StormwaterSurface Filtration/Infiltration Facility Sizing Spreadsheet <br />24 Hour Storm, NRCS Type 1A Rainfall Distribution <br />City of Eugene <br />Version 2.1 <br />Name: Oakleigh Meadows Cohousing Date: 3111/2013 <br />Address: Oakleigh Lane Permit Number: <br />Eugene. OR 97402 Catchment ID: Rain Garden 6 <br />?r: Michael A Cox <br />ny: SSW Engineeers Inc. <br />Instructions: <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 B 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 />"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 'M infillmllon facility must be chosen as the facility type to meet destination requirements <br />Total Square Footage Impervious Area= 4151 sqft <br />Impervious Area CN= 98 <br />Total Square Footage Pervious Area=~sgft <br />Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= 4151 sft <br />Weighted Average CN= 98 <br />Time of Concentration Post Development= min <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 />Soil Data <br />Tested Soil Infiltration Rate= 2 5 in/hr (see Note 4) Destination Design= lnlhr <br />Design Soil Infiltration Rate= 2.5 in/hr Soil Infiltration Rate <br />Storms Used For Calculations <br />Requirement <br />Rainfall Depth <br />Design Storm <br />Pollution Reduction <br />1.41inches <br />Water Quality <br />Flow Control <br />3.61inches <br />Flood Control <br />Destination <br />3.61 inches <br />Flood Control <br />Data <br />Facility Type= Filtration Rain Garden <br />Facility Surface Area= 340 sgft <br />Surface Width=1 <br />101ft <br />Facility Surface Perimeter= 88 ft <br />Surface Length=1 <br />341ft <br />Facility Bottom Area= 217 sgft <br />Facility Side Slopes=1 <br />31to'l <br />Facility Bottom Perimeter= 76 ft <br />Max. Ponding Depth <br />I <br />1 <br />in Stormwater Facility= <br />6 <br />in <br />Basin Volume= 141.5 cf <br />Depth of Growing Medium (Soil)=l 18 in <br />Ratio of Facility Area to Impervious Area= 0.082 <br />1417 <br />3/11/2013-10:55 AM 1 <br />