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Home My WebLink About20150345 Ver 1_Stormwater Info_20150408City of Wilson- Merrimont Park Storm Water Calculations Located in: Wilson, North Carolina Prepared by: Green Engineering, PLLC PO Box 609 Wilson, NC 27894 `\l��N1�AROz ��`Q��r;Ssi6 � s - •a �F SE4L r': - • 022594 • W \WI SO \09144\Engmeenng\Stormwater Updated 0428-14 \Cover Sheet with TOC doc n[299uvL V� APR 0 B 2015 TABLE OF CONTENTS Description Stormwater • Site Narrative S1 • Storm Sewer Pipe Calculations S2 • Wet Detention Pond Calculations S3 • - Buoyancy Calculation S4 • Wet Detention Pond BMP Supplementary Forms S5 • Level Spreader BMP Supplementary Forms S6 • Neuse Nutrient Management Calculations S7 • Precipitation Data Sheets S8 Erosion & Sedimentation Control • Outlet Protection Calculations E1 • Ditch Liner Calculations E2 Appendix • USGS Map of Site • NRCS Soils Map of Site • Runoff /Drainage Maps W \ WIMO \09144\Engmeenng\Stotmwater - Updated 04 -28 14 \Cover Shea with TOC doc Merrimont Park Stormwater Project Page I SITE NARRATIVE Background - The Merrimont Park Stormwater Project is part of an overall goal and plan to help rehabilitate and reduce the stormwater impacts on the Hominy Swamp Creek, which is listed in as a 303(d) impaired stream by the State of NC. The park is an existing property owned by the City of Wilson and contains some playground equipment, a small building with restrooms and a picnic shelter. The remaining portion of the property is undeveloped. A paved basketball court was present at one time, but has been removed from the premises within the last three years The surrounding area is approximately 95% developed with residential homes directly adjacent to the park that has not been built out and is currently wooded future homes, but the project is not slated to start within the foreseeable future. Existing Project Area Information: Existing impervious breakdown- (onsite) • Property size: 7 85 acres • Existing Buildings /sidewalks. 1,430 sf or 0 0042 Ac • Percent Impervious. 0.05% Existing impervious beakdown (offsite flow into proposed BMP) • Total drainage area: 18 Ac • Existing Building /Roads: 8 66 Ac. • Percent Impervious: 4811% Water Basin: Neuse River Basin Flow to existing stream, There is a small area There are plans for 1 Piped flow along Buckingham Road to existing square culvert in Hominy Swamp Creek. 2 Overland flow from park grounds to Hominy Swamp Creek Flood Zone: The site is located within Zone X of the flood designations per FEMA Flood map 370270 3713 1, dated April 16, 2013. Soils: Several soil types are represented within the project area, the predominant soils being loamy sand (Goldsboro GoA) and sandy loam (Norfolk, NoA and Rains, Ra) A soils bores and report was performed in two locations within the BMP area by S &ME. The report is attached with this book in the appendix as reference. Rainfall Data: The rainfall data was obtained from the National Weather Service, Hydrometeorlogical Design Studies Center. The rain gauge Wilson 3 SW at Latitude 35 69390, Longitude -77 94560 at an elevation of 110 Green Engineering, PLLC July 25, 2015 PN: 09 -144 Merrimont Park Stormwater Project Page 2 feet was used for precipitation frequency estimates. The sheet is attached within the runoff calculations. Stormwater Drainage Patterns: Existina: The site flows in one direction, to the east of the property to the Hominy Swamp Creek, which is protected by the Neuse Buffer An existing street drainage system exists and currently connects to the creek through a direct discharge through the large culvert at the Buckingham Road creek crossing. The existing system at the point of discharge is currently a 24" RCP. Proposed The project is slated to capture the existing street drainage system and discharge the flow into the proposed BMP In addition, peak runoff from Hominy Swamp Creek is to be captured up to 5% of the total stream runoff and route through the proposed BMP The BMP outlet is proposed to be on the south eastern portion of the property by direct discharge from the BMP with 5 cfs being routed to a level spreader and vegetative filter strip The amount of flow through the filter strip is limited due to the location of the device In addition, as there is stream flow uptake into the BMP, the amount of cleaning required for the outflow is reduced. This was discussed and approved with DENR stormwater engineering group (via telephone on 7/11/14) Stormwater /Nutrient Management: The project is not required to meet stormwater management regulations as the surrounding areas are 95% developed, the existing flow is currently discharging directly into Hominy Swamp Creek and the design of the project includes receiving peak runoff from the existing creek into the proposed Wet Pond (BMP). However, for evaluation purposes, the design of the BMP meets the following requirements for the surrounding development only (excludes the peak runoff from the creek) The project was reviewed for stormwater management as far as meeting the following requirements • Pre vs Post development runoff (for the 10 year, 24 hour storm) • Nutrient Management to regulatory limits Based on the above, the following is the pre development vs post development runoff numbers for the various storms before routing through the