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Home My WebLink AboutCDP 2019-0032; LOVE RESIDENCE; HYDROLOGY AND STORM WATER MANAGEMENT REPORT; 2019-11-14- CITY OF CARLSBAD ENGINEERING DIVISION HYDROLOGY AND STORM WATER MANAGEMENT REPORT FOR LOVE RESIDENCE 4615 TELESCOPE AVENUE ENGINEER OF WORK k VINCE~SJ;_1 «-3 - Telescope Ave. PREPARED BY: SAMPO ENGINEERING, INC. 171 SAXONY ROAD, SUITE 213 ENCINITAS, CA 92024 (760) 436-0660 Standard Development Project 1 Sampo Engineering, Inc. 11 /14/2019 Introduction: The subject property is approximately 0.18 gross acres and is located on the westerly side of Telescope A venue, in the City of Carlsbad. The property is currently a vacant lot. The property currently sheet flows on the surface at an approximately eight percent slope from the rear of the property to the curb and gutter on Telescope A venue near the northeast comer of the property. The owner proposes to construct a new single family residence with an attached garage, impermeable paver flatwork, landscaping and retaining walls and other associated improvements. The area of proposed soil disturbance is 6,192 square feet. The project proposes an increase in impervious surface areas, which will result in an increase in runoff. The increase will be mitigated as described in the storm water quality summary below. This project proposes to maintain the historical drainage pattern where runoff generated onsite flows offsite from the rear of the property to the curb and gutter on Telescope A venue. Run-on from off-site west and north neighboring properties will be collected in a brow ditch and conveyed through vegetated swales along the side yards to Telescope Ave. Hydrology Summary: A hydrology study utilizing the Rational Method was perfonned for the existing and proposed conditions within the area of proposed disturbance, and the results are as follows. The existing condition is calculated to have a runoff coefficient of C=0.28 and an anticipated runoff for the 100 year storm of Q=0.28 CFS. The Proposed Drainage Basin is composed of one hydrologic basin that is limited to the area of work and produces a runoff coefficient of C=0.54 and an anticipated runoff for the 100-year storm of Q=0.67 CFS. The project proposes an increase in impervious surfaces of 3,208 SF. Storm Water Quality Summary: The project has been determined to be a "Standard Development Project" using the City of Carlsbad Storm Water Standards Questionnaire (E-34) and is therefore exempt from priority project and hydromodification requirements. The development proposes to reduce the discharge of pollutants offsite by utilizing Source Control and Low Impact Development (LID) BMP's to the maximum extent practical. Landscaping and ground cover will be used in yard areas to prevent erosion of the surface of the soil and slopes. Impervious hardscape have been designed to disperse runoff away from structures to landscape areas before being collected in a private storm drain system. Storm water runoff will be conveyed to a proposed rip-rap energy dissipator before entering a vegetated swale system located around the property to satisfy storm water quality standards for treatment before discharging to the westerly side of Telescope Avenue. Telescope Ave. Standard Development Project 2 Sampo Engineering, Inc. 11/14/2019 IMPERVIOUS AREA CALCULATIONS DMA-1 EXISTING •• Impervious Areas per Layer: V-CALCS-IMPV-COLR DESCRIPTION CONCPATH SHED L PROPOSED IMPERVIOUS (SF) 218.00 83.00 301.00 •• Impervious Areas per Layer V-CALCS-IMPV-COLR DESCRIPTION REMOVE & BLDG (R&R) REPLACE NEW BLDG CONC L PROPOSED tJ. t. IMPERVIOUS (SF) : IMPERVIOUS SF 131.00 2658.00 720.00 3509.00 3208.00 JN: 19-110 INITIALS: IQ DATE: November 14, 2019 Note: Areas from AutoCAD .. Pervious Areas