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Home My WebLink AboutCT 03-13; BLACK RAIL RIDGE; DRAINAGE STUDY; 2004-08-02I ~I ·1 1 ·1 1 I I I I I I I I I I I I 'I ENGINEERING Professional Civil Engineer and Land Surveyor DRAINAGE STUDY TENTATIVE MAP CT 03-13 BLACK RAIL RIDGE SUBDIVISION 600 S. ANDREASEN DRIVE· SUITE E • ESCONDIDO, CA 92029 \. RECEIVED MAR 1 0. 2005 ENGINEERING DEPARTMENT PHONE: 760 741-3577 • FAX: 760 897-2165 • E-MAIL: MLBENESH@PACBELL.NET I I I I I ·1 1 I 1 I 1 I I I I I I 1 I Purpose CT 03-13 Drainage Study August 2, 2004 Pagel The purpose of this Drainage Study is to determine and compare the Pre-Development and Post-Development ultimate storm flows for the proposed project, and to determine the Water Quality Design Storm flows for the developed site. Ultimate Storm flows will be based on the 10 year and 100 year 6 hour storm as defined in the San Diego County Hydrology Manual. Water Quality Treatment Design Storm Flows will be based a storm event of 0.2 in/hr., which approximates an 85th percentile storm event. Site Description The proposed site consists of approximately 3.6 acres and adjoins Black Rail Road to the East, Poinsettia Lane to the North and Triton Street to the South. Currently the site is used for a plant nursery. There are no existing permanent structures. The proposed development is an 11 lot subdivision. There are no existing off-site storm flows entering the site. The storm runoff from the site, currently sheet flows across the westerly property line to the adjoining properties. Ultimately, all the runoff from this and adjacent sites ends up in a natural drainage area 600' westerly of this site. After development, a storm drain system will carry the runoff from this site to the natural channel. Hydrology The Rational Method as outlined in the San Diego Hydrology Manual is used to determine peak flows. Initial time of concentration, Ti is derived from Table 3-2 for the undeveloped site and for the developed site. Travel time is determined using either Figure 3-4 (for the undeveloped site), Figure 3-6 (for street flows) of the manning equation for trapezoidal cl1annels for flows in earth or concrete swales. Soil Type for the site is Type B per the latest San Diego County Soils Group Map. Table 1 -Anticipate4 vs. Existing 10 year Storm Flows Drainage Facility Existing Condition Proposed Proposed Flow from site, Ql0 Development Flow Development Flow, Q2 (CFS) from site, Ql0 (CFS) (CFS) Triton Street -3.3 2.0 Westerly Property Line -2.8 2.4 Total 4.4 6.1 4.4 DesiglJ of Vegetated Swa/e (Lots 1-5) Ideally, vegetated swales should be used on sites with slopes of less than 4 percent; runoff velocities within channels can become too high on steeper slopes, causing erosion and inhibiting in.filtration and filtering in the swale. Swale bottoms should not exceed 8 feet in width, with 4H:1V or flatter side slopes. The depth of the swale should carry the anticipated 10-year storm 600 S. ANDREASEN DRIVE' SUITE E • ESCONDIDO, CA 92029 PHONE: 760 741-3577 • FAX: 760 897-2165 • E-MAIL: MLBENESH@PACBELL.NET ! I I I I I I I I I I I I I I I I I I cr 03-13 Drainage Study August 2, 2004 Page 2 runoff with approximately 6 inches of freeboard. Typically, the swale should be designed to convey the runoff from a 2-year storm event, without erosion. Table 2 summarizes the results of the hydrology and hydraulic calculations for the proposed vegetated swale in Drainage Area 2c. Table 1 Hydrologic and Hydraulic Results for Proposed Vegetated Swale, Area 2c K § ~ ''= ~ t<S -.l:! ..:l CI a 0) .i:f. ~ l:j .... '" '" s (5 !:l ~ ~ en ..... d ~ '" ~ CI 4-< ...... U ~ 0) a '" t<S~ '0 0) ~ cJ .,S; ~ l:E ~ ~ ~ Ii .e-O) a J ~ '0 0) u ..9 W l±:: ~ 0) ~ .~ J ... W <:S ~~ ... ~ fr ~ ... ~ Q < ~ Q ~ Water Quality Storm, 1.97 0.46 9.7 0.2 0.18 0.4 0.6 (1=0.2 in/m) 2-Year Storm 1.97 0.46 9.7 2.23 2.0 1.5 1.8 10-Year Storm 1.97 0.46 9.7 3.09 2.8 1.9 2.1 The total depth of the swale varies but is at least l' below the pad grades. The bottom width of the swale is approximately 8 feet. with a 2:1 slope against Poinsettia Lane, and a slope of approximately 4:1 on the southerly side. A general rule of thumb fur sizing vegetated swales, as noted in the information included in Appendix A, is one percent of the area that drains into the swale. For the proposed swale on this project. the area required would be approximately 1180 square feet, or a swale 8 feet wide by 148 feet long, The actual dimensions of this swale will be 8 feet wide by 290 feet long Based on the maximum velocity expected for the design storm, and the length of the swale, ihe hydraulic residence time for runoff flowing through the swale is approximately 8 minutes. 600 S. ANDREASEN DRIVE· SUITE E • ESCONDIDO, CA 92029 PHONE: 760 741-3577 • FAX: 760 897-2165 • E-MAIL: MLBENESH@PACBELL.NET I I I I I I I I I I I I I I I II I I I Tc & Imp Area Calculations Node 100 -101 Area = 0.24 Ac Imp Area = 0.12 Ac % Imp = 0.12/0.24 = 50% Slope = 77.0-72.5/156 = 3% Ti = 6.0 min. Li = 90' Using: Tc = 6 min. A = 90/156 * 0.24 = 0.14 I = 6.56 in/hr C=0.60 Then Q = 0.6 cfs Assuming flow of Q/2 for each side of the lot: Channel Calculator Given Input Data: Shape ........................... Trapezoidal Solving for ..................... Depth of Flow Flowrate ........................ 0.3000 cfs Slope ........................... 0.0300 ft/ ft Manning's n ..................... 