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Home My WebLink AboutCUP 2018-0023; BUENA VISTA RESERVOIR SITE (PARK); DRAINAGE STUDY BUENA VISTA RESERVOIR SITE; 2020-05-20DRAINAGE STUDY FOR: BUENA VISTA RESERVOIR SITE APN 156-200-16 1605 BUENA VISTA WAY, CARLSBAD, CA 92008 CUP2018-0023 I GR2019-0040 I DWG 521-IA 1ThTT,—r 'r' fl4LIJ4iL Yii P •. H ] U LL nj LAND DEVELOPMENT ENGINENC Prepared For: SCHMIDT DESIGN GROUP, INC. 1310 ROSECRANS STREET, SUITE G SAN DIEGO, CA 92106 (619) 236-1462 Prepared By: LATITUDE 33 PLANNING AND ENGINEERING 9968 HIBERT STREET 2ND FLOOR SAN DIEGO, CA 92131 (858) 751 - 0633 oFESS,0 (b No. 67697 OF CA01 Nick Psyhogios Date Prepared by: JG RCE 67697 Expires: 06/2021 Reviewed by: NP TABLE OF CONTENTS Executive Summary Page # Purpose 2 Project Description 2 Vicinity Map 2 Existing Conditions 3 Proposed Conditions 3 Water Quality 4 Discussion and Conclusions 5 Methodology & Model Development County of San Diego and City of Carlsbad Drainage Design Criteria 8 Rational Method Hydrologic Analysis 9 Appendix 17 Existing Hydrology Map Proposed Hydrology Map Hydrology Calculations Maps and References 18 Isopluvial Maps Excerpts from County of San Diego Hydrology Manual ilPage EXISTING CONDITION Under pre-project conditions, the site is in a mass graded state, but has not been built out. Ground coverage consists primarily of scattered grasses and bushes, exposed soil, and some impervious pavement serving as a vehicle access road. The existing drainage pattern for the site directs runoff as surface flow to the adjacent parcels to the East, South, and West and to Buena Vista Way to the North. From here, storm water continues to surface flow until reaching existing offsite storm drain infrastructure where it is then conveyed and discharged into Buena Vista Lagoon. The existing impervious portion of the project is under a sump condition and can hold up to 300,000 cubic feet of water before overflowing into the existing stand pipe. This basin shown as E40 on the Existing Hydrology Map is considered self-retaining since does not contribute to the overall outfall of the project site. PROPOSED CONDITION This project proposes to construct a public park consisting primarily of landscaping and garden areas with some impervious concrete walkways and plazas for pedestrian circulation. A brow ditch will be constructed along the West, East, and South edges of the property to prevent runoff from leaving the site and flowing into the adjacent parcels. Additionally, public improvements consisting of on-street parking stalls, concrete sidewalk, curb ramps, and crosswalk striping are proposed along the Northern edge of the lot where it meets the Southern edge of Buena Vista Way. The majority of onsite storm water will fall on or be dispersed to pervious landscaping areas before being directed to a proposed biofiltration (BF-1) BMP at the Northwest corner of the project site. WATER QUALITY AND HYDROMODIFICATION The post-construction phase of this project will require permanent BMPs designed to minimize discharge of pollutants generated on-site throughout the life of the project. The proposed water quality BMP for the project will include landscape and irrigated areas, and a biofiltration basin. Priority development projects are also required to implement hydromodification mitigation measures so that post-project runoff flow rates and durations do not exceed the pre-project where such increases would result in a potential for increase erosion or significant impacts to beneficial uses. The proposed biofiltration basin will also provide the required hydromodification mitigation. For more details regarding the onsite BMP see the Storm Water Quality Management Plan for the project. DISCUSSION AND CONCLUSIONS The onsite drainage areas for this project encompass approximately 3.16-acres and is the limit of the drainage analysis for this report. 