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 Information <br />Project Name: Oakleigh Meadows Cohousinn Date: 3111/2013 <br />Project Address: Oakleigh Lane Permit Number: <br />Eugene. OR 97402 Catchment ID: Rain Garden 11 <br />Designer: Michael A Cox <br />Company: SSW Engineeers]nc: <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 />"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 most be chosen as the facility type to meet deslinatlon requirements <br />Site Data-Post <br />Total Square Footage Impervious Area= 2330 sgft <br />Impervious Area CN= 98 <br />Total Square Footage Pervious Area=sgft <br />Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= 2330 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) J <br />I Pre-Development CN= 85 Time of Concentration Pre-Development= 10 min <br />Soil Data <br />Tested Soil Infiltration Rate= 2.5 In/hr(SeeNote4) Destination Design= in/hr <br />Design Soil Infiltration Rate= 2.5 in/hr Soil Infiltration Rate <br />For Calculations <br />Requirement <br />Rain <br />If Depth <br />Design Storm <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= 216 <br />sgft <br />Surface Width=l 61ft. Facility Surface Perimeter= 84~ <br />ft <br />Surface Length=1 361ft Facility Bottom Area= 99 <br />sqft <br />Facility Side Slopes=1 31to 1 Facility Bottom Perimeter= 721 <br />, <br />ft <br />Max. Ponding Depth <br />1 <br />1 <br />in Stormwater Facility= <br />6 <br />in Basin Volume= ]8 <br />cf <br />I <br />Depth of Growing Medium (Soil)=l 18 in Ratio.of Facility Area to Impervious Area= <br />3/11/2013-10:56 AM 11427 <br />