BMPs and after routing through the BMPs designed onsite The total area reviewed includes the total offsite acreage of 18 acres and 5 8 acres of onsite that flows through the BMP pond. Runoff Comparisons (Phase 1): Description 1 -year 10 -year 25 -year 100 -year Pre development 35.87 113.03 158.66 246.35 Total Post Development 0.71 13.09 19.84 52.99 Green Engineering, PLLC July 25, 2015 PN: 09 -144 Merrimont Park Storm water Project Page 3 As shown, the post development flow is significantly less than the pre development flow and meets the stormwater requirements For nutrient management, the site drains into the Neuse River basin, however, as the site is a redevelopment of an existing site, the project does not need to meet the nutrient management Based on the proposed impervious for the project and the various phases of development, the following is the breakdown for the nutrient management for the various phases of development- Nutrient Management: Area Size (ac) Impervious Area (ac) Pervious Area (ac) Wooded Area (ac) Nutrient Management (lb /yr) TN Current TN Removed % Red Wet Pond 23.81 867 1514 0 201.97 505 25% Based on the nutrient management requirements for 30% reduction, this project does not meet the minimum, however, as it is a redevelopment, the reduction is better than the current nutrient management rate. Project Description: The following will be performed for the project: • Removal of any trees and playground items (to be placed back after completion of project) • Abandoning in place drainage pipes and sections that are not being used • Installation of new drainage system to proposed BMP. • Installation of Wet Detention Pond (BMP) Green Engineering, PLLC July 25, 2015 PN: 09 -144 STORM DRAINGE SCHEDULE 10YR MERRIMONT #09144 FROM TO DramageArea (ac) TotalArea (ac) InletTime (min) PipeTravel (min) Tc (min) RunoffCoeff (C) Inlet (m /hr) iSYs (in/hr) IncrCt I (cfs) TotalRunoff (cfs) VelAve (ft /s) LineSlope ( %) LmeSize (in) LmeLength (ft) PipeTravel (mm) InvertUp (ft) InvertDn (ft) Grnd /RlmElevUp (ft) EXISTING ALIGNMET NOT TO BE MODIFIED EX 209 EX 208 2 2 5 007 5 048 7 54 754 724 724 59 387 15 24 007 13743 1365 14048 EX 211 EX 210 185 185 5 011 5 048 754 754 67 67 546 167 15 36 011 1363 1357 1397 EX 207 EX 206 31 31 5 007 5 049 754 754 1145 1145 933 446 15 37 007 13939 13774 14204 EX 206 EX 208 11 42 5 027 51 05 754 752 415 1555 1268 06 15 206 027 13774 1365 14194 EX 208 EX 210 0 62 5 005 53 0 0 742 0 2249 1833 143 15 56 005 1365 1357 140 EX 210 EX 212 215 102 5 036 54 035 754 741 567 3458 1957 29 18 390 036 135 12368 1396 PROPOSED / MODIFIED ALIGNMENT EX 205 JB 6 31 31 5 004 5 049 754 754 1145 1145 933 095 15 25 004 12941 12917 13214 EX 218 JB 6 04 04 5 006 5 06 754 754 181 181 148 336 15 6 006 12936 12917 13185 JB 6 JIBS 0 35 5 036 51 0 0 752 0 1322 426 052 24 90 036 12842 12795 13153 JIBS JB4 0 35 5 031 54 0 0 74 0 1301 414 054 24 76 031 12795 12754 1322 JB 4 1B 3 0 35 5 146 57 0 0 729 0 1283 -- 408 0 54 24 345 146 127 12512 13513 EX 204 EX 203 08 08 5 026 5 054 754 754 326 326 184 074 18 28 026 12533 12512 12871 EX 203 JB 3 025 025 5 025 5 053 754 754 1 1 1 057 047 18 9 025 12516 12512 1289 1B 3 EX 212 0 455 5 022 72 0 0 686 0 1593 507 123 24 61 022 12502 12427 12845 EX 212 FES 1 3 1775 5 038 74 052 754 679 11 761 5811 834 05 36 167 038 1232 12236 12893 Hydraflow Table of Contents 09144 Wet Pond w Stream Overflow 2 gpw Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2015 by Autodesk, Inc v10 4 Monday, 04 / 6 / 2015 Watershed Model Schematic ................................................. ............................... 1 Hydrograph Return Period Recap ......................................... ............................... 2 1 -Year SummaryReport .................................................................................... ............................... 3 HydrographReports .............................................................................. ............................... 4 Hydrograph No 9, Reservoir, Route thru Pond 4 Pond Report - Wet Pond 5 10 - Year SummaryReport .................................................................................... ............................... 6 HydrographReports .............................................................................. ............................... 7 Hydrograph No. 9, Reservoir, Route thru Pond 7 25 - Year SummaryReport .................................................................................... ............................... 8 HydrographReports .............................................................................. ............................... 9 Hydrograph No 9, Reservoir, Route thru Pond 9 100 - Year SummaryReport .................................................................................. ............................... 10 HydrographReports ............................................................................ ............................... 11 Hydrograph No 9, Reservoir, Route thru Pond 11 OFReport .............................................................................. ............................... 12 1 Watershed Model Schemat �raflow!