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Home My WebLink AboutNHC Stormwater Design Narrative_IFP R1 GE Aerospace – North Gate Improvements Project No. 6260230100 WSP April 4, 2025 Page i GE AEROSPACE – NORTH GATE IMPROVEMENTS STORMWATER NARRATIVE GE AVIATION WILMINGTON, LLC ISSUED FOR PERMIT WSP PROJECT NO.: 6260230100 DATE: APRIL 4, 2025 WSP USA, INC. 5710 OLEANDER DRIVE, SUITE 110 WILMINGTON, NC 28403 T: (910) 452-1185 WSP.COM WSP USA, Inc 5710 Oleander Drive, Suite 110 Wilmington, North Carolina 28403 Tel (910) 452-1185 WSP www.wsp.com April 4, 2025 Licensure: NC Engineering F-0165 Page ii April 4, 2025 Prepared By: WSP USA, Inc. 5710 Oleander Drive. Wilmington, NC 28403 Prepared For: GE Aviation Wilmington, LLC 3905 Castle Hayne Road Castle Hayne, NC 28429 WSP Project No.: 6260230100 Ryan Spiker, PE Senior Civil Engineer GE Aerospace – North Gate Improvements WSP Project No. 6260230100 Page iii TABLE OF CONTENTS STORMWATER DESIGN NARRATIVE .................... 1 BACKGROUND INFORMATION ........................................................ 1 PROJECT DESCRIPTION .................................................................... 1 STORMWATER DESIGN ...................................................................... 1 HYDROLOGIC ANALYSIS (PRE/ POST DEVELOPMENT) ........2 HYDRAULIC ANALYSIS ......................................................................2 PERMIT COORDINATION ...................................................................3 APPENDICES APPENDIX A – SITE LOCATION MAP APPENDIX B – USGS MAP APPENDIX C – USDA SOIL SURVEY MAP APPENDIX D – DRAINAGE AREA MAPS APPENDIX E – CALCULATIONS APPENDIX F – NOAA ATLAS 14 RAINFALL DATA GE Aerospace – North Gate Improvements WSP Project No. 6260230100 Page 1 STORMWATER DESIGN NARRATIVE BACKGROUND INFORMATION As part of the land separation between GE Aerospace and GE Vernova, GE Aerospace plans to redevelop the existing north gate entrance of their facility to enhance traffic flow and comply with the requirements as part of the separation. The redevelopment will include the creation of a dedicated truck lane, a new visitor parking lot, and the relocation of the existing key card reader closer to the guard house. The project is located at 3905 Castle Hayne Road in New Hanover County, North Carolina. It is located 0.32 miles north of the Castle Hayne Road and Interstate I-140 overpass. Access to the site will be via the existing site entrance from Castle Hayne Road. The proposed improvements as shown in these drawings will further support the compliance requirements between GE Aerospace and GE Vernova. The limits of disturbance for the project area falls entirely within Industrial District (I-2) zoning according to New Hanover County Geographical Information Systems (GIS). A copy of the United States Geological Survey (USGS) map is attached (Appendix B) indicating the project vicinity and general drainage patterns in the area. The United States Department of Agriculture (USDA) soil survey map (Appendix C) indicates the underlying soils within the project area are predominantly Onslow Loamy Fine Sand (On) and Urban Land (Ur). The Hydraulic Soil Group Classification of Onslow Loamy Fine Sand is A. Stormwater runoff from the site discharges to an existing NPDES permitted outfall 15 (NPDES Permit NCS000617) prior to discharging to Prince George Creek (Stream Index: 18-74-53, water surface classification C, Sw), which is located within the Cape Fear River Basin. PROJECT DESCRIPTION The proposed improvements are consistent with most entrance gate improvements at industrial sites. The intent of this project is to redevelop the existing north gate entrance, parking lot and add a dedicated truck lane to improve the traffic conditions entering and exiting the site. The project is located at GE Aerospace in New Hanover County, North Carolina. • Total Proposed Limits of Disturbance: 1.29 acres STORMWATER DESIGN The projects proposed grading plan will utilize existing drainage patterns with minimum slopes and promote sheet flow except where piping to the outfall is necessary. To attenuate peak discharge from the site in the proposed condition, a swale is proposed to extend the time of concentration, and a permanent rock check dam is proposed approximately half-way down the swale. Prior to discharging into the existing outfall, riprap outlet protection will be installed to dissipate the velocity to ensure non-erodible velocities are achieved. The outfall drains to a potential intermittent stream (Steam H as defined in SAW-2024-01272 (GE)), which flows north within the GE Aerospace property before reaching the permitted NPDES #15 outfall and ultimately discharging to Prince George Creek. GE Aerospace – North Gate Improvements WSP Project No. 6260230100 Page 2 HYDROLOGIC ANALYSIS (PRE/ POST DEVELOPMENT) Drainage area delineation (Appendix D) was based on topographic field survey. Two Points of Analysis (POA) were chosen for pre and post development peak discharge comparison. Stormwater runoff calculations for this analysis were based on Soil Conservation Service (SCS) TR-55 runoff curve numbers (CN) for impervious surface for all BUA within the project limits. Stormwater hydrographs and routing were modeled using Hydraflow Hydrographs Extension for Autodesk® Civil 3D® to model pre and post development conditions for different return event scenarios (Table 1). Table 1 – Routing Summary Peak Discharge (ft3/s) at Point of Analysis POA Return Event 2-yr 10-yr 25-yr 50-yr 100-YR POA-01 Pre-Development 1.47 2.77 3.73 4.56 5.55 Post-Development 1.56 2.81 3.71 4.49 5.41 POA-02 Pre-Development 0.87 1.64 2.20 2.70 3.28 Post-Development 0.99 1.77 2.33 2.82 3.40 TOTALS (ROUTED) Pre-Development 2.33 4.41 5.93 7.26 8.83 Post-Development* 2.13 3.91 5.22 6.35 7.70 *Post-Development Peak Discharge accounts for POA-01 runoff routed through the proposed swale. HYDRAULIC ANALYSIS Peak runoff flow rates for each drainage area was calculated using the Rational Method to design and evaluate both the proposed swale and pipe system. The Rational Method estimates the peak discharge (Q) in cubic feet per second (cfs) as a function of drainage area (A) in acres, mean rainfall intensity (I) in inches per hour for a duration equal to the time of concentration (Tc), a dimensionless runoff coefficient (C) and a dimensionless