0.0200 Height .......................... 6.0000 in Bottom width .................... 0.0000 in Left slope ...................... 0.0200 ft/ft Right slope ..................... 0.0200 ft/ ft Computed Results: Depth ........................... 0.8039 in Velocity ........................ 1.3370 fps Flow area ....................... 0.2244 ft2 Flow perimeter .................. 8004031 in Hydraulic radius ................ 004019 in Top width ....................... 80.3871 in Area ............................ 12.5000 ft2 Perimeter ....................... 600.1200 in Percent full .................... 13.3978 % Then V= 1.3 fps Tt= (156-90)/(1.3*60) = 0.8 min. Tc = 6.0 + 0.8 = 6.8 min. Node 101 -102 Area = lAO Ac Imp Area = 0.70 Ac % Imp = 0.7/104 = 50% Slope = 72.5-36.7/565 = 6% cr 03-13 Drainage Study August 2, 2004 Page 3 600 S. ANDREASEN DRIVE· SUITE E • ESCONDIDO, CA 92029 PHONE: 760 741-3577 • FAX~ 760 897-2165 • E-MAIL~ MLBENESH@PACBELL.NET I I I I I I I I I I I I I I I I I I Assuming Avg Q = 1.4*3/2 + 0.9 =3 cfs V = 5.2 fps (Fig. 3.6) Tt = 565/ (5.2*60)=1.8 min. Node 200 -102 Area = 0.83 Ac Imp Area = 0.54 Ac % Imp = 0.53/0.83 = 64% use 65% Node 300 -301 Area = 0.58 Ac Imp Area = 0.20 Ac % Imp = 0.20/0.58 = 34% use 35% Slope = 67.0-64.0/200 = 1.5% use 2% Ti = 7.8 min. (fable 3-2, interpolated between 30% and 40% Imp.) Li = 80' Using: Tc = 7.8 min. A = 80/200 * 0.58 = 0.23 I = 5.54 in/hr C=0.52 Then Q = 0.7 cfs Assuming flow of Q/2 for each side of each lot Channel Calculator Given Input Data: Shape ........................... Trapezoidal Solving for ..................... Depth of Flow Flowrate ........................ 0.2000 cfs Slope ........................... 0.0150 ft./ft. Manning's n ..................... 0.0200 Height .......................... 6.0000 in Bottom width .................... 0.0000 in Left. slope ...................... 0.0200 ft./ft. Right slope ..................... 0.0200 ft./ ft. Computed Results: Depth ........................... 0.7863 in Velocity ........................ 0.9316 fps Flow area ....................... 0.2147 ft2 Flow perimeter .................. 78.6469 in Hydraulic radius ................ 0.3931 in Top width ....................... 78.6312 in Area ............................ 12.5000 ft2 Perimeter ....................... 600.1200 in Percent full .................... 13.1052 % Use V= 1 fps Tt= (200-80)/(1*60) = 2.0 min. Tc = 7.8 + 2.0 = 9.8 min. CT 03-13 Drainage Study August 2, 2004 Page 4 600 S. ANDREASEN DRIVE· SUITE E • ESCONDIDO, CA 92029 PHONE: 760 741-3577 • FAX: 760 897-2165 • E-MAIL: MLBENESH@PACBELL.NET I I I I I 1 I 1 ·1 1 I I I I I 1 I I I Node 301 -302 Area = 0.27 Ac Open Space/Landscape area, use 0% Imp. Ignore Length of Downdrain in determining Tt Assuming Avg Q = 0.27*1/2 + 1.3 =1.45 cfs (1 cfs/ ac -open space) Manning Pipe Calculator Given Input Data: Shape ........................... Elliptical Solving for ..................... Depth of Flow Minor axis ...................... 24.0000 in Major axis ...................... 36.0000 in Flowrate ........................ 1.4500 cfs Slope ........................... 0.0200 ftl ft Manning's n ..................... 0.0150 Computed Results: Depth ........................... 3.0212 in Area ............................ 4.7124 ft2 Wetted Area ..................... 0.3435 ft2 Wetted Perimeter ................ 24.9215 in Perimeter ....................... 95.1927 in Velocity ........................ 4.2214 fps Hydraulic Radius ................ 1.9847 in Percent Full .................... 12.5882 % Full flow Flowrate .............. 46.6548 cfs Full flow velocity .............. 9.9005 fps Use V= 4.2 fps Node 302 -303 Area = 1.12 Ac Imp Area = 0.15 Ac % Imp = 13% use 20% Ignore Length of Downdrain in determining Tt. AssumingAvg Q = 1.12*2/2 + 1.6 =2.7 cfs (2 cfs/ac) Channel Calculator Given Input Data: Shape ........................... Trapezoidal Solving for ..................... Depth of Flow Flowrate ........................ 2.7000 cfs Slope ........................... 0.0200 ft/ft Manning's n ..................... 0.0200 Height .......................... 6.0000 in Bottom width .................... 96.0000 in Left slope ...................... 0.5000 ft/ ft Right slope ..................... 0.2500 ft/ ft Computed Results: Depth ........................... 1.5128 in Velocity ........................ 2.5564 fps 600 S. ANDREASEN DRIVE' SUITE E • ESCONDIDO, CA 92029 CT 03-13 Drainage Study August 2, 2004 PageS PHONE: 760 741-3577 • FAX: 760 897-2165 • E-MAIL: MLBENESH@PACBELL.NET I I I I I I I I I I I I I I I I I I I Flow area ....................... 1.0562 ft2 Flow perimeter .................. 105.6200 in Hydraulic radius ................ 1.4400 in Top width ....................... 105.0766 in Area ............................ 4.7500 ft2 Perimeter ....................... 134.1550 in Percent full .................... 