-Iydrographs Extension for AutoCADO Civil 31M2015 by Autodesk, Inc v104 dD dD 6) 8 0 e6 Legend Hytd Onain Description 1 SCS Runoff Main Lines 2 SCS Runoff Small Line 3 SCS Runoff Hominy Swamp Creek 4 Reach Hominy Swamp Creek 5 Diversionl Into Pond 6 Diversion2 Remain in Stream 7 SCS Runoff Park Overland Flow 8 Combine Sum of Hydrographs 9 Reservoir Route thru Pond Project 09144 Wet Pond w Stream Overflow 2 gpw Monday, 04 / 6 / 2015 Hydrograph Return Period Ry %C01 Rprographs Extension for AutoCAD® Civil 3D® 2015 by Autodesk, Inc v10 4 Hyd Hydrograph Inflow Peak Outflow (cfs) Hydrograph No type hyd(s) Description (origin) 1 -yr 2 -yr 3 -yr 5 -yr 10 -yr 25 -yr 50 -yr 100 -yr 1 SCS Runoff - -- 31 58 4472 0 707 6832 8952 12252 -- 18469 Main Lines 2 SCS Runoff -- - -- 0 445 0 630 0 010 0 962 1 261 1 726 - - - -- 2 601 Small Line 3 SCS Runoff --- - -- 22462 31916 9 947 48549 63447 86666 130521 Hominy Swamp Creek 4 Reach 3 22069 31424 9 694 47928 62758 85914 129634 Hominy Swamp Creek 5 Diversion1 4 11 03 1571 0 485 2396 31 38 4296 ---- 6482 Into Pond 6 Diversion2 4 20965 29853 9 210 45532 59620 81619 -- 231 52 Remain in Stream 7 SCS Runoff - - -- 2 354 5 147 0 000 1070 1616 2532 -- 4403 Park Overland Flow 8 Combine 1, 2, 5, 3587 5276 0 725 8424 11303 15866 -- 24635 Sum of Hydrographs 7 9 Reservoir 8 0 703 2 856 0 036 1012 1309 1984 -- 5299 Route thru Pond Prod file 09144 Wet Pond w Stream Overflow 2 gpw Monday, 04 / 6 / 2015 Hydrograph Summary Re Ky1d aflow Hydrographs Extension for AutoCAD® Civil 3130 2015 by Autodesk, Inc v10 4 Hyd No Hydrograph type (origin) Peak flow (cfs) Time interval (min) Time to Peak (min) Hyd volume (cult) Inflow hyd(s) Maximum elevation (ft) Total strge used (cult) Hydrograph Description 1 SCS Runoff 31 58 2 720 72,364 -- -- -- Main Lines 2 SCS Runoff 0 445 2 720 1,019 -- -- Small Line 3 SCS Runoff 22462 2 770 2,087,682 -- -- -- Hominy Swamp Creek 4 Reach 22069 2 778 2,087,678 3 — — Hominy Swamp Creek 5 Diversionl 11 03 2 778 104,384 4 -- -- Into Pond 6 Diversion2 20965 2 778 1,983,294 4 - -- -- Remain in Stream 7 SCS Runoff 2 354 2 718 6,544 - - - -- - - -- - -- Park Overland Flow 8 Combine 3587 2 720 184,311 1, 2, 5, - -- - - - -- Sum of Hydrographs 7 9 Reservoir 0 703 2 1448 150,094 8 12449 154,550 Route thru Pond 09144 Wet Pond w Stream Overflow 2 gpm, Return Period 1 Year Monday, 04 / 6 / 2015 Hydrograph Report 4 Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2015 by Autodesk, Inc v10 4 Monday, 04 / 6 / 2015 Hyd. No. 9 Route thru Pond Hydrograph type = Reservoir Peak discharge = 0 703 cfs Storm frequency = 1 yrs Time to peak = 24 13 hrs Time interval = 2 min Hyd volume = 150,094 cuft Inflow hyd No = 8 - Sum of Hydrographs Max Elevation = 124.49 ft Reservoir name = Wet Pond Max Storage = 154,550 cuft Storage Indication method used Route thru Pond Q (cfs) Hyd No 9 -- 1 Year Q (cfs) 4000 4000 3000 3000 2000 2000 1000 1000 000 0 00 0 10 20 30 40 50 60 70 80 90 100 Time (hrs) Hyd No 9 Hyd No 8 ELT= Total storage used = 154,550 cult Pond Report s Hydraflow Hydrographs Extension for AutoCAD® Civil 3DO 2015 by Autodesk, Inc v104 Monday, 04 / 6 / 2015 Pond No. 1 - Wet Pond [A] [B] Pond Data [PrfRsr] Rise (in) = 2400 Contours - User - defined contour areas Conic method used for volume calculation Beglning Elevation = 123 00 ft Stage / Storage Table Span (in) = 2400 500 Stage (ft) Elevation (ft) Contour area (sqft) Incr Storage (cuft) Total storage (cuft) 000 12300 92,691 0 0 100 12400 108,728 100,593 100,593 200 12500 113,512 111,100 211,693 300 12600 118,353 115,912 327,606 400 12700 123,250 120,781 448,387 500 12800 128,204 125,706 574,093 600 12900 150,000 138,946 713,039 Culvert / Orifice Structures [A] [B] [C] [PrfRsr] Rise (in) = 2400 500 600 000 Span (in) = 2400 500 2400 000 No Barrels = 1 1 3 0 Invert El (ft) = 12300 12300 12450 000 Length (ft) = 20000 067 067 000 Slope ( %) = 050 010 010 n/a N -Value = 013 013 013 n/a Orifice Coeff = 060 060 060 060 Multi -Stage = n/a Yes Yes No Stage (ft) 600 500 400 300 200 1 00 000 -' ' 00 200 Total Q Weir Structures [A] [B] [C] [D] Crest Len (ft) = 16 00 000 2000 000 Crest El (ft) = 12600 000 12710 000 Weir Coeff = 333 333 260 333 Weir Type = 1 — Broad — Multi -Stage = Yes No No No Exfil (in /hr) = 0 000 (by Wet area) TW Elev (ft) = 000 Note Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control Weir risers checked for orifice conditions (ic) and submergence (s) Stage / Discharge 400 600 800 1000 1200 1400 1600 Elev (ft) 12900 12800 12700 12600 12500 12400 --J- 123 00 1800 Discharge (cis) Hydrograph Summary Re pQy1d aflow Hydrographs Extension for AutoCADO Civil 3DO 2015 by Autodesk, Inc v104 Hyd No Hydrograph type (ongm) Peak flow (cfs) Time interval (min) Time to Peak (min) Hyd volume (cuft) Inflow hyd(s) Maximum elevation (ft) Total strge used (cult) Hydrograph Description 1 SCS Runoff 8952 2 718 205,718 -- -- - -- Main Lines 2 SCS Runoff 1 261 2 718 2,897 - - -- - - - -- - -- Small Line 3 SCS Runoff 63447 2 770 5,679,490 - - -- — — Hominy Swamp Creek 4 Reach 62758 2 774 5,679,491 3 — — Hominy Swamp Creek 5 Diversionl 31 38 2 774 283,974 4 — Into Pond 6 Diversion2 59620 2 774 5,395,516 4 — — Remain in Stream 7 SCS Runoff 1616 2 718 32,508 -- — - - -- Park Overland Flow 8 Combine 11303 2 718 525,098 1, 2, 5, - -- - -- Sum of Hydrographs 7 9 Reservoir 1309 2 872 486,103 8 12572 294,696 Route thru Pond 09144 Wet Pond w Stream Overflow 2 gp Return Period 10 Year Monday, 04 / 6 / 2015 Hydrograph Report 7 Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2015 by Autodesk, Inc. v10.4 Monday, 04 / 6 / 2015 Hyd. No. 9 Route thru Pond Hydrograph type = Reservoir Peak discharge = 13.09 cfs Storm frequency = 10 yrs Time to peak = 14.53 hrs Time interval = 2 min Hyd. volume = 486,103 cuft Inflow hyd. No. = 8 - Sum of Hydrographs Max. Elevation = 125.72 ft Reservoir name = Wet Pond Max. Storage = 294,696 cuft Storage Indication method used. Route thru Pond Q (cfs) Q (cfs) Hyd. No. 9 -- 10 Year 120.00 120.00 100.00 100.00 80.00 80.00 60.00 60.00 40.00 40.00 20.00 20.00 0.00 - 0.00 0 10 20 30 40 50 60 70 80 90 100 Time (hrs) Hyd No. 9 --- Hyd No. 8 [L= Total storage used = 294,696 cult Hydrograph Summary Re P9y'dlflow Hydrographs Extension for AutoCAD® Civil 3DOD 2015 by Autodesk, Inc. v10.4 Hyd. No. Hydrograph type (origin) Peak flow (cfa) Time interval (min) Time to Peak (min) Hyd. volume (cuff) Inflow hyd(s) Maximum elevation (ft) Total strge used (tuft) Hydrograph Description 1 SCS Runoff 122.52 2 718 284,201 — — — Main Lines 2 SCS Runoff 1.726 2 718 4,003 — — — Small Line 3 SCS Runoff 866.66 2 770 7,763,345 — — — Hominy Swamp Creek 4 Reach 859.14 2 774 7,763,343 3 — Hominy Swamp Creek 5 Diversionl 42.96 2 774 388,167 4 Into Pond 6 DiversIon2 816.19 2 774 7,375,177 4 — Remain in Stream 7 SCS Runoff 25.32 2 718 50,642 — Park Overland Flow 8 Combine 158.66 2 718 727,013 1, 2, 5, — — Sum of Hydmgraphs 7 9 Reservoir 19.84 2 850 687,335 8 126.58 397,485 Route thru Pond 09144 Wet Pond w Stream Overflow 2.9pw Return Period: 25 Year Monday, 04 / 6 / 2015 Hydrograph Report 9 Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2015 by Autodesk, Inc. v10.4 Monday, 04 / 6 / 2015 Hyd. No. 9 Route thru Pond Hydrograph type = Reservoir Peak discharge = 19.84 cfs Storm frequency = 25 yrs Time to peak = 14.17 hrs Time interval = 2 min Hyd. volume = 687,335 cuft Inflow hyd. No. = 8 - Sum of Hydrographs Max. Elevation = 126.58 ft Reservoir name = Wet Pond Max. Storage = 397,485 cuft Storage Indication method used. Q (cfs) 160.00 140.00 120.00 100.00 80.00 - -- _ 60.00 40.00 20.00 -- � —_ - 000 Route thru Pond Hyd. No. 9 -- 25 Year Q (cfs) 0 10 20 30 40 50 60 70 80 90 100 Time (hrs) Hyd No. 9 Hyd No. 8 �� Total storage used = 397,485 CA 10 Hyd rog ra p h Summary ReNyld flow Hydrographs Extension for AutoCAD® Civil 3136 2015 by Autodesk, Inc. A 0.4 Hyd. No. Hydrograph type (origin) Peak flow (cfs) Time interval (min) Time to Peak (min) Hyd. volume (cuft) Inflow hyd(s) Maximum elevation (ft) Total strge used (cult) Hydrogreph Description 1 SCS Runoff 184.69 2 718 436,584 — — — Main Lines 2 SCS Runoff 2.601 2 718 6,149 — — Small Line 3 SCS Runoff 1305.21 2 770 11,783,211 Hominy Swamp Creek 4 Reach 1296.34 2 774 11,783,211 3 — — Hominy Swamp Creek 5 Diversion) 64.82 2 774 589,160 4 — — Into Pond 6 Diversion2 1231.52 2 774 11,194,05 4 — — Remain in Stream 7 SCS Runoff 44.03 2 716 88,896 — — — Park Overland Flow 8 Combine 246.35 2 718 1,120,789 1, 2, 5, — — Sum of Hydrographs 7 9 Reservoir 52.99 2 816 1,080,076 8 127.77 545,014 Route thru Pond 09144 Wet Pond w Stream Overflow 2.gpw Return Period: 100 Year Monday, 04 / 6 / 2015 Storage Indication method used. Q (cfs) 280.00 240.00 160.00 120.00 .1 18 40.00 0.00 ' 0 6 Hyd No. 9 Route thru Pond Hyd. No. 9 - -100 Year 12 18 24 Hyd No. 8 Q (cfs) 280.00 240.00 200.00 160.00 120.00 40.00 0.00 30 36 42 48 54 60 Time (hrs) 1 ? ! 1 1 1 1 Total storage used = 545,014 cult 11 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2015 by Autodesk, Inc. v10.4 Monday, 04 / 6 / 2015 Hyd. No. 9 Route thru Pond Hydrograph type = Reservoir Peak discharge = 52.99 cfs Storm frequency = 100 yrs Time to peak = 13.60 hrs Time interval = 2 min Hyd. volume = 1,080,076 cuft Inflow hyd. No. = 8 - Sum of Hydrographs Max. Elevation = 127.77 ft Reservoir name = Wet Pond Max. Storage = 545,014 cuft Storage Indication method used. Q (cfs) 280.00 240.00 160.00 120.00 .1 18 40.00 0.00 ' 0 6 Hyd No. 9 Route thru Pond Hyd. No. 9 - -100 Year 12 18 24 Hyd No. 8 Q (cfs) 280.00 240.00 200.00 160.00 120.00 40.00 0.00 30 36 42 48 54 60 Time (hrs) 1 ? ! 1 1 1 1 Total storage used = 545,014 cult 12 Hydraflow Rainfall Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3136) 2015 by Autodesk, Inc. A 0.4 Monday, 04 / 6 / 2015 Retunn Period (Yre) Intensity -Duration- Frequency Equation Coefficients (FHA) B D E (WA) 1 61.9438 12.4000 0.8800 40 2 68.9322 12.4000 0.8646 1 3 0.0000 0.0000 0.0000 2.56 5 73.9364 12.8000 0.8351 1.63 10 75.6056 12.5000 0.8054 4.69 25 68.2812 11.3000 0.7469 2.45 50 62.9849 10.3000 0.7021 1.70 100 57.4404 9.3000 0.6575 0.00 File name: Wilson IDF.IDF Intensity = B / (Tc + D) "E Return Period Intensity Values (in/hr) (Yre) 5 min 10 15 20 25 30 35 40 45 50 55 60 1 5.01 4.02 3.36 2.90 2.56 2.29 2.08 1.90 1.75 1.63 1.52 1.43 2 5.83 4.69 3.94 3.41 3.01 2.70 2.45 2.25 2.08 1.93 1.81 1.70 3 0.00 0.00 0.00 0.00 0.00 0.00 .0.00 0.00 0.00 0.00 0.00 0.00 5 6.68 5.43 4.60 4.01 3.56 3.21 2.93 2.69 2.50 2.33 2.19 2.06 10 7.54 6.16 5.24 4.58 4.08 3.69 3.37 3.11 2.89 2.70 2.54 2.40 25 8.49 6.95 5.94 5.22 4.67 4.24 3.89 3.61 3.36 3.16 2.98 2.82 50 9.28 7.61 6.52 5.74 5.16 4.70 4.33 4.02 3.76 3.54 3.35 3.18 100 9.99 8.20 7.05 6.23 5.62 5.14 4.75 4.43 4.16 3.92 3.72 3.54 Tc = time in minutes. Values may exceed 60. Pracin. file name' W-\ WILSC)%09144kFnainearinat.Stermwater- Undated 