1/~5t_ <br />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 />Project Name: Oakleigh Meadows Cohousing Date: 3M1/2013 <br />Project Address: Oakleigh Lane Permit Number: <br />Eugene, OR 97402 Catchment ID: Rain Garden 1 <br />Designer: Michael A Cox <br />Company: SSW Engineeers 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 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 />Choose "Yes" from the dropdown boxes below next to the design standards requirements for this facility. <br />I Pollution Reduction (PR) Yes <br />Flow Control (FC) Yes <br />f Destination (DT) No `M Infiltration facility must be chosen as the facility type to meet destination requirements <br />Site Data-Post Development <br />Total Square Footage Impervious Area= 1923 sgft Total Square Footage Pervious Area=sgft <br />Impervious Area CN= 98 Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= 1923 sft Time of Concentration Post Development= min <br />Weighted Average CN= 98 <br />Site Data-Pre Development (Data in this section is only used if Flow Control is required) 4 <br />Pre-Development CN= 65 Time of Concentration Pre-Development= 10 min I <br />Soil 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 Soil Infiltration Rate <br />Storms Used For Calculations <br />Requirement <br />Rainfall Depth <br />Design Storm <br />Pollution Reduction <br />1.4 <br />inches <br />WaterQualit <br />Flow Control <br />3.6 <br />inches <br />Flood Control <br />Destination <br />3.6 <br />inches <br />Flood Control <br />Facility Data <br />Facility Type= Filtration Rain Garden <br />Facility Surface Area= <br />182 <br />sgft <br />Surface Width=1 71ft <br />Facility Surface Perimeter= <br />66 <br />ft <br />Surface Length=1 261ft <br />Facility Bottom Area= <br />92 <br />sgft <br />Facility Side Slopes=1 31to 1 <br />Facility Bottom Perimeter= <br />54 <br />ft <br />Max. Ponding Depth <br />in Stormwater Facility= 6 in <br />Basin Volume= <br />70.7 <br />cf <br />Depth of Growing Medium (Soil)=l 18 in <br />Ratio of Facility Area to Impervious Area= <br />0.095 <br />3111/2013-10:54 AM 11407 <br />