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For the desien of the detentlon svstem: <br /> �/ 1) Determine one A;marv;o,� and one AP,,,,;ow for the developed site area,so tl�at <br /> A�mp. + Ap��,,= A�o� (1.49 actes) <br /> �i 2) Determine the dme of concentration for the developed site conditions. <br /> �/3) Detcrmine the 2 yeaz, 10 year, and 100 year hydrographs for the developed azea <br /> �� � --��F) Route each hydrograph through the proposed detention system. <br /> � rn� i/ �) Show that the rele;ase rates from the detention system do not exceed the following: <br /> ,��C�S - 1/2 the exi�ting 2 yeaz peak rate for the developPd 2 yeaz l;ydrograph <br /> r�,��W ��, - the 10 year exisdng rate for the 10 yeaz developed hydrugraph <br /> fl�� . - the 100 yeaz existing rate for the 100 yeaz developed hydrograph <br /> C <br /> For the desicn of the runoff t*eatment: <br /> �?F� I) I�ternune the required treatment volwne <br /> -the required treatment volnme is the 6 month, 24hour storm runoff volume from <br /> the developed site _ 32�Q�, /� <br /> -� t' <br /> -the 6 month, 24-hour storm precipitadon is 0.99 inches. <br /> � ; 2) Provide 1 f the required treatment volutne as dead storage, in accordance with City <br /> stan, u: s see section 3 of the City's Stormwater Management Manual for a complete list <br /> ofdesign criteria): <br /> a) "dead"storage is storage below the invert elevation of the outlet pipe(s) - dead <br /> storage dces not"drain out". <br /> � b) IS% of the treatment volume (minimum) must be dead storage in a�hallow (0 to <br /> 2.5 feet deep with a maximum average depth of 2 feet),vegetated surface pond <br /> � c) a minimum volume must be dead storage 3 to 6 :eet deep. Find this volume using <br /> the following equation: <br /> minimum"deep" volume= 1676.5 x Qo x H <br /> where Qo= (the 6 month, 24-hour storm volume in cubic feet)/86,400 seconds; and <br /> H= the depth of the dead storage <br /> (�(�e k�� <br /> ��� �ux+ �'aw �, -�� ��� <br /> 1e� 5 � 5 ei� r�` <br /> v�� �Z �1Jd��G ,�,"� t ��\J (,,` • <br /> (f,��2 P JL�r �r�1 � x�k �9 <br /> t � <br /> -� yJtij,,,`a����dYr �Jo��� ��4�Nf � � <br />