04.29- 14\Wilsen_ncn Storm Rainfall Precipitation Table (in) Distribution 1 yr 2 yr 3 yr "r 10-yr 25-yr 50 yr 100 yr SCS 24 -hour 2.91 3.53 1.00 4.56 5.45 6.81 0.00 9.35 SCS 6-Hr 2.10 2.51 0.00 3.12 3.75 4.60 0.00 6.23 Huff -1st 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Huff -2nd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Huff -3rd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Huff -4th 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Huff -Indy 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Custom 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Outlet Structure Bouyancy Ca culations Fill in red numbers only! Green Engineering, PLLC Last revised 7/25/14 Project: Merrimont Park Stormwater Date: 04/06/15 Outlet Structure: Wet Pond Verification By: PWS Inside Length (ft) Inside Width (ft) Wall Thickness (in) Outlet Elevation Box Bottom Box Top IMH Bouyant Force 4 4 8 123.00 123.00 126.00 1 2,329.6 Ibs W (ft) 4 4 L (ft) W (ft) Outside Width (ft) 4 6,971.5 Ibs Base Bouyant Force Outside Length (ft) High Water Elev. 5.33 5.33 127.63 1,251.5 Ibs Base Thickness (in) Base Extension (in)l Base Length (ft) Base Width (ft) 6 6 1 6.33 6.33 H2O in Box? If Yes, Depth H2O' Holes in Box Dia Hole for Culvert Slab in Box Stone in Box Dry Soil Weight, 'Y (e.g. 110 pcf) 110 pcf 3 f L (ft) W (ft) 2 6 2 ft (subtract) L (ft) W (ft) 4 4 L (ft) W (ft) 4 4 1. Assumes density of concrete is 150 pcf or for brick at 140 pcf. 2. Assumes ground is saturated. 3. Excludes force due to gravity caused by extra concrete in moorbase. Force Down > Force Up No Additional Resistance N Weight of Saturated Soil, IYsat 47.6 pcf Conc Wt (pcf) Stone Wt (F 150 135 No. Holes 3 D (ft) 0 D (ft) 0.00 1.5 F.S Weight of Water 2,995.2 Ibs Base = 2,133.3 Ibs Box = 5,600.0 Ibs Holes = (3,600.0) Ibs Culvert= (157.1) Ibs Slab Wt.= - Ibs Stone Wt - Ibs Subtotal = 6,971.5 Ibs M. 4. Excludes resistance offered by soil friction on exterior wall of structure. 5. Excludes wt. of soil over extended base - no extended base proposed. 6. Excludes weight of grate /trash rack. 6,971.5 Ibs Down Actual Factor of Safety = WA NCDENR Project name Contact person Phone number Date Drainage area number Permit No STORMWATER MANAGEMENT PERMIT APPLICATION FORM 401 CERTIFICATION APPLICATION FORM WET DETENTION BASIN SUPPLEMENT This form must be filled out, punted and submitted The Required Items Checklist (Part ill) must be pnnted, filled out and submitted along with all of the required information 252 -23T -5365 70/2014' Y - DA -1 THRU DA-6 and DAAPark PROJECT (to be provided by DWQ) WWAA TF9pG O lqiiii� -c MADE "010 ,�k't"'�w',`- ��x��`�.ui*n�r�a*' 'W*�`, h�' ai„" de?n "'•�•;�;»4i;es:,it,t'.'�"�', 3 Site Characteristics Drainage area 1,036,728 f? Impervious area, post - development 378,660 if % impervious 3652 % Design rainfall depth 10 in Storage Volume Non -SA Waters Minimum volume required Volume provided Storage Volume SA Waters 15" runoff volume Pre - development 1 -yr, 24 -hr runoff Post - development 1 -yr, 24 -hr runoff Minimum volume required Volume provided Peak Flow Calculations Is the pre /post control of the lyr 24hr storm peak flow required? 1 -yr, 24 -hr rainfall depth Rational C, pre -development Rational C, post - development Rainfall intensity 1 -yr, 24 -hr storm Pre - development 1 -yr, 24 -hr peak flow Post - development 1 -yr, 24 -hr peak flow Pre /Post 1 -yr, 24 -hr peak flow control Elevations Temporary pool elevation Permanent pool elevation SHWT elevation (approx at the pens pool elevation) Top of 1Oft vegetated shelf elevation Bottom of 10ft vegetated shelf elevation Sediment deanout, top elevation (bottom of pond) Sediment cleanout, bottom elevation Sediment storage provided Is there additional volume stored above the state - required temp pool? Elevation of the top of the additional volume 32,719 ft3 155,665 ft3 OK, volume provided is equal to or in excess of volume required ft3 113 ft3 ft3 ft3 Y (Y or N) 29 in 035 (unitless) 0 54 ( unitless) 012 in/hr OK 100 ft3 /sec 154 ft3 /sec 054 ft3 /sec 12450 hsl 123 00 hsl hsl 123 50 hsl 12250 hsl Data not needed for calculation option #1, but OK if provided 11900 fmsl 11800 hsl Data not needed for calculation option #1, but OK if provided 100 It (Y or N) 124 5 hsl OK Form SW401 -Wet Detention Basin -Rev 9- 4/18/12 Parts 18 11 Design Summary, Page 1 of 2 Permit No (to be provided by DWQ) I 12 DES IQ NfIN,QR1YlAfiIQl+1 Surface Areas Area, temporary pool 111,094 ft2 Area REQUIRED, permanent pool 30,480 ft SAIDA ratio 12 94 (umtless) Area PROVIDED, permanent pool, Amn_pwl 92,691, W OK Area, bottom of 1Oft vegetated shelf, Abot_swff 72;770, e Area, sediment cleanout, top elevation (bottom of pond), Abotyefa 63,136 ft` Volumes Volume, temporary pool 155,665 ft3 OK Volume, permanent pool, Vcem_pw 361,639 ft" Volume, forebay (sum of forebays if more than one forebay) 50,460 ft3 Forebay % of permanent pool volume 140% % Insufficient forebay volume SAIDA Table Data Design TSS removal Coastal SAIDA Table Used? Mountain/Piedmont SAIDA Table Used? SAIDA ratio Average depth (used in SAIDA table) Calculation option 1 used? (See Figure 10 -2b) Volume, permanent pool, V,fm_pw Area provided, permanent pool, A,._pw Average depth calculated Average depth used in SAIDA, d.