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HomeMy WebLinkAbout2019 08 02 - CBA Carmel Stormwater Drainage Technical Report Stormwater Management Plan For: CHRISTIAN BROTHERS AUTOMOTIVE SERVICE CENTER Prepared for: Christian Brothers Automotive Corporation Jonathan Wakefield 17725 Katy Freeway | Suite 200 Houston, TX 77094 Prepared by: Progressive Architecture Engineering, P.C. 1811 4 Mile Road NE Grand Rapids, MI 49525-2442 616/361-2664 August 2, 2019 Project No: 70050012 TABLE OF CONTENTS INTRODUCTION ........................................................................................................................................... 1 EXISTING CONDITIONS .............................................................................................................................. 1 PROPOSED DEVELOPMENT...................................................................................................................... 1 Design Standards ..................................................................................................................................... 1 Proposed Storm Pipe Network ................................................................................................................. 1 Water Quality ........................................................................................................................................... 1 Detention ................................................................................................................................................. 1 APPENDICIES Appendix 1 Existing Conditions Drainage Area Map Appendix 2 Post-Development Drainage Area Map – Pipe Network Sizing Appendix 3 Post-Development Drainage Area Map – Detention Sizing Appendix 4 Stormwater Design Calculations STORMWATER MANAGEMENT PLAN Christian Brothers Automotive Service Center 70050012 Stormwater Management Plan Page 1 INTRODUCTION Christian Brothers Automotive Service center is the first project as part of the overall development, “Michigan Road Retail Site Development.” The 5,660 square foot automotive service building is proposed on a 1.23-acre parcel with proposed parking, dumpster enclosure and landscaping. In 2018, plans were approved for a multi-family housing development, “Aria.” As part of this development, a large detention basin and water quality units were sized to accommodate both the Aria Development as well as the parcel to the east, Michigan Road Retail Site Development, which the Christian Brothers property is part of. EXISTING CONDITIONS The existing parcel is an open field with fallow ground cover. The east quarter of the property drains to a low point on the east side and the rest of the site drains to the west where it collects and pools in low areas. The existing soil is silty clay and loam with poor infiltration. Appendix 1 shows a drainage area map of existing conditions. PROPOSED DEVELOPMENT Design Standards The proposed stormwater management plan is designed in accordance with “The City of Carmel Stormwater Technical Standards Manual.” Proposed Storm Pipe Network The proposed Christian Brothers