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HomeMy WebLinkAboutComplete BOD-Drainage 072721DRAINAGE REPORT For: Kum & Go, L.C. 6015 Chenonceau Blvd. Little Rock, Pulaski County, AR Prepared For: City of Little Rock, AR Planning and Development 500 West Markham Street Little Rock, AR 72201 Prepared By: Ozark Civil Engineering, Inc. 3214 N.W. Avignon Way, Suite 4 Bentonville, AR 72712 Office: (479) 464-8850 Fax: (479) 464-9040 July 12, 2021 OZARK CIVIL ENGINEERING PROJECT #21-1363 Kum & Go, 2450 BOD-Drainage Report July 12, 2021 PAGE 2 OF 8 DRAINAGE REPORT TABLE OF CONTENTS, LIST OF APPENDICES AND EXHIBITS TABLE OF CONTENTS GENERAL PROJECT DESCRIPTION……………………………………….……….....3 SOIL CLASSIFICATION.…………………………………………………………….….3 DRAINAGE SYSTEMS …..………….……………………………………………….….3 PRE-DEVELOPMENT CONDITIONS……………………………………………….….4 PROPOSED ON-SITE DRAINAGE…….…………………………………………….….5 POST-DEVELOPMENT CONDITIONS………………………………………..……….5 CONCLUSION…………………………………………………………………….……...8 ACKNOWLOGEMENT……………...…………………………………………………..8 APPENDICES APPENDIX-A EXHIBIT I - Vicinity Map EXHIBIT II - Pre-development Drainage Area Map EXHIBIT III - Post-development Drainage Area Map EXHIBIT IV - Post-development Inlet Area Map APPENDIX-B Soils Map & Supporting Design Data APPENDIX-C Pre-development Runoff Calculations APPENDIX-D Post-development Runoff Calculations APPENDIX-E Post-development Pipe/Inlet Calculations Kum & Go, 2450 BOD-Drainage Report July 12, 2021 PAGE 3 OF 8 Kum & Go, 2450 Little Rock, Pulaski County, AR GENERAL Kum & Go, 2450 is a proposed commercial development located at the intersection of Cantrell/Highway-10 and Chenonceau Blvd. (see Exhibit-I). Construction will include a 3,946+ square foot building, fuel canopy with six fuel pumps, drainage, water, sanitary sewer services and site lighting to facilitate on-site parking. The proposed Kum & Go site is located on approximately 1.51 acres. SOIL CLASSIFICATION Information published by the Soil Conservation Service for Pulaski County indicates that the soils found within and around the site are Carnasaw-Urban land complex soils with 3- 8% slopes. The hydrologic soil group for the referenced soils are classified as “C”. DRAINAGE SYSTEMS The on-site drainage system design was performed in accordance with the guidelines set by the City Little Rock’s commercial development regulations. For the underground storm drainage/inlet designs, pre- and post-development runoff analysis; rainfall data was derived from the precipitation frequency intervals taken from NOAA Atlas 14, Volume 9, Version 2. The stormwater analysis for the pre- and post-development peak runoff was completed using Hydraflow Hydrograph software. Peak runoff was calculated using the Rational and Modified Rational Methods. The stormwater analysis for the storm pipe and inlet designs was completed using Hydraflow Storm Sewer software. Peak runoff was calculated using the Standard Rational Method. The Rational and Modified Rational Methods considered land use, time of travel for runoff, rainfall storm events for this area and the size of area (acres) when determining the stormwater runoff. The rainfall amounts vary based on the design storm and on the region of interest. The area was also analyzed to determine its current land use, from which, a Runoff Coefficient (C-Value) was determined for the site. Kum & Go, 2450 BOD-Drainage Report July 12, 2021 PAGE 4 OF 8 PRE-DEVELOPMENT CONDITIONS The 1.51-acre site is currently undeveloped. The site consists of short and/or dense grass and impervious areas. As shown on Exhibit II, the site drainage analysis consists of five (5) drainage basins labeled as “A”, “B”, “C”, “D” and “E”. As shown in Appendix “C”, drainage basin “A” consists of approximately 0.58 acres. Basin “A” slopes from the south property line and outfalls along the north property line. The drainage route for calculating the time of concentration (Tc) for drainage basin “A” includes sheet flow and shallow concentrated flow. The total Tc = 11.9 minutes. The pre- developed weighted Runoff Coefficient Number (C-Value) = 0.35. Drainage basin “B” consists of approximately 0.41 acres. Basin “B” slopes from the south property line and outfalls along the north property line. The drainage route for calculating the time of concentration (Tc) for drainage basin “B” includes sheet flow and shallow concentrated flow. The total Tc = 11.6 minutes. The pre-developed weighted Runoff Coefficient Number (C-Value) = 0.35. Drainage basin “C” consists of approximately 0.12 acres. Basin “C” slopes from the south property line and discharges to an existing area inlet that serves an existing underground detention system. The drainage route for calculating the time of concentration (Tc) for drainage basin “C” includes sheet flow. The total Tc = 11.6 minutes. The pre-developed weighted Runoff Coefficient Number (C-Value) = 0.35. Drainage basin “D” consists of approximately 0.22 acres. Basin “D” slopes from the south property line and outfalls to an existing curb inlet located along the east shared access drive. The drainage route for calculating the time of concentration (Tc) for drainage basin “D” includes sheet flow. The total Tc = 5.0 minutes. This time is considered conservative for this area. The pre-developed weighted Runoff Coefficient Number (C-Value) = 0.62. Drainage basin “E” consists of approximately 0.19 acres. Basin “E” slopes from the south property line and discharges to an existing underground detention system that is currently serving the property to the south. The existing underground detention system will remain and there should not be any additional stormwater added to this system as a result to the proposed Kum & Go development. The drainage route for calculating the time of concentration (Tc) for drainage basin “E” includes sheet flow. The total Tc = 5.0 minutes. This time is considered conservative for the developed area. The pre-developed weighted Runoff Coefficient Number (C-Value) = 0.95. The following table summarizes the peak pre-developed flows from the drainage areas indicated on Exhibit II. Kum & Go, 2450 BOD-Drainage Report July 12, 2021 PAGE 5 OF 8 Outfall Q2 (cfs) Q5 (cfs)Q10(cfs) Q25(cfs) Area "A” & “C”1.0 1.2 1.4 1.6 Area “B”0.6 0.7 0.8 0.9 Area “D”0.8 1.0 1.1 1.3 Area “E”1.1 1.3 1.5 1.7 Site Total 3.5 4.2 4.8 5.5 Table 1. Pre-developed Peak Flows PROPOSED ON-SITE DRAINAGE The drainage scheme for the development is to convey most of the on-site stormwater runoff generated by the Kum & Go site and discharge to an underground detention system located along the north property line. The on-site stormwater will be routed to a series of curb inlets and underground storm pipe and discharge to the proposed underground detention system. The remaining on-site stormwater will be routed around the on-site detention facility, following the pre-development drainage path. The stormwater design for the site is to release runoff at or below the pre-development rate. The post-development runoff was compared to the pre-developed runoff for the 2-year through 25-year storm events. Calculations for the post-developed conditions are in Appendix “D”. Exhibit III is the post-developed drainage map indicating the drainage areas planned for the proposed development. Storm Sewer Design As shown on Exhibit-IV in Appendix E, the development proposes a network of inlets, underground pipe storage and underground storm drainage systems (Systems “A” & “B”). Drainage systems “A” & “B” will convey the stormwater runoff generated from the Kum & Go site and discharge to the underground detention facility; ultimately discharging to the Cantrell/Hwy-10 Right-of-Way, following the pre-development drainage path. Drainage systems “A” & “B” have been designed to contain and transport the runoff for the 10- and 25-year