„ (Round to nearest 0 5ft) Calculation option 2 used? (See Figure 10 -2b) Area provided, permanent pool, Area, bottom of 1 Oft vegetated shelf, Apet shelf 90 % N (Y or N) Y (Y or N) 2 94 (unitless) Y . (Y or N) 361,639 ft' 92,691 ft 390 ft OK 4 0 ft OK N (Y or N) 92,691 le 72,770 ft` Area, sediment cleanout, top elevation (bottom of pond), Abot_p a 63,136 112 "Depth" (distance b/w bottom of 1 Oft shelf and top of sediment) 3 50 It Average depth calculated It Average depth used in SAIDA, d.„ (Round to down to nearest 0 5ft) ft Drawdown Calculations Drawdown through onfice? Diameter of onfice (if circular) Area of onfice (if- non - circular) Coefficient of discharge (CD) Driving head (H,) Drawdown through weir? Weir type Coefficient of discharge (CW) Length of weir (L) Driving head (H) Pre - development 1 -yr, 24 -hr peak flow Post - development 1 -yr, 24 -hr peak flow Storage volume discharge rate (through discharge onfice or weir) Storage volume drawdown time Additional Information Vegetated side slopes Vegetated shelf slope Vegetated shelf width Length of flowpath to width ratio Length to width ratio Trash rack for overflow & onfice? Freeboard provided Vegetated filter provided? Recorded drainage easement provided? Capures all runoff at ultimate build -out? Drain mechanism for maintenance or emergencies is Y (YorN) 5 00 in in 0 60 (unifless) 150 ft N (Y or N) ( unifless) (umtless) It ft 100 ft3 /sec 154 f3 /sec 0 69 ft3 /sec 2 56 days OK, draws down in 2 -5 days 3 1 OK 10 1 OK 100 It OK 1 1 Insufficient flow path to width ratio Must not short - circuit pond 15 1 OK Y (Y or N) OK 10 ft OK Y (Y or N) OK N (Y or N) Insufficient Recorded drainage easement required Y (Y or N) OK Manual Pump Out Form SW401 -Wet Detention Basin -Rev 9- 4/18/12 Parts I & 11 Design Summary Page 2 of 2 AMOVA NCDENR STORMWATER MANAGEMENT PERMIT APPLICATION FORM 401 CERTIFICATION APPLICATION FORM LEVEL SPREADER - VEGETATED FILTER STRIP (LS -VFS) SUPPLEMENT This form must be completely filled out, printed, initialed, and submitted Project name Contact name Phone number Date Drainage area number The purpose of the LS -VFS Stormwater enters LS -VFS from Type of VFS Explanation of any "Other" responses above If 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, 1 0 -yr storm Peak flow from the 10 -yr storm Design storm Maximum amount of flow directed to the LS -VFS Is a flow bypass system going to be used? Explanation 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 used? Explanation of any 'Other" responses above 252 - 237;5365 July 25,2014 1 A BMP - Protected riparian buffer (slope < 5 %) fe Do not complete this section of the foam fe Do not complete this section of the form % Do not complete this section of the form 5 Do not complete this section of the form cis Do not complete this section of the form min Do not complete this section of the form in/hr Do not complete this section of the form cfs Do not complete this section of the form i u-year storm ��OF YJATF9oL h > ti D r cts Do not complete this section of the form (Y or N) Do not complete this section of the form System is designed to 5 efs due to site constraints as well as site r. aocepbng inflow from existing creek during peak flows Wet detention pond 5 cis 1309 cis 2 cfs 5 cis y (Y or N) Form SW401 - LS -VFS - 29June2012 - Rev 10 page 1 of 3 LS -VFS Design Forebay surface area Depth of forebay at stormwater entry point Depth of forebay at stormwater exit point Feet of level lip needed per cfs Computed minimum length of the level lip needed Length of level lip provided Width of VFS Elevation at downslope base of level lip Elevation at the end of the VFS that is farthest from the LS Slope (from level lip to the end of the VFS) Are 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 engineered flow splitting device? Dimensions of the channel (see diagram below) M B W y (flow depth for 10 -year stone) freeboard (during the 10 -year storm) Peak velocity in the channel during the 10 -yr stone 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 0 sq It No forebay is required ft in ft 100 in 361 50 ft/cfs 250 ft The flow is too high for a 100 -foot level spreader 50 ft Level spreader is too short to handle the flow 30 , ft Width of VFS is not adegate 12200 fmsl 12140 fmsl 200 % In (Y or N) OK n (Y or N) y (Y or N) y (Y or N) Please provide plan details of flow splatter & supporting ceics ,300 ft 200 ft 6l)0 ft ,0'50 ft 100 ft 361 ft/sec Rip -rap n (Y or N) y (Y or N) The LS design is'10 ft/s per its and VS is 30' wide per discussion with NCDENR stormwater engineer, dated,7 /11/14 W B J Form SW401 - LS -VFS - 29June2012 - Rev 10 page 2 of 3 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 Initial in the space provided to indicate the following design requirements have been met If the applicant has designated an agent, the agent may initial below If a requirement has not been met, attach justification. Requried Item- 1 Plans (1" - 50' or larger) of the entire site showing Design at ultimate build -out, Off -site drainage (ff applicable), Delineated drainage basins (include Rational C coefficient per basin), Forebay (d applicable), High flow bypass system, Maintenance access, Proposed drainage easement and public right of way (ROW), and Boundaries of drainage easement 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 