The URL can be used to link to this page

Home My WebLink AboutPD 2019-0009; WEBSTER RESIDENCE; LIMITED DRAINAGE STUDY;ENGINEERING 2121 Montiel Road, San Marcos, CA 92069 0 DESIGN GROUP 760.839.7302 www.designgroupca.com LIMITED DRAINAGE STUDY WEBSTER RESIDENCE APN 215-460-05 Argonauta Street Carlsbad, California 11 Prepared By: V Erin Rist MAR 231 219 RCE 65122 LAND DEVELO .. EGNEER 1oO(Jo1 PROJECT DESCRIPTION The subject property is described as APN 215-460-05 and is located at Argonauta Street near the intersection with Obelisco Circle, Carlsbad, California. The property is approximately 0.75 acres and is currently undeveloped. Portions of the lot were previously graded. In general, the property slopes, descending from the south (front) to the north (rear). PROJECT SCOPE The proposed new scope of work consists of the construction of a new multi-level single family residence and associated driveways and landscape elements. BASIN DESCRIPTION AND FLOW PATTERNS The subject site has been divided into two primary Basins, as more specifically described below. Basin Hi: Basin Hi includes the area of proposed development. Basin H2: Basin H2 Includes existing unimproved sloped areas that will remain in the existing condition post development. Pre-development flow consists of sheet flow across the undeveloped site. An existing concrete brow ditch runs along a 10 ft. wide drainage easement, from east to west, along the north property line. Sheet flow runoff is captured by the existing brow ditch. In the post development condition runoff will be directed from roof downspouts to landscape areas, where possible, and new catch basin inlets. New private storm drain system will direct water to a new onsite retention basin for containment of increased flows as part of onsite development. Sizing of retention area is included in the attached hydrology and hydraulic calculations. Retention basin overflow outfall will be by pipe to a gravel subsurface disbursement trench, so as not to concentrate runoff. 0 WEBSTER RESIDENCE Argonauta Street, Carlsbad PRELIMINARY HYDROLOGY CALCULATIONS C(composite) C=0.90 x % impervious surfaces + Cp x (1-%impervious) RATIONAL METHOD FOR TRIBUTARY < 0.5 SQ MILE CIA I(in/hr) - 100 YR 7.40 7.44 P6 DA(0.645) P6 2.8 I(in/hr) - 50 YR 6.59 =7.44 P6 DA(0.645) P6 2.50 SOILTYPE D HYDROLOGIC & HYDRAULIC DESIGN BASIN NO. TOTAL AREA (sf) TOTAL AREA (ac) IMPERV AREA (sf) AREA IMPERV % IMP AREA PERV (sf) AREA PERV (ac) C T Q100 (cfs) (ac) Drainage Device Elev 1 (ft) Elev 2 (ft) Length (ft) Slope (ft) Add'l Q Drainage Device Size V (ft3)= P6 50*A*C PRE-DEVELOPMENT ONSITE Hi 15,110 0.35 - 0.00 0.00 15,110 0.35 0.35 5 0.90 1,102 H2 17,445 0.40 - 0.00 0.00 17,445 0.40 0.35 5 1.04 32,555 TOTAL 1.94 POST DEVELOPMENT ONSITE H1A 4,105 0.09 4,105 0.09 1.00 - 0.00 0.90 5 0.63 Impervious - Pipe to bioretention Pervious - Sheetfiow 504.0 483.5 67.0 0.31 61n 770 H1B 4,145 0.10 4,075 0.09 0.98 70 0.00 0.89 5 0.63 Downspouts divided to H1C, HiD, H1A, Various 769 H1C 1,820 0.04 - 0.00 0.00 1,820 0.04 0.35 5 0.11 Roof Gutters to Landscape to Pipe 513.6 504.8 30.0 0.29 61n 133 HiD 745 0.02 - 0.00 0.00 745 0.02 0.35 5 0.04 Roof Gutters to Landscape to Pipe 514.9 514.9 65.0 