71-3z <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 />ject Name: Oaklelclih Meadows Cohousinq Date: 3/11/201 <br />3 <br />ject Address Oakleiah Lane Permit Number: <br />Eugene, OR 97402 Catchment ID: Rain Garden 4 <br />iigner: Michael A Cox <br />npany: SSW Engineeers Inc. <br />structions: <br />Complete this form for each drainage catchment in the project site that is to be sized per the Presumptive Approach, <br />Provide a distinctive Catchment ID for each facility coordinated with the site basin map to correlate the appropriate <br />calculations with the facility. <br />The maximum drainage catchment to be modeled per the Presumptive Approach is 1 acre (43.560 SF) <br />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 />I Pollution Reduction (PR) Yes <br />Flow Control (FC) Yes <br />Destination (DT) No 'An infl1ration facility must be chosen as the facility type to meet destination requirements <br />Data-Post <br />Total Square Footage Impervious Area= 1554 sqft Total Square Footage Pervious Area=~sgft <br />Impervious Area CN= 98 Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= 1654 sft Time of Concentration Post Development= min <br />. <br />Weighted Average CND 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 to/hr (see Note 4) Destination Design= in/hr <br />Design Soil Infiltration Rate= 2.5 in/hr Soil Infiltration Rate <br />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 />Data <br />Facility Type= Filtration Rain Garden <br />Facility Surface Area= 140 sgft <br />Surface Width=1 71ft <br />Facility Surface Perimeter= 54 ft <br />Surface Length=[ 201ft <br />Facility Bottom Area= 68 sgft <br />Facility Side Slopes=~to 1 <br />Max. Ponding Depth <br />i <br />Facility Bottom Perimeter= 42 ft <br />in Stormwater Facility= <br />61in <br />Basin Volume= 54.2 cf <br />Depth of Growing Medium (Soil)=1 18 in <br />Ratio of Facility Area to Impervious Area= 0.090 <br />1413 <br />3/11/2013-10:55 AM 1 <br />