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The convo] strucWre of the facility serves as Uoth an oudet control and an emergency spillway. <br /> Details of the control structure are shown in Exhibi[ ]3. The open top of the control structure <br /> acts as the emer�ency spilhvay. ' <br /> I <br /> The orifice sizes for the proposed infilVatiorJdetention pond were calculated to pass the <br /> prcde��eloped 2-, 10-, and 100-}'ear flo���s from the PSA sitc and detain the stonnwater runoff <br /> from the CSR site. S[ormwater from Ihe FSA site is treated and detained to Streambank L-rosion <br /> Control standards prior to entering the proposed stonm�ater sqstem. The outflow hydrographs <br /> from the FSA detention f.cilit}'were added to both'[he pre-developcd and devcloped CSR <br /> � hqdrographs to account for the flows from the FSA site and size the control sWcture's orifices. <br /> I Table 4 shows the stonmvater Ilows used in the orifice design. The surFace discharge is the <br /> controlled discharge through the orifces, u�hile the infiltration discharge is the scepa�e dischar;e <br /> tliroueh the eround. 'I'he oritice sizes arc listed belo�v: <br /> ( Orifice size for elevation 356.SS fee[=2 inches <br /> O�ifiice size for elevation 376.13 Ceet= S 1/2 inches <br /> Orifice size for elevation 37337 feet = 8 3/4 inches <br /> I <br /> Table 4 -Sform�vater flows Design Summory <br /> �(cis) <br /> Evenl In(low Dischor e <br /> Exislin Gevelo ed Surlare Inlillration Tolal <br /> SD;"c of 2-�'car 0.5G 18.50 0.56 1.64 2.20 <br /> 10-r'enr 3.08 2S.63 2.97 1.97 4.94 <br /> 100-�car 7.05 42.G2 7A5 2.32 937 <br /> � The Pond OuUct Structure, located upstream of the Pond Contro] Structure, has a 1-inch diameter <br /> � orifice and a concrete division wall. The Pond Outlet Structure is designed to "[hrolNe" the <br /> surfacc runoff Flows from 1/2 inch, 24-hour stomis to the control structure and increases the <br /> I volume of infiltration and groundwatcr recharge. The Pond Oude[Structure was not takcn into , <br /> account in the desien of the Pond Control StrucWre orifices. Details of thc Pend Oudet Stnicture '�' <br /> are sho���n in �xhibit 13. �-' <br /> IA 6-inch outfall pipe nms from SDA1fI#lc to an :uea of thc pond ���est of[hc catch basin (see <br /> L:xhibit S). This pipc scn�cs to divert stonnwatcr to a relati��cl}' fl:it arca of thc pond that is ` <br /> approximatcly 200 tect frum the pond outict. 'fhis diversion ��'ill hclp incrcasc the volume of j. <br /> infiltration and ground�aatcr recharge �vithin the Glem��ood Creck basin. The maximum Oow �,,"� <br /> through thc outfnll pipc is 296 cfs, which ���as c;ilculatcd from thc hcad on [hc pipe du�ing thc `�� <br /> 100-t'car dc;ign stonu. 'l�he fio�ti� calcul;uions :m sftown in Al�pcndia f3. �i�:' <br /> ' �_,-: <br /> � <br /> ,.r: <br /> Y� <br /> ��'Fl <br /> �' <br /> 8�: <br /> i;; <br /> (SR Aisocelyd B�evvd FeYif eJ Ame 2L�01 <br /> � S�rrtnwctaSlef'Im � -9- ' � �, �� �� - i� i . <br /> s <br />