runoff frequency factor (Cf) as determined by the NHC Stormwater Design Manual. The time of concentration (Tc) for a drainage area generally consists of sheet flow, shallow concentrated flow and channel flow. Sheet flow was assumed to be no greater than 100 feet of the flow path. NOAA Atlas 14, Volume 2, Version 3, Point Precipitation Frequency Estimates (Appendix F) was used to obtain the different storm event intensities for the varying Tc. The proposed swale was designed for the 25-year storm event and evaluated during the 100-year storm event. The results for the proposed swale in Appendix E show the swale safely conveys the 25-year storm event. The proposed pipe system was designed for the 25-year storm event and evaluated during the 100-year storm event. The proposed pipe system was modeled using Bently StormCAD for Autodesk Civil 3D 2020. The 25-year StormCAD results (Appendix E) for the proposed system shows the hydraulic grade line (HGL) stays within the rim elevation of the proposed drop inlet and does not exceed the height of the proposed swale. Inlet spread on the proposed drop inlet was analyzed using a 4 inch/hour event and model results (Appendix E) indicate the spread (2.3-ft spread at 1.8-inch depth) meets the allowable spread as determined by NHC Stormwater Design Manual. GE Aerospace – North Gate Improvements WSP Project No. 6260230100 Page 3 PERMIT COORDINATION On-going permits for this project include the following: • New Hanover County (NHC) Major Site Plan o COAST Number: SITECN-25-000062, submitted 02/26/2025 • NHC Tree Removal o COAST Number: TR-25-000061, submitted 02/26/2025 • NHC Erosion and Sediment Control o COAST Number: LNDP-25-00239, submitted 02/28/2025 • NCDOT Driveway Permit Although GE Aerospace holds multiple State Stormwater Permits through North Carolina Department of Environmental Quality (NCDEQ), this project will elect to open a new Stormwater Permit through the State due to exceeding the 10,000 square feet of new proposed impervious. At this time, the permitting package has not been submitted to the State but will be sent following NHC Stormwater approval. APPENDIX A SITE LOCATION MAP APPENDIX B USGS MAP APPENDIX C USDA SOIL SURVEY MAP APPENDIX D DRAINAGE AREA MAP LOD LOD L O D LOD LO D LOD PROJECT AREA CA S T L E H A Y N E R D CENTENNIAL DR HERMITAGE RD HWY-1 4 0 GE AEROSPACE FACILITY TOTAL DA: 496.18 ACRES ON-SITE DA: 89.41 ACRES (WITHIN GE AEROSPACE BOUNDARY) OFF-SITE DA:406.77 ACRES (INLCUDING GE VERNOVA) CH A I R R D GLADIOLUS RD SLED G E R D POTENTIAL INTERMITTENT STREAM (H) POTENTIAL PERENNIAL STREAM (I) DRAINS TO PRINCE GEORGE CREEK APPROXIMATE LOCATION OF EXISTING NPDES OUTFALL 15 AND 15i 20 20 40 4040 40 40 40 40 40 40 4 0 404040 ISSUE/REVISION DESCRIPTIONYREVDM DR.ENG. SCALE HORIZONTAL: SCALE VERTICAL: SHEET TITLE: PROJECT: DATE: SHEET NO. REVISION NO. PROJECT NO.: APPROVED BY: RS D 04.04.2025 GE AEROSPACE NORTH GATE IMPROVEMENTS WILMINGTON, NORTH CAROLINA 6260230100 DRAWN BY: CP REVIEWED BY: RS SEAL:SEAL: WSP USA INC. 5710 OLEANDER DRIVE, SUITE 110 WILMINGTON, NC 28403 TEL:(910) 452-1185 LICENSURE: NC ENG: F-0165 NC GEOLOGY: C-557 ENGINEER:CLIENT: 3905 CASTLE HAYNE RD. CASTLE HAYNE, NC 28429 FOR REVIEW ONLY - NOT FOR CONSTRUCTION FOR REVIEW ONLY - NOT FOR CONSTRUCTION EX. 1 N/A 1"=20' 0 SCALE: 1"=400' (Horiz.) 800'400'400' LEGEND: DRAINAGE AREA BOUNDARY SURVEYED WETLANDS SURVEYED STREAMS PROPERTY LINE LIMITS OF DISTURBANCELODLOD DRAINAGE AREA MAP - EXHIBIT 1 9039927.43 9264128.47S.MH 9264227.60S.MH 92801 N: 210305.828' E: 2324675.097' EL:27.950' TRV FLY 92802 N: 210301.245' E: 2324835.038' EL:27.658' TRV FLY 92803 N: 209994.221' E: 2324893.750' EL:27.924' TRV FLY 9310227.30BUSH 9310327.05BUSH 9310427.06BUSH 9310527.16BUSH 9312028.82SP 9313529.03LSA 9313628.81LSA 9313728.89LSA 9313828.96LSA 9323429.52LSA 9323529.75LSA 9323629.65LSA 9323729.81LSA 9327529.67STMP X X X X X X X X X X X X X 22" OAK 16" OAK 30" OAK 18" SYCAMORE 18" GUM 36" OAK 26" SYCAMORE 30" SYCAMORE 20" MAGNOLIA 26" MAGNOLIA 20" GUM 32" PINE 24" GUM 24" OAK 8" OAK 26" OAK 28" OAK 32" OAK 10" SYCAMORE 8" SYCAMORE THOM A S E D I S O N A V E N U E CA S T L E H A Y N E R O A D 4 - 4 8 " C M P ' S 30 28 2 7 2728 2 6 29 2020 251919 2 1 2 2 2 3 24 26 27 28 20 20 25 25 30 21 21 22 22 23 23 24 24 26 26 27 27 28 28 2 9 29 28 GUARD HOUSE 9039927.43 9264128.47S.MH 9264227.60S.MH 92801 N: 210305.828' E: 2324675.097' EL:27.950' TRV FLY 92802 N: 210301.245' E: 2324835.038' EL:27.658' TRV FLY 92803 N: 209994.221' E: 2324893.750' EL:27.924' TRV FLY 9310227.30BUSH 9310327.05BUSH 9310427.06BUSH 9310527.16BUSH 9312028.82SP 9313529.03LSA 9313628.81LSA 9313728.89LSA 9313828.96LSA 9323429.52LSA 9323529.75LSA 9323629.65LSA 9323729.81LSA 9327529.67STMP X X X X X X X X X X X X X 22" OAK 16" OAK 30" OAK 18" SYCAMORE 18" GUM 36" OAK 26" SYCAMORE 30" SYCAMORE 20" MAGNOLIA 26" MAGNOLIA 20" GUM 32" PINE 24" GUM 24" OAK 8" OAK 26" OAK 28" OAK 32" OAK 10" SYCAMORE 8" SYCAMORE THOM A S E D I S O N A V E N U E CA S T L E H A Y N E R O A D 4 - 4 8 " C M P ' S 29 2 9 2 9 29 29 28 27 2 6 2 7 2 8 29 > > > > >> > > >> > > >> > > 30 30 29 29 28 28 28 29 2 8 2 9 28 28 29 FLOWS TO NPDES PERMITTED OUTFALL 15 (NCS000617) FLOWS TO NPDES PERMITTED OUTFALL 15 (NCS000617) 4 - 4 8 " C M P ' S 28 29 30 31 3 0 2 5 21 2 9 28 TP T P TP LOD LOD LO D LO D LOD L O D L O D L O D L O D L O D L O D LOD LOD LOD LOD LOD LOD LOD LOD LOD L O D L O D L O D L O D SF SF S F S F S F S F S F S F S F SF SF SF SF LOD LOD LOD LOD LOD LOD LOD S F S F SF SF SF SF SF SF SF SF SF SF SF SF S F DRAINAGE AREA DA-6 AREA = 0.153 ACRES DRAINAGE AREA DA-5 AREA = 0.52 ACRES DRAINAGE AREA DA-4 AREA = 0.069 ACRES DRAINAGE AREA DA-1 AREA = 0.232 ACRES DRAINAGE AREA DA-2 AREA = 0.044 ACRES DRAINAGE AREA DA-3 AREA = 0.263 ACRES POA-02 CUMULATION OF DA-2 & DA-3 POA-01 CUMULATION OF DA-1, DA-4, & DA-5 18" RCP (87LF @ 0.50%) 18" RCP (157LF @ 0.50%) POTENTIAL INTERMITTENT STREAM (STREAM H) POTENTIAL PALUSTRINE FORESTED WETLAND (WETLAND A) ISSUE/REVISION DESCRIPTIONYREVDM DR.ENG. SCALE HORIZONTAL: SCALE VERTICAL: SHEET TITLE: PROJECT: DATE: SHEET NO. REVISION NO. PROJECT NO.: APPROVED BY: RS - 04.04.2025 GE AEROSPACE NORTH GATE IMPROVEMENTS WILMINGTON, NORTH CAROLINA 6260230100 DRAWN BY: CP REVIEWED BY: RS SEAL:SEAL: WSP USA INC. 5710 OLEANDER DRIVE, SUITE 110 WILMINGTON, NC 28403 TEL:(910) 452-1185 LICENSURE: NC ENG: F-0165 NC GEOLOGY: C-557 ENGINEER:CLIENT: 3905 CASTLE HAYNE RD. CASTLE HAYNE, NC 28429 FOR REVIEW ONLY - NOT FOR CONSTRUCTION FOR REVIEW ONLY - NOT FOR CONSTRUCTION EX. 2 N/A 1"=20' 0 SCALE: 1"=20' (Horiz.) 