storm events. The drainage was designed so that the depth of the water ponding during the 25-year storm event is limited to the top of curb. POST-DEVELOPMENT CONDITIONS Area “A” consists of approximately 0.29 acres of grass. Detention will not be provided for Area “A”. The drainage route for calculating the time of concentration (Tc) for drainage Kum & Go, 2450 BOD-Drainage Report July 12, 2021 PAGE 6 OF 8 basin “A” includes sheet flow. The total Tc = 5.0 minutes. This time is considered conservative for the developed area. The post-developed weighted C-Value = 0.35. Area “B” consists of approximately 0.12 acres of grass. Detention will not be provided for Area “B”. The drainage route for calculating the time of concentration (Tc) for drainage basin “B” includes sheet flow. The total Tc = 5.0 minutes. This time is considered conservative for the developed area. The post-developed weighted C-Value = 0.35. Area “C” consists of approximately 0.72 acres of grass and impervious material. Area “C” will overland flow from the Kum & Go site to a network of inlets and discharge to an underground detention facility. The proposed underground detention facility will then route the stormwater runoff from the site and outfall to the Cantrell/Hwy-10 Right-of-Way, following the pre-development drainage path. The drainage route for calculating the time of concentration (Tc) for drainage basin “C” includes sheet flow. The total Tc = 5.0 minutes.This time is considered conservative for the developed area. The post-developed weighted C-Value = 0.93. The detention’s outfall structure will consist of a 4-inch orifice, weir and an 8-inch outfall pipe as shown on the outfall structure detail located in Appendix “D”. Area “D” consists of approximately 0.20 acres of grass and impervious material. Detention will not be provided for Area “D”. The drainage route for calculating the time of concentration (Tc) for drainage basin “D” includes sheet flow. The total Tc = 5.0 minutes. This time is considered conservative for the developed area. The post-developed weighted C-Value = 0.65. Area “E” consists of approximately 0.19 acres of impervious material. Detention has already been provided for Area “E”. The existing detention system was previously designed as part of the Chenonceau Commercial Subdivision. The proposed Kum & Go development should not add any additional stormwater runoff to this system. The drainage route for calculating the time of concentration (Tc) for drainage basin “E” includes sheet flow. The total Tc = 5.0 minutes. This time is considered conservative for the developed area. The post-developed weighted C-Value = 0.95. The pre- and post-developed drainage areas are listed below in Table 2. The peak post- developed flows from the development are shown in Table 3. Kum & Go, 2450 BOD-Drainage Report July 12, 2021 PAGE 7 OF 8 Pre-Developed Areas (acre)Post-Developed Areas (acre) Area-A 0.58 Area-A 0.29 Area-B 0.41 Area-B 0.12 Area-C 0.12 Area-C 0.72 Area-D 0.22 Area-D 0.20 Area-E 0.19 Area-E 0.19 TOTAL 1.52 TOTAL 1.52 Table 2. Pre- and Post-developed Areas Outfall Q2 (cfs) Q5 (cfs)Q10 (cfs) Q25 (cfs) A & Cpre-development 1.0 1.2 1.4 1.6 A & Cpost-development (A-Undetained & C-Pond)1.0 1.1 1.2 1.4 Increase/Decrease of Peak 0.0 -0.1 -0.2 -0.2 Bpre-development 0.6 0.7 0.8 0.9 Bpost-development 0.3 0.3 0.3 0.4 Increase/Decrease of Peak -0.3 -0.4 -0.5 -0.5 Dpre-development 0.8 1.0 1.1 1.3 Dpost-development 0.8 0.9 1.0 1.2 Increase/Decrease of Peak 0.0 -0.1 -0.1 -0.1 Epre-development 1.1 1.3 1.5 1.7 Epost-development 1.1 1.3 1.5 1.7 Increase/Decrease of Peak 0.0 0.0 0.0 0.0 Site Totalpre-development 3.5 4.2 4.8 5.5 Site Totalpost-development 3.2 3.6 4.0 4.7 Increase/Decrease of Peak -0.3 -0.6 -0.8 -0.8 Table 3. Pre-developed / Post-developed Peak Flow Kum & Go, 2450 BOD-Drainage Report July 12, 2021 PAGE 8 OF 8 Frequency (years) Detention Volume (ac-ft)Outflow (cfs) Stage (elev.) Pond Bottom --289.20 2 0.023 0.44 290.70 5 0.028 0.48 290.88 10 0.032 0.50 291.02 25 0.037 0.61 291.21 Pond Top --291.70 Table 4. Underground Detention Pond Data CONCLUSION As shown in Table 3, the post-developed peak flows are at or below the pre-developed peak flows for the 2-year through 25-year storm events. The detention’s outfall structure will consist of a 4-inch orifice, weir and an 8-inch outfall pipe. ACKNOWLEDGEMENT Based on the provided data assumptions and calculation assumptions, the proposed stormwater management discharge will not exceed the Pre-developed peak discharge rates from the project. The design, analysis, and their applicability as presented herein is based on and limited by the survey field data and the historical weather data. This development with recommended improvements, if constructed per the site development plans and specifications prepared by Ozark Civil Engineering, Inc., is deemed not to increase existing endangerment to life or property in the surrounding area. Sincerely, Ozark Civil Engineering, Inc. ____________________________________________________________ Michael Clotfelter, Project Manager Todd A. Butler, P.E., CPESC, President APPENDIX – A VICINITY MAP (EXHIBIT – I) PRE-DEVELOPMENT DRAINAGE AREA MAP (EXHIBIT – II) POST-DEVELOPMENT DRAINAGE AREA MAP (EXHIBIT – III) POST-DEVELOPMENT PIPE/INLET MAP (EXHIBIT – IV) Ku m & Go Vicinity Map N.T.S. Legend Chenonc eau Blvd & Cantrell Rd Kum & Go, 2450 500 ft N➤➤N © 2021 Google © 2021 Google © 2021 Google SITE GASGASGASGASGASGAS GAS GAS GAS UGE 8"SS8"SS8"SS8"SS8"SS8"SS8"SSY12"W12"W12"W12"W1 2 "W 12"W8"W 8"W 8"W 8"W FOFOFOFOFO FO FOT T Surveyed Property (Part of Lot 1) 65,739 Square Feet 1.51 Acres Remaining Lot 1 25,929 Square Feet 0.60 Acres 24" RCP 24"RCP 30"CPP 15"CPP18"RCP 15"CPP30"CPP 18"CPPChenoneauBlvd.100'PublicR/WArea inlet Top: 295.4 FL: 290.1 Cantrell Road (ArkansasHwy10) PublicR/WVaries Sanitary manhole Rim:311.12 FL:299.12 (W) FL:299.02 (N) Sanitary manhole Rim:285.97 FL:275.77 (S)Area inlet Top: 286.9 FL: 283.5 Area inlet Top: 285.4 FL: 282.6 Curb inlet Top: 290.5 FL: 286.7(W) FL: 286.6 (E) Area inlet Top: 299.7 FL: 293.9 Curb inlet Top: 286.7 FL: 282.9 Curb inlet Top: 303.8 FL: 299.8 Area inlet Top: 307.0 FL: 299.7 Curb inlet Top: 305.0 FL: 298.5 Area inlet Top: 308.0 FL: 304.0 10' Easement Doc. 96-7594 Exception 15 30'EasementDoc.96-7594 Ex.15 10' Easement Doc. 96-7594 Exception 15 Access Easement Doc. 2004103418 | Exhibit A-1 Exception 19 Access Easement Doc. 2004103418 | Exhibit B-1 Exception 19 Access Easement Doc. 2004103418 | Exhibit A-1 Exception 19 Sanitary manhole Rim:291.73 FL:279.03 (S) FL:278.83 (N) 24"RCP 8"CPPN89°42'29"W 54.80' N88°09'32"W 225.49'Chd:N3°37'35"E52.77'L:52.78'R:1004.93'Chd:N8°03'42"E187.37'L:187.71'R:904.93'Chd: N60° 57' 03"E 36.54' L: 40.97' R: 25.00' S72°06'07"E43.01' S78°06'03"E 143.46' S72° 21' 03"E 51.83' Area inlet Top: 293.9 FL: 289.2 10' Gas Easement Doc. 95-15582 Exception 14 South Line NW 1/4, SE 1/4 Section 14, T02 N, R14 W Parcel ID:53L-014.06-001.00 Owner:Bankcorpsouth Bank Zoned:POD Parcel ID:53L-014.01-002.00 Lot 2 Chenonceau Commercial Add. Owner:Flake Karen/Flake Family Trust Zoned:C3 Existing Shared Development Sign Existing Shared Development Sign N02°07'15"E29.80'N02°07'15"E65.04'S02°58'36"W125.78'S02°58'36"W174.34'N89°01'45"W 212.32'S02° 07' 15"W 5.00' N89°01'45"W 42.01'S19°57'33"W88.78'Curb inlet Top: 291.0 FL: 288.3(S) FL: 287.2 (E) Benchmark № 1 100'Building Line |Doc.96-7594Exception15 40'BuildingLine|Doc.96-7594Exception1530'BufferLine|Doc.96-7594Exception1540'Buffer Line |Doc.96-7594Exception15 Parcel ID:53L-014.06-002.00 Owner:BRSMM 69 INC Zoned:PCD Point of Beginning Area - A = 0.58 acres Grass = 0.15 acres / C-Value = 0.35 Impervious = 0.0 acres / C-Value = 0.95 C-Value = 0.35 Tc = 11.9 min. Area - B = 0.41 acres Grass = 0.41 acres / C-Value = 0.35 Impervious = 0.0 