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 Cohousing Date: 3/11/2013 <br />Project Address: Oakleiah Lane Permit Number: <br />Eugene _OR 97402 Catchment ID: Rain Garden 3 <br />Designer: Michael A Cox I <br />Company: SSW En ineeers 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 />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 requiiemenls <br />k <br />Site Data-Post Development <br />Total Square Footage Impervious Area= 1854 sqft Total Square Footage Pervious Area= ~sgft. <br />Impervious Area CN= 98 Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= 1554 sft Time of Concentration Post Development= min <br />Weighted Average Cl 98 <br />[Site Dale-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 Date <br />Tested Soil Infiltration Rate= 2.5 in/hr {see Note 4) Destination Design= in/hr <br />Design Soil infiltration Rate= 2.5 Whir Soil Infiltration Rate <br />[Design Storms Used For Calculations <br />Requirement <br />Rainfall Depth <br />Design Storm <br />IPolution Reduction <br />1.4 <br />inches <br />Water Quality <br />how control <br />3.6 <br />inches <br />Flood Control <br />I <br />Destlnation <br />3.6 <br />inches <br />Flood Control <br />Data <br />\ Facility Type=1 Filtration Rain Garden <br />[ Facility Surface Area=l 1801sgft <br />Surface Width=1 61 ft <br />Facility Surface Perimeter= 72 ft <br />Surface Length=1 301ft <br />Facility Bottom Area= 81 sqft <br />Facility Side Slopes=1 3lto 1 <br />Max. Ponding Depth <br />Facility Bottom Perimeter= 60 ft <br />in Stormwater Facility=. 61in <br />Basin Volume= 67.5 cf <br />Depth of Growing Medium (Soil);18 in <br />Ratio of Facility Area to Impervious Area= 0.097 <br />1411 <br />3/1112013.10:54 AM 1 <br />