25.2128 % Use V= 2.6 fps Storm Drain Hydraulic Grade line Calculations cr 03-13 Drainage Study August 2, 2004 Page 6 Hydraulic grade line calculations are based on the Mannings equation. Outlet losses are based on the velocity head. In cases of subcritical flow, the grade line is calculated in an upstream. direction fur the reach adding friction loss to the downstream grade line elevation. In the case of supercritical flow, the grade line is based on an assumption of critical depth at the manhole or Catch Basin outlet and flow in the downstream pipe is assumed to be normal depth for the reach. Catch Basil1 Capacity -T nton S !reet In the interim condition, with the berm installed at the West end of Triton Street to direct the street flow across the street from the South, the catch basin will operate in a sump condition. Ultimately, when Triton is widened to its full 40' width and a catch basin is installed to pick up the South side flows, the catch basin will operate in an intercept condition. Interim Condition: Q100=7.8 cfs L=14' S= 0.01 Local Depression = 0.33' Therefore: Depth @ Inlet = CQI (L *3.0» 2/3 = 0.33' Ultimate Condition Q100=4.9 cfs L=14' S= 0.01 Local Depression = 0.33' Depth of Flow in Gutter = 0.38' (Using Figure 3-6) Capacity = 0.7(0.33+0.38) 3/2 (14)=5.9 cfs > 4.9 cfs Capacity of Type FAC Dike Q100 = 7.8-4.9 = 2.9 cfs S = 0.04 Therefore: Channel Calculator Given Input Data: Shape ........................... Trapezoidal 600 S. ANDREASEN DRIVE· SUITE E • ESCONDIDO, CA 92029 PHONE: 760 741-3577 • FAX: 760 897-2165 • E-MAIL: MLBENESH@PACBELL.NET I I I I I I I I I I I I I I I I I I Solving for ..................... Depth of Flow Flowrate ........................ 2.9000 cfs Slope ........................... 0.0400 ft/ ft Manning's n ..................... 0.0175 Height .......................... 6.0000 in Bottom width .................... 0.0000 in Left slope ...................... 0.3000 ft/ ft Right slope ..................... 0.0200 ft/ ft Computed Results: Depth ........................... 2.1486 in Velocity ........................ 3.3921 fps Flow area ....................... 0.8549 ft2 Flow perimeter .................. 114.9312 in Hydraulic radius ................ 1.0712 in Top width ....................... 114.5943 in Area ............................ 6.6667 ft2 Perimeter ....................... 320.9406 in Percent full .................... 35.8107 % Depth of Flow = (2.15/12) = 0.18' < 0.5' OK HGL @ existing Manhole -Sta 0+00 From Dwg. No. 360-3B, Ql00 existing at outlet of SD = 12.7 cfs. Adding Q from site and ignoringTc variations, Qtotal = 12.7 + 10.2 = 22.9 cfs Section Downstream of Pipe = 2.5' Wide Rectangular channel, s=0.02 Therefore: Channel Calculator Given Input Data: Shape ........................... Rectangular Solving for ..................... Depth of Flow Flowrate ........................ 22.9000 cfs Slope ........................... 0.0200 ft/ft Manning's n ..................... 0.0150 Height .......................... 30.0000 in Bottom width .................... 30.0000 in Computed Results: Depth ........................... 11.7142 in Velocity ........................ 9.3835 fps Flow area ....................... 2.4405 ft2 Flow perimeter .................. 53.4284 in Hydraulic radius ................ 6.5775 in Top width ....................... 30.0000 in Area ............................ 6.2500 ft2 Perimeter ....................... 90.0000 in Percent full.................... 39.0474 % Depth Down Stream of Outlet = (11.7/12) = 1.0' Assume Hgl @ outlet = soffit of pipe = 309.50 Therefore: cr 03-13 Drainage Study August 2,.2004 Page 7 600 S. ANDREASEN DRIVE' SUITE E • ESCONDIDO, CA 92029 PHONE: 760 741-3577 • FAX: 760 897-2165 • E-MAIL: MLBENESH@PACBELL.NET I I I I I I I I I I I I I I I I I I I Manning Pipe Calculator Given Input Data: Shape ........................... Circular Solving for ..................... Friction Slope Diameter ........................ 18.0000 in Depth ........................... 18.0000 in Flowrate ........................ 22.9000 cfs Manning's n ..................... 0.0150 Computed Results: Slope ........................... 0.0633 ft/ft Area ............................ 1.7671 ft2 Wetted Area ..................... 1.7671 ft2 Wetted Perimeter ................ 56.5487 in Perimeter ....................... 56.5487 in Velocity ........................ 12.9587 fps Hydraulic Radius ................ 4.5000 in Percent Full .................... 100.0000 % Full flow Flowrate .............. 22.9000 cfs Full flow velocity .............. 12.9587 fps Sf, flowing full = 0.063 V= 13.0 fps HGL @ S'ly Inlet = 309.50 + (0.063)(51.79) = 312.76' Inlet Loss = 1.2 V2/2g = 3.15' HGL upstream = 312.76 + 3.15 = 315.91' Q upstream = 7.3 + 10.2 = 17.5 cfs Therefore: Manning Pipe Calculator Given Input Data: Shape ........................... Circular Solving for ..................... Friction Slope Diameter ........................ 18.0000 in Depth ........................... 18.0000 in Flowrate ........................ 17.5000 cfs Manning's n ..................... 0.0150 Computed Results: Slope ........................... 0.0370 ft/ft Area ............................ 1.7671 ft2 Wetted Area ..................... 1.7671 ft2 Wetted Perimeter ................ 56.5487 in Perimeter ....................... 56.5487 in Velocity ........................ 9.9030 fps Hydraulic Radius ................ 4.5000 in Percent Full .................... 100.0000 % Full flow Flowrate .............. 17.5000 cfs Full flow velocity .............. 9.9030 fps Sf, flowing full = 0.0370 V upstream = 9.90 fps HGL @ Proposed Manhole = 315.91 +28.38(0.037) = 316.96' cr 03-13 Drainage Study August 2, 2004 Page 8 600 S. ANDREASEN DRIVE· SUITE E • ESCONDIDO, CA 92029 PHONE: 760 741-3577 • FAX: 760 897-2165 • E-MAIL: MLBENESH@PACBELL.NET I I I I I I I I I I I I I I I 'I I I I HGL @ Manhole -Sta 2+42.64 Q downstream = Q upstream = 10.2 cfs Invert Downstream of manhole = 328.50' 18" RCP s=0.0802 Therefore: Manning Pipe Calculator Given Input Data: Shape ........................... Circular Solving for ..................... Depth of Flow Diameter ........................ 