40'20'20' LEGEND PROPERTY LINE EXISTING STORM PIPE NOTES: ·RUNOFF FROM PROPOSED SITE FLOWS TO NPDES PERMITTED OUTFALL 15 (NCS000617) PROPOSED MAJOR CONTOUR PROPOSED MINOR CONTOUR PROPOSED STORM PIPE EXISTING MAJOR CONTOUR EXISTING MINOR CONTOUR 20 19 20 19 DRAINAGE FLOW ARROW DRAINAGE AREA - SILT FENCE DRAINAGE AREA - INLETS DRAINAGE AREA MAP - EXHIBIT 2 APPENDIX E CALCULATIONS 4/2/2025 DESCRIPTION: ENGINEER:CP RS PROJECT NO. RS Channel Flow Total Min Final Location "n" L(ft) P2 S(%) T(min) S(%) u:p V(f/s) L(ft) T(min) Q25 Bw(ft) Slope1, H:1ftV Slope2, H:1ftV Channel Slope (ft/ft) "n" Depth (ft)V(f/s) L(ft) T(min) Tc(min) Tc Tc(min) DA-1 0.013 100 2.56 0.5 2.70 0.5 P 1.44 60 0.70 5.1 0.0 5.0 5.0 0.003 0.050 1.00 1.02 240 3.93 7.32 5 7 DA-2 0.013 25 2.56 2 0.51 0.55 U 1.20 235 3.27 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A 3.78 5 5 ENGINEER: PREPARED FOR : TIME OF CONCENTRATION WSP USA Inc. Time of Concentration (Post Development) GE AEROSPACE NORTH GATE IMPROVEMENTS GE AVIATION WILMINGTON, LLC ORIGINATOR: CHECKER: DATE PREPARED: Sheet Flow Shallow Conc. Flow PROJECT: US-EI-6260230100 4/2/2025 DESCRIPTION: GE AVIATION WILMINGTON, LLC ENGINEER: CP RS PROJECT NO. RS PRE Development % Coverage by Hydrologic Soil Group Soil Type A B C D Onslow Loamy Fine Sand 80.0 0.0 0.0 0.0 Urban Land 0.0 0.0 0.0 20.0 100 Total = 80.0% 0.0% 0.0% 20.0%100% SCS CN by Hydrologic Soil Group Weighted % Land Use A B C D CN Coverage Woods (Good) 30 55 70 77 39.4 0% Grassed Open Space (Fair)49 69 79 84 56.0 45% Impervious 98 98 98 98 98.0 55% 100.0% Composite CN = 79 NOTES: 1. SCS Runoff Curve Numbers taken from NRCS TR-55 Table 2-2a. 2. Soil data taken from NRCS Web Soil Survey. SCS CURVE NUMBER CALCULATION PROJECT:GE AEROSPACE NORTH GATE IMPROVEMENTS Pre-Development SCS CN WSP USA Inc. US-EI-6260230100 DATE PREPARED: PREPARED FOR : ORIGINATOR: CHECKER: ENGINEER: 4/2/2025 DESCRIPTION: GE AVIATION WILMINGTON, LLC ENGINEER: CP RS PROJECT NO. RS POST Development % Coverage by Hydrologic Soil Group Soil Type A B C D Onslow Loamy Fine Sand 80.0 0.0 0.0 0.0 Urban Land 0.0 0.0 0.0 20.0 100 Total = 80.0% 0.0% 0.0% 20.0%100% SCS CN by Hydrologic Soil Group Weighted % Land Use A B C D CN Coverage Woods (Good) 30 55 70 77 39.4 0% Grassed Open Space (Fair) 39 61 74 80 47.2 29% Impervious 98 98 98 98 98.0 71% 100.0% Composite CN = 83 NOTES: 1. SCS Runoff Curve Numbers taken from NRCS TR-55 Table 2-2a. 2. Soil data taken from NRCS Web Soil Survey. SCS CURVE NUMBER CALCULATION PROJECT:GE AEROSPACE NORTH GATE IMPROVEMENTS DATE PREPARED: Post-Development SCS CN PREPARED FOR : WSP USA Inc.ORIGINATOR: CHECKER: US-EI-6260230100 ENGINEER: Hydraflow Table of Contents GE Aerospace North Gate - Pre Post.gpw Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Watershed Model Schematic...................................................................................... 1 Hydrograph Return Period Recap............................................................................. 2 2 - Year Summary Report......................................................................................................................... 3 Hydrograph Reports................................................................................................................... 4 Hydrograph No. 1, SCS Runoff, PRE-DEVELOPMENT DA-1................................................. 4 Hydrograph No. 2, SCS Runoff, POST-DEVELOPMENT DA-1............................................... 5 Hydrograph No. 3, SCS Runoff, PRE-DEVELOPMENT DA-2................................................. 6 Hydrograph No. 4, SCS Runoff, POST-DEVELOPEMENT DA-2............................................ 7 Hydrograph No. 5, Reach, SWALE.......................................................................................... 8 Hydrograph No. 6, Combine, COMBINED PRE-DEVELOPMENT.......................................... 9 Hydrograph No. 7, Combine, COMBINED POST-DEVELOPMENT...................................... 10 10 - Year Summary Report....................................................................................................................... 11 Hydrograph Reports................................................................................................................. 12 Hydrograph No. 1, SCS Runoff, PRE-DEVELOPMENT DA-1............................................... 12 Hydrograph No. 2, SCS Runoff, POST-DEVELOPMENT DA-1............................................. 13 Hydrograph No. 3, SCS Runoff, PRE-DEVELOPMENT DA-2............................................... 14 Hydrograph No. 4, SCS Runoff, POST-DEVELOPEMENT DA-2.......................................... 15 Hydrograph No. 5, Reach, SWALE........................................................................................ 16 Hydrograph No. 6, Combine, COMBINED PRE-DEVELOPMENT........................................ 17 Hydrograph No. 7, Combine, COMBINED POST-DEVELOPMENT...................................... 18 25 - Year Summary Report....................................................................................................................... 19 Hydrograph Reports................................................................................................................. 20 Hydrograph No. 1, SCS Runoff, PRE-DEVELOPMENT DA-1............................................... 20 Hydrograph No. 2, SCS Runoff, POST-DEVELOPMENT DA-1............................................. 21 Hydrograph No. 3, SCS Runoff, PRE-DEVELOPMENT DA-2............................................... 22 Hydrograph No. 4, SCS Runoff, POST-DEVELOPEMENT DA-2.......................................... 23 Hydrograph No. 5, Reach, SWALE........................................................................................ 24 Hydrograph No. 6, Combine, COMBINED PRE-DEVELOPMENT........................................ 25 Hydrograph No. 7, Combine, COMBINED POST-DEVELOPMENT...................................... 26 50 - Year Summary Report....................................................................................................................... 