3Page Methodology & Model Development County of San Diego and City of Carlsbad Drainage Design Criteria Rational Method Hydrologic Analysis 7Page METHODOLOGY & MODEL DEVELOPMENT The proposed development was analyzed in conformance with the County of San Diego Hydrology Manual, dated June 2003 and the City of Carlsbad Drainage Standards. The total area of all basins analyzed are less than one square mile. Therefore, the Rational Method was utilized to calculate peak storm runoff. The design is based upon the following: 1) Within floodplain and floodplain fringe areas as defined by the Federal Emergency Management Agency (FEMA), runoff calculations shall be based upon a 100-year frequency storm. 2) For all drainage channels and storm drain systems which will convey drainage from a tributary area greater than or equal to one square mile, runoff calculations shall be based upon a 100-year frequency storm. 3) For tributary areas under 1 square mile: The storm drain system shall be designed to carry 10-year, 6-hour underground and 100-year, 6-hour storm within top of curbs so that the combination of storm drain system capacity and overflow both inside and outside the right of way will be able to carry the 100-year frequency storm without damaging adjacent existing buildings or potential building sites. All culverts must be designed with 1 ft of freeboard at inlets and headwalls for the 100-year, 6-hour storm. The storm drain system shall be designed so that the combination of storm drain system capacity and allowable Street overflow will be able to carry the 100-year frequency Storm without damaging adjacent property. Where a storm drain is required under headings 1 or 2 above, then as a minimum, the drain shall be designed to carry the 10-year frequency storm. 4) Sump areas are to be designed for a sump capacity or outfall of a 100-year frequency storm. 5) Type B soil shall be used for all areas. 8Page Rational Method Hydrologic Analysis Design Storm - 100-year/50-year return interval Land Use - Residential / Multifamily Soil Type - Based on geotechnical borings Hydrologic soil group B covers 99% of the project area, therefore soil group B was assured for all areas. Runoff Coefficient - In accordance with the County of San Diego Hydrology Manual, runoff coefficients are as followed: Undisturbed Natural Terrain uses a coefficient of 0.25. Low Density Residential (LDR) uses a coefficient of 0.32-0.41. Medium Density Residential uses a coefficient of 0.45-0.58. High Density Residential uses a coefficient of 0.0.67-0.77. Commercial/Industrial uses a coefficient of 0.77-0.87. When a watershed encompasses solely pavement conditions, a runoff coefficient of 0.95 was selected. Method of Analysis - The Rational Method is the most widely used hydrologic model for estimating peak runoff rates. Applied to small urban and semi-urban areas with drainage areas less than 0.5 square miles, the Rational Method relates storm rainfall intensity, a runoff coefficient, and drainage area to peak runoff rate. This relationship is expressed by the equation: Q=CIA, where: Q = The peak runoff rate in cubic feet per second at the point of analysis. C = A runoff coefficient representing the area - averaged ratio of runoff to rainfall intensity. = The time-averaged rainfall intensity in inches per hour corresponding to the time of concentration. A = The drainage basin area in acres. Computer Software - Autodesk Storm and Sanitary Analysis 2018 This software uses the San Diego County Hydrology Manual standards to calculate time of concentration. The intensity-duration-frequency curves used in the analysis are from the County of San Diego. Design Storm - 100-year/50-year return interval 9Page Appendix Existing Hydrology Map Proposed Hydrology Map Hydrology Calculations 101 P a g e :will ~ 0 =61 !;1YL.] [am ll 111=w=uNl% mloNowl 0 VA ØJØ]0--1*- VA LTA FA1 MAJOR BASIN DI WOE/PROJECT LIMITS II SURFACE DRAINAGE PATTERNS STORM DRAIN PIPE DRAINAGE PATTERNS STORM DRAIN PIPE FLOWLINE BASIN DATA X BASIN NUMBER Q100/050 VELOCITY BASIN AREA / 4 / MODIFIED SORSO D-75 TYPE '0' CONCRETE BROW DITCH / , ' 7j JUNC11ON