0.00 61n 54 H1E 1,460 0.03 - 0.00 0.00 1,460 0.03 0.35 5 0.09 Sheet flow 6 in 106 H1F 2,345 0.05 120 0.00 0.05 2,225 0.05 0.38 5 0.15 Downspoutrto Pipe 493.4 483.5 74.0 0.13 6 in 185 14,620 Subtotal Q 1.64 2,017 delta Q 0.75 H2 18,035 0.41 - 0.00 0.00 18,035 0.41 0.35 5 1.07 Sheetfiow 8,300 TOTAL 2.72 32,655 0.75 DETENTION VOLUME Area Vpost-Vpre - Required (cf) Area (sf) _________ Depth (ft) _________ Provided (cf) Hi 915 1 1,035 1.10 1,139 * Provided Area - Area * Depth of Base * 0.4 WO HYDROLOGY PRE- DEVELOPMENT DRAINAGE SUMMARY TABLE Basin Area (ac) Impervious Area (ac) Q (cfs) Hi 0.35 0 0.90 H2 0.40 0 1.04 - - - - PROJECT BOUNDARY HYDROLOGY SUB—BASIN FLOW DIRECTION HYDROLOGY POST-DEVELOPMENT DRAINAGE SUMMARY TABLE Basin Area (ac) Impervious Area (ac) Q (cfs) H1A 0.09 0.09 0.63 H1B 0.09 0.09 0.63 H1C 0.04 0 0.11 HiD 0.02 0 0.04 HIE 0.03 0 0.09 H1F 0.05 0.01 0.15 H2 0.41 0 1.07 - - - - PROJECT BOUNDARY FLOW DIRECTION I I HYDROLOGY BASIN PRP. BLDG SURFACE—IMPERVIOUS PRP. CONC/AC PAVING (E) AC PAVING fl HYDROLOGY S S 0 33d04'07.67"; 117d0538.30" County of San Diego Orange ____ _______ ________ ________ Hydrology Manual nty33•3-_--i- ___ 33 W /_ - & Riverside County :N\ ir - RafdlIsopla 33*15, 100 Year Rfafl Event 6Hou - - -o - --..-- ---. -- -------- - a3 ,-• 0 jr I: P-- -- --.- KI, I'. .40 T . - ShE 1 :j::2c$:;; DPW L •:.: MeX%C I __ 32'W 32*W 3 0 3MB.. County of San Diego Hydrology Manual County L. Riverside County Rain all Isopluvials iT I Year Event 24 fl ors - cçbJrC1) C5---s_uEft_ LN . / tV I".. •- j rr : ..... .. j. .•— ... ./ - SITE DPW _ is SGIS MexC 0 __ County of San Diego 33 Orange 3O - ---J-.- — ____________ 33-0 Hydrology Manual .A)UflLy . _____________________ ______________________ _____________________ Riverside County V ----- RainfaiIsopluviaL - 33*15'• . -. . s... 3319 O Yew RnfaH Event -6Hours d i — . . -. . 6... .• ( Isou nches) cjwaAw -------- . I EII - (...........:. 1 - ,.- . . ____ : - . • - . . ,4... -•.. -. - - • •. - ........ • :-. • ••'N. I --------------- / 324 rA 4- t- - .- .. - - -. . \ -- '. 10 . 5 ITE SZn GIS - M e x I C ) N B _______ 3230 y s 3 0 3M11.. County of San Diego Orange - Hydrology Manual 33 County - -•.... ....:• I / - Riverside County I- -45 . I) S Ira .. N e .-. Rainfall 1sopluvuiL .. - • I • ••••\••• . ..-, •. . '.-.. .....95 -33 5O Year Raall Event 24Hours - •. .-.-... • • . - CI e) .....• .• :;.° .................-. 1 ) - ' 70 ITE DPW 4~GIS Sion : M 1 Legend County of San Diego Orange -- - Hydrology Manual - V County - - ...VVV• --____ - V V Soil Hydrologic Groups WIT Legend ocwr,c V I Soil Groups - I / pA Group B upC V __________ V Date Lk~bl. .-- o V - V o o w V V V o V I, VV _VV -- - DPW V V $'S a M ____ __ --.- - __________________ ___________ - 303M11 SITE S . . San Diego County Hydrology Manual Section: 3 Date: June 2003 Page: 6 of 26 Table 3-1 RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use I Runoff Coefficient "C" Soil Type Elements I % RAPER A B C D 0 10 20 25 30 40 45 50 65 80 80 85 90 90 95 NRCS Elements Undisturbed Natural Terrain (Natural) Low Density Residential (LDR) Low Density Residential (LDR) Medium Density Residential (MDR) Medium Density Residential (MDR) Medium Density