lip and top of stream bank, Proposed drainage easement, and Design at ultimate build -out Section view of the level spreader (1" = 20' or larger) showing Underdrain system (if applicable), Level lip, Upslope channel, and Downslope filter fabric 4 Plan details of the flow splitting device and supporting calculations (ff applicable) 5 A construction sequence that shows how the level spreader will be protected from sediment until the entire drainage area is stabilized If a non -engineered VFS is being used, then provide a photograph of the VFS showing that no draws are present 7 The supporting calculations 8 A copy of the signed and notarized operation and maintenance (O&M) agreement Initials Page or plan sheet number and any notes- Form SW401 - LS -VFS - 29June2012 - Rev 10 page 3 of 3 METHOD 1 Residential Development Footprints Not Shown Type of Land Cover Site Area (Ac) TN Export Coeff TN Export by Land Use (lbslyr) TN Export From Site (lbslac /yr) Open Space 0 06 0 _ Managed Open space 0 1 2 0 Right of Way 0 11 0� Lots 0 40 0 lbs /yr Totals 01 0 METHOD 2 Developments with Footprints Shown Open Space i 01 0 6I 01 Managed Open Space 15 141 121 18 1681 Impervious surfaces 1 8671 21 2 183 804 Totals 23811 851 201 972 Ibs /yr I_ �— I 1- Total from Methods 1 and 2 23811 201 972 Ibs /yr _ Nutrient Removal Rate Wet Det Pond 25% Tn ITotal Efficency Tn %= 25 %1 I _ Total Tn Removed = `50`5 LBSNR I I I I eclpttatfon rrequency Uata server http //hdsc nws noaa gov/hdsc /pfds /pfds _pnntpage html ?lat =35 6939 &1 NOAA Atlas 14, Volume 2, Version 3 Location name Wilson, North Carolina, US' Latitude 35 6939 °, Longitude- -77 9456° (D Elevation 111 ft' t source Google Maps POINT PRECIPITATION FREQUENCY ESTIMATES G M Bonnin, D Martin, B Lin, T Parcybok MYekta and D ILley NOAH, National Weather Service, Silver Spring, Maryland PF tabular I PF graphical I Maps & aerials PF tabular PDS -based point precipitation frequency estimates with 90% confidence intervals (in inches /hour)' Average recurrence interval (years) FDuratio�,FFl-F- ' 1 I ` I � 10 25 I 50 100 200 -500,,F 1000 5-min 502 (455-553) 584 f (5 32 6 43) 668 (6 OL 36) F 755 (6 85 -8 32) F-8 1 (7 68 -9 34) F 928 (8 34 -10 2) F 100 (8 96 -11 0) F 107 , (9 54_11 8) 116 (10 2 -12 8) 1 124 (108-137) 10-min 4 00 4 67 5 35 604 6 77 7 39 7 96 8 51 917 9 76 (3 84-4 42) (4 25 -5 14) (4 87 -5 89) (5 48 -665) J (612-744) (6 64 -8 12) (7 12 -8 74) (7 56 -9 35) I , (8 08 -10 1) (852-108) Fl 5-min , 334 392 I 451 509 572 624 671 715 70 F(6787848) 817 (3 03 -3 68) (3 56 4 31) ; (4 10 4 97) (4 62 -5 61) i (5 17 -6 29) (5 61 -6 85) (6 00 -7 37) , (6 36 -7 86) _ - j (713-902) 229 2 70 321 3 69 4 24 4 70 514 5 57 612 ! 6 61 30-min (2 08 -2 52) (2 46 -2 98) (2 91 -3 53) (3 35-406) (3 83 -4 66) I (4 22 -5 16) F(4 59 -5 64) , (4 95-6 12) I (5 39-0 75) (577-730) 143 1 7 2 06 240 I 2 82 318 3 54 3 90 9 483 60-min �1 29 -1 57) L154-10 87) (1 87 -2 26) ; (2 18_2 65) (2 55 -3 10) ; (2 86 -3 50) (3 16 -3 89) (3 47-4 29) 78�7, ( 84) (4 21 -5 33) 0 828 , 0 989 ' 122 146 i 176 204 232 263 3 O6 ; 3 46 i 2 -hr , (0 750 -0 914) (0 900 -1 09) ; (1 11 -134) 11 (1132-161) I (159-194) 11 (183-2 24) (2 07 -2 54) (2 33 -2 88) (2 68 -3 36) 11 (3 00 -3 80) 0 584 1 F 0 700 0 867 ; 104 I 1 27 1 49 1 72 1 97 2 32 .1 2 66 3 -hr (0 532-0 646), (0 639-0 772)' (0 791 -0 957), to 948-1 15) (1 15-140) (1 34-164) 5211 88) I (1 73 2 15) (202-255) ! (229-292) ; 6-hr 0 350 ! (0 320-0 386). 0 419 (0 383-0 461) 0 520 (0 475 -0 571), 0 626 (0 570 -0 687), 0 768 (0 694 -0 840) 0 900 (0 808 -0 984) 104 (0 925 -1 14) 1 20 (105-130) 1 42 (1 24-15 163 (1 40-1 78) FI2 -hr J 0204 1 (0 187-0 224) 0 244 1 (0 224 -0 267) 0 304 (0 279 -0 333), 0 368 j (0 336 -0 403) OA55 (0 412 -0 495)'1(0 0 537 482 -0 583), 0 624 1(0 555 -0 677) 0 723 (0 635 -0 783)1, 0 867 1(0 749-0 938) 1 00 (0 855-109) , F,hr 0121 0147 ' 0190 F-6 —227F —6284 6 333 o 389 0 453 0 —5561, 0 635 (0 112-0 132) (0 136-0 160) (0 176_0 206) (0 210_0 246); (0 259 -0 308) (0 302-0 362)' (0349 -0 423)'[(0 400-0 494)11(q 476-0 604) (0 540 -0 701) 2 -day 0 070 F 0 085 0109 0129 0160 0187 0 217 0 251 0 302 0346 1 (0 065-0 076)'1(0 079-0 092) (0 101 -0 118); (0119 -0 140) j (0 146 -0 174), (0 170 -0 203)'1(0 195 -0 237) (0 222-0 275)1(0 262-0 334)'1(0 295 -0 386) 3-day 0 050 I (0 046-0 054) 0 060 (0 056 -0 065), 0 077 (0 071 -0 083)'1(0 F 0 091 084 -0 098) T 0111 (0 102-0121),1(0 0129 118 -0 141) F 0149 (0 134 -0 163) F 0 172 (0152-0 187) 0 205 (0 178-0 226) 0 233 (0 200 -0 259) 4-day 0 040 (0 037-0 043)'1(0 0048 044-0 052)' 0 060 (0 056 -0 065) 0 071 (0 066-0 077) 0 087 (0 080 -0 094) 0101 (0 092-0 109) 0115 (0 104_0 126)' 0132 (0117 -0 144), 0156 (0 137-0 172)1 0177 (0 153 -0 196)_, 002 0 032 0 040 0 047 j 0 056 0 064 0 073 0 083 0 097 0108 F 7-day (0 025 -0 029),1(0 030 -0 034) (0 037 -0 043) (0 043 -0 050), (0 052 -0 0611), 1(0 059 -0 070),1(0 066 -0 080) (0 074-0 090), (0 085-0 106) (0 094 -0 119), 10-dey 0 021 0 025 0 031 00 36 00 43 1 0 04 0 049 0 056 0 062 1 0072 0080 1(0 020 -0 023) (0 024 -0 027) (0 029 -0 034) (0 034 -0 039) (0040 -0 047) (0 045-0 053), (0 051 -0 060) (0 056-0 068); (0 064-0 079)' (0 071 -0 088)' 20 -day _ 0 014 (0 013.0 015)' 0 017 (0 016 -0 01_8) 0 021 0 024 (0 019.0 022) (0 022 -0 025) 0 028 (0 026.0 030), 0 031 (0 029-0 03.4_) 0 035 (0 032 -0 038) 0 039 (0 035 -0 042) 1(0_040-0 0 044 I 048)!1(0 0049 043 -0 053) 3(; ay 0 012 (0 011-0 013) 0 014 1 (0 013 -0 015) 0 017 0 019 (0 016 -0 018)'1(0 018 -0 020),1(0 0 022 021 -0 023)'1(0 0 024 i 023-0 026), 0 027 (0 025 -0 029)1 0 030 (0 027-0 032)i 0 033 F(O 030-0 036) 0 036 (0 032 -0 039) [4t 7�[ 0 010 0 00 9 -0 011). 