Ji 12" PVC STORM DRAIN PIPE,-45 LF GFZ 164.0 IL / / 0 \ / / / / N / o 25 50 100 150 ( IN FEET ) l inch =50 ft. 6 11:16:31 AM - SdmWt Design - T U 0 !;1YL.]I:1111 ;[Luj t wj;lAw i1 MAJOR BASIN DI WDE/PROJECT LIMITS DRAINAGE PA 1TERNS FLOWLINE FOR liME OF CONCENTRA liON amewm MOM= ago" EXIS71NG CHANNEL FLOWLINE X BASIN NUMBER BASIN DATA Q100/Q50 VELOCITY BASIN AREA o 15 30 60 90 ( IN FEET ) 1 inch = 30 ft. - SdWth D.0 - AM Con4t4onLdwQ 50 YEAR EXISTING CONDITIONS I Autodesk5 Storm and Sanitary Analysis 2016 - Version 12.0.42 (Build 0) ----------------------------------------------------------------------------------------- Proj ect Description ** * * ** * * * ** * ** File Name .................EX conditions.SPF Analysis Options Flow Units ................cfs Subbasin Hydrograph Method. Rational Time of Concentration ......FAA Return Period..............50 years Storage Node Exfiltration.. Constant rate, free surface area Starting Date ............. DEC-12-2018 00:00:00 Ending Date ...............DEC-12-2018 07:00:00 Report Time Step ..........00:00:10 Element Count Number of subbasins .......4 Number of nodes ...........4 Number of links ...........0 Subbasin Summary Subbasin Total Flow Average Area Length Slope ID acres ft --------------------------------------------------- E1O 1.00 268.00 7.2000 E20 0.45 91.00 9.5000 E30 0.51 91.00 19.6700 E40 0.85 298.00 3.2000 ************ Node Summary Node Element Invert Maximum Ponded External ID Type Elevation Elev. Area inflow ft ft ft2 POCO1 OUTFALL ------------------------------------------------------------------------------ 0.00 0.00 0.00 P00O2 OUTFALL 0.00 0.00 0.00 P00O3 OUTFALL 0.00 0.00 0.00 P0004 OUTFALL 0.00 0.00 0.00 Volume Depth Runoff Quantity Continuity acre-ft inches Total Precipitation 0.135 0.575 Continuity Error (%) 0.530 Volume Volume Flow Routing Continuity acre-ft Mgallons Autodesk Storm and Sanitary Analysis External Inflow 0.000 0.000 External Outflow 0.063 0.021 Initial Stored Volume . . . 0.000 0.000 Final Stored Volume 0.000 0.000 Continuity Error (%) 0.000 * ** * * ************** * ************ * * * * ** Runoff Coefficient Computations Report ** ** * * * * ************* * ------------ Subbasin ElO Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ------------------------------------------------------------------------------------------ - 1.23 B 0.32 Composite Area & Weighted Runoff Coeff. 1.23 0.32 ------------ Subbasin E20 Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- - 0.45 B 0.32 Composite Area & Weighted Runoff Coeff. 0.45 0.32 --------------- Subbasin E30 --------------- Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- - 0.51 B 0.32 Composite Area & Weighted Runoff Coeff. 0.51 0.32 --------------- Subbasin E40 --------------- Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- Concrete 0.85 B 0.90 Composite Area & Weighted Runoff Coeff. 0.85 0.90 * * * * * * ********************** * FAA (Federal Aviation Agency) Time of Concentration Computations Report ************* ******** ** ******** * * * * * * * ******* ************* * * Tc = (1.8 * (1.1 - C) * (L0.5) * (S-0.333)) Where: Tc = Time of Concentration (mm) C = Runoff Coefficient L = Flow Length (ft) S = Slope (%) --------------- Subbasin E10 --------------- Runoff Coefficient: 0.32 Flow Length (ft) : 268.00 Autodesk Stonn and Sanitary Analysis Slope M: 7.20 Computed TOC (minutes): 11.91 --------------- Subbasin E20 --------------- Runoff Coefficient: 0.32 Flow Length (ft) : 91.00 Slope (U : 9.50 Computed TOC (minutes): 6.33 --------------- Subbasin E30 --------------- Runoff Coefficient: 0.32 Flow Length (ft): 91.00 Slope (,V): 19.67 Computed TOC (minutes): 4.97 --------------- Subbasin E40 --------------- Runoff Coefficient: 0.90 Flow Length (ft) : 298.00 Slope (U: 3.20 Computed TOC (minutes): 4.22 Subbasin Runoff Summary Subbasin Accumulated Rainfall Total Peak Weighted Time of ID Precip Intensity Runoff Runoff Runoff Concentration in in/hr in cfs Coeff days hh:mm:ss E1O 0.68 3.46 --------------------------------------------------------------------------------------- 0.22 1.11 0.320 0 00:11:54 E20 0.55 5.20 0.18 0.75 0.320 0 00:06:19 E30 0.50 6.06 0.16 0.99 0.320 0 00:05:00 E40 0.50 6.06 --------------------------------------------------------------------------------------- 0.45 4.64 0.900 0 00:05:00 Analysis began On: Tue Feb 19 12:05:00 2019 Analysis ended On: Tue Feb 19 12:05:00 2019 Total elapsed time: < 1 sec Autodesk Storm and Sanitary Analysis 100 YEAR EXISTING CONDITIONS Autodeske Storm and Sanitary Analysis 2016 - Version 12.0.42 (Build 0) - Project Description File Name .................EX conditions.SPF Analysis Options Flow Units ................cfs Subbasin Hydrograph Method. Rational Time of Concentration ......FAA Return Period..............100 years Storage Node Exfiltration.. Constant rate, free surface area Starting Date .............DEC-12-2018 00:00:00 Ending Date ...............DEC-12-2018 07:00:00 Report Time Step ..........00:00:10 ************* Element Count Number of subbasins .......4 Number of nodes ...........4 Number of links ...........0 Subbasin Summary Subbasin Total Flow Average Area Length Slope ID acres ft --------------------------------------------------- E1O 1.00 268.00 7.2000 E20 0.45 91.00 9.5000 E30 0.51 91.00 19.6700 E40 0.85 298.00 3.2000 Node Summary Node Element Invert Maximum Ponded External ID Type Elevation Elev. Area Inflow ft ft ft2 POCO1 OUTFALL ------------------------------------------------------------------------------ 0.00 0.00 0.00 P00O2 OUTFALL 0.00 0.00 0.00 P00O3 OUTFALL 0.00 0.00 0.00 P0004 OUTFALL 0.00 0.00 0.00 Volume Depth Runoff Quantity Continuity acre-ft inches Total Precipitation 0.152 0.650 Continuity Error (%) 0.530 Volume Volume Flow Routing Continuity - ---------------- acre-ft Mgal1ons -------- Autodesk Storm and Sanitary Analysis External Inflow 0.000 0.000 External Outflow 0.072 0.023 Initial Stored Volume 0.000 0.000 Final Stored Volume 0.000 0.000 Continuity Error (%) 0.000 * ** * * * Runoff Coefficient Computations Report ************************************** --------------- Subbasin ElO --------------- Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- - 1.23 B 0.32 Composite Area & Weighted Runoff Coeff. 1.23 0.32 ------------ Subbasin E20 Area Soil Runoff Soil/Surface Description (acres) Group Coeff. - 0.45 B 0.32 Composite Area & Weighted Runoff Coeff. 0.45 0.32 --------------- Subbasin E30 --------------- Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- - 0.51 B 0.32 Composite Area & Weighted Runoff Coeff. 0.51 0.32 ------------ Subbasin E40 Area Soil Runoff Soil/Surface Description (acres) Group Coeff. Concrete 0.85 B 0.90 Composite Area & Weighted Runoff Coeff. 0.85 0.90 *********************************************************************** FAA (Federal Aviation Agency) Time of Concentration Computations Report ** ***** * * ******************************* * * Tc = (1.8 * (1.1 - C) * (L0.5) * (S-0.333)) Where: Tc = Time of Concentration (mm) C = Runoff Coefficient L = Flow Length (ft) S = Slope (%) --------------- Subbasin E10 --------------- Runoff Coefficient: 0.32 Flow Length (ft) : 268.00 Autodesk Storm and Sanitary Analysis Slope (10: 7.20 Computed TOC (minutes): 11.91 --------------- Subbasin E20 --------------- Runoff Coefficient: 0.32 Flow Length (ft): 91.00 Slope (t): 9.50 Computed TOC (minutes): 6.33 --------------- Subbasin 530 --------------- Runoff Coefficient: 0.32 Flow Length (ft): 91.00 Slope (%): 19.67 Computed TOC (minutes): 4.97 --------------- Subbasin E40 --------------- Runoff Coefficient: 0.90 Flow Length (ft) : 298.00 Slope M: 3.20 Computed TOC (minutes): 4.22 Subbasin Runoff Summary Subbasin Accumulated Rainfall --------------------------------------------------------------------------------------- Total Peak Weighted Time of ID Precip Intensity Runoff Runoff Runoff Concentration in in/hr in cfs Coeff days hh:mm:ss 510 0.77 3.91 --------------------------------------------------------------------------------------- 0.25 1.25 0.320 0 00:11:54 