l <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 Information <br />Project Name: Oakleinh Meadows Cohousing Date: 3/1112013 <br />Project Address: Oakleigh Lane Permit Number: <br />Eugene, OR 97402 Catchment ID: Rain Garden 14 <br />Designer: Michael ACox <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 />Design Requiremefits: <br />Choose "Yes" from the dropdowh 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 raclity type to meet destination requirements <br />Site Data-Post Development <br />Total Square Footage Impervious Area= 2834 sqft Total Square Footage Pervious Area= <br />sgft <br />Impervious Area CN= 98 Pervious Area CN= 85 <br />~ <br />Total Square Footage of Drainage Area= 2834 sft Time of Concentration Post Development= min <br />Weighted Average CN: 98 <br />Site Data-Pre Development " .(Data in this sectionis only used if Flow. Control. is.requ!red) . <br />Pre-Development CN= 85 Time of Concentration Pre-Development--10 min <br />Soil Data <br />Tested Soil Infiltration Rate= <br />2.5 <br />in/hr (See Note 4) Destination Design= in/hr <br />Design Soil Infiltration Rate= <br />2.5 <br />in/hr Soil Infiltration Rate <br />Design.Stotms Used For Calculations <br />Requirement <br />Rainfall 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 />Facility-D. t3 _ <br />Facility Type= <br />Filtration Rain Garden Facility Surface Area= <br />240 <br />sqft <br />Surface Width= <br />10 <br />ft Facility Surface Perimeter- <br />68 <br />ft <br />Surface Length= <br />24 <br />ft Facility Bottom Area= <br />147 <br />sqft <br />Facility Side Slopes= <br />3 <br />to 1 Facility Bottom Perimeter- <br />56 <br />ft <br />Max Ponding Depth <br />In Stormwater Facility= <br />6 <br />in Basin Volume= <br />99.0 <br />cf <br />Depth of Growing Medium (Soil)= <br />L____ 18 in Ratio of Facility Area to Impervious Area= <br />0.085 <br />r <br />I~ <br />3/1112013-10:57 AM 1 605- <br />