27 Hydrograph Reports................................................................................................................. 28 Hydrograph No. 1, SCS Runoff, PRE-DEVELOPMENT DA-1............................................... 28 Hydrograph No. 2, SCS Runoff, POST-DEVELOPMENT DA-1............................................. 29 Hydrograph No. 3, SCS Runoff, PRE-DEVELOPMENT DA-2............................................... 30 Hydrograph No. 4, SCS Runoff, POST-DEVELOPEMENT DA-2.......................................... 31 Hydrograph No. 5, Reach, SWALE........................................................................................ 32 Hydrograph No. 6, Combine, COMBINED PRE-DEVELOPMENT........................................ 33 Hydrograph No. 7, Combine, COMBINED POST-DEVELOPMENT...................................... 34 100 - Year Contents continued...GE Aerospace North Gate - Pre Post.gpw Summary Report....................................................................................................................... 35 Hydrograph Reports................................................................................................................. 36 Hydrograph No. 1, SCS Runoff, PRE-DEVELOPMENT DA-1............................................... 36 Hydrograph No. 2, SCS Runoff, POST-DEVELOPMENT DA-1............................................. 37 Hydrograph No. 3, SCS Runoff, PRE-DEVELOPMENT DA-2............................................... 38 Hydrograph No. 4, SCS Runoff, POST-DEVELOPEMENT DA-2.......................................... 39 Hydrograph No. 5, Reach, SWALE........................................................................................ 40 Hydrograph No. 6, Combine, COMBINED PRE-DEVELOPMENT........................................ 41 Hydrograph No. 7, Combine, COMBINED POST-DEVELOPMENT...................................... 42 1 23 4 5 6 7 1 Watershed Model Schematic Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Project: GE Aerospace North Gate - Pre Post.gpw Wednesday, 04 / 2 / 2025 Hyd.Origin Description Legend 1 SCS Runoff PRE-DEVELOPMENT DA-1 2 SCS Runoff POST-DEVELOPMENT DA-1 3 SCS Runoff PRE-DEVELOPMENT DA-2 4 SCS Runoff POST-DEVELOPEMENT DA-2 5 Reach SWALE 6 Combine COMBINED PRE-DEVELOPMENT 7 Combine COMBINED POST-DEVELOPMENT Hydrograph Return Period Recap 2 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 ------ 1.063 1.467 ------- 2.155 2.772 3.731 4.564 5.550 PRE-DEVELOPMENT DA-1 2 SCS Runoff ------ 1.169 1.563 ------- 2.223 2.807 3.709 4.489 5.410 POST-DEVELOPMENT DA-1 3 SCS Runoff ------ 0.628 0.866 ------- 1.272 1.636 2.203 2.695 3.276 PRE-DEVELOPMENT DA-2 4 SCS Runoff ------ 0.739 0.986 ------- 1.400 1.766 2.331 2.820 3.396 POST-DEVELOPEMENT DA-2 5 Reach 2 1.074 1.450 ------- 2.082 2.643 3.509 4.258 5.142 SWALE 6 Combine 1, 3, 1.691 2.333 ------- 3.427 4.408 5.933 7.259 8.826 COMBINED PRE-DEVELOPMENT 7 Combine 4, 5, 1.572 2.130 ------- 3.072 3.913 5.218 6.353 7.698 COMBINED POST-DEVELOPMENT Proj. file: GE Aerospace North Gate - Pre Post.gpw Wednesday, 04 / 2 / 2025 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Hydrograph Summary Report 3 Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph No. type flow interval Peak volume hyd(s) elevation strge used Description (origin) (cfs) (min) (min) (cuft) (ft) (cuft) 1 SCS Runoff 1.467 2 724 4,384 ------ ------ ------ PRE-DEVELOPMENT DA-1 2 SCS Runoff 1.563 2 726 5,347 ------ ------ ------ POST-DEVELOPMENT DA-1 3 SCS Runoff 0.866 2 724 2,588 ------ ------ ------ PRE-DEVELOPMENT DA-2 4 SCS Runoff 0.986 2 724 2,959 ------ ------ ------ POST-DEVELOPEMENT DA-2 5 Reach 1.450 2 730 5,344 2 ------ ------ SWALE 6 Combine 2.333 2 724 6,973 1, 3, ------ ------ COMBINED PRE-DEVELOPMENT 7 Combine 2.130 2 726 8,303 4, 5, ------ ------ COMBINED POST-DEVELOPMENT GE Aerospace North Gate - Pre Post.gpw Return Period: 2 Year Wednesday, 04 / 2 / 2025 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 1 PRE-DEVELOPMENT DA-1 Hydrograph type = SCS Runoff Peak discharge = 1.467 cfs Storm frequency = 2 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 4,384 cuft Drainage area = 0.520 ac Curve number = 79 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 4.62 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 4 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 Q (cfs) Time (min) PRE-DEVELOPMENT DA-1 Hyd. No. 1 -- 2 Year Hyd No. 1 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 2 POST-DEVELOPMENT DA-1 Hydrograph type = SCS Runoff Peak discharge = 1.563 cfs Storm frequency = 2 yrs Time to peak = 726 min Time interval = 2 min Hyd. volume = 5,347 cuft Drainage area = 0.520 ac Curve number = 83 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 7.00 min Total precip. = 4.62 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 5 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 Q (cfs) Time (min) POST-DEVELOPMENT DA-1 Hyd. No. 2 -- 2 Year Hyd No. 2 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 3 PRE-DEVELOPMENT DA-2 Hydrograph type = SCS Runoff Peak discharge = 0.866 cfs Storm frequency = 2 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 2,588 cuft Drainage area = 0.307 ac Curve number = 79 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 4.62 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 6 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 0.10 0.10 0.20 0.20 0.30 0.30 0.40 0.40 0.50 0.50 0.60 0.60 0.70 0.70 0.80 0.80 0.90 0.90 1.00 1.00 Q (cfs) Time (min) PRE-DEVELOPMENT DA-2 Hyd. No. 3 -- 2 Year Hyd No. 3 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 4 POST-DEVELOPEMENT DA-2 Hydrograph type = SCS Runoff Peak discharge = 0.986 cfs Storm frequency = 2 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 2,959 cuft Drainage area = 0.307 ac Curve number = 83 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 4.62 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 7 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 0.10 0.10 0.20 0.20 0.30 0.30 0.40 0.40 0.50 0.50 0.60 0.60 0.70 0.70 0.80 0.80 0.90 0.90 1.00 1.00 Q (cfs) Time (min) POST-DEVELOPEMENT DA-2 Hyd. No. 4 -- 2 Year Hyd No. 4 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 5 SWALE Hydrograph type = Reach Peak discharge = 1.450 cfs Storm frequency = 2 yrs Time to peak = 730 min Time interval = 2 min Hyd. volume = 5,344 cuft Inflow hyd. No. = 2 - POST-DEVELOPMENT