per Layer: V-CALCS-PERV-COLR DESCRIPTION PERVIOUS (SF) TOTAL (SF) PERVIOUS 7564.00 + 7564.00 7865.00 .. Pervious Areas per Layer: C-CALCS-PERV-COLR DESCRIPTION PERVIOUS (SF) TOTAL (SF) PERVIOUS 4356.00 + I:: 4356.00 7865.00 t. PERVIOUS (SF) : -3208.00 171 Saxony Road, Suite 213 • Encinitas. CA 92024 • P: 760-436-0660 • F: 760-436-0659 • info@sampoengineering.com DRAINAGE STUDY CALCULATOR EXISTING DRAINAGE BASIN #1 JN: 19-110 INITIALS: IQ DATE: November 14, 2019 DESCRIPTION: Area = 7,865 SF 0.18 AC ~ = (0.90)(%Impervious) + (Cp)(1-%lmpervious) (0.04 %)(0.9) + (0.96 %)(0.25) 0.28 12 = 104.05 ( Watercourse Distance, FT) ~ = 79 (Slope,%) I c1 = 1.8(1.1-C)(D)112 1.8(1.1-0.35)(104.051'112 6.91 MIN (S)'/3 (7.9)•113 e. 2 = 1.3 ( 2-Year, 6-Hour lsopluvial) f 10 = 1.7 ( 10-Year, 6-Hour lsopluvial) f.100 = 2.6 ( 100-Year, 6-Hour lsopluvial) !z = 7.44 P2 Dre, -0645 7. 44(1. 3)(6.91 )'(-0.645) 2.78 IN/HR !10 = 7.44 P,o Dre, -0645 7.44(1. 7)(6.91)'(-0.645) 3.64 IN/HR l 100 = 7.44 P,oo Dre, -0&45 7.44(2.6)(6,91)•(-0.645) 5.56 IN/HR 9.2 = CIA (0.28)(2. 78 INIHR)(0.18 AC) 0.14 CFS 9.10 = CIA (0.28)(3.64 INIHR)(0.18 AC) 0.18 CFS Q_ 100 = CIA (0.28)(5.56 INIHR)(O. 18 AC) 0.28 CFS Per San Diego County Hydrology Manual 2003 171 Saxony Road, Suite 213 • Encinitas, CA 92024 • P: 760-436-0660 • F: 760-436--0659 • info@sampoengineering.com DRAINAGE STUDY CALCULATOR PROPOSED DRAINAGE BASIN #1 JN: 19-110 INITIALS: IQ DATE: November 14, 2019 DESCRIPTION: Area = 7,865 SF 0.18 AC ~ = (O.90X0/olmpervious) + (CPX1-%Impervious) (O.45 %XO.9) + (O.55 o/oXO.25) 0.54 l2. = 56.2 ( Watercourse Distance, FT) ~ = 18.8 (Slope,%) I c1 = 1.8(1.1 -C)!D)"2 1.8(1.1-0.69l(56.2t112 = 2.08 MIN (S)'/3 (18.8)•113 Ic2 = 110.38 FT X 1 MIN 0.86 MIN 2 FTIS 60SEG r 2.94 MIN Tcr011I =2.94 MIN < 5 MIN USE 5.00 MIN e.2 = 1.3 ( 2-Year, 6-Hour lsopluvial) e 10 = 1 7 ( 10-Year, 6-Hour lsop/uvial) P.100 = 2.6 ( 100-Year, 6-Hour lsopluvial) !2 = 7.44 P2 Dr., --06<5 7. 44(1. 3)(5)'(-0. 645) 3.43 IN/HR f 10 = --06<5 7.44 P10 Dr.1 7.44(1. 7)(5)•(-0. 645) 4.48 IN/HR l 100 = 7.44 P 100 Drc1 --06<5 7. 44(2. 6)(5)•(-0. 645) 6.85 IN/HR 92 = CIA (0.54)(3.43 INIHR)(O. 18 AC) 0.33 CFS 910 = CIA = (0.54)(4.48 INIHR)(0.18 AC) 0.44 CFS 9100 = C I A (0.54)(6.85 INIHR)(0.18 AC) 0.67 CFS Per San Diego County Hydrology Manual 2003 171 Saxony Road, Suite 213 • Encinitas, CA 92024 • P: 760-436-0660 • F: 760-436-0659 • info@sampoengineering.com Jo5 ~ < ~ ~ ,I-· ~,~Th~ / ~ Vt)~ 2 '\ -~~ I I I _J~~@I~ ');§ ~' '."S?)'J~\ J ff1 I I I I I I I DRAINAGE MAP I I I I I I I I 4615 TELESCOPE AVENUE EXISTING CONDITION I , I I 1/287.67 287.20 TC -. I /~ . .,10·f': 281.13 FL ;:,-/ Al -_ 2s1.e ~ --I I '8 --TC '88.~FL '88 ~TC S;: 28875 ""' ?.92Je r.55 FL (37 TC ~vv. I I ~, ~ s:::s .::?i "ff. 289.8L ~ 289.61 20 10 0 20 40 4 -2s113:¼..J • ;;, ,,-...J -pJ'>'°'"~~~·-~ ~~~~,-\Fi~ jJ 289.78 ·: J ii ;\ ( f_, 289.35 Fl I I ~ I I )< 289.58 I SCALE: 1" = 20' ;h,,=-!--,,_ JN: 19-110 11.14.19 •.t" ---:~SAMP □ ,._-~~'S<'-'c·,-:-)~i: NGIN EE RING, INC. ~• ~-I • . I ... ~ 171 SAXCWY ROAIJ, SUITE 213, ENCJNITAS. CA 92024 TEL: {760} 4J6-~ ol -..,,J 4J6-0659 .Jo5 0.5: ~ ( ~ ~ C } _]jw1~1i '>;§ )' '."$1).)-J'v\ ;. )\)\l 29.8.9 0.18 AC 0.54 -6.85 IN, t."j• o · . t.~-::~.) __ .....--/ . ~ ~ r}; 'v ~ I I I I / / DRAINAGE MAP / // 4615 TELESCOPE AVENUE 1 e '1?81.N 281.13 Fl I iY ,..4 I (, 1883 TC j '8 ~--· '88:!~; f ~ 2887: S;: // ~ ~ ':'[ '9.37 TC 2, G ~ 20 40 , JIJ-U J~:1yy:,,~ . ~31 --. I ~ "'1Eef'i~ 1 ~BR,Qt.,~~ '89.82 S:::S '89.33 ~ .P--,.,,cn»::r:;~ ~, ~ ':,:)-l-:-,i'<'--i'-1'-J_"('..,j 4 'I [;::J Jj\\ (! ·M~~; SCALE: 1" = 20' I I I I I I I I JI > 289.58 -~,J.... JN:19-110 11.14.19 [(~-,~~-~AMP □ ,\-,_. I ~•g -~s6 .~ .. }ik NGIN EE RING, INC. ·-r~ ~ 171 SAX(l{Y ROA/J, SIJTf 21J,FClfflTAS. CA 92024 TEL: (760) 436-0660 F{ ~) 436-0659