needed Length of level lip provided fe fe °6 cis mm In/hr CIS Do not complete this section of the form Do not complete this section of Me form Do not complete this section of the form Do not complete this section of the form Do not complete this section of the form Do not complete this section of the form Do not complete this section of the form Do not complete this section of the form cis Do not complete this section of the form (Y or N) Do not complete this section of the form Other Explained below � O ES dO✓r'y9�i 02W2 b c1NF�+��: Iti1R�\`` 02 cis 02 cis 10 cis 02 cis Y (Y or N) Dry Detention & Splitter Box 0 sq ft No forebay is required. 0 m 0 In Too shallow 10 fVds 2 it Ten feet is the minimum level spreader length 10 it Form SW401 LS VFS 27Ju12011 Rev 9 page 1 of 3 Width of VFS Elevation at downslope base of level Iii Elevaton at the end of the VFS that is farthest from the LS Slope (from level Np to the end of the VFS) Ara any draws present in the VFS? Is there a collector swale at the end of the VFS? Bypass System Design (If applicable) Is a bypass system provided? Is there an engowred flow splitting device? Dimensions of the channel (see diagram below) M IN y (flow depth for 10 -year skimn) heeboard (dumg the 10•year stone) Peak velocity in the channel during the 10•yr storm Channel lining material Does the bypass discharge through a wetland? Does the channel enter the stream at an angle? Explanation of any 'Other' responses above 30 34100 fmsl 34000 fmsl 333 % N (Y or N) N (Y or N) Y (Y or N) Y (Y or N) 300 it 000 it 1200 it 065 it 1.35 it 469 Nsec N (Y or N) Y (Y or N) ll OK Please provide plan details of flow spldter & supporting calcs. B A III REQUIRED ITEMSCHECKLIST� EDIT Please indicate the page or plan sheet numbers where the supporting documentation can be found An incomplete submittal package will result In a request for additional information This will delay final review and approval of the project Irnbaf in the space provided to indicate the following design requirements have been met If the applicant has designated an agent the agent may mused below If a requirement has not been met, attach justification Required Item I Plans (1 50 or iargel of the entire alto showing Design at Ornate twhd -out, Off site drainage (if applicable) Delineated drainage bastite (include Rational C coefficient per basin) Forebay (I applicable) High flow bypass system Maintenance access, Proposed drainage easement and public right of way (ROW) and Boundaries of drainage easement initi Page or plan sheet number and any notes Form SW401 LS VFS 27Ju12011 Rev 9 page 2 of 3 2 Plan details (1 = 30 or larger) for the level spreader showing Forebay (d applicable) High flow bypass system One foot topo lines between the level Up and top of stream bank Proposed drainage easemeK and Deign at ultimate buld -out. 3 Section view of the level spreader (1 - 2V or larger) showing Underdram system (d applicable) Level lip Upstope channel and Downslope filter fabm 4 Plan details of the flow splitting device and supporting calculations (d applicable) 6 A construction sequence that shows how the level spreader will be protected from sediment until the entire dunnage area a stabilized 6 If a non engineered VFS is being used than provide a photograph of the VFS showing that no draws are present. 7 The supporting calculations. 6 A copy of the signed and notarized operation and maintenance (O&M) agreement Form SW401 LS VFS 27Ju12011 Rev 9 page 3 of 3 Permit Number (to be provided by DWQ) Dramage Area Number Filter Strip, Restored Riparian Buffer and Level Spreader Operation and Maintenance Agreement I will keep a maintenance record on this BMW This maintenance record will be kept in a log in a known set location Any deficient BMP elements noted in the inspection will be corrected repaired or replaced immediately These deficiencies can affect the integrity of structures safety of the public and the removal efficiency of the BMP Important maintenance procedures — Immediately after the filter step is established any newly planted vegetation will be watered twice weekly if needed until the plants become established (commonly six weeks) — Once a year the filter strip will be reseeded to maintain a dense growth of vegetation — Stable groundcover will be maintained in the drainage area to reduce the sediment load to the vegetation — Two to three tunes a year grass filter strips will be mowed and the clippings harvested to promote the growth of thick vegetation with optimum pollutant removal