stormwater pipe network is designed to handle the stormwater discharge of a 10-year storm event and provide 2-1/2 feet minimum cover at all catch basins. The storm runoff will be collected in catch basins around the site and discharge to a catch basin in Redd Road, proposed as part of the Redd Road extension. The building roof runoff will collect in underdrains and connect to catch basins at the front and rear of the building. The landscaped area behind the building and on the east side of the building will be graded to provided adequate drainage to several yard drains. Appendix 2 shows a drainage area map to each catch basin for pipe network sizing and includes off site drainage. Water Quality Water quality for the proposed Christian Brothers site will be treated off-site on the Aria Development. Water quality will be provided with 3 mechanical water quality units sized to serve both the multi-family development and the Michigan Road Retail Site Development, which includes the Christian Brothers site. Please refer to the “Stormwater Technical Report for Michigan Road Site” which was approved for the Aria Development and Michigan Road Retail Development for more details on the water quality units. Detention Basins Stormwater detention and restricted release will be provided by a large detention basin on the Aria Development site. This detention basin will store water for the multi-family development and the Michigan Road Retail Site Development, which includes the Christian Brothers site. Appendix 3 shows a drainage area map used for detention sizing calculations. The runoff curve number for the proposed Christian Brothers site is 91 and the detention sizing calculations assumed a runoff curve number of 92.8 for this commercial development. Please refer to the “Stormwater Technical Report for Michigan Road Site” which was approved for the Aria Development and Michigan Road Retail Development for more details on the detention sizing and release rates. STORMWATER MANAGEMENT PLAN Christian Brothers Automotive Service Center 70050012 Stormwater Management Plan APPENDIX 1 Existing Conditions Drainage Area Map X X O H E 90 0 900 9 0 0 9 0 1 9 0 1 90 1 90 0 89 9 900 899 901 898 898 1"= DRAINAGE AREA MAP - EXISTING CONDITIONS 40'040' ISSUANCES DRAWN BY PROFESSIONAL PROJECT MANAGER FILE NUMBER CHECKED BY 18 1 1 4 M i l e R d N E G r a n d R a p i d s , M I 4 9 5 2 5 6 1 6 . 3 6 1 . 2 6 6 4 w w w . p r o g r e s s i v e a e . c o m TH I S D O C U M E N T H A S B E E N P R E P A R E D B Y P R O G R E S S I V E A E A S A N I N S T R U M E N T O F S E R V I C E , A N D P R O G R E S S I V E A E SH A L L R E T A I N A L L C O M M O N L A W , S T A T U T O R Y A N D O T H E R R E S E R V E D R I G H T S , I N C L U D I N G T H E C O P Y R I G H T T H E R E T O . 