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Home My WebLink AboutMS 04-06; MAY MINOR SUBDIVISION; DRAINAGE REPORT; 2019-11-20DRAINAGE REPORT FOR MAY PANHANDLE AND JOINT ACCESS ROAD 3817 EL CAMINO REAL, CARLSBAD APN 167-080-36 MSO4-06 RECEIVED NOV 21 2019 LAND DEVELOPMENT PREPARED FOR ENGINEERING Mary May 5258 Silkwood Drive Oceanside, CA 92056 UCORD COPY PREPARED BY -- Robert 0. Sukup I Pate 4322 Sea Bright Place 0ESS Carlsbad, CA 92008 t uç.CC November 20, 2019 The subject property is a vacant lot on the west side of El Camino Real, about 500 feet south of Chestnut. There are existing single family homes to the west and south of the lot. The existing lot does have quite a bit of slope to it. It slopes from west to east and has a vertical difference of about 60'. The lot has been approved for 2 lots per MS 04-06. The project has initial conditions to provide for a pan handle driveway and to construct a joint access private road along its eastern boundary to provide access for future development to the north. The final Parcel Map for the property and the Grading Plan for the pan handle driveway and joint access road are being submitted simultaneously. Since the project was approved, the City has completed the widening of El Camino Real which parallels its eastern boundary. The widened roadway does not allow any drainage from the proposed site as well as the 2 lots to the south to flow directly onto El Camino Real. The drainage flows southerly along the existing private frontage road to an existing inlet that connects to the City drainage system. At this time no houses are proposed to be built on the property. Houses will be built by others in the future. Based on the preliminary house designs on the Tentative Parcel Map I have projected the anticipated impervious areas for the new parcels. The 2 lots to the south have driveways and structures and I have allowed for their impervious areas as well. Per my attached Hydrology calculations and nomogram, the existing storm drain inlet does calculate out to work fine. There is an existing AC spillway about 25 feet south of the inlet that connects to an open concrete drainage swale. Both were constructed with the El Camino Real widening. If any blockage were to occur at the inlet, the water would flow to the spillway and enter the City Drainage system. . . The existing drainage inlet is far lower in elevation than any of the existing or proposed homes thus eliminating any potential flooding issues. The proposed project should not create any downstream flooding, erosion, or siltation. MAY 14'/ DROLOCY CALCS ~501 T/P C, Zm A1TAC14&? COUNTY Y OLO&)C. MAP . L-M 33Qo!)!-43 L-' Ir,O SIi P4NNM6 AREA 3,ZCO tER'1O AREA - PtA'./ Lc$r: FuTJe tOOS zzc ei z NwAYs HJ. FO -1 of 11 PAA1OLz 1))\v6)AY rvW WiR.OAOWAv (AT TO-T DRIvEwAy t (-1ao 2C4Oc 1 Z4 * MOs1 OU1 4eJJ4 LZYT 7z 5A',' (65606 FOKflAE i(o> ZG' 1PL I 4PN I OJ5 AA 27 ZZQ 4) 7410, ' Ek.vl OOs oc a - c eotErnJrIou. THTLLt4GT 4J,MiN T -' r+ Mi. I - Qc CIA= ,ED c4.,yi.I •.a)G ALL RAII'1AE- FWWS TO A Q Y " OPEj.jiJG• PV-74 A-r1AGb CAPACITY NOMOA& 4 A tu,v- CAPACI%TY 51c:F 9.4 > 43: OK ZZTeF D a F a 4iic DQE ' 7e 0 ter 1vv CgC JMtE LeE C Cb0 - +mic LeE 5 DaE2 MC CD \ I E Cc 0 A i 6 ST U A M C -- - - CARLSBAD ,- J So C CD CbD eC LQ <\,.j 0 7 LvF3 (S - C LeC L AD e C b L eE3 o A Md MIE 7 C LfC AdC/e HedioncL C) 0 i.,tII GaE 0 C bE C LeE cr A MIC 01DB MIC 's'tG LeE-2 LeE2 FEET g .4W. Joins .s4e.t 1) COUNTY YOgCIC Soils Interpretation Study SOIL GR)Ps ft7- —d I I!flflhlflC — iannII Onthn iI San Diego County Hydrology Manual Section: 3 Date: June 2003 Page: 6 of 26 Table 3-1 RUNOFF COEFFICIENTS FOR URBAN AREAS Runoff Coefficient "C" Undistwbed Natural Terrain (Natural) Low Density Residential (LDR) Low Density Residential (LDR) Low Density Residential (LDR) Medium Density Residential (MDR) Medium Density Residential (MDR) Medium Density Residential (MDR). Medium Density Residential (MDR) High Density Residential(HDR) High Density Residential (lDR) Commercial/Industrial (N. Corn) Commercial/Industrial (G. Corn) Commcrciai/Industzial (O.P. Corn) Commercial/Industrial (Limited I.) Permanent Open Space Residential, 1.0 DU/A or less Residential, 2.0 DU/A or less Residential, 2.9 DU/A 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 0.20 0.27 0.34 0.38 0.41 0.48 0.52 0.55 0.66 0.76 0.76 0.80 0.83 - 0.83 0* 10 20 25 40 45 50 65 80 80 85 90 90 0.25 0.30 0.35 0.32 .0.36 0.41 0.38 0.42 0.46 0.41 0.45 0.49 045 0.52 0.51 0.54 0.57 0.54 0.57 0.60 0.58 0.60 Or 63 0.67 0.69 0.71 0.77 038 0.79 0.77 0.78 0.79 .0.80 0.81 0.82 0.84 0.84 0.85' 0.84 0.84 0.85 *The values associated with 0% Impervious may be used for direct calculation of the runoff coefficient as described in Section 3.12 (representing the pervious runoff coefficient, Cp, for the soil type), or for areas that will remain undistñrhed in perpetuity. 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