1 ~~z <br />Stormwater Surface Filtrationllnfiltration Facility Sizing Spreadsheet <br />24 Hour Storm, NRCS Type 1A Rainfall Distribution <br />City of Eugene <br />Project Name: <br />Project Address <br />Designer: <br />Oakleidh Meadows Cohousinoi <br />oakleigh Lane <br />Eugene, OR 97402 <br />Michael A Cox <br />SSW Enalneeers Inc. <br />Date: 311112013 . <br />Permit Number: <br />Catchment ID: Rain Garden 9 <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 topsoillgrowing medium. <br />"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 Mirdiiitrationfacility must bechosen asthefacility type tomeet destination reguirements <br />ISife Data-Post Development 1 <br />Total Square Footage Impervious Area= 1592 sqft Total Square Footage Pervious Areal sgft <br />Impervious Area CN= 98 Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= 1592 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)" <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= in/hr <br />Design Soil Infiltration Rate= 2.5 in/hr Soil Infiltration Rate <br />Design Storms Used For Calculations <br />Requirement <br />Rainfall De th <br />Design Storm <br />Pollution Reduction <br />1.41inches <br />lWaterQuality <br />Flow Control <br />3.61inches <br />Flood Control <br />Destination <br />3.61inches <br />Flood Control <br />Facility-Data..._... _ . <br />Facility Type= Filtration Rain Garden <br />FacilitySurface Area= 150 sgft <br />Surface Width=~ 6 ft <br />Facility Surface Perimeter= 62111 <br />Surface Length=[ 25 R <br />Facility Bottom Area= 66 sgft <br />Facility Side Slopes= 3 to 1 <br />Facility Bottom Perimeter=1 50 ft <br />Max. Ponding Depth <br />in Stormwater Facility= 6 in <br />Bashi Volume= 56.2 cf <br />Depth of Growing Medium (Soil)=J 18 in <br />Ratio of Facility Area to Impervious Area= 0.094 <br />3/11/2013-10:56 AM 5-95 <br />. Version 2.1 - I <br />