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Home My WebLink AboutPD 2021-0001; HAMDARD RESIDENCE; HYDROLOGY STUDY; 2021-11-16Prepared By: La Caruna Way ARC Construction & Engineering, Inc. Dated: 9-21-21 HYDROLOGY STUDY FOR LA CORUNA PLACE CARLSBAD, CALIFORNIA APN 216-160-23 PROJECT ID NO. GRAD 2021-0001 Prepared For: HAMDARD RESIDENCE 2349 Caringa way, Unit 3 Carlsbad, California 92009 September 22, 2021 Revised 11-16-21 Prepared By: La Caruna Way ARC Construction & Engineering, Inc. Dated: 9-21-21 TABLE OF CONTENTS Page Introduction ................................................................................................................................1 Existing Conditions ....................................................................................................................1 Vicinity Map ..............................................................................................................................2 Proposed Improvements.............................................................................................................3 Conclusion .................................................................................................................................3 Rational Method Methodology ..................................................................................................4 Criteria .......................................................................................................................................5 References ..................................................................................................................................5 APPENDICES Appendix A: County of San Diego Design Charts Appendix B: Existing and Proposed Drainage Map Appendix C: Existing Drainage Basin Calculations Appendix D: Proposed Drainage Basing Calculations Appendix E: Pipe calculations for 4-inch and 6-inch Prepared By: La Caruna Way ARC Construction & Engineering, Inc. Dated: 9-21-21 Prepared By: La Caruna Way ARC Construction & Engineering, Inc. 1 Dated: 9-26-21 Introduction This new development proposes to construct a single residential home within a 2 percent and 2:1 slope. The property is currently vacant and is bordered to the north by La Costa Ave, to the east & west by residential homes, to the south by La Coruna Place. Existing Conditions The existing site is vacant with one type “F” catch basin located at the northeast corner of the lot. The property sheet flows from south to north to La Costa Ave. into a curb inlet located on La Costa Street that discharges at the lagoon about quarter mile to the north. The site does not convey any offsite runoff from the neighbor. Prepared By: La Caruna Way ARC Construction & Engineering, Inc. 2 Dated: 9-26-21 Vicinity Map N Prepared By: La Caruna Way ARC Construction & Engineering, Inc. 3 Dated: 9-26-21 Proposed Improvements The property will drain via a graded swale and 6-inch pipe as shown on the grading plans to an existing curb inlet keeping the same sheet flow. The proposed roof drains for the residential home have been designed to discharge to landscaped areas. This will allow the runoff to sheet flow to the proposed landscaping before leaving the site via curb inlet. Additionally, the driveway area has been designed with porous pavement to provide treatment for the proposed runoff. The runoff will then be capture and convey via 6-inch pipes to the existing curb inlet located at La Costa Blvd. EXISTING CONDITIONS NODE 100 Q100=.85 PROPOSED DEVELOPMENT NODE 200 Q100=.98 INCREASE Q100=.13 Conclusion The proposed sheet flow has been redirected slightly to discharge to La Costa Avenue and the peak runoff will increase by 0.13cfs which is negligible. Therefore, it is our opinion that the redirection of the runoff will not impact the neighbors because the overall location of discharge will remain the same. Prepared By: La Caruna Way ARC Construction & Engineering, Inc. 4 Dated: 9-26-21 DECLARATION OF RESPONSIBLE CHARGE I, hereby declare that I am the engineer of work for this project, that I have exercised responsible charge over the design of the project as defined in section 6703 of the Business and Professions Code, and that the design is consistent with current standards. I understand that the check of project drawings and specifications by the County of San Diego is confined to a review only and does not relieve me, as engineer of work, of my responsibilities for project design. _____________________ Date ______________________________ Engineer of work Sergio Salinas RCE 81026, Exp. 9/30/2023 3-29-22 Prepared By: La Caruna Way ARC Construction & Engineering, Inc. 5 Dated: 9-26-21 Rational Method Methodology The County of San Diego’s Drainage Manual requires that the Rational Method be used for hydrologic analysis of a watershed less than 0.5 square-miles. The Rational Method computer program developed by Advanced Engineering Software (AES) was used for this study because it satisfies the County of San Diego’s design criteria. The hydrologic model is developed by creating independent node-link models of each interior drainage basin and linking these sub-models together at confluence points. The program has the capability to perform calculations for 15 hydrologic processes. These processes are assigned code numbers that appear in the results. The code numbers and their significance are as follows: Code 1: Confluence analysis at a node Code 2: Initial subarea analysis Code 3: Pipe flow travel time (computer estimated pipe sizes) Code 4: Pipe flow travel time (user specified pipe size) Code 5: Trapezoidal channel travel time Code 6: Street flow analysis through a subarea Code 7: User specified information at a node Code 8: Addition of the subarea runoff to mainline Code 9: V-Gutter flow through subarea Code 10: Copy mainstream data onto a memory bank Code 11: Confluence a memory bank with the mainstream memory Code 12: Clear a memory bank Code 13: Clear the mainstream memory Code 14: Copy a memory bank onto the mainstream memory Code 15: Hydrologic data bank storage functions Prepared By: La Caruna Way ARC Construction & Engineering, Inc. 6 Dated: 9-26-21 Criteria In order to perform the hydrologic analysis; base information for the study area is required. This information includes the existing drainage facility locations and sizes, existing land uses, flow patterns, drainage basin boundaries, and topographic elevations. Drainage basin boundaries, flow patterns, and topographic elevations were determined from the Drainage Maps which are located in Appendix B. The hydrologic conditions were analyzed in accordance with the County of San Diego’s design criteria as follows: Design Storm: 100-year 6-hour event Runoff Coefficients: “C” Valves varied from 0.55 to 0.95 depending on the land use Soil Type: “B” Rainfall Intensity: County of San Diego Drainage Design Manual References County of San Diego Drainage Design Manual, 2003. Prepared By: La Caruna Way ARC Construction & Engineering, Inc. Dated: 9-26-21 APPENDIX A County of San Diego Design Charts Prepared By: La Caruna Way ARC Construction & Engineering, Inc. Dated: 9-26-21 APPENDIX B Existing and Proposed Drainage Maps LA CORUNA PLACELA COSTA AVEEXISTING CONDITIONS 0 SCALE: 5'10'20' 1"=10' GROUND FLOOR FF = 148.67' GROUND PAD FG = 148.00' GARAGE FLOOR FF = 148.67' GARAGE PAD FG = 148.00'148146144142140138APN 216-160-024 LOT 182 148 136128 130 132 134 148146144142140138136FILLCUT2:1 SLOPE 2:1 SLOPE2:1 SLOPE1282:1 SL O P E LA CORUNA PLACELA COSTA AVEFILL CUT 0 SCALE: 5'10'20' 1"=10' Prepared By: La Caruna Way ARC Construction & Engineering, Inc. Dated: 9-26-21 APPENDIX C Existing Drainage Basin Calculations Prepared By: La Caruna Way ARC Construction & Engineering, Inc. Dated: 9-26-21 APPENDIX E Pipe calculations for 4-inch and 6-inch