E20 0.62 5.88 0.20 0.85 0.320 0 00:06:19 E30 0.57 6.85 0.18 1.12 0.320 0 00:05:00 E40 0.57 6.85 --------------------------------------------------------------------------------------- 0.51 5.24 0.900 0 00:05:00 Analysis began On: Wed Dec 12 09:07:21 2018 Analysis ended On: Wed Dec 12 09:07:22 2018 Total elapsed time: 00:00:01 Autodesk Stan,, and Sanitary Analysis 50 YEAR PROPOSED CONDITIONS I Autodesk® Storm and Sanitary Analysis 2016 - Version 12.0.42 (Build 0) ----------------------------------------------------------------------------------------- Proj ect Description ** * ** ** ** * * File Name .................PR Conditions.SPF Analysis Options Flow Units ................ Cf 5 Subbasin Hydrograph Method Rational Time of Concentration ......FAA Return Period..............50 years Link Routing Method .......Steady Flow Storage Node Exfiltration.. Constant rate, free surface area Starting Date .............DEC-04-2018 00:00:00 Ending Date ...............DEC-04-2018 06:00:00 Report Time Step ..........00:00:10 Element Count Number of subbasins .......2 Number of nodes ...........6 Number of links ...........4 * ********* * * * * ** Subbasin Summary Subbasin Total Flow Average Area Length Slope ID acres ft S1O --------------------------------------------------- 2.38 386.00 3.1000 S20 0.52 729.00 3.0000 ************ Node Summary Node Element Invert Maximum Ponded External ID Type Elevation Elev. Area Inflow ft ft ft J1 JUNCTION ------------------------------------------------------------------------------ 166.10 169.85 0.00 PlO OUTFALL 164.00 164.83 0.00 Yes SO-1 OUTFALL 0.00 0.00 0.00 SO-20 OUTFALL 0.00 0.00 0.00 SUBSURFACE STORAGE 165.85 168.85 0.00 SURFACE STORAGE 168.85 170.10 0.00 Yes * ********* * * Link Summary Link From Node To Node Element Length Slope Manning's ID -------------------------------------------------------------------------------------------- Type ft % Roughness Link-Ol ii PlO CONDUIT 46.0 4.5652 0.0110 LOWFLOW SUBSURFACE Ji ORIFICE OVERFLOW SURFACE Ji ORIFICE Autodesk Storm and Sanitary Analysis INF_5 IN/HR SURFACE SUBSURFACE OUTLET Cross Section Summary Link Shape Depth/ Width No. of Cross Full Flow Design ID Diameter Barrels Sectional Hydraulic Flow Area Radius Capacity ft ft ft2 ft Cf S ------------------------------------------------------------------------------------------------- Link-Ol CIRCULAR 0.83 0.83 1. 0.55 0.21 5.53 Volume Depth Runoff Quantity Continuity acre-ft inches Total Precipitation 0.201 0.831 Continuity Error (%) 0.683 Volume Volume Flow Routing Continuity acre-ft Mgallons External Inflow 0.173 0.056 External Outflow 0.101 0.033 Initial Stored Volume ... 0.000 0.000 Final Stored Volume 0.135 0.044 Continuity Error (%) 0.000 Runoff Coefficient Computations Report ------------ Subbasin Sb Area Soil Runoff Soil/Surface Description (acres) Group Coeff. ----------------------------------------------------------------------------------------- Residential_1DU/AC_or_sess 2.38 B 0.32 Composite Area & Weighted Runoff Coeff. 2.38 0.32 ------------ Subbasin S20 Area Soil Runoff Soil/Surface Description (acres) Group Coeff. Residential_1DU/AC_or_sess 0.50 B 0.32 Composite Area & Weighted Runoff Coeff. 0.50 0.32 FAA (Federal Aviation Agency) Time of Concentration Computations Report Tc = (1.8 * (1.1 - C) * (L0.5) * (S-0.333)) Autodesk Storm and Sanitary Analysis Where: Tc Time of Concentration (mm) C = Runoff Coefficient L = Flow Length (ft) S • Slope (%) --------------- Subbasin S10 --------------- Runoff Coefficient: 0.32 Flow Length (ft) : 386.00 Slope (t): 3.10 Computed TOC (minutes): 18.93 --------------- Subbasin S20 --------------- Runoff Coefficient: 0.32 Flow Length (ft) : 729.00 Slope (t): 3.00 Computed TOC (minutes): 26.29 Subbasin Runoff Summary Subbasin Accumulated Rainfall --------------------------------------------------------------------------------------- Total Peak Weighted Time of ID Precip Intensity Runoff Runoff Runoff Concentration in in/hr in cfs Coeff days hh:mm:ss Sb 0.81 2.57 --------------------------------------------------------------------------------------- 0.26 1.96 0.320 0 00:18:55 S20 0.91 2.08 --------------------------------------------------------------------------------------- 0.29 0.35 0.320 0 00:26:17 Node Depth Summary Node Average Maximum Maximum ----------------------------------------------------------------------------------------- Time of Max Total Total Retention ID Depth Depth HGL Occurrence Flooded Time Time Attained Attained Attained Volume Flooded ft ft ft days hh:mm acre-in minutes hh:mm:ss J1 0.02 0.09 166.19 ----------------------------------------------------------------------------------------- 0 04:27 0 0 0:00:00 PlO 0.02 0.09 164.09 0 04:27 0 0 0:00:00 SO-1 0.00 0.00 0.00 0 00:00 0 0 0:00:00 SO-20 0.00 0.00 0.00 0 00:00 0 0 0:00:00 SUBSURFACE 0.66 1.67 167.52 0 06:00 0 0 0:00:00 SURFACE 0.34 1.04 169.89 0 04:27 0 0 0:00:00 Node Flow Summary ------------------------------------------------------------------------------------ Node Element Maximum Peak Time of Maximum Time of Peak ID Type Lateral Inflow Peak Inflow Flooding Flooding Inflow Occurrence Overflow Occurrence cfs cfs days hh:mm cfs days hh:mm ------------------------------------------------------------------------------------ Autodesk Storm and Sanitary Analysis J]. JUNCTION 0.00 0.13 0 04:27 0.00 PlO OUTFALL 0.35 0.36 0 04:12 0.00 SO-1 OUTFALL 1.96 1.96 0 00:19 0.00 SO-20 OUTFALL 0.35 0.35 0 00:26 0.00 SUBSURFACE STORAGE 0.00 0.28 0 03:24 0.00 SURFACE STORAGE 1.96 1.96 0 04:09 0.00 Storage Node Summary Storage Node ID Maximum Maximum Time of Max Average Average Maximum Maximum Time of Max. Total Ponded Ponded Ponded Ponded Ponded Storage Node Exfiltration Exfiltration Exfiltrated Volume Volume Volume Volume Volume Outflow Rate Rate Volume 1000 ft (%) days hh:mm 1000 ft (%) cfs cfm hh:mm:ss 1000 ft ------------------------------------ SUBSURFACE 4.079 56 ------------------------------------------------------------------------------------------------- 0 06:00 1.599 22 0.03 0.00 0:00:00 0.000 SURFACE 2.543 83 0 04:27 0.835 27 0.39 0.00 0:00:00 0.000 Outfall Loading Summary Outfall Node ID Flow Average Peak Frequency Flow Inflow (%) cfs cfs P10 ----------------------------------------------- 99.48 0.08 0.36 SO-1 10.55 0.98 1.96 SO-20 14.59 0.17 0.35 System ----------------------------------------------- 41.54 1.23 2.21 Link Flow Summary ------------------------------------------------------------------------------------------------- ------------------------------- Link ID Element Time of Maximum Length Peak Flow Design Ratio of Ratio of Total Reported Type Peak Flow Velocity Factor during Flow Maximum Maximum Time Condition Occurrence Attained Analysis Capacity /Design Flow Surcharged days hh:mm ft/sec cfs cfs Flow Depth minutes -------------------------------------------------------------------------------------------------------------------------------- Link-Ol CONDUIT 0 04:27 3.95 1.00 0.13 5.53 0.02 Autodesk Storm and Sanitary Analysis 0.11 0 Calculated LOWFLOW ORIFICE 0 06:00 0.03 0.00 OVERFLOW ORIFICE 0 04:27 0.11 INF_51N/HR OUTLET 0 03:24 0.28 Highest Flow Instability Indexes All links are stable. WARNING 107 : Initial water surface elevation defined for Junction Jl is below junction invert elevation. Assumed initial water surface elevation equal to invert elevation. WARNING 108 : Surcharge elevation defined for Junction Jl is below junction maximum elevation. Assumed surcharge elevation equal to maximum elevation. WARNING 110 : Initial water surface elevation defined for Storage Node SUBSURFACE is below storage node invert elevation. Assumed initial water surface elevation equal to invert elevation. WARNING 110 : Initial water surface elevation defined for Storage Node SURFACE is below storage node invert elevation. Assumed initial water surface elevation equal to invert elevation. Analysis began on: Tue Feb 19 11:47:01 2019 Analysis ended on: Tue Feb 19 11:47:02 2019 Total elapsed time: 00:00:01 Autodesk Storm and Sanitary Analysis 100 YEAR