18.0000 in Flowrate ........................ 10.2000 cfs Slope ........................... 0.0802 ft./ ft. Manning's n ..................... 0.0150 Computed Results: Depth ........................... 7.8685 in Area ............................ 1.7671 ft2 Wetted Area ..................... 0.7425 ft2 Wetted Perimeter ................ 26.0054 in Perimeter ....................... 56.5487 in Velocity ........................ 13.7371 fps Hydraulic Radius ................ 4.1115 in Percent Full .................... 43.7141 % Full flow Flowrate .............. 25.7815 cfs Full flow velocity .............. 14.5893 fps Critical Information Critical depth .................. 15.4735 in Critical slope .................. 0.0095 ft./ft. Critical velocity ............... 6.0257 fps Critical area ................... 1.6928 ft2 Critical perimeter .............. 41.2213 in Critical hydraulic radius ....... 5.9134 in Critical top width .............. 18.0000 in Specific energy ................. 3.5883 ft. Minimum energy .................. 1.9342 ft. Froude number ................... 3.4285 Flow condition .................. Supercritical Supercritical flow condition, assume Dc at outlet. Dn = 7.9/12 = 0.66' Vn = 13.7 fps Dc=15.5/12 = 1.29' Vc=6.0 fps Outlet Loss = 1.2V2/2g = 0.67' HGL @ Manhole = 328.50 + 0.67 + 1.29 = 330.46' CT 03-13 Drainage Study August 2, 2004 Page 9 600 S. ANDREASEN DRIVE· SUITE E • ESCONDIDO, CA 92029 PHONE: 760 741-3577 • FAX: 760 897-2165 • E-MAIL: MLBENESH@PACBELL.NET I I I I I I I I I I I I I I I I I I I HGL @ CB -Sta 4+30.80 Q downstream = 10.2 cfs Q upstream = 7.8 cfs Invert Downstream of CB = 332.45' 18" RCP s=0.02 Therefore: Manning Pipe Calculator Given Input Data: Shape ........................... Circular Solving for ..................... Depth of Flow Diameter ........................ 18.0000 in Flowrate ........................ 10.2000 cfs Slope ........................... 0.0200 ft/ft Manning's n ..................... 0.0150 Computed Results: Depth ........................... 12.0925 in Area ............................ 1.7671 ft2 Wetted Area ..................... 1.2624 ft2 Wetted Perimeter ................ 34.5880 in Perimeter ....................... 56.5487 in Velocity ........................ 8.0799 fps Hydraulic Radius ................ 5.2557 in Percent Full .................... 67.1805 % Full flow Flowrate .............. 12.8747 cfs Full flow velocity .............. 7.2856 fps Critical Information Critical depth .................. 15.4735 in Critical slope .................. 0.0095 ft/ ft Critical velocity ............... 6.0257 fps Critical area ................... 1.6928 ft2 Critical perimeter .............. 41.2213 in Critical hydraulic radius ....... 5.9134 in Critical top width .............. 18.0000 in Specific energy ................. 2.0217 ft Minimum energy .................. 1.9342 ft Froude number ................... 1.5617 Flow condition .................. Supercritical Supercritical flow condition, assume Dc at outlet. Dn = 12.09/12 = 1.01' Vn = 8.1 fps Dc=15.5/12=1.29' Vc=6.03 fps Outlet Loss = 1.2v2/2g = 0.68' HGL @ CB = 332.45 + 0.68 + 1.29 = 334.42' cr 03-13 Drainage Study August 2, 2004 Page 10 600 S. ANDREASEN DRIVE' SUITE E • ESCONDIDO, CA 92029 PHONE: 760 741-3577 • FAX: 760 897-2165 • E-MAIL: MLBENESH@PACBELL.NET I I I I I I I I I I I I I I I I I I. I HGL @ CB -Sta 4+30.80 Q downstream = 7.8 cfs Invert Downstream of CB = 333.15' 18" RCP s=0.005 Depth of Water @ 4+32.30 = 334.42-332.57 = 1.85' Therefore: Manning Pipe Calculator Given Input Data: Shape ........................... Circular Solving for ..................... Friction Slope Diameter ........................ 18.0000 in Depth ........................... 18.0000 in Flowrate ........................ 7.8000 cfs Manning's n ..................... 0.0150 Computed Results: Slope ........................... 0.0073 ftl ft Area ............................ 1.7671 ft2 Wetted Area ..................... 1.7671 ft2 Wetted Perimeter ................ 56.5487 in Perimeter ....................... 56.5487 in Velocity ........................ 4.4139 fps Hydraulic Radius ................ 4.5000 in Percent Full .................... 100.0000 % Full flow Flowrate .............. 7.8000 cfs Full flow velocity .............. 4.4139 fps Critical Information Critical depth .................. 13.2558 in Critical slope .................. 0.0087 ft/ft Critical velocity ............... 5.5102 fps Critical area ................... 1.4155 ft2 Critical perimeter .............. 36.7860 in Critical hydraulic radius ....... 5.5412 in Critical top wid.th .............. 18.0000 in Specific energy ................. 1.7344 ft Minimum energy .................. 1.6570 ft Froude number ................... 