acres / C-Value = 0.95 C-Value = 0.35 Tc = 11.6 min. Sheet Flow L = 150' Slope = 6.8% Shallow Concentrated Flow L = 93.2' Slope = 6.4% Area - A 0.58 acres Area - B 0.41 acres Area - C 0.12 acres Area - D 0.22 acres Area - E 0.19 acres Area - C = 0.12 acres Grass = 0.12 acres / C-Value = 0.35 Impervious = 0.0 acres / C-Value = 0.95 C-Value = 0.35 Tc = 11.6 min. Area - D = 0.22 acres Grass = 0.12 acres / C-Value = 0.35 Impervious = 0.10 acres / C-Value = 0.95 C-Value = 0.62 Tc = 5.0 min. Area - E = 0.19 acres Grass = 0.0 acres / C-Value = 0.35 Impervious = 0.19 acres / C-Value = 0.95 C-Value = 0.95 Tc = 5.0 min. Sheet Flow L = 150' Slope = 7.3% Shallow Concentrated Flow L = 91.1' Slope = 6.3% Sheet Flow L = 160' Slope = 7.6% SHEET №3214N.W.AVIGNONWAY,SUITE4  BENTONVILLE,AR72712  479.464.8850|OFFICE  479.464.9040|FAX1 A B C D E F G H I J K 2 3 4 5 6 7 8 9 10 11 12 13 14 15 A B C D E F G H I J K 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 DESCRIPTION: ORIGINAL ISSUE DATE: JOB № DRAWN BY: № REVISIONS: DATE DESCRIPTION PRE-DEVELOPMENTDRAINAGEAREAMAPKUM&GO,24506015CHENONCEAUBLVD.LITTLEROCK,PULASKICO.,ARMRC 06-14-2021 SCALE - 1:30 21-1363 c:\dropbox(ozarkcivil)\tscprojects\15-1173cordellok\design\drainagereport\pre-development.dwg-Plottedon----topdf-xchange4.0.pc3byMClotfelterGRAPHIC SCALE IN FEET | 1in = 30ft 30 60 900153015 N S EW NW NE SW SE GASGASGASGASGASGAS GAS GAS GAS UGE 8"SS8"SS8"SS8"SS8"SS8"SS8"SSY12"W12"W12"W12"W1 2 "W 12"W8"W 8"W 8"W 8"W FOFOFOFOFO FO FOT T Remaining Lot 1 25,929 Square Feet 0.60 Acres 24" RCP 24"RCP 30"CPP 15"CPP18"RCP 15"CPP30"CPP 18"CPPChenoneauBlvd.100'PublicR/WArea inlet Top: 295.4 FL: 290.1 Cantrell Road (ArkansasHwy10) PublicR/WVaries Sanitary manhole Rim:311.12 FL:299.12 (W) FL:299.02 (N) Sanitary manhole Rim:285.97 FL:275.77 (S)Area inlet Top: 286.9 FL: 283.5 Area inlet Top: 285.4 FL: 282.6 Curb inlet Top: 290.5 FL: 286.7(W) FL: 286.6 (E) Area inlet Top: 299.7 FL: 293.9 Curb inlet Top: 286.7 FL: 282.9 Curb inlet Top: 303.8 FL: 299.8 Area inlet Top: 307.0 FL: 299.7 Curb inlet Top: 305.0 FL: 298.5 Area inlet Top: 308.0 FL: 304.0 10' Easement Doc. 96-7594 Exception 15 30'EasementDoc.96-7594 Ex.15 10' Easement Doc. 96-7594 Exception 15 Access Easement Doc. 2004103418 | Exhibit A-1 Exception 19 Access Easement Doc. 2004103418 | Exhibit B-1 Exception 19 Access Easement Doc. 2004103418 | Exhibit A-1 Exception 19 Sanitary manhole Rim:291.73 FL:279.03 (S) FL:278.83 (N) 24"RCP 8"CPPN89°42'29"W 54.80' N88°09'32"W 225.49'Chd:N3°37'35"E52.77'L:52.78'R:1004.93'Chd:N8°03'42"E187.37'L:187.71'R:904.93'Chd: N60° 57' 03"E 36.54' L: 40.97' R: 25.00' S72°06'07"E43.01' S78°06'03"E 143.46' S72° 21' 03"E 51.83' Area inlet Top: 293.9 FL: 289.2 10' Gas Easement Doc. 95-15582 Exception 14 South Line NW 1/4, SE 1/4 Section 14, T02 N, R14 W Parcel ID:53L-014.06-001.00 Owner:Bankcorpsouth Bank Zoned:POD Parcel ID:53L-014.01-002.00 Lot 2 Chenonceau Commercial Add. Owner:Flake Karen/Flake Family Trust Zoned:C3 Existing Shared Development Sign Existing Shared Development Sign N02°07'15"E29.80'N02°07'15"E65.04'S02°58'36"W125.78'S02°58'36"W174.34'N89°01'45"W 212.32'S02° 07' 15"W 5.00' N89°01'45"W 42.01'S19°57'33"W88.78'Curb inlet Top: 291.0 FL: 288.3(S) FL: 287.2 (E) Benchmark № 1 Parcel ID:53L-014.06-002.00 Owner:BRSMM 69 INC Zoned:PCD Point of Beginning 2620KUNLEADED12KDIESEL512KPREMIUMFV412KE-85FVFVFV2 "WTR 2"WTR2"WTRUGEUGE UGE UGE UGE UGE UGEUGTUGTUGTUGT3.76%2 .3 6 % 1.99%2.00% 1 .7 4 % 4.29% 4.79%5.28% 3 .6 1 %3.0 4 %3.86%4 .2 5 %1.55%1 .4 1 % 2.5:12.5:12.5:12.5:12.5:12.5:1 1.62%4.34%2 .3 6 % 1.75%5.44%3.0:1 2.50%3.33%2.00%1.86% 5.62% 1.83% 2 .9 0 % 1.76%1.53% D D 3.14% 2.00% 1.83% ep 308.31 ep 308.31 307.95 307.91 306.98 305.89 307.30 306.44 g 308.30 g 308.34 ep 308.49 tg 308.35 ep 308.44 ep 308.43ep 308.43 tg 308.35 ep 308.44 ep 308.44ep 308.44 ep 308.44ep 308.34 ep 308.23 ep 307.71 ep 308.47 ep 308.44ep 308.66 ep 308.33 ep 307.81 ep 307.40 ep 307.49 ep 308.46 g 308.31 g 308.34 ep 308.31 ep 308.44 ep 308.44 ep 308.30 ep 308.44 ep 308.44 ep 308.44 ep 308.31 ep 305.85 ep 306.44 ep 306.34 ep 306.41 306.08 306.35 g 306.20 g 305.88 307.93 307.92 307.17 307.12ep 308.44 tc 308.22tc 308.33 g 306.02g 306.06 1.87% Area - A 0.29 acres Area - B 0.12 acres Area - C 0.72 acres Area - D 0.20 acres Area - E 0.19 acres Area - A = 0.29 acres Grass = 0.29 acres / C-Value = 0.35 C-Value = 0.35 Tc = 5.0 min. Area - B = 0.12 acres Grass = 0.12 acres / C-Value = 0.35 C-Value = 0.35 Tc = 5.0 min. Area - C = 0.72 acres Grass = 0.02 acres / C-Value = 0.35 Impervious = 0.70 acres / C-Value = 0.95 C-Value = 0.93 Tc = 5.0 min. Area - D = 0.20 acres Grass = 0.10 acres / C-Value = 0.35 Impervious = 0.10 acres / C-Value = 0.95 C-Value = 0.65 Tc = 5.0 min. Area - E = 0.19 acres Grass = 0.0 acres / C-Value = 0.35 Impervious = 0.19 acres / C-Value = 0.95 C-Value = 0.95 Tc = 5.0 min. SHEET №3214N.W.AVIGNONWAY,SUITE4  BENTONVILLE,AR72712  479.464.8850|OFFICE  479.464.9040|FAX1 A B C D E F G H I J K 2 3 4 5 6 7 8 9 10 11 12 13 14 15 A B C D E F G H I J K 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 DESCRIPTION: ORIGINAL ISSUE DATE: JOB № DRAWN BY: № REVISIONS: DATE DESCRIPTION POST-DEVELOPMENTDRAINAGEAREAMAPKUM&GO,24506015CHENONCEAUBLVD.LITTLEROCK,PULASKICO.,ARMRC 06-14-2021 SCALE - 1:30 21-1363 c:\dropbox(ozarkcivil)\tscprojects\15-1173cordellok\design\drainagereport\pre-development.dwg-Plottedon----topdf-xchange4.0.pc3byMClotfelterGRAPHIC SCALE IN FEET | 1in = 30ft 30 60 900153015 N S EW NW NE SW SE GASGASGASGASGASGASGASGAS GAS GAS GAS GAS GAS GAS UGE U G E 8"SS 8"SS8"SS8"SS8"SS8"SS8"SS8"SS8"SS8"SSY12"W12"W12"W12"W12"W12"W1 2 "W 12"W 12"W8"W 8"W 8"W 8"W 8"W 8"W FOFOFOFOFOFOFOFO FO FO FOT T Surveyed Property (Part of Lot 1) 65,739 Square Feet 1.51 Acres Remaining Lot 1 25,929 Square Feet 0.60 Acres 24" RCP 24"RCP 30"CPP 15"CPP18"RCP 15"CPP30"CPP 18"CPPChenoneauBlvd.100'PublicR/WArea inlet Top: 295.4 FL: 290.1 Cantrell Road (ArkansasHwy10) PublicR/WVaries Sanitary manhole Rim:311.12 FL:299.12 (W) FL:299.02 (N) Sanitary manhole Rim:285.97 FL:275.77 (S)Area inlet Top: 286.9 FL: 283.5 Area inlet Top: 285.4 FL: 282.6 Curb inlet Top: 290.5 FL: 286.7(W) FL: 286.6 (E) Area inlet Top: 299.7 FL: 293.9 Curb inlet Top: 286.7 FL: 282.9 Curb inlet Top: 303.8 FL: 299.8 Area inlet Top: 307.0 FL: 299.7 Curb inlet Top: 305.0 FL: 298.5 Area inlet Top: 308.0 FL: 304.0 10' Easement Doc. 96-7594 Exception 15 30'EasementDoc.96-7594 Ex.15 10' Easement Doc. 96-7594 Exception 15 Access Easement Doc. 2004103418 | Exhibit A-1 Exception 19 Access Easement Doc. 2004103418 | Exhibit B-1 Exception 19 Access Easement Doc. 2004103418 | Exhibit A-1 Exception 19 Sanitary manhole Rim:291.73 FL:279.03 (S) FL:278.83 (N) 24"RCP 8"CPPChd:N3°37'35"E52.77'L:52.78'R:1004.93'Chd:N8°03'42"E187.37'L:187.71'R:904.93'Chd: N60° 57' 03"E 36.54' L: 40.97' R: 25.00' S72°06'07"E43.01' S78°06'03"E 143.46' S72° 21' 03"E 51.83' Area inlet Top: 293.9 FL: 289.2 10' Gas Easement Doc. 95-15582 Exception 14 Parcel ID:53L-014.06-001.00 Owner:Bankcorpsouth Bank Zoned:POD Existing Shared Development Sign Existing Shared Development Sign N02°07'15"E29.80'N02°07'15"E65.04'S02°58'36"W125.78'S02°58'36"W174.34'N89°01'45"W 212.32' S02° 07' 15"W 5.00' N89°01'45"W 42.01'S19°57'33"W88.78'Curb inlet Top: 291.0 FL: 288.3(S) FL: 287.2 (E) Benchmark № 12620KUNLEADED12KDIESEL512KPREMIUMFV412KE-85FVFVFVUGEUGEUGE UGE UGE UGE UGE UGE UGE U G E UGEUGEUGTUGTUGTUGTUGTUGTPROPOSEDKUM&GO STOREBISTRO-RP-2021V13,968 SF F.F.E.