7/ 3 1 / 2 0 1 9 2 : 5 5 : 3 6 P M P: \ 7 0 0 5 0 0 1 2 \ W I P D R A W I N G S \ D r a i n a g e A r e a M a p . d w g sh o r t j CH R I S T I A N B R O T H E R S A U T O M O T I V E PR O P O S E D S E R V I C E CE N T E R CA R M E L , I N D I A N A 70050012 JPM JPM JRS DRAINAGE AREA MAP - EXISTING CONDITIONS DRAINAGE AREA PERVIOUS AREA IMPERVIOUS AREA RUNOFF CURVE NUMBER TOTAL PROPERTY AREA 1.23 Ac 1.23 Ac 0.00 Ac 90 PERVIOUS AREA IS FALLOW CROP RESIDUE (CR) IN GOOD CONDITION - HYDROLOGIC SOIL GROUP D -EXISTING FALLOW LAND STORMWATER MANAGEMENT PLAN Christian Brothers Automotive Service Center 70050012 Stormwater Management Plan APPENDIX 2 Post-Development Drainage Area Map – Pipe Network Sizing W CB-1 CB-2 CB-3 YD-3A YD-3B YD-3C CB-5 CB-4 CO CO CO CO CO 90 0 900 9 0 0 9 0 1 9 0 1 90 1 90 0 89 9 900 899 901 898 898 900 901 9 0 0 900 901 900 900901 901 YD-5A 1"= DRAINAGE AREA MAP - PIPE NETWORK SIZING 40'040' ISSUANCES DRAWN BY PROFESSIONAL PROJECT MANAGER FILE NUMBER CHECKED BY 18 1 1 4 M i l e R d N E G r a n d R a p i d s , M I 4 9 5 2 5 6 1 6 . 3 6 1 . 2 6 6 4 w w w . p r o g r e s s i v e a e . c o m TH I S D O C U M E N T H A S B E E N P R E P A R E D B Y P R O G R E S S I V E A E A S A N I N S T R U M E N T O F S E R V I C E , A N D P R O G R E S S I V E A E SH A L L R E T A I N A L L C O M M O N L A W , S T A T U T O R Y A N D O T H E R R E S E R V E D R I G H T S , I N C L U D I N G T H E C O P Y R I G H T T H E R E T O . 7/ 3 1 / 2 0 1 9 2 : 5 5 : 2 5 P M P: \ 7 0 0 5 0 0 1 2 \ W I P D R A W I N G S \ D r a i n a g e A r e a M a p . d w g sh o r t j CH R I S T I A N B R O T H E R S A U T O M O T I V E PR O P O S E D S E R V I C E CE N T E R CA R M E L , I N D I A N A 70050012 JPM JPM JRS CATCH BASIN DRAINAGE AREA PERVIOUS AREA IMPERVIOUS AREA CB-1 0.08 Ac 0.03 Ac 0.05 Ac CB-2 0.01 Ac 0.01 Ac 0.00 Ac CB-3 0.05 Ac 0.00 Ac 0.05 Ac CB-4 0.17 Ac 0.03 Ac 0.14 Ac CB-5 0.28 Ac 0.02 Ac 0.26 Ac YD-3A 0.34 Ac (0.25 Ac off-site) 0.33 Ac 0.01 Ac YD-3B 0.23 Ac (0.14 Ac off-site)0.19 Ac 0.04 Ac YD-3C 0.20 Ac (0.01 Ac off-site)0.18 Ac 0.02 Ac YD-5A 0.29 Ac (0.24 Ac off-site)0.28 Ac 0.01 Ac DRAINAGE AREA TO CBA CATCH BASINS 1.65 Ac 1.07 Ac 0.58 Ac Total Off-site drainage area to CBA catch basins = 0.64 Acres DRAINAGE AREA MAP - PIPE NETWORK SIZING -ON-SITE DRAINAGE AREA -OFF-SITE DRAINAGE AREA -PERVIOUS AREA STORMWATER MANAGEMENT PLAN Christian Brothers Automotive Service Center 70050012 Stormwater Management Plan APPENDIX 3 Post-Development Drainage Area Map – Detention Sizing X X CB-1 CB-2 CB-3 YD-3A YD-3B YD-3C CB-5 CB-4 CO CO CO CO CO 90 0 900 9 0 0 9 0 1 9 0 1 90 1 90 0 89 9 900 899 901 898 898 YD-5A 1"= DRAINAGE AREA MAP - DETENTION SIZING 40'040' -PERVIOUS AREA ISSUANCES DRAWN BY PROFESSIONAL PROJECT MANAGER FILE NUMBER CHECKED BY 18 1 1 4 M i l e R d N E G r a n d R a p i d s , M I 4 9 5 2 5 6 1 6 . 3 6 1 . 2 6 6 4 w w w . p r o g r e s s i v e a e . c o m TH I S D O C U M E N T H A S B E E N P R E P A R E D B Y P R O G R E S S I V E A E A S A N I N S T R U M E N T O F S E R V I C E , A N D P R O G R E S S I V E A E SH A L L R E T A I N A L L C O M M O N L A W , S T A T U T O R Y A N D O T H E R R E S E R V E D R I G H T S , I N C L U D I N G T H E C O P Y R I G H T T H E R E T O . 