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 Information ' <br />ject Name: Oakleiah Meadows Cohousing Date: 3111/2013 <br />ject Address: Oakielgh Lane Permit Number: <br />Eugene, OR 87402 Catchment ID: Rain Garden 11 <br />signer: Michael A Cox <br />npany: SSW Fncrineeers Inc. <br />istructions: <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" fi•om 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 lnffll allon facility must he chosen as the facility type to meet destination requirements <br />Site Data-Post Development <br />Total Square Footage Impervious Area= 2330 sgft . Total Square Footage Pervious Area=sgft <br />Impervious Area CN= 98 Pervious Area CN= 85 <br />Total Square Footage of Drainage Area= 2330 sft Time of Concentration Post Development= min <br />Weighted Average CN= 98 <br />Site Data-Pre Development (Data in this sgcfiorVIs 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 in/hr (See mote 4) Destination Design= in/hr <br />Design Soli Infiltration Rate- 2.5 in/hr Soil-Infiltration Rate <br />1Design"Stprms 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 />[C}estination <br />3.6 <br />inches <br />Flood Control" <br />t; <br />lFacfiftData_ - <br />Facility Type= Filtration Rain Garden <br />Facility Surface Area= <br />216 <br />sqft <br />Surface Width=1 61 ft <br />Facility Surface Perimeter= <br />84 <br />ft <br />Surface Length=1 361ft <br />Facility Bottom Area= <br />99 <br />sgft <br />to 1 <br />Facility Side Slopes= <br />Facility Bottom Perimeter= <br />72 <br />ft <br />1R <br />Max. Ponding Depth <br />I <br />in Stormwater Facility= <br />611n <br />Basin Volume= <br />81.0 <br />of <br />Depth of Growing Medium (Soil)=L___ 18 in <br />I <br />Ratio of Facility Area to Impervious Area= <br />0.093 <br /> <br />3/11/2013-10:56 AM <br />'r <br />1 599 <br />