=308.44 RPZRPZ±162 LF SEGMENTALRETAININGWALL(REF.TO PLANS BY OTHERS) D D STRUCT: C-1 48" CURB INLET 4' CURB OPENING TOP / RIM: 307.61 SW IE. IN: 303.44 | 10" HDPE N IE. OUT: 302.77 | 18" PIPE STRUCT: A-3 48" CURB INLET 4' CURB OPENING TOP / RIM: 306.31 S IE. IN: 298.95 | 18" PIPE NE IE. OUT: 298.95 | 18" PIPE STRUCT: A-4 48" CURB INLET 4' CURB OPENING TOP / RIM: 305.57 S IE. IN: 299.50 | 18" PIPE W IE. IN: 299.50 | 18" PIPE N IE. OUT: 299.50 | 18" PIPE STRUCT: A-5 4'X6' DROP INLET NEENAH R-1878-B8G TOP / RIM: 304.23 N IE. OUT: 300.00 | 18" PIPE STRUCT: B-1 48" DRAINAGE MANHOLE TOP / RIM: 306.60 W IE. IN: 302.42 | 18" PIPE N IE. IN: 304.96 | 10" HDPE S IE. IN: 304.31 | 10" HDPE E IE. OUT: 302.42 | 18" PIPE STRUCT: B-2 48" DRAINAGE MANHOLE TOP / RIM: 308.04 W IE. IN: 305.10 | 6" HDPE S IE. IN: 304.11 | 18" PIPE E IE. OUT: 304.11 | 18" PIPE STRUCT: B-3 48" CURB INLET 4' CURB OPENING TOP / RIM: 308.25 N IE. OUT: 304.50 | 18" PIPE 166 LF 30" CORR. HDPE @ 0.54% 166 LF 30" CORR. HDPE @ 0.54% 153 LF 10" HDPE @ ??? MIN. STRUCT:A-2 CONTRACTOR SHALLREMOVEEXISTINGAREAINLET&INSTALL NEW 12'X4'J-BOXTOP/RIM:301.12SWIE.IN:296.78 |18"PIPEWIE.OUT:290.10 |30"C.HDPEWIE.OUT:290.10 |30"C.HDPEWIE.OUT:290.10 |30"EXIST.CPP STRUCT:A-1 CONTRACTOR SHALLREMOVEEXISTINGAREAINLET&INSTALL NEW 12'X4'J-BOXTOP/RIM:300.66SWIE.IN:301.05 |18"PIPEEIE.IN:289.20 |30"C.HDPEEIE.IN:289.20 |30"C.HDPEEIE.IN:289.20 |30"EXIST.CPPNWIE.OUT:289.20 |8"EXIST.CPP 4" HDPE 4" HDPE 4" HDPE4" HDPE 4" HDPE4" HDPE CONTRACTOR SHALL ADJUSTAREAINLETTOPTOMATCHPROPOSEDGRADESTOP/RIM:307.80 CI-1 Area = 0.10 C-Value = 0.93 Tc = 5.0 min. Roof Drain (R) Area = 0.06 C-Value = 0.98 Tc = 5.0 min. CI-2 Area = 0.13 C-Value = 0.93 Tc = 5.0 min. CI-3 Area = 0.09 C-Value = 0.93 Tc = 5.0 min. GI-4 Area = 0.19 C-Value = 0.93 Tc = 5.0 min. CI-5 Area = 0.03 C-Value = 0.93 Tc = 5.0 min. Roof Drain (F) Area = 0.03 C-Value = 0.98 Tc = 5.0 min. JB JB Canopy Drain Area = 0.07 C-Value = 0.98 Tc = 5.0 min. SHEET №3214N.W.AVIGNONWAY,SUITE4  BENTONVILLE,AR72712  479.464.8850|OFFICE  479.464.9040|FAX1 A B C D E F G H I J K 2 3 4 5 6 7 8 9 10 11 12 13 14 15 A B C D E F G H I J K 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 DESCRIPTION: ORIGINAL ISSUE DATE: JOB № DRAWN BY: № REVISIONS: DATE DESCRIPTION POST-DEVELOPMENTINLETAREAMAPKUM&GO,24506015CHENONCEAUBLVD.LITTLEROCK,PULASKICO.,ARMRC 06-21-2021 SCALE - 1:20 21-1363 c:\dropbox(ozarkcivil)\tscprojects\15-1173cordellok\design\drainagereport\pre-development.dwg-Plottedon----topdf-xchange4.0.pc3byMClotfelter0 N S EW NW NE SW SE GRAPHIC SCALE IN FEET | 1in = 20ft 20 40 60102010 APPENDIX – B SOILS MAP & SUPPORTING DESIGN DATA Soil Map—Pulaski County, Arkansas (KUM & GO, 2450 - LITTLE ROCK, AR) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 6/24/2021 Page 1 of 3385177038517803851790385180038518103851820385183038518403851850385186038518703851880385177038517803851790385180038518103851820385183038518403851850385186038518703851880548570548580548590548600548610548620548630548640548650548660548670548680548690548700548710548720548730548740 548570 548580 548590 548600 548610 548620 548630 548640 548650 548660 548670 548680 548690 548700 548710 548720 548730 548740 34° 48' 28'' N 92° 28' 8'' W34° 48' 28'' N92° 28' 1'' W34° 48' 25'' N 92° 28' 8'' W34° 48' 25'' N 92° 28' 1'' WN Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 15N WGS84 0 40 80 160 240 Feet 0 10 20 40 60 Meters Map Scale: 1:832 if printed on A landscape (11" x 8.5") sheet. Soil Map may not be valid at this scale. MAP LEGEND MAP INFORMATION Area of Interest (AOI) Area of Interest (AOI) Soils Soil Map Unit Polygons Soil Map Unit Lines Soil Map Unit Points Special Point Features Blowout Borrow Pit Clay Spot Closed Depression Gravel Pit Gravelly Spot Landfill Lava Flow Marsh or swamp Mine or Quarry Miscellaneous Water Perennial Water Rock Outcrop Saline Spot Sandy Spot Severely Eroded Spot Sinkhole Slide or Slip Sodic Spot Spoil Area Stony Spot Very Stony Spot Wet Spot Other Special Line Features Water Features Streams and Canals Transportation Rails Interstate Highways US Routes Major Roads Local Roads Background Aerial Photography The soil surveys that comprise your AOI were mapped at 1:20,000. Warning: Soil Map may not be valid at this scale. Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed scale. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Pulaski County, Arkansas Survey Area Data: Version 17, Jun 9, 2020 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: Jul 14, 2018—Aug 1, 2018 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. Soil Map—Pulaski County, Arkansas (KUM & GO, 2450 - LITTLE ROCK, AR) Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 6/24/2021 Page 2 of 3 Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI CbC Carnasaw-Urban land complex, 3 to 8 percent slopes 1.9 100.0% Totals for Area of Interest 1.9 100.0% Soil Map—Pulaski County, Arkansas KUM & GO, 2450 - LITTLE ROCK, AR Natural Resources Conservation Service Web Soil Survey National Cooperative Soil Survey 6/24/2021 Page 3 of 3 g§°°'Q.Location name:Little Rock,Arkansas,USA*5"’“*3; _3 Latitude:34.8077“,Longitude:-92.4682’=E :E""~..9’; NOAA Atlas 14,Volume 9,Version 2 ‘ma $gr Elevation:305.29 ft** mm "9"*source:ESRI Maps r_ ’source:USGS '“""‘ mm- POINT PRECIPITATION FREQUENCY ESTIMATES Sanja Perica,Deborah Martin,Sandra Pavlovic,lshani Roy,Michael St.Laurent,Carl Trypaluk,Dale Unruh,Michael Yekta,Geoffery Bonnin NOAA,National Weather Service,Silver Spring,Maryland PF_tabular|PF_g@phical |Maps_&_aerials PF tabular PDS-based point precipitation frequency estimates with 90%confidence intervals (in inchesIhour)1 Duration Average recurrence interval (years) 1 2 5 10 25 50 100 200 500 1000 5-min 5.32 (4.28-8.60) 6.02 (4.85-7.48) 7.14 (5.72-8.88) 8.04 (8.42-10.1) 9.25 (7.13-11.9) 10.2 (7.66-13.2) 11.0 (8.05-14.8) 11.9 (8.35-18.4) 13.0 (8.80-18.5) 13.8 (9.12-20.0) 10-min 3.89 (3.14-4.83) 4.41 (3.55-5.47) 5.23(4.19-6.50)5.89 (4.70-7.36) 6.77 (5.22-8.69) 7.43 (5.61 -9.70) 8.08 (5.90-10.8) 8.71 (6.11-12.0) 9.51 (6.44-13.5) 10.1 (6.68-14.7) 15-min 3.16 (2.55-3.92) 3.58 (2.88-4.45) 4.25 (3.41 -5.29) 4.79 (3.82-5.99) 5.50 (4.24-7.07) 6.04 (4.56-7.89) 6.56 (4.80-8.80) 7.08 (4.97-9.77) 7.73 (5.23-11.0) 8.21 (5.43-11.9) 30-min 2.35 (1 .89-2.91) 2.67 (2.15-3.31) 3.17 (2.55-3.95) 3.58 (2.86-4.48) 4.12 (3.17-5.28) 4.51 (3.40-5.89) 4.90 (3.57-6.55) 5.27 (3.70-7.26) 5.74 (3.88-8.15) 6.07 (4.02-8.82) 60-min 1.56 (1.26-1.94) 1.77 (1 .43-2.20) 2.10 (1.69-2.62) 2.37 (1.89-2.97) 2.74 (2.11-3.52) 3.01 (2.27-3.93) 3.28(2.39-4.39)3.54 (2.49-4.89) 3.88(2.63-5.53) 4.14 (2.74-6.01) 2-hr 0.978 (0.793-1.20) 1.10 (0.895-1.36) 1.31 (1.06-1.62) 1.48 (1.19-1.84) 1.71 (1.33-2.18) 1.88 (1 .43-2.44) 2.05 (1 .51-2.74) 2.22 (1 .57-3.06) 2.45 (1 .67-3.47) 2.62 (1.74-3.78) 3-hr 0.734 (0.597-0.900) 0.827 (0.673-1.02) 0.981 (0.795-1.21) 1.11 (0.894-1.37) 1.29 (1.01-1.65) 1.43 (1.09-1.85) 1.57 (1.16-2.09) 1.71 (1.22-2.34) 1.90 (1 .30-2.68) 2.04 (1.37-2.94) 6-hr 0.443 (0.363-0.540) 0.501(0.410-0.612)0.600(0.489-0.734)0.684 (0.556-0.342) 0.806 (0.636-1.03) 0.903 (0.696-1.17) 1.00 (0.749-1.33) 1.11 (0.795-1.52) 1.25 (0.866-1.76) 1.37 (0.919-1.95) 12-hr 0.261 (0.216-0.317) 0.299 (0.246-0.362) 0.363 (0.298-0.441) 0.420 (0.343-0.513) 0.502 (0.400-0.639) 0.570 (0.443-0.735) 0.640 (0.481-0.348) 0.715 (0.517-0.974) 0.820 (0.571-1.15) 0.902 (0.611-1.28) 24-hr 0.154 (0.128-0.185) 0.177 (0.147-0.214) 0.218 (0.180-0.263) 0.254 (0.209-0.308) 0.306 (0.246-0.388) 0.350 (0.274-0.449) 0.396 (0.300-0.521) 0.445 (0.324-0.603) 0.513 (0.360-0.716) 0.568 (0.387-0.801) 2-day 0.090 (0.075-0.107) 0.103 (0.086-0.123) 0.126 (0.105-0.152) 0.147 (0.122-0.177) 0.177 (0.143-0.228) 0.202 (0.159-0.258) 0.229 (0.174-0.299) 0.257 (0.188-0.346) 0.296 (0.209-0.411) 0.328 (0.225-0.460) 3-day 0.065 (0.055-0.078) 0.075 (0.063-0.089) 0.091 (0.076-0.109) 0.105 (0.088-0.126) 0.126 (0.102-0.158) 0.144 (0.114-0.182) 0.162 (0.124-0.211) 0.181 (0.133-0.243) 0.208 (0.147-0.287) 0.229 (0.158-0.320) 4-day 0.052 (0.044-0.062) 0.060 (0.050-0.071) 0.072 (0.061-0.086) 0.083 (0.069-0.100) 0.099 (0.081-0.124) 0.113 (0.089-0.142) 0.126 (0.097-0.164) 0.141 (0.104-0.188) 0.161 (0.115-0.222) 0.177 (0.123-0.247) 7-day 0.035 (0.029-0.041) 