7/ 3 1 / 2 0 1 9 2 : 5 5 : 3 1 P M P: \ 7 0 0 5 0 0 1 2 \ W I P D R A W I N G S \ D r a i n a g e A r e a M a p . d w g sh o r t j CH R I S T I A N B R O T H E R S A U T O M O T I V E PR O P O S E D S E R V I C E CE N T E R CA R M E L , I N D I A N A 70050012 JPM JPM JRS DRAINAGE AREA MAP - DETENTION SIZING DRAINAGE AREA PERVIOUS AREA IMPERVIOUS AREA RUNOFF CURVE NUMBER RATIONAL RUNOFF COEFFICIENT TOTAL PROPERTY AREA 1.23 Ac 0.50 Ac 0.73 Ac 91 0.59 * PERVIOUS AREA IS OPEN SPACE IN GOOD CONDITION - HYDROLOGIC SOIL GROUP D *IMPERVIOUS AREA IS PAVED PARKING LOTS, ROOFS, AND DRIVEWAYS - HYDROLOGIC SOIL GROUP D *DETENTION CALCULATIONS FOR ARIA APARTMENT DETENTION BASIN ASSUMED A RUNOFF CURVE NUMBER OF 92.8 FOR THIS PROPERTY. -IMPERVIOUS AREA U S 4 2 1 ( M I C H I G A N R O A D ) G G G G W O H U O H U O H U O H U O H U O H U O H U O H U OHU OHU OHU OHU OHU AN D R A D E DR I V E LOT 2 0.25 AC LOT 1 5.86 ACLOT 3 14.56 AC W W WESTO N P O I N T E D R I V E RE D D R O A D OFF-N 0.39 AC OFF-E 0.41 AC DIR-N 0.17 AC DIR-S 1.22 AC DEV 13.99 AC FUT DEV 5.86 AC FI G U R E 3 . 2 PO S T - D E V E L O P E D B A S I N M A P Da t e : J u n e 2 9 , 2 0 1 8 WE I H E we i h e . n e t In d i a n a p o l i s , I n d i a n a 4 6 2 8 0 10 5 0 5 N . C o l l e g e A v e n u e 31 7 | 8 4 6 - 6 6 1 1 E N G I N E E R S MI C H I G A N R O A D S I T E ZI O N S V I L L E , I N Basin Type of Cover/ Percent Weighted Name A B C D Condition of Cover of Basin A B C D CN DEV 0% 0% 39% 61% Impervious (Pond Area) 8% 98 98 98 98 98.0 0% 0% 39% 61% Commercial 70% 89 92 94 95 94.6 0% 0% 39% 61% Open Space, Good Cond. 22% 39 61 74 80 77.7 DEV 100%91.2 FUT DEV 0% 0% 48% 52% Commercial 90% 89 92 94 95 94.5 0% 0% 48% 52% Open Space, Good Cond. 10% 39 61 74 80 77.1 FUT DEV 92.8 OFF-N 0% 80% 20% 0% Impervious 2% 98 98 98 98 98.0 0% 80% 20% 0% Open Space, Good Cond. 98% 39 61 74 80 63.6 OFF-N 64.3 OFF-E 0% 70% 30% 0% Impervious 12% 98 98 98 98 98.0 0% 70% 30% 0% Open Space, Good Cond. 88% 39 61 74 80 64.9 OFF-E 68.9 Weighted Curve Project:Michigan Road Site Number Calculations Date:6/29/2018 Prepared By:TPG Soil Group % Curve Number (CN) Job No.:W17-0567 Proposed Conditions Checked By:KCS WinTR-55 Current Data Description --- Identification Data --- User: ShortJ Date: 7/31/2019 Project: 70050012 - CBA Carmel Units: English SubTitle: Stormwater Runoff Calculations Areal Units: Acres State: Indiana County: Hamilton NOAA_A Filename: P:\70050012\WIP DRAWINGS\Civil\Calcs\TR-55 Stormwater Runoff Data - Drainage Area and Total Property.w55 --- Sub-Area Data --- Name Description Reach Area(ac) RCN Tc ------------------------------------------------------------------------------ CBA SITE PROPERTY AREA Outlet 1.23 91 .145 Total area: 1.23 (ac) --- Storm Data -- Rainfall Depth by Rainfall Return Period 2-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr 1-Yr (in) (in) (in) (in) (in) (in) (in) -------------------------------------------------------------------------------- 2.85 3.53 4.06 4.81 5.4 6.02 2.37 Storm Data Source: Hamilton NOAA_A County, IN (NRCS) Rainfall Distribution Type: Type II Dimensionless Unit Hydrograph: <standard> WinTR-55, Version 1.00.10 Page 1 7/31/2019 1:45:27 PM ShortJ 70050012 - CBA Carmel Stormwater Runoff Calculations Hamilton NOAA_A County, Indiana Sub-Area Land Use and Curve Number Details Sub-Area Hydrologic Sub-Area Curve Identifier Land Use