0.5916 Flow condition .................. Subcritical Subcritical flow condition. Sf flowing full = 0.0073 V=4.41 fps HGL Downstream of CB = 334.42 + (0.0073)(116.41) = 335.27' Outlet Loss = = 1.2v2/2g = 0.36' HGL @ CB = 335.27 + 0.36 = 335.63' TC @ Inlet = 337.10 CF = 6" + 4" = 10" =0.83' Freeboard 337.10 0.83 335.63 CT 03-13 Drainage Study August 2, 2004 Page 11 = 0.64' 600 S. ANDREASEN DRIVE' SUITE E • ESCONDIDO, CA 92029 PHONE: 760 741-3577 • FAX: 760 897-2165 • E-MAIL: MLBENESH@PACBELL.NET I I I I I I I I I I I I I I I I I I I San Diego County Soils Group Map I 1 T-+- ~----,--, ! Group A GroupB Group C GroupD Undetermined Unknown 600 s. ANDREASEN DRIVE' SUITE E • ESCONDIDO, CA 92029 PHONE: 760 741-3577 • FAX: 760 897-2165 • E-MAIL: MLBENESH@PACBELL.NET ------------------- Rational Method Calculation Form Project: CT 03-13 Drainage Soil & A C CA :teA I Frequency 100 Year Post-Development Q Slope Section Area Development Aeres In.lHr. CFS 100-101 B -50'0 Imp 0.24 0.58 0.14 0.14 6.05 0.8 1/2 St 101-102 B -50'0 Imp 1.40 0.81 0.06 0.58 0.95 5.20 4.9 200-102 B -65'0 Imp 0.83 0.67 0.56 1.51 5.20 7.8 0.005 21" RCP 300-301 B -35% Imp 0.58 0.48 0.28 0.28 4.78 1.3 0.02 D-75 B -0'0 Imp 301-302 0.27 0.25 0.07 0.35 4.60 1.6 0.02 Swale B -20% Imp 0.38 302·303 1.12 0.43 0.77 4.14 3.2 Conf 303 Qil See SD County Hydrology Manual 10.2 QT2 See SD County Hydrology Manual 9.4 303 Qil 4.44 2.28 10.2 .. . .. . . :~ ;';:~}'?;'\l:~ :", . V L T '/See. Ft. Min. 5.2 565 1.8 4.5 120 0.4 4.2 150 0.6 2.6 290 1.9 SumT 6.8 8.6 8.6 9.1 9.8 10.4 12.3 10.9 Calculated by MB Oate:2 August 2004 Remarks See Te Cales. Fig. 3.6, See Cales S 'Iy Side Triton Conf@ 303 See Te Cales. 2% V-Gutter 2% Swale -Conf 303 Tc=[(I(CA)7.44P6)/Q]1.55 I 1 . ------------------- . i Rational Method Calculation Form Project: CT 03·13 Drainage Soil & A Area Development Acres 100-101 B -50'0 Imp 0.24 101-102 B -50'0 Imp 1.40 200-102 B -65'0 Imp 0.83 C CA l:CA I In.lHr. 0.58 0.14 0.14 3.89 0.58 0.81 0.95 3.34 0.67 0.56 1.51 3.34 I 300-301 B -35'0 Imp 0.58 0.48 0.28 0.28 3.07 301-302 B -0'0 Imp 0.27 0.25 0.07 0.35 2.96 302-303 B -20'0 Imp 1.12 0.38 0.43 0.77 2.'06 Conf 303 Qn See SD County Hydrology Manual QT2 See SD County Hydrology Manual 303 Qn 4.44 2.28 ,," . '" ,'.' . ;':.:~: .. :. ':'" Frequency 10 Year Post-Development Q Slope Section CFS 0.5 0.06 112 St 3.2 5.0 0.005 21" RCP 0.9 0.02 D-75 1.0 2.1 0.02 Swale 6.6 6.1 6.6 "- V I/See. 5.2 4.5 4.2 2.6 L T SumT Ft. Min. 565 1.8 6.8 8.6 120 0.4 8.6 9.1 9.8 150 0.6 10.4 290 1.9 12.3 10.9 ------- Calculated by MB Oate:2 August 2004 Remarks See Tc Cales. Fig. 3.6, See Cales S'ly Side Triton Conf@ 303 See Tc Cales. 2% V-Gutter 2% Swale -Conf 303 Te=[(!(CA)7.44P6)/Q]1.55 I . --------------~---- ! i Rational Method Calculation Form Project: CT 03·13 Drainage Soil & A Area Development Acres 100-101 B -50'Yo Imp 0.24 101-102 B -5010 Imp 1.40 200-102 B -6510 Imp 0.83 300-301 B -35% Imp 0.58 301-302 B -010 Imp 0.27 302-303 B -2010 Imp 1.12 C CA :tCA I In.lHr. 0.58 0.14 0.14 2.81 0.58 0.81 0.95 2.41 0.67 0.56 1.51 2.41 0.48 0.28 0.28 2.22 0.25 0.07 0.35 2.14 0.38 0.43 0.77 1.9'2 Conf 303 Qn See SD County Hydrology Manual QT2 See SD County Hydrology Manual 303 _~~ '-----_gn ._~ ~ ~J __ . 2.28 .-----_ . . ... , ..... Frequency 2 Year Post-Development Q Slope Section CFS 0.4 0.06 1/2 St 2.3 3.6 0.005 21" RCP 0.6 0.02 D-75 0.7 0.02 Swale 1.5 4.7 4.4 .1·!._ V L '/See. Ft. 5.2 565 4.5 120 4.2 150 2.6 290 T SumT Min. 1.8 6.8 8.6 0.4 8.6 9.1 9.8 0.6 10.4 1.9 12.3 ,-l~~ Calculated by MB Date:2 August 2004 Remarks See Te Cales. Fig. 3.6, See Cales S'ly Side Triton Conf@ 303 See T c Cales. 210 V-Guttel" 210 Swale -Conf 303 .,!e=[(I(CA)7.44P6)1Q]1.55 , ------------------- Rational Method Calculation Form Project: CT 03-13 Drainage Soil & A Area Development Acres Area A B -10'10 Imp 3.58 . :.' ;~: ..... C CA ::£CA 0.32 1.15 1.15 I Frequency 100 Year Pre-Development Q Slope Section In.lHr. CFS 4.54 5.2 .. V '/Sec. L T SumT Ft. Min. 10.6 Calculated by MB Date:2 August 2004 Remarks L= 675' Slope = 7'10 Table 3-2 (Interpolated) Lm=100', Ti=7.4 Min Tt= 3.2 Min (Fig 3-4) Tc=7.4+3.2=10.6 ------------------- i I Rational Method Calculation Form Project: CT 03·13 Drainage Soil & A Area Development Aeres Area A B -lO,},o Imp 3.58 ".}:'.',\\;';"'" C CA ECA I In.IHr. 0.32 1.15 1.15 2.92 .. Frequency 10 Year Pre-Development Q Slope Section CFS 3.3 V L '/See. Ft. T SumT Min. 10.6 Calculated by MB Date:2 August 2004 Remarks L= 675' Slope = 7% Table 3-2 (Interpolated) Lm=100', Ti=7.4 Min Tt= 3.2 Min (Fig 3-4) Tc=7.4+3.2=10.6 ------------------- ;--.J \-;:' ( ( COUNTY OF SAN DIEGO DEPARTMENT OF SANITATION , FLOOD CONTROL lO-YEAR 6-HOUR PRECIPITATlor~ .' , 30' "I.b , !Ii f ~ '-< lS' 1'11\ LJ "' < • 33' J 4;' .L"' __ +-_I_~ ._ .. __ .... -.... _-_. --,. ........ ~ . PrtPI 'ltd by U.S, OEPARTME T OF COMMERCE ffAT'ONAI. OCtANt!: AND M' :c)ltttitRIC'''D~tlHJI'rR ... TtOtf SPECIA!,. 'STUDIES DRANCH, OFFICE 01" I 'OROLOGY, NAT,ONAL WEATHER IBft\llCI 30' J IDI1I4 ... £'t-"-~-"r· 1181' 4,' 30' IS' 1170 45' 30' ( lS' 116- ----------.--------- .... "j4 ~\> o 1 . J COuillTY OF SAN PIEGO. • DEPARTMENT OF SANITATtON s- FLOOD CONTROL lO-YEAR 24-lfOU'R PRECIPITATIOfJ "'20 .... dSOPlUVIALS bF 10 .. YEAR 24 .. HOUR . 45 t !fd"~~-(' ~ I"" < • '" 30' . 'I' l.,~ I ,,<:: ',._ lS' ""f.I---:--........ ----l ,,0 • 91! 451.!.1---+~-1--: . IlBO 4,' 30' lS' Jl7° 1'5' 30· -, 15·' Jl6° - - - - - --.-- - - - - - - - - - -, COUNTY OF SAN DIEGO . DEPARTMENT OF SANITArION & FLOOD CONTROL "' 2-YEAR 6-HOUR PRECIPITATIO~l ,-10-ISOPLUVIALS OF 2· 'fEAR G·.~OUR 45 1 DCi)!'Ce't(",..V ,,~ ,. ),'iiS' 30' I "t IS' I I \: l--it 33·' 4 , 10f t I :::.J."