efficiency Turf grass should not be cut shorter than 3 to 5 inches and may be allowed to grow as tall as 12 inches depending on aesthetic requirements (NIPC 1993) Forested filter strips do not require this type of maintenance — Once a year the soil will be aerated if necessary — Once a year soil pH will be tested and line will be added if necessary After the filter strip is established it will be inspected quarterly and within 24 hours after every storm event greater than 10 inch (or L5 inches if in a Coastal County) Records of operation and maintenance will be kept in a known set location and will be available upon request Inspection activities shall be performed as follows Any problems that are found shall be repaired immediately BMP element Potential problem How I will remediate the problem The entire filter strip Trash/ debris is present Remove the trash/ debris system The flow splitter device The flow sphtter device is Unclog the conveyance and dispose (if applicable) clogged of any sediment off site The flow sphtter device is Make any necessary repairs or damaged replace if damage is too large for repair Form SWU401 Level Spreader Filter Strip Restored Riparian Buffer O &M Rev 3 Page 1 of 3 BMP element Potential problem How I will remediate the problem The swale and the level The swale is clogged with Remove the sediment and dispose lip sediment of it off site The level lip is cracked Repair or replace lip settled undercut eroded or otherwise damaged There is erosion around the Regrade the soil to create a berm end of the level spreader that that is higher than the level lip and shows stormwater has then plant a ground cover and bypassed it water until it is established Provide line and a one -time fertilizer application Trees or shrubs have begun Remove them to grow on the swale or lust downslo a of the level lip The bypass channel Areas of bare soil and /or Regrade the soil if necessary to erosive gullies have formed remove the gully and then reestablish proper erosion control Turf reinforcement is Study the site to see if a larger damaged or npap is rolling bypass channel is needed (enlarge if downhill necessary) After this reestablish the erosion control material The filter strip Grass is too short or too long Maintain grass at a height of (if applicable) approximately three to six inches Areas of bare soil and /or Regrade the soil if necessary to erosive gullies have formed remove the gully and then plant a ground cover and water until it is established Provide lime and a one -time fertilizer application Sediment is building up on Remove the sediment and the filter strip restabilize the soil with vegetation if necessary Provide lime and a one- time fertilizer application Plants are desiccated Provide additional irrigation and fertilizer as needed Plants are dead diseased or Determine the source of the dying problem soils hydrology disease etc Remedy the problem and replace plants Provide a one time fertilizer application Nuisance vegetation is Remove vegetation by hand if choking out desirable species possible If pesticide is used do not allow it to get into the receiving water The receiving water Erosion or other signs of Contact the NC Division of Water damage have occurred at the Quality local Regional Office or the outlet 401 Oversight Unit at 919 733 -1786 Form SWU401 Level Spreader Filter Strip Restored Ripanan Buffer O &M Rev 3 Page 2 of 3 Permit Number (to be provided by DWQ) 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 Project name The Woods at Umstead BMP drainage area number 1 Print name ',) U Title Address 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 e-- L a Notary Public for the State of C County of /n� {,J4 C� do hereby certify that tllC„ c.,.,K personally appeared before me this day o ar,Jc!24 a�t..2,.and acknowledge the due execution of the forgoing filter strip riparian buffer and/or level spreader maintenance requirements Witness my hand and official seal SEAL My commission expires /—�/— l/ Form SWU401 Level Spreader Filter Strip Restored Riparian Buffer O &M Rev 3 Page 3 of 3 JPtAESSq 0 a No, �.= ` N SEAL My commission expires /—�/— l/ Form SWU401 Level Spreader Filter Strip Restored Riparian Buffer O &M Rev 3 Page 3 of 3 m o= :0 .p D C7 M I S CD �c- a y � w : co j� 1 •' a�a CD � 1 C) O ' • I n o ° W z� IIII� III J O p p I z z� a3 -o ,,� c o x -o h do � Q � sQ vJ cr, - -. ozzo w z Z N fD N cn -4 (n DDI r<11 r O O 0 O o < -11111 N O -� �N G7 - Ali g Cn o IIII O. 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