4 <br />4 <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: 3111/2013 <br />Project Address: Oakleigh'Lane Permit Number: <br />Eugene. OR 97402 Catchment ID: Rain Garden 7 <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 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 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 FaaTity type to meet destination requirements <br />Site Data-Post Development <br />Total Square Footage Impervious Area= <br />2121 <br />sgft Total Square Footage Pervious Area= sqft <br />Impervious Area CN= <br />98 <br />Pervious Area CN= 85 <br />Total Square Footage of Drainage Area- <br />2121 <br />sft Time of Concentration Post Development--C~5 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 />Facilitl(Data_ - _ - - - - - - <br />Facility Type= <br />Filtration Rain Garden <br />Facility Surface Area= <br />189 <br />sqft <br />Surface Width= <br />7 <br />ft Facility Surface Perimeter- <br />68 <br />ft <br />Surface Length= <br />27 <br />it Facility Bottom Area= <br />96 <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 />73.5 <br />cf <br />Depth of Growing Medium,(Soil)= <br />18 <br />in Ratio of Facility Area to Impervious Area= <br />0.089 <br />3111/2013-10:55 AM <br />591 <br />