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CITY OF EVERETT DRAINAGE CALCULATIONS (less than 5 acres) <br />ri=nrina Plan, LSA 2769 <br />Total area, acres = <br />Area to remain undeveloped = acres = <br />Net area for detention calculation? <br />Criteria, from Everett Basin Map <br />3.956 <br />3.956 <br />05-Jun-92 <br />03:34 PM <br />Design Storm <br />_____________ <br />yr , <br />Pre -development <br />._0 <br />1.5 <br />yr <br />Basin: OTHER <br />= <br />post -develop <br />ground peak runoff <br />area, <br />runoff: <br />total <br />Type of cover: <br />slope: rate, cfs/ac: <br />acres• <br />- ----------- <br />(existing)_ <br />----2.00% <br />3.956 <br />0.59 <br />cfs <br />__ _ <br />0.150 x <br />cfs <br />woods/forest <br />2.00% 0.310 x <br />cfs <br />lawn/landscaping <br />2.00% 0.720 x <br />cfs <br />earth/gravel <br />2.00% 1.320 x <br />------- <br />imperv. roofs,USE: <br />-------- <br />3.96 <br />0.59 <br />cfs <br />Peak rate of runoff <br />=here <br />The <br />For flows less than <br />0.130 cfs, use 0.130 <br />/ 3.956 <br />cfs. <br />acres <br />= <br />�a150ucfs/acre <br />the equivalent of <br />0,593 cfs <br />is <br />pD..N RATE OF RUNOFF <br />Ground Slope <br />5.00€ NF. <br />10.00$ <br />NA-- <br />20 --- <br />Table 2 Freq, <br />yr 2.101 NA <br />-------------------- <br />------ -- -- <br />------------------ --- <br />--------------- <br />2 0.002 NA 0.003 NA <br />0.004 <br />NA <br />NA <br />0.00 <br />0.150 <br />GOOds/i0r8St <br />5 0.070 NA 0.100 U. <br />liA 0.210 NA <br />0.125 <br />0.265 <br />NA <br />0320 <br />10 0.150 <br />_ <br />---------------------------------------NA <br />--------------------------------------_ <br />5 NA <br />2.111 <br />10.00% <br />3A <br />20.00€ <br />Table 3 <br />Freq, yr -------------------------- <br />-- - ----- <br />---------------- <br />0.1 <br />- --- - - ------------- <br />2 0.070 NF. 0.100 <br />0.120 <br />0.310 <br />0.390 <br />launs/landscape <br />5 0.210 0.250 <br />NA 0.410 NA <br />0.510- <br />fA-- <br />0.630 <br />10 0.310 <br />-- - -------------------------------------------------------------- <br />2.00€ 11A 5.00€ Nx <br />10.00€ <br />liA <br />20.00% <br />Table 4 <br />Freq, yr ------------------ <br />-------------- <br />----------------- <br />--------------- <br />" <br />2 0.3tp liA 0.480 <br />0.510 <br />NA <br />Y"r. <br />0.650 <br />0.870 <br />each/gravel <br />•A <br />5 0.560 NA O.T00 !4 <br />0.860 <br />0.800 <br />0.960 <br />NA <br />1.040 <br />A 0.720 NA <br />- <br />-- - <br />---------- <br />------- - - - -- <br />---- -- ------ ----- -'- - --- <br />&A <br />2.00% NA 5---- <br />1D.00€ <br />liA <br />20.D0$ <br />Table 5 <br />Fceq, yr ----- <br />--- - <br />--------__-.040 <br />1.010 <br />NA <br />----------------------------Z <br />0.910 NA 0.970 NA <br />NA <br />0.910 <br />1.250 <br />NA <br />0.150 <br />itpecvious <br />5 liA 1.210 <br />NA 1.400 NA <br />i, 450 <br />- <br />1, <br />1.500 <br />10 1.320 <br />