Residential (MOR) Medium Density Residential (MDR) High Density Residential (HDR) High Density Residential (HDR) Commercial/Industrial (N. Corn) Commercial/Industrial (G. Corn) Commercial/Industrial (OP. Corn) Commercial/Industrial (Limited I.) Commercial/Industrial (General I.) Permanent Open Space Residential, 1.0 DU/A or less Residential, 2.0 DU/A or less Residential, 2.9 DUIA or less Residential, 4.3 DU/A or less Residential, 7.3 DU/A or less Residential, 10.9 DU/A or less Residential, 14.5 DU/A or less Residential, 24.0 DU/A or less Residential, 43.0 DU/A or less Neighborhood Commercial General Commercial Office Professional/Commercial Limited Industrial General Industrial 0.20 0.25 0.30 0.35 0.27 0.32 0.36 0.41 0.34 0.38 0.42 0.38 0.41 0.45 0.41 0.45 0.48 0.48 0.51 0.54 0.52 0.54 0.57 0.55 0.58 0.60 0.66 0.67 0.69 0.76 0.77 0.78 0.76 0.77 0.78 0.80 0.80 0.81 0.83 0.84 0.84 0.83 0.84 0.84 0.87 0.87 0.87 0.49 0.52 0.57 0.60 0.63 0.71 0.79 0.79 0.82 0.85 0.85 0.87 *The values associated with 0% impervious may be used for direct calculation of the runoff coefficient as described in Section 3.1.2 (representing the pervious runoff coefficient, Cp, for the soil type), or for areas that will remain undisturbed in perpetuity. Justification must be given that the area will remain natural forever (e.g., the area is located in Cleveland National Forest). DU/A = dwelling units per acre NRCS = National Resources Conservation Service 3-6 Nomograph for Determination of Time of Concentration (Tc) or Travel Time (TI) for Natural Watersheds 3.4 HYDRAULICS 0 HYDRAULIC DESIGN PIPES Label Solve For Friction Method Roughness Coefficient Channel Slope (ft/ft) Normal Depth (in) Diameter (in) Discharge (ft31s) Flow Area (ft2) Wetted Perimeter (ft) Hydraulic Radius (in) Top Width (ft) Critical Depth (ft) Percent Full (%) Critical Slope (ft/ft) Velocity (ft/s) Velocity Head (ft) Specific Energy (ft) Froude Number Maximum Discharge (ft3/5) Discharge Full (ft3/s) Slope Full (ft/ft) Flow Type HiD to H1C Normal Depth Manning 0.01 0.02 0.4 6.0 0.10 0.17 1.13 0.15 0.38 0.16 82 0.00 0.6 0.01 0.42 0.16 0.11 0.1 0.00 SubCritical H1C1 to H1C2 Normal Depth Manning 0.01 0.32 0.45 6 0.44 0.19 1.25 0.15 0.3 0.34 90.1 0.01 2.36 0.09 0.54 0.53 0.44 0.41 0.00 SubCritical H1C2 to H1A Normal Depth Manning 0.01 0.32 0.5 6.0 0.44 0.19 1.25 0.15 0.3 0.34 90.1 0.01 2.4 0.09 0.54 0.53 0.44 0.41 0.00 SubCritical H1F1 to H1F2 Full Flow Manning 0,01 0.15 0.5 6.0 0.28 0.2 1.57 0.13 0 0.27 100 0.00 1.4 0.03 0.53 0 0.3 0.28 0.00 SubCritical H11`2 to Outfall Full Flow Manning 0.01 0.13 0.5 6.0 0.26 0.2 1.57 0.13 0 0.26 100 0.00 1.3 0.03 0.53 0 0.28 0.26 0.00 SubCritical Label Solve For Friction Method Pressure at 1 (psi) Pressure at 2 (psi) Elevation at 1 (ft) Elevation at 2 (ft) Length (ft) Roughness Coefficient Diameter (in) Discharge (ft3/s) Energy Grade at 1 (ft) Energy Grade at 2 (ft) Hydraulic Grade at 1 (ft) Hydraulic Grade at 2 (ft) Flow Area (ft') Wetted Perimeter (ft) Velocity (ft/s) Velocity Head (ft) Friction Slope (%) Notes Messages SuperCritical H1A to Outfall - Elevation at 1 Manning 0 0 485.0 1 483.5 67.00 0.01 6 1.1 485.51 483.99 1 485.02 1 483.50 0.2 1.57 5.6 0.49 2.27434 SuperCritical 0