0.039 (0.033-0.046) 0.047 (0.040-0.056) 0.054 (0.045-0.064) 0.063 (0.052-0.079) 0.071 (0.057-0.089) 0.079 (0.061-0.102) 0.088 (0.065-0.117) 0.100 (0.071-0.136) 0.109 (0.076-0.151) 10-day 0.027 (0.023-0.032) 0.031 (0.026-0.036) 0.036 (0.031-0.043) 0.041 (0.035-0.049) 0.048 (0.039-0.059) 0.054 (0.043-0.067) 0.060 (0.046-0.076) 0.066 (0.049-0.086) 0.074 (0.053-0.100) 0.080 (0.056-0.110) 20-day 0.019 (0.016-0.022) 0.020 (0.017-0.024) 0.023 (0.020-0.028) 0.026 (0.022-0.031) 0.030 (0.024-0.036) 0.032 (0.026-0.040) 0.035 (0.027-0.045) 0.038 (0.028-0.050) 0.042 (0.030-0.056) 0.045 (0.032-0.062) 30-day 0.015 (0.013-0.019) 0.016 (0.014-0.019) 0.019 (0.016-0.022) 0.021 (0.018-0.024) 0.023 (0.019-0.029) 0.025 (0.020-0.031) 0.027 (0.021-0.034) 0.029 (0.022-0.038) 0.032 (0.023-0.043) 0.034 (0.024-0.046) 45-day 0.012 (0.010-0.014) 0.013 (0.012-0.016) 0.015 (0.013-0.018) 0.017 (0.015-0.020) 0.019 (0.016-0.023) 0.021 (0.017-0.025) 0.022 (0.017-0.028) 0.024 (0.018-0.031) 0.026 (0.019-0.035) 0.027 (0.019-0.037) 60-day 0.010 (0.009-0.012) 0.012 (0.010-0.013) 0.013 (0.012-0.016) 0.015 (0.013-0.017) 0.017 (0.014-0.020) 0.018 (0.015-0.022) 0.020 (0.016-0.025) 0.021 (0.016-0.027) 0.023 (0.017-0.031) 0.024 (0.017-0.033) 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 Top PF graphical nsty(in/hr) FIIIIE Precptaton tenstyt'n.lhr) Precptatonn NQAA A335 14_\;0|um9 9,Vefgign 3 Created (GMT):Thu jun 24 20:29:39 2021 PDS-based intensity-duration-frequency (IDF)curves Latitude:34.8077”,Longitude:-92.4632" 100.00 ...................._ eeee 2 iiii _ eeee aaaa eeee aaaa eeee aaaa -2 2 2 2 2 2 2 2 2 2 2.2.2 2 — 22 2 2 22 2 2 2 222 5._ 7 IIIIIIIIIIIIIIIII 0.01 E E 0'1 10-mn 15-mn 30-mn 60-mn 2-hr 3-hr 6-hr 12-hr Duration 100.00 ,,,, 24-hr 2-day 3-day 4-day 7-day 10-day 20-day_30-day_45-d 60-dgiiIII ._._...:..._._._....;_._...-4-: Average recurrence interval (years) 1 2 5 10 25 50 100 200 500 1000 ___I--—-7‘-“___}f 2 Duration __',—I . r #_.- 1_0D T-.—_~1T ........_._-_........_......_...... ..._.___—-|-....___.__——..._|_ ____.___-———._.7r .. I I i[]_]_(]............ -1*'; J_ .4 .. J r - 0.01 +2”2 2III I I I I 1 2 5 10 25 50 100 200 Average recurrence interval (years) Back to Top Maps &aerials Small scale terrain 500 1000 5-min 10-min 15-mm 30-mm 60-min 2-hr 3-hr 6-hr 12-hr 24-hr 2-day 3-day 4-day 7-day 10-day 20-day 30-day 45-day 60-day Large scale map-_.-*__"\I,-_ .;I2 1;; ‘I -\'._1"IF I 2m|F_',I ...'':1-I ._,1- ‘-.|I1:-_-.n ______;I_IIq —:1 .__ -»=‘212;2;... .i>*I,»._~..!+--'--'._-.'§~.__‘.q ..'---'._-P --__.-.FI '.'1.-..-.._1,-__fi_)A 5 ‘ ',.-i§9‘2‘“i-3%"_1 ‘grip _-fl.—:__in '~- '“-._—-__ L€;@i§F¥-I 1.5 -."(._.1 _t_)"l.‘2 §1,'.*\_...- r'I '.2'"'‘2 2 ~:|1-100km .*'"-.llie1-2 I_60mi ._ H - Large scale aerial Back to Top US Department of Commerce National Oceanic and Atmospheric Administration National Weather Service National Water Center 1325 East West Highway Silver Spring,MD 20910 Questions?:HDSC.Questions@noaa.gg Disclaimer _Y 8 Lat|tude.34.8077,Long|tude.92.4682 g§"“°°'Q.Location name:Little Rock,Arkansas,USA* %‘¢,~>'g *source:ESRI l\I|aps NOAA Atlas 14,Volume 9,Version 2 M Elevation 305 29 ft**mm- ms source:USGS '“""I. POINT PRECIPITATION FREQUENCY ESTIMATES Sanja Perica,Deborah Martin,Sandra Pavlovic,lshani Roy,Michael St.Laurent,Carl Trypaluk,Dale Unruh,Michael Yekta,Geoffery Bonnin NOAA,National Weather Service,Silver Spring,Maryland PF_tabular|PF_g@phical |Maps_&_aerials PF tabular PDS-based point precipitation frequency estimates with 90%confidence intervals (in inches)1 Duration Average recurrence interval (years) 1 2 5 10 25 50 100 200 500 1000 5-min 0.443 (0.357-0.550) 0.502 (0.404-0.623) 0.595 (0.477-0.740) 0.670 (0.535-0.838) 0.771 (0.594-0.990) 0.846 (0.638-1.10) 0.919 (0.671-1.23) 0.991 (0.696-1.37 ) 1.08 (0.733-1.54 ) 1.15 (0.760-1.67 ) 10-min 0.649 (0.523-0.805) 0.735 (0.591-0.912) 0.871 (0.699-1.08) 0.981 (0.783-1.23) 1.13 (0.870-1.45) 1.24 (0.935-1.62) 1.35 (0.983-1.80) 1.45 (1.02-2.00) 1.59 (1 .07-2.26) 1.68 (1 .11-2.45) 15-min 0.791(0.638-0.981)0.896 (0.721-1.11) 1.06 (0.852-1.32) 1.20 (0.955-1.50) 1.38 (1 .06-1.77) 1.51 (1.14-1.97) 1.64 (1 .20-2.20) 1.77 (1 .24-2.44) 1.93 (1.31-2.75) 2.05 (1 .36-2.98) 30-min 1.17 (0.945-1.45) 1.33 (1 .07-1.65) 1.59 (1 .27-1.97) 1.79 (1 .43-2.24) 2.06 (1 .58-2.64) 2.26 (1 .70-2.94) 2.45 (1 .79-3.28) 2.63 (1 .85-3.63) 2.87 (194408) 3.04 (2.01-4.41) 60-min 1.56 (1 .26-1 .94) 1.77 (1 .43-2.20) 2.10 (1 .69-2.62) 2.37 (1 .89-2.97) 2.74 (2.11-3.52) 3.01 (2.27-3.93) 3.28(2.39-4.39)3.54 (2.49-4.89) 3.88(2.63-5.53)4.14 (2.74-6.01) 2-hr 1.96 (1 .59-2.41) 2.21 (1 .79-2.72) 2.62 (2.12-3.24) 2.96 (2.37-3.67) 3.41(265436)3.76 (2.86-4.89) 4.10 (3.02-5.48) 4.45 (3.15-6.11) 4.90 (3.34-6.93) 5.23 (3.48-7.56) 3-hr 2.20 (1 .79-2.70) 2.48 (2.02-3.05) 2.95 (2.39-3.63) 3.33 (2.69-4.12) 3.87 (302494) 4.28 (3.27-5.56) 4.70 (3.48-6.26) 5.13 (3.65-7.04) 5.70 (3.91 -8.06) 6.14 (4.10-8.83) 6-hr 2.65(2.17-3.24)3.00(2.46-3.66)3.59(2.93-4.39)4.10 (3.33-5.04) 4.82 (3.81-6.15)5.41(4.17-7.00)6.01(4.48-7.98)6.64(4.76-9.08)7.50 (5.18-10.6)8.18(5.50-11.7) 12-hr 3.15(2.60-3.82)3.60(2.97-4.36)4.37(3.59-5.32)5.06(4.13-6.18)6.05(4 .82-7.70)6.86(5.33-8.85)7.71(5.80-10.2)8.62(6.23-11.7)9.88(6.87-13.8)10.9(7.36-15.4) 24-hr 3.70 (307445) 4.26 (3.58-5.13) 5.23 (4.32-6.31) 6.09 (5.01-7.39) 7.36 (5.90-9.82) 8.40 (6.58-10.8) 9.50 (7.20-12.5) 10.7 (7.77-14.5) 12.3 (8.64-17.2) 13.6 (9.30-19.2) 2-day 4.31 (3.60-5.15) 4.95 (4.13-5.92) 6.06(5.05-7.27) 7.05 (5.84-8.50)8.51(6.88-10.7)9.71 (7.66-12.4) 11.0 (8.38-14.4) 12.3 (9.04-16.6) 14.2 (10.0-19.7) 15.7 (10.8-22.1) 3-day 4.70(3.94-5.59)5.37(4.51-6.40)6.54(5.47-7.82)7.58(6.30-9.10)9.10(7.37-11.4)10.3(8.18-13.1)11.6(8.91-15.2)13.0(9.59-17.5)15.0(10.6-20.7)16.5(11.4-23.1) 4-day 5.01 (4.22-5.95) 5.71 (4.81-6.79) 6.93 (5.81-8.26) 7.99 (6.67-9.57) 9.54 (7.75-11.9) 10.8 (8.57-13.7) 12.1 (9.31-15.7) 13.5 (9.98-18.1) 15.5 (11.0-21.3) 17.0 (11.8-23.7) 7-day 5.81(4.92-6.86)6.58(5.57-7.78) 7.89 (6.66-9.36)9.03(7.58-10.8)10.7 (8.70-13.2) 12.0 (9.55-15.0) 13.3 (10.3-17.2) 14.8(10.9-19.6)16.8 (12.0-22.9) 18.3 (12.7-25.3) 10-day 6.57 (5.59-7.74) 7.38(6.27-8.70)8.75(7.40-10.3)9.92(8.35-11.8)11.6(9.47-14.3)12.9(10.3-16.1)14.3(11.0-18.3)15.7(11.7-20.7)17.7(12.6-24.0)19.2(13.4-26.5) 20-day 8.92 (7.64-10.4) 9.80 (8.38-11.5) 11.3 (9.59-13.2) 12.5 (10.6-14.7) 14.2 (11.7-17.3) 15.5 (12.5-19.2) 16.9 (18.1-21.4) 18.3 (13.7-23.9) 20.1 (14.5-27.1) 21.6 (15.1-29.5) 30-day 10.8 (9.31-12.6) 11.9 (10.2-13.8) 13.5 (11.6-15.8) 14.9 (12.7-17.5) 16.8(13.8-20.3)18.2 (14.7-22.4) 19.7 (15.4-24.8) 21.1 (15.9-27.5) 23.1(16.7-30.9)24.5 (17.3-33.4) 45-day 13.1(11.3-15.2)14.5(12.5-16.8)16.6(14.3-19.3)18.4(15.7-21.5)20.7(17.1-24.8)22.4(18.1-27.4)24.1(13.9-30.3)25.8(19.4-33.4)28.0(20.3-37.3)29.6(20.9-40.2) 60-day 15.0(13.0-17.3)16.7(14.4-19.3)19.4 (16.7-22.5) 21.6 (18.5-25.2) 24.4(20.2-29.2)26.6(21 .5-32.3)28.6(22.4-35.7)30.6(23.1-39.4)33.2(241439)35.0(24.8-47.4) 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 Top PF graphical PDS-based depth—duration-frequency (DDF)curves Latitude:34.8077”.Longitude:-92.4682" 35|1i||1i||1|||1i1 3 J AVEFBQB TBCU ITBHCE 30--.;............"";.......".-'interval depthl'nl Precpitaton l"— __________;E-‘—'-I.*I I I I I 20--.;...............E E 5 5 .... .................................. :------------------------------ 5”".T "";._l——~.I I I I J :_;~' O _. 10-mn E E 0'1 35 15-mn 30-mn 60-mn 2-hr 3-hr 6-hr 12-hr Duration 24-hr 2-day 3-day 4-day 7-day 10-day 20-day 30-day 45-day 60-day depth(nl p-‘taton [EC 10 I I .___i-_...__--'.'_..—-'...._,_-—-'. i ._.... .--"'.I ._-~*_-—___.-’.,..-—- P ._-...___-|—.____._........\......................;_L,-<...|.........._?_......_-—_.-——"__ 5 ..‘______,.-___:>_____._._; 5 __;_",_.T--5--:____—fi_jTTi‘__-—_'_‘_‘§'__.._-—-5*"I +_---5 - -1-"1—+—i-—0 '_F 1 2 5 10 25 50 100 200 Average recurrence interval lyear5l NQAA A335 14_Vglumg 9,Vefgign 3 Created (GMT):Thu jun 24 20:27:57 2021 Back to Top Maps &aerials Small scale terrain 500 1000 (years) _......