DA-1Section type = Triangular Reach length = 190.0 ft Channel slope = 0.3 % Manning's n = 0.050 Bottom width = 0.0 ft Side slope = 5.0:1 Max. depth = 0.0 ft Rating curve x = 0.603 Rating curve m = 1.333 Ave. velocity = 0.76 ft/s Routing coeff. = 0.4871 Modified Att-Kin routing method used. 8 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 Q (cfs) Time (min) SWALE Hyd. No. 5 -- 2 Year Hyd No. 5 Hyd No. 2 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 6 COMBINED PRE-DEVELOPMENT Hydrograph type = Combine Peak discharge = 2.333 cfs Storm frequency = 2 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 6,973 cuft Inflow hyds. = 1, 3 Contrib. drain. area = 0.827 ac 9 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 Q (cfs) Time (min) COMBINED PRE-DEVELOPMENT Hyd. No. 6 -- 2 Year Hyd No. 6 Hyd No. 1 Hyd No. 3 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 7 COMBINED POST-DEVELOPMENT Hydrograph type = Combine Peak discharge = 2.130 cfs Storm frequency = 2 yrs Time to peak = 726 min Time interval = 2 min Hyd. volume = 8,303 cuft Inflow hyds. = 4, 5 Contrib. drain. area = 0.307 ac 10 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 Q (cfs) Time (min) COMBINED POST-DEVELOPMENT Hyd. No. 7 -- 2 Year Hyd No. 7 Hyd No. 4 Hyd No. 5 Hydrograph Summary Report 11 Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph No. type flow interval Peak volume hyd(s) elevation strge used Description (origin) (cfs) (min) (min) (cuft) (ft) (cuft) 1 SCS Runoff 2.772 2 724 8,372 ------ ------ ------ PRE-DEVELOPMENT DA-1 2 SCS Runoff 2.807 2 726 9,776 ------ ------ ------ POST-DEVELOPMENT DA-1 3 SCS Runoff 1.636 2 724 4,943 ------ ------ ------ PRE-DEVELOPMENT DA-2 4 SCS Runoff 1.766 2 724 5,411 ------ ------ ------ POST-DEVELOPEMENT DA-2 5 Reach 2.643 2 730 9,774 2 ------ ------ SWALE 6 Combine 4.408 2 724 13,315 1, 3, ------ ------ COMBINED PRE-DEVELOPMENT 7 Combine 3.913 2 726 15,184 4, 5, ------ ------ COMBINED POST-DEVELOPMENT GE Aerospace North Gate - Pre Post.gpw Return Period: 10 Year Wednesday, 04 / 2 / 2025 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 1 PRE-DEVELOPMENT DA-1 Hydrograph type = SCS Runoff Peak discharge = 2.772 cfs Storm frequency = 10 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 8,372 cuft Drainage area = 0.520 ac Curve number = 79 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 7.16 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 12 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 Q (cfs) Time (min) PRE-DEVELOPMENT DA-1 Hyd. No. 1 -- 10 Year Hyd No. 1 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 2 POST-DEVELOPMENT DA-1 Hydrograph type = SCS Runoff Peak discharge = 2.807 cfs Storm frequency = 10 yrs Time to peak = 726 min Time interval = 2 min Hyd. volume = 9,776 cuft Drainage area = 0.520 ac Curve number = 83 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 7.00 min Total precip. = 7.16 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 13 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 Q (cfs) Time (min) POST-DEVELOPMENT DA-1 Hyd. No. 2 -- 10 Year Hyd No. 2 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 3 PRE-DEVELOPMENT DA-2 Hydrograph type = SCS Runoff Peak discharge = 1.636 cfs Storm frequency = 10 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 4,943 cuft Drainage area = 0.307 ac Curve number = 79 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 7.16 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 14 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 Q (cfs) Time (min) PRE-DEVELOPMENT DA-2 Hyd. No. 3 -- 10 Year Hyd No. 3 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 4 POST-DEVELOPEMENT DA-2 Hydrograph type = SCS Runoff Peak discharge = 1.766 cfs Storm frequency = 10 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 5,411 cuft Drainage area = 0.307 ac Curve number = 83 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 7.16 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 15 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 Q (cfs) Time (min) POST-DEVELOPEMENT DA-2 Hyd. No. 4 -- 10 Year Hyd No. 4 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 5 SWALE Hydrograph type = Reach Peak discharge = 2.643 cfs Storm frequency = 10 yrs Time to peak = 730 min Time interval = 2 min Hyd. volume = 9,774 cuft Inflow hyd. No. = 2 - POST-DEVELOPMENT DA-1Section type = Triangular Reach length = 190.0 ft Channel slope = 0.3 % Manning's n = 0.050 Bottom width = 0.0 ft Side slope = 5.0:1 Max. depth = 0.0 ft Rating curve x = 0.603 Rating curve m = 1.333 Ave. velocity = 0.89 ft/s Routing coeff. = 0.5430 Modified Att-Kin routing method used. 16 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 Q (cfs) Time (min) SWALE Hyd. No. 5 -- 10 Year Hyd No. 5 Hyd No. 2 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 6 COMBINED PRE-DEVELOPMENT Hydrograph type = Combine Peak discharge = 4.408 cfs Storm frequency = 10 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 13,315 cuft Inflow hyds. = 1, 3 Contrib. drain. area = 0.827 ac 17 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 5.00 5.00 Q (cfs) Time (min) COMBINED PRE-DEVELOPMENT Hyd. No. 6 -- 10 Year Hyd No. 6 Hyd No. 1 Hyd No. 3 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 7 COMBINED POST-DEVELOPMENT Hydrograph type = Combine Peak discharge = 3.913 cfs Storm frequency = 10 yrs Time to peak = 726 min Time interval = 2 min Hyd. volume = 15,184 cuft Inflow hyds. = 4, 5 Contrib. drain. area = 0.307 ac 18 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 Q (cfs) Time (min) COMBINED POST-DEVELOPMENT Hyd. No. 7 -- 10 Year Hyd No. 7 Hyd No. 4 Hyd No. 5 Hydrograph Summary Report 19 Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph No. type flow interval Peak volume hyd(s) elevation strge used Description (origin) (cfs) (min) (min) (cuft) (ft) (cuft) 1 SCS Runoff 3.731 2 724 11,406 ------ ------ ------ PRE-DEVELOPMENT DA-1 2 SCS Runoff 3.709 2 726 13,093 ------ ------ ------ POST-DEVELOPMENT DA-1 3 SCS Runoff 2.203 2 724 6,734 ------ ------ ------ PRE-DEVELOPMENT DA-2 4 SCS Runoff 2.331 2 724 7,247 ------ ------ ------ POST-DEVELOPEMENT DA-2 5 Reach 3.509 2 730 13,092 2 ------ ------ SWALE 6 Combine 5.933 2 724 18,139 1, 3, ------ ------ COMBINED PRE-DEVELOPMENT 7 Combine 5.218 2 726 20,339 4, 5, ------ ------ COMBINED POST-DEVELOPMENT GE Aerospace North Gate - Pre