PROPOSED CONDITIONS Autodesk® Storm and Sanitary Analysis 2016 - Version 12.0.42 (Build 0) ----------------------------------------------------------------------------------------- Project Description File Name .................PR Conditions.SPF Analysis Options Flow Units ................cfs Subbasin Hydrograph Method Rational Time of Concentration......FAA Return Period ..............100 years Link Routing Method .......Steady Flow Storage Node Exfiltration.. Constant rate, free surface area Starting Date .............DEC-04-2018 00:00:00 Ending Date ...............DEC-04-2018 06:00:00 Report Time Step ..........00:00:10 Element Count Number of subbasins .......2 Number of nodes ...........6 Number of links ...........4 * ******** * * Subbasin Summary **************** Subbasin Total Flow Average Area Length Slope ID acres ft S1O --------------------------------------------------- 2.38 386.00 3.1000 S20 0.52 729.00 3.0000 Node Summary Node Element Invert Maximum Ponded External I'D Type Elevation Elev. Area Inflow ft ft ft2 Jl JUNCTION ------------------------------------------------------------------------------ 166.10 169.85 0.00 PlO OUTFALL 164.00 164.83 0.00 Yes SO-1 OUTFALL 0.00 0.00 0.00 SO-20 - OUTFALL 0.00 0.00 0.00 SUBSURFACE STORAGE 165.85 168.85 0.00 SURFACE STORAGE 168.85 170.10 0.00 Yes Link Summary Link From Node To Node Element Length Slope manning 's ID Type ft % Roughness Link-Ol Jl PlO -------------------------------------------------------------------------------------------- CONDUIT 46.0 4.5652 0.0110 LOWFLOW SUBSURFACE Jl ORIFICE OVERFLOW SURFACE Jl ORIFICE Autodesk Stomi and Sanitary Analysis INF_51N/HR SURFACE SUBSURFACE OUTLET Cross Section Summary Link Shape Depth! Width No. of Cross Full Flow Design ID Diameter Barrels Sectional Hydraulic Flow Area Radius Capacity ft ft ft2 ft cfs ------------------------------------------------------------------------------------------------- Link-Ol CIRCULAR 0.83 0.83 1 0.55 0.21 5.53 Volume Depth Runoff Quantity Continuity acre-ft inches Total Precipitation 0.227 0.939 Continuity Error (%) 0.683 Volume Volume Flow Routing Continuity acre-ft Mgallons External Inflow 0.196 0.064 External Outflow 0.125 0.041 Initial Stored Volume .. 0.000 0.000 Final Stored Volume 0.142 0.046 Continuity Error (%) 0.000 Runoff Coefficient Computations Report --------------- Subbasin Sb --------------- Area Soil Runoff Soil/Surface Description (acres) Group Coeff. Residential_1DU/AC_or_sess 2.38 B 0.32 Composite Area & Weighted Runoff Coeff. 2.38 0.32 --------------- Subbasin S20 --------------- Area Soil Runoff Soil/Surface Description ----------------------------------------------------------------------------------------- (acres) Group Coeff. Residential_1DU/AC_or_sess 0.50 B 0.32 Composite Area & Weighted Runoff Coeff. 0.50 0.32 FAA (Federal Aviation Agency) Time of Concentration Computations Report ** * ****************** * ** * ********** ****************** ** * * * Tc (1.8 * (1.1 - C) * (L0.5) * (S-0.333)) Autodesk Storm and Sanitary Analysis Where: Tc = Time of Concentration (mm) C = Runoff Coefficient L = Flow Length (ft) S = Slope (%) --------------- Subbasin Sb --------------- Runoff Coefficient: 0.32 Flow Length (ft) : 386.00 Slope (%): 3.10 Computed TOC (minutes): 18.93 --------------- Subbasin S20 --------------- Runoff Coefficient: 0.32 Flow Length (ft) : 729.00 Slope (%): 3.00 Computed TOC (minutes): 26.29 Subbasin Runoff Summary Subbasin Accumulated Rainfall Total Peak Weighted Time of ID Precip Intensity Runoff Runoff Runoff Concentration in in/hr in cfs Coeff days hh:mm:ss SlO 0.92 2.90 --------------------------------------------------------------------------------------- 0.29 2.21 0.320 0 00:18:55 S20 1.03 2.35 --------------------------------------------------------------------------------------- 0.33 0.39 0.320 0 00:26:17 Node Depth Summary Node Average Maximum ----------------------------------------------------------------------------------------- Maximum Time of Max Total Total Retention