0 012 (0 011-0 012),1(0 0 014 013-0 015)] 0 016 I (0 015 -0 017)' 0 018 (0 017 -0 019)] 0 020 (0 018 -0 021)l 0 022 (0 020_0 023):1(0 0 024 022 -0 02q)',11(0 0 026 024-0 028)j 0 028 � (0 026_0 031)' F 6aday,,F 0 009 F 0 011 F 0 012 I 0 01a F 0 016 F 0 017 F 0 018 F 0 020 F 0 022 0 023 1(0008-0009),1(0010-0011);1(0012-0013)1(0013-0014)1 1(0015-0016) (0 016 -0 018)' (0 017 -0 020)' (0 018-0 021)1(0 020-0 023)! (0 021 -0 025)' 1 Precipitation frequency (PF) estimates In this table are based on frequency analysis of partial duration series (PDS) Numbers In parenthesis are PF estimates at lower and upper bounds of the 90% confidence Interval The probability that precipitation frequency estimates (for ' a given duration and average recurrence Interval) will be greater than the upper bound (or less than the lower bound) Is 5% Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values Please refer to NOAA Atlas 14 document for more Information Back to Too PF graphical f4 5/13/2014 11 12 AM .eciprtation Prequency llata Server 100.000 t 10.000 c 1.000 c r- .2 0.100 M a V FU 0 -010 http: // hdsc. nws. noaa. gov /hdsc /pfds /pfds _printpage.html ?lat= 35.6939 &1... PDS -based intensity- duration - frequency (IDF) curves Latitude: 35.69391, Longitude: - 77.9456° .. . -- -. ... . 0 001 :ton Sa6err� .� - ..:,:. Hr h ' Greegsburo g Pointy " ^t D f pty .-, '4, • Ra *birth: t Carolina 1 S- rw . co►lwe0 6feenY , 11 Corxord fd - 30~ _C G G G G �. L L T ?,T T- T>, >, T E E E E E rLV N a '0 'o v 'v v v v-y v If1 o V1 0 n $ N A rvl n o 0 0 Q .-1 Duration r-r N rn W 100.000 10.000 c 2:1 1.000 v c C 0 0.100 m La- u N 0.010 I I I 0 -001 1 1 1 1 1 1 1 1 1 r 1 2 5 10 25 50 100 200 500 1000 Average recurrence interval (years) NOAA Atlas 14, Volume 2, Version 3 Created (GMT): Tue May 13 15:10:36 2014 Back to To Maps & aerials Small scale terrain ,., 7. T • "Caen,/ m • ."1 . J :ton Sa6err� .� - ..:,:. Hr h ' Greegsburo g Pointy " ^t D f pty .-, '4, • Ra *birth: t Carolina 1 S- rw . co►lwe0 6feenY , 11 Corxord fd - 30~ 7-day rl Charlotte' Fayettevlt4e r 4, IGns1o�+ rr1lr► t 9 IRocic'H1l1 QOOay Average recurrence interval (years) — 1 2 — 5 10 — 25 — so 1D0 200 500 IODD Duration – 6rrtr — 2-day — 104M — ] -day 1 S- rw -- 4.4" 30~ 7-day — 60 -ffwl — 10-day -` 2-ft QOOay — 64W — 4"* — 124W — 00-d" 244M aim, k,.: i�¢6e�J iwiiW dW&UA jSeagle f4 5/13/2014 11:12 AM _.ecipitation Frequency Data Server f4 http: // hdsc. nws. noaa. gov /hdsc /pfds /pfds _printpage.html ?lat = 35.693 9 &1... Large scale terrain V, Z Mute ti'ws= ,wo yT - - 2b4 7697 2 km Map d8bp&AMi*Peooe Large scale map _ Nrugrnt!a� (471 ,sec• r' � - Fr{Uf!utr C°"��ti Mlfjµu n -1 • I i 16971 2 Map d8bocWCW3eo4e Back to Too 5/13/2014 11:12 AM ■! 303 Goldsboro St OUTLET PROTECTION CALCULATIONS �`�11 Wilson, NC 27894 252.237.5365 Engineering 252.243.7489 (fax) Outlet ID: FES #3 at 24" RCP Storm Structure Project.. Merrimont Park Stormwater Project Date: 4/6/2015 Designer: pws Q 10 = 8.09 cfs V = 3.61 fps do = 24 inches La = 10 feet d50 = 0.3 feet d50 Stone Size (in) NCDOT Class Gravel Rip Rap 1 Class A 2 -6" 2 Class B 6 to 15" Rock Rip Rap 6 Class 1 9 to 12" 9 Class II 15 to 18" 12 15 18 21 24 dmax = d50 x 1.5 dmax = stone size for outlet protection depth = dmax x 1.5 Y Place Class A Over Filter Fabric Depth = 9 'e inches feet 9 inches 4/6/20153:28 PM Outlet Protection or 09144 een 303 Goldsboro St Engineering 252.243.7489 (fax) 0.612 MIN 0.27 psf S = 0.0050 ft/ft D = 0.87 ft Q = 8.09 cfs L = 132 ft V = 3.60 fps TT in Channel = Tractive Force= Wilson, NC 27894 252.237.5365 No.: Project: Designer: Sc = 0.0083 ft/ft Dc = 0.85 ft VC = 3.71 fps (n = 0.02 ) DITCH LINER CALCULATIONS D -1 JJN: 109 -144 Merrimont Park Stormwater 10/13/14 VEE Channel Bottom Width = 0 ft Left Side Slope = 3 :1 Right Side Slope = 3 :1 A temporary lining is needed. Use Rip Rap, d50 =9 inches Install the Rip Rap Liner in accordance with the details shown in the drawings. Place Rip Rap over a layer of Mirafi 140N or equal filter fabric. Hand place Rip Rap to fit the channel shape. 0.87 ft <3e043 I 1 0.85 ft � Vee Ditch w /Lining ft I� ft ft ft 1 1 i ft ft ft ft ft N W—< e S 200 cu Feet 3 o M, 0 N (O N m 0 E r X 00 O L t✓ D Legend Proposed Pond Merrimont Park so OUAD MA P L wVP. 1 cen ajEngineering 7 1 303 GOLDSBORO ST WILSON, NC 27893 252- 237 -5365 www.greenengineering.com 7 � cen 2 00 Engineerk Feet 3 303 GOLDSBORO ST cl WILSON, NC 27893 •. �� . r 252- 237 -5365 C) www.greenengineering.com X LO E � - ,s.}'T_• 4:. O CL 7' - Qi m CIO O ^' - 0 `c.. ••� >J r Legend �sx' Proposed Pond Merrimont Park +`• M. SD�� IVAP � + t USGS TOPOGRAPHICAL MAP MERRIMONT PARK STORMWATER PROJECT LAT: 35.75647, LONG: - 77.94243 16 s • r • ' cr' 4A is ' ' + d � stxnure�an(f �; •ti c,h iL s r^' EX. MERRIMONT i PARK � =O + t 1 1 I C) * rn m zz, FOREST HILLS �• lr ; LS ROAD � . f . • + r If ' 1 r � � i 9EIngineerling f.i.° ` /,,fir d I' /' t .*' , ��o �j .+► f�, ,,,`CA . `R y� �. .,p,�� '�� :Fad i ` f[ r ai •� 't AMM 147 o, IW 1 � • e c i �� ' �� -.�� - � da EX. MERRIMONT PARK ��' i