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2009-10-16_PERMIT FILE - M2009082 (13)
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2009-10-16_PERMIT FILE - M2009082 (13)
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Last modified
8/24/2016 3:56:13 PM
Creation date
10/20/2009 9:20:46 AM
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Template:
DRMS Permit Index
Permit No
M2009082
IBM Index Class Name
PERMIT FILE
Doc Date
10/16/2009
Doc Name
Attachment G-4, Preliminary Drainage Report
From
Lafarge West, Inc.
To
DRMS
Media Type
D
Archive
No
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Parsons Mine Lafarge West, Inc <br />Preliminary Drainage Report <br />Peak Runoff Calculations Using the Rational Method <br />Basin: P1-14 (H2) Condition: Developing Stom1 Retum Period: <br /> <br /> Basin Ch cteristics <br />Area, A: 159 acres Basin Imperviousness' (in percent), is 2 01/o <br />Distance of Overland Flow, L,,: 3,028 ft Hydrologic Soils Group A Percent of Basin:: 0.01y, <br />Distance of Channelized Flow, L : 3,090 ft Hydrologic Soils Group 8 Percent of Basin: 74.2°/ <br />Average Basin Slope, & 0.01174 fVft Hydrologic Soils Groups C 8 D Percent of Basin:. 25.8% <br />Slope of Channelized Flow, S.: 0.00258 ft/ft Conveyance Coeffcient2, C,,:: 15 <br /> <br /> Runoff'G efficient <br />Runoff Coefficient Eouations For 100-yr storm Return Period: K,, _ -0.25i + 6.32 <br />C,=K, + ' 2 <br />(1.31 i - 1.44i2 + 1.1351 - 0.12) for. CA z 0 else CA = 0, <br />K cD _ -0.391 + 0.46 <br />Cco°Kco +; (0.858i3 - 0.78612 + 0.7741 + 0.04) For 10-yr Storm Return Period: K <br />A °-0.14 +0.17 <br />Cu=(CA + Cc-D)/2 <br />KcD =-0.181+0.21 <br /> For 5-yr Storm Return Period: KA _ -0.081 + 0.09 <br />K _-01Q' <br />Return Period Cam,„ps,a CA Ge Cco KA KCD <br />5-Year 0.103 0.000 0.082 0.163 0.088 0:108 <br />10-Year 0.190 0.069 0.165 0.262 0.167 0.206 <br />100-Year 0.400 0.217 0.362 0.507 0.315 0.452 <br />Total time of concentration equation' <br />Lesser of': tc=1 + t, <br />or t,=L / 180 +10 (if in urban area) <br />Overland flow travel time equation: f<= 162 <br />4=(0.395' (1.1 - CS) ` sgrt(L,)) / SO.33 ti= 94 <br />Channelized flow travel time equation: ti= 68 <br />4=Lc (V' 60) where V= (C„ ` Sw05) V= 0.762 <br />Rational Method Equation: <br />Q ° Cconipos 1. ' I ' A <br />Return <br />Period CC-„V„ <br />i <br />..55--Year 0.103 0.74 <br />E 0.190 0.88 159 26.5 <br /> 0.400 1.39 159 87.9 <br />Notes: <br />1: Basin imperviousness determined from guidelines in LIFCD Drainage Criteria Manual Table RO-3 <br />2: Conveyance coefficient determined from guidelines in DFCD Drainage Criteria'Manual Table RO-2 <br />3: Minimum t, is 10 min. for non-urban areas and 5 min. f r urban areas <br />CD U.11 <br />Rainfall Intensity <br />Rainfall intensity Equation: <br />1=(28.5 - P, (10 + Tc)o.re6 where P,,,, is the 1 hr point rainfall depth <br />min <br />min <br />min <br />fits <br /> Pit, I <br />Retum Period in in / hr <br />5-Year 1.49 0.74 <br />10-Year 1.76 0.88 <br />100-Year 2.78 1.39 <br />n / hr acres Cf5 <br /> <br />Flow Rate <br /> <br /> <br />I A Q <br /> <br />Dater 9/1712009
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