~' t4 J. "" t::::~j' f Sf ,. v .. AN undO ~..."ryl.") I 7 " P,.plI ... dby U.S. DEPARTMENT OF COMMERCE NATIONAL OCtANIC MID ATMOSPHtltlC APMINtlTIMTIOlf 'a:CIAL STUDIU BRANCH. OFFICt OF lI\'I'IROt.O(W. NATIONAL WEATHER SIRVICE \) ~ 30 1 1180 'f; I 30' I 45' 30' 15' 117' ., IS' liS' ------------------- .. ,. I ) ' . .. " ) COUNTY OF SAN DIEGO . DEPARTMENT OF SANITATION & FLOOD CONTROL • \ ... ' 45' . 30' l,t .. ,,', 45' I Prep.'rlel 11)' , u.s. DEPARTMENT OF COMMERCE N .... TIONAI.. OCEA:-;IC AND ATf,lOIlJ'HUIC ADMINISTRATION SPECIAL STUDI!5 BRANCH. O·,."IC& OF IIVDROLOO' .. NATION"!" YilATHEJit 'SIlVlel .... 'i' :r CO \,.J "'J ;0' " +-I I 118· '.S' 30' J :OoJU .... u ioU .... I '.. i ' t .. IS' 117· 45' 30' 151 116· ------------ 10.0 9.0 8.0 7.0 6.0 ~ l'-.f'ro..!' '" I I! II III II I II ~l'-.!' N I! !! ! II N.. "" ........ ~I .... !'.~ ! III 1 II Ij II II'l. ""~ ro...~ .... i ~...." . 1 EQUATION I ..... .... ,.... I I =. 7.44 Pa 0-0.645 )' ~ """ . I = Intensity (in/hr) " ...." I I r---"" '" ri-. '" I Pa = 6-Hour Precipitation (in) 5.0 4.0 )~ r-...", Ii" i 0 = Duration (min) 3. 2. 'C' 5 ~ -5 .5 1. . I..,.... "" "" I '" I I I . 1 1",-I : 1 . ii' " ' ~, , : .... ~ . ~ ) ! I"'..... ,....... ,,! " l~" : I ," i' .... " I I "'~ ". i"'~ I ..... r-. I i 1'1'''' ; i I"~ro-"" ~ " I l"'1'" " iO. ·@o. J I "" I' 3~~~4-~++~4++H~+H~ffi*~+H~~~~*ffi~~~&+~~~~~ ~ Il'WIl roo. ~O o o o o o. 0. 7 .... ~ I ! .... 1" '" ) , ~ _, 1 I: I" I~ I' ) I i I" I. I l i, ~ ~ I I r-.I'r-. 3 .," .. , , ~....,. ! , . I---.-'.-.. -'" "'"' ....' .. 1 '~i+;'ffff~ I ! I -:! I I I !, I; 5 6 7·8 910 15 20 30 40 50 Minutes Duration 2 3 4 Hours 5 6 'T' J: o c .. "tJ iil Q. 6.0 'E. 5.5 ~ s.O g 4.53- . 0 4.0 m 3.5~ 3.0 2.5 2.0 1.5 1.0 Intenslty·Duratlon Design Chart -Template - ----- Directions for Application: (1) From precipitation maps determine 6 hr and 24 hr amounts for the selected frequency. These maps are included in the County Hydrology Manual (10, 50. and 100 yr maps included in the Design and Procedure Manual). (2) Adjust 6 hr precipitation (if necessary) so that it is within the range of 45% to 65% of the 24 hr precipitation (not applicaple to Desert). (3) Plot 6 hr precipitation on the right side of the chart. (4) Draw a line through the point parallel to the plotted lines . (5) This line is the intensity-duration curve for the location being analyzed. Application Form: (a) Selected frequency ...L year (b)P6= 1..:;Lln"P24= '1..0 ':26 = rur; %(2) i ?_ 4 (e) Adjusted PS{2):; ...1..:..2-In. (d) tx = __ min. (e) I :; __ In./hr • Note: This chart replaces the Intensity-Duration-Frequency curves used since 1965. pi; .: 1 ·:1.s[·r:),S:: .. 3",:3,?: ... L:",~,5: 5 .. ,.,~.5.~ 'G" Durallon' I I' I I. I I: I I I: I : I .... --'~ 2,6?. _9:~~; 5,?? _ ~.5~: 7.90. ~.2~l10.54; !l.8S· 13.,17~ 11.,,\9;1~,.~1. ."" .... ,} ?,'.? ... ~.l~; 4 .. ?4.: ~ . .sq.: 6.3~:7.42l ~.4a ",9.54 . 10.60111.66! 12,~2 ~O 1·~ .;?A~~.~!?!.._1,?L~!9?§:~OUH~",J.@. .... !3,,~? .. : 9.~7 J9:.1.!. ..... ".t~ ,,1:!l.Q,,:~'~.~f.?..:~~P!g,1.:,~!8,,~:~.,5~.; 5,!~", 8M .. : 6.4~., .7·t~.; ?:7~:. 20 1,08 '.62! 2.15;2.69. 3.23·3.77, 4.31 4.85 i 5,39' 5.93: 6.46 . r ............... -._-~·_· ___ ·~ __ ...... _ .. __ ~·t'_' ___ '",·M_" , .. .. ~ 0.93 .. 1-.40, 1.~~ !?:~3.;2.80!3.27~ 3.73, 4.20 . 4.67 ; 5.13 i 5,~ 30 0,83; 1.24! 1..66~ 2.07. 2!49. 2.~~ .3,~., .~~3 .. ~.15 t .4:?~.1 ~.9~ ~ .0:1l9 : 1.p3! 1..3~. 1.72.2.07.2.41: 2.76 . 3.10 ~ 3.45 [ 3.19 i 4.13 ?:O Q.60 .. 0:~Oj 1,1~.I.,4!l_.P9.~.09;.g.~9 ... 2..~\l.; ?~9~ L~·2~.i.~·5t! . " .. "".@ .~,.53 :0.80: 1.06.1.33.1.59.1.86;2.12.2.39: 2.65,2.92; 3.18 .. ".!l«! _0:41. ;().G~fP:~ J.9.2. ... 1:~3, 1.43. l,6?; 1.~4l2,04: .~~~~.i ?.~~ 1~ .0.34 . 0.51l 0.68.0.85: 1.02; 1.19, 1.36: 1,53. 1.70, 1.61: 2.04 .. .1.@ .Q,g~. ~OA4LQ,~~.!.Q:,?,~,".9:~.L1:.Q~, 1. ... 1~. 1.32 I 1.47 , 1:6~:J.!?'~. .'"" .. 1.~ .0 .. 2,6 ,!?:391.9.:?~.Lq·~5 .. Q.7~l9.-\l! .. ):~ .:..1. !~,I. t.'.~~",~""1:.¥ L 1 ·!F . . "'.~~ o:?? .. O.33f.Q,~~.: 9.~.4 .. ~·~lW~.6i !l.87 : 0.98 : 1·<?!\._. 1.·19: .t~. ~ .O:'.~ .O.2S.~,?!U!:4.L():~:.0.~~jP~ .. ; q .. ~ :""o,~ .. lA~.3. ':.1~. 360 0.17 0.2510.33: 0.42: 0.50'0.58 0.67! 0.75 i 0,84 0.92! 1.00 FIGURE ~ - --- N i"o. .,... " r-..:..l i ..... 10.0 9.0 S.O 7.0 6.0 r-J 1-0." 3. ) . ..... r .... ..... ) I ~. ..... I . ; 1 5.0 4.0 ~ 1'", ) I 2.0 'C' ~ ~ c: 1. ~o. ·i1!o. Q) £l0' o. o. o. o. o o : ! ) ~ , T 3 . , r , I 3 , 5 4 ! 3 2 . - i "I I ' , - ~ " 1'0 l"-I' r-. l"-I' ,.... " ~,.... I'r-. r...r-.., ... I~ r.... r--r--100., r--r.... I"-i"o. I ~ r-. '" 'r-. ' '" j i'i"o. 1"-", """ I " 1--,. +- 5 6 7 8 910 -- I J 1 r-. I I ..... , i' ro\, i' r.;.. I' ! ~ I " I .... I i I ! I I , I I , , - I t5 20 30 MinUfEiS ----- , .. t 1 11 I ! III : I I I i II 1 I EQUATION , I = '7.44 Ps 0"0.S45 , i I = Intensity (in/hr) ! i Ps = 6·Hour Precipitation (in) r I o = Duration (min) I I 1 r : I ~~ I I' I"-I"-~ to, ~"" I I' r-,.i'o ! ... ... r--~ i ~ .... I"-r-. ~ I l"-t-. '" i ... "" , I' ~ 100.,1' "" I i I .. "" i'io I I· ! 1' .... ...... - ; I , , .~ ....... _R" •• 1 I I I l 40 50· 2 3 4 5 6 Duration Hours ' - i ~ {l . 6.0 "9. 5.5 g 5.0 g 4.55' 4.0 i 3.5 ~ 3.0 2.5 2.0 1.5 1.0 Intenllty-Duratlon Design Chart,. Template ------ Directions for Application: (1) From precipitation maps determine 6 hr and 24 hr amounts for the selected frequency. These maps are induded in the County Hydrology Manual (10,50, and 100 yrmaps included in the Design and Procedure Manual). (2) Adjust 6 hr precipitation (if necessary) so that it is within the range of 45% to 65% of the 24 hr precipitation (not applicaple to Desert). (3) Plot 6 hr precipitation on the right side of the chart. (4) Draw a line through the point parallel to the plotted lines. (5) This line Is the intensity-duration curve for the location being analyzed. Application Form: (a) Selected frequency 1m.. year (b) P6 = 2.