Soil Area Number Group (ac) -------------------------------------------------------------------------------- CBA SITE Open space; grass cover > 75% (good) D .5 80 Paved parking lots, roofs, driveways D .73 98 Total Area / Weighted Curve Number 1.23 91 ==== == WinTR-55, Version 1.00.10 Page 1 7/31/2019 1:45:27 PM STORMWATER MANAGEMENT PLAN Christian Brothers Automotive Service Center 70050012 Stormwater Management Plan APPENDIX 4 Stormwater Design Calculations St o r m - D r a i n a g e D e s i g n S u m m a r y - R a t i o n a l M e t h o d Pr o j e c t N a m e : Ch r i s t i a n B r o t h e r s A u t o - C a r m e l , I N De s i g n e d B y : JR S Ch e c k e d B y : JP M Pr o j e c t # : 70 0 5 0 0 1 2 Da t e : 4/ 1 1 / 2 0 1 9 Da t e : Pr o j e c t L o c a t i o n : Ca r m e l , I n d i a n a Mo d i f i e d : 7/ 1 5 / 2 0 1 9 De s i g n A s s u m p t i o n s : Ma n n i n g ' s E q u a t i o n w h e r e n = 0.0 1 3 C o n c r e t e P i p e De s i g n S t o r m = 10 - Y e a r AL L N O N - S H A D E D C E L L S A R E I N P U T C E L L S . Min T c = 5. 0 0 min 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Pr o p o s e d P i p e N e t w o r k Dr a i n a g e A r e a s & C De s i g n F l o w Fu l l F l o w C o n d i t i o n s Hydraulic Grade Line Elevation Actual Flow Conditions Up p e r St r u c t u r e I D Lo w e r St r u c t u r e I D Pip e D i a m e t e r Pip e Le n g t h De s i g n S l o p e of P i p e ( S ) Up p e r I n v e r t El e v a t i o n Lo w e r I n v e r t El e v a t i o n Up p e r R i m El e v a t i o n Lo w e r R i m Ele v a t i o n In l e t D r a i n a g e Ar e a ( a c r e s ) We i g h t e d Ru n o f f Co e f f i c i e n t " C " Ti m e o f Co n c e n t r a t i o n (m i n ) In l e t C x A Su m o f C x A Ra i n f a l l In t e n s i t y ( i n / h r ) To t a l Ru n o f f De s i g n Flo w (c f s ) Flo w i n g Fu l l P i p e Ca p a c i t y Q= C 1 x S 1/2 (c f s ) Ma n n i n g ' s "C 1 " F a c t o r (1 . 4 9 / n ) x Ax R 2/3 Ve l o c i t y ( f t / s ) Tim e o f F l o w (m i n ) Slope of Energy Grade Line (ft/ft)Frictional Losses (ft)Minor Losses 1/2(V2 /2g) (ft)Total Hydraulic Head Loss (ft) HGL Upper* HGL LowerDepth of Hydraulic Grade Line below Upper Rim ElevationVelocityDepth of Flow (feet)Percent Full (D/do) YD - 3 C YD - 3 B 12 1 0 0 0 . 3 8 % 89 5 . 7 0 8 9 5 . 3 2 89 9 . 2 0 89 9 . 0 0 0 . 2 0 0 . 3 2 5 . 0 0 0 . 0 6 0 . 0 6 6 . 1 2 0 . 3 9 2 . 2 0 3 5 . 6 3 2 . 8 0 0 . 6 0 0 . 0 0 0 0 . 0 1 2 0 . 0 3 0 0 . 0 4 2 8 9 5 . 9 6 8 9 5 . 9 2 3 . 2 4 1 . 9 6 0 . 2 5 2 5 . 0 0 % YD - 3 B YD - 3 A 12 1 0 0 0 . 3 0 % 89 5 . 2 2 8 9 4 . 9 2 89 9 . 0 0 89 8 . 9 0 0 . 2 3 0 . 3 7 5 . 6 0 0 . 0 9 0 . 1 5 6 . 1 2 0 . 9 1 1 . 9 5 3 5 . 6 3 2 . 4 8 0 . 6 7 0 . 0 0 1 0 . 0 6 5 0 . 0 4 3 0 . 1 0 9 8 9 5 . 9 2 8 9 5 . 8 1 3 . 0 8 2 . 3 6 0 . 4 5 4 5 . 0 0 % YD - 3 A CB - 3 12 8 9 0 . 3 0 % 89 4 . 8 2 8 9 4 . 5 6 89 8 . 9 0 89 9 . 7 5 0 . 3 4 0 . 2 7 6 . 2 7 0 . 0 9 0 . 2 4 6 . 1 2 1 . 4 7 1 . 9 5 3 5 . 6 3 2 . 4 8 0 . 6 0 0 . 0 0 2 0 . 1 5 2 0 . 0 5 5 0 . 2 0 7 8 9 5 . 8 1 8 9 5 . 6 0 3 . 0 9 2 . 6 7 0 . 6 0 6 0 . 0 0 % YD - 5 A CB - 5 12 1 9 3 . 7 0 . 4 0 % 89 6 . 3 4 8 9 5 . 5 6 89 9 . 