1 '~-/3z_ <br />Stormwater Surface Filtration/Infiltration Facility Sizing Spreadsheet <br />24 Hour Storm, NRCS Type 1A Rainfall Distribution <br />City of Eugene <br />Project Name: <br />Project Address: <br />Designer: <br />Company: <br />Instructions: <br />Qaklelah Meadows Cohousino <br />Oakleigh Lane <br />Eugene, OR 97402 <br />Michael A Cox <br />SSW Engineeers Inc. <br />Date: 3/11/2013 <br />Permit Number: <br />Catchment ID: Rain Garden 7 <br />1. Complete this form for each drainage catchment in the project site that is to be sized perthe Presumptive Approach. <br />2. Provide a distinctive Catchment ID for each facility coordinated with the site basin map to correlate the appropriate <br />calculations with the facility. <br />3. The maximum drainage catchment to be modeled per the Presumptive Approach is 1 acre (43,560 SF) <br />4.For infiltration facilities in Class A or 8 soils where no infiltration testing has been perfromed use an infiltration rate of 0.5 in/hr. <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 requirements <br />Dade-Post <br />Total Square Footage Impervious Area= 2121 sqft <br />Impervious Area ( 98 <br />Total Square Footage of Drainage Area= 2121 sft <br />Weighted Average ( 98 <br />Total Square Footage Pervious Area=~sgft <br />Pervious Area CN= 85 <br />Time of Concentration Post Development= min <br />(Site Data-Pre Development (Data in this section Is only used if Flow Control is required) I <br />I Pre-Development CN= 85 Time of Concentration Pre-Development= 10 min I <br />Data <br />Tested Soil Infiltration Rate= 2 5 to/hr(SeeNote 4) Destination Design= in/hr <br />Design Soil Infiltration Rate= 2.5 in/hr Soli Infiltration Rate <br />Storms Used For Calculations <br />Requirement <br />Rainfall Depth <br />Design Storm <br />Pollution Reduction <br />1.4 <br />inches <br />Water Quali <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 <br />Facility Surface Area= 189 sgft <br />Surface Width=l 71ft <br />Facility Surface Perimeter= 68 ft <br />Surface Length=1 271111 <br />Facility Bottom Area= 96 sqft <br />Facility Side Slopes =1 31to 1 <br />Facility Bottom Perimeter= 56 It <br />Max. Ponding Depth <br />in Stormwater Facility= I 61in <br />Basin Volume= 73.5 cf <br />Depth of Growing Medium (Soil)=. 18 in <br />Ratio of Facility Area to Impervious Area= 0.089 <br />Version 2.1 <br />1419 <br />3/11/2013-10:55 AM 1 <br />