1 <br />l <br />-2:7/__,r; <br />Stormwater Surface Filtration/Infiltration Facility Sizing Spreadsheet <br />24 Hour Storm, NRCS Type 1 A Rainfall Distribution <br />City of Eugene <br />Version 2.1 <br />Project Name: Oakleigh Meadows, Cohousing Date: 3/11/2013 <br />Project Address: Oakleicth Lane Permit Number: <br />Eugene, OR 97402 Catchment ID: Rain Garden 14 <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 1D 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 'M Infiltration facility must be chosen as the facility type to meet destination requirements <br />Data-Post <br />Total Square Footage Impervious Area= 2834 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= 2834 sit Time of Concentration Post Development7-1 :51 min <br />Weighted Average CN= 98 <br />Site Data-Pre Development (Data in this sect-ion is only used if Flow Control is required) <br />Pre-Development CN= 85 Time of Concentration Pre-Development= 10 min <br />Soli Data <br />Tested Soil Infiltration Rate= 2.5 in/hr (See Mote 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 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 Type= Filtration Rain Garden <br />Facility Surface Area= 240 sgft <br />Surface Width=1 101ft <br />Facility Surface Perimeter= 68 fl <br />Surface Length=1 241ft <br />Facility Bottom Area= 147 sgft <br />Facility Side Slopes= to 1 <br />Max. Ponding Depth <br />I <br />Facility Bottom Perimeter= 56 ft <br />61in <br />In Stormwater Facility= <br />Basin Volume= 99.0 cf <br />Depth of Growing Medium (Soil)=l 18 in <br />Ratio of Facility Area to Impervious Area= 0.085 <br />3/11/2013-10:57 AM 11433 <br />