_........_...........:...._.:......:._._._....:....'.II,-‘Ir i 1 2 5 10 25 50 100 200 500 1000 __.._...._....._...._._.._..1 ........._...._..._...._._._...._1 _........_.........Duration 20-....._............................................‘5-min 1 0—m|n 1 5-min 30-mm 60-min 2-hr 3-hr 6-hr 12-hr 24-hr 2-day 3-day 4-day 7-day 10-day 20-day 30-day 45-day 60-day Large scale map-_.~*__"\I,-_ .;II 1;; ‘I -\'._1"IF I Im|F_',I ...'':1-I ._,1- ‘-.|I1:-_-.n ______;I_IIq —:1 .__ -»=>1;I;I.;... .i>*I,»._~.:+--'--'._-.'§~.__‘.q .-'---'._-1»--__.-.-I '.'1.-..-.._1,-__fi_)A 5 ‘ ',.-ij9r'1*,-3%"_1 ‘grip _-fl.—»II_I_in '~- '“-._—-__ L€;@i§F¥-I 1.5 -."(._.1 _t_)"K.‘I §1,'.*\_...- rI I '.II "'‘9 8 ~:|1-100km .4’"-.llie)-1 6_60mi ._ H - Large scale aerial Back to Top US Department of Commerce National Oceanic and Atmospheric Administration National Weather Service National Water Center 1325 East West Highway Silver Spring,MD 20910 Questions?:HDSC.Questions@noaa.gg Disclaimer APPENDIX – C PRE-DEVELOPMENT RUNOFF CALCULATIONS Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Hyd.Origin Description 1 Rational Area - A 2 Rational Area - B 3 Rational Area - C 4 Rational Area - D 5 Rational Area - E 6 Reservoir Underground Detention 7 Combine Outfall - A & C 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 Rational -------------0.869 -------1.035 1.169 1.341 --------------Area - A 2 Rational -------------0.614 -------0.732 0.826 0.948 --------------Area - B 3 Rational -------------0.180 -------0.214 0.242 0.277 --------------Area - C 4 Rational -------------0.820 -------0.973 1.097 1.261 --------------Area - D 5 Rational -------------1.085 -------1.287 1.452 1.669 --------------Area - E 6 Reservoir 3 -------0.174 -------0.208 0.235 0.270 --------------Underground Detention 7 Combine 1, 6 -------1.042 -------1.243 1.403 1.611 --------------Outfall - A & C Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.120 x 0.35) + (0.100 x 0.95)] / 0.220 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.100 x 0.95) + (0.120 x 0.35)] / 0.190 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Storage Indication method used. Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 UG Chambers -Invert elev. = 289.20 ft, Rise x Span = 2.50 x 2.50 ft, Barrel Len = 164.00 ft, No. Barrels = 1, Slope = 0.50%, Headers = No Stage (ft)Elevation (ft)Contour area (sqft)Incr. Storage (cuft)Total storage (cuft) 0.00 289.20 n/a 0 0 0.33 289.53 n/a 11 11 0.66 289.86 n/a 47 57 1.00 290.20 n/a 93 150 1.33 290.53 n/a 121 271 1.66 290.86 n/a 132 403 1.99 291.19 n/a 132 535 2.32 291.52 n/a 121 655 2.66 291.86 n/a 93 748 2.99 292.19 n/a 47 795 3.32 292.52 n/a 11 805 Rise (in)= 8.00 0.00 0.00 0.00 Span (in)= 8.00 0.00 0.00 0.00 No. Barrels = 1 0 0 0 Invert El. (ft)= 289.20 0.00 0.00 0.00 Length (ft)= 57.00 0.00 0.00 0.00 Slope (%)= 4.00 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a No No No Crest Len (ft)= 0.00 0.00 0.00 0.00 Crest El. (ft)= 0.00 0.00 0.00 0.00 Weir Coeff.= 3.33 3.33 3.33 3.33 Weir Type = ------------ Multi-Stage = No No No No Exfil.(in/hr)= 0.000 (by Wet area) TW Elev. (ft)= 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). Stage Storage Elevation Clv A Clv B Clv C PrfRsr Wr A Wr B Wr C Wr D Exfil User Total ft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs 0.00 0 289.20 0.00 ---------------------------0.000 0.03 1 289.23 0.00 ic ---------------------------0.004 0.07 2 289.27 0.02 ic ---------------------------0.016 0.10 3 289.30 0.04 ic ---------------------------0.035 0.13 4 289.33 0.06 ic ---------------------------0.062 0.17 5 289.37 0.09 ic ---------------------------0.094 0.20 6 289.40 0.13 ic ---------------------------0.133 0.23 7 289.43 0.18 ic ---------------------------0.178 0.27 8 289.47 0.23 ic ---------------------------0.228 0.30 10 289.50 0.28 ic ---------------------------0.282 0.33 11 289.53 0.34 ic ---------------------------0.341 0.37 15 289.57 0.40 ic ---------------------------0.403 0.40 20 289.60 0.47 ic ---------------------------0.468 0.43 25 289.63 0.54 ic ---------------------------0.535 0.46 29 289.66 0.60 ic ---------------------------0.604 0.50 34 289.70 0.67 ic ---------------------------0.672 0.53 39 289.73 0.74 ic ---------------------------0.740 0.56 43 289.76 0.81 ic ---------------------------0.806 0.60 48 289.80 0.87 ic ---------------------------0.868 0.63 53 289.83 0.92 ic ---------------------------0.924 0.66 57 289.86 0.97 ic ---------------------------0.968 0.70 66 289.90 1.01 ic ---------------------------1.014 0.73 76 289.93 1.06 ic ---------------------------1.059 0.76 85 289.96 1.10 ic ---------------------------1.102 0.80 94 290.00 1.14 ic ---------------------------1.144 0.83 104 290.03 1.18 ic ---------------------------1.184 0.86 113 290.06 1.22 ic ---------------------------1.223 0.90 122 290.10 1.26 ic ---------------------------1.261 0.93 131 290.13 1.30 ic ---------------------------1.298 0.96 141 290.16 1.33 ic ---------------------------1.333 1.00 150 290.20 1.37 ic ---------------------------1.368 1.03 162 290.23 1.40 ic ---------------------------1.402 Continues on next page... Existing Underground Detention Stage Storage Elevation Clv A Clv B Clv C PrfRsr Wr A Wr B Wr C Wr D Exfil User Total ft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs 1.06 174 290.26 1.43 ic ---------------------------1.435 1.10 186 290.30 1.47 ic ---------------------------1.467 1.13 198 290.33 1.50 ic ---------------------------1.499 1.16 210 290.36 1.53 ic ---------------------------1.530 1.20 222 290.40 1.56 ic ---------------------------1.560 1.23 234 290.43 1.59 ic ---------------------------1.590 1.26 247 290.46 1.62 ic ---------------------------1.619 1.29 259 290.49 1.65 ic ---------------------------1.648 1.33 271 290.53 1.68 ic ---------------------------1.676 1.36 284 290.56 1.70 ic ---------------------------1.704 1.39 297 290.59 1.73 ic ---------------------------1.731 1.43 310 290.63 1.76 ic ---------------------------1.758 1.46 324 290.66 1.78 ic ---------------------------1.784 1.49 337 290.69 1.81 ic ---------------------------1.811 1.53 350 290.73 1.84 ic ---------------------------1.836 1.56 363 290.76 1.86 ic ---------------------------1.862 1.59 376 290.79 1.89 ic ---------------------------1.887 1.63 390 290.83 1.91 ic ---------------------------1.911 1.66 403 290.86 1.94 ic ---------------------------1.936 1.69 416 290.89 1.96 ic ---------------------------1.960 1.73 429 290.93 1.98 ic ---------------------------1.984 1.76 442 290.96 2.01 ic ---------------------------2.007 1.79 455 290.99 2.03 ic ---------------------------2.030 1.83 469 291.03 2.05 ic ---------------------------2.053 1.86 482 291.06 2.08 ic ---------------------------2.076 1.89 495 291.09 2.10 ic ---------------------------2.098 1.93 508 291.13 2.12 ic ---------------------------2.121 1.96 521 291.16 2.14 ic ---------------------------2.143 1.99 535 291.19 2.16 ic ---------------------------2.164 2.03 547 291.23 2.19 ic ---------------------------2.186 2.06 559 291.26 2.21 ic ---------------------------2.207 2.09 571 291.29 2.23 ic ---------------------------2.228 2.12 583 291.32 2.25 ic ---------------------------2.249 2.16 595 291.36 2.27 ic ---------------------------2.270 2.19 607 291.39 2.29 ic ---------------------------2.291 2.22 619 291.42 2.31 ic ---------------------------2.311 2.26 631 291.46 2.33 ic ---------------------------2.331 2.29 643 291.49 2.35 ic ---------------------------2.351 2.32 655 291.52 2.37 ic ---------------------------2.371 2.36 665 291.56 2.39 ic ---------------------------2.391 2.39 674 291.59 2.41 ic ---------------------------2.410 2.42 683 291.62 2.43 ic ---------------------------2.430 2.46 692 291.66 2.45 ic ---------------------------2.449 2.49 702 291.69 2.47 ic ---------------------------2.468 2.52 711 291.72 2.49 ic ---------------------------2.487 2.56 720 291.76 2.51 ic ---------------------------2.506 2.59 730 291.79 2.52 ic ---------------------------2.524 2.62 739 291.82 2.54 ic ---------------------------2.543 2.66 748 291.86 2.56 ic ---------------------------2.561 2.69 753 291.89 2.58 ic ---------------------------2.579 2.72 757 291.92 2.60 ic ---------------------------2.598 2.76 762 291.96 2.62 ic ---------------------------2.616 2.79 767 291.99 2.63 ic ---------------------------2.633 2.82 771 292.02 2.65 ic ---------------------------2.651 2.86 776 292.06 2.67 ic ---------------------------2.669 2.89 781 292.09 2.69 ic ---------------------------2.686 2.92 785 292.12 2.70 ic ---------------------------2.704 2.95 790 292.15 2.72 ic ---------------------------2.721 2.99 795 292.19 2.74 ic ---------------------------2.738 3.02 796 292.22 2.76 ic ---------------------------2.755 3.05 797 292.25 2.77 ic ---------------------------2.772 3.09 798 292.29 2.79 ic ---------------------------2.789 3.12 799 292.32 2.81 ic ---------------------------2.806 3.15 800 292.35 2.82 ic ---------------------------2.822 3.19 801 292.39 2.84 ic ---------------------------2.839 3.22 802 292.42 2.86 ic ---------------------------2.855 3.25 803 292.45 2.87 ic ---------------------------2.872 3.29 804 292.49 2.89 ic ---------------------------2.888 3.32 805 292.52 2.90 ic ---------------------------2.904 ...End Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.120 x 0.35) + (0.100 x 0.95)] / 0.220 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.100 x 0.95) + (0.120 x 0.35)] / 0.190 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Storage Indication method used. Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.120 x 0.35) + (0.100 x 0.95)] / 0.220 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.100 x 0.95) + (0.120 x 0.35)] / 0.190 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Storage Indication method used. Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.120 x 0.35) + (0.100 x 0.95)] / 0.220 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.100 x 0.95) + (0.120 x 0.35)] / 0.190 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Storage Indication method used. Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Return Intensity-Duration-Frequency Equation Coefficients (FHA) Period (Yrs)B D E (N/A) 1 0.0000 0.0000 0.0000 -------- 2 27.7780 5.3000 0.6561 -------- 3 0.0000 0.0000 0.0000 -------- 5 35.2307 5.8000 0.6713 -------- 10 40.2792 5.9000 0.6744 -------- 25 44.2761 5.6000 0.6634 -------- 50 47.5888 5.4000 0.6588 -------- 100 49.4311 5.2000 0.6479 -------- File name: IDF_Little Rock.IDF Return Intensity Values (in/hr) Period (Yrs)5 min 10 15 20 25 30 35 40 45 50 55 60 1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2 6.01 4.64 3.85 3.33 2.96 2.68 2.46 2.28 2.12 2.00 1.89 1.79 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 7.13 5.52 4.59 3.97 3.53 3.19 2.92 2.70 2.52 2.37 2.24 2.12 10 8.04 6.24 5.19 4.49 3.98 3.60 3.30 3.05 2.84 2.67 2.52 2.39 25 9.25 7.16 5.95 5.15 4.58 4.14 3.79 3.51 3.28 3.08 2.91 2.76 50 10.17 7.86 6.53 5.65 5.02 4.54 4.16 3.85 3.60 3.38 3.19 3.03 100 10.98 8.48 7.05 6.11 5.43 4.92 4.51 4.18 3.91 3.68 3.48 3.30 Tc = time in minutes. Values may exceed 60. Precip. file name: C:\Dropbox (Ozark Civil)\Michael\Storm Frequency\SCS_Little Rock, Pulaski Co. AR.pcp Storm Distribution 1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr SCS 24-hour 3.71 4.26 0.00 5.24 6.11 7.38 8.44 9.55 SCS 6-Hr 2.67 3.03 0.00 3.63 4.14 4.87 5.46 6.06 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 Pre-development.gpw Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 APPENDIX – D POST-DEVELOPMENT RUNOFF CALCULATIONS & OUTFALL STRUCTURE DETAIL Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Hyd.Origin Description 1 Rational Area - A 2 Rational Area - B 3 Mod. Rational Area - C 4 Rational Area - D 5 Rational Area - E 6 Reservoir Underground Detention 7 Combine Outfall - A & C Post-development.gpw Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 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 Rational -------------0.610 -------0.724 0.816 0.939 --------------Area - A 2 Rational -------------0.253 -------0.300 0.338 0.388 --------------Area - B 3 Mod. Rational -------------4.027 -------4.775 5.386 6.192 --------------Area - C 4 Rational -------------0.782 -------0.927 1.046 1.202 --------------Area - D 5 Rational -------------1.085 -------1.287 1.452 1.669 --------------Area - E 6 Reservoir 3 -------0.444 -------0.475 0.499 0.609 --------------Underground Detention 7 Combine 1, 6 -------0.971 -------1.106 1.215 1.357 --------------Outfall - A & C Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.020 x 0.35) + (0.700 x 0.95)] / 0.720 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.100 x 0.35) + (0.100 x 0.95)] / 0.200 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Storage Indication method used. Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 UG Chambers -Invert elev. = 289.20 ft, Rise x Span = 2.50 x 2.50 ft, Barrel Len = 164.00 ft, No. Barrels = 3, Slope = 0.50%, Headers = No Stage (ft)Elevation (ft)Contour area (sqft)Incr. Storage (cuft)Total storage (cuft) 0.00 289.20 n/a 0 0 0.33 289.53 n/a 32 32 0.66 289.86 n/a 140 172 1.00 290.20 n/a 278 450 1.33 290.53 n/a 362 812 1.66 290.86 n/a 396 1,208 1.99 291.19 n/a 396 1,604 2.32 291.52 n/a 362 1,966 2.66 291.86 n/a 278 2,244 2.99 292.19 n/a 140 2,384 3.32 292.52 n/a 32 2,416 Rise (in)= 8.00 4.00 0.00 0.00 Span (in)= 8.00 4.00 0.00 0.00 No. Barrels = 1 1 0 0 Invert El. (ft)= 289.20 289.20 0.00 0.00 Length (ft)= 57.00 0.00 0.00 0.00 Slope (%)= 4.00 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff.= 0.60 0.60 0.60 0.60 Multi-Stage = n/a Yes No No Crest Len (ft)= 42.00 10.50 0.00 0.00 Crest El. (ft)= 293.90 291.20 0.00 0.00 Weir Coeff.= 3.33 3.33 3.33 3.33 Weir Type = 1 Rect ------ Multi-Stage = Yes Yes No No Exfil.(in/hr)= 0.000 (by Wet area) TW Elev. (ft)= 0.00 Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). Stage Storage Elevation Clv A Clv B Clv C PrfRsr Wr A Wr B Wr C Wr D Exfil User Total ft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs 0.00 0 289.20 0.00 0.00 ------0.00 0.00 ------------0.000 0.03 3 289.23 0.00 ic 0.00 ic ------0.00 0.00 ------------0.002 0.07 6 289.27 0.01 ic 0.01 ic ------0.00 0.00 ------------0.008 0.10 10 289.30 0.02 ic 0.02 ic ------0.00 0.00 ------------0.018 0.13 13 289.33 0.03 ic 0.03 ic ------0.00 0.00 ------------0.031 0.17 16 289.37 0.05 ic 0.05 ic ------0.00 0.00 ------------0.047 0.20 19 289.40 0.07 ic 0.07 ic ------0.00 0.00 ------------0.066 0.23 22 289.43 0.09 ic 0.09 ic ------0.00 0.00 ------------0.086 0.27 25 289.47 0.11 ic 0.11 ic ------0.00 0.00 ------------0.107 0.30 29 289.50 0.13 ic 0.13 ic ------0.00 0.00 ------------0.129 0.33 32 289.53 0.15 ic 0.15 ic ------0.00 0.00 ------------0.147 0.37 46 289.57 0.16 ic 0.16 ic ------0.00 0.00 ------------0.161 0.40 60 289.60 0.17 ic 0.17 ic ------0.00 0.00 ------------0.174 0.43 74 289.63 0.19 ic 0.19 ic ------0.00 0.00 ------------0.186 0.46 88 289.66 0.20 ic 0.20 ic ------0.00 0.00 ------------0.197 0.50 102 289.70 0.21 ic 0.21 ic ------0.00 0.00 ------------0.209 0.53 116 289.73 0.22 ic 0.22 ic ------0.00 0.00 ------------0.219 0.56 130 289.76 0.23 ic 0.23 ic ------0.00 0.00 ------------0.230 0.60 144 289.80 0.24 ic 0.24 ic ------0.00 0.00 ------------0.240 0.63 158 289.83 0.25 ic 0.25 ic ------0.00 0.00 ------------0.250 0.66 172 289.86 0.26 ic 0.26 ic ------0.00 0.00 ------------0.259 0.70 199 289.90 0.27 ic 0.27 ic ------0.00 0.00 ------------0.268 0.73 227 289.93 0.28 ic 0.28 ic ------0.00 0.00 ------------0.277 0.76 255 289.96 0.29 ic 0.29 ic ------0.00 0.00 ------------0.286 0.80 283 290.00 0.29 ic 0.29 ic ------0.00 0.00 ------------0.295 0.83 311 290.03 0.30 ic 0.30 ic ------0.00 0.00 ------------0.303 0.86 339 290.06 0.31 ic 0.31 ic ------0.00 0.00 ------------0.312 0.90 366 290.10 0.32 ic 0.32 ic ------0.00 0.00 ------------0.320 0.93 394 290.13 0.33 ic 0.33 ic ------0.00 0.00 ------------0.327 0.96 422 290.16 0.34 ic 0.33 ic ------0.00 0.00 ------------0.335 1.00 450 290.20 0.34 ic 0.34 ic ------0.00 0.00 ------------0.342 1.03 486 290.23 0.35 ic 0.35 ic ------0.00 0.00 ------------0.350 Continues on next page... Existing Underground Detention Stage Storage Elevation Clv A Clv B Clv C PrfRsr Wr A Wr B Wr C Wr D Exfil User Total ft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs 1.06 522 290.26 0.36 ic 0.36 ic ------0.00 0.00 ------------0.357 1.10 559 290.30 0.37 ic 0.36 ic ------0.00 0.00 ------------0.364 1.13 595 290.33 0.37 ic 0.37 ic ------0.00 0.00 ------------0.371 1.16 631 290.36 0.38 ic 0.38 ic ------0.00 0.00 ------------0.379 1.20 667 290.40 0.39 ic 0.39 ic ------0.00 0.00 ------------0.385 1.23 703 290.43 0.39 ic 0.39 ic ------0.00 0.00 ------------0.392 1.26 740 290.46 0.40 ic 0.40 ic ------0.00 0.00 ------------0.399 1.29 776 290.49 0.41 ic 0.41 ic ------0.00 0.00 ------------0.405 1.33 812 290.53 0.41 ic 0.41 ic ------0.00 0.00 ------------0.411 1.36 852 290.56 0.42 ic 0.42 ic ------0.00 0.00 ------------0.418 1.39 891 290.59 0.43 ic 0.42 ic ------0.00 0.00 ------------0.424 1.43 931 290.63 0.43 ic 0.43 ic ------0.00 0.00 ------------0.430 1.46 971 290.66 0.44 ic 0.44 ic ------0.00 0.00 ------------0.437 1.49 1,010 290.69 0.45 ic 0.44 ic ------0.00 0.00 ------------0.442 1.53 1,050 290.73 0.45 ic 0.45 ic ------0.00 0.00 ------------0.449 1.56 1,089 290.76 0.46 ic 0.45 ic ------0.00 0.00 ------------0.454 1.59 1,129 290.79 0.46 ic 0.46 ic ------0.00 0.00 ------------0.460 1.63 1,169 290.83 0.47 ic 0.47 ic ------0.00 0.00 ------------0.466 1.66 1,208 290.86 0.47 ic 0.47 ic ------0.00 0.00 ------------0.472 1.69 1,248 290.89 0.48 ic 0.48 ic ------0.00 0.00 ------------0.478 1.73 1,287 290.93 0.48 ic 0.48 ic ------0.00 0.00 ------------0.483 1.76 1,327 290.96 0.49 ic 0.49 ic ------0.00 0.00 ------------0.489 1.79 1,366 290.99 0.50 ic 0.49 ic ------0.00 0.00 ------------0.494 1.83 1,406 291.03 0.50 ic 0.50 ic ------0.00 0.00 ------------0.500 1.86 1,446 291.06 0.51 ic 0.50 ic ------0.00 0.00 ------------0.505 1.89 1,485 291.09 0.51 ic 0.51 ic ------0.00 0.00 ------------0.510 1.93 1,525 291.13 0.52 ic 0.52 ic ------0.00 0.00 ------------0.515 1.96 1,564 291.16 0.52 ic 0.52 ic ------0.00 0.00 ------------0.521 1.99 1,604 291.19 0.53 ic 0.53 ic ------0.00 0.00 ------------0.526 2.03 1,640 291.23 0.66 ic 0.52 ic ------0.00 0.14 ------------0.660 2.06 1,676 291.26 0.99 ic 0.49 ic ------0.00 0.49 ------------0.987 2.09 1,713 291.29 1.40 ic 0.43 ic ------0.00 0.97 ------------1.402 2.12 1,749 291.32 1.86 ic 0.32 ic ------0.00 1.54 ------------1.858 2.16 1,785 291.36 2.20 ic 0.14 ic ------0.00 2.06 s ------------2.199 2.19 1,821 291.39 2.25 ic 0.11 ic ------0.00 2.15 s ------------2.251 2.22 1,858 291.42 2.29 ic 0.08 ic ------0.00 2.20 s ------------2.286 2.26 1,894 291.46 2.31 ic 0.07 ic ------0.00 2.24 s ------------2.312 2.29 1,930 291.49 2.34 ic 0.06 ic ------0.00 2.28 s ------------2.337 2.32 1,966 291.52 2.36 ic 0.05 ic ------0.00 2.30 s ------------2.357 2.36 1,994 291.56 2.38 ic 0.05 ic ------0.00 2.33 s ------------2.379 2.39 2,022 291.59 2.40 ic 0.04 ic ------0.00 2.36 s ------------2.402 2.42 2,050 291.62 2.43 ic 0.04 ic ------0.00 2.38 s ------------2.419 2.46 2,077 291.66 2.45 ic 0.03 ic ------0.00 2.41 s ------------2.444 2.49 2,105 291.69 2.47 ic 0.03 ic ------0.00 2.42 s ------------2.451 2.52 2,133 291.72 2.48 ic 0.03 ic ------0.00 2.44 s ------------2.469 2.56 2,161 291.76 2.50 ic 0.03 ic ------0.00 2.47 s ------------2.497 2.59 2,189 291.79 2.52 ic 0.02 ic ------0.00 2.50 s ------------2.521 2.62 2,216 291.82 2.54 ic 0.02 ic ------0.00 2.49 s ------------2.516 2.66 2,244 291.86 2.56 ic 0.02 ic ------0.00 2.52 s ------------2.539 2.69 2,258 291.89 2.58 ic 0.02 ic ------0.00 2.54 s ------------2.556 2.72 2,272 291.92 2.60 ic 0.02 ic ------0.00 2.58 s ------------2.596 2.76 2,286 291.96 2.61 ic 0.02 ic ------0.00 2.55 s ------------2.567 2.79 2,300 291.99 2.63 ic 0.02 ic ------0.00 2.55 s ------------2.568 2.82 2,314 292.02 2.65 ic 0.02 ic ------0.00 2.61 s ------------2.626 2.86 2,328 292.06 2.67 ic 0.01 ic ------0.00 2.58 s ------------2.596 2.89 2,342 292.09 2.69 ic 0.01 ic ------0.00 2.61 s ------------2.625 2.92 2,356 292.12 2.70 ic 0.01 ic ------0.00 2.64 s ------------2.650 2.95 2,370 292.15 2.72 ic 0.01 ic ------0.00 2.62 s ------------2.631 2.99 2,384 292.19 2.74 ic 0.01 ic ------0.00 2.61 s ------------2.621 3.02 2,387 292.22 2.75 ic 0.01 ic ------0.00 2.72 s ------------2.736 3.05 2,390 292.25 2.77 ic 0.01 ic ------0.00 2.71 s ------------2.717 3.09 2,393 292.29 2.79 ic 0.01 ic ------0.00 2.67 s ------------2.682 3.12 2,397 292.32 2.81 ic 0.01 ic ------0.00 2.77 s ------------2.783 3.15 2,400 292.35 2.82 ic 0.01 ic ------0.00 2.71 s ------------2.725 3.19 2,403 292.39 2.84 ic 0.01 ic ------0.00 2.83 s ------------2.837 3.22 2,406 292.42 2.86 ic 0.01 ic ------0.00 2.74 s ------------2.752 3.25 2,409 292.45 2.87 ic 0.01 ic ------0.00 2.84 s ------------2.850 3.29 2,412 292.49 2.89 ic 0.01 ic ------0.00 2.65 s ------------2.654 3.32 2,416 292.52 2.90 ic 0.01 ic ------0.00 2.76 s ------------2.766 ...End Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.020 x 0.35) + (0.700 x 0.95)] / 0.720 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.100 x 0.35) + (0.100 x 0.95)] / 0.200 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Storage Indication method used. Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.020 x 0.35) + (0.700 x 0.95)] / 0.720 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.100 x 0.35) + (0.100 x 0.95)] / 0.200 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Storage Indication method used. Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.020 x 0.35) + (0.700 x 0.95)] / 0.720 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 * Composite (Area/C) = [(0.100 x 0.35) + (0.100 x 0.95)] / 0.200 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Storage Indication method used. Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2019 Friday, 07 / 9 / 2021 Return Intensity-Duration-Frequency Equation Coefficients (FHA) Period (Yrs)B D E (N/A) 1 0.0000 0.0000 0.0000 -------- 2 27.7780 5.3000 0.6561 -------- 3 0.0000 0.0000 0.0000 -------- 5 35.2307 5.8000 0.6713 -------- 10 40.2792 5.9000 0.6744 -------- 25 44.2761 5.6000 0.6634 -------- 50 47.5888 5.4000 0.6588 -------- 100 49.4311 5.2000 0.6479 -------- File name: IDF_Little Rock.IDF Return Intensity Values (in/hr) Period (Yrs)5 min 10 15 20 25 30 35 40 45 50 55 60 1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 2 6.01 4.64 3.85 3.33 2.96 2.68 2.46 2.28 2.12 2.00 1.89 1.79 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 7.13 5.52 4.59 3.97 3.53 3.19 2.92 2.70 2.52 2.37 2.24 2.12 10 8.04 6.24 5.19 4.49 3.98 3.60 3.30 3.05 2.84 2.67 2.52 2.39 25 9.25 7.16 5.95 5.15 4.58 4.14 3.79 3.51 3.28 3.08 2.91 2.76 50 10.17 7.86 6.53 5.65 5.02 4.54 4.16 3.85 3.60 3.38 3.19 3.03 100 10.98 8.48 7.05 6.11 5.43 4.92 4.51 4.18 3.91 3.68 3.48 3.30 Tc = time in minutes. Values may exceed 60. Precip. file name: C:\Dropbox (Ozark Civil)\Michael\Storm Frequency\SCS_Little Rock, Pulaski Co. AR.pcp Storm Distribution 1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr SCS 24-hour 3.71 4.26 0.00 5.24 6.11 7.38 8.44 9.55 SCS 6-Hr 2.67 3.03 0.00 3.63 4.14 4.87 5.46 6.06 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 APPENDIX-E POST-DEVELOPMENT PIPE/INLET CALCULATIONS 10-YEAR STORM 25-YEAR STORM