€> in., P24 = LJ.t5 ,~= ~ %(2) 24 (C) Adjusted P6(2) = ~ in. (d) tx = __ min. (e) I = __ . _ in.lhr. Note: This chart replaces the Intensity-Duration-Frequency curves used since 1965. ....... -.... f ...... "...... • .• • •• • ........ . P6 1. 1.~ t .~ .• ~,~ .... 3 ...... ~,!L .... L ... 4,.!t.. 5.:.5.5 i .6 Duration I I; I I I I: I I I' I ! I ...... "'5 2.63· 3.951 5.27: 6.59 7.90 9.22' 10.54 11.66' 13.17:14.49: 15.81 .. ....... : .. ~ :?;i.2.:;~:1·~14.~4r5;.:i~::6.:3( 7.4:2.:·~.48 : 9.54 :10.60i 1 1,.001 12.72 10 ~.f?8.: ?5~~.~:.;l? .. ;._f:?'J .:_!?.'~_L~:!Xl.; _~,?1 ..... 7.·[l!:L. ~,4g_; .. ~·;n iJ.Q.J..1. ....... .15 J!~Q_ J,Jl§.t.?·5S!.L~"g~_.,~·~ . .1:!?~.: 5,1!, .. ~B1 .. , ~.49. L?.'! 3. i.!.'?~. 20 LOa 1.62·2.15:2.69;3.233.77: 4.31 4.85: 5.39: 6.93! 6.46 .. ~ . 9.93 ; ~·~l1.:~7 r~:~( 2:~O :·3:2i;-:i:r3~·4.2ci:-~':61 ;"5'.13; 5:69. 0.83 ; ~.M, 1.~6i 2.07. 2.49.2.~O: ~:~ ,._~!:3".4 .. 1.5 ,.4,.~.l -;I.9~ ..... "\9. ,.0.69 .' 1.0311 .. ~8: 1.72,2.1)7.2.41 i 2.76 . 3.10 . 3.45 l 3.79! 4.13 ~ 0.60. ;0.901.1.11'1, 1,~9 .. ~:r9 .':!·9.~ .. ?·~9 .• 2,Y.!:l._ ?!~~.l3!g~.l ~.!!~ .. .. " ...... !!o. . 0.53 ;0.80: 1.06; 1.33.1.59.1.86; 2.12 . 2.39 . 2.65 i 2.92; 3.18 ... " .~ p:~1.; 0.61 LC!:~2; 1._Q? .•. 1.,2~;.!.,4~; .1.~3.j 1.~ •. ~~ : .~:.2~: ~.~!i. . l;ZO 0.34 :0.!i1iO.68lo.65~·1.02. 1..19; 1.36 \ 1,53.: 1.70.1.87: 2.04 .... l~ _Q.!!'~"(Q:4.~f9:~9.L().!.~:.q,~:.~ .. O.3; 1.:.1~ : 1.3~. 1.47 J62_d:?~ .. ........ J~ . Q..~~. ~ 0..39 r (),5~'1 Q.~5.; 0.7~; ():~.1.t tc!.~. ~ .1.,1~L._l.,;!! .: .1:~ \ ~ .f>7 ..... ~_"\9. . Q._?.?.. ;0..33. Q,.43 .. o..51 . ..I:H5.;();?!3. 9 .. 87 . 0.98. l·.GS_: U.~.lJ:.~. ~ . 9,'~!:l . O.28~ (),~B! Q:47 .. 9:~: () .. ~~.Q}~.,. q·~!L Q:9.L.!:.~. ~. ~ :.1;3. 360 0.17 0.25!0.33'O.42 0.50:0.58.0.6710.75 0.84 0.92' 1.00 FIGURE ~ - --- 10.0 9.0 8.0 7.0 " )" 6,0 r... ~ " " " "I .... " I , .... 1' I I " 5,0 ~N'l " 4,0 3,0 i l" 2,0 , I C ::0 ~ .r::. g1. ~o. ·~o. ~o. ..., o. o. I ) ! I , 3 i 1 I ) : I 5 i " .... I 1 j - - " I' '" I' I' " .... ~ I' i'o.. ~ ... I ~ ... .... r.... ~ ... r--. " ~i' I' f'. I-i' 1'1' I .... I' . ~i'. "" ~ I' I I I 11 ! I I I o o o ! i I-1-' .. ·1-1-1-_. ..• .-- i o I . 5 6 1 8 9 10 15 - I ~ ! I " ! ! " I' " ~ " " ~ ! I N , r.... i ! i ! 1 : ; , , ! , .I !I . . .. ; I I 20 30 Miiltlfes -- til II! III I ! I I I i I I : I I I j , T I 40 50 Duration --- I ! I EQUATlON I ,. 7.44 P6 0-O.645 I ,. Intensity {in/hr} P6 = 6·Hour Precipitation (in) D :: Duration (min) 1'1' " " ~ ~ I " ... I'" I' I. I' i'~ I_ ~ I'" 1'1' ~ " r-. l"" '" .... . 'I' I" I' "I' ""I' - ----. ~ ~ ~.. . .. - - I i III ! i In ! ~ ! , 0) ± ~ 4' 6.01 5.5 ~ 5.0 ;:I 4.53- 4.0 g. 3,51& 3.0 2.5 2.0 1,5 1.0 2 3 4 56 Hours Intensity"Duration Design Chart· Template ------ Directions for Application: (1) From precipitation maps determine 6 hr and 24 hr amounts for the selected frequency. These maps are induded in the County Hydrology Manual (10, 50. and 100 yr maps included in the Design and Procedure Manual). (2) Adjust 6 hr precipitation (if necessary) so that it is within the range of 45% to 65% of the 24 hr precipitation (nol applicaple to Desert), (3) Plot 6 hr precipitation on the right side of the chart. (4) Draw a line through the point parallel to the plotted lines. (5) This line Is the lntenslty-duratlon curve for the location being analyzed. Application Form: (a) Selected frequency J£:L.... year (b) Pe = ..L..fL In .• P24 = 5....L. ;:4 = '58 %(21 (C) Adjusted P6(2) = -h&..in . (d) tx = _ min. (e) I = __ in.lhr. Note: This chart replaces the Intensity-Duration-Frequency curves used since 1965. Ptl .. ,. ··f.5[""2·:·.:·2;t: 3 :.3.,.~.; .. ~ ....... 4~.~.: .. 5 :.~~~.: ·.if Duration 11;1 I I I·' 11:1,1 ........... '$ 2.63 3.9515,27·6,59·7.90' 9.22:10.,54 1l.86 13.17114.49.15,81 ............ :7 ':2: 1,2:: ~:f~f~:~~.; ?:~(6::in.4( 8.48 : 9.54 : 10.60[11.66; 12:7i 10 . ~:~ .• g:~~~§:~?l1:?L~!~~ :.5:~.1. ~,?~."..?:§~ ..... M2 .. ~.Jl:n •. 19., '1. ... 1~ .1·~Q.)'.~i!.?:~2.i.;Hl:t.~·~.9.:.~,§4;.5,19 .. ~·~.1.; E?:19 ;.r..tL'?:J~. 20 1,08.1.62. 2.,1!).: l?:.~~. ~:~~ .?:?J ... 1.&1... .. _1:~.~.: . .§!~~ ~.?.~~.; 9,16 . ~~ "O.:!:l.3. : 1.40~ 1.~?~,~,~~, 2.8.0.3,27[3.73, 4.20 , 4.67 : 5.13 i 5.6,0. :,0 0.83; 1.24( t.!l?12,!,7 )l.49. 2,~of 3:3~ .. ; .~.7!3.: 4 . .1?14 .. ~ : ,!,98 ........ ~ .0..69 \1.0.31 1.3,8; 1.72.2.07,2.41: 2.76,3.10, 3.45~ 3.79; 4.13 50 M010,901.1.J.!t 1.49 .. 1 .• ?9 )?:Q.9L?·3~ .. ~§~ .. ?:~.~ ~:g~i.~,.9ll. ........ ~ 0:?3 ;0.80[1.06: 1,33.1,59.1.86: 2,12.2.39.2,65 i 2.92! 3,18 90 0.41 :O.Gli 0.82'1.02 1.23' 1.43l1.63; 1:94 2,04; 2.25; 2,45 -.. '''1~f:O:34 :0.511 iis£ii o:ssi ':6(·i:j9~"i'.36; ·1.5~ ; '(70 i 1'.87 i 2:04' .... J~ .9"~_.0.44L~:5~L<?:.?~..;.~,8.U,.q~; 1 .. 1.~: 1.3~ , 1.4?: 1:?2..L E§ . ...... J~ .. '!'?l? ,9.~91.11:5~;~.!;?5 •. n!l.~~,~.'.: .1.0~ : ... l·J.t) .. ; .. t·,~!.~ .1.4~': 1.~? '" .... ~~ . .9:~.r~1.~3,.9..~.:.I1.~.:<?:~5.;~:7(U1·87 i 0.98 . 1:<>S,,:. 1 ... ~9.U:;lQ .. ~ JJ: ~9 . 0.28~ Q,!3!l.J.O,~? . O:~; Q.~, .9.7.~ .l .. Q.,!,5.:. q,~ ... q~~.l.1 ,.1.3. 