Post.gpw Return Period: 25 Year Wednesday, 04 / 2 / 2025 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 1 PRE-DEVELOPMENT DA-1 Hydrograph type = SCS Runoff Peak discharge = 3.731 cfs Storm frequency = 25 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 11,406 cuft Drainage area = 0.520 ac Curve number = 79 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 9.00 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 20 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 Q (cfs) Time (min) PRE-DEVELOPMENT DA-1 Hyd. No. 1 -- 25 Year Hyd No. 1 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 2 POST-DEVELOPMENT DA-1 Hydrograph type = SCS Runoff Peak discharge = 3.709 cfs Storm frequency = 25 yrs Time to peak = 726 min Time interval = 2 min Hyd. volume = 13,093 cuft Drainage area = 0.520 ac Curve number = 83 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 7.00 min Total precip. = 9.00 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 21 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 Q (cfs) Time (min) POST-DEVELOPMENT DA-1 Hyd. No. 2 -- 25 Year Hyd No. 2 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 3 PRE-DEVELOPMENT DA-2 Hydrograph type = SCS Runoff Peak discharge = 2.203 cfs Storm frequency = 25 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 6,734 cuft Drainage area = 0.307 ac Curve number = 79 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 9.00 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 22 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 Q (cfs) Time (min) PRE-DEVELOPMENT DA-2 Hyd. No. 3 -- 25 Year Hyd No. 3 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 4 POST-DEVELOPEMENT DA-2 Hydrograph type = SCS Runoff Peak discharge = 2.331 cfs Storm frequency = 25 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 7,247 cuft Drainage area = 0.307 ac Curve number = 83 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 9.00 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 23 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 Q (cfs) Time (min) POST-DEVELOPEMENT DA-2 Hyd. No. 4 -- 25 Year Hyd No. 4 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 5 SWALE Hydrograph type = Reach Peak discharge = 3.509 cfs Storm frequency = 25 yrs Time to peak = 730 min Time interval = 2 min Hyd. volume = 13,092 cuft Inflow hyd. No. = 2 - POST-DEVELOPMENT DA-1Section type = Triangular Reach length = 190.0 ft Channel slope = 0.3 % Manning's n = 0.050 Bottom width = 0.0 ft Side slope = 5.0:1 Max. depth = 0.0 ft Rating curve x = 0.603 Rating curve m = 1.333 Ave. velocity = 0.95 ft/s Routing coeff. = 0.5710 Modified Att-Kin routing method used. 24 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 Q (cfs) Time (min) SWALE Hyd. No. 5 -- 25 Year Hyd No. 5 Hyd No. 2 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 6 COMBINED PRE-DEVELOPMENT Hydrograph type = Combine Peak discharge = 5.933 cfs Storm frequency = 25 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 18,139 cuft Inflow hyds. = 1, 3 Contrib. drain. area = 0.827 ac 25 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 5.00 5.00 6.00 6.00 Q (cfs) Time (min) COMBINED PRE-DEVELOPMENT Hyd. No. 6 -- 25 Year Hyd No. 6 Hyd No. 1 Hyd No. 3 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 7 COMBINED POST-DEVELOPMENT Hydrograph type = Combine Peak discharge = 5.218 cfs Storm frequency = 25 yrs Time to peak = 726 min Time interval = 2 min Hyd. volume = 20,339 cuft Inflow hyds. = 4, 5 Contrib. drain. area = 0.307 ac 26 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 5.00 5.00 6.00 6.00 Q (cfs) Time (min) COMBINED POST-DEVELOPMENT Hyd. No. 7 -- 25 Year Hyd No. 7 Hyd No. 4 Hyd No. 5 Hydrograph Summary Report 27 Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph No. type flow interval Peak volume hyd(s) elevation strge used Description (origin) (cfs) (min) (min) (cuft) (ft) (cuft) 1 SCS Runoff 4.564 2 724 14,096 ------ ------ ------ PRE-DEVELOPMENT DA-1 2 SCS Runoff 4.489 2 726 16,016 ------ ------ ------ POST-DEVELOPMENT DA-1 3 SCS Runoff 2.695 2 724 8,322 ------ ------ ------ PRE-DEVELOPMENT DA-2 4 SCS Runoff 2.820 2 724 8,865 ------ ------ ------ POST-DEVELOPEMENT DA-2 5 Reach 4.258 2 730 16,015 2 ------ ------ SWALE 6 Combine 7.259 2 724 22,418 1, 3, ------ ------ COMBINED PRE-DEVELOPMENT 7 Combine 6.353 2 726 24,880 4, 5, ------ ------ COMBINED POST-DEVELOPMENT GE Aerospace North Gate - Pre Post.gpw Return Period: 50 Year Wednesday, 04 / 2 / 2025 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 1 PRE-DEVELOPMENT DA-1 Hydrograph type = SCS Runoff Peak discharge = 4.564 cfs Storm frequency = 50 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 14,096 cuft Drainage area = 0.520 ac Curve number = 79 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 10.60 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 28 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 5.00 5.00 Q (cfs) Time (min) PRE-DEVELOPMENT DA-1 Hyd. No. 1 -- 50 Year Hyd No. 1 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 2 POST-DEVELOPMENT DA-1 Hydrograph type = SCS Runoff Peak discharge = 4.489 cfs Storm frequency = 50 yrs Time to peak = 726 min Time interval = 2 min Hyd. volume = 16,016 cuft Drainage area = 0.520 ac Curve number = 83 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 7.00 min Total precip. = 10.60 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 29 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 5.00 5.00 Q (cfs) Time (min) POST-DEVELOPMENT DA-1 Hyd. No. 2 -- 50 Year Hyd No. 2 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 3 PRE-DEVELOPMENT DA-2 Hydrograph type = SCS Runoff Peak discharge = 2.695 cfs Storm frequency = 50 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 8,322 cuft Drainage area = 0.307 ac Curve number = 79 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 10.60 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 30 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 Q (cfs) Time (min) PRE-DEVELOPMENT DA-2 Hyd. No. 3 -- 50 Year Hyd No. 3 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 4 POST-DEVELOPEMENT DA-2 Hydrograph type = SCS Runoff Peak discharge = 2.820 cfs Storm frequency = 50 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 8,865 cuft Drainage area = 0.307 ac Curve number = 83 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 10.60 