9 0 90 0 . 0 0 0 . 2 9 0 . 2 8 5 . 0 0 0 . 0 8 0 . 0 8 6 . 1 2 0 . 5 0 2 . 2 5 3 5 . 6 3 2 . 8 7 1 . 1 3 0 . 0 0 0 0 . 0 3 9 0 . 0 3 8 0 . 0 7 7 8 9 6 . 3 8 8 9 6 . 3 0 3 . 5 2 2 . 2 2 0 . 3 0 3 0 . 0 0 % CB - 5 CB - 4 12 1 0 2 . 5 0 . 5 0 % 89 5 . 4 6 8 9 4 . 9 5 90 0 . 0 0 89 8 . 8 5 0 . 2 8 0 . 9 0 6 . 1 3 0 . 2 5 0 . 3 4 6 . 1 2 2 . 0 5 2 . 5 2 3 5 . 6 3 3 . 2 1 0 . 5 3 0 . 0 0 3 0 . 3 3 9 0 . 0 9 7 0 . 4 3 6 8 9 6 . 3 0 8 9 5 . 8 7 3 . 7 0 3 . 5 3 0 . 6 5 6 5 . 0 0 % CB - 4 CB - 3 15 8 4 0 . 3 5 % 89 4 . 8 5 8 9 4 . 5 6 89 8 . 8 5 89 9 . 7 5 0 . 1 7 0 . 8 5 6 . 6 6 0 . 1 5 0 . 4 8 6 . 1 2 2 . 9 5 3 . 8 2 6 4 . 6 0 3 . 1 1 0 . 4 5 0 . 0 0 2 0 . 1 7 5 0 . 0 9 1 0 . 2 6 6 8 9 5 . 8 7 8 9 5 . 6 0 2 . 9 8 3 . 4 3 0 . 8 1 6 5 . 0 0 % CB - 3 CB - 2 18 2 1 0 . 2 5 % 89 4 . 4 6 8 9 4 . 4 0 89 9 . 7 5 90 0 . 0 5 0 . 0 5 0 . 9 5 7 . 1 1 0 . 0 5 0 . 7 7 6 . 1 2 4 . 7 3 5 . 2 5 1 0 5 . 0 5 2 . 9 7 0 . 1 2 0 . 0 0 2 0 . 0 4 3 0 . 0 8 7 0 . 1 2 9 8 9 5 . 6 0 8 9 5 . 4 7 4 . 1 5 3 . 3 4 1 . 0 5 7 0 . 0 0 % CB - 2 CB - 1 18 5 5 0 . 2 5 % 89 4 . 3 0 8 9 4 . 1 7 90 0 . 0 5 89 9 . 4 3 0 . 0 1 0 . 3 6 7 . 2 2 0 . 0 0 0 . 7 8 6 . 1 2 4 . 7 6 5 . 2 5 1 0 5 . 0 5 2 . 9 7 0 . 3 1 0 . 0 0 2 0 . 1 1 3 0 . 0 8 7 0 . 2 0 0 8 9 5 . 4 7 8 9 5 . 2 7 4 . 5 8 3 . 3 4 1 . 0 5 7 0 . 0 0 % CB - 1 C B 2 . 2 1 8 4 6 0 . 2 5 % 89 4 . 0 7 89 3 . 9 5 8 9 9 . 4 3 n/ a 0 . 0 8 0 . 7 0 7 . 5 3 0 . 0 5 0 . 8 3 6 . 1 2 5 . 0 9 5 . 2 5 1 0 5 . 0 5 2 . 9 7 0 . 2 6 0 . 0 0 2 0 . 1 0 8 0 . 0 8 9 0 . 1 9 7 8 9 5 . 2 7 8 9 5 . 0 8 4 . 1 6 3 . 3 9 1 . 1 3 7 5 . 0 0 % To t a l D r a i n a g e A r e a = T o t a l C x A = 0 . 8 3 Ma n n i n g ' s " C 1 " F a c t o r = ( 1 . 4 9 / n ) x ( A ) x ( R 2/3 ) * Starting HGL calculation is set based on actual depth of flow. 1.6 5 W e i g h t e d S i t e " C " = 0 . 5 0 Q = " C 1 " x S 1/2 * HGL is max value of downstream HGL or actual flow elevation.* Check outlet storm sewer crown or Basin HWL for starting HGL P: \ 7 0 0 5 0 0 1 2 \ W I P D R A W I N G S \ C i v i l \ C a l c s \ C B A C a r m e l - M a s t e r S t o r m . x l s m / S t o r m S e w e r 1 0 - Y R 8/ 2 / 2 0 1 9 Project: Christian Brothers Auto - Carmel, IN Project # 70050012 Prepared By: JRS Subject: Stormwater Detention Basin Sizing Reviewed By: Date: Revised: Determination of Post-Development Peak Discharge from Site 10-year and 100-year Storm Events Rational Method Design Information: Site Information: Total Area of Proposed Development =1.23 Acres Impervious Area =0.73 Acre Pervious Area = 0.50 Impervious "C" Factor =0.90 Pervious "C" Factor =0.30 Weighted "C" Factor for Post-Development Area of Site =0.59 Storm Information: Time of Concentration = 8.00 Min 10-Year Storm Intensity (5-min) = 6.12 in/hr 100-year Storm Intensity (5-min) = 9.12 in/hr Peak Discharge Rates: 10-Year Peak Discharge = 4.47 cfs 100-Year Peak Discharge = 6.67 cfs * These rates represent the discharge from the Christian Brothers site. Restricted release to allowable rates will be accomplised from the detention basin on the Aria Development. May 30, 2019 P:\70050012\WIP DRAWINGS\Civil\Calcs\CBA Carmel - Master Storm.xlsm/STORM DISCHARGE 8/2/2019