7/3-t- <br />StormwaterSurface Filtration/Infiltration Facility Sizing Spreadsheet <br />24-Hour Storm, NRCS Type 1A Rainfall Distribution <br />City of Eugene <br />Version 2.1 <br />Project Name: OakleiAh Meadow-s-Cohousing Date:.3/11/2013 <br />Project Address: Oakieigh Lane Permit Number: <br />Eugene, OR 97402. Catchment ID: Rain Garden 4 <br />Designer: MichaelA Cox <br />Company: SSW Encilneeers Inc. <br />Instructions: <br />1. Complete this form for each drainage catchment in the project site that is to be sized per the 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 o r 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 Inlhrfor topsoillgrowing 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 lnfilirawn facility mustbe chosen as the facility type to meet deslinalion requirements <br />(Site Data-Post Development <br />Total Square Footage Impervious Area= 1554 sqft <br />Impervious Area CN= 98 <br />Total Square Footage of Drainage Area= 1554 sit. <br />Weighted Average CN= 98 . <br />Total Square Footage Pervious Area= 0 sqft <br />Pervious Area CN= 85 <br />Time of Concentration Post Development= min <br />iSite Data-Pre Development (Data in this*sectloh is only used if Flow Control is required) <br />Pre-Development CN= . 85 Time of Concentration Pre-Development= - 10 min - <br />Tested Soil Infiltration Rate= 2.5 inlhr (see Note 4) Destination Design= in/hr I <br />Design Soil Infiltration Rate= . 2.5 in/hr Soil Infiltration Rate <br />! <br />Requirement Rainfall Depth <br />Design Storm <br />Pollution Reduction I 1.41inches <br />Water Quality <br />!Flow Control I 3.61inches <br />Flood Control <br />Destination 3.6 inches <br />Flood Control <br />Facility Type= Filtration Rain Garden Facility Surface Area= 140 sgft <br />Surface Width=J 71ft Facility Surface Perimeter= 54 ft <br />Surface Length=1 201ft Facility Bottom Area= 68 sgft <br />Facility Side Slopes=1 31to 1 Facility Bottom Perimeter= 42 ft <br />Max, Ponding Depth <br />in Stormwater Facility=in Basin Volume= 54.2 1 cf <br />. Depth of Growing Medium (Soil)=L___ 18 in Ratio of Facility Area to Impervious Area= 0.090 <br />3111/2013-10:55 AM 1 585 <br />