7016 EVERGREEN WAY 2016-01-01 MF Import

� Sunrise Services•Drainage Study 5. D�T�NTION HYDRAULIC RESULTS (cont.) ( DETENTION PIPE S17_ING The enclosed apncndices contain the cumputer results, which indicuted the I'ollowing required detention sizing: n; The "Design" Detention Pipc is equivalent to 80.0 If of �l8" diameter plastic AllS � pipe. Design Volume = 977 cf b) The Oudet is a conventional 54" Manhole. Over[loa� is by 12"Riser at elevation 463.300 c) A[�vo-orifice oudet structure releases the allowed 17o�vs as indicated in the follo�ving scction. � Required Q100 Volume = 977 cf plus 42%= 1,387.34 Cr Avail�ble Volume = 113 LL' x 48" pipe - 1,417 cf = 1.45 times required detention S' of 54" Manholes @ 15.9 CP/FI' = 127.2 cf 100' of 48" ADS @ 12.6 CF/Ft = 1,260 cf � 4' of 30" ADS connector @ 4.9I CF/Ft = 19.6d c( Available Detention Total = 1,406.84 > 1387 cf t Dead Stor�ge W.Q. Volume Requireci - Cr25 CP' ([3ased upon the 6-month, 24-hour Developed storm runof� RESTRICTION DEVICE DESIGN The conventional orifice #1 contains a 0.27-incli (1/4") orifice at elevation 4579�1. The result of this orifice design was to release 0.012 cfs, which equals � 50% of die 2-year undeveloped n�noff of 0.024 cfs fulfilling the Washington DOE & I{PA requirement. The oudet stnicture Ihen matches or exceeds the larger DOE design storm perfornmnce requirements of the 10-year and 100-yenr undeveloped events. The rele.ise structure includes a 191 (1•7/S") second ariGce cut in the standpi��e at elevation 462.54. � NOTG: Per Cverett code �Ilo�ti�ance tl�e ori(ice is incrensed tu (1.5" (1/2"). In the site 100-year design stot�n, Ihe developed peak t7ow of 0.165 cfs is reduced to the undeveloped peak flow of Qa100 = 0.065 cfs, based upon the historical � condition described. The results for the design Combination Sh�ucture (Double Orifice) are given in the LEVEL POOL TABLE SUMMARY in the attachment p:�ges. This is the computer's match for the perl'ormance criteria. ! WIitiTIiltN CNGWGERti.INC. /� PROI[(.T:UL?D7a � �3