Il/;7~_ <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: Oakleigh Meadows Cohousing Date: 3/11/2013 <br />Project Address: Oakleiah Lane Permit Number: <br />Eugene, OR 97402 Catchment ID: Rain Garden 6 <br />Designer: Michael A Cox . <br />Company: SSW Enoineeers 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 6 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 Requirements: <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 -An infiltration facility must be chosen as the facTty type to meet destination requirements <br />lte:Data-Post Development <br />Total Square•Footage Impervious Area= <br />4151 <br />sgft Total Square Footage Pervious Area= <br />0 sqft <br />Impervious Area CN= <br />98 <br />. <br />Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= <br />4151 <br />sft Time of Concentration Post Development= min <br />Weighted Average CN= <br />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= <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 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 />Eacility-Data - - : _ _ _ . _ <br />Facility Type= <br />Filtration Rain Garden Facility Surface Area= <br />340 <br />sqft <br />Surface Width= <br />lo <br />ft Facility Surface Perimeter- <br />88 <br />ft <br />Surface Length= <br />34 <br />ft . Facility Bottom Area= <br />217 <br />sqft <br />Facility Side Slopes= <br />3 <br />to 1 Facility Bottom Perimeter= <br />76 <br />ft <br />Max. Ponding Depth <br />in Stormwater Facility= <br />6 <br />in Basin Volume= <br />141.5 <br />cf <br />4 <br />4 Depth of Growing Medium (Soil)= 18 in Ratio of Facility Area to Impervious Area= 0.082 <br />3/11/2013-10:55 AM . 1 589 <br />