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Home My WebLink AboutSDP 15-04; AVENIDA ENCINAS PARKING EXPANSION; HYDRAULICS ANALYSIS; 2015-10-01HYDRAULICS ANALYSIS 5999 AVENIDA ENCINAS, CARLSBAD, CA PARKING EXPANSION HOWES, WElLER & ASSOCIATES 2888 LOKER AVENUE EAST, CARLSBAD, CA RECR, y V707-11) (760) 929-2288 ) DEC Ii 2015 PREPARED BY WALTER H. Brown, P.E. C-36191 ON October 1, 2015 Ut 9E: H. ';,' C 36191 S &3W16 I Consists of 12 pages 5W lSO1 LINCOLN/AE Rational Methood Hydrology Runoff from existing turfed area (Area 'A' to Ditch Drain at point 'Z') Prepared By: W Brown Date:10/10/15 Descriptions Values tion N 33.123028 pHydrologic W 117.325047 r SCS Atlas Huerhuero roup D Severe Return Period or 85th Percentile 85th Storm Length p6 lsohyet Value (from lsohyetal Maps) = 0.63 Land Use Turf Runoff Coefficient = C (from Table 3-1 San Diego County Hydrology Manual) = 0.35 rea in Acres = 0.1024 verage Slope = s = 0.11 Length of Run = d (in feet) = 178.10 Initial Time (minutes) = T = 5.00 lime of Travel = Tt = (1.1-c)d°5 /s°333 = 20.76 lime of Concentration = Tc = Ti + Tt = 25.76 Intensity = I = 7.44 P6 D-0.645 = 0.58 Flow Quantity = Q = CIA (in cfs) = 0.021 Page 2 of 12 LINCOLN/AE Rational Methood Hydrology Runoff from existing turfed area (Area 'B' to Ditch Drain) Prepared By: W Brown Date:10/10/15 Descriptions Values tion N 33.123028 rHydrologic W 117.325047 r SCS Atlas Huerhuero roup D Severe Return Period or 85th Percentile 85th Storm Length P6 lsohyet Value (from lsohyetal Maps) = 0.63 Land Use Turf Runoff Coefficient = C (from Table 3-1 San Diego County Hydrology Manual) = 0.35 rea in Acres = 0.0637 verage Slope = s = 0.050 Length of Run = d (in feet) = 98.80 Initial Time (minutes) = T = 5.00 lime of Travel = Tt = (1.1-c)d°5 /s°33 = 20.29 lime of Concentration = T = Ti + Tt = 25.29 Intensity = I = 7.44 P6 D-0.645 = 0.58 Fl ow Quantity = Q = CIA (in cfs) = 0.013 Page 3 of 12 LINCOLN/AE Rational Methood Hydrology Runoff from existing turfed area (Area 'C' to Ditch Drain) Prepared By: W Brown Date:10/10/15 Descriptions Values tion N 33.123028 pHydrologic W 117.325047 r SCS Atlas Huerhuero roup D Severe Return Period or 85th Percentile 85th Storm Length p6 lsohyet Value (from lsohyetal Maps) = 0.63 Land Use Turf Runoff Coefficient = C (from Table 3-1 San Diego County Hydrology Manual) = 0.35 rea in Acres = 0.0315 verage Slope = S = 0.050 Length of Run = d (in feet) = 92.95 Initial Time (minutes) = T = 5.00 lime of Travel = Tt = (1.1-c)d°5 /s°333 = 19.68 lime of Concentration = T = Ti + Tt = 24.68 Intensity = I = 7.44 P6 D-0.645 = 0.59 Flow Quantity = Q = CIA (in cfs) = 0.007 Page 4 of 12 UNCOLN/AE Rational Methood Hydrology Runoff from existing turfed area (Area 'D' to Sub- Drain at point 'V') Prepared By: W Brown Date:10/10/15 Descriptions Values tion N 33.123028 pHydrologic W 117.325047 r SCS Atlas Huerhuero roup D Severe Return Period or 85th Percentile 85th Storm Length p6 Isohyet Value (from lsohyetal Maps) = 0.63 Land Use Porous AC Runoff Coefficient = C (from Table 3-1 San Diego County Hydrology Manual) = 0.35 rea in Acres = 0.0147 verage Slope = s = 0.008 Length of Run = d (in feet) = 166.50 Initial Time (minutes) = T = 5.00 time of Travel = Tt = (1.1-c)d°5 O.333 = 4934 flme of Concentration = T = Ti + Tt = 54.34 Intensity = I = 7.44 P6 D-0.645 = 0.36 Flow Quantity = Q = CIA (in cfs) = 0.002 Flow quantity assumes worst cases; asphalt surface completely clogged or design storm is following a storm that filled the pavement pores and the voids in the aggregate storage. Page 5 of 12 LINCOLN/AE Rational Methood Hydrology Runoff from existing turfed area Pre-Development Prepared By: W Brown Date:10/10/15 Descriptions Values tion N 33.123028 rHydrologic W 117.325047 r SCS Atlas Huerhuero roup D Severe Return Period or 85th Percentile 85th Storm Length P6 lsohyet Value (from lsohyetal Maps) = 0.63 Land Use Turf Runoff Coefficient = C (from Table 3-1 San Diego County Hydrology Manual) = 0.35 Area in Acres = 0.2122 Average Slope =s= 0.069 Length of Run = d (in feet) = 267.40 Initial Time (minutes) = T1= 5.00 flme of Travel = Tt = (1.1-c)d°5 /s°333 = 29.87 flme of Concentration = Tc = Ti + Tt = 34.87 Intensity = I = 7.44 P6 D-0.645 = 0.47 Flow Quantity = Q = CIA (in cfs) = 0.035 Flow quantity assumes worst cases; asphalt surface completely clogged or design storm is following a storm that filled the pavement pores and the voids in the Sum of Flows to Point 'X' pre-Development (in cfs) = 0.0350 Sum of Flows to Point 'X' post-Development (in cfs) = 0.0430 Rational Method: Runoff Volume For designs that are dependent on the total storm volume, a hydrograph must be VOL= CP6A Where: VOL = volume of runoff (acres-inches) Pa = 6-hour rainfall (inches) C = runoff coefficient A = area of the watershed (acres) For designs where the criteria is to assure no net increase in instantaneous flow and no net increase of flow during the storm design period (P6) required storage may be calculated as VOL =((Q-)/Q9 )CP6A Page 6 of 12 Where: Q,, = Q = CIA for the build-out condition and Q = Q = CIA for the pre-development condition Required Storage (in ft) = ((Q -)/Q)CP6A = 29.22 Voids ratio for l crushed rock per 200-1.2 SSPWC is nominally 30% when compacted to 90% relative density, 110 pcf Cubic feet of crushed rock to provide 29.22 ft3 voids = 97.42 Cubic feet of crushed rockprovided in design = 2010.00 Page 7 of 12