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Home My WebLink AboutMS 01-13; CARRILLO CANYON VIEWS; PRELIMINARY DRAINAGE STUDY; 2001-07-17PRELIMINARY DRAINAGE STUDY FOR CARRI.LL.O CANYON VIEWS (TENTATIVE MAP NO. CT -) CITY OF CARLSBAD CIVCOM&ASSOCIATES CONSULTING ENGINEERS • PLANNERS O/3 PRELIMINARY DRAINAGE STUDY FOR CARRILLO CANYON VIEWS CITY OF CARLSBAD ckOF ESS,9,' JULY 171 2001 CO Job No. 1254 Uj NO. 51348 Exp: 631002 ) CIVIL 0 @ OF CA0& R. BHATIA, M.S. R.C.E. #051348 Exp. 6 - 30 - 02 Prepared By: CIVCOM & ASSOCIATES 3665 RUFFIN ROAD, Suite 230, San Diego, California 92123 Phone: (619) 505 - 6800 Fax: (619) 505-8866 1254DS.PM5 vi:c • —.,'•. i.$: - - .'.. - TABLE OF CONTENTS Page Introduction I Vicinity Map 2 Hydrology Methodology 3 Hydrology Results 5 Hydraulic Methodology 9 References 10 Appendices Maps Offsite Hydrology Map - Existing Condition 100-year, six hour strom event Onsite Hydrology Map - Existing Condition 100-year, six hour strom event Onsite Hydrology Map - Proposed Condition 100-year, six hour strom event .rr INTRODUCTION This report presents a preliminary drainage study for the Carrillo Canyon Views. The area is located north of Unicornio Street and west of El Fuerte Street in the City of Carlsbad (see Vicinity Map). This drainage study includes a Hydrology Study for the basin 100. (see Hydrology Maps) The basin 100 is located along the north side of Unicornio Street. In the pre-development condition, this basin consists of approximately 0.42+ acres which currently contributes storm runoff to a B-2 inlet in the Unicornio Street at station 55 + 76+ which has been sized to receive this flow. SE q7 \\ JP1 / / II- d 0 LN. \ S BLACK RAIL COURT BATIQUITOS LAGOON AE V I C I NI TY MAR NOT TO SCALE OM AR ;-~~O R TRD. EL FUERTE ST. \ SITE \, ALGA RD. Hydrology Methodology for Onsite The rational method (Q=CIA) is used to determine the onsite runoff. Runoff coefficient, ("C") is: Existing rural area 0.45 Single residential units 0.55 Impervious areas 0.90 A soils group of "D" is assumed. 100 year 6 hour precipitation: - Time of concentration, Appendix "D" is derived from equation Tc=(1 1.9 L3/H).315X 60 minutes. For basins where time of concentration is less than 10 minutes, a minimum value of 10 minutes is used. Travel time in pipes is calculated by equation L I (V*60). Each sub area is calculated individually for time of concentration with longest aggregate time being the total time for the site. Intensity is derived from the equation in Intensity chart. I = 7.44 P6D-645 -3- Confluence Method Let Q, T and I correspond to the tributary with the largest discharge. Let q, t, and i correspond to the tributary with the smallest discharge. Let Q, and T correspond to the discharge and the time of concentration when peak flow occurs. If 1> t, the peak discharge is corrected by the ratio of the intensities: Q=Q+q(lli) and TT. - If T < t, the peak discharge is corrected by the ratio of the times of concentration: Q=Q+q(T/t) and T=T. -4- PROJECT: CARRILLO CANYON VIEWS JOB No.: 1254 SHEET 1 OF 1 7/19/01 It'I1L?— 'i I!LWJ 1 LUIiTI!i LL!L! MUM OEM I 4e1*1s1 j PRE D EVELOPED CO 'III (.] IkL! L!I!I!i J 1254ds.xls CARRILLO CANYON VIEWS LEGEND TENTATIVE PARCEL MAP NO. MS 01- SUBDIVISION BOUNDARY ---------------- ------------------- CITY OF CARLSBAD LOT BOUNDARY ------------------------ AREA Co. 1OAC NODE NUMBER---------------------------1100 I NO SCALE I I, HYDROLOGY MAP POST DEVELOPMENT CONDITION S. \CIVCO\ 1254 %INT(G-MS\ I254DSCX.OGN CARRILLO CANYON VIEWS TENTATIVE PARCEL MAP NO. MS 01- LEGEND CITY OF CARLSBAD SUBDIVISION BOUNDARY ---------------- LOT BOUNDARY------------------------ AREA -----------------------------------C O.1OA NODE NUMBER---------------------------1100 I I SCALE 4 S.CIVCOMI254 \I I 2540SP0. OGN HYDROLOGY MAP PRE DEVELOPMENT CONDITION -.,. r't ..ç V - CONCLUSION: The existing 24 inch storm drain in Unicornio Street was designed to accepted the pre- development conditions. The post-development condition 100 year storm peak discharge is approximately 1.2 cubic feet per second. Therefore, it is concluded that the post development condition does not adversely affect the existing 24 inch storm drain (see reference plans in the Appendices). -9- '4. :•* •,. APPENDICES RUNOFF COEFFICIENTS (RATIONAL METHOD) DEVELOPED AREAS (URBAN) Land Use Residential: Single Family Multi-Units Mobile Homes Rural (lots greater than 1/2 acre) Commercial 80% Impervious Industrial " 90% Impervious Coefficient, C Soil Group Q .40 .45 .50 .55 .45 .50 .60 (3 .45 .50 .55 .65 .30 .35 .40 .45 70 .75 .80 .85 .80 .85 .90 .95 NOTES: Soil Group maps are available at the offices or the Department of Public Works. 121 Where actual conditions deviate significantly from the tabulated imperviousness values of 80% or 90%. the values given for coefficient C, may be revised by multiplying 80% or 90% by the ratio of actual imperviousness to the tabulated imperviousness. However, in no case shall the final coefficient be less than 0.50. For example: Consider commercial property on D soil group. Actual imperviousness = 50% Tabulated imperviousness = 80% Revised C = 50 x 0.85 = 0.53 80 IV-A-9 APPENDIX IX Updated 4/93 *t• .4 ... 4 P. -' 1/ Af EQ/,QT/OA/ .385 Tc A-we of co,en/i-zho, I Lenq/h of wale.--.shed D,cre,,ce in e/eva//an a/0n9 c//cc/ire s/one line (See 4opendi 1-8) —30DO L - iWi/es ,'è e Hatws J Al,rni/es '9Do 2--120 - 700 - - -oa\ - —500 _IaO —70 - - • —200 2 - - —3D - —/00 - - \ —2000 —30 NOTE = --_-- -' NATURAL WATERSHEDS —8 QFOR ADD TEN MINUTES TO I' .-240 - /00' - 7 COMPUTED TIME OF CON- - 900 -800 —' —saD —Ia —500 — 100 —3 —300 —5 - —200 H z SAN DIEGO COUNTY NOMOGRAPH FOR DETERMINATION DEPARTMENT OF SPECIAL DISTRICT SERVICES OF TIME OF CONCENTRATION (Ic) FOR NATURAL WATERSHEDS DESIGN MANUAL APPROVED DATE APPENDIX X-A V-A-10 Rev. 5/81