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 31 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 Q (cfs) Time (min) POST-DEVELOPEMENT DA-2 Hyd. No. 4 -- 50 Year Hyd No. 4 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 5 SWALE Hydrograph type = Reach Peak discharge = 4.258 cfs Storm frequency = 50 yrs Time to peak = 730 min Time interval = 2 min Hyd. volume = 16,015 cuft Inflow hyd. No. = 2 - POST-DEVELOPMENT DA-1Section type = Triangular Reach length = 190.0 ft Channel slope = 0.3 % Manning's n = 0.050 Bottom width = 0.0 ft Side slope = 5.0:1 Max. depth = 0.0 ft Rating curve x = 0.603 Rating curve m = 1.333 Ave. velocity = 1.00 ft/s Routing coeff. = 0.5907 Modified Att-Kin routing method used. 32 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 5.00 5.00 Q (cfs) Time (min) SWALE Hyd. No. 5 -- 50 Year Hyd No. 5 Hyd No. 2 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 6 COMBINED PRE-DEVELOPMENT Hydrograph type = Combine Peak discharge = 7.259 cfs Storm frequency = 50 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 22,418 cuft Inflow hyds. = 1, 3 Contrib. drain. area = 0.827 ac 33 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 2.00 2.00 4.00 4.00 6.00 6.00 8.00 8.00 Q (cfs) Time (min) COMBINED PRE-DEVELOPMENT Hyd. No. 6 -- 50 Year Hyd No. 6 Hyd No. 1 Hyd No. 3 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 7 COMBINED POST-DEVELOPMENT Hydrograph type = Combine Peak discharge = 6.353 cfs Storm frequency = 50 yrs Time to peak = 726 min Time interval = 2 min Hyd. volume = 24,880 cuft Inflow hyds. = 4, 5 Contrib. drain. area = 0.307 ac 34 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 5.00 5.00 6.00 6.00 7.00 7.00 Q (cfs) Time (min) COMBINED POST-DEVELOPMENT Hyd. No. 7 -- 50 Year Hyd No. 7 Hyd No. 4 Hyd No. 5 Hydrograph Summary Report 35 Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph No. type flow interval Peak volume hyd(s) elevation strge used Description (origin) (cfs) (min) (min) (cuft) (ft) (cuft) 1 SCS Runoff 5.550 2 724 17,330 ------ ------ ------ PRE-DEVELOPMENT DA-1 2 SCS Runoff 5.410 2 726 19,516 ------ ------ ------ POST-DEVELOPMENT DA-1 3 SCS Runoff 3.276 2 724 10,232 ------ ------ ------ PRE-DEVELOPMENT DA-2 4 SCS Runoff 3.396 2 724 10,802 ------ ------ ------ POST-DEVELOPEMENT DA-2 5 Reach 5.142 2 730 19,514 2 ------ ------ SWALE 6 Combine 8.826 2 724 27,562 1, 3, ------ ------ COMBINED PRE-DEVELOPMENT 7 Combine 7.698 2 726 30,316 4, 5, ------ ------ COMBINED POST-DEVELOPMENT GE Aerospace North Gate - Pre Post.gpw Return Period: 100 Year Wednesday, 04 / 2 / 2025 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 1 PRE-DEVELOPMENT DA-1 Hydrograph type = SCS Runoff Peak discharge = 5.550 cfs Storm frequency = 100 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 17,330 cuft Drainage area = 0.520 ac Curve number = 79 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 12.50 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 36 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 5.00 5.00 6.00 6.00 Q (cfs) Time (min) PRE-DEVELOPMENT DA-1 Hyd. No. 1 -- 100 Year Hyd No. 1 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 2 POST-DEVELOPMENT DA-1 Hydrograph type = SCS Runoff Peak discharge = 5.410 cfs Storm frequency = 100 yrs Time to peak = 726 min Time interval = 2 min Hyd. volume = 19,516 cuft Drainage area = 0.520 ac Curve number = 83 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 7.00 min Total precip. = 12.50 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 37 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 5.00 5.00 6.00 6.00 Q (cfs) Time (min) POST-DEVELOPMENT DA-1 Hyd. No. 2 -- 100 Year Hyd No. 2 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 3 PRE-DEVELOPMENT DA-2 Hydrograph type = SCS Runoff Peak discharge = 3.276 cfs Storm frequency = 100 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 10,232 cuft Drainage area = 0.307 ac Curve number = 79 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 12.50 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 38 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 Q (cfs) Time (min) PRE-DEVELOPMENT DA-2 Hyd. No. 3 -- 100 Year Hyd No. 3 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 4 POST-DEVELOPEMENT DA-2 Hydrograph type = SCS Runoff Peak discharge = 3.396 cfs Storm frequency = 100 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 10,802 cuft Drainage area = 0.307 ac Curve number = 83 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 5.00 min Total precip. = 12.50 in Distribution = Type III Storm duration = 24 hrs Shape factor = 484 39 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 Q (cfs) Time (min) POST-DEVELOPEMENT DA-2 Hyd. No. 4 -- 100 Year Hyd No. 4 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 5 SWALE Hydrograph type = Reach Peak discharge = 5.142 cfs Storm frequency = 100 yrs Time to peak = 730 min Time interval = 2 min Hyd. volume = 19,514 cuft Inflow hyd. No. = 2 - POST-DEVELOPMENT DA-1Section type = Triangular Reach length = 190.0 ft Channel slope = 0.3 % Manning's n = 0.050 Bottom width = 0.0 ft Side slope = 5.0:1 Max. depth = 0.0 ft Rating curve x = 0.603 Rating curve m = 1.333 Ave. velocity = 1.04 ft/s Routing coeff. = 0.6103 Modified Att-Kin routing method used. 40 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 1.00 1.00 2.00 2.00 3.00 3.00 4.00 4.00 5.00 5.00 6.00 6.00 Q (cfs) Time (min) SWALE Hyd. No. 5 -- 100 Year Hyd No. 5 Hyd No. 2 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 6 COMBINED PRE-DEVELOPMENT Hydrograph type = Combine Peak discharge = 8.826 cfs Storm frequency = 100 yrs Time to peak = 724 min Time interval = 2 min Hyd. volume = 27,562 cuft Inflow hyds. = 1, 3 Contrib. drain. area = 0.827 ac 41 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 Q (cfs) 0.00 0.00 2.00 2.00 4.00 4.00 6.00 6.00 8.00 8.00 10.00 10.00 Q (cfs) Time (min) COMBINED PRE-DEVELOPMENT Hyd. No. 6 -- 100 Year Hyd No. 6 Hyd No. 1 Hyd No. 3 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2020.4 Wednesday, 04 / 2 / 2025 Hyd. No. 7 COMBINED POST-DEVELOPMENT Hydrograph type = Combine Peak discharge = 7.698 cfs Storm frequency = 100 yrs Time to peak = 726 min Time interval = 2 min Hyd. volume = 30,316 cuft Inflow hyds. = 4, 5 Contrib. drain. area = 0.307 ac 42 0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 Q (cfs) 0.00 0.00 2.00 