Stormwater Surface Filtration/Infiltration Facility Sizing Spreadsheet <br />24 Hour Storm, NRCS Type 1A Rainfall Distribution <br />City of Eugene <br />Version 2.1 <br />Name: <br />Oaklelgh Meadows Cohousin4 <br />Address: <br />Oakleiah Lane <br />Eugene, OR 97402 <br />:r: <br />Michael A Cox <br />ny: <br />SSW Engineeers Inc. <br />Date: 3/11/2013 <br />Permit Number: <br />Catchment ID: Rain Garden 13 <br />I nstructions: <br />Complete this form for each drainage catchment in the project site that is to be sized per the Presumptive Approach. <br />Provide a distinctive Catchment ID for each facility coordinated with the site basin map to correlate the appropriate <br />calculations with the facility. <br />The maximum drainage catchment to be modeled per the Presumptive Approach is 1 acre (43,560 SF) <br />=or infiltration facilities in Class A or B soils where no infiltration testing has been perfromed use an infiltration rate of 0.5 inlhr <br />For all facilities use a maximum soil infiltration rate of 2.5 in/hr for topsoil/growing medium. <br />Choose "Yes" from the dropdown boxes below next to the design standards requirements for.this facility. <br />Pollution Reduction (PR) Yes <br />Flow Control (FC) Yes <br />Destination (DT) NO An infiltration facility must be chosen as the facility type to meet destination requlrements <br />Site Data-PostDevelopment. <br />Total Square Footage Impervious Area= 2352 sgft Total Square Footage Pervious Area=~sgft <br />Impervious Area Cl 98 Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= 2352 sft Time of Concentration Post Development= min <br />I <br />Weighted Average CN= 98 I <br />Site Data-Pre Development (Data in this section Is only used if Flow Control Is required) . <br />Pre-Development CN= 85 Time of Concentration Pre-Development= 10 min <br />Soli Data <br />Tested Soil Infiltration Rate= 2.5 in/hr (see Note 4) Destination Design= in/hr <br />Design Soil Infiltration Rate= 2.5 in/hr Sol] Infiltration Rate <br />Storms Used For Calculations <br />Requirement <br />Rainfall Depth <br />Design Ston <br />Pollution Reduction <br />1.4 <br />inches <br />Water Quality <br />Flow Control <br />3.6 <br />inches <br />Flood Control <br />Destination <br />3.6 <br />inches <br />Flood Control <br />Data <br />Facility Type= Filtration Rain Garden Facility Surface Area= 210 sgft I <br />Surface.Width=( 71 ft Facility Surface Perimeter= 74 ft <br />Surface Length=1 301ft Facility Bottom Area= 108 sgft <br />. Facility Side Slopes=] 31to 1 Facility Bottom Perimeter= 62 ft <br />Max. Ponding Depth <br />In Stormwater Facility= I 61 in Basin Volume= 81.7 cf <br />Depth of Growing Medium (Soil)=l 18 in Ratio of Facility Area to Impervious Area= 0.089 <br />1431 <br />3/11/2013-10:56 AM 1 <br />