360 0.17 ·0.2510.33' 0.42· 0.SO.0.58 0.67; 0.75; 0.84 0.92; 1.00 FIGURE @] - ------------------- San Diego County Hydrology Manual Date: June 2003 Table 3-1 Section: Page: RUNOFF COEFFICIENTS FOR URBAN AREAS Land Use Runoff Coefficient "C" Soil TyEe NRCS Elements Conn Elements %IMPER, A B Undisturbed Natural Terrain (Natural) Permanent Open Space 0* 0.20 0.25 Low Density Residential (LDR) Residential, 1.0 DU/A orless 10 0.27 0.32 Low Density Residential (LDR) Residential, 2.0 DU/A or less. 20 0.34 0.38 Low Density Residential (LDR) Residential, 2.9 DU/A or less 25 0.38 0.41 Medium Density Residential (MDR) Residential, 4.3 DU/A or less 30 0.41 0.45 Medium Density Residential (MDR) Residential, 7.3 DU/A or less 40 0.48 0.51 Medium Density Residential (MDR) Residential, 10.9 DU/A or less 45 0,52 0,54 Medium Density Residential (MDR) Residential, 14.5 DU/A or less 50 0.55 0.58 High Density Residential (HDR) Residential, 24.0 DU/A or less 65 0.66 0.67 High Density Residential (HDR) Residential, 43.0 DU/A orless 80 0.76 0.77 CommerciallIndustrial (N. Com) Neighborhood Commercial " 80 0,76 0.77 ConunerciallIndustrial (G, Com) General Commercial 85 0.80 0.80 Commercia1JIndustrial (O.P. Com) Office Professional/Commercial 90 0.83 0.84 CommerciallIndustrial (Limited I,) Limited Industrial 90 0.83 0.84 CommerciallIndustrial~nera1 1.) General Industrial 95 0.87 0.87 C 0.30 0.36 0.42 0.45 0.48 0.54 0.57 0.60 0.69 0.78 0.78 0.81 0,84 0.84 0.87 3 6 of 26 D 0.35 0.41 0.46 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, forthe 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). DUI A ::; dwelling units per acre NRCS = National Resources Consexvation Service 3-6 I I I I I I I I I I I I I I I I II I I San Diego County Hydrology Manual Date: June 2003 Section: Page: 3 12 of 26 Note that the Initial Time of Concentration should be reflective of the generalland·use at the upstream end of a drainage basin. A single lot with an area of two or less acres does not have a significant effect where the drainage basin area is 20 to 600 acres. Table 3-2 provides limits of the length (Maximum Length (LM» of sheet flow to be used in hydrology studies. Initial Ti values based on average C values for the Land Use Element are also included. These values can be used in planning and design applications as described below. Exceptions may be approved by the "Regulating Agency" when submitted with a detailed study. . Table 3-2 MAXIMUM OVERLAND FLOW LENGTH (LM) & INITIAL TIME OF CONCENTRATION (Ti) Element* DU/ .5% 1% 2% 3% 5% 10% Acre LM Ti LM Ti LM Ti LM Ti LM Ti LM Ti Natural 50 13.2 70 12.5 85 10.9 100 10.3 100 8.7 100 6.9 LDR 1 50 12.2 70 11.5 85 10.0 100 9.5 100 8.0 100 6.4 LDR 2 50 11.3 70 10.5 85 9.2 100 8.8 100 7.4 100 5.8 LDR 2.9 50 10.7 70 :10.0 85 8.8 95 8:'1 100 7.0 100 5.6 MDR 4.3 50 10.2 70 9.6 80 8.1 95 7.8 100 6.7 100 5.3 MDR 7.3 50 9.2 65 8.4 80 7.4 95 7.0 100 6.0 100 4.8 MDR 10.9 50 8.7 65 7.9 80 6.9 90 6.4 100 5.7 100 4.5 MDR 14.5 50 8.2 65 7.4 80 6.5 90 6.0 100 5.4 100 4.3 HDR 24 50 6.7 65 6.1 75 5.1 90 4.9 95 4.3 100 3.5 HDR 43 50 5.3 65 4.7 75 4.0 85 3.8 95 3.4 100 2;~7 N.Com 50 5.3 60 4.5 75 4.0 85 3.8 95 3.4 100 2 . .7 G.Com 50 4.7 60 4.1 75 3.6 85 3.4 90 2.9 100 2.4 O.P.lCom 50 4.2 60 3.7 70 3.1 80 2.9 90 2.6 100 2.2 Limited 1. 50 4.2 60 3.7 70 3.1 80 2.9 90 2.6 100 2.2 General 1 50 3.7 60 3.2 70 2.7 80 2.6 90 2.3 100 1.9 *See Table 3-1 for more detailed description 3·12 I I I I I I I I I I I I I I I I I I I bE Feet 5000 4000 Tc Tc L ~E EQUAnON = C~~3)O.385 ;: = = Time of concentration (hours) Watercourse Distance (miles) Change in elevation along effe<:tive stope line (See Figure 3-5)(feet) 3000 2000 "-00 000-, 500' " 400 ',~ ,% 300 ,~ , 200 100 5 bE , , '\. " L ''\. Miles Feet '\. '1 " ~ 3000 0.5 , L SOURCE: California Division of Highways (1941) and Kirpich (1940) , Nomograph for Determination of " , Tc Hours Minutes , , , Tc 30 20 5 nme of COncentration (Te) or Travel nme (Tt) for Natural Ykrtersheds 1 FIGURE ~ I I I I I I I I I I I I I I 1-+--1.5'---+-1 1~=·01s.-..~ __ 2% _ _0=.0175 --------~------~ 2% Concrete _j-"':+::rn-:.==t:===-eP;;;iiVed~-~~-=R=ES=IDE=N1l=AL~STREET Gutter ONE SIDE ONLY 2 3 4 5 6 7 8 9 10 20 30 40 50 Discharge (C.F.S.) EXAMPLE: Given: Q :: 10 S = 2.5"10 Chart gives: Depth = O.A., Velocity = 4,. f.p.s. SOURCE: San Diego County Department of Special District Services Design Manual FIGURE Gutter and Roadway Discharge -Velocity Chart ~ ----~ ~ \ '" ),}!_\ f:) _.. \ I 01 \ \ I I I I ! / I I \ I " 16+00 =3.'3 CFS QIOO= 5. 2 CFS ---- o r -r- I ------- , 15+00 + L =-625~ - J.58 ACRES :/0% + SOIL GROUP B + ---------- 4:1i SLOPE 8 CE~6ij) SfHT DISTANCE CORR/,DOIi', PER FINAL I1AP O. iT At ------"--- 0% IMP r I I I I ,,/ ------ I ( PRIVATE SHARED A(.(.c;"'i't--J.l1 '-'r-l~<, /l UTILITY CA:;tf1t::I'.!. 61.21' 14+00 13+00 RECONST. DR/VEWA Y TO -PROPOSED STREET II1PROVEI1ENTS S5 8 DWG 422-r) 70 00 \J r.) -/~~ 0 ~ ~\I-)J ~ J '-/ + I ____ 0_ • - -, .l--, \ --- Q- '. T HYDROLOGY POST-DEVELOPMEN . 0 0 -a <> P 0 00 H YDROLOGY . PRE-DEVELOPMENT --------- "'o~ I \ \ 0 --~f \ " " 1---,.,'71 Tr 4 A C \ 50%/111'1':-\ \: :.:--.'-':! ~~771>~\ \ ------+ I "- ~\ ) \ 1 J J • (1)r,;,r;P \ I \ I I I I I I I I I I '\,; \. \ " "\ fo()' "'-"'. 0 JIIJB • I I 0 && I I I t I I I I I I I I I I I I I I I I I I \ • \ SCALE 1'=40' \....,-,_.- --------- + + SCALE 1"=40' + ------ -~ -- \ ------ + CT 03-/3 . ·neering . Eng 1 dLand SUf1)~ors -I Civil Engineers an Professzona .do. CA 92029 MAP -Q2/QI0/Q/00 HYDROLOGY n. Ddvt:, Suite E. Escoruh ac:bcll.net 600 South An~60 897-2165 &-Maili MlJI,enesh@p PhOIlC760 741·3sn . .. . ,