ID Depth Depth HGL Occurrence Flooded Time Time Attained Attained Attained Volume Flooded ft ft ft days hh:mm acre-in minutes hh:mm:ss J1 0.03 0.19 166.29 0 04:22 0 0 0:00:00 PlO 0.03 0.19 164.19 0 04:22 0 0 0:00:00 SO-1 0.00 0.00 0.00 0 00:00 0 0 0:00:00 SO-20 0.00 0.00 0.00 0 00:00 0 0 0:00:00 SUBSURFACE 0.71 1.75 167.60 0 06:00 0 0 0:00:00 SURFACE 0.37 1.13 169.98 0 04:22 0 0 0:00:00 Node Flow Summary Node Element Maximum Peak Time of Maximum Time of Peak ID Type Lateral Inflow Peak Inflow Flooding Flooding Inflow Occurrence Overflow Occurrence cfs cfs days hh:mm cfs days hh:mm ------------------------------------------------------------------------------------ Autodesk Storm and Sanitary Analysis Jl JUNCTION 0.00 0.63 0 04:22 0.00 PlO OUTFALL 0.39 0.89 0 04:21 0.00 SO-1 OUTFALL 2.21 2.21 0 00:19 0.00 SO-20 OUTFALL 0.39 0.39 0 00:26 0.00 SUBSURFACE STORAGE 0.00 0.28 0 03:15 0.00 SURFACE STORAGE 2.21 2.21 0 04:09 0.00 ** * * * **** Storage Node Summary Storage Node ID Maximum Maximum Time of Max Average Average Maximum Maximum Time of Max. Total Ponded Ponded Ponded Ponded Ponded Storage Node Exfiltration Exfiltration Exfiltrated Volume Volume Volume Volume Volume Outflow Rate Rate Volume 1000 ft (%) days hh:mm 1000 ft3 (%) cfs cfm hh:mm:ss 1000 ft ------------------------------------ SUBSURFACE 4.270 58 ------------------------------------------------------------------------------------------------- 0 06:00 1.728 24 0.03 0.00 0:00:00 0.000 SURFACE 2.754 90 0 04:22 0.897 29 0.89 0.00 0:00:00 0.000 Outfall Loading Summary Outfall Node ID ---------------------------------------------- Flow Average Peak Frequency Flow Inflow (%) cfs cfs PlO ----------------------------------------------- 99.55 0.11 0.89 SO-1 10.55 1.11 2.21 SO-20 14.59 0.20 0.39 System ----------------------------------------------- 41.56 1.41 2.50 ***************** Link Flow Summary Link ID Element Time of Maximum Length Peak Flow Design Ratio of Ratio of Total Reported Type Peak Flow Velocity Factor during Flow Maximum Maximum Time Condition Occurrence Attained Analysis Capacity /Design Flow Surcharged days hh:mm ft/sec cfs cfs Flow Depth minutes ------------------------------- Link-Ol CONDUIT 0 04:22 6.72 1.00 0.63 5.53 0.11 Autodesk Storm and Sanitary Analysis 0.23 0 Calculated LOWFLOW ORIFICE 0 06:00 0.03 0.00 OVERFLOW ORIFICE 0 04:22 0.61 INF_51N/HR OUTLET 0 03:15 0.28 Highest Flow Instability Indexes All links are stable. WARNING 107 : Initial water surface elevation defined for Junction Ji is below junction invert elevation. Assumed initial water surface elevation equal to invert elevation. WARNING 108 : Surcharge elevation defined for Junction Jl is below junction maximum elevation. Assumed surcharge elevation equal to maximum elevation. WARNING 110 : Initial water surface elevation defined for Storage Node SUBSURFACE is below storage node invert elevation. Assumed initial water surface elevation equal to invert elevation. WARNING 110 : Initial water surface elevation defined for Storage Node SURFACE is below storage node invert elevation. Assumed initial water surface elevation equal to invert elevation. Analysis began on: Tue Feb 19 11:25:36 2019 Analysis ended on: Tue Feb 19 11:25:36 2019 Total elapsed time: < 1 sec Autodesk Storm and Sanitary Analysis Maps and References Isopluvial Maps Excerpts from County of San Diego Hydrology Manual 11Page 0 100 30 LU (I) LU LU LL 0 z LU z - LU () U) a Ui U) i LL 1 10 LU LU EXAMPLE: Given: Watercourse Distance (0) = 70 Feet Slope(s)=1.3% T =1.8(11'I Runoff Coefficient (C) = 0.41 3V;. Overland Flow Time (T) = 9.5 Minutes SOURCE: Airport Drainage, Federal Aviation Administration, 1965 Ua20 5 0 F//00,0~0~0,0000 ir FIGURE Rational Formula - Overland Time of Flow Nomograph 34 INS 0.111111111111111111111111111111 IN TION _____________ i '__ 11111111 u.' Intensity (i hr) jjjjj~ I P6 6-Hour Precipitation (in) 11111111 Duration uu.UUlh 91h'Ih th $Ii u ••••••••.u.uu .!IIh1!uIIh'IhIh15IIlIh. 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