2.00 4.00 4.00 6.00 6.00 8.00 8.00 Q (cfs) Time (min) COMBINED POST-DEVELOPMENT Hyd. No. 7 -- 100 Year Hyd No. 7 Hyd No. 4 Hyd No. 5 4/2/2025 DESCRIPTION: GE AVIATION WILMINGTON, LLC ENGINEER: CP RS PROJECT NO. RS IMPERVIOUS (acre) GRASSED AREA (acre)IMPERVIOUS GRASSED AREA DA-1 0.23 0.17 0.06 0.95 0.15 DA-2 0.04 0.03 0.02 0.95 0.15 DA-3 0.26 0.17 0.09 0.95 0.15 DA-4 0.07 0.06 0.01 0.95 0.15 DA-5 0.52 0.43 0.09 0.95 0.15 0.86 0.82 COMPOSITE C FACTOR 0.75 0.62 0.67 US-EI-6260230100 ENGINEER: POST DEVELOPMENT DA TOTAL AREA (acre) BUA BREAKDOWN C FACTORS COMPOSITE C FACTOR CALCULATION PROJECT:GE AEROSPACE NORTH GATE IMPROVEMENTS DATE PREPARED: COMPOSITE C FACTOR CALCULATION PREPARED FOR : WSP USA Inc.ORIGINATOR: CHECKER: 4/2/2025 DESCRIPTION: GE AVIATION WILMINGTON, LLC ENGINEER: CP RAS PROJECT NO. RAS Swale 1 Area (ac) = 0.52 C factor = 0.82 I25 (in/hr) =10.90 I50 (in/hr) =10.90 I100 (in/hr) =11.80 CF25 =1.1 CF50 =1.2 CF100 =1.25 Tc = 5 (min) formulas (Q) Design Q25 =5.11 (cfs) NOAA Database (Q50) Design Q50=5.58 (cfs) (Q100) Design Q100=6.29 (cfs) (b) Base width = 0 (ft) Q = CIA or AV (z) sideslopes = 5 (z:1) A = bd + (zd)2 (d) depth = 1.25 (ft) P = b + 2d x ((z)^2+1)^.5 (S) Swale Slope = 0.30% (percent) V = (1.49/n)*R^(2/3)*S^(1/2) (L) Swale Length = 230 (ft) HRT = L/(60*V) (d) (A) (P) (R) (n) (V) (Q) Depth Area Wet'd Per. Hyd Rad. Mannings Velocity Flow (ft) (st) (ft) (ft) (factor) (fps) (cfs) Capacity of Swale 1.25 7.81 12.75 0.613 0.050 1.18 9.20 25-yr Flow Conditions 1.00 5.03 10.23 0.492 0.050 1.02 5.11 50-yr Flow Conditions 1.04 5.37 10.57 0.508 0.050 1.04 5.58 100-yr Flow Conditions 1.08 5.87 11.05 0.531 0.050 1.07 6.29 Swale Calculations PROJECT: DATE PREPARED: PREPARED FOR : GE AEROSPACE NORTH GATE IMPROVEMENTS SWALE CALCULATION WSP USA Inc. US-EI-6260230100 Frequency Factor ORIGINATOR: CHECKER: ENGINEER: PROJECT:GE AEROSPACE NORTH GATE IMPROVEMENTS DATE PREPARED:4/3/2025 DESCRIPTION:CATCHMENT TABLE PREPARED BY :WSP USA, INC PROJECT NO.US-EI-6260230100 Label Outflow Element Area (Unified) (acres) Runoff Coefficient (Rational) Time of Concentration (hours) Notes / Comments DA-4 PROP. DI 0.069 0.86 0.083 DA-5 OPEN END PIPE 0.52 0.82 0.117 CATCHMENT TABLE PROJECT:GE AEROSPACE NORTH GATE IMPROVEMENTS 4/3/2025 DESCRIPTION:INLET SPREAD WSP USA, INC PROJECT NO.US-EI-6260230100 Label Spread / Top Width (ft)Inlet Location Longitudinal Slope (Inlet) (ft/ft) Intercepted Rational Flow (cfs) Bypassed Rational Flow (cfs) Bypass Target Inlet Drainage Area (acres)Inlet C Total Inlet Tc (hours) Total Inlet Intensity (in/h) PROP. DI 2.3 In Sag --0.24 0 --0.069 0.86 0.083 4 CATCH BASIN TABLE (4IN/HR SPREAD) - PROPOSED CONDITION DATE PREPARED: PREPARED BY : PROJECT:GE AEROSPACE NORTH GATE IMPROVEMENTS 4/3/2025 DESCRIPTION:PIPE TABLE WSP USA, INC PROJECT NO.US-EI-6260230100 Start Node Stop Node Upstream Inlet Area (acres) System Drainage Area (ft²) Upstream Inlet Tc (hours) Upstream Inlet C Flow (cfs) Slope (Calculated) (ft/ft) Diameter (in) Manning's n Velocity (ft/s) Length (Unified) (ft) Capacity (Full Flow) (cfs) Time (Pipe Flow) (hours) Invert (Start) (ft) Elevation Ground (Start) (ft) Hydraulic Grade Line (In) (ft) Invert (Stop) (ft) Elevation Ground (Stop) (ft) Hydraulic Grade Line (Out) (ft) OPEN END PIPE PROP. DI 0.52 22,659.00 0.117 0.82 4.74 0.005 18 0.013 4.45 158.6 7.41 0.01 27.09 29.25 27.96 26.30 29.16 27.54 PROP. DI PO-01 0.069 25,670.70 0.08 0.86 7.12 0.005 18 0.013 4.81 87.2 7.46 0.005 26.3 29.16 27.47 25.86 28.00 26.89 NOTES: PIPE TABLE (25-YEAR) - PROPOSED CONDITION DATE PREPARED: PREPARED BY : PROJECT:GE AEROSPACE NORTH GATE IMPROVEMENTS 4/3/2025 DESCRIPTION:PIPE TABLE WSP USA, INC PROJECT NO.US-EI-6260230100 Start Node Stop Node Upstream Inlet Area (acres) System Drainage Area (ft²) Upstream Inlet Tc (hours) Upstream Inlet C Flow (cfs) Slope (Calculated) (ft/ft) Diameter (in) Manning's n Velocity (ft/s) Length (Unified) (ft) Capacity (Full Flow) (cfs) Time (Pipe Flow) (hours) Invert (Start) (ft) Elevation Ground (Start) (ft) Hydraulic Grade Line (In) (ft) Invert (Stop) (ft) Elevation Ground (Stop) (ft) Hydraulic Grade Line (Out) (ft) OPEN END PIPE PROP. DI 0.52 22,659.00 0.117 0.82 5.64 0.005 18 0.013 4.62 158.6 7.41 0.01 27.09 29.25 28.08 26.30 29.16 27.68 PROP. DI PO-01 0.069 25,670.70 0.083 0.86 8.05 0.005 18 0.013 4.56 87.2 7.46 0.005 26.30 29.16 27.61 25.86 28.00 26.96 NOTES: PIPE TABLE (50-YEAR) - PROPOSED CONDITION DATE PREPARED: PREPARED BY : PROJECT:GE AEROSPACE NORTH GATE IMPROVEMENTS 4/3/2025 DESCRIPTION:PIPE TABLE WSP USA, INC PROJECT NO.US-EI-6260230100 Start Node Stop Node Upstream Inlet Area (acres) System Drainage Area (ft²) Upstream Inlet Tc (hours) Upstream Inlet C Flow (cfs) Slope (Calculated) (ft/ft) Diameter (in) Manning's n Velocity (ft/s) Length (Unified) (ft) Capacity (Full Flow) (cfs) Time (Pipe Flow) (hours) Invert (Start) (ft) Elevation Ground (Start) (ft) Hydraulic Grade Line (In) (ft) Invert (Stop) (ft) Elevation Ground (Stop) (ft) Hydraulic Grade Line (Out) (ft) OPEN END PIPE PROP. DI 0.52 22,659.00 0.117 0.82 6.2 0.005 18 0.013 4.69 158.6 7.41 0.009 27.09 29.25 28.21 26.30 29.16 27.78 PROP. DI PO-01 0.069 25,670.70 0.083 0.86 8.63 0.005 18 0.013 4.89 87.2 7.46 0.005 26.30 29.16 27.70 25.86 28.00 27.00 NOTES: PIPE TABLE (100-YEAR) - PROPOSED CONDITION DATE PREPARED: PREPARED BY : PROJECT: 4/3/2025 DESCRIPTION: RRAP-1 GE AEROSPACE ENGINEER: CP RS PROJECT NO. US-EI-6260-23-0100 RS Outlet Flowrate 7.12 cfs Pipe Diameter 18 inches Outlet Pipe Slope 0.5 percent Des. flow velocity 4.45 ft/sec Zone from graph above =1 Outlet Pipe Diameter 18 in.Length =6.0 ft. Outlet Flowrate 7.1 cfs Width =4.5 ft. Outlet Velocity 4.5 ft/sec Max. Stone Dia =6 in. Material =Class A Thickness =9 in. Zone Material Max Stone Dia.Thickness Length Width 1 Class A 6 9 4 x D(o) 3 x D(o) 2 Class B 12 18 6 x D(o) 3 x D(o) 3 Class I 17 26 8 x D(o) 3 x D(o) 4 Class II 23 35 10 x D(o) 3 x D(o) Notes: 1. Calculations based on NY DOT method - Section 8.06.05 through 8.06.06 in NCDENR ESC Manual. CHECKER: DATE PREPARED: GE AEROSPACE NORTH GATE IMPROVEMENTS ENERGY DISSIPATOR DESIGN WORKSHEET WSP USA, Inc. ORIGINATOR: ENGINEER: PREPARED FOR : 4.5 ft/sec 0 5 10 15 20 25 0 1 2 3 4 5 6 7 8 9 10 Ve l o c i t y ( f t / s e c ) Pipe diameter (ft) Figure 8.06.b.1 Zone 1 Zone 2 Zone 3 Zone 4 Zone 5 Zone 6 Zone 